WO2010060038A1

WO2010060038A1 - Polycarbonates as adhesives in electronics manufacturing

Info

Publication number: WO2010060038A1
Application number: PCT/US2009/065528
Authority: WO
Inventors: Scott D. Allen
Original assignee: Novomer Inc
Current assignee: Novomer Inc
Priority date: 2008-11-23
Filing date: 2009-11-23
Publication date: 2010-05-27
Anticipated expiration: 2011-05-23
Also published as: TW201026805A

Abstract

The present invention provides adhesive compositions and methods of using the same (e.g., wafer or flexible substrate processing methods). The adhesives of the present invention incorporate aliphatic polycarbonates with improved characteristics relative to prior art polycarbonates.

Description

POLYCARBONATES AS ADHESIVES IN ELECTRONICS MANUFACTURING

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U. S. C. § 119(e) to U.S. provisional application serial number 61/117,229, filed November 23, 2008, and U.S. provisional application serial number 61/121,422, filed December 10, 2008, the entire contents of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The invention pertains to the fields of semiconductor and micro fabrication processing technology. More particularly, the invention pertains to thermally decomposable adhesives comprising poly(alkylene carbonate) polymers and methods of using such adhesives for temporary bonding of substrates (e.g., semiconductor materials and other components) during microfabrication processes.

BACKGROUND

In the field of semiconductor technology, myriad structures for stacking chips, power devices, smart cards, and thin substrates for processors have one thing in common: semiconductor material such as silicon. Wafer thinning will soon be an essential process step for most of the devices fabricated and packaged henceforth. The key driving forces for thinned wafers are improved heat dissipation, three-dimensional stacking, reduced electrical resistance, and substrate flexibility. Handling of thin and ultrathin substrates however is non- trivial because of their fragility and tendency to warp and fold. The substrates must be supported during the backside grinding process and the thinned substrates need continued support through subsequent processes such as lithography, deposition, etc.

Geometrical limitations are an additional incentive for substrate thinning. Via holes are etched on the backside of a substrate to facilitate frontside contacts. In order to construct a via using common dry-etch techniques, geometric restrictions apply. For substrate thicknesses of less than 100 μm, a via having a diameter of 30-70 μm is constructed using dry-etch methods that produce minimal post-etch residue within an acceptable time. For thick substrates, vias with larger diameters are needed. This requires longer dry-etch times and produces larger quantities of residue, thus significantly reducing throughput. Larger vias also require larger quantities of metallization which is more costly. Therefore, for backside processing, thin substrates can be processed more quickly and at lower cost.

Thin substrates are also more easily cut and scribed into ICs. Thinner substrates have a smaller amount of material to penetrate and cut and therefore require less effort. No matter what method is used (sawing, scribe and break, or laser ablation), ICs are easier to cut from thinner substrates. Most semiconductor wafers are thinned after frontside operations. For ease of handling, wafers are processed (i.e., frontside devices) at their normal full-size thicknesses, e.g., 600-700 μm. Once completed, they are thinned to thicknesses of 100-150 μm. In some cases (e.g., when hybrid substrates such as gallium arsenide (GaAs) are used for high-power devices) thicknesses may be taken down to 25 μm.

Mechanical substrate thinning can be performed by bringing the wafer surface into contact with a hard and flat rotating horizontal platter that contains a slurry. The slurry may contain abrasive media along with chemical etchants such as ammonia, fluoride, or combinations thereof. The abrasive provides "gross" substrate removal, i.e., thinning, while the etchant chemistry facilitates "polishing" at the submicron level. The wafer is maintained in contact with the media until an amount of substrate has been removed to achieve a targeted thickness.

For a wafer thickness of 300 μm or greater, the wafer can be held in place with tooling that utilizes a vacuum chuck or some means of mechanical attachment. When wafer thickness is reduced to about 300 μm or less, it becomes difficult or impossible to maintain control with regard to attachment and handling of the wafer during further thinning and processing. In some cases, mechanical devices may be made to attach and hold onto thinned wafers, however, they are subject to many problems, especially when processes may vary. For this reason, the wafers are mounted onto a separate rigid (carrier or handling) substrate. This substrate becomes the holding platform for further thinning and post-thinning processing. Carrier substrates can be composed of materials such as sapphire, quartz, certain glasses, and silicon, and usually exhibit a thickness of at least about 1000 μm. Substrate choice will depend on how closely matched the coefficient of thermal expansion (CTE) is between each material.

In a related technology, thinner and/or more flexible substrates are quickly becoming popular as a base for electronic circuits. Flexible substrates can include a wide variety of materials including very thin layers of metal, such as stainless steel, any of a myriad of plastics, etc. Once a desired electronic component, circuit, or circuits are formed on a surface of the flexible substrate, the circuit can be attached to a final product or incorporated into a further structure. Typical examples of such products or structures are active matrices on flat panel displays, RFID tags on various commercial products in retail stores, a variety of sensors, etc. The handling of these thin flexible substrates presents many of the same challenges described above with respect to the handling of thin silicon wafers. Therefore, it is desirable to mount flexible substrates to a rigid carrier for ease of handling and processing.

Several methods have been described for mounting thin silicon wafers or flexible substrates to rigid carriers. One method that has been used to mount an active wafer or flexible substrate to a carrier substrate comprises the use of a cured bonding composition. The major drawback with this approach is that the bonding composition must be chemically removed, typically by dissolving in a solvent. This is very time-consuming and reduces throughput rates. Furthermore, the use of the solvent adds to the cost and complexity of the process, and it can be hazardous, depending upon the solvent required to dissolve the bonding composition.

Another method for mounting an active wafer or flexible substrate to a carrier substrate is via a thermal release adhesive tape. This process has two major shortcomings.

First, the tapes have limited thickness uniformity across the active wafer/carrier substrate interface, and this limited uniformity is often inadequate for ultra-thin wafer handling. Second, the thermal release adhesive softens at such low temperatures that the bonded wafer/carrier substrate stack cannot withstand many typical wafer processing steps that are carried out at higher temperatures.

Using temporary adhesives to attach the wafer or flexible substrate to a rigid carrier substrate offers an efficient solution. The requirements for such adhesive materials include ease of application, coating uniformity with minimal thickness variation across the wafer, good adhesion to a wide variety of surfaces, thermal stability in processes such as dielectric deposition and metallization, and ease of removal to allow high throughput. An additional requirement for these materials is stability in harsh chemical environments posed by processes such as etching, electroplating, and resist removal.

Aliphatic polycarbonates (APCs) meet many of these requirements and their use for these applications has been described. In particular, poly (propylene carbonate) (PPC) has been explored as a temporary adhesive in wafer processing methods. These methods are described, for example, in US Patent Application Serial No. 11/171,956 and International Patent Application Publication No. WO 2008/005979.

In these previously disclosed methods, the PPC used has been synthesized using catalysts exemplified by Inoue et al. (see, for example US Patent Nos. 3900424, and 3953383), or has been of a commercially available grade such as QPAC-40™ (available from Empower Materials Inc.) or Unity 2203 (available from Promerus Inc.). These compositions consist of PPC having significant quantities of ether linkages (>5%), low head-to-tail ratios (for example <70% head-to-tail orientation of repeating units) high polydispersity (for example PDI >1.5) and a relatively broad decomposition temperature Td range (for example, a >30 ⁰C difference between 5% mass loss and 95% mass loss according to thermo gravimetric analysis (TGA)). Hereinafter, these materials are referred to collectively as "prior art PPC".

PPC is desirable for use as an adhesive in these methods since it shows complete burnout at a relatively low temperature and the products of decomposition are able to diffuse and escape through solid substrates. However, it has been found that the prior art PPC has shortcomings in certain applications due to its lack of stability at temperatures well below Td(onset). This limits the processes in which the adhesives can be used since any processing steps involving elevated temperatures may result in premature debonding.

SUMMARY OF THE INVENTION

The present invention encompasses the recognition that polycarbonate compositions having improved thermal stability are useful as adhesives in a number of applications. In certain embodiments, the present invention provides aliphatic polycarbonate compositions and methods of using those compositions to form thermally decomposable bonding compositions. In some embodiments, provided compositions support substrates on a carrier during processing steps such as wafer thinning, vapor deposition, metallization and other related steps. In some embodiments, the present invention provides compositions and methods for bonding components to wafers (e.g., integrated optical devices and multi-level chips). In some embodiments, the present invention provides compositions and methods for use in microfluidics and precision optics.

DEFINITIONS

Definitions of specific functional groups and chemical terms are described in more detail below. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75^th Ed., inside cover, and specific functional groups are generally defined as described therein. Additionally, general principles of organic chemistry, as well as specific functional moieties and reactivity, are described in Organic Chemistry, Thomas Sorrell, University Science Books, Sausalito, 1999; Smith and March March 's Advanced Organic Chemistry, 5^th Edition, John Wiley & Sons, Inc., New York, 2001; Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., New York, 1989; Carruthers, Some Modern Methods of Organic Synthesis, 3^r Edition, Cambridge University Press, Cambridge, 1987; the entire contents of each of which are incorporated herein by reference.

Certain compounds of the present invention can comprise one or more asymmetric centers, and thus can exist in various stereoisomeric forms, e.g., enantiomers and/or diastereomers. Thus, inventive compounds and compositions thereof may be in the form of an individual enantiomer, diastereomer or geometric isomer, or may be in the form of a mixture of stereoisomers. In certain embodiments, the compounds of the invention are enantiopure compounds. In certain embodiments, mixtures of enantiomers or diastereomers are provided.

Furthermore, certain compounds, as described herein may have one or more double bonds that can exist as either the Z or E isomer, unless otherwise indicated. The invention additionally encompasses the compounds as individual isomers substantially free of other isomers and alternatively, as mixtures of various isomers, e.g., racemic mixtures of enantiomers. In addition to the above-mentioned compounds per se, this invention also encompasses derivatives of these compounds and compositions comprising one or more compounds.

As used herein, the term "isomers" includes any and all geometric isomers and stereoisomers. For example, "isomers" include cis- and ^rαra-isomers, E- and Z- isomers, R- and S-enantiomers, diastereomers, (ϋ)-isomers, (L)-isomers, racemic mixtures thereof, and other mixtures thereof, as falling within the scope of the invention. For instance, an stereoisomer may, in some embodiments, be provided substantially free of one or more corresponding stereoisomers, and may also be referred to as "stereochemically enriched."

Where a particular enantiomer is preferred, it may, in some embodiments be provided substantially free of the opposite enantiomer, and may also be referred to as "optically enriched." "Optically enriched," as used herein, means that the compound is made up of a significantly greater proportion of one enantiomer. In certain embodiments the compound is made up of at least about 90% by weight of a preferred enantiomer. In other embodiments the compound is made up of at least about 95%, 98%, or 99% by weight of a preferred enantiomer. Preferred enantiomers may be isolated from racemic mixtures by any method known to those skilled in the art, including chiral high pressure liquid chromatography (HPLC) and the formation and crystallization of chiral salts or prepared by asymmetric syntheses. See, for example, Jacques, et al., Enantiomers, Racemates and Resolutions (Wiley

Interscience, New York, 1981); Wilen, S.H., et al., Tetrahedron 33:2725 (1977); Eliel, E.L. Stereochemistry of Carbon Compounds (McGraw-Hill, NY, 1962); Wilen, S.H. Tables of Resolving Agents and Optical Resolutions p. 268 (E.L. Eliel, Ed., Univ. of Notre Dame Press, Notre Dame, IN 1972).

The terms "halo" and "halogen" as used herein refer to an atom selected from fluorine

(fluoro, -F), chlorine (chloro, -Cl), bromine (bromo, -Br), and iodine (iodo, -I).

The term "aliphatic" or "aliphatic group", as used herein, denotes a hydrocarbon moiety that may be straight-chain (i.e., unbranched), branched, or cyclic (including fused, bridging, and spiro-fused polycyclic) and may be completely saturated or may contain one or more units of unsaturation, but which is not aromatic. Unless otherwise specified, aliphatic groups contain 1-30 carbon atoms. In certain embodiments, aliphatic groups contain 1-12 carbon atoms. In certain embodiments, aliphatic groups contain 1-8 carbon atoms. In certain embodiments, aliphatic groups contain 1-6 carbon atoms. In some embodiments, aliphatic groups contain 1-5 carbon atoms. In some embodiments, aliphatic groups contain 1—4 carbon atoms. In some embodiments, aliphatic groups contain 1-3 carbon atoms. In some embodiments, aliphatic groups contain 1-2 carbon atoms. Suitable aliphatic groups include, but are not limited to, linear or branched, alkyl, alkenyl, and alkynyl groups, and hybrids thereof such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

The term "unsaturated", as used herein, means that a moiety has one or more double or triple bonds.

The terms "cycloaliphatic", "carbocycle", or "carbocyclic", used alone or as part of a larger moiety, refer to a saturated or partially unsaturated cyclic aliphatic monocyclic or bicyclic ring systems, as described herein, having from 3 to 12 members, wherein the aliphatic ring system is optionally substituted as defined above and described herein. Cycloaliphatic groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, cycloheptenyl, cyclooctyl, cyclooctenyl, and cyclooctadienyl. In some embodiments, the cycloalkyl has 3-6 carbons.

The terms "cycloaliphatic", "carbocycle" or "carbocyclic" also include aliphatic rings that are fused to one or more aromatic or nonaromatic rings, such as decahydronaphthyl or tetrahydronaphthyl, where the radical or point of attachment is on the aliphatic ring. In certain embodiments, the term "3- to 8-membered carbocycle" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring. In certain embodiments, the terms "3- to 14-membered carbocycle" and "C₃-M carbocycle" refer to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring, or a 7- to 14-membered saturated or partially unsaturated polycyclic carbocyclic ring. In certain embodiments, the term "C3_2o carbocycle" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring, or a 7- to 20-membered saturated or partially unsaturated polycyclic carbocyclic ring.

The term "alkyl," as used herein, refers to saturated, straight- or branched-chain hydrocarbon radicals derived from an aliphatic moiety containing between one and six carbon atoms by removal of a single hydrogen atom. Unless otherwise specified, alkyl groups contain 1-12 carbon atoms. In certain embodiments, alkyl groups contain 1-8 carbon atoms.

In certain embodiments, alkyl groups contain 1-6 carbon atoms. In some embodiments, alkyl groups contain 1-5 carbon atoms. In some embodiments, alkyl groups contain 1-4 carbon atoms. In certain embodiments, alkyl groups contain 1-3 carbon atoms. In some embodiments, alkyl groups contain 1-2 carbon atoms. Examples of alkyl radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, sec-butyl, sec- pentyl, iso-pentyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n- decyl, n-undecyl, dodecyl, and the like.

The term "alkenyl," as used herein, denotes a monovalent group derived from a straight- or branched-chain aliphatic moiety having at least one carbon-carbon double bond by the removal of a single hydrogen atom. Unless otherwise specified, alkenyl groups contain 2-12 carbon atoms. In certain embodiments, alkenyl groups contain 2-8 carbon atoms. In certain embodiments, alkenyl groups contain 2-6 carbon atoms. In some embodiments, alkenyl groups contain 2-5 carbon atoms. In some embodiments, alkenyl groups contain 2-4 carbon atoms. In some embodiments, alkenyl groups contain 2-3 carbon atoms. In some embodiments, alkenyl groups contain 2 carbon atoms. Alkenyl groups include, for example, ethenyl, propenyl, butenyl, l-methyl-2-buten-l-yl, and the like.

The term "alkynyl," as used herein, refers to a monovalent group derived from a straight- or branched-chain aliphatic moiety having at least one carbon-carbon triple bond by the removal of a single hydrogen atom. Unless otherwise specified, alkynyl groups contain 2-12 carbon atoms. In certain embodiments, alkynyl groups contain 2-8 carbon atoms. In certain embodiments, alkynyl groups contain 2-6 carbon atoms. In some embodiments, alkynyl groups contain 2-5 carbon atoms, in some embodiments, alkynyl groups contain 2-4 carbon atoms, in yet other embodiments alkynyl groups contain 2-3 carbon atoms, and in yet other embodiments alkynyl groups contain 2 carbon atoms. Representative alkynyl groups include, but are not limited to, ethynyl, 2-propynyl (propargyl), 1-propynyl, and the like.

The term "aryl" used alone or as part of a larger moiety as in "aralkyl", "aralkoxy", or "aryloxyalkyl", refers to monocyclic and polycyclic ring systems having a total of five to 20 ring members, wherein at least one ring in the system is aromatic and wherein each ring in the system contains three to twelve ring members. The term "aryl" may be used interchangeably with the term "aryl ring". In certain embodiments of the present invention, "aryl" refers to an aromatic ring system which includes, but is not limited to, phenyl, biphenyl, naphthyl, anthracyl and the like, which may bear one or more substituents. Also included within the scope of the term aryl", as it is used herein, is a group in which an aromatic ring is fused to one or more additional rings, such as benzofuranyl, indanyl, phthalimidyl, naphthimidyl, phenantriidinyl, or tetrahydronaphthyl, and the like. In certain embodiments, the terms "6- to 10-membered aryl" and "C_6-10 aryl" refer to a phenyl or an 8- to 10-membered polycyclic aryl ring. In certain embodiments, the term "6- to 14-membered aryl" refers to a phenyl or an 8- to 14-membered polycyclic aryl ring. The terms "heteroaryl" and "heteroar-", used alone or as part of a larger moiety, e.g., "heteroaralkyl", or "heteroaralkoxy", refer to groups having 5 to 14 ring atoms, preferably 5, 6, or 9 ring atoms; having 6, 10, or 14 π electrons shared in a cyclic array; and having, in addition to carbon atoms, from one to five heteroatoms. The term "heteroatom" refers to nitrogen, oxygen, or sulfur, and includes any oxidized form of nitrogen or sulfur, and any quaternized form of a basic nitrogen atom. Heteroaryl groups include, without limitation, thienyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl, purinyl, naphthyridinyl, benzofuranyl and pteridinyl. The terms "heteroaryl" and "heteroar-", as used herein, also include groups in which a heteroaromatic ring is fused to one or more aryl, cyclo aliphatic, or heterocyclyl rings, where the radical or point of attachment is on the heteroaromatic ring. Nonlimiting examples include indolyl, isoindolyl, benzothienyl, benzofuranyl, dibenzo furanyl, indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H-quinolizinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, and pyrido[2,3-b]-l ,4-oxazin-3(4Η)-one. A heteroaryl group may be mono- or bicyclic. The term "heteroaryl" may be used interchangeably with the terms "heteroaryl ring", "heteroaryl group", or "heteroaromatic", any of which terms include rings that are optionally substituted. The term "heteroaralkyl" refers to an alkyl group substituted by a heteroaryl, wherein the alkyl and heteroaryl portions independently are optionally substituted. The term

"heteroaralkyl" refers to an alkyl group substituted by a heteroaryl, wherein the alkyl and heteroaryl portions independently are optionally substituted. In certain embodiments, the term "5- to 10-membered heteroaryl" refers to a 5- to 6-membered heteroaryl ring having 1 to 3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8- to 10- membered bicyclic heteroaryl ring having 1 to 4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In certain embodiments, the term "5- to 14-membered heteroaryl" refers to a 5- to 6-membered heteroaryl ring having 1 to 3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8- to 14-membered poly cyclic heteroaryl ring having 1 to 4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. As used herein, the terms "heterocycle", "heterocyclyl", "heterocyclic radical", and "heterocyclic ring" are used interchangeably and refer to a stable 3- to 7-membered monocyclic or 7-14-membered bicyclic heterocyclic moiety that is either saturated or partially unsaturated, and having, in addition to carbon atoms, one or more, preferably one to four, heteroatoms, as defined above. When used in reference to a ring atom of a heterocycle, the term "nitrogen" includes a substituted nitrogen. As an example, in a saturated or partially unsaturated ring having 0-3 heteroatoms selected from oxygen, sulfur or nitrogen, the nitrogen may be N (as in 3,4-dihydro-2H-pyrrolyl), NH (as in pyrrolidinyl), or ⁺NR (as in TV- substituted pyrrolidinyl). In some embodiments, the term "3- to 7-membered heterocyclic" refers to a 3- to 7-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In some embodiments, the term "3- to 8-membered heterocycle" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In some embodiments, the term "3- to 12-membered heterocyclic" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a 7- to 12-membered saturated or partially unsaturated poly cyclic heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In some embodiments, the term "3- to 14-membered heterocycle" refers to a 3- to 8- membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a 7- to 14-membered saturated or partially unsaturated polycyclic heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

A heterocyclic ring can be attached to its pendant group at any heteroatom or carbon atom that results in a stable structure and any of the ring atoms can be optionally substituted.

Examples of such saturated or partially unsaturated heterocyclic radicals include, without limitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl, pyrrolidonyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl, dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl, and quinuclidinyl. The terms "heterocycle", "heterocyclyl", "heterocyclyl ring", "heterocyclic group", "heterocyclic moiety", and "heterocyclic radical", are used interchangeably herein, and also include groups in which a heterocyclyl ring is fused to one or more aryl, heteroaryl, or cycloaliphatic rings, such as indolinyl, 3H-indolyl, chromanyl, phenanthridinyl, or tetrahydroquinolinyl, where the radical or point of attachment is on the heterocyclyl ring. A heterocyclyl group may be mono- or bicyclic. The term "heterocyclylalkyl" refers to an alkyl group substituted by a heterocyclyl, wherein the alkyl and heterocyclyl portions independently are optionally substituted.

As used herein, the term "partially unsaturated" refers to a ring moiety that includes at least one double or triple bond. The term "partially unsaturated" is intended to encompass rings having multiple sites of unsaturation, but is not intended to include aryl or heteroaryl moieties, as herein defined.

One of ordinary skill in the art will appreciate that the synthetic methods, as described herein, may utilize a variety of protecting groups. By the term "protecting group," as used herein, it is meant that a particular functional moiety, e.g., O, S, or N, is masked or blocked, permitting, if desired, a reaction to be carried out selectively at another reactive site in a multifunctional compound. Such protecting groups are well known in the art and include those described in detail in Protecting Groups in Organic Synthesis, T. W. Greene and P. G. M. Wuts, 3^r edition, John Wiley & Sons, 1999, the entirety of which is incorporated herein by reference. In some embodiments, a protecting group reacts selectively in good yield to give a protected substrate that is stable to the projected reactions; the protecting group is preferably selectively removable by readily available, preferably non-toxic reagents that do not attack the other functional groups; the protecting group forms a separable derivative (more preferably without the generation of new stereogenic centers); and the protecting group will preferably have a minimum of additional functionality to avoid further sites of reaction. By way of non-limiting example, hydroxyl protecting groups include methyl, methoxylmethyl (MOM), methylthiomethyl (MTM), ϊ-butylthiomethyl, (phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM), p-methoxybenzyloxymethyl (PMBM), (4- methoxyphenoxy)methyl (p-AOM), guaiacolmethyl (GUM), ϊ-butoxymethyl, 4- pentenyloxymethyl (POM), siloxymethyl, 2-methoxyethoxymethyl (MEM), 2,2,2- trichloroethoxymethyl, bis(2-chloroethoxy)methyl, 2-(trimethylsilyl)ethoxymethyl (SEMOR), tetrahydropyranyl (THP), 3-bromotetrahydropyranyl, tetrahydrothiopyranyl, 1- methoxycyclohexyl, 4-methoxytetrahydropyranyl (MTHP), 4-methoxytetrahydrothiopyranyl, 4-methoxytetrahydrothiopyranyl S,S-dioxide, l-[(2-chloro-4-methyl)phenyl]-4- methoxypiperidin-4-yl (CTMP), l,4-dioxan-2-yl, tetrahydrofuranyl, tetrahydrothiofuranyl, 2,3,3a,4,5,6,7,7a-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl, 1 -ethoxy ethyl, l-(2- chloroethoxy)ethyl, 1 -methyl- 1-methoxy ethyl, 1 -methyl- 1 -benzyloxyethyl, 1 -methyl- 1- benzyloxy-2-fluoroethyl, 2,2,2-trichloroethyl, 2-trimethylsilylethyl, 2-(phenylselenyl)ethyl, t- butyl, allyl, p-chlorophenyl, p-methoxyphenyl, 2,4-dinitrophenyl, benzyl, p-methoxybenzyl, 3,4-dimethoxybenzyl, o-nitrobenzyl, /»-nitrobenzyl, /»-halobenzyl, 2,6-dichlorobenzyl,/>- cyanobenzyl, p-phenylbenzyl, 2-picolyl, 4-picolyl, 3-methyl-2-picolyl N-oxido, diphenylmethyl, p,p '-dinitrobenzhydryl, 5-dibenzosuberyl, triphenylmethyl, α- naphthyldiphenylmethyl, /j-methoxyphenyldiphenylmethyl, άi(p- methoxyphenyl)phenylmethyl, tri(p-methoxyphenyl)methyl, 4-(4'- bromophenacyloxyphenyl)diphenylmethyl, 4,4',4"-tris(4,5- dichlorophthalimidophenyl)methyl, 4,4',4"-tris(levulinoyloxyphenyl)methyl, 4,4 ',4' '- tris(benzoyloxyphenyl)methyl, 3-(imidazol- 1 -yl)bis(4',4"-dimethoxyphenyl)methyl, 1,1- bis(4-methoxyphenyl)-l '-pyrenylmethyl, 9-anthryl, 9-(9-phenyl)xanthenyl, 9-(9-phenyl-10- oxo)anthryl, 1 ,3-benzodithiolan-2-yl, benzisothiazolyl S,S-dioxido, trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), dimethylisopropylsilyl (IPDMS), diethylisopropylsilyl (DEIPS), dimethylthexylsilyl, ϊ-butyldimethylsilyl (TBDMS), t- butyldiphenylsilyl (TBDPS), tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl, diphenylmethylsilyl (DPMS), ϊ-butylmethoxyphenylsilyl (TBMPS), formate, benzoylformate, acetate, chloroacetate, dichloroacetate, trichloroacetate, trifluoroacetate, methoxyacetate, triphenylmethoxy acetate, phenoxyacetate,/?-chlorophenoxyacetate, 3-phenylpropionate, 4- oxopentanoate (levulinate), 4,4-(ethylenedithio)pentanoate (levulinoyldithioacetal), pivaloate, adamantoate, crotonate, 4-methoxycrotonate, benzoate,/>-phenylbenzoate, 2,4,6- trimethylbenzoate (mesitoate), alkyl methyl carbonate, 9-fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate, alkyl 2,2,2-trichloroethyl carbonate (Troc), 2-(trimethylsilyl)ethyl carbonate (TMSEC), 2-(phenylsulfonyl) ethyl carbonate (Psec), 2-(triphenylphosphonio) ethyl carbonate (Peoc), alkyl isobutyl carbonate, alkyl vinyl carbonate alkyl allyl carbonate, alkyl />- nitrophenyl carbonate, alkyl benzyl carbonate, alkyl p-methoxybenzyl carbonate, alkyl 3,4- dimethoxybenzyl carbonate, alkyl o-nitrobenzyl carbonate, alkyl p-nitrobenzyl carbonate, alkyl S-benzyl thiocarbonate, 4-ethoxy- 1 -napththyl carbonate, methyl dithiocarbonate, 2- iodobenzoate, 4-azidobutyrate, 4-nitro-4-methylpentanoate, o-(dibromomethyl)benzoate, 2- formylbenzenesulfonate, 2-(methylthiomethoxy)ethyl, 4-(methylthiomethoxy)butyrate, 2- (methylthiomethoxymethyl)benzoate, 2,6-dichloro-4-methylphenoxyacetate, 2,6-dichloro-4- ( 1 , 1 ,3 ,3-tetramethylbutyl)phenoxyacetate, 2,4-bis( 1 , 1 -dimethylpropyl)phenoxyacetate, chlorodiphenylacetate, isobutyrate, monosuccinoate, (£)-2-methyl-2-butenoate, o-

(methoxycarbonyl)benzoate, α-naphthoate, nitrate, alkyl N,N,N',N '- tetramethylphosphorodiamidate, alkyl 7V-phenylcarbamate, borate, dimethylphosphinothioyl, alkyl 2,4-dinitrophenylsulfenate, sulfate, methanesulfonate (mesylate), benzylsulfonate, and tosylate (Ts). Exemplary protecting groups are detailed herein, however, it will be appreciated that the present disclosure is not intended to be limited to these protecting groups; rather, a variety of additional equivalent protecting groups can be readily identified using the above criteria and utilized in the method of the present disclosure. Additionally, a variety of protecting groups are described by Greene and Wuts {supra).

As described herein, compounds of the invention may contain "optionally substituted" moieties. In general, the term "substituted", whether preceded by the term "optionally" or not, means that one or more hydrogens of the designated moiety are replaced with a suitable substituent. Unless otherwise indicated, an "optionally substituted" group may have a suitable substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position.

Combinations of substituents envisioned by this invention are preferably those that result in the formation of stable or chemically feasible compounds. The term "stable", as used herein, refers to compounds that are not substantially altered when subjected to conditions to allow for their production, detection, and, in certain embodiments, their recovery, purification, and use for one or more of the purposes disclosed herein. Suitable monovalent substituents on a substitutable carbon atom of an "optionally substituted" group are independently halogen; -(CH₂)o-4R°; -(CH₂)o-4θR°; -0-(CH₂)o ₄C(O)OR°; -(CH₂)_{0 4}CH(OR°)₂; -(CH₂)_{0 4}SR°; -(CH₂)_{0 4}Ph, which may be substituted with R°; -(CH₂)o-₄θ(CH₂)₀-iPh which may be substituted with R°; -CH=CHPh, which may be substituted with R°; -NO₂; -CN; -N₃; -(CH₂)o-₄N(R⁰)₂; -(CH₂y₄N(R°)C(O)R°; -

N(R°)C(S)R°; -(CH₂)O ₄N(R°)C(O)NR°₂; -N(R°)C(S)NR°₂; -(CH₂)_{0 4}N(R°)C(O)OR°; - N(R°)N(R°)C(O)R°; -N(R°)N(R°)C(O)NR°₂; -N(R°)N(R°)C(O)OR°; -(CH₂)O ₄C(O)R⁰; - C(S)R⁰; -(CH₂)O ₄C(O)OR°; -(CH₂)_{0 4}C(O)N(R°)₂; -(CH₂)_{0 4}C(O)SR°; -(CH₂)₀ 4C(O)OSiR°₃; -(CH₂)O ₄OC(O)R°; -OC(O)(CH₂)_{0 4}SR-, SC(S)SR⁰; -(CH₂)_{0 4}SC(O)R°; - (CH₂)o ₄C(O)NR°₂; -C(S)NR°₂; -C(S)SR⁰; -SC(S)SR⁰, -(CH₂)_{0 4}OC(O)NR°₂; -

C(O)N(OR°)R°; -C(O)C(O)R⁰; -C(O)CH₂C(O)R⁰; -C(NOR°)R°; -(CH₂)_{0 4}SSR°; -(CH₂)₀ ₄S(O)₂R°; -(CH₂)O ₄S(O)₂OR°; -(CH₂)_{0 4}OS(O)₂R°; -S(O)₂NR°₂; -(CH₂)_{0 4}S(O)R°; - N(R^O)S(O)₂NR^O ₂; -N(R°)S(O)₂R°; -N(OR°)R°; -C(NH)NR°₂; -P(O)₂R⁰; -P(O)R°₂; - OP(O)R°₂; -OP(O)(OR°)₂; SiR°₃; -(Ci_-4 straight or branched alkylene)O-N(R°)₂; or -(Ci_-4 straight or branched alkylene)C(O)O-N(R°)₂, wherein each R° may be substituted as defined below and is independently hydrogen, Ci_8 aliphatic, -CH₂Ph, -0(CH₂)o iPh, or a 5-6- membered saturated, partially unsaturated, or aryl ring having 0^1 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or, notwithstanding the definition above, two independent occurrences of R°, taken together with their intervening atom(s), form a 3—12— membered saturated, partially unsaturated, or aryl mono- or polycyclic ring having 0^1 heteroatoms independently selected from nitrogen, oxygen, or sulfur, which may be substituted as defined below.

Suitable monovalent substituents on R° (or the ring formed by taking two independent occurrences of R° together with their intervening atoms), are independently halogen, -(CH₂)o ₂R^β, -(haloR*), -(CH₂)_{0 2}OH, -(CH₂)_{0 2}OR^β, -(CH₂)_{0 2}CH(OR*)₂; -O(haloR'), -CN, -N₃, - (CH₂)o ₂C(O)R^β, -(CH₂)_{O 2}C(O)OH, -(CH₂)_{0 2}C(O)OR^β, -(CH₂)_{0 4}C(O)N(R°)₂; -(CH₂)₀ ₂SR^β, -(CH₂)_{O 2}SH, -(CH₂)o ₂NH₂, -(CH₂)_{0 2}NHR^β, -(CH₂)_{0 2}NR'₂, -NO₂, -SiR*₃, -OSiR*₃, -C(O)SR*, -(d_₄ straight or branched alkylene)C(O)OR^β, or -SSR* wherein each R* is unsubstituted or where preceded by "halo" is substituted only with one or more halogens, and is independently selected from Ci_₄ aliphatic, -CH₂Ph, -0(CH₂)o-iPh, or a 5-6-membered saturated, partially unsaturated, or aryl ring having 0^1 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Suitable divalent substituents on a saturated carbon atom of R° include =0 and =S.

Suitable divalent substituents on a saturated carbon atom of an "optionally substituted" group include the following: =0, =S, =NNR^* ₂, =NNHC(O)R^*, =NNHC(O)OR^*, =NNHS(O)₂R^*, =NR^*, =NOR^*, -O(C(R^* ₂))_{2 3}O- or -S(C(R^* ₂))₂_₃S-, wherein each independent occurrence of R is selected from hydrogen, Ci_6 aliphatic which may be substituted as defined below, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0^- heteroatoms independently selected from nitrogen, oxygen, or sulfur. Suitable divalent substituents that are bound to vicinal substitutable carbons of an "optionally substituted" group include: -O(CR ₂)₂-₃O-, wherein each independent occurrence of R is selected from hydrogen, Ci_6 aliphatic which may be substituted as defined below, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0^- heteroatoms independently selected from nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R include halogen, -R", -(haloR"), - OH, -OR*, -O(haloR'), -CN, -C(O)OH, -C(O)OR*, -NH₂, -NHR*, -NR*₂, or -NO₂, wherein each R* is unsubstituted or where preceded by "halo" is substituted only with one or more halogens, and is independently Ci_4 aliphatic, -CH₂Ph, -0(CH₂)o-iPh, or a 5-6- membered saturated, partially unsaturated, or aryl ring having 0^- heteroatoms independently selected from nitrogen, oxygen, or sulfur.

Suitable substituents on a substitutable nitrogen of an "optionally substituted" group include

-C(O)R¹, -C(O)OR¹, -C(O)C(O)R¹, -C(O)CH₂C(O)R¹, -S(O)₂R¹, - S(O)₂NR^, -C(S)NR^, -C(NH)NR^, or -N(R^S(O)₂R¹; wherein each R^r is independently hydrogen, Ci_6 aliphatic which may be substituted as defined below, unsubstituted -OPh, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or, notwithstanding the definition above, two independent

taken together with their intervening atom(s) form an unsubstituted 3-12-membered saturated, partially unsaturated, or aryl mono- or bicyclic ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R are independently halogen, -R*, - (haloR*), -OH, -OR*, -O(haloR'), -CN, -C(O)OH, -C(O)OR*, -NH₂, -NHR*, -NR*₂, or - NO₂, wherein each R* is unsubstituted or where preceded by "halo" is substituted only with one or more halogens, and is independently Ci_4 aliphatic, -CH₂Ph, -0(CH₂)o iPh, or a 5-6- membered saturated, partially unsaturated, or aryl ring having 0^1 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

As used herein, the "term head-to-tail" or "HT", refers to the regiochemistry of adjacent repeating units in a polymer chain. For example, in the context of poly(propylene carbonate) (PPC), the term head-to-tail based on the three regiochemical possibilities depicted below:

The term head-to-tail ratio (H:T) refers to the proportion of head-to-tail linkages to the sum of all other regiochemical possibilities.

As used herein, the term "substrate" is broadly used to refer to a thin slab of material. The thickness of the slab is much less than a transverse dimension of the slab. Examples of substrates include, without being limited to, a wafer (e.g., semiconductor, quartz, fused silica, or silicon-on-insulator) a thin slab of plastic, a thin slab of metal, a thin slab of ceramic material, a slab of optical material, e.g. , a disk of optical material used to fabricate a precision optical component. Micro- or nano-devices including electronic components and circuits can be fabricated in and/or on, or bonded to, certain substrates identified above. In certain embodiments, a substrate is a flexible substrate. In some embodiments, a substrate is a wafer. In certain embodiments, a substrate is a semiconductor wafer.

As used herein, the term "semiconductor wafer" means a thin slab of semiconductor material, such as a silicon, used in the fabrication of integrated circuit and other micro- or nano-devices. The term semiconductor wafer as used herein includes wafers comprising,

SiGe, Ge, SiGeSn, GeSn, GaAs, InP, and the like. The semiconductor material can be present in crystalline form and/or amorphous form. In certain embodiments, a semiconductor wafer has a thickness between about 100 μm to about 1 mm and a diameter between about 50 mm to about 500 mm. A semiconductor wafer can serve as a substrate for microelectronic devices fabricated in and/or upon the wafer. A semiconductor wafer can undergo many micro fabrication processing steps such as doping, ion implantation, reactive ion etching, chemical etching, deposition of various materials, oxide growth, and photolithographic patterning.

The term "flexible substrate" means a non-rigid substrate which can be readily deformed under low loads, e.g., undergo out-of-plane deformations under its own weight when supported on a non-flat surface or supported at an edge. In certain embodiments, the deformations can be one-tenth the thickness of the flexible substrate or more. Micro- or nano- devices including electronic components and circuits can be fabricated in and/or on, or bonded to, flexible substrates. Examples of flexible substrates include, without being limited to, flexible plastic substrates, flexible metal substrates, and thinned substrates. In some embodiments, a flexible substrate comprises thin silicon. In some embodiments, a flexible substrate is a semiconductor wafer. In some embodiments, a flexible substrate comprises thin quartz. Flexible metal substrates include FeNi alloys (e.g., INVARTM, FeNi, or FeNi36; INVARTM is an alloy of iron (64%) and nickel (36%) (by weight) with some carbon and chromium), FeNiCo alloys (e.g., KOVAR™, KOVAR™ is typically composed of 29% nickel, 17% cobalt, 0.2% silicon, 0.3% manganese, and 53.5% iron (by weight)), titanium, tantalum, molybdenum, aluchrome, aluminum, and stainless steel. Flexible plastic substrates include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethersulfone (PES), polyimide, polycarbonate, and cyclic olefin copolymer.

The term "essentially free" as used in reference to a repeating unit or linkage of a provided polymer means that the repeating unit or linkage is not detectable by standard polymer characterization techniques. Such techniques include ¹H or ¹³C NMR.

As used herein, the term "Td₍o_nset₎" means the minimum temperature at which rapid decomposition of a polymer material occurs. This may be determined using TGA by standard methods known in the art.

As used herein, the terms "Td(5%)" and "Td(95%)" refer to the temperature at which 5% and 95% respectively of the mass of a polymer sample is lost during TGA.

As used herein, the term "T_d range" refers to the difference between T_d(95%) and T_d(5o_/0) (i.e., Td(95%) - Td(5%)).

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the carbonyl region of the C NMR spectrum of a prior art PPC polymer having a low head-to-tail ratio made with zinc carboxylate catalyst and a table showing the deconvolution of the resonances in that NMR spectrum.

Figure 2 shows the carbonyl region of the C NMR spectrum of a PPC polymer having a high head-to-tail ratio suitable for adhesives of the present invention.

Figure 3 shows a plot of the thermal stability of prior art PPC and PPC of the present invention at 200 ⁰C over 2 hours. Figure 4 shows a plot of the thermal stability of prior art PPC and PPC of the present invention at 180 ⁰C over 8 hours.

Figure 5 shows a TGA plot of prior art PPC.

Figure 6 shows a TGA plot of PPC of the present invention.

Figure 7 shows a GPC plot demonstrating the molecular weight distribution of prior art PPC.

Figure 8 shows a GPC plot demonstrating the molecular weight distribution of PPC of the present invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

1. General description of adhesive compositions

The present invention encompasses adhesive compositions for the handling of substrates. In some embodiments, a substrate is a semiconductor wafer. In some embodiments, a substrate is a flexible substrate. In certain embodiments, the invention includes adhesive compositions comprising aliphatic polycarbonate polymers having high head-to-tail ratios. In certain embodiments, the invention includes adhesive compositions comprising aliphatic polycarbonate polymers having narrow polydispersity.

Without wishing to be bound by any theory or thereby limit the scope of the claimed invention, it is believed that provided adhesive compositions comprising aliphatic polycarbonates having high head-to-tail ratios result in improved processing characteristics compared with similar adhesive compositions utilizing prior art polycarbonates having lower head-to-tail ratios; alternatively and/or additionally, it is believed that provided adhesive compositions comprising aliphatic polycarbonates having narrow polydisperisity indices may result in improved processing characteristics compared with similar adhesive compositions utilizing prior art polycarbonates having higher polydispersity; alternatively and/or additionally, it is believed that provided adhesive compositions comprising aliphatic polycarbonates having a high percentage of carbonate linkages may result in improved processing characteristics compared with similar adhesive compositions utilizing prior art polycarbonates having lower percentages of carbonate linkages.

Provided adhesive compositions show improvements including, but not limited to, one or more of: improved homogeneity of a composition when applied to a semiconductor wafer or flexible substrate, improved stability when a composition is heated to a temperature below Td(onset), reduced vapor pressure, rapid mass loss when a composition is heated to Td(onset), higher crystallinity, and more predictable burnoff characteristics.

1.1 Aliphatic polycarbonates present in adhesives

In certain embodiments, adhesive compositions of the present invention comprise poly(alkylene carbonate) with a head to tail ratio (H:T) greater than about 4:1. In certain embodiments, adhesive compositions of the present invention comprise poly(alkylene carbonate) with a head to tail ratio (H:T) greater than about 5:1. In certain embodiments, adhesive compositions of the present invention comprise poly(alkylene carbonate) with a head to tail ratio (H:T) greater than about 10: 1. In certain embodiments, adhesive compositions of the present invention comprise poly(alkylene carbonate) with a head to tail ratio (H:T) greater than about 20: 1. In certain embodiments, adhesive compositions of the present invention comprise poly(alkylene carbonate) with a head to tail ratio (H:T) greater than about 50: 1. In certain embodiments, adhesive compositions of the present invention comprise poly(alkylene carbonate) with a head to tail ratio (H:T) greater than about 100: 1.

In certain embodiments, adhesive compositions of the present invention comprise one or more aliphatic polycarbonates with a polydispersity index from about 1.0 to about 1.7. In certain embodiments, the polydispersity index of an aliphatic polycarbonate (APC) is less than 1.4. In certain embodiments, polydispersity index of an APC is less than 1.3. In certain embodiments, the polydispersity index of an APC is less than 1.2. In certain embodiments, polydispersity index of an APC is between about 1.05 and about 1.3. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 85% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 90% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 91% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 92% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 93% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 94% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 95% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 96% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 97% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 98% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 99% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that, on average in the composition, the percentage of carbonate linkages is 99.5% or greater. In certain embodiments, provided adhesive compositions comprising aliphatic polycarbonates are characterized in that ether linkages are not detectable by ¹H or ¹³C NMR. Such polycarbonates may be referred to as highly alternating, perfectly alternating, or essentially free of ether linkages.

With respect to provided polycarbonates, the present disclosure may refer to percentages of carbonate or ether linkages as complementary characteristics. Thus, the characteristic of having 90% or greater carbonate linkages will be understood as equivalent to 10% or less ether linkages (or ether content).

Aliphatic polycarbonates suitable for embodiments of the present invention can be obtained by copolymerization of epoxides and carbon dioxide in the presence of transition metal catalysts. Suitable methods are disclosed in US Patent Nos. 6,860,004, and 7,304,172, in Patent Application Serial Nos. US 11/812,102 and PCT/KR2008/002453, and in Angewandte. Chemie. International Edition in English. 2004, 3574 -3577; Journal of the American Chemical Society, 2005, 727, 10869-10878; Journal of Polymer Science-Part A: Polymer Chemistry, 2006, 44, 5182-5191; Dalton Trans. , 2006, 237-249, Journal of Polymer Science-Part A: Polymer Chemistry, 2008, 6102-6113; and Journal of the American Chemical Society, 2009, 131, 11509-11518; the entirety of each of which is incorporated herein by reference.

In certain embodiments, aliphatic polycarbonates not suitable for the present invention include those disclosed in or made using methods described in US Patent Nos. 3,900,424, and 3,953,383, more generally, polycarbonates produced by copolymerization of carbon dioxide and epoxides in the presence of heterogenous catalysts containing Group II or Group III metal salts or alkoxides may not be suitable for the present invention since these materials are characterized by relatively low head to tail ratios (H:T), relatively high PDI values, and relatively low percentages of carbonate linkages (for example, they have head to tail ratio

(H:T) lower than about 4: 1 , PDIs greater than about 1.8, or less than 90% carbonate linkages). Additionally, aliphatic polycarbonates produced by step polymerization {e.g. by reaction of phosgene with diols) may not be suitable for certain embodiments of the present invention since they typically have head to tail ratio (H:T) lower than about 4: 1 , PDIs greater than about 1.8, and less than 90% carbonate linkages.

Without being bound by any theory or thereby limiting the scope of the claimed invention, it is believed that a higher head-to-tail ratio in PPC (and similar monosubstituted aliphatic polycarbonates) enhances the thermal stability of polymers at temperatures below the thermal decomposition onset temperature. Adhesives comprising polycarbonates having higher regioregularity lose mass at a much slower rate when aged at elevated temperatures that are below a temperature at which rapid thermal decomposition commences (e.g. 10 to 50 ⁰C below the onset temperature). Alternatively and/or additionally, it is believed that adhesive compositions comprising polycarbonates with high regioregularity have sharper thermal decomposition profiles (e.g. the difference between Tds% and Td95% are less than about 20 ⁰C). Both of these features are desirable in temporary adhesives for applications described herein.

Figure 1 shows a ¹³C NMR data table of PPC typical of the commercially-available material made with zinc carboxylate catalysts. This material is typical of PPC used in all prior art adhesive compositions (e.g. QPAC-40™). As can be seen, the prior art sample has a moderate head to tail ratio with only 63% of the triads showing HT linkages. Figure 2 shows the carbonate portion of the ¹³C NMR spectrum of PPC suitable for adhesive compositions of the present invention. The sample in Figure 2 was manufactured according to methods disclosed in US 7,304,172 and has a head-to-tail ratio of greater than 90% as evidenced by the essential absence of peaks between 153.5 to 153.9 (indicative of head-to-head junctions) or above 154.4 ppm (indicative of tail-to-tail junctions). The (R,R)-(Salen- I)CoOBzFs catalyst referred to in Figure 2 has the structure:

Adhesives of the present invention incorporate aliphatic polycarbonates with improved characteristics relative to prior art polycarbonates. In certain embodiments, the present disclosure provides adhesive compositions for wafer or flexible substrate processing methods. As shown in Figs. 3 and 4, aliphatic polycarbonates used in adhesive compositions of the present invention have improved thermal stability at elevated temperatures. Compositions containing such polycarbonates are particularly useful for bonding semiconductor wafers or flexible substrates to rigid carriers since they are able to withstand higher processing temperatures without significant degradation.

As shown in Figures 3 and 4, aliphatic polycarbonates (in this case PPC) used in adhesive compositions of the present invention possess improved thermal stability at temperatures below Td(onset). The sample in Figure 4 was manufactured according to methods disclosed in US 7,304,172 and has a PDI of less than 1.2. Figure 4 shows the mass vs. time profiles for PPC sample held at a constant temperature of 180 ⁰C. The solid line shows the mass of PPC of the instant invention, while the dashed line shows the mass of QPAC-40™, typical of the material used in related prior art adhesive compositions. At 180 ⁰C, PPC of the present invention lost 10% of its mass after about 175 minutes elapsed while QPAC-40™ lost 10% of its mass within about 50 minutes. Similarly, Figure 3 shows the mass vs. time plot of samples of the same polymers when aged at 200 ⁰C. In this case 10% mass loss occurs by about 35 minutes for PPC of the present invention vs. about 15 minutes for QPAC-40™.

Furthermore, as shown in Figs. 5 and 6, the decomposition of polycarbonates incorporated into adhesives of the present invention is complete and occurs over a narrower temperature range than polycarbonates used in prior art adhesives. Figure 5 shows the TGA of PPC used in prior art adhesive methods. It is notable that there is a difference of more than 80 ⁰C between the temperature at which 5% mass is lost (207 ⁰C) and the temperature at which 95% of the mass is lost (301 ⁰C). Figure 6 shows data for PPC used in adhesive compositions of the present invention. In this case, the difference between 5% mass loss (221 ⁰C) and 95% loss (232 ⁰C) (i.e., Td range) is only 11 Celsius degrees. This sharp, clean decomposition provides adhesives with improved characteristics since debonding of a flexible substrate or semiconductor wafer from a rigid carrier can be affected more predictably and more quickly by heating an assembly for a short time at a temperature above a polycarbonate's T_d(onset).

Figure 7 shows a GPC chromatogram of a commercially-available PPC composition (QPAC-40™) made with such catalysts. This material is typical of PPC used in all prior art adhesive compositions. As can be seen, the QPAC-40™ sample is polydisperse with a PDI of about 2.2. Figure 8 shows the GPC chromatogram of PPC suitable for adhesive compositions of the present invention.

Loss of sample mass is indicative of premature decomposition of polymers and can be associated with loss of adhesive strength in adhesive compositions incorporating such polymers. Adhesives of the present invention are significantly more stable during processing steps where elevated temperatures are present than those incorporating prior art PPC compositions.

In certain embodiments, provided adhesive compositions are advantageous over known adhesive compositions in having a well defined decomposition profile (e.g., when heated to Td(onset), mass loss is rapid and complete). Without wishing to be bound by any particular theory, it is believed that a high percentage of carbonate linkages and corresponding lack of ether linkages is a contributing factor to the decomposition profile of provided compositions. For example, poly(propylene carbonate) may decompose by an intramolecular transesterification mechanism wherein a terminal hydroxyl group attacks the nearest carbonate linkage to form a 5-membered ring that releases from the polymer chain as propylene carbonate. This mechanism can effect rapid depolymerization in a perfectly alternating polycarbonate. However, if an ether linkage is encountered during depolymerization, an intramolecular transesterification mechanism must proceed via an 8- membered ring transition state. Such a transition state is much less favorable than a 5- membered transition state and would slow depolymerization accordingly. The difference may be seen in TGA scans, wherein provided compositions give a stair-step response (see Figure 6) while prior are compositions show a broader curve (see Figure 5). Alternatively and/or additionally, characteristics of provided compositions such as low PDI and/or high head-to- tail ratios may contribute to an observed decomposition profile.

In certain embodiments, adhesive compositions of the present invention comprise one or more aliphatic polycarbonates with a polydispersity index from about 1.0 to about 1.7. In certain embodiments, the polydispersity index of an APC is less than 1.4. In certain embodiments, polydispersity index of an APC is less than 1.3. In certain embodiments, the polydispersity index of an APC is less than 1.2. In certain embodiments, the polydispersity index of an APC is between about 1.05 and about 1.3.

In certain embodiments, adhesive compositions of the present invention comprise one or more aliphatic polycarbonates of formula 1.

wherein,

R^a is hydrogen, halogen, -L-OR^Z, or an optionally substituted moiety selected from the group consisting Of C_1-30 aliphatic; 3- to 14-membered carbocycle; 6- to 14- membered aryl; 5- to 14-membered heteroaryl having 1 -4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; or R^a is an optionally substituted C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain, wherein one or more methylene units are optionally and independently replaced by -NR-, -

N(R)C(O)-, -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -0-, -C(O)-, -OC(O)-, -OC(O)O- , -C(O)O-, -OC(O)N(R)-, -S-, -SO-, -SO₂-, -C(=S)-, or -C(=NR)-, and where one or more hydrogen atoms is optionally replaced with -OR^Z;

L is a C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain;

each R is independently hydrogen, optionally substituted C_1-6 aliphatic, or:

two R on the same nitrogen atom are taken together with the nitrogen atom to form a 4- to 7-membered heterocyclic ring having 0-2 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur;

each R^z is independently selected from the group consisting of hydrogen, a silyl group, a hydroxyl protecting group, or an optionally substituted group selected from the group consisting of C_1-20 acyl; C_1-20 aliphatic; 3- to 14-membered carbocycle; 6- to 14-membered aryl; 5- to 14-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

each of R , R^c, and R is independently hydrogen, halogen, or an optionally substituted group selected from the group consisting of C_1-12 aliphatic; C_1-12 heteroaliphatic having 1 -4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 3- to 14-membered carbocycle; 6- to 14-membered aryl; 5- to 14-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

wherein any of (R^a and R°), (R⁰ and R^d), and (R^a and R^b) can be taken together with their intervening atoms to form one or more optionally substituted rings selected from the group consisting of: 3- to 14-membered carbocycle; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

E is any group that can ring-open an epoxide;

G is selected from the group consisting of hydrogen, a C_1-20 acyl group, a silyl group, an optionally substituted Ci_₂o aliphatic group, an optionally substituted 6- to 14- membered aryl group, a carbamoyl group, and a hydroxyl protecting group; j is an integer from about 90 to about 15,000; k is an integer from about 0 to about 2,500; and m is the sum of j and k, wherein m is an integer from about 100 to about 17,500.

In certain embodiments, adhesive compositions of the present invention comprise one or more polymers of formula Ia:

where E, G, R^a, R^b, R^c, and R^d are as defined above, and m is an integer between about 100 and about 17,500.

In certain embodiments, adhesive compositions of the present invention comprise one or more polymers of formula 2:

where E, G, R^a,y, k, and m are as defined above.

In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 2 wherein R^a is selected from the group consisting of -H, methyl, ethyl, propyl, butyl, higher saturated aliphatic, chloromethyl, trifluoromethyl, pentafluoroethyl, higher fluoroalkyl, vinyl, allyl, phenyl, benzyl, higher unsaturated aliphatic, and CH₂OR², where R^z is as defined above. In certain embodiments, adhesive compositions comprise random-, tapered-, or block-copolymers comprising monomer units incorporating any two or more of these R^a groups.

In certain embodiments, adhesive compositions comprise polymers of formula 2 wherein R^a is selected from the group consisting of -H, methyl, ethyl, propyl, butyl, C5-30 alkyl, chloromethyl, trifluoromethyl, pentafluoroethyl, vinyl, allyl, phenyl, benzyl, CH₂OAc, CH₂OC(O)CF₃, CH₂OC(O)Et, CH₂OBz, CH₂OMe, CH₂OEt, CH₂OPr, CH₂OBu, CH₂OPh, CH₂OBn, CH₂OAlIyI, and CH₂OCF₃. In certain embodiments, adhesive compositions comprise random-, tapered-, or block-copolymers comprising monomer units incorporating any two or more of these R^a groups.

In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 3:

where E, GJ, k, and m are as defined above.

In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 3a:

where E and G are as defined above and m is an integer between about 100 and about 17,500.

In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 4:

E

where E, GJ, k, and m are as defined above. In certain embodiments, adhesive compositions of the present invention comprise one or more polymers of formula 5:

where E, G, R^a, j, k, and m are as defined above, each R^f is independently an optionally substituted C_1-10 aliphatic group, and* is an integer between 0 and 5 inclusive.

In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 6:

where E, GJ, k, and m are as defined above. In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 7:

where E, GJ, k, and m are as defined above.

In some embodiments, R^a is -L-OR^Z. In some embodiments, L is a bivalent Ci_s saturated or unsaturated, straight or branched, hydrocarbon chain. In some embodiments, one or more methylene units of L are optionally and independently replaced by -NR-, -N(R)C(O)- , -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -0-, -C(O)-, -OC(O)-, -C(O)O-, -S-, -SO-, -SO₂-, - C(=S)-, or -C(=NR)-. In some embodiments, L is a bivalent Ci_8 saturated hydrocarbon chain, wherein one or two methylene units of L are optionally and independently replaced by -0-. In certain embodiments, L is -CH₂-. In certain embodiments, adhesive compositions of the present invention comprise one or more polymers of formula 8:

where R^z, E, GJ, k, and m are as defined above. In certain embodiments, adhesive compositions of the present invention comprise polymers of formula 9.

where E, GJ, k, and m are as defined above.

In certain embodiments, adhesive compositions of the present invention comprise one or more polymers of formula 10 or 11:

where E, G, j, k, and m are as defined above, each x is independently an integer between 0 and 4 inclusive, and each x' is independently an integer between 0 and 8 inclusive. As discussed above, provided compositions may be characterized by the percentage of carbonate and ether linkages in the polymer chains. This characteristic may also be expressed as the ratio ofj:k as shown in formulae 1 through 11. In certain embodiments, adhesive compositions of the present invention contain one or more APCs of any of formulae 1 through 11, where the value of/ is greater than the value of k. In certain embodiments, the value of/ is at least about 10 times greater than the value of k. In other embodiments, the value of/ is at least about 20 times greater than the value of k. In certain embodiments, the value of/ is at least about 50 times greater than the value of k. In other embodiments, the value of/ is at least about 100 times greater than the value of k. In certain embodiments, the value of k is 0. In some embodiments, a polymer composition is essentially free of £ repeating units (ether linkages).

In certain embodiments, adhesive compositions of the present invention contain one or more APCs of any of formulae 1 through 11, where the number average molecular weight (M_N) of the APC is in the range from about 1 x 10 g/mol to about 2 x 10 g/mol. In certain embodiments, M_N ranges from about 20,000 g/mol to about 400,000 g/mol. In certain embodiments, M_N ranges from about 80,000 g/mol to about 300,000 g/mol. In certain embodiments, M_N ranges from about 100,000 g/mol to about 300,000 g/mol.In certain embodiments, M_N ranges from about 150,000 g/mol to about 250,000 g/mol.

In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate).

In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a PDI of less than about 1.7. In some embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a PDI of between about 1.1 and about 1.5. In some embodiments, adhesive compositions of the present invention comprise poly (propylene carbonate) with a PDI of between about 1.2 and about 1.4. In some embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a PDI of less than about 1.2. In some embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a PDI of about 1.1.

In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 4: 1. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 5:1. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 10:1. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 100:1.

In certain embodiments, provided adhesive compositions comprising poly(propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 85% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 90% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 91% or greater. In certain embodiments, provided adhesive compositions comprising poly(propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 92% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 93% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 94% or greater. In certain embodiments, provided adhesive compositions comprising poly(propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 95% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 96% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is

97% or greater. In certain embodiments, provided adhesive compositions comprising poly(propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 98% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 99% or greater. In certain embodiments, provided adhesive compositions comprising poly (propylene carbonate) are characterized in that, on average in the composition, the percentage of carbonate linkages is 99.5% or greater. In certain embodiments, provided adhesive compositions comprising poly(propylene carbonate) are characterized in that ether linkages are not detectable by ¹H or ¹³C NMR.

It will be appreciated that where the present disclosure describes one characteristic of provided compositions, the disclosure encompasses compositions having such individual characteristics alone and in combination with one or more other characteristics as described herein. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) having a head-to-tail ratio of at least 4: 1, a PDI less than 1.5, an ether content of less than 10%, and a M_N between 75,000 g/mol and 350,000 g/mol. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) having a head-to-tail ratio of at least 9: 1, a PDI less than 1.5, an ether content of less than 10%, and a M_N between 75,000 g/mol and 350,000 g/mol. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) having a head-to-tail ratio of at least 6: 1, a PDI less than 1.4, an ether content of less than 10%, and a M_N between 75,000 g/mol and 350,000 g/mol. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) having a head-to-tail ratio of at least 4: 1, a PDI less than 1.4, an ether content of less than 10%, and a M_N between 75,000 g/mol and 350,000 g/mol. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) having a head-to-tail ratio of at least 4: 1, a PDI less than 1.5, an ether content of less than 5%, and a M_N between 75,000 g/mol and 350,000 g/mol. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) having a head-to-tail ratio of at least 20: 1, a PDI less than 1.3, an ether content of less than 2%, and a M_N between 75,000 g/mol and 350,000 g/mol.

In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) that shows less than about 10% loss of mass after aging at 180 ⁰C for 30 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) that shows less than about 10% loss of mass after aging at 180 ⁰C for 60 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) that shows less than about 10% loss of mass after aging at 180 ⁰C for 120 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly (propylene carbonate) that shows less than about 20% loss of mass after aging at 180 ⁰C for 180 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly (propylene carbonate) that shows less than about 20% loss of mass after aging at 180 ⁰C for 240 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) that shows less than about 10% loss of mass after aging at 200 ⁰C for 20 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) that shows less than about 10% loss of mass after aging at 200 ⁰C for 30 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly(propylene carbonate) that shows less than about 20% loss of mass after aging at 200 ⁰C for 30 minutes. In certain embodiments, adhesive compositions of the present invention comprise poly (propylene carbonate) that shows less than about 20% loss of mass after aging at 200 ⁰C for 50 minutes.

In certain embodiments, adhesive compositions of the present invention are characterized in that > 95% of the mass is retained at temperatures below a Td range and > 95% of the mass is lost at temperatures above the Td range. In certain embodiments, adhesive compositions of the present invention are characterized in that > 96% of the mass is retained at temperatures below a Td range and > 96% of the mass is lost at temperatures above the Td range. In certain embodiments, adhesive compositions of the present invention are characterized in that > 97% of the mass is retained at temperatures below a Td range and > 97% of the mass is lost at temperatures above the Td range. In certain embodiments, adhesive compositions of the present invention are characterized in that > 98% of the mass is retained at temperatures below a Td range and > 98% of the mass is lost at temperatures above the Td range. In certain embodiments, adhesive compositions of the present invention are characterized in that > 99% of the mass is retained at temperatures below a Td range and > 99% of the mass is lost at temperatures above the Td range.

In some embodiments, a Td range is less than about 50 Celsius degrees. In some embodiments, a Td range is less than about 30 Celsius degrees. In some embodiments, a Td range is less than about 20 Celsius degrees. In some embodiments, a Td range is less than about 15 Celsius degrees. In some embodiments, a Td range is less than about 12 Celsius degrees. In some embodiments, a Td range is less than about 11 Celsius degrees. In some embodiments, a Td range is less than about 10 Celsius degrees. In some embodiments, a Td range is less than about 5 Celsius degrees. In certain embodiments, adhesives of the present invention comprise random, block, or tapered copolymers of two or more of 1 through 11. In certain embodiments, adhesives of the present invention comprise copolymers of poly(propylene carbonate) and poly(cyclohexene carbonate).

1.2 Solutions of adhesives

In some embodiments, the present invention encompasses solutions of the above- described adhesive compositions suitable for coating semiconductor wafers, flexible substrates or rigid carriers for supporting either of these. In certain embodiments, the concentration of an adhesive composition in a solvent is adjusted to provide a viscosity suitable for spin-coating a solution onto a substrate.

Adhesive solutions of the present invention may include any solvent or mixture of solvents in which components of composition are soluble. In certain embodiments, solutions of the present invention comprise one or more of the following solvents: acetone, butanone, pentanone, hexanone, heptanone, gamma butyro lactone, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, aromatic hydrocarbons, halogenated aromatic hydrocarbons, tetrahydrofuran, and dimethoxy ethane. In certain embodiments, solutions of the present invention comprise acetone. In certain embodiments, solutions of the present invention comprise butanone. In certain embodiments, solutions of the present invention comprise 2- heptanone. In certain embodiments, solutions of the present invention comprise gamma butyrolactone. In certain embodiments, solutions of the present invention comprise toluene. In certain embodiments, solutions of the present invention comprise chlorobenzene. In certain embodiments, solutions of the present invention comprise xylene. In certain embodiments, solutions of the present invention comprise methyl isobutyl ketone.

In some embodiments, the concentration of adhesive composition in a solvent is adjusted so that the solvent to solute ratio is suitable for spin-coating a solution onto a substrate to yield a film of a desired thickness. 2. Methods of use

The present invention provides, among other things, methods for substrate processing. In certain embodiments, the present invention provides methods for wafer processing wherein a semiconductor wafer is temporarily bonded to a carrier substrate with a layer of adhesive comprising any one or more of the above-described adhesive compositions. In certain embodiments, the present invention encompasses methods for the processing or manufacture of flexible electronic assemblies wherein a flexible substrate is temporarily bonded to a rigid carrier substrate with a layer of adhesive comprising any one or more of the above-described adhesive compositions. In certain embodiments, the present invention encompasses methods relating to substrate processing in the areas of micro flui dies, optics, and microelectromechanical systems (MEMS).

2.1 Methods of substrate processing

In one aspect, the invention provides methods for fabricating electronic components and/or circuits on a substrate, comprising temporarily bonding a substrate to a rigid carrier and then fabricating electronic components and/or circuits on an exposed surface of a substrate. In some embodiments, the invention provides methods of forming a film comprising one of the above-described adhesive compositions on at least one of a rigid carrier and a substrate; and then bonding a substrate to a rigid carrier with the film positioned between the substrate and the rigid carrier.

In certain embodiments, the invention provides a method wherein forming a film of the adhesive composition on a rigid support or substrate is accomplished by forming a layer of a solution of the adhesive composition on the rigid carrier or the substrate, and drying the layer to form the film. In some embodiments, the rigid carrier is coated with a film of the adhesive composition of the invention. In certain embodiments, a solution of an adhesive composition comprises the adhesive composition dissolved in an appropriate solvent. An adhesive composition and solvent (or solvents) are combined and allowed to dissolve while agitating for a period of time. Heat may be applied to dissolve an adhesive composition provided the temperature is kept below the critical decomposition temperature of the adhesive composition. A solution of an adhesive composition may further comprise additives, such as nitrocellulose or ethylcellulose, to adjust the decomposition temperature of the adhesive composition film.

A film of an adhesive composition on a rigid carrier or substrate formed using a solution of the adhesive composition may be prepared according to any method known to those skilled in the art for preparing a film from a solution. For example, a solution may be spray coated, drop cast, spin coated, webcoated, doctor bladed, or dip coated to produce a layer of the solution on a carrier or a substrate. When a layer is formed on a rigid carrier, a solution can be spin coated by dispensing a solution on a surface of the rigid carrier and spinning the carrier to evenly distribute the solution.

One skilled in the art will understand that the thickness of a layer, and ultimately a film, produced by spin coating may be controlled by selection of the concentration of an adhesive composition in a solvent, the viscosity and/or solvent to solute ratio of a solution, and the spinning speed.

A solution layer may be dried prior to bonding of a substrate or rigid carrier to remove solvent and produce an adhesive composition film. This drying may be according to any method known to those skilled in the art provided the method does not cause deterioration of a substrate, a carrier, and/or an adhesive composition. For example, a layer may be dried by heating the layer at a temperature in the range of approximately 60⁰C to 180⁰C, and preferably, about 100 ⁰C to 130⁰C. In another example, a layer may be dried by heating the layer in a vacuum a temperature in the range of approximately 50⁰C to 180⁰C. In yet another example, a layer may be dried by heating the layer at a temperature in the range of approximately 80⁰C to 180⁰C, followed by heating the layer in a vacuum (e.g., less than about 1 torr) at temperature in the range of approximately 100⁰C to 180⁰C. In either heating process, a layer may be heated for about 10 to 120 minutes until substantially all solvent is removed. One skilled in the art will recognize that higher temperatures (e.g., up to 300⁰C) may be used in any of the heating steps provided the adhesive composition remains stable during heating.

In certain embodiments, an adhesive composition film is between about 1 μm and about 40 μm thick. In some embodiments, an adhesive film is between about 2 μm and about 20 μm thick. In some embodiments, an adhesive film is between about 20 nm and about 1 μm thick.

Alternatively, a layer of an adhesive composition solution may be coated onto the back side of a substrate, followed by a drying and/or vacuum drying process, as discussed previously, to produce an adhesive composition film on a substrate. In certain embodiments, when a film of an adhesive composition is formed on a substrate, a layer of a solution is produced by spin coating of the solution followed by drying of the layer to produce the film, as discussed previously. In certain embodiments, an adhesive composition film is applied to both a carrier and a substrate.

In certain methods of the invention, a freestanding substrate is bonded to the upper surface of adhesive composition film. Several different procedures can be used to bond a substrate to an adhesive composition film. In some embodiments, bonding a substrate comprises the steps of heating an adhesive composition film (either on the substrate or the rigid carrier) to a softened state, i.e. above the glass transition temperature (T_g) of the adhesive composition, and then attaching the substrate directly to a carrier. The specific softening temperature for use in the present invention can be readily determined empirically based on known techniques, and depends upon the specific material used in adhesive composition film. For example, T_g may be determined using techniques such as, but not limited to, thermogravimetric analysis (TGA), thermomechanical analysis (TMA), differential scanning calorimetry (DSC), and/or dynamic mechanical analysis (DMA). With a substrate temporarily attached to rigid carrier, all of the desired processing steps can be performed on the substrate to fabricate electronic circuits. As the final system may be approximately the same size as a substrate (i.e., a semiconductor wafer), standard processing tools may be used to perform fabrication. Once the desired electronic fabrication or processing steps are completed, removal of an adhesive composition film effects detachment of a substrate from a rigid carrier.

In certain embodiments, the invention provides methods wherein after fabrication, a substrate is detached from a rigid carrier; preferably, the substrate is detached by heating an adhesive composition film. In some embodiments, an adhesive composition is heated to and maintained at a temperature where the adhesive composition film decomposes. Such heating is preferably performed in air or an inert atmosphere (e.g. nitrogen). More preferably, such heating is performed in air. In certain embodiments, one or more steps of fabrication or heating are performed under vacuum.

Decomposition temperatures and duration of heating for adhesive compositions and films thereof of the instant invention can be readily determined utilizing methods known to those skilled in the art based on the teachings herein, for example, using thermo gravimetric analysis (TGA). As noted previously, other materials can be used in adhesive composition film to adjust the decomposition temperature. That is, the temperature at which an adhesive composition film is removed may be raised or lowered as necessary as required to maintain the stability of by the material of a substrate and/or compatibility with various electronic processing steps and materials.

Other processes may be used to affect removal of the adhesive composition film. For example, a flash lamp, an RTA (Rapid Thermal Anneal) process using a halogen lamp, infrared radiation, microwaves, or a laser may be used to decompose the adhesive composition film.

The decomposition can be either pyrolysis or combustion. For example, when poly(propylene carbonate) is used, an adhesive composition film may be removed at a temperature of at least 240 ⁰C, and preferably, between 240 ⁰C and 300 ⁰C; more preferably, between 240 ⁰C and 260⁰C.

In each of the preceding embodiments, an adhesive composition film comprises one or more poly(alkylene carbonate)s 1 through 11 as described above. An adhesive composition may further comprise any one or more materials selected from the group consisting of: nitrocellulose, ethylcellulose, poly(methyl methacrylate), poly( vinyl alcohol), poly(vinyl butyryl), poly(isobutylene), poly(vinyl pyrrolidone), micro crystalline celluloses, waxes, poly(lactic acid), poly(dioxanone), poly(hydroxybutyrate), poly(acrylate)s, poly(benzocyclobutene)s, and mixtures thereof.

In each of the preceding embodiments, a substrate can be a flexible substrate. In certain embodiments, a flexible substrate is a preformed flexible plastic substrate or a preformed flexible metal substrate. Suitable flexible metal substrates include FeNi alloys (e.g., INVARTM, FeNi, or FeNi36; INVARTM is an alloy of iron (64%) and nickel (36%) (by weight) with some carbon and chromium), FeNiCo alloys (e.g., KOVAR™, KOVAR™ is typically composed of 29% nickel, 17% cobalt, 0.2% silicon, 0.3% manganese, and 53.5% iron (by weight)), titanium, tantalum, molybdenum, aluchrome, aluminum, and stainless steel. Suitable flexible plastic substrates include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethersulfone (PES), polyimide, polycarbonate, and cyclic olefin copolymer.

Such flexible substrates are preferably thin; preferably, about 1 μm to 1 mm thick. In some embodiments, a flexible substrate is about 50 μm to about 500 μm. In some embodiments, a flexible substrate is about 50 μm to about 250 μm. In each of the preceding embodiments, a rigid carrier comprises any material that is capable of withstanding the processing used to fabricate electronic components or circuits. Preferably, a rigid carrier comprises a semiconducting material.

In some embodiments, a rigid carrier preferably has at least one substantially flat surface. In certain embodiments, a rigid carrier is a semiconductor wafer. In some embodiments, a rigid carrier is a silicon wafer with a flat surface. In some embodiments, a carrier is selected based upon its coefficient of thermal expansion CTE) (e.g., a material with a CTE « a CTE of a substrate).

In some embodiments, the invention provides methods for fabricating electronic components and/or circuits on a semiconductor substrate comprising the step of temporarily attaching a first face of a semiconductor wafer to the surface of a rigid carrier with any adhesive compositions described hereinabove. In certain embodiments, the head-to-tail ratio of the PPC in an adhesive composition is greater than about 4:1. In one aspect, the adhesive composition comprises an aliphatic polycarbonate having a PDI of less than about 1.7. In certain aspects an adhesive composition comprises PPC having a PDI less than about 1.5. In certain embodiments, an adhesive composition comprises PPC having a number average molecular weight between about 50,000 g/mol and 300,000 g/mol. In certain embodiments, PPC in an adhesive composition has less than about 10% ether linkages. In certain embodiments, PPC in an adhesive composition demonstrates less than 20% loss of mass after aging for 2 hours at 180 ⁰C.

In some embodiments, provided methods further comprise backgrinding the second face of a semiconductor substrate to decrease the thickness of the semiconductor substrate. In some embodiments, backgrinding comprises mechanical grinding, chemical-mechanical polishing, and/or wet etching. In certain embodiments, methods further comprise backgrinding the second face of a semiconductor substrate to decrease the thickness of the semiconductor substrate; and heating an assembly to decompose the adhesive layer thereby detaching the semiconductor substrate from a rigid carrier.

In certain embodiments, an adhesive composition may placed either on the first face of the semiconductor substrate or on a rigid carrier or both. The adhesive layer can be produced according to any of the methods discussed previously with respect to the bonding of substrates. In some embodiments, a rigid carrier may comprise a semiconductor substrate or glass. In certain embodiments, a rigid carrier comprises Si or Si(IOO). Any semiconductor substrate utilized in methods of a second aspect may independently comprise Si, SiGe, Ge, SiGeSn, GeSn, GaAs, InP, and the like.

In some embodiments of the present invention, any semiconductor substrate utilized in provided methods may independently comprise Si or Si(IOO). In certain embodiments, an adhesive composition comprises poly(propylene carbonate) having a PDI of less than 1.7. An adhesive composition film may comprise additives, such as nitrocellulose or ethylcellulose, to adjust the decomposition temperature of an adhesive composition film.

2.2 Additional methods and uses

As stated above, an inventive adhesive can be used in various additional methods relating to substrate processing in the areas of micro flui dies, optics, and microelectromechanical systems (MEMS). In the field of wafer processing, compositions of adhesive can be applied to the backside of a substrate to be processed and/or the supporting surface of a carrier so that the substrate can be temporarily bonded to the carrier. A carrier can be used to hold a substrate during a precision processing step, e.g., chemical mechanical polishing (CMP), substrate inspection, or lithographic patterning processes such as ion beam lithography, electron beam lithography, projection optical photolithography, contact photolithography, nano-imprint lithography. In each application, the adhesive can firmly hold the substrate with respect to the carrier to prevent slipping of the substrate during the processing step. The prevention of slippage can be particularly important for inspection and lithographic patterning steps where precise and accurate locations on the substrate may need to be determined. In a CMP step, it may be desired to planarize the surface of the substrate. The inventive adhesive can firmly and temporarily hold the substrate to a flat carrier so that the device-side surface can be planarized in the CMP step.

For substrate inspection or lithographic patterning, an adhesive can be applied as noted above to firmly and temporarily support the substrate on a carrier. A carrier can comprise a component attached to or attachable to a precision translation stage. A bonding process can be as described elsewhere herein. A temporary bond between a substrate and carrier can prevent slippages of the substrate with respect to the carrier during an inspection step or patterning step. Such slippages can occur in traditional systems due to accelerations and decelerations of a translation stage upon which a carrier can be mounted.

Certain embodiments of adhesive compositions can be used in micro fluidics to temporarily bond a cover to a substrate having microfluidic channels. A substrate can comprise plural microfluidic channels etched or patterned into a surface of a substrate, e.g., into a quartz, fused silica, or polymer substrate. In certain embodiments, a planar-shaped cover must be bonded to a substrate to complete formation of plural microfluidic lumens. A composition of an adhesive can be applied to a planar-shaped cover, and the cover can be firmly and temporarily bonded to a substrate to form one or more microfluidic devices. A bonding step can be as described elsewhere herein. In such embodiments, bonding can form a leak-proof seal such that fluid flowing in microfluidic channels cannot leak into small gaps between a cover and substrate having microfluidic channels. Small gaps can occur when a cover is not bonded to a substrate. Additionally, a cover and substrate can be separated by applying heat to a device, so that microfluidic channels and cover can be readily cleaned. A substrate having microfluidic channels can then be reused many times.

In the field of precision optics, compositions of an adhesive can be used to temporarily and firmly hold an optical substrate to a carrier during a processing step, e.g., grinding or optical polishing. An inventive adhesive composition can be applied to a carrier and/or an optical substrate, so that the optical substrate can be bonded to the carrier. A bonding step can be as described elsewhere herein. In certain embodiments, an adhesive bonds and protects a bound surface of an optical component. For example, a first surface of an optical flat or lens can be polished to a high degree of flatness and smoothness. The first surface, now finished, can then be coated with a film of the adhesive and bonded to a carrier. The adhesive protects the first finished surface from particulates that can be generated during finishing of a second surface, and temporarily binds the optic to the carrier. After finishing the second surface, the optic can be readily removed by the application of heat. Inventive compositions of the adhesive can be used to temporarily bond components in MEMS or integrated optical devices. The MEMS or integrated optical device can comprise a microchip having circuits, waveguides, device elements and/or micromechanical structures. For prototyping, or producing a finished device in some embodiments, an inventive adhesive can be applied to a component of a MEMS device or integrated optical device, so that the component can be aligned or properly located on the device and bonded thereto. An advantage of provided adhesive compositions is that the bonding step can be extended for a length of time sufficient to align or position the component, and then substantially immediately completed. As an example, in an integrated optical device, it may be necessary to align an integrated optical chip to a waveguide or optical fiber. An adhesive can be applied so as to bond either a chip or waveguide to an aligned position. An adhesive can be heated above its T_g so that the two components can be properly aligned. Once proper alignment is detected, the temperature of an adhesive can be lowered to substantially immediately affect a physical bond.

It is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.

Claims

CLAIMSWhat is claimed is:

1. A method for processing a substrate comprising bonding the substrate to a rigid carrier with an adhesive composition, wherein the adhesive composition comprises a polycarbonate of formula 1:

wherein,

R^a is hydrogen, halogen, -L-OR^Z, or an optionally substituted moiety selected from the group consisting Of C_1-30 aliphatic; 3- to 14-membered carbocycle; 6- to 14- membered aryl; 5- to 14-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; or R^a is an optionally substituted C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain, wherein one or more methylene units are optionally and independently replaced by -NR-, - N(R)C(O)-, -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -O-, -C(O)-, -OC(O)-, -OC(O)O- , -C(O)O-, -OC(O)N(R)-, -S-, -SO-, -SO₂-, -C(=S)-, or -C(=NR)-, and where one or more hydrogen atoms is optionally replaced with -OR^Z;

L is a C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain;

each R is independently hydrogen, optionally substituted C_1-6 aliphatic, or: two R on the same nitrogen atom are taken together with the nitrogen atom to form a 4- to 7-membered heterocyclic ring having 0-2 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur;

wherein any of (R^a and R^c), (R^c and R^d), and (R^a and R^b) can be taken together with their intervening atoms to form one or more optionally substituted rings selected from the group consisting of: 3- to 14-membered carbocycle; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

E is any group that can ring-open an epoxide; G is selected from the group consisting of hydrogen, a C_1-20 acyl group, a silyl group, an optionally substituted C_1-20 aliphatic group, an optionally substituted 6- to 14- membered aryl group, a carbamoyl group, and a hydroxyl protecting group; j is an integer from about 90 to about 15,000; k is an integer from about 0 to about 2,500; and m is the sum of j and k, wherein m is an integer from about 100 to about 17,500.

2. The method of claim 1, wherein the aliphatic carbonate of the adhesive composition has a head-to-tail ratio greater than about 4: 1.

3. The method of claim 1, wherein the aliphatic carbonate of the adhesive composition has a PDI of less than 1.7.

4. The method of claim 2, wherein the aliphatic carbonate of the adhesive composition has a PDI of less than 1.7.

5. The method of any one of claims 1-4, wherein the aliphatic carbonate of the adhesive composition is characterized in that, on average in the composition, the percentage of carbonate linkages is 95% or greater.

6. The method of claim 1, wherein the polycarbonate has the formula:

7. The method of claim 1, further comprising the steps of heating the adhesive to a temperature above the T_d(onset) of the polycarbonate and removing the substrate from the carrier.

8. The method of claim 1 , further comprising optically grinding or polishing the substrate, wherein the substrate comprises a precision optical component.

9. The method of claim 1, wherein the carrier holds the substrate during a substrate processing step of chemical mechanical polishing.

10. The method of claim 1, wherein the carrier holds the substrate during a substrate processing step of substrate inspection such that there is substantially no slippage of the substrate with respect to the carrier during substrate inspection.

11. The method of claim 1 , wherein the carrier holds the substrate during a substrate processing step of lithographic patterning such that there is substantially no slippage of the substrate with respect to the carrier during lithographic patterning.

12. The method of claim 1, wherein the polycarbonate is poly (propylene carbonate) having a PDI of less than 1.5.

13. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a PDI of less than 1.2.

14. The method of claim 1, wherein the polycarbonate is poly (propylene carbonate) having a head-to-tail ratio greater than about 5: 1.

15. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a head-to-tail ratio greater than about 10:1.

16. The method of claim 1, wherein the polycarbonate is poly (propylene carbonate) having a head-to-tail ratio greater than about 20: 1.

17. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a head-to-tail ratio greater than about 50: 1.

18. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a head-to-tail ratio greater than about 100: 1.

19. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) characterized in that it loses less than 10% of its mass when held at a temperature of 180 ⁰C for 120 minutes.

20. The method of claim 19, wherein the poly (propylene carbonate) has an M_N between about 100,000 g/mol and about 300,000 g/mol.

21. The method of claim 1 , wherein the polycarbonate is poly (propylene carbonate) characterized in that it loses less than 10% of its mass when held at a temperature of 200 ⁰C for 30 minutes.

22. The method of claim 1 , wherein the polycarbonate is poly(propylene carbonate) having M_N between about 50,000 g/mol and about 400,000 g/mol.

23. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a

PDI of less than about 1.7.

24. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a PDI of less than about 1.5.

25. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a PDI of less than about 1.2

26. The method of claim 1, wherein the polycarbonate is a copolymer of poly(propylene carbonate) and poly(cyclohexene carbonate).

27. The method of claim 1 , wherein the polycarbonate is poly (propylene carbonate) and the ratio of/ to k is greater than 10:1.

28. The method of claim 1 , wherein the polycarbonate is poly (propylene carbonate) and the ratio of/ to k is greater than 20: 1.

29. The method of claim 1 , wherein the polycarbonate is poly (propylene carbonate) and the ratio of/ to k is greater than 50: 1.

30. The method of claim 1 , wherein the polycarbonate is poly (propylene carbonate) and the ratio of/ to k is greater than 100: 1.

31. The method of claim 1, wherein the polycarbonate is poly(propylene carbonate) having a PDI less than 1.2, M_N between 50,000 and 350,000, and a head to tail ratio of at least 4:1, wherein the ratio of/ to k is at least 20: 1, characterized in that it loses less than 10% of its mass on aging at 180 ⁰C for 3 hours.

32. The method of claim 1, wherein the adhesive composition is characterized in that > 95% of the mass is retained at temperatures below a Td range and > 95% of the mass is lost at temperatures above the Td range.

33. The method of claim 32, wherein the Td range is less than about 30 Celsius degrees.

34. The method of claim 32, wherein the Td range is less than about 15 Celsius degrees.

35. The method of claim 32, wherein the Td range is less than about 12 Celsius degrees.

36. The method of claim 1, wherein the adhesive composition is characterized in that Td(5%) is from about 218 ⁰C to about 224 ⁰C.

37. The method of claim 1, wherein the adhesive composition is characterized in that Td(95%) is from about 229 ⁰C to about 235 ⁰C.

38. A method for bonding a component to a MEMS device or integrated optical device, comprising the steps of: applying an amount of adhesive composition to one or both of the component and

MEMS or integrated optical device; placing the component in contact with the MEMS or integrated optical device; and heating the component and/or MEMS or integrated optical device so as to raise the temperature of the adhesive composition above T_g; aligning the component with respect to the MEMS or integrated optical device; and lowering the temperature of the adhesive composition below T_g so as to effect a bond between the component and MEMS or integrated optical device;

wherein the adhesive composition comprises a polycarbonate of formula 1:

wherein,

R^a is hydrogen, halogen, -L-OR^Z, or an optionally substituted moiety selected from the group consisting of Ci-30 aliphatic; 3- to 14-membered carbocycle; 6- to 14- membered aryl; 5- to 14-membered heteroaryl having 1 -4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; or R^a is an optionally substituted Ci_₈ saturated or unsaturated, straight or branched, hydrocarbon chain, wherein one or more methylene units are optionally and independently replaced by -NR-, - N(R)C(O)-, -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -O-, -C(O)-, -OC(O)-, -OC(O)O- , -C(O)O-, -OC(O)N(R)-, -S-, -SO-, -SO₂-, -C(=S)-, or -C(=NR)-, and where one or more hydrogen atoms is optionally replaced with -OR^Z; L is a Ci_8 saturated or unsaturated, straight or branched, hydrocarbon chain;

each R is independently hydrogen, optionally substituted C_1-6 aliphatic, or:

two R on the same nitrogen atom are taken together with the nitrogen atom to form a

4- to 7-membered heterocyclic ring having 0-2 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur;

each of R^b, R^c, and R^d is independently hydrogen, halogen, or an optionally substituted group selected from the group consisting of C_1-12 aliphatic; C_1-12 heteroaliphatic having 1 -4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 3- to 14-membered carbocycle; 6- to 14-membered aryl; 5- to 14-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

E is any group that can ring-open an epoxide; G is selected from the group consisting of hydrogen, a C_1-20 acyl group, a silyl group, an optionally substituted Ci_₂o aliphatic group, an optionally substituted 6- to 14- membered aryl group, a carbamoyl group, and a hydroxyl protecting group; j is an integer from about 90 to about 15,000; k is an integer from about 0 to about 2,500; and m is the sum of j and k, wherein m is an integer from about 100 to about 17,500.

39. The method of 38 further comprising the steps of: testing the MEMS or integrated optical device; and heating the component and/or MEMS or integrated optical device so as to raise the temperature of the adhesive composition above Td.

40. A method for temporarily bonding a planar cover to a substrate having microfluidic channels comprising the steps of: applying a film of adhesive composition to the planar cover; placing the cover in contact with the substrate; and heating the cover or substrate to effect a bond between the cover and substrate, wherein the adhesive composition comprises a polycarbonate of formula 1:

wherein, R^a is hydrogen, halogen, -L-OR^Z, or an optionally substituted moiety selected from the group consisting of Ci_₃o aliphatic; 3- to 14-membered carbocycle; 6- to 14- membered aryl; 5- to 14-membered heteroaryl having 1 -4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; or R^a is an optionally substituted C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain, wherein one or more methylene units are optionally and independently replaced by -NR-, - N(R)C(O)-, -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -O-, -C(O)-, -OC(O)-, -OC(O)O- , -C(O)O-, -OC(O)N(R)-, -S-, -SO-, -SO₂-, -C(=S)-, or -C(=NR)-, and where one or more hydrogen atoms is optionally replaced with -OR^Z;

L is a C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain;

each R is independently hydrogen, optionally substituted C_1-6 aliphatic, or:

wherein any of (R^a and R°), (R⁰ and R^d), and (R^a and R^b) can be taken together with their intervening atoms to form one or more optionally substituted rings selected from the group consisting of: 3- to 14-membered carbocycle; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; E is any group that can ring-open an epoxide;

G is selected from the group consisting of hydrogen, a C_1-20 acyl group, a silyl group, an optionally substituted C_1-20 aliphatic group, an optionally substituted 6- to 14- membered aryl group, a carbamoyl group, and a hydroxyl protecting group; j is an integer from about 90 to about 15,000; k is an integer from about 0 to about 2,500; and m is the sum of j and k, wherein m is an integer from about 100 to about 17,500.

41. The method of 40, further comprising: heating the cover or substrate to a temperature greater than about Td; and removing the cover from the substrate.

42. The method of any one of claims 1-4 or 6-41, wherein the substrate is a semiconductor wafer.

43. The method of any one of claims 1-4 or 6-41, wherein the substrate is a flexible substrate.

44. An adhesive composition for bonding substrates comprising one or more aliphatic polycarbonates of formula 1:

wherein,

R^a is hydrogen, halogen, -L-OR^Z, or an optionally substituted moiety selected from the group consisting Of C_1-30 aliphatic; 3- to 14-membered carbocycle; 6- to 14- membered aryl; 5- to 14-membered heteroaryl having 1 -4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; or R^a is an optionally substituted C_1-8 saturated or unsaturated, straight or branched, hydrocarbon chain, wherein one or more methylene units are optionally and independently replaced by -NR-, - N(R)C(O)-, -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -O-, -C(O)-, -OC(O)-, -OC(O)O- , -C(O)O-, -OC(O)N(R)-, -S-, -SO-, -SO₂-, -C(=S)-, or -C(=NR)-, and where one or more hydrogen atoms is optionally replaced with -OR^Z;

L is a Ci_8 saturated or unsaturated, straight or branched, hydrocarbon chain;

each R is independently hydrogen, optionally substituted C_1-6 aliphatic, or:

two R on the same nitrogen atom are taken together with the nitrogen atom to form a 4- to 7-membered heterocyclic ring having 0-2 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur; each R^z is independently selected from the group consisting of hydrogen, a silyl group, a hydroxyl protecting group, or an optionally substituted group selected from the group consisting of C_1-20 acyl; C_1-20 aliphatic; 3- to 14-membered carbocycle; 6- to 14-membered aryl; 5- to 14-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

each of R^b, R°, and R^d is independently hydrogen, halogen, or an optionally substituted group selected from the group consisting of C_1-12 aliphatic; C_1-12 heteroaliphatic having 1 -4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 3- to 14-membered carbocycle; 6- to 14-membered aryl; 5- to 14-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;

E is any group that can ring-open an epoxide;

45. The adhesive composition of claim 44, wherein the polycarbonate has formula Ia:

46. The adhesive composition of claim 44, wherein the polycarbonate has formula 2:

47. The adhesive composition of claim 44, wherein the polycarbonate has formula 3:

48. The adhesive composition of claim 44, wherein the polycarbonate has formula 3a:

49. The adhesive composition of claim 46, wherein R^a is selected from the group consisting of -H, methyl, ethyl, propyl, butyl, higher saturated aliphatic, chloromethyl, trifluoromethyl, pentafluoro ethyl, higher fluoroalkyl, vinyl, allyl, phenyl, benzyl, higher unsaturated aliphatic, and CH₂OR².

50. The adhesive composition of claim 46, wherein R^a is selected from the group consisting of -H, methyl, ethyl, propyl, butyl, C₅-₃₀ alkyl, chloromethyl, trifluoromethyl, pentafiuoroethyl, vinyl, allyl, phenyl, benzyl, CH₂OAc, CH₂OC(O)CF₃, CH₂OC(O)Et, CH₂OBz, CH₂OMe, CH₂OEt, CH₂OPr, CH₂OBu, CH₂OPh, CH₂OBn, CH₂OAUyI, and CH₂OCF₃.

51. The adhesive composition of any one of claims 46, 49, or 50, wherein the adhesive composition comprises a random-, tapered-, or block-copolymer comprising two or more monomer units having different R^a groups.

52. The adhesive composition of claim 44, wherein the polycarbonate has formula 4.

53. The adhesive composition of claim 44, wherein the polycarbonate has formula 5.

where R^f is independently an optionally substituted C_1-10 aliphatic group, and x is an integer between 0 and 5 inclusive.

54. The adhesive composition of claim 44, wherein the polycarbonate has formula 6.

55. The adhesive composition of claim 44, wherein the polycarbonate has formula 7.

56. The adhesive composition of claim 44, wherein the polycarbonate has formula 8.

57. The adhesive composition of claim 44, wherein the polycarbonate has formula 9:

58. The adhesive composition of claim 44, wherein the polycarbonate has formula 10:

wherein each x is independently an integer between 0 and 4 inclusive.

59. The adhesive composition of claim 44, wherein the polycarbonate has formula 11:

wherein each x' is independently an integer between 0 and 8 inclusive.

60. The adhesive composition of claim 44, wherein the value of/ is greater than the value of k.

61. The adhesive composition of claim 44, wherein the value of/ is at least 10 times greater than the value of k.

62. The adhesive composition of claim 44, wherein the value of/ is at least 20 times greater than the value of k.

63. The adhesive composition of claim 44, wherein the value of/ is at least 50 times greater than the value of k.

64. The adhesive composition of claim 44, wherein the value of k is 0.

65. The adhesive composition of claim 44, wherein the composition is essentially free of k repeating units.

66. The adhesive composition of claim 44, wherein a number average molecular weight (M_N) of the polycarbonate is in the range from about 1 x 10 g/mol to about 2 x 10 g/mol.

67. The adhesive composition of claim 66, wherein the M_N ranges from about 50,000 g/mol to about 400,000 g/mol.

68. The adhesive composition of claim 66, wherein the M_N ranges from about 100,000 g/mol to about 300,000 g/mol.

69. The adhesive composition of claim 66, wherein the M_N ranges from about 150,000 g/mol to about 250,000 g/mol.

70. The adhesive composition of claim 44, wherein the polycarbonate comprises poly (propylene carbonate) with a PDI between about 1.1 and about 1.5.

71. The adhesive composition of claim 44, wherein the polycarbonate comprises poly (propylene carbonate) with a PDI between about 1.2 and about 1.4.

72. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) with a PDI of about 1.2.

73. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) with a PDI of about 1.1.

74. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 4: 1.

75. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 5:1.

76. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 10: 1.

77. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) with a head to tail ratio (H:T) greater than about 100: 1.

78. The adhesive composition of claim 44, wherein the polycarbonate comprises poly (propylene carbonate) having a PDI less than 1.5, an ether content of less than 10%, a head-to-tail ratio of at least 4:1, and M_N between 75,000 g/mol and 350,000 g/mol.

79. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 10% loss of mass after aging at 180 ⁰C for 60 minutes.

80. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 10% loss of mass after aging at 180 ⁰C for 120 minutes.

81. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 20% loss of mass after aging at 180 ⁰C for 240 minutes.

82. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 10% loss of mass after aging at 200 ⁰C for 20 minutes.

83. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 10% loss of mass after aging at 200 ⁰C for 30 minutes.

84. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 20% loss of mass after aging at 200 ⁰C for 30 minutes.

85. The adhesive composition of claim 44, wherein the polycarbonate comprises poly(propylene carbonate) characterized in that it shows less than about 20% loss of mass after aging at 200 ⁰C for 50 minutes.

86. The adhesive composition of claim 44, wherein the polycarbonate comprises a copolymer of poly (propylene carbonate) and poly(cyclohexene carbonate).

87. The adhesive composition of claim 44, characterized in that > 95% of the mass is retained at temperatures below a T_d range and > 95% of the mass is lost at temperatures above the T_d range.

88. The adhesive composition of claim 87, wherein the Td range is less than about 30 Celsius degrees.

89. The adhesive composition of claim 87, wherein the Td range is less than about 15 Celsius degrees.

90. The adhesive composition of claim 87, wherein the Td range is less than about 12 Celsius degrees.

91. The adhesive composition of claim 44, wherein T_d(5%) is from about 218 ⁰C to about 224 ⁰C.

92. The adhesive composition of claim 44, wherein T_d(95%) is from about 229 ⁰C to about 235 ⁰C.

93. A solution of an adhesive composition for bonding substrates comprising: one or more aliphatic polycarbonates of formula 1:

and a solvent selected from the group consisting of: acetone, butanone, pentanone, hexanone, heptanone, gamma butyrolactone, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, aromatic hydrocarbons, halogenated aromatic hydrocarbons, tetrahydrofuran, and dimethoxy ethane, and mixtures of two or more of these, wherein,

R^a is hydrogen, halogen, -L-OR^Z, or an optionally substituted moiety selected from the group consisting Of C_1-30 aliphatic; 3- to 14-membered carbocycle; 6- to 14- membered aryl; 5- to 14-membered heteroaryl having 1 -4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 3- to 12-membered heterocyclic having 1-3 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; or R^a is an optionally substituted Ci_₈ saturated or unsaturated, straight or branched, hydrocarbon chain, wherein one or more methylene units are optionally and independently replaced by -NR-, - N(R)C(O)-, -C(O)N(R)-, -N(R)SO₂-, -SO₂N(R)-, -O-, -C(O)-, -OC(O)-, -OC(O)O- , -C(O)O-, -OC(O)N(R)-, -S-, -SO-, -SO₂-, -C(=S)-, or -C(=NR)-, and where one or more hydrogen atoms is optionally replaced with -OR^Z;

L is a Ci_8 saturated or unsaturated, straight or branched, hydrocarbon chain;

94. The solution of claim 93, wherein the viscosity of the solution is suitable for spin-coating the solution onto a substrate to yield a film of a desired thickness.

95. The solution of claim 93, wherein the solvent to solute ratio is suitable for spin-coating the solution onto a substrate to yield a film of a desired thickness.

96. The solution of claim 93, wherein the solvent comprises acetone.

97. The solution of claim 93, wherein the solvent comprises butanone.

98. The solution of claim 93, wherein the solvent comprises gamma butyrolactone.

99. The solution of claim 93, wherein the solvent comprises 2-heptanone.