HK1066066A - Polymers blends and their use in photoresist compositions for microlithography - Google Patents

Description

Polymer blends and their use in photoresist compositions for microlithography

Technical Field

The present invention relates to photoimaging, and in particular, to imaging in the manufacture of semiconductor devices using photoresists (positive and/or negative). The invention also relates to blends of polymer compositions having high UV transparency, particularly at short wavelengths, such as 157nm, which are useful as binder resins in photoresists and potentially in a wide variety of other applications.

Background

Polymeric products are used as components of imaging and photosensitive systems, particularly in photoimaging systems, such as l.f. thompson c.g. willson and m.j. bowden inMicro-meter Fine theory of lithography( Introduction to Microlithograpy2nd Edition, American Chemical Society, Washington, DC, 1994). In these systems, Ultraviolet (UV) light or other electromagnetic radiation impinges on a material containing a photoactive component, causing a physical or chemical change in the material. This produces a useful or latent image that can be processed into an image useful in the fabrication of semiconductor devices.

While the polymer product itself may be photoactive, typically the photosensitive composition will contain one or more photoactive components in addition to the polymer product. Upon exposure to electromagnetic radiation (e.g., UV light), the photoactive component acts to change the rheological state, solubility, surface properties, refractive index, color, electromagnetic properties, or other physical or chemical properties of the photosensitive composition as described in the above-mentioned monographs, such as Thompson, et al.

Electromagnetic radiation in the extreme ultraviolet or extreme ultraviolet region is required to image very fine features in semiconductor devices at the submicron level. For the manufacture of semiconductor devices, positive photoresists are generally used. UV lithography with 365nm (I-line) light using novolak polymers and diazonaphthoquinones as dissolution inhibitors is currently established chip technology with resolution limits of about 0.35-0.30 microns. Photolithography with p-hydroxystyrene polymers in the extreme ultraviolet region at 248nm is a known technique with a resolution limit of 0.35-0.18 nm. Since the lower resolution limit decreases with decreasing wavelength (i.e., resolution limit of 0.18-0.12 microns for 193nm imaging and about 0.07 microns for 157nm imaging), future lithographic processes are strongly driven to proceed at shorter wavelengths. Photolithography using 193nm exposure wavelength (obtained from an Ar-F excimer laser) is the first choice for future microelectronic fabrication with 0.18 and 0.13 μm design dimensions. Photolithography with 157nm exposure wavelength (obtained from a fluorine excimer laser) is the first choice for future microlithography to be much longer (after 193 nm), provided that suitable materials with sufficient transparency and other desirable properties at this very short wavelength can be found. The opacity of conventional near-UV and far-UV organic photoresists at 193nm or shorter wavelengths prevents their use at such short wavelengths in a single layer.

Some photoresist compositions are known to be suitable for imaging at 193 nm. For example, photoresist compositions containing cyclic olefin-maleic anhydride alternating copolymers have been shown to be useful for semiconductor imaging at 193nm (see F. Houlihan et al, Macromolecules, 30, P.6517-6534 (1997); T.Wallow et al, SPIE,2724p.355-364; and F.M. Houlihan et al, Journal of photopolymer Science and Technology,10no.3, P.511-520 (1997)). Several documents focus on the study of 193nm photoresists (u.oronoanyanwu et al, SPIE,3049p.92-103; allen et al, SPIE,2724p.334-343; and Semiconductor International, 9 months 1997, p.74-80). Compositions containing addition polymers of functionalized norbornene and/or ROMP (ring opening metathesis polymers) have been disclosed (e.g., to b.f. goodrich and PCT WO97/33198 (9/12/97)). Homopolymers of norbornadiene and maleic anhydride copolymers and their use in 193nm lithography are also reported (j.niu and j.frechet.angelw.chem.int.ed.,37no.5(1998), P.667-670). Copolymers of fluorinated alcohol-substituted polycyclic ethylenically unsaturated comonomers with sulfur dioxide suitable for 193nm lithography have been reported (see H.Ito et al, "Synthesis and evaluation of alicyclic backbone polymers for 193nm lithography"(Synthesis and Evaluation of Alicyclobacillus Polymer for 193nm Lithology), Chapter 16, ACS symposium series 706(Micro-and Nanopatterning Polymers) p.208-223(1998), and H.Ito et al, Abstract in Polymeric Materials science and Engineering Division, ACS Meeting, Vol.77Autumn meeting, 8-11 days 9 months 1997, Las-vegas.n.v.). Because of the presence of repeat units derived from sulfur dioxide in such alternating copolymers, it is not suitable for 157nm lithography because of its too high absorption coefficient at 157 nm.

Photoresists containing a fluorinated alcohol functional group attached to an aromatic moiety have been reported (see K.J. Przybila et al, "Hexafluoroacetate in Chemistry: AVERATE New Concept for Materials for Deep UV Lithography", SPIE1672(1992) P.500-512). These photoresists, while suitable for 248nm lithography because they contain aromatic functional groups, are not suitable for 193 or 157nm lithography because the absorption coefficient of the aromatic photoresist components is too high at these wavelengths.

Copolymers of fluoroolefin monomers and cyclic unsaturated monomers are known (U.S. Pat. Nos. 5,177,166 and 5,229,473, Daikin Industries, Ltd.). These patents do not mention the use of these copolymers in any photosensitive composition. Copolymers of certain fluorinated olefins with vinyl esters are known. For example, copolymers of TFE with cyclohexane carboxylic acid esters, vinyl esters are known (Japanese patent application JP 03281664, Dainippon Ink and Chemicals). Copolymers of TFE and vinyl esters (e.g., vinyl acetate) and the use of these copolymers in photosensitive compositions for refractive index imaging (e.g., holographic imaging) have also been reported (U.S. patent 4,963,471, Dupont).

Copolymers of norbornene-type monomers containing functional groups have been previously reported (WO/56837, b.f. goodrich), and copolymers of norbornene-type monomers containing functional groups with vinyl ethers, dienes and isobutenes (US5,677,405, b.f. goodrich).

Some copolymers of fluorinated alcohol comonomers with other comonomers are reported in U.S. patent 3,444,148 and JP 62186907 a2 patent publications. None of these patents relate to films or other non-photosensitive films or fibers, and do not mention the use of fluorinated alcohol comonomers in photosensitive layers (e.g., photoresists).

U.S. patent 5,655,627 discloses a method of producing a negative photoresist image by coating a solution of pentafluoropropyl methacrylate-t-butyl methacrylate copolymer photoresist in a solvent on a silicon wafer, then exposing at 193nm and developing with a carbon dioxide critical fluid.

There remains a need for photoresist compositions that meet a number of requirements for single layer photoresists, including optical clarity at 193nm and/or 157nm, plasma etch resistance, and solubility in aqueous-based alkaline developers.

Summary of The Invention

In a first aspect, the present invention provides a photoresist composition comprising:

(A) at least two polymers selected from:

(a) a fluorine-containing copolymer comprising a repeating unit derived from at least one ethylenically unsaturated compound, wherein the at least one ethylenically unsaturated compound is a polycyclic compound;

(b) a branched polymer comprising protected acidic groups, the polymer comprising one or more branching segments chemically bonded to a linear backbone segment;

(c) a fluoropolymer comprising at least one fluoroalcohol group having the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atomsOr together are (CF)₂)_nWherein n is 2 to about 10;

(d) perfluoro (2, 2-dimethyl-1, 3-dioxole) or CX₂＝CY₂Wherein X ═ F or CF₃Y ═ H, or perfluoro (2, 2-dimethyl-1, 3-dioxole) with CX₂＝CY₂The amorphous vinyl copolymer of (a); and

(e) nitrile/fluoroalcohol-containing polymers prepared from substituted or unsubstituted vinyl ethers; and

(B) at least one photoactive component. Typically, the absorption coefficient of the polymer in the blend at 157nm is less than 5.0 μm^-1。

In a second aspect, the present invention provides a method of preparing a photoresist image on a substrate, comprising, in order:

(X) imagewise exposing the photoresist layer to form an imaged region and a non-imaged region, wherein the photoresist layer is prepared from a photoresist composition comprising:

(A) at least two polymers selected from the above (a) to (e); and

(B) a photoactive component; and

(Y) developing the exposed photoresist layer with imaged areas and non-imaged areas to form a relief image on the substrate.

Detailed description of the preferred embodiments

A photoresist element comprising a substrate and at least one photoresist layer, wherein the photoresist layer is prepared from a photoresist composition comprising:

(A) at least two polymers selected from (a) to (e); and

(B) a photoactive component.

The polymer can be used in photoresist compositions used in semiconductor lithography. In particular, because one of the main features of the substances of the invention is the low absorption of light below 193nm, they are particularly useful at this wavelength. The absorption coefficient of these polymers at a wavelength of about 157nm is not required to be less than, but may be less than about 5.0 μm^-1Typically less than about 4.0 μm at this wavelength^-1And more typically less than about 3.5 μm^-1。

Polymer and method of making same

The fluoropolymer (a) comprises a repeating unit derived from at least one ethylenically unsaturated compound, characterized in that the at least one ethylenically unsaturated compound is a polycyclic compound. The copolymer (a) is selected from:

(a1) a fluorine-containing copolymer comprising a repeating unit derived from at least one ethylenically unsaturated compound, wherein at least one ethylenically unsaturated compound is a polycyclic compound and at least one other ethylenically unsaturated compound comprises at least one fluorine atom covalently bonded to an ethylenically unsaturated carbon atom; and

(a2) a fluorine-containing copolymer comprising a repeating unit derived from at least one polycyclic ethylenically unsaturated compound containing at least one fluorine atom, perfluoroalkyl group, and perfluoroalkoxy group covalently attached to a carbon atom contained in a ring structure and separated from each ethylenically unsaturated carbon atom of the ethylenically unsaturated compound by at least one covalently bonded carbon atom.

(a1) The at least one ethylenically unsaturated compound disclosed in (a) may be selected from:

CH₂＝CHO₂CR¹⁵(K)

CH₂＝CHOCH₂R¹⁵(L) CH₂＝CHOR¹⁵(M)

and

wherein:

m and n are each 0, 1 or 2, p is an integer of at least 3;

a and b are independently 1 to 3, but when b is 2, a is not 1, and vice versa;

R¹to R¹⁴Identical or different, each represents a hydrogen atom, a halogen atom, a hydrocarbon radical having from 1 to 14 carbon atoms, generally from 1 to 10 carbon atoms, and optionally substituted by at least one O, N, S, P or halogen atom, for example a carboxyl group, such as a secondary or tertiary alkyl carboxylic acid group or a carboxylate group;

R¹⁵is a saturated alkyl group of about 4 to about 20 carbon atoms, optionally containing one or more ether oxygen atoms, provided that the ratio of carbon atoms to hydrogen atoms is greater than or equal to 0.58;

R¹⁶to R²¹Each independently being a hydrogen atom, C₁-C₁₂Alkyl radical (CH)₂)_qCO₂A，CO₂(CH₂)_qCO₂A or CO₂A, wherein q is 1 to 12, A is hydrogen or an acid protecting group, with the proviso that R¹⁸To R²¹At least one of them being CO₂A。

A key feature of the copolymers of the present invention (and photoresists comprising the copolymers) is the synergistic combination of polycyclic repeat units with identical or different fluorine-containing repeat units, and further with all repeat units in the copolymer that do not contain aromatic functionality. The presence of polycyclic repeat units in the copolymer is important for the copolymer to have high plasma etch resistance (e.g., reactive ion etching). Polycyclic repeating units also cause high glass transition temperatures, which is important to maintain dimensional stability of the photoresist film. The presence of fluorine-containing repeating units is important for the copolymer to have high optical transparency, i.e., low light absorption in the extreme ultraviolet and extreme ultraviolet regions. In order to impart high optical clarity to the polymer, it is also desirable that the repeat units of the copolymer be free of aromatic functional groups.

In certain embodiments of the present invention, the polyfluoro copolymers may contain repeating units derived from at least one polycyclic ethylenically unsaturated compound having at least one atom or group selected from fluorine atoms, perfluoroalkyl groups, and perfluoroalkoxy groups covalently bonded to one of the carbon atoms in the ring structure. Fluorine atoms, perfluoroalkyl groups and perfluoroalkoxy groups have a tendency to inhibit polymerization of cyclic ethylenically unsaturated compounds by metal-catalyzed addition polymerization or metathesis polymerization when directly attached to an ethylenically unsaturated carbon atom. Thus, in these cases, it is important that the at least one fluorine atom, perfluoroalkyl group, and perfluoroalkoxy group be separated from each ethylenically unsaturated carbon atom of the ethylenically unsaturated compound by at least one covalently attached carbon atom. In addition, attaching the atom and/or group directly to the ring reduces the presence of undesirable non-fluorinated aliphatic carbon atoms.

The copolymers of the present invention surprisingly have a balance of properties that are important to the photoresist's performance necessary for use in semiconductor manufacturing. First, these copolymers have unexpectedly low light absorption in the extreme ultraviolet and extreme ultraviolet regions, including 193nm and 157nm wavelengths. Copolymers having low light absorption are important for formulating high photo-sensitive rate photoresists in which UV light is primarily absorbed by the photoactive component without being lost due to absorption by the copolymer (the substrate of the photoresist). Second, photoresists comprising the fluoropolymers of the invention desirably exhibit very low plasma etch rates. The latter property is important to provide the high resolution fine photoresist required in semiconductor fabrication. Suitable values for these properties are particularly important for imaging at 157nm, while achieving these properties. In this case, ultra-thin photoresists are required for high resolution, but these thin photoresists must be highly etch resistant so that the photoresist remains on the imaged substrate and protects the underlying substrate areas during etching.

In a preferred embodiment of the present invention, the photoresist composition comprises a copolymer comprising repeat units derived from at least one polycyclic comonomer (i.e., a comonomer comprising at least two rings, such as norbornene). This is important for three reasons: 1) the polycyclic monomers have a relatively high carbon to hydrogen ratio (C: H), which results in binder polymers containing repeating units of these polycyclic monomers generally having good plasma etch resistance; 2) polymers having repeating units derived from polycyclic monomers may preferably be fully saturated upon polymerization, generally with good transparency characteristics; and 3) polymers prepared from polycyclic monomers generally have higher glass transition temperatures, which improves dimensional stability during processing. The ethylenically unsaturated groups may be contained in polycyclic moieties, for example in the case of norbornene, or as pendant groups to polycyclic moieties, for example in vinyl 1-adamantanecarboxylate. Polymers composed of repeating units derived from polycyclic comonomers have high C: H ratios and low Ohnishi numbers (O.N.), where

O.N.＝N/(Nc-No)

N is the number of atoms in the polymer repeat unit, Nc is the number of carbon atoms in the polymer repeat unit, and No is the number of oxygen atoms in the polymer repeat unit. Ohnishi et al found a law of thumb (J.electrochem. Soc., Solid-State Sci.Technol.,130143(1983)), i.e., the Reactive Ion Etch (RIE) rate of the polymer is a linear function of the ohnisi number (O.N.). For example, poly (norbornene) has the formula poly (C)₇H₁₀) O.n. 17/7 ═ 2.42. Polymers composed primarily of carbon and hydrogen and containing polycyclic moieties and less oxygen-containing functional groups should have lower O.N. valuesAccording to Ohnishi's Law of thumb, there should be a correspondingly low (in an approximately linear manner) RIE rate.

As is well known to those skilled in the polymer art, ethylenically unsaturated compounds are free radically polymerized to provide polymers having repeating units derived from the ethylenically unsaturated compound. Specifically, an ethylenically unsaturated compound having the following structure is subjected to radical polymerization:

a polymer having the following repeating units was obtained:

wherein P, Q, S and T may independently represent, but are not limited to: H. f, Cl, Br, alkyl groups having 1 to 14 carbon atoms, aryl groups having 6 to 14 carbon atoms, aralkyl groups or cycloalkyl groups having 3 to 14 carbon atoms.

If only one ethylenically unsaturated compound is polymerized, the polymer formed is a homopolymer. If two or more different ethylenically unsaturated compounds are polymerized, a copolymer is formed.

Some representative examples of ethylenically unsaturated compounds and their corresponding repeating units are given below:

in the subsequent sections, the photoresist composition of the present invention will be described in terms of its constituent parts.

The photoresist of the invention comprises a fluorine-containing copolymer containing a repeating unit derived from at least one ethylenically unsaturated compound, and is characterized in thatCharacterized in that at least one ethylenically unsaturated compound is polycyclic and at least one ethylenically unsaturated compound contains at least one fluorine atom covalently bonded to an ethylenically unsaturated carbon atom. Representative ethylenically unsaturated compounds suitable for the fluorochemical copolymers of the present invention include, but are not limited to: tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene, 1, 1-difluoroethylene, vinyl fluoride, perfluoro- (2, 2-dimethyl-1, 3-dioxole), perfluoro- (2-methylene-4-methyl-1, 3-dioxolane), CF₂＝CFO(CF₂)_tCF＝CF₂Wherein t is 1 or 2, and RfOCF ═ CF₂Wherein Rf is a saturated fluoroalkyl group of 1 to about 10 carbon atoms. The fluorocopolymer of the present invention may contain any integer of additional fluorocopolymers including, but not limited to, those listed above. Preferred comonomers are tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene and RfOCF ═ CF₂Wherein Rf is a saturated fluoroalkyl group of 1 to about 10 carbon atoms. More preferred comonomers are tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene and RfOCF ═ CF₂Wherein Rf is a saturated perfluoroalkyl group of 1 to about 10 carbon atoms. The most preferred comonomers are tetrafluoroethylene and chlorotrifluoroethylene.

Representative comonomers of structure H include, but are not limited to:

(norbornene) as a component of the above-mentioned polymer,

representative comonomers of structure I include, but are not limited to:

(bicyclo [2.2.2]The content of the octyl-2-ene is as follows,

representative comonomers of structure J include, but are not limited to:

representative comonomers of structure K include, but are not limited to:

representative comonomers of structure L include, but are not limited to:

representative comonomers of structure M include, but are not limited to:

all copolymers of the invention containing comonomers of structure K, L and M are characterized by containing a fluorinated olefin and a comonomer of formula CH₂＝CHO₂CR²²Of the formula CH or₂＝CHOCH₂R²²Or CH₂＝CHOR²²In which R is²²Is a hydrocarbon group of about 4-20 carbon atoms and has a relatively high C: H ratio of greater than 0.58, since a high C: H ratio corresponds to good plasma etch resistance. This is in combination with a fluorinated olefin and a compound of formula CH₂＝CHO₂CR²³Of the formula CH or₂＝CHOCH₂R²³Or CH₂＝CHOR²³In which R is a vinyl ether copolymer of (A) and (B), in which R is a vinyl ether copolymer of (A)²³Having a lower of less than 0.58The ratio of C to H. R²²And R²³Is selected from the group consisting of alkyl, aryl, aralkyl, and cycloalkyl.

Representative structural N comonomers include, but are not limited to:

wherein a ═ H, (CH)₃)₃C，(CH₃)₃Si。

In the preferred embodiment described above having at least one unsaturated compound of structure H to N as the second comonomer, there is a limitation on the second monomer if (and only if) the fluorocopolymer does not contain an additional comonomer having a functional group selected from carboxylic acid and protected acidic group. In this case, the fluorocopolymer has only two comonomers (two of the above comonomers, no additional non-enumerated comonomers). In this case, sufficient functionality must be present in the at least one unsaturated compound (i.e., the recited second comonomer) selected from the group consisting of carboxylic acid and protected acidic groups to enable development of the inventive photoresist comprised of the fluoropolymer in the imagewise exposure detailed below. In these embodiments using a fluorocopolymer containing only two comonomers, the mole percent of the two comonomers in the copolymer may be from 90%, 10% to 10%, 90% for the fluoromonomer (first monomer) and the second comonomer, respectively. In general, the mole percentages of the two comonomers may be 60%, 40% to 40%, 60% for the fluoromonomer (first monomer) and the second comonomer, respectively.

For some embodiments, in addition to the two comonomers listed, i.e., (i) at least one ethylenically unsaturated compound containing at least one fluorine atom covalently attached to an ethylenically unsaturated carbon atom; and (ii) at least one unsaturated compound selected from the structures H-N, the fluorocopolymer of the invention may further contain an additional comonomer in any integer without limitation in number. Representative additional comonomers may include, but are not limited to: acrylic acid, methacrylic acid, t-butyl acrylate, t-butyl methacrylate, t-amyl acrylate, t-amyl methacrylate, isobutyl acrylate, isobutyl methacrylate, ethylene, vinyl acetate, itaconic acid and vinyl alcohol. In those embodiments where the polyfluoro copolymer has two such comonomers and is comprised of three or more comonomers, the mole percent of the second comonomer (i.e., (ii) at least one unsaturated compound selected from the group consisting of structures H-N) is from about 20 to about 80 mole percent, preferably from about 30 to about 70 mole percent, more preferably from about 40 to about 70 mole percent, and most preferably from about 50 to about 70 mole percent. The sum of the mole percentages of all other comonomers making up the copolymer represents the remainder, and when added to the mole percentage of the second comonomer totals 100%. The sum of the mole percentages of all other monomers in the copolymer, except the second comonomer, is approximately from about 80 to 20 mole%. The sum of the mole percentages of all other comonomers is preferably from about 70 to 30 mole%. More preferably, the sum of the mole percentages of all other comonomers is from about 60 to about 30 mole percent, and most preferably, the sum of the mole percentages of all other comonomers is from about 50 to about 30 mole percent. When the fluoropolymer is a terpolymer, a suitable ratio of fluoromonomer (said first monomer) to additional comonomer is approximately 5: 95 to 95: 5. If additional comonomers are present in the fluorocopolymer and the monomers have a sufficient number of acid groups or protected acid group functionality necessary for development, this functionality may or may not be present in the second comonomer, without limitation.

One fluoropolymer in the photoresist composition of the present invention contains repeating units derived from a comonomer having at least one fluorine atom covalently bonded to an ethylenically unsaturated carbon atom, which can be prepared by free radical polymerization. These polymers can be prepared using free radical initiators, such as azo compounds or peroxides, using bulk, solution, suspension or emulsion polymerization methods known to those skilled in the art.

One of the fluorine-containing copolymers of the photoresist composition of the present invention contains only repeat units derived from a full ring comonomer and is completely free of repeat units derived from a comonomer containing one or more fluorine atoms attached to an ethylenically unsaturated carbon atom, and can also be prepared by free radical polymerization, but can also be prepared by other polymerization methods, including vinyl addition polymerization and Ring Opening Metathesis Polymerization (ROMP). The latter two polymerization processes are known to the person skilled in the art. Vinyl addition polymerizations using nickel and palladium catalysts are disclosed in the following references: 1) okoroanyanwu u.; shimokawa, t.; byers, j.d.; willson, c.g.j.mol.catal.a: chemical 1998, 133, 93; 2) PCT WO97/33198(9/12/97), b.f. goodrich; 3) reinmuth, a.; mathew, j.p.; melia, j.; risse, w.macromol.rapid commu.1996, 17, 173; and 4) Breunig, S.; risse, w.makromol.chem.1992, 193, 2915. Ring-opening metathesis polymerization is disclosed in the above references 1) and 2), using ruthenium and iridium catalysts; and the following documents: 5) schwab, p.; grubbs, r.h.; ziller, j.w.j.am.chem.soc.1996, 118, 100; and 6) Schwab, P.; france, m.b.; ziller, j.w.; grubbs, r.h.angelw.chem.int.ed.engl.1995, 34, 2039.

Some of the fluorine-containing biopolymers of the photoresist compositions of the present invention contain fluorine-containing monomers (e.g., TFE) and cyclic olefins (e.g., norbornene), which appear to be, but are not limited to, alternating or nearly alternating copolymerized biopolymers having the following structure:

in this case, the present invention includes these alternating or nearly alternating copolymers, but is in no way limited to alternating copolymer structures.

These polymers are disclosed in WO00/17712 published 3/20/2000.

The polymer (b) is a branched polymer containing protected acidic groups, the polymer containing one or more branched segments chemically bonded along a linear backbone segment. Such branched polymers may be formed during the free radical addition polymerization of at least one ethylenically unsaturated macromer component and at least one ethylenically unsaturated comonomer. The ethylenically unsaturated macromonomer component has a number average molecular weight (Mn) of between several hundred and 40,000, and the linear backbone formed by polymerization has a number average molecular weight (Mn) of about 2000-500,000. The weight ratio of linear backbone to branched segment is from about 50: 1 to about 1: 10, preferably from about 80: 20 to about 60: 40. Typically, the macromer component has a number average molecular weight of 500 to about 40,000, more typically about 1000 and 15,000. The number average molecular weight (Mn) of such ethylenically unsaturated macromonomer components generally corresponds to about 2 to 500, typically 30 to 200, monomer units used to form the macromonomer component.

In a typical embodiment, the branched polymer contains 25 to 100 weight percent of compatibilizing groups, i.e., functional groups that enhance compatibility with the photoacid generator, preferably about 50 to 100 weight percent, more preferably about 75 to 100 weight percent. Compatible groups suitable for ionic photoacid generators include, but are not limited to, non-hydrophilic polar groups and hydrophilic polar groups. Suitable non-hydrophilic polar groups include, but are not limited to: cyano (-CN) and nitro (-NO)₂). Suitable hydrophilic polar groups include, but are not limited to, protic groups, such as hydroxyl (OH), amino (NH)₂) Ammonium, amide, imide, urethane, urea or mercapto; or carboxylic acids (CO)₂H) Sulfonic acid, sulfinic acid, phosphoric acid or salts thereof. Preferably, these compatibilizing groups are present in the side chain.

Typically, the protected acid groups (described below) generate carboxylic acid groups after exposure to UV and other actinic radiation followed by a post-exposure bake (i.e., during deprotection). The branched polymer present in the photosensitive composition of the invention generally contains from about 3 to about 40 weight percent of monomer units containing protected acidic groups, preferably from about 5 to about 50 percent, and more preferably from about 5 to about 20 percent. The branches of such preferred branched polymers typically contain from 35 to 100% protected acidic groups. Such a branched polymer, when fully deprotected (all protected acid groups are converted to free acid groups), has an acid number of from about 20 to about 500, preferably from about 30 to about 330, more preferably from about 30 to about 130, and similarly the ethylenically unsaturated macromer component has an acid number of from about 20 to about 650, more preferably from about 90 to about 300, and most of the free acid groups are in the side chains.

Various photosensitive compositions of this aspect of the invention contain a branched polymer containing protected acidic groups, referred to as a comb polymer. Branched polymers have branched segments, called polymer arms, which have a limited molecular weight and a limited weight ratio with respect to the linear backbone. In a preferred embodiment, the majority of protected acidic groups are present in the side chain. The composition also contains a component, such as a photoacid generator, which renders the composition reactive to radiant energy, especially in the ultraviolet region of the electromagnetic spectrum, especially far ultraviolet and extreme far ultraviolet regions.

In a particular embodiment, the branched polymer contains one or more branched segments chemically bonded along a linear backbone, wherein the branched polymer has a number average molecular weight (Mn) of about 500 to 40,000. The branched polymer contains at least 0.5 wt% branches. The branches, also referred to as polymer arms, are generally randomly distributed along the linear backbone. A "polymer arm" or branch is a polymer or oligomer of at least two repeating monomer units, covalently linked to a linear backbone. These branches, or polymer arms, may be incorporated into the branched polymer as a macromer component during addition polymerization of the macromer with the comonomer. For the purposes of the present invention, a "macromer" is a polymer, copolymer or oligomer having a molecular weight of from several hundred to about 40000 containing ethylenically unsaturated polymerizable end groups. Preferably the macromonomer is a linear polymer or copolymer terminated with an alkenyl group. Generally, the branched polymer is a copolymer having one or more polymeric branches, preferably at least two branches, characterized in that the monomer component used in the polymerization has from about 0.5 to about 80% by weight, preferably from about 5 to about 50% by weight, of macromonomer. The comonomer component used with the macromer in this polymerization process will also typically contain a single ethylenic linkage that is copolymerizable with the ethylenically unsaturated macromer.

The ethylenically unsaturated macromer and the branched segment of the branched polymer formed and/or the backbone of the branched polymer may incorporate one or more protected acidic groups. For the purposes of the present invention, a "protected acid group" is a functional group which, when deprotected, forms a free acid function, which increases the solubility, swelling or dispersibility in an aqueous environment of the macromonomer and/or branched polymer to which it is bound. The protected acidic groups may be incorporated into the ethylenically unsaturated macromonomer and branches of the formed branched polymer and/or into the backbone of the branched polymer during or after its formation. While addition polymerization of macromers and at least one ethylenically unsaturated monomer is preferred for forming the branched polymer, all known methods of preparing branched polymers using addition or polycondensation reactions can be used in the present invention. In addition, the use of preformed backbone and branched or in situ polymerized segments may also be used in the present invention.

The branched segments attached to the linear backbone may be derived from ethylenically unsaturated macromers as generally described in U.S. Pat. Nos. 4,680,352 and 4,694,054. The macromonomers are prepared by free-radical polymerization using cobalt compounds, in particular cobalt (II) compounds, as chain transfer catalysts. The cobalt (II) compound may be a pentacyanocobaltate (II) compound or a vicinal iminohydroxyimino compound, a dihydroxyimino compound, a diazadipimidatedidecylidene, a diazadipimidatedialkylundecadienyl, a tetraazatetraalkylcyclotetradecatetraene, a tetraazatetraalkylcyclododecene, a bis (difluoroboryl) diphenyloximinoacetate, a bis (difluoroboryl) dimethyloximinoacetate, N, N' -bis (salicylidene) ethylenediamine, a dialkyldiaza-dioxodialkyldodecadiene, or a cobalt (II) chelate of a dialkyldiazaonedioxydialkyltridecadiene. Low molecular weight methacrylate macromers can also be prepared using a pentacyanocobaltate (II) chain transfer catalyst as described in U.S. Pat. No. 4,722,984.

An example of a macromer for use with this method is a methacrylate polymer with acrylate or other vinyl monomers, where the polymer or copolymer has an ethylenic end and a hydrophilic functional group. Preferred monomer components for preparing the macromers include: t-butyl methacrylate (tBMA), t-butyl acrylate (tBA), Methyl Methacrylate (MMA), Ethyl Methacrylate (EMA), Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate; methyl Acrylate (MA), Ethyl Acrylate (EA), Butyl Acrylate (BA), 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), Methacrylic Acid (MA), Acrylic Acid (AA); esters of acrylic and methacrylic acid, wherein the ester group contains 1 to 18 carbon atoms; nitriles and amides of acrylic and methacrylic acids (e.g., acrylonitrile); methacrylic acid and glycidyl acrylate; itaconic Acid (IA) and itaconic anhydride (ITA), half esters and imides; maleic acid and anhydrides, half esters and imides; aminoethyl methacrylate; tert-butylaminoethyl methacrylate; dimethylaminoethyl methacrylate; diethylaminoethyl methacrylate; aminoethyl acrylate; dimethylaminoethyl acrylate; diethylaminoethyl acrylate; (ii) acrylamide; n-tert-octylacrylamide; vinyl methyl ether, Styrene (STY), α -methylstyrene (AMS), vinyl acetate, vinyl chloride, and the like.

Itaconic anhydride (ITA, 2-methylenesuccinic anhydride, CAS No. 2170-03-8) is a particularly advantageous comonomer for use in branched polymers because it has 2 reactive functional groups in the anhydride form which become 3 upon ring opening to form a diacid. The ethylenically unsaturated moiety is a first functional group that provides this comonomer with the ability to be incorporated into the copolymer by, for example, free radical polymerization. The anhydride moiety is a second functional group that can react with a variety of other functional groups to form a covalently bonded product. Examples of functional groups with which the anhydride moiety can react are the hydroxyl groups in alcohols, resulting in the formation of ester linkages. Upon reaction of the anhydride moiety of the ITA with the hydroxyl group, an ester linkage and a free carboxylic acid moiety are formed, which is a third functional group. The carboxylic acid functional group functions to impart aqueous solution processibility to the photoresist of the present invention. If a PAG with hydroxyl groups is used, as shown in certain embodiments, it is possible to covalently link (tether) the PAG (or other photoactive component) to the branched polymer of the ITA-containing covalent monomer through such ester bonds (or other covalent bonds, e.g., amide bonds, etc.).

The branched polymers may be prepared by any conventional addition polymerization process. Such branched polymers, or comb polymers, may be prepared from one or more compatible ethylenically unsaturated macromonomer components and one or more compatible conventional ethylenically unsaturated comonomer components. Preferred addition polymerizable ethylenically unsaturated comonomer components are acrylates, methacrylates and styrene and mixtures thereof. Suitable addition polymerizable ethylenically unsaturated comonomer components include: tert-butyl methacrylate (tBMA), tert-butyl acrylate (tBA), Methyl Methacrylate (MMA), Ethyl Methacrylate (EMA), Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate; methyl Acrylate (MA), Ethyl Acrylate (EA), Butyl Acrylate (BA), 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), methacrylic acid (MAA), Acrylic Acid (AA); acrylonitrile (AN), Methacrylonitrile (MAN), Itaconic Acid (IA) and anhydride (ITA), half esters and imides, maleic acid and anhydride, half esters and imides, aminoethyl methacrylate, t-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, aminoethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, acrylamide, N-t-octylacrylamide, vinyl methyl ether, styrene, α -methylstyrene, vinyl acetate, vinyl chloride, and the like. The majority of the copolymerizable monomers must be acrylates or styrene, or copolymers of these monomers with acrylates and other vinyl monomers.

The linear backbone and/or branch components of the branched polymers of the present invention may each containThere are a wide variety of functional groups. "functional group" is considered to be any moiety capable of being attached to a backbone or branch by a direct bond or by a linking group. An example of a functional group which the main chain or the branch chain may have is-COOR²⁴、-OR²⁴、-SR²⁴Wherein R is²⁴May be hydrogen, alkyl of 1 to 12 carbon atoms, cycloalkyl of 3 to 12 carbon atoms, aryl, alkaryl or aralkyl of 6 to 14 carbon atoms, heterocyclyl containing 3 to 12 carbon atoms and additionally containing an S, O, N or P atom; OR-OR²⁷Wherein R is²⁷Can be an alkyl group of 1 to 12 carbon atoms, an aryl group of 6 to 14 carbon atoms, an alkaryl group or an aralkyl group; CN; -NR²⁵R²⁶Or

Wherein R is²⁵And R²⁶Can be hydrogen, alkyl of 1 to 12 carbon atoms; cycloalkyl of 3 to 12 carbon atoms; aryl, alkaryl, aralkyl groups of 6 to 14 carbon atoms; -CH₂OR²⁸Wherein R is²⁸Is hydrogen, alkyl of 1 to 12 carbon atoms; or is cycloalkyl of 3 to 12 carbon atoms, aryl, alkaryl, aralkyl of 6 to 14 carbon atoms, or R²⁵And R²⁶May combine to form a heterocyclic ring having from 3 to 12 carbon atoms and at least one of S, N, O or P;

wherein R is²⁹、R³⁰And R³¹Can be hydrogen, alkyl of 1 to 12 carbon atoms or cycloalkyl of 3 to 12 carbon atoms; aryl, alkaryl, aralkyl of 6 to 14 carbon atoms, or-COOR²⁴(ii) a Or R²⁹、R³⁰And/or R³¹May be taken together to form a cyclic group; -SO₃H; a carbamate group; an isocyanate or a protected isocyanate group; a urea group; an ethylene oxide group; 1-aziridinyl; a quinonediazido group; dollA nitrogen group; an azide group; a diazo group; acetyl acetoxy; -SiR³²R³³R³⁴Wherein R is³²、R³³And R³⁴Can be an alkyl group of 1 to 12 carbon atoms OR a cycloalkyl group of 3 to 12 carbon atoms OR-OR³³Wherein R is³⁵Is alkyl of 1 to 12 carbon atoms or cycloalkyl of 3 to 12 carbon atoms; aryl, alkaryl or aralkyl groups of 6 to 14 carbon atoms; or is-OSO₃R³⁶，-OPO₂R³⁶，-PO₂R³⁶，-PR³⁶R³⁷R³⁸，-OPOR³⁶，-SR³⁶R³⁷or-N⁺R³⁶R³⁷R³⁸Group (wherein R³⁶、R³⁷And R³⁸Can be hydrogen, alkyl of 1 to 12 carbon atoms or cycloalkyl of 3 to 12 carbon atoms; aryl, alkaryl or aralkyl groups of 6 to 14 carbon atoms; or a salt or onium salt of any of the above. Preferred functional groups are-COON, -OH, -NH₂Amide groups, vinyl groups, urethane groups, isocyanate groups, protected isocyanate groups, or combinations thereof. These functional groups may be located at any position of the branched polymer. However, it is sometimes desirable to select comonomers that impart properties to the linear backbone bulk polymer of the branched polymer, and to select macromers that impart physical and chemical functions of branching, such as solubility, reactivity, etc., in addition to hydrophilicity.

In certain preferred embodiments of the present invention, the branched polymer contains functional groups compatible with the photoacid generator, the functional groups being distributed in the branched polymer wherein 25 to 100% of the functional groups are located in the segment of the branched polymer containing the majority of protected acid groups. These functional groups are desirable because they increase the compatibility of the photoacid generator with branched polymers having segments containing a majority of protected acid groups, resulting in increased photoresist photospeed and perhaps resolution and/or other desired properties of photoresists comprising these branched polymers with compatibility-promoting functional groups. For ionic PAGs, such as triarylsulfonium salts, functional groups that promote compatibility include, but are not limited to, polar, non-hydrophilic groups (e.g., nitro or cyano) and polar, hydrophilic groups (e.g., hydroxyl, carboxyl). For nonionic PAGs, such as structure III above, the preferred compatibility-imparting functional groups are less polar than the polar groups listed above. For the latter case, suitable functional groups include, but are not limited to, those groups that can impart chemical and physical properties quite similar to the nonionic PAG. As two specific examples, aromatic functional groups and perfluoroalkyl functional groups are effective in improving the compatibility of the branched polymer with the nonionic PAG (e.g., structure III given above).

In some embodiments, the branched polymer is an acrylic acid/methacrylic acid/styrene copolymer comprising at least 60% by weight acrylate and at least 60% of the methacrylate repeat units are located at a first site or a second site, the first site being one of the segments (i.e., a branched or linear backbone) and the second site being a segment different from the first site, wherein at least 60% of the acrylate repeat units are at the second site.

In some embodiments, the branched polymer is a fluorine-containing graft copolymer comprising repeating units derived from at least one ethylenically unsaturated compound comprising at least one fluorine atom covalently bonded to an ethylenically unsaturated carbon atom. The repeating units bearing at least one fluorine atom may be in a linear polymer backbone or in a branched polymer segment; preferably the repeat unit is located in the polymer backbone. Representative ethylenically unsaturated compounds suitable for the fluorochemical graft copolymers of the present invention include, but are not limited to: tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene, 1, 1-difluoroethylene, vinyl fluoride and RfOCF ═ CF₂Wherein Rf is a saturated perfluoroalkyl group of 1 to about 10 carbon atoms. The fluorocopolymer of the present invention may contain any integer of additional fluorocopolymers including, but not limited to, those listed above. Preferred comonomers are tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene and RfOCF ═ CF₂Wherein Rf is a saturated perfluoroalkyl group of 1 to about 10 carbon atoms. More preferred copolymerizationThe monomers are tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene and RfOCF ═ CF₂Wherein Rf is a perfluoroalkyl group of 1 to about 10 carbon atoms. The most preferred comonomers are tetrafluoroethylene and chlorotrifluoroethylene.

In some embodiments, the fluorine-containing graft copolymer further contains a repeating unit derived from at least one unsaturated compound having the structure shown above for the polymer (a).

In one embodiment of the invention, the PAG is covalently bonded (i.e., tethered) to the fluorochemical graft copolymer to form a photoresist.

In some preferred embodiments, the branched polymer is a fluorine-containing copolymer comprising repeating units derived from at least one ethylenically unsaturated compound comprising a chlorohydrin-functional group having the structure:

-C(Rf)(Rf’)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂)_nWherein n is 2 to 10.

A branched fluorine-containing copolymer comprising repeating units derived from at least one ethylenically unsaturated compound containing a fluoroalcohol functional group of the invention, said copolymer may contain a fluoroalkyl group as part of the fluoroalcohol functional group. These fluoroalkyl groups may be represented by Rf and Rf', and they may be partially fluorinated alkyl groups or fully fluorinated alkyl groups (i.e., perfluoroalkyl groups). In general, Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together as (CF)₂)_nWherein n is 2 to 10 (in the above sentence, "taken together" means that Rf and Rf' are not separate individual fluoroalkyl groups, but together they form a ring structure as shown for example in the case of a 5-membered ring:

rf and Rf' are partially fluorinated alkyl groups according to the present invention and are not limited, but must have a sufficient degree of fluorination to render the hydroxyl (-OH) groups of the fluoroalcohol functional groups acidic so as to be substantially removed in an alkaline medium, such as aqueous sodium hydroxide or aqueous tetraalkylammonium hydroxide. In a preferred aspect of the invention, there is a sufficient degree of fluorine substitution in the fluorinated alkyl group of the fluoroalcohol functional group such that the pKa value of the hydroxyl group is as follows: pKa is more than 5 and less than 11. Preferably Rf and Rf 'are independently a perfluoroalkyl group of 1 to 5 carbon atoms, and most preferably both Rf and Rf' are trifluoromethyl (CF)₃). Each of the fluorocopolymers of the invention preferably has an absorption coefficient at 157nm of less than 4.0. mu.m^-1Preferably less than 3.5 μm^-1Preferably, the absorption coefficient at this wavelength is less than 3.0 μm^-1。

The fluorinated polymers, photoresists and methods of the invention include a fluoroalcohol functional group that may have the following structure:

-ZCH₂C(Rf)(Rf’)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂)_nWherein n is 2 to 10; z is selected from oxygen, sulfur, nitrogen, phosphorus, other group VA elements and other group VIA elements. The terms "other group VA elements" and "other group VIA elements" are to be understood as any element within these groups of the periodic table of the elements other than the element in question (i.e. oxygen, sulfur, nitrogen, phosphorus). Oxygen is the preferred Z group.

Some non-limiting examples of representative fluoroalcohol functional group-containing comonomers falling within the scope of the present invention are listed below:

CH₂＝CHOCH₂CH₂OCH₂C(CF₃)₂OH CH₂＝CHO(CH₂)₄OCH₂C(CF₃)₂OH

as is well known to those skilled in the polymer art, ethylenically unsaturated compounds are free radically polymerized to provide polymers having repeat units derived from the ethylenically unsaturated compound. Specifically, the ethylenically unsaturated compound having the following structure is described above with respect to the copolymer (a 1):

the fluoropolymer (c) having at least one fluoroalcohol group is selected from:

(c1) a fluoropolymer comprising repeating units derived from at least one ethylenically unsaturated compound containing a fluoroalcohol functional group having the structure:

-C(Rf)(Rf’)OH

wherein Rf and Rf' are as described above;

(c2) a fluorine-containing copolymer comprising repeating units derived from at least one ethylenically unsaturated compound, characterized in that at least one ethylenically unsaturated compound is cyclic or polycyclic, at least one ethylenically unsaturated compound comprises at least one fluorine atom covalently attached to an ethylenically unsaturated carbon atom, and at least one ethylenically unsaturated compound comprises a fluoroalcohol functional group having the structure:

-C(Rf)(Rf’)OH

wherein Rf and Rf' are as described above;

(c3) a fluorine-containing copolymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing at least 3 fluorine atoms covalently bonded to two ethylenically unsaturated carbon atoms; and

(2) a repeating unit derived from an ethylenically unsaturated compound containing a fluoroalcohol functional group having the structure:

-C(Rf)(Rf’)OH

wherein Rf and Rf' are as described above;

(c4) a fluoropolymer comprising repeating units derived from at least one ethylenically unsaturated compound comprising a fluoroalcohol functional group having the structure:

-ZCH₂C(Rf)(Rf’)OH

wherein Rf and Rf' are as described above and Z is an element selected from group VA and other group VIA elements of the periodic Table of the elements (CAS version). Typically Z is a sulfur, oxygen, nitrogen or phosphorus atom;

(c5) a fluoropolymer comprising the structure:

wherein each R⁴⁰、R⁴¹、R⁴²And R⁴³Independently a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 10 carbon atoms, a hydrocarbon group of 1 to 12 carbon atoms substituted with O, S, N, P or a halogen, for example, an alkoxy group, a carboxylic acid group, a carboxylate group or a functional group comprising the structure:

-C(Rf)(Rf’)OR⁴⁴

wherein Rf and Rf' are as described above; r⁴⁴Is a hydrogen atom or an acid or base labile protecting group; v is the number of repeating units in the polymer; w is 0 to 4; at least one repeating unit having a structure such that R⁴⁰、R⁴¹、R⁴²And R⁴³At least one of which contains the structure C(Rf)(Rf’)OR⁴⁴For example, R⁴⁰、R⁴¹And R⁴²Is a hydrogen atom, and R⁴³Is CH₂OCH₂C(CF₃)₂OCH₂CO₂C(CH₃)₃In which CH₂CO₂C(CH₃)₃Is an acid-or base-labile protecting group, or R⁴³Is OCH₂C(CF₃)₂OCH₂CO₂C(CH₃)₃In which OCH₂CO₂C(CH₃)₃Is an acid or base labile protecting group; and

(C6) a polymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing a fluoroalcohol functional group having the structure:

-C(Rf)(Rf’)OH

wherein Rf and Rf' are as described above; and

(2) a repeating unit derived from at least one ethylenically unsaturated compound of the structure:

(H)(R⁴⁵)C＝C(R⁴⁶)(CN)

wherein R is⁴⁵Is a hydrogen atom or a CN group; r⁴⁶Is C₁-C₈Alkyl, hydrogen atom or CO₂R⁴⁷Group, wherein R⁴⁷Is C₁-C₈Alkyl groups or hydrogen atoms.

These fluoropolymers or copolymers contain a repeating unit derived from at least one ethylenically unsaturated compound (discussed below) containing a fluoroalcohol functional group, which may contain a fluoroalkyl group as part of the fluoroalcohol group, and are described above for copolymer (b). These fluoroalkyl groups are represented by Rf and Rf' as described above.

As is well known to those skilled in the polymer art, ethylenically unsaturated compounds are free radically polymerized to provide polymers having repeat units derived from the ethylenically unsaturated compound. Specifically, the ethylenically unsaturated compound having the following structure is described above with respect to copolymer (a 1):

the absorption coefficient of each fluorine-containing copolymer of the present invention is less than 4.0 μm at a wavelength of 157nm^-1Preferably less than 3.5 μm^-1More preferably, the absorption at this wavelength is less than 3.0 μm^-1Preferably less than 2.5 μm^-1。

The fluorinated polymers, photoresists, and methods of the invention include a fluoroalcohol functional group that may have the following structure:

-ZCH₂C(Rf)(Rf’)OH

wherein Rf and Rf' are as defined above and Z is as defined above.

Some non-limiting examples of representative comonomers containing a fluoroalcohol functional group falling within the scope of the present invention are listed below:

CH₂＝CHOCH₂CH₂OCH₂C(CF₃)₂OH CH₂＝CHO(CH₂)₄OCH₂C(CF₃)₂OH

various difunctional compounds which first provide crosslinking and are subsequently cleaved off, for example on contact with strong acids, may also be used as comonomers in the copolymers of the invention. As a non-limiting example, a difunctional comonomer NB-F-OMOMO-F-NB is a desirable comonomer in the copolymers of the present invention. Such and similar difunctional comonomers, when present in the copolymer component of the photoresist composition of the invention, enable the copolymer to have a higher molecular weight and to be lightly crosslinked. Photoresist compositions incorporating these difunctional monomer-containing copolymers can have improved development and imaging characteristics because upon exposure (when a strong acid is photochemically generated, as explained below) cleavage of the difunctional groups results in a significant decrease in molecular weight, a factor that can greatly improve development and imaging characteristics (e.g., contrast improvement). These fluoroalcohol groups and their use are described in more detail in PCT/US00/11539, filed earlier and on 28.4.2000

Embodiments are described.

At least a portion of the nitrile functional groups present in the nitrile/fluoroalcohol polymer are the result of incorporation of repeat units derived from at least one ethylenically unsaturated compound having at least one nitrile group and the following structure:

(H)(R⁴⁸)C＝C(R⁴⁹)(CN)

wherein R is⁴⁸Is a hydrogen atom or a cyano group (CN); r⁴⁹Is an alkyl group of 1 to about 8 carbon atoms, CO₂R⁵⁰Wherein R is⁵⁰Is an alkyl group of 1 to about 8 carbon atoms, or is a hydrogen atom. Preferred are acrylonitrile, methacrylonitrile, fumaronitrile (trans-1, 2-dicyanoethylene) and maleonitrile (cis-1, 2-dicyanoethylene). Most preferred is acrylonitrile.

The nitrile/fluoroalcohol polymers are generally characterized as having repeating units derived from at least one ethylenically unsaturated compound containing fluoroalcohol groups in the range of about 10 to about 60 mole percent of the nitrile/fluoroalcohol polymer and repeating units derived from at least one ethylenically unsaturated compound containing at least one nitrile group in the range of about 20 to about 80 mole percent. Such nitrile/fluoroalcohol polymers are more commonly characterized as having repeat units derived from at least one fluoroalcohol functional ethylenically unsaturated compound in an amount less than or equal to 45 mole percent, and more typically less than or equal to 30 mole percent, of the polymer and having a minor amount of repeat units containing nitrile groups making up at least a portion of the remainder of the polymer, in view of achieving low absorption coefficient values.

In one embodiment, the polymer comprises at least one protected functional group. The functional group of the at least one protected functional group is typically selected from an acidic functional group and a basic functional group. Non-limiting examples of functional groups among the protected functional groups are carboxylic acids and fluoroalcohols.

In another embodiment, the nitrile/fluoroalcohol polymer may include aliphatic polycyclic functionality. In this embodiment, the percentage of repeating units containing aliphatic polycyclic functionality in the nitrile/fluoroalcohol polymer is from about 1 to about 70 mole percent, preferably from about 10 to about 55 mole percent, and more typically from about 20 to about 45 mole percent.

The nitrile/fluoroalcohol polymers may contain additional functional groups in addition to those specifically mentioned and noted herein, provided that aromatic functionality is preferably absent from the nitrile/fluoroalcohol polymers. It has been found that the presence of aromatic functionality in these polymers detracts from their light transmission properties, making them too absorbing in the deep UV and extreme far ultraviolet regions to be suitable for use in layers imaged at these wavelengths.

In some embodiments, the polymer is a branched polymer containing one or more branches chemically linked along a linear backbone. The branched polymer may be formed during the free radical addition polymerization of at least one ethylenically unsaturated macromonomer component with at least one ethylenically unsaturated comonomer. The branched polymers may be prepared by any conventional addition polymerization process. Such branched polymers, or comb polymers, may be prepared from one or more compatible ethylenically unsaturated macromonomer components and one or more compatible conventional ethylenically unsaturated monomer components. Typical addition polymerizable ethylenically unsaturated monomer components are acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, protected and/or unprotected unsaturated fluoroalcohols, and protected and/or unprotected unsaturated carboxylic acids. The structure and preparation of such branched polymers is discussed above and in WO00/25178 for type (b) polymers.

The fluoropolymer comprising at least one fluoroalcohol may also contain a spacer group selected from the group consisting of ethylene, alpha-olefins, 1, 1' -disubstituted olefins, vinyl alcohols, vinyl ethers, and 1, 3-dienes.

Polymer (d) comprises perfluoro (2, 2-dimethyl-1, 3-dioxole) or CX₂＝CY₂(wherein X ═ F or CF₃Amorphous vinyl homopolymer of (Y ═ H), or perfluoro (2, 2-dimethyl-1, 3-dioxole) and CX₂＝CY₂Optionally containing one or more comonomers CR⁵¹R⁵²＝CR⁵³R⁵⁴Wherein each R⁵¹、R⁵²、R⁵³Independently selected from H or F, wherein R⁵⁴Is selected from-F, -CF₃、-OR⁵⁵、R⁵⁵Is CnF_2n+1(n-1 to 3), -OH (when R is present)⁵³H) and Cl (when R is present)⁵¹、R⁵²And⁵³f). Polymer (d) may also comprise CH₂＝CHCF₃And CF₂＝CF₂In a ratio of 1: 2 to 2: 1, CH₂CHF and CF₂CFCl in a ratio of 1: 2 to 2: 1, CH₂CHF and CClH CF₂Amorphous vinyl copolymers of perfluoro (2-methylene-4-methyl-1, 3-dioxolane) and perfluoro (2, 2-dimethyl-1, 3-dioxolane) in any ratio, perfluoro (2-methylene-4-methyl-1, 3-dioxolane) and 1, 1-difluoroethylene in any ratio, and homopolymers of perfluoro (2-methylene-4-methyl-1, 3-dioxolane) in ratios of 1: 2 to 2: 1.

These polymers are prepared by polymerization of fluoropolymers known in the art. All ofThe polymers are prepared by reacting monomers, inert fluids (e.g., CF)₂ClCCl₂F，CF₃CFHCFHCF₂CF₃Or carbon dioxide) and a soluble free radical initiator (e.g., HFPO dimer peroxide)1Or Perkadox^16N) was sealed in a cooled autoclave and then heated to initiate the reaction if necessary.

CF₃CF₂CF₂OCF(CF₃)(C＝O)OO(C＝O)CF(CF₃)OCF₂CF₂CF₃

1

For HFPO dimer peroxides1Room temperature (. about.25 ℃ C.) is a convenient polymerization temperature, and for Perkadox^Temperatures of 60-90 ℃ may be used. Depending on the monomer and polymerization temperature, the pressure may vary from atmospheric to 500psi or higher. Then separating by filtration when the polymer is formed as an insoluble precipitate; if the polymer is dissolved in the reaction mixture, it is isolated by evaporation or precipitation. In many cases, the apparently dry polymer, which still retains a significant amount of solvent and/or unreacted monomers, must be further dried in a vacuum oven, preferably under a stream of nitrogen. Many of these polymers can also be prepared by aqueous emulsion polymerization by mixing deionized water, an initiator (e.g., ammonium persulfate or Vazo)^56WSP), monomers, surfactants (e.g. ammonium perfluorooctanoate) or dispersants (e.g. methyl cellulose) are sealed in a cooled autoclave and heated to initiate polymerization. The polymer may be isolated by breaking the formed emulsion, filtering and drying. Oxygen should be excluded from the reaction mixture in all cases. Chain transfer agents, such as chloroform, may be added to reduce the molecular weight.

The nitrile/fluoroalcohol-containing polymer (e) prepared from a substituted or unsubstituted vinyl ether comprises:

(e1) a polymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing a vinyl ether functional group of the structure:

CH₂＝CHO-R⁵⁶

wherein R is⁵⁶Is alkyl of 1 to 12 carbon atoms, aryl, aralkyl or alkaryl of 6 to about 20 carbon atoms, or substituted with S, O, N or a P atom; and

(2) a repeating unit derived from at least one ethylenically unsaturated compound of the structure

(H)(R⁵⁷)C＝C(R⁵⁸)(CN)

Wherein R is⁵⁷Is a hydrogen atom or a cyano group; r⁵⁸Is an alkyl group of 1 to about 8 carbon atoms, CO₂R⁵⁹Group, wherein R⁵⁹Is an alkyl group of 1 to about 8 carbon atoms or a hydrogen atom; and

(3) a repeating unit derived from at least one acidic group-containing ethylenically unsaturated compound; and

(e2) a polymer which comprises

(1) A repeating unit derived from at least one ethylenically unsaturated compound containing a vinyl ether functional group and a fluoroalcohol functional group of the following structure:

C(R⁶⁰)(R⁶¹)＝C(R⁶²)-O-D-C(Rf)(Rf’)OH

wherein R is⁶⁰、R⁶¹And R⁶²Independently an alkyl group of 1 to about 3 carbon atoms; d is at least one atom linking the vinyl ether functional group to a carbon atom of the fluoroalcohol functional group through an oxygen atom; rf and Rf' are as described above; and

(2) a repeating unit derived from at least one ethylenically unsaturated compound of the structure

(H)(R⁵⁷)C＝C(R⁵⁸)(CN)

Wherein R is⁵⁷Is a hydrogen atom or a cyano group; r⁵⁸Is an alkyl group of 1 to about 8 carbon atoms, CO₂R⁵⁹Group, wherein R⁵⁹Is an alkyl group of 1 to 8 carbon atoms or a hydrogen atom;

(3) a repeating unit derived from at least one ethylenically unsaturated compound containing an acidic group.

The fluoroalcohol groups and embodiments are described in more detail above for polymer (c 6). Some non-limiting illustrative examples of vinyl ether monomers having the general structural formulas given above for the fluoroalcohol functional groups falling within the scope of the present invention are listed below:

CH₂＝CHOCH₂CH₂OCH₂C(CF₃)₂OH CH₂＝CHO(CH₂)₄OCH₂C(CF₃)₂OH

the nitrile groups and embodiments thereof, as well as the resulting linear and branched polymers containing nitrile groups and fluoroalcohol groups and embodiments thereof, are also described and referred to above in detail with respect to polymer (c 6).

These polymers may comprise from about 10 to about 99.5% by weight of the total composition (solids).

Photoactive component (PAC)

If the polymer in the polymer blend is not photoactive, the composition of the present invention may contain a photoactive component (PAC) that is not chemically bonded to the fluoropolymer, i.e., the photoactive component is a separate component in the composition. The photoactive component is typically a compound that generates an acid or base upon exposure to actinic radiation. PAC is referred to as a Photo Acid Generator (PAG) if it generates an acid upon exposure to actinic radiation. If a base is generated upon actinic radiation, the PAC is referred to as a photobase generator (PBG).

Suitable photoacid generators for the present invention include, but are not limited to:

1) sulfonium salts (structure 1), 2) iodonium salts (structure II), and 3) hydroxamates, such as structure III.

In structures I-II, R₁-R₃Independently is a substituted or unsubstituted aryl group or is a substituted or unsubstituted C₁-C₂₀Alkylaryl (arylalkyl). Representative aryl groups include, but are not limited to, phenyl and naphthyl. Suitable substituents include, but are not limited to, hydroxy (-OH) and C₁-C₂₀Alkoxy (e.g. C)₁₀H₂₁O). Anion X in structures I-II^-May be but is not limited to SbF₆ ^-(hexafluoroantimonate), CF₃SO₃ ^-(triflate) and C₄F₉SO₃ ^-(perfluorobutanesulfonate).

Dissolution inhibitors

A wide variety of dissolution inhibitors may be used in the present invention. Preferably, the Dissolution Inhibitors (DI) for extreme ultraviolet and extreme ultraviolet photoresists, such as 193nm photoresists, are designed/selected to meet multiple material requirements, including dissolution inhibition, plasma etch resistance, and adhesion properties of the photoresist composition containing a given DI additive. Some dissolution inhibiting compounds also function as plasticizers in the photoresist composition.

Other Components

The compositions of the present invention may contain optional additional components. Examples of additional components that may be added include, but are not limited to: resolution enhancers, adhesion promoters, residue reducers, coating aids, plasticizers, and Tg (glass transition temperature) modifiers. A crosslinking agent may also be present in the negative photoresist composition. Some typical crosslinkers include bis-azides such as 4, 4 '-diazidodiphenyl sulfide and 3, 3' -diazidodiphenyl sulfone. Typically, negative-working photoresist compositions containing at least one crosslinker also contain suitable functionality (e.g., unsaturated C ═ C bonds) that can react with reactive species (e.g., nitrenes) generated upon exposure to UV light, so as to produce crosslinked polymers that do not dissolve, disperse, or significantly swell in the developer solution.

Method of forming photoresist image

A method of preparing a photoresist image on a substrate comprising, in order:

(X) imagewise exposing the photoresist layer to form imaged areas and non-imaged areas, wherein the photoresist layer is prepared from a photoresist composition comprising:

(A) at least two polymers selected from (a) to (e); and

(B) a photoactive compound; and

(Y) developing the exposed photoresist layer with imaged areas and non-imaged areas to form a relief image on the substrate.

Imagewise exposure

The photoresist layer is prepared by applying a photoresist composition to a substrate and drying to remove the solvent. The photoresist layer formed in this way is sensitive to the ultraviolet region of the electromagnetic spectrum, in particular to the region with the wavelength less than or equal to 365 nm. Imagewise exposure of the photoresist compositions of the invention can be carried out at many different UV wavelengths, including but not limited to 365nm, 248nm, 193nm, 157nm and lower. The imagewise exposure is preferably carried out with ultraviolet light of 248nm, 193nm, 157nm or less, more preferably 193nm, 157nm or less, most preferably 157nm or less. The imagewise exposure can be carried out digitally with a laser or comparable apparatus or non-digitally with a photomask. Preferably, the digital imaging is performed with a laser. Laser devices suitable for digital imaging of the compositions of the invention includeBut are not limited to: Ar-F excimer laser with 193nm UV output, Kr-F excimer laser with 248nm UV output and F with 157nm output₂A laser. As discussed previously, because imagewise exposure using lower wavelength UV light corresponds to higher resolution (lower resolution limit), the use of shorter wavelengths (e.g., 193nm or 157nm or less) is generally preferred over the use of longer wavelengths (e.g., 248nm or more).

Development

The components of the photoresist composition of the present invention must contain sufficient functionality for development after imaging exposure to UV light. Preferably, the functionality is an acid or a protected acid to enable aqueous development with an alkaline developer, such as sodium hydroxide solution, potassium hydroxide solution, or ammonium hydroxide solution.

For example, polymer (C) in the photoresist composition of the present invention is typically an acid-containing species comprising at least one fluoromonomer structural unit:

-C(Rf)(Rf’)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to 10 carbon atoms, or taken together are (CF)₂)_RWherein n is 2 to 10. The content of acidic fluoroalcohol groups for a given composition is determined by optimizing the amount required to achieve good development in an alkaline aqueous developer.

When an aqueous processable photoresist is coated or applied to a substrate and exposed image-wise to UV light, development of the photoresist composition may require that the binder material contain sufficient acidic groups (e.g., fluoroalcohol groups) and/or protected acidic groups that are at least partially deprotected upon exposure so that the photoresist (or other photoimageable coating composition) can be processed in an aqueous alkaline developer. In the case of a positive photoresist layer, the portions of the photoresist layer exposed to ultraviolet radiation during development will be removed, but the unexposed portions will be substantially unaffected by development with an aqueous alkaline solution (e.g., an aqueous all-water solution containing 0.262N tetramethylammonium hydroxide) at 25 deg.C (typically less than or equal to 120 seconds). In the case of a negative photoresist layer, the portions of the photoresist layer not exposed to UV radiation will be removed upon development, but the exposed portions will be substantially unaffected during development with critical fluids or organic solvents.

As used herein, a critical fluid is one or more substances that are heated to near or above their critical temperature and compressed to near or above their critical pressure. The critical fluid of the present invention is at least at a temperature 15 c above the critical temperature of the fluid and at least at a pressure 5 atm above the critical pressure of the fluid. Carbon dioxide may be used as the critical fluid in the present invention. Various organic solvents can also be used as the developer of the present invention. This includes, but is not limited to, halogenated solvents and non-halogenated solvents. Halogenated solvents are commonly used, and fluorinated solvents are more commonly used.

Substrate

The substrate used in the present invention may be, for example, silicon dioxide, silicon nitride, or various other materials used in semiconductor fabrication.

Examples

Term(s) for

Analysis/assay

bs wide singlet

NMR chemical shifts of delta measured in the indicated solvents

g

NMR nuclear magnetic resonance

¹HNMR proton NMR

¹³C NMR carbon-13 NMR

¹⁹F NMR fluorine-19 NMR

s single peak

sec

m multiplet

mL of

mm

Tg glass transition temperature

Number average molecular weight of Mn given Polymer

Mw given the weight average molecular weight of the polymer

Polydispersity of a given polymer

Absorption coefficient AC ═ A/b, where A (absorbance) ═ log₁₀(l/T), b is film thickness

Degree (μm), T ═ light transmittance defined below

Transmittance T-radiation power measured at a specific wavelength (nm) through a sample

Ratio of radiant power irradiated to the sample

Chemicals/monomers

AA olefine acid

Aldrich Chemical Co.，Milwaukee，WI

AIBN 2, 2' -azobisisobutyronitrile

Aldrich Chemical Co.，Milwaukee，WI

CFC-1131, 1, 2-trichlorotrifluoroethane

(E.I.du Pont de Nemours and Company，

Wilmington，DE)

HFIBO hexafluoroisobutylene epoxide

MEK 2-butanone

Aldrich Chemical Co.，Milwaukee，WI

NB norbornene ═ bicyclo [2.2.1] hept-2-ene

Aldrich Chemical Co.，Milwaukee，WI

Perkadox^16N bis (4-tert-butylcyclohexyl) peroxydicarbonate

Noury Chemical Corp.，Burt，NY

PGMEA propylene glycol methyl Ether acetate

Aldrich Chemical Co.，Milwaukee，WI

tBA Tert-butyl acrylate

TBLC Choline tert-butyl ester

TCB trichlorobenzene

Aldrich Chemical Co.，Milwaukee，WI

TFE tetrafluoroethylene

(E.I.du Pont de Nemours and Company，

Wilmington，DE)

THF tetrahydrofuran

Aldrich Chemical Co.，Milwaukee，WI

Vazo^522, 4-dimethyl-2, 2' -azobis (valeronitrile)

(E.I.du Pont de Nemours and Company，

Wilmington，DE)

NB-F-O-t-BuAc

NB-F-O-t-BuAc

NB-Me-OH X＝OH

NB-Me-F-OH X＝OCH₂C(CF₃)₂OH

NB-Me-F-OMOM X＝OCH₂C(CF₃)₂OCH₂OCH₃

NB-OAc X＝OCOCH₃

NB-OH X＝OH

NB-F-OH X＝OCH₂C(CF₃)₂OH

NB-F-OMOM X＝OCH₂C(CF₃)₂OCH₂OCH₃

VE-F-OH CH₂＝CHOCH₂CH₂OCH₂C(CF₃)₂OH

VE-F-OMOM CH₂＝CHOCH₂CH₂OCH₂C(CF₃)₂OCH₂OCH₃

Ultraviolet light

Electromagnetic spectrum region from 10nm to 200nm in Extreme Ultraviolet (EUV)

Electromagnetic spectrum region from 200nm to 300nm in extreme ultraviolet

Ultraviolet region of electromagnetic spectrum with ultraviolet from 10nm to 390nm

Electromagnetic spectrum region from 300nm to 390nm in near ultraviolet

Example 1: synthesis of TFE/NB-F-OH/tBA terpolymer NB-F-OH was synthesized as follows:

a dry round bottom flask equipped with a mechanical stirrer, addition funnel and nitrogen inlet was purged with nitrogen and charged with 19.7g (0.78mol) of 95% sodium hydride and 500mL of anhydrous DMF. The mixture was cooled to 5 ℃ with stirring and 80.1g (0.728mol) of exo-5-norbornen-2-ol were added dropwise, the temperature being kept below 15 ℃. The resulting mixture was stirred for 0.5 h and HFIBO (131g, 0.728mol) was added dropwise at room temperature. The resulting mixture was stirred at room temperature overnight. Methanol (40ml) was added and most of the DMF was removed under reduced pressure on a rotary evaporator. The residue was treated with 200mL of water and glacial acetic acid was added until the pH was about 8.0. The aqueous mixture was extracted with 3X 150mL of diethyl ether. The combined ether extracts were washed with 3X 150mL of water and 150mL of brine, dried over anhydrous sodium sulfate, and concentrated to an oil on a rotary evaporator. Distillation in a Kugelrohr distiller at 0.15-0.20 torr and pot temperature 30-60 ℃ gave 190.1g (90%) of product.

¹H NMR(δCD₂Cl₂)1.10-1.30(m, 1H), 1.50(d, 1H), 1.55-1.65(m, 1H), 1.70(s, 1H), 1.75(d, 1H), 2.70(s, 1H), 2.85(s, 1H), 3.90(d, 1H), 5.95(s, 1H), 6.25(s, 1H). Another sample prepared in the same manner was submitted for elemental analysis. C₁₁H₁₂F₆O₂The calculated value of (a): c, 45.53; h, 4.17; f, 39.28. Experimental values: c, 44.98; h, 4.22; f, 38.25. The synthesis of NB-F-OH is described in PCT International application WO2000067072 (published 11/9/2000).

A200 mL stainless steel autoclave was charged with 48.7g (0.168mol) of NB-F-OH prepared as described above, 1.54g (0.012mol) of tert-butyl acrylate (tBA, Aldrich chemical company), 75mL of 1, 1, 2-trichlorotrifluoroethane and 0.6g of Perkadox^16. The vessel was sealed, cooled, evacuated and purged with nitrogen several times. Then 42g (0.42mol) of Tetrafluoroethylene (TFE) were charged. The autoclave contents were stirred at 50 ℃ for about 18 hours, resulting in a pressure change from 294psi to 271 psi. The vessel was cooled to room temperature and evacuated to 1 atmosphere. The vessel contents were removed by washing with 1, 1, 2-trichlorotrifluoroethane to give a clear solution. The solution was slowly added to an excess of hexane to form a white polymer precipitate, which was dried in a vacuum oven overnight. The yield was 11.3g (12%). GPC analysis: mn is 7300; mw 10300; Mw/Mn is 1.41. DSC analysis: a Tg of 135 ℃ was observed on the second heating. The fluorine NMR spectrum showed a fluorine content of-75.6 ppm (CF)₃) And-95 to-125 ppm (CF)₂) The peaks at (B) confirmed that NB-F-OH and TFE had been respectively substitutedAnd (4) combining. The polymer was analyzed by carbon NMR and, by integration of the appropriate peaks, was found to contain 39 mol% TFE, 42 mol% NB-F-OH and 18 mol% tBA.

And (3) analysis results: c, 43.75; h, 3.92; f, 40.45.

Example 2: preparation of a terpolymer of TFE, NB-F-OH and Tert-butyl acrylate

A metal pressure vessel having a capacity of about 270mL was charged with 71.05g of NB-F-OH, 0.64g of t-butyl acrylate and 25mL of 1, 1, 2-trichlorotrifluoroethane. The vessel was closed, cooled to about-15 ℃ and pressurized to 400psi with nitrogen and evacuated several times. The reactor was heated to 50 ℃ and TFE was added until the internal pressure reached 340 psi. 75.5g of NB-F-OH and 9.39g of tert-butyl acrylate diluted to 100mL with 1, 1, 2-trichlorotrifluoroethane were pumped in at a rate of 0.10 mL/min for a total of 12 hours. While the monomer raw material solution was initially charged, 6.3g of Perkadox was pumped into the reactor at a rate of 2.0 mL/min^16N and 30-35mL ethyl acetate were diluted with 1, 1, 2-trichlorotrifluoroethane to a 75mL solution for 6 minutes and then pumped in at a rate of 0.08 mL/min for 8 hours. TFE was added as needed to maintain the internal pressure at 340 psi. After 16 hours of reaction, the vessel was cooled to room temperature and evacuated to 1 atmosphere. The recovered polymer solution was slowly added to the excess hexane with stirring. The precipitate was filtered, washed with hexane and dried in a vacuum oven. The solid formed was dissolved in a mixture of THF and 1, 1, 2-trichlorotrifluoroethane and slowly added to an excess of hexane. The precipitate was filtered, washed with hexane and dried in a vacuum oven overnight to give 47.5g of a white polymer. According to which¹³C NMR spectrum of the polymer composition 35% TFE, 42% NB-F-OH and 22% tBA. DSC: tg 151 ℃. GPC: mn 6200; mw 9300; Mw/Mn is 1.50. And (3) analysis results: c, 44.71; h, 4.01; f, 39.38.

Example 3: the NB-Me-F-OH terpolymer was prepared by the following procedure:

0.19g (0.49mmol) of an allylpalladium complex (. eta.) was added under nitrogen³-MeCHCHCH₂)PdCl]₂And 0.34g (0.98mmol) of silver hexafluoroantimonate suspended in chlorobenzene (40 ml). The resulting mixture was stirred at room temperature for 30 minutes. The precipitated AgCl was then filtered off and a further 10mL of chlorobenzene were added. The resulting solution was added to 15.0g (49.0mmol) of NB-Me-F-OH. The reaction mixture was stirred at room temperature for 3 days. The crude polymer was isolated by precipitation in hexane. This was dissolved in acetone to give a 10% by weight solution, which was passed through a 0.2 μm Teflon^Filter membrane filtration and subsequent concentration of the acetone filtrate to dryness gave 7.8g of addition copolymer. GPC: mn 6387; mw 9104; Mw/Mn is 1.43. And (3) analysis results: c, 46.28; h, 4.81; f, 34.22. Of the polymer¹HNMR(CD₂Cl₂) Consistent with the saturated vinyl addition polymers listed below:

example 4: NB-F-OH/NB-F-O-t-BuAc copolymers were synthesized by polymer modification using the following procedure:

a500 mL round bottom flask equipped with a mechanical stirrer, addition funnel and reflux condenser was charged with 53.6g of NB-F-OH vinyl addition homopolymer (calculated to contain 0.185mol hexafluoroisopropanolate), 200mL of acetonitrile and 30.6g (0.222mol) of potassium carbonate. The mixture was refluxed for half an hour. Tert-butyl bromoacetate (10.8g, 0.055mol) was added dropwise and the resulting mixture was refluxed for 3 hours. After the mixture was cooled to room temperature, it was diluted with 300mL of acetone. The mixture was then filtered and concentrated under reduced pressure to a volume of about 200 ml. The concentrated mixture was poured slowly into 5.4L of 1.0% hydrochloric acid. The precipitate formed is filtered off and washed with water. The precipitate was then dissolved in 200ml of acetone, to which was added 5ml of water and 3ml of 36% hydrochloric acid to form a slightly mixed solution. The precipitate was poured into 5.4L of water, washed several times with water and dried to give 44.0g of NB-F-OH/NB-F-O-tBuAc copolymer.¹⁹FNMR (delta, acetone-d 6) -73.1(S, assigned to the unit from NB-F-O-t-BuAc), -75.4(S, assigned to the unit from NB-F-OH). Integrating the spectrogram to obtain a polymer groupTo 64% NB-F-OH and 36% NB-F-O-t-BuAc. The polymer samples were spin coated with a 5% solution of 2-heptanone. The absorption coefficient at 157nm was determined to be 3.15 μm at a film thickness of 47.2nm^-1And 2.70 μm at a film thickness of 45.7nm^-1。

Example 5:NB-Me-F-OH/NB-Me-F-O-tbuaac copolymers were synthesized by polymer modification using the following procedure:

example 4 was repeated with the following differences: NB-Me-F-OH/NB-Me-F-O-t-BuAc copolymer was synthesized using NB-Me-F-OH vinyl addition homopolymer instead of NB-F-OH alkenyl addition homopolymer.¹⁹FNMR (δ, acetone-d 6) -73.2(S, units designated NB-Me-F-O-tBuAc), -75.3(S, units designated NB-Me-F-OH). By spectrum integration, the polymer composition was 68% NB-Me-F-OH and 32% NB-Me-F-O-tBuAc.

Example 6:

the following formulation containing a 3: 1 polymer blend was formulated and stirred magnetically:

components Weight (gram)

TFE/NB-F-OH/t-BA copolymers (from¹³CNMR analysis 0.390

35/42/22) was prepared in a similar manner to that described in example 2

NB-Me-F-OH/NB-Me-F-O-Ac-tBu copolymer (b:)¹⁹FNMR analysis 0.130

68/32) similar to that described in example 5

2-heptanone 5.121

Lithocholic acid tert-butyl ester 0.060

6.82% (wt) solution of triphenylsulfonium nonafluorobutanesulfonate in 2-heptanone, 0.299

Filtering with 0.45 mu PTFE injection filter membrane

A4 inch diameter "P" type <100> oriented silicon wafer was spin coated using a Brewer Science Inc.100CB combination spin/hot plate machine. Developed on a Litho Tech japan co. photoresist developer (model 790).

5ml of Hexamethyldisilazane (HMDS) primer was placed on the silicon wafer and rotated at 5000rpm for 10 seconds. Then, 3ml of the above solution filtered through a 0.45 μm PTFE injection filter was placed, spun at 2500rpm for 60 seconds, and baked at 120 ℃ for 60 seconds.

To accomplish 248nm imaging, the coated wafer was exposed to broad spectrum UV light from a Solar Simulator (1000 Watts) type ORIEL82421 through a 248nm interference filter that transmits approximately 30% of the energy at 248 nm. The exposure time was 5 seconds, providing 7.5mJ/cm²The unattenuated dose of (a). A mask with 18 sites of different neutral optical density was used to produce a wide range of exposure doses. After exposure, the exposed silicon wafer was baked at 100 ℃ for 60 seconds. The silicon wafer was developed in aqueous tetramethylammonium hydroxide (TMAH) solution (ShipleyLDD-26W developer, 0.26N TMAH solution) to give a positive image.

Example 7

The following formulations containing a 1: 1 polymer blend were formulated and magnetically stirred:

components Weight (gram)

TFE/NB-F-OH/t-BA copolymer (¹³CNMR analysis 35/42/22), 0.260

Prepared in a similar manner to that described in example 2

NB-Me-F-OH/NB-Me-F-O-Ac-tBu copolymer (68/32,¹⁹FNMR 0.260

analysis) similar to that described in example 5

2-heptanone 5.121

Lithocholic acid tert-butyl ester 0.060

6.82% (wt) solution of triphenylsulfonium nonafluorobutanesulfonate in 2-heptanone, 0.299

Filtering with 0.45 mu PTFE injection filter membrane

The process was carried out as in example 6, but the exposure was carried out for 10 seconds, giving an unattenuated dose of 15mJ/cm². A positive image was obtained.

Example 8:

the following formulations containing a 1: 3 polymer blend were formulated and magnetically stirred:

components Weight (gram)

TFE/NB-F-OH/tBA copolymers (35/42/22,¹³CNMR analysis), 0.130

Prepared in a similar manner to that described in example 2

NB-Me-F-OH/NB-Me-F-O-AC-tBu copolymer (68/32,¹⁹FNMR 0.390

analysis) similar to that described in example 5

2-heptanone 5.121

Lithocholic acid tert-butyl ester 0.060

6.82% (wt) solution of triphenylsulfonium nonafluorobutanesulfonate in 2-heptanone, 0.299

Filtering with 0.45 mu PTFE injection filter membrane

The procedure is as in example 6, except that the exposure time is 10 seconds and the unattenuated dose is 15mJ/cm². A positive image was obtained.

Claims (17)

1. A photoresist composition comprising:

(A) at least two polymers selected from:

(a) a fluoropolymer comprising repeating units derived from at least one ethylenically unsaturated compound, wherein the at least one ethylenically unsaturated compound is a polycyclic compound;

(b) a branched polymer comprising protected acidic groups, the polymer comprising one or more branches chemically linked along a linear backbone;

(c) a fluoropolymer comprising at least one fluoroalcohol group of the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to about 10;

(d) perfluoro (2, 2-dimethyl-1, 3-dioxole) or CX₂＝CY₂Wherein X ═ F or CF₃Or is (2, 2-dimethyl-1, 3-dioxole) and CX₂＝CY₂The amorphous vinyl copolymer of (a); and

(e) nitrile/fluoroalcohol-containing polymers prepared from substituted or unsubstituted vinyl ethers; and

(B) at least one photoactive component.

2. The photoresist composition of claim 1 wherein the absorption coefficient of the polymer at a wavelength of about 157nm is less than about 5.0 μm^-1。

3. The photoresist composition of claim 1 wherein the absorption coefficient of the polymer at a wavelength of about 157nm is less than about 4.0 μm^-1。

4. The photoresist composition of claim 1 wherein the absorption coefficient of the polymer at a wavelength of about 157nm is less than about 3.5 μm^-1。

5. The photoresist composition of claim 1, where the polymer (a) is a fluorine-containing copolymer comprising repeating units derived from at least one ethylenically unsaturated compound, characterized in that at least one ethylenically unsaturated compound is a polycyclic compound and at least one ethylenically unsaturated compound contains at least one fluorine atom covalently attached to an ethylenically unsaturated carbon atom.

6. The photoresist composition of claim 1, where polymer (a) is a fluorine-containing copolymer containing repeating units derived from at least one ethylenically unsaturated polycyclic compound having at least one atom or group selected from the group consisting of fluorine atoms, perfluoroalkyl groups, and perfluoroalkoxy groups, characterized in that the at least one atom or group is covalently attached to a carbon atom contained within a ring structure and is separated from each ethylenically unsaturated carbon atom of the ethylenically unsaturated compound by at least one covalently attached carbon atom.

7. The photoresist composition of claim 1, where polymer (b) is a branched polymer containing protected acidic groups, the polymer containing one or more branches chemically linked along a linear backbone.

8. The photoresist composition of claim 1, wherein polymer (c) is selected from the group consisting of:

(C1) a fluoropolymer comprising repeating units derived from at least one ethylenically unsaturated compound containing a fluoroalcohol functional group having the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to about 10;

(C2) a fluorine-containing copolymer comprising repeating units derived from at least one ethylenically unsaturated compound, wherein at least one ethylenically unsaturated compound is a cyclic or polycyclic compound, at least one ethylenically unsaturated compound comprises at least one fluorine atom covalently attached to an ethylenically unsaturated carbon atom, and at least one ethylenically unsaturated compound comprises a fluoroalcohol functional group having the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to 10;

(C3) a fluorine-containing copolymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing at least 3 fluorine atoms covalently bonded to 2 ethylenically unsaturated carbon atoms; and

(2) a repeating unit derived from an ethylenically unsaturated compound containing a fluoroalcohol functional group having the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to 10;

(C4) a fluorine-containing copolymer comprising a repeating unit derived from at least one ethylenically unsaturated compound comprising a fluoroalcohol functional group having the structure:

-ZCH₂C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to 10; z is an element of group VA or group VIA of the periodic Table of the elements;

(C5) a fluoropolymer comprising the structure:

wherein each R⁴⁰、R⁴¹、R⁴²And R⁴³Independently a hydrogen atom, a halogen atom, a hydrocarbyl group containing 1 to 10 carbon atoms, a substituted hydrocarbyl group, an alkoxy group, a carboxylic acid ester, or a functional group containing the structure:

-C(Rf)(Rf′)OR⁴⁴

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to 10; r⁴⁴Is a hydrogen atom or an acid or base labile protecting group; v is the number of repeating units in the polymer; w is 0 to 4; at least one of the repeating units has a structure such that R⁴⁰、R⁴¹、R⁴²And R⁴³At least one of which comprises the structure C (Rf) (Rf') OR⁴⁴(ii) a And

(C6) a polymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing a fluoroalcohol functional group having the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to about 10; and

(2) a repeating unit derived from at least one ethylenically unsaturated compound of the structure:

(H)(R⁴⁵)C＝C(R⁴⁶)(CN)

wherein R is⁴⁵Is a hydrogen atom or a CN group; r⁴⁶Is C₁-C₈Alkyl radicals, hydrogen atoms, or CO₂R⁴⁷Group, wherein R⁴⁷Is C₁-C₈Alkyl groups or hydrogen atoms.

9. The photoresist composition of claim 8, where polymer (C) further comprises a spacer group selected from the group consisting of ethylene, alpha-olefins, 1, 1' -disubstituted olefins, vinyl alcohols, vinyl ethers, and 1, 3-dienes.

10. The photoresist composition of claim 1, where polymer (d) further comprises one or more monomers CR⁵¹R⁵²＝CR⁵³R⁵⁴Wherein each R⁵¹、R⁵²、R⁵³Independently selected from H or F, R⁵⁴Is selected from-F, -CF₃、-OR⁵⁵(wherein R is⁵⁵Is CnF_2n+1N is 1 to 3), -OH (when R is⁵³Is H) and Cl (when R is⁵¹、R⁵²And R⁵³When F).

11. The photoresist composition of claim 1 wherein polymer (d) further comprises an amorphous vinyl copolymer selected from the group consisting of：CH₂＝CHCF₃And CF₂＝CF₂In a ratio of 1: 2 to 2: 1, CH₂CHF and CF₂CFCL in a ratio of 1: 2 to 2: 1, CH₂CHF and CCLH CF₂Amorphous vinyl copolymers of perfluoro (2-methylene-4-methyl-1, 3-dioxolane) and perfluoro (2, 2-dimethyl-1, 3-dioxole) in any ratio in the ratio of 1: 2 to 2: 1; amorphous copolymers of perfluoro (2-methylene-4-methyl-1, 3-dioxolane) with 1, 1-difluoroethylene in any proportion; and homopolymers of perfluoro (2-methylene-4-methyl-1, 3-dioxolane).

12. The photoresist composition of claim 1, wherein polymer (e) is selected from the group consisting of:

(e1) a polymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing a vinyl ether functional group and having the structure:

CH₂＝CHO-R⁵⁶

wherein R is⁵⁶Is a substituted or unsubstituted alkyl, aryl, aralkyl, or alkaryl group of from 1 to about 20 carbon atoms; and

(2) a repeating unit derived from at least one ethylenically unsaturated compound of the structure:

(H)(R⁵⁷)C＝C(R⁵⁸)(CN)

wherein R is⁵⁷Is a hydrogen atom or a cyano group; r⁵⁸Is an alkyl group of 1 to about 8 carbon atoms, CO₂R⁵⁹Group (wherein R⁵⁹Alkyl of 1 to about 8 carbon atoms) or a hydrogen atom; and

(3) a repeating unit derived from at least one acidic group-containing ethylenically unsaturated compound; and

(e2) a polymer comprising:

(1) a repeating unit derived from at least one ethylenically unsaturated compound containing a vinyl ether functional group and a fluoroalcohol functional group and having the structure:

C(R⁶⁰)(R⁶¹)＝C(R⁶²)-O-D-C(Rf)(Rf′)OH

wherein R is⁶⁰、R⁶¹And R⁶²Each independently a hydrogen atom, an alkyl group of 1 to about 3 carbon atoms; d is at least one atom linking the vinyl ether functional group to a carbon atom of the chlorohydrin functional group through an oxygen atom; rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is an integer from 2 to about 10; and

(2) a repeating unit derived from at least one ethylenically unsaturated compound of the structure:

(H)(R⁵⁷)C＝C(R⁵⁸)(CN)

wherein R is⁵⁷Is a hydrogen atom or a cyano group; r⁵⁸Is an alkyl group of 1 to about 8 carbon atoms, CO₂R⁵⁹Radical (wherein R⁵⁹Alkyl of 1 to about 8 carbon atoms) or a hydrogen atom; and

(3) a repeating unit derived from at least one ethylenically unsaturated compound containing an acidic group.

13. The photoresist composition of claim 1, wherein the photoactive component is chemically bonded to a polymer selected from the group consisting of (a) through (e).

14. A method of preparing a photoresist image on a substrate, comprising, in order:

(X) imagewise exposing the photoresist layer to form imaged regions and non-imaged regions, wherein the photoresist layer is prepared from a photoresist composition comprising:

(A) at least two polymers selected from:

(a) a fluorine-containing copolymer comprising a repeating unit derived from at least one ethylenically unsaturated compound, characterized in that the at least one ethylenically unsaturated compound is a polycyclic compound;

(b) a branched polymer containing protected acidic groups, the polymer containing one or more branches chemically linked along a linear backbone;

(c) a fluoropolymer comprising at least one fluoroalcohol group having the structure:

-C(Rf)(Rf′)OH

wherein Rf and Rf' are the same or different fluoroalkyl groups of 1 to about 10 carbon atoms, or taken together are (CF)₂) n, wherein n is 2 to about 10;

(d) perfluoro (2, 2-dimethyl-1, 3-dioxole) or CX₂＝CY₂Wherein X ═ F or CF₃Y ═ H, or perfluoro (2, 2-dimethyl-1, 3-dioxole) and CX₂＝CY₂The amorphous vinyl copolymer of (a); and

(e) nitrile/fluoroalcohol-containing polymers prepared from substituted or unsubstituted vinyl ethers; and

(B) a photoactive component; and

(Y) developing the exposed photoresist layer with imaged areas and non-imaged areas to form a relief image on the substrate.

15. The method of claim 14, wherein the absorption coefficient of the polymer at a wavelength of about 157nm is less than about 5.0 μm^-1。

16. The method of claim 14, wherein the absorption coefficient of the polymer at a wavelength of about 157nm is less than about 4.0 μm^-1。

17. The method of claim 14, wherein the absorption coefficient of the polymer at a wavelength of about 157nm is less than about 3.5 μm^-1。