JP2018108634A - Aerosol process for manufacturing chemical mechanical planarization (CMP) polishing pads - Google Patents

Abstract

An application method or spray method is provided for producing a chemical mechanical polishing pad with improved uniformity. SOLUTION: A static mixer 12 having a nozzle 20 at a downstream end is supplied with a liquid polyol component having a temperature T1 and a liquid isocyanate component having a temperature T2, which are two components that are substantially anhydrous without solvent. Introducing separately at a low pressure of 120 kPa (1-14 psi) (this liquid polyol component comprises one or more polyols, amine curing agents; and the liquid isocyanate component comprises one or more polyisocyanates or isocyanates Including a terminal urethane prepolymer), mixing the two components in a static mixer to form a reaction mixture, draining the reaction mixture stream from a nozzle onto an open mold substrate having a urethane release surface, and curing Forming a porous polyurethane reaction product. [Selection] Figure 1

Description

  The present invention is a method of making a porous polyurethane (PU) elastomer product and a chemical mechanical planarization (CMP) polishing pad, wherein a solvent-free and substantially anhydrous binary reaction mixture is mixed in a static mixer From which it is discharged into a mold at ambient pressure and cured to form a pad, wherein the method does not inject gas into the reaction mixture and the reaction mixture is substantially foamed. It relates to a method which does not contain an agent.

Known methods for producing porous CMP polishing pads include, for example, adding a porous polymer filler to the molded polymer matrix, mechanical initiation of a gas / polyurethane (PU) mixture that cures to trap air bubbles. Foam; addition of blowing agent or use of water to create pores from physically or chemically generated gas; and rapid decompression of polymer saturated with supercritical (SC) fluid (eg, SC-CO ₂ ) included. However, in any such method, the introduction of a significant amount of gas into the pad-forming mixture necessitates conditioning it before enclosing it, and ventilation and drainage during and after processing. The need for processing increases. Known methods of generating or introducing gas to create pores in the pad-forming mixture do not create a uniform pore distribution or cannot uniformly fill the mold to produce a CMP polishing pad . Furthermore, the introduction or generation of air or gas into such a reaction mixture for producing a CMP polishing pad can result in a two-phase flow from the spray device, and thus uniformity. This can be deficient, resulting in alternating liquid and gas flows at the spray tip or nozzle, resulting in uneven material discharge and resulting streaking in the resulting product.

  U.S. Pat. No. 8,314,029 to Hirose et al. Prepared a cell-dispersed urethane-forming composition by mechanical foaming and removed the composition from a single discharge port into the central portion of the face material (from which the face material was The polyurethane can be peeled off while feeding in the direction), adjusting the thickness of the urethane-forming composition on the face material, and removing the composition without applying additional load to the composition A method of manufacturing a CMP polishing pad is disclosed that includes curing. Mechanical foaming introduces a non-reactive gas into the reaction mixture.

  The inventors have sought to solve the problem of providing a coating or spraying method for producing chemical mechanical polishing pads with improved uniformity.

DESCRIPTION OF THE INVENTION In accordance with the present invention, a method of manufacturing a chemical mechanical planarization (CMP) polishing pad includes a static mixer having a nozzle at its downstream end and a temperature T1, which is a solvent-free and substantially anhydrous two-component. A liquid polyol component having a temperature and a liquid isocyanate component having a temperature T2 are separately introduced under an absolute pressure of 100 to 200 kPa, or preferably 100 to 150 kPa, respectively, to create a flow through the mixer (this liquid polyol component is Comprising one or more polyols, an amine curing agent, preferably an aromatic diamine, and further comprising a plurality of minor elements such as polymeric microsphere beads; and the liquid isocyanate component comprises one or more polyisocyanates or isocyanate-terminated Urethane prepolymer, preferably aromatic polyisocyanate Or an aromatic isocyanate-terminated urethane prepolymer; at least one component, preferably the liquid polyol component, is in an amount sufficient to facilitate pore stabilization and is based on the total solids weight of the reaction mixture Up to 2.0% by weight or preferably 0.1 to 1.0% by weight of a nonionic surfactant, preferably an organopolysiloxane-co-polyether surfactant). Mixing the components to form a reaction mixture, preferably on a mold substrate having a urethane release surface such as polytetrafluoroethylene, the desired groove pattern of the CMP polishing pad is formed when the applied reaction mixture fills the mold. Discharging the reaction mixture stream from the nozzle onto an open mold with a female topography to form, and 1 from ambient temperature 0 ° C., or preferably cured at 100 ° C. from ambient ^{temperature, 0.6g / cm 3 ~1g / cm} 3, or preferably having a density in the range of 0.75g ^/ cm ³ ~0.95g ^/ cm 3 Forming a porous polyurethane reaction product.

  2. In accordance with the present invention, the nozzle is fitted with an atomizing air inlet or air blast cap that surrounds the outside of the nozzle so that the air flow passes through the tip of the nozzle and then the exhausted flow of reaction mixture. A method for manufacturing a CMP polishing pad according to claim 1, wherein the CMP polishing pad flows in the axial direction along the line.

  3. According to the present invention, the CMP polishing pad according to any one of the above 1 or 2, wherein the reaction mixture does not contain an added blowing agent (does not contain an added chemical or physical blowing agent). Method for manufacturing.

  4). According to the invention, the reaction mixture according to 1, 2 or 3 above, wherein the reaction mixture has a gel time of 2 to 300 seconds, or preferably 5 to 60 seconds, or more preferably 5 to 45 seconds at its curing temperature. A method for manufacturing a CMP polishing pad according to any one of the preceding claims.

  5. According to the present invention, when the liquid polyol component is introduced into the static mixer at temperature T1 and the liquid isocyanate component at temperature T2, respectively, each has a viscosity of 1-1000 cPs, or preferably 100-500 cPs, and T1 And each of T2 is in the range of 10 ° C to 80 ° C, or preferably in the range of 15 to 40 ° C, or more preferably ambient temperature, as described in any one of the above 1, 2, 3 or 4. A method for manufacturing a CMP polishing pad.

  6). According to the present invention, there is further provided a CMP polishing pad according to claim 5 wherein each of the liquid polyol component and the liquid isocyanate component is separately preheated to temperatures T1 and / or T2, respectively, before being introduced into the static mixer. Method for manufacturing.

  7). According to the present invention, the liquid polyol component further comprises one of the minor elements, such as polymer microspheres, or up to 3000 ppm, or preferably up to 1500 ppm water, to increase the porosity of the pad. A method for producing a CMP polishing pad according to any one of 2, 3, 4, 5 or 6.

  8). According to the invention, the CMP polishing pad according to any one of 1, 2, 3, 4, 5, 6 or 7 is produced, wherein the reaction mixture is solvent-free and substantially anhydrous. How to do.

  9. According to the invention, the curing of the reaction mixture is first cured from ambient temperature to 130 ° C. for 1 to 30 minutes, or preferably 30 seconds to 5 minutes, the polyurethane reaction product is removed from the mold, Any of the above 1-8, comprising finally curing at a temperature of 60-130 ° C. for 1 minute to 16 hours, or preferably 5 minutes to 15 minutes to form a porous product. A method for manufacturing the described CMP polishing pad.

  10. According to the present invention, the formation of the polishing pad is performed by laminating a subpad layer, such as a polymer-impregnated nonwoven sheet, or a porous or non-porous polymer sheet, on the bottom side of the porous product, thereby forming a porous product molding surface. The method of claim 10, further comprising: forming a top surface of the CMP polishing pad.

  11. According to the present invention, the discharge of the reaction mixture stream into the mold can be performed by overspraying the mold, followed by curing of the reaction mixture thus applied to form a polyurethane reaction product, 11. A method according to any one of the preceding claims comprising removing the product and then stamping or cutting the polyurethane reaction product to the desired diameter of the CMP polishing pad.

  12 In accordance with the present invention, a static mixer including a nozzle at its downstream end has a mechanical actuator operable in a plane parallel to the surface of the open mold, for example, a mechanical linkage that allows programmed operation. The above-mentioned items 1 to 11, which are held in place by a programmable electronic actuator, preferably a robot having a four-axis arm operable in the XY-axis direction or a six-axis arm capable of XYZ-axis movement and rotation The method according to any one of the above. For purposes herein, formulations are expressed in weight percent unless otherwise specified.

  Unless otherwise noted, temperature and pressure conditions are ambient temperature and standard pressure (101 kPa).

  Unless otherwise specified, a term including parentheses alternatively refers to the entire term when no parentheses are present, a term excluding the parentheses, and combinations of options. Thus, the term “(poly) isocyanate” refers to isocyanates, polyisocyanates, or mixtures thereof.

  All ranges include extreme values and can be combined. For example, the term “range of 50-3000 cPs, or 100 cPs or more” will include 50-100 cPs, 50-3000 cPs, and 100-3000 cPs, respectively.

  Unless otherwise indicated, as used herein, the term “average molecular weight” of a polymer is used to indicate the appropriate indicator known (such as poly (ethylene glycol) for polyols in the absence of an indicator). It means the result obtained by gel permeation chromatography with respect to (standard substance).

  As used herein, the term “gel time” refers to a VM-2500 vortex lab mixer (StateMix Ltd., Winnipeg, Canada) set a given reaction mixture at about 80 ° C., eg, 1000 rpm. ) For 30 seconds, set the timer to zero, turn the timer on, pour the mixture into an aluminum cup and set the gel timer hotpot (Gardco Hot Pot ™ Gel Timer, Paul N. Gardner Company) at 65 ° C. , Inc., Pampano Beach, FL), meaning the result obtained by stirring the reaction mixture with a wire stirrer at 20 RPM and recording the gel time when the wire stirrer stops moving in the sample. Do

  As used herein, the term “ASTM” refers to publications of ASTM International, West Conshohocken, PA.

  As used herein, the term “polyisocyanate” means any isocyanate group that contains a molecule that contains two or more isocyanate groups.

  As used herein, the term “polyurethane” refers to polymerization products from difunctional or polyfunctional isocyanates such as polyether urea, polyisocyanurate, polyurethane, polyurea, polyurethane urea, copolymers thereof. And a mixture thereof.

  As used herein, the term “reaction mixture” refers to the hardness of polyurethane reaction products in CMP polishing pads according to any non-reactive additive such as trace elements and ASTM D 2240-15 (2015). Includes any additive that lowers.

As used herein, the term “stoichiometry” of a reaction mixture refers to the ratio of the molar equivalents of (free OH + free NH ₂ groups) to free NCO groups in the reaction mixture.

  As used herein, the term “SG” or “specific gravity” refers to the ratio of the density of a polishing pad or layer made according to the present invention to the density of water at the same temperature.

  As used herein, the term “solids” refers to any material remaining in the polyurethane reaction product of the present invention, so that the solids are reactive and non-volatile that do not volatilize upon curing. Contains additives. Solids exclude water and volatile solvents.

  As used herein, unless stated otherwise, the term “substantially anhydrous” means that the amount of water added to a given composition is less than 2000 ppm, or preferably zero, and the composition This means that the amount of water added to the substance constituting the component is less than 2000 ppm, or preferably 0. A “substantially anhydrous” reaction mixture can contain water present in the feed in the range of 50-2000 ppm or from the ambient water where the reaction water or reaction mixture formed in the condensation reaction is used. Steam can be included.

  As used herein, the term “substantially free of blowing agent” means that a given composition contains no added chemical or physical blowing agent. The blowing agent does not contain water. The air flow through the nozzle is not considered part of a given composition.

  As used herein, unless otherwise specified, the term “viscosity” is measured using a rheometer set at a constant shear of 1 radians / second in a 50 mm parallel plate shape with a 100 μm gap. Refers to the viscosity of a given substance in neat form (100%) at temperature.

  As used herein, the term “wt% (wt.%)” Represents weight percent.

FIG. 1 shows a perspective view of an apparatus for use in the method of the present invention.

  The present invention is for producing a porous polyurethane CMP polishing pad from a two-component reaction mixture without generating a foam and avoiding gas injection by generating an aerosol after the liquid reaction mixture is discharged from the mixer outlet. Enables a simple spray application method. The only gas used in the method of the present invention is ambient air. The pressure at which the fluid reaction mixture is formed and applied to the open mold ranges from up to 200 kPa (at the static mixer inlet) to ambient pressure (at the static mixer downstream outlet). The method of the present invention creates porosity by discharge into an open mold and subsequent confinement of ambient air by the reaction mixture stream. Thus, in the absence of trace elements or polymer microspheres, the trapped air forms pores having an average pore diameter in the range of 5-100 μm, or preferably 10-40 μm. The low pressure of the process of the present invention makes it possible to include trace elements or collapsible pore-forming additives in the binary reaction mixture. Furthermore, the simplicity and open mold nature of the process of the present invention makes the reaction mixture harden very quickly, such as having a gel time of 5 to 45 seconds, or a more gradual gel time of up to 300 seconds. It makes it possible to use a wider range of reaction mixtures that react. Furthermore, the method of the present invention decouples the intensity or pressure of mixing from the degree of spraying of the reaction mixture produced during discharge, so that the average pore size from a well-mixed reaction mixture is greater than 20 μm, Alternatively, it is possible to form a molded product exceeding 40 μm, that is, a CMP polishing pad. Finally, the low viscosity of the method of the present invention and the two-component reaction mixture together allow for excellent mold filling and reproducibility of the mold surface in the molded article, ie the CMP polishing pad surface. The apparatus used in the method of the present invention is supplied by two reeds (one liquid isocyanate component, the other liquid polyol component) via a pump such as a peristaltic pump or a positive displacement piston pump, and atomizing air. Includes a simple static mixer with a downstream spray nozzle fitted with a cap. The static mixer operates from a maximum of 200 kPa (at the static mixer inlet) to ambient pressure (at the static mixer outlet).

  The spray nozzle of the present invention can be a simple conical nozzle fitted with a source of atomizing air surrounding the outside of the nozzle, for example an air blast cap or an atomizing air inlet. The air blast cap is placed on the nozzle base and, together with the outside of the nozzle base, forms an annular gap that causes ambient air to flow to the tip of the nozzle and then axially along the flow of the discharged reaction mixture Flow onto the substrate. Suitable air blast caps and nozzles are available from Nordson EFD. , Providence, RI.

  The air flow rate through the air blast cap or atomizing air inlet is in the range of 20-180 L / min, or preferably 30-150 L / min.

  One suitable device consists of two parts. A metering pump that supplies a controlled ratio of liquid polyol component and liquid isocyanate component from a holding tank to a static mixer, and a static mixer equipped with an air blast aerosolization tip that blends and sprays the reaction mixture onto the substrate. is there.

  In the apparatus of the present invention, the two leads to the static mixer are like a pair of pneumatically driven positive displacement piston pumps for dispensing a liquid polyol component or liquid isocyanate component, respectively, through a series of parts and conduits into the static mixer. Various metering or delivery systems. The A / B ratio is controlled via a lever arm that mechanically changes the relative motion of the two piston pumps. An example of this device is commercially available as a Posiatio ™ Mini PRM meter (Graco, Minneapolis, Minn.). Another example is two laboratory grade peristaltic pumps for delivering a liquid isocyanate component and a liquid polyol component, respectively, to a static mixer.

  As shown in FIG. 1, the static mixer (12) has two fluid inlet leads (16 and 18) for the liquid isocyanate component and the liquid polyol component, respectively. The static mixer (12) has, at its downstream end, a nozzle (20) fitted with an air blast cap (14) for assisting spraying of the spray from the nozzle (20).

  The reaction mixture of the present invention contains no solvent and no added water except that up to 2000 ppm water can be added to the liquid polyol component to facilitate pore formation.

  The mold of the present invention is made of a non-stick material such as polytetrafluoroethylene or is lined. Preferably, the mold is machined to form a female topography so that the resulting molded polyurethane reaction product has the desired groove shape.

  Preferably, the substrate in the method of the present invention is a mold having a groove pattern that directly incorporates the CMP polishing pad to be manufactured. For example, the mold can have a female topography that forms a pad groove pattern when the applied reaction mixture fills the mold.

  The liquid isocyanate component of the present invention can include any of diisocyanates, triisocyanates, isocyanurates, isocyanate terminated urethane prepolymers, or mixtures thereof. Preferably, the liquid isocyanate component is methylene diphenyl diisocyanate (MDI); toluene diisocyanate (TDI); naphthalene diisocyanate (NDI); paraphenylene diisocyanate (PPDI); o-toluidine diisocyanate (TODI); modified diphenylmethane diisocyanate (carbodiimide-modified diphenylmethane diisocyanate). Aromatic diisocyanates selected from allophanate-modified diphenylmethane diisocyanates, biuret-modified diphenylmethane diisocyanates, etc .; aromatic isocyanurates such as MDI isocyanurates; Polymer or one or more isocyanate groups Such as MDI dimer containing Sutenda include aromatic isocyanates.

  Suitable isocyanate extenders are: ethylene glycol; 1,2-propylene glycol; 1,3-propylene glycol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3-propanediol; 4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; tripropylene glycol, and mixtures thereof.

  The liquid isocyanate component of the present invention can have a very high unreacted isocyanate (NCO) concentration of 10 to 40 wt%, or preferably 15 to 35 wt%, based on the total solids weight of the aromatic isocyanate component. .

  Suitable isocyanate-terminated urethane prepolymers are isocyanate-terminated urethane prepolymers, preferably having a free toluene diisocyanate (TDI) monomer content of less than 0.1% by weight.

  The liquid polyol component of the present invention is any one or more diols or polyether polyols having terminal hydroxyl groups, such as diols, polyols, polyol diols, copolymers thereof and mixtures thereof. be able to. Preferably, the one or more polyols are polyether polyols (eg, poly (oxytetramethylene) glycol, poly (oxypropylene) glycol and mixtures thereof); polycarbonate polyols; polyester polyols; polycaprolactone polyols; And one or more low molecular weight polyols (ethylene glycol; 1,2-propylene glycol; 1,3-propylene glycol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3 1,4-butanediol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; and tripropylene It is selected from the mixture of selected from the group consisting of recall).

  More preferably, the one or more polyols of the liquid polyol component of the present invention are polytetramethylene ether glycol (PTMEG); ester-containing polyols (ethylene adipates, butylenes adipate, etc.); polypropylene ether glycols (PPG) ); Polycaprolactone polyols; copolymers thereof; and mixtures thereof.

Suitable polyols may include a polyol having a number average molecular weight _{M N} of 500 to 10,000. Preferably, the polyol used is 500～6,000, or more preferably 500 to 4,000; and most preferably have a number average molecular weight _{M N} of 1,000 to 2,000. Such high molecular weight polyols preferably have an average of 3 to 10 hydroxyl groups per molecule. More preferably, the high molecular weight polyol used has an average of 4-8, or more preferably 5-7, or most preferably 6 hydroxyl groups per molecule. An example of a high molecular weight polyol containing 6 hydroxyl groups is a polypropoxy-co-ethoxy sugar alcohol, such as sorbitol, having ethoxy hydroxyl groups.

  The amine curing agents of the present invention are amines or polyamines having one or more, or preferably two or more amine groups, or preferably aromatic diamines and aromatic polyamines having three amine groups. It is an aromatic polyamine. More preferably, the aromatic polyamine is dimethylthiotoluenediamine; trimethylene glycol di-p-aminobenzoate; polytetramethylene oxide di-p-aminobenzoate; polytetramethylene oxide mono-p-aminobenzoate; polypropylene oxide di- Polypropylene oxide mono-p-aminobenzoate; 1,2-bis (2-aminophenylthio) ethane; toluenediamines (diethyltoluenediamine, 5-tert-butyl-2,4-toluenediamine, 3 -Tert-butyl-2,6-toluenediamine, 5-tert-amyl-2,4-toluenediamine, 3-tert-amyl-2,6-toluenediamine, 5-tert-amyl-2,4-chlorotoluene Zia And tert-amyl-2,6-chlorotoluenediamine); methylenedianilines (such as 4,4′-methylene-bis-aniline); isophoronediamine; 1,2-diaminocyclohexane; bis (4 -Aminocyclohexyl) methane; 4,4'-diaminodiphenylsulfone; m-phenylenediamine; xylenediamines; 1,3-bis (aminomethylcyclohexane); and mixtures thereof, preferably dimethylthiotoluene Diamine.

In general, the stoichiometric ratio of the total number of moles of amine (NH ₂ ) groups and the total number of moles of hydroxyl (OH) groups in the reaction mixture to the total number of moles of unreacted isocyanate (NCO) groups in the reaction mixture is 0.8: 1.0 to 1.1: 1.0, or preferably 0.95 to 1.05.

  The CMP polishing pad of the present invention can further include a plurality of trace elements that are preferably uniformly distributed throughout the polishing layer. Preferably, the microelements are selected from hollow core polymer materials such as polymer microspheres, liquid filled hollow core polymer materials such as fluid filled polymer microspheres, water soluble materials and insoluble phase materials (eg mineral oil). . More preferably, the microelements are selected from hollow core polymer materials. Preferably, the microelements have a weight average diameter of less than 150 μm, or more preferably less than 100 μm, most preferably 5-50 μm. Preferably, the plurality of microelements comprise polymer microspheres having a shell wall of either polyacrylonitrile or polyacrylonitrile copolymer (eg, Expandel ™ beads from Akzo Nobel, Amsterdam, Netherlands). When used, the amount of microelements is from the amount necessary to create a porosity of 0.1 to 50% by volume, or preferably 5 to 35% by volume, in the CMP polishing pad or polishing layer. It can be a range. The term “porosity” refers to the volume concentration of the trace element divided by the volume of the resulting CMP polishing pad or layer.

  The chemical mechanical polishing pad produced by the method of the present invention may simply comprise a polishing layer of polyurethane reaction product, or a polishing layer laminated to a subpad or sublayer. In the case of the polishing pad of the present invention, or laminated pad, the polishing layer of the polishing pad is useful in both porous and non-porous or unfilled shapes.

  Preferably, the polishing layer used in the chemical mechanical polishing pad of the present invention is 500-3750 microns (20-150 mils), or more preferably 750-3150 microns (30-125 mils), or even more preferably. Has an average thickness of 1000 to 3000 microns (40 to 120 mils), or most preferably 1250 to 2500 microns (50 to 100 mils).

  The chemical mechanical polishing pad of the present invention further comprises at least one additional layer optionally in contact with the polishing layer. Preferably, the chemical mechanical polishing pad further comprises a compressible subpad or base layer optionally adhered to the polishing layer. This compressible base layer preferably improves the compatibility of the polishing layer to the surface of the substrate being polished.

  The polishing layer of the chemical mechanical polishing pad of the present invention has a polishing surface adapted to polish the substrate. Preferably, the polishing surface has a macrotexture selected from at least one of perforations and grooves. The perforations may extend from the polishing surface to the middle of the thickness of the polishing layer or to the whole.

  Preferably, the grooves are arranged on the polishing surface so as to sweep over the surface of the substrate on which at least one groove is being polished by rotation of a chemical mechanical polishing pad during polishing.

  Preferably, the polishing layer of the chemical mechanical polishing pad of the present invention is a polishing surface adapted to polish a substrate and is selected from and formed in curved grooves, linear grooves, perforations and combinations thereof. A polishing surface having a macrotexture including a groove pattern. Preferably, the groove pattern includes a plurality of grooves. More preferably, the groove pattern is concentric grooves (which may be circular or spiral), curved grooves, oblique parallel grooves (eg, arranged as an XY grid across the pad surface), other It is selected from groove designs such as those selected from the group consisting of regular designs (eg, hexagons, triangles), tire tread type patterns, irregular designs (eg, fractal patterns), and combinations thereof. More preferably, the groove design is selected from the group consisting of random grooves, concentric grooves, spiral grooves, oblique parallel grooves, XY lattice grooves, hexagonal grooves, triangular grooves, fractal grooves and combinations thereof. Most preferably, the polishing surface has a spiral groove pattern formed therein. The groove profile is preferably selected from rectangular and straight sidewalls, or the cross section of the groove can be “V” shaped, “U” shaped, serrated, and combinations thereof.

  In the method of manufacturing a polishing pad according to the present invention, the chemical mechanical polishing pad promotes slurry flow and provides a macrotexture or groove pattern on its polishing surface to remove polishing debris from the pad-wafer interface. Can be shaped to have. Such grooves may be formed in the polishing surface of the polishing pad from the shape of the mold surface (ie, the mold now has a macro-textured female topography plate).

  The chemical mechanical polishing pad of the present invention can be used to polish a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate.

  The CMP polishing pad of the present invention is effective for polishing an interlayer insulating film (ILD) and an inorganic oxide.

  Preferably, the method of polishing a substrate of the present invention comprises preparing a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate (preferably a semiconductor substrate such as a semiconductor wafer); Providing a mechanical mechanical polishing pad; creating dynamic contact between the polishing surface of the polishing layer and the substrate to polish the surface of the substrate; and conditioning the polishing surface using an abrasive conditioner including.

  Polishing pad conditioning can occur during intermittent interruptions ("ex situ" in the CMP process where polishing is paused) or while the CMP process is ongoing ("in situ"). One of them includes contacting the conditioning disk with a polishing surface, which typically has diamond points embedded in the pad surface to cut fine wrinkles to both wear and dig up the pad material for polishing. It has a rough conditioning surface that updates the texture, typically the conditioning disk is rotated in a fixed position relative to the axis of rotation of the polishing pad, and sweeps the annular conditioning area as the polishing pad rotates.

  The mixer / aerosol assembly is a Nordson Series 160AA disposable static mixer equipped with a Nordson Air Cap ™ air blast assembly (Nordson EFD, Providence, RI). An air cap assembly, commonly known as an air blast nozzle, is designed to fit the end of a static mixer having a nozzle of a given orifice size. The air blast nozzle is fed immediately downstream of the static mixer nozzle by a high speed gas supply (eg, nitrogen or air) and aerosolizes the PU mixture as it exits the end of the static mixer. Both the static mixer and the air cap assembly are disposable. The compositions used for spraying to make a CMP polishing pad are shown in Tables 1 and 2 below. All amounts in Tables 1 and 2 are parts by weight as solids.

  A series having a female topography that pumps the composition to a static mixer at 110 kPa absolute pressure, mixes in the static mixer and produces a 3 mm base thickness CMP polishing pad, and extends from the base pad Was applied at ambient pressure to a 570 mm diameter polytetrafluoroethylene mold having a macrotexture in the shape of an annular concentric elongated rectangular protrusion (having a cross-sectional dimension of a protrusion of 1.25 mm width and 0.8 mm height) . The spray fluid flow rate was controlled by the pump speed entering the static mixer.

[Example 1]
The composition of Table 1 was sprayed at an air blast gas flow rate of 141.6 L / min, cured at 100 ° C. for 14 hours, and released. Analysis of the cross-sectional image of the resulting product showed that the average pore diameter was constant from the top to the bottom of the sample, and there were few large bubbles and none exceeding 100 μm. The average pore diameter of the cross section was 27 μm. The pore diameter should preferably be 40 μm or less.

[Examples 2A and 2B]
The composition of Table 2 above was sprayed at an air blast gas flow rate ranging from 0 to 141.6 L / min. Table 3 below lists the final product density and measured average pore size for the composition at various spray air flow rates.
Test method: The resulting molded product was tested as follows, and the results are shown in Table 2 below.
Image analysis: An insight into the average pore size was obtained by scanning electron micrograph (SEM) of the resulting molded article. An image (not shown) used for image analysis was a cross section of a designated molded product from the top to the bottom (image 1 = top, image 4 = bottom).
Density was measured by the Archimedes method, which compares the weight of a given part with the weight when immersed in water.
The average pore diameter was measured by image manual analysis of a selected number of pores (250 to 300 pores), and the pore diameter of each selected pore was determined and averaged.

  As shown in Table 3 above, the gas flow rate through the air blast cap was critical to achieving a small average pore size and the desired porosity. If the gas flow rate is too low, the resulting fluid spray is too coarse and / or too slow to create a properly sized bubble upon impact with the surface. Therefore, according to the present invention, the porosity and average pore diameter of the CMP polishing pad can be changed simply by changing the gas flow rate of the air blast cap in the apparatus. That is, in Example 2A, very large pores can also be formed by thorough mixing in a static mixer, and the pore size of the applied and cured polyurethane reaction product is determined by mixing with a static mixer. Independent of quantity or quality.

Regarding the average pore diameter, Table 2 above shows that when the flow rate is decreased from 141.6 liters / minute (L / minute) to 56.6 L / minute, the average pore diameter increases dramatically, and the number of pores increases. Indicates a drop. Based on these data, an air flow rate of 85 L / min is preferred and 141.6 L / min is most preferred to achieve the desired CMP polishing pad average pore size. The density of the molded product is inversely proportional to the gas flow rate, from approximately 0.8 g / cm ³ at the maximum gas flow rate to approximately 0.95 g / cm ³ at the minimum gas flow rate. Compositions containing trace elements provide a preferred range of densities and average pore sizes for CMP polishing pads.

  As shown in Table 3 above, the method of the present invention allows the pores to be sprayed by spraying the reaction mixture, by entrapping ambient air as demonstrated above, or through the addition of polymer microspheres. Can be generated. In the product sprayed with the microspheres of Example 2, the microspheres produce the majority of the observed pores. This is evidence of excellent control over porosity and its predictability. The uniformity of the average pore size at the top line indicates that the microspheres remained intact throughout the entire process. The product of Example 1, which does not contain polymer microspheres, has a similar density and has pores derived solely from trapped air, which is evidence of the flexibility of the method of the present invention.

Claims (10)

A method of forming a chemical mechanical planarization (CMP) polishing pad comprising:
In a static mixer having a nozzle at the downstream end thereof, a solvent-free and substantially anhydrous two component of a liquid polyol component having a temperature T1 and a liquid isocyanate component having a temperature T2 are each subjected to an absolute pressure of 100 to 200 kPa Separately introduced (the liquid polyol component comprises one or more polyols, amine curing agents; and the liquid isocyanate component comprises one or more polyisocyanates or isocyanate-terminated urethane prepolymers; at least one component Is sufficient to facilitate pore stabilization and contains no more than 2.0 wt% nonionic surfactant based on the total solids weight of the reaction mixture)
Mixing the two components in a static mixer to form a reaction mixture;
Possible to discharge the flow of the reaction mixture at ambient pressure from a nozzle onto a mold substrate having a urethane release surface, and cured at 130 ° C. from ambient temperature, density in the range of 0.6g ^/ cm ³ ~1g / cm 3 Forming a porous polyurethane reaction product having:   The nozzle is fitted with an atomizing air inlet or air blast cap that surrounds the outside of the nozzle so that the air flow passes through the nozzle tip and then axially along the discharged flow of the reaction mixture. The method of claim 1, wherein the method flows.   The method of claim 1, wherein the reaction mixture does not contain added chemical or physical blowing agents.   The method of claim 1, wherein the reaction mixture has a gel time of 2 to 300 seconds at its curing temperature.   The method according to claim 1, wherein when the liquid polyol component is introduced into the static mixer at a temperature T1 and the liquid isocyanate component at a temperature T2, respectively, each has a viscosity of 1 to 1000 cPs.   The method according to claim 1, wherein in the liquid polyol component, the amine curing agent is an aromatic diamine.   The method of claim 1, wherein the liquid polyol component further comprises a plurality of trace elements.   The method of claim 1, wherein in the liquid isocyanate component, the isocyanate comprises an aromatic polyisocyanate or an aromatic isocyanate-terminated urethane prepolymer.   The method of claim 1, wherein the mold substrate comprises an open mold having a female topography that forms a desired groove pattern of a CMP polishing pad when the applied reaction mixture fills the mold. Curing of the reaction mixture is
First curing from ambient temperature at 130 ° C. for 1-30 minutes,
The method of claim 1, comprising removing the polyurethane reaction product from the mold and then finally curing at a temperature of 60-130 ° C for a period of 1 minute to 16 hours to form a porous product.

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