JP2010041056A - Chemical mechanical polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad having a high removing speed and capable of polishing semiconductor materials such as copper, an insulator, a barrier, and a tungsten wafer. <P>SOLUTION: The polishing pad includes a polymeric matrix and hollow polymeric particles, wherein the polymeric matrix is a polyurethane reaction product of a curing agent and an isocyanate-terminated polytetramethylene ether glycol at an NH<SB>2</SB>to NCO stoichiometric ratio of 80 to 97%. The isocyanate-terminated polytetramethylene ether glycol has an unreacted NCO range of 8.75 to 9.05 wt.%. The hollow polymeric particles have an average diameter of 2 to 50 μm and a wt.%<SB>b</SB>and density<SB>b</SB>of constituents forming the polishing pad as the shown formula (1) wt.%<SB>a</SB>*density<SB>b</SB>/density<SB>a</SB>=wt.%<SB>b</SB>. In the formula (1), density<SB>a</SB>is equal to 60g/l, the density<SB>b</SB>is 5 to 500 g/l, and a wt.%<SB>a</SB>is 3.25 to 4.25 wt.%. The polishing pad has a porosity of 30 to 60 vol.%, and a cell structure in the polymeric matrix forms a continuous network surrounding the cell structure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

BACKGROUND This specification relates to a polishing pad useful for polishing or planarizing a semiconductor substrate. Semiconductor manufacturing generally includes several chemical mechanical polishing (CMP) steps. In each CMP step, the polishing pad is combined with a polishing solution, such as an abrasive-containing polishing slurry or an abrasive-free reactive liquid, such that it is planarized or remains flat for subsequent layer acceptance. Remove excess material in a manner. These stacks of layers combine in such a way as to form an integrated circuit. The manufacture of these semiconductor devices continues to become more complex due to the demand for devices that increase operating speed, reduce leakage current, and reduce power consumption. In terms of device architecture, this can be paraphrased as a finer geometry and an increased number of metallization layers. These increasingly stringent device design requirements are driving the adoption of increasingly smaller line spacings and corresponding increases in pattern density. The smaller scale and increased complexity of the device has led to greater demands on CMP consuming materials such as polishing pads and polishing solutions. In addition, as integrated circuit feature sizes shrink, CMP-induced defects, such as scratches, become a greater problem. In addition, the reduction in integrated circuit film thickness requires an improved defect rate while providing an acceptable topography for the wafer substrate. These topography requirements require an increasingly strict flatness, line dishing and polishing specifications that result in small shapes of all yellow.

  Traditionally, cast polyurethane polishing pads have been provided with mechanical integrity and chemical resistance for most polishing processes used to manufacture integrated circuits. For example, polyurethane polishing pads have sufficient tensile strength and elongation to resist tearing, wear resistance to avoid wear problems during polishing, and resistance to corrosion by strongly acidic and strong caustic alkaline polishing solutions. Stability. Unfortunately, hard cast polyurethane polishing pads that tend to improve planarization, at the same time, tend to increase defects.

  M. J. Kulp, in US Pat. No. 7,169,030, discloses a series of polyurethane polishing pads having high tensile modulus. These polishing pads provide excellent planarization and defect rates for some combinations of polishing pads and polishing slurries. For example, these polishing pads can provide superior polishing performance for silicon oxide / silicon nitride polishing applications such as direct shallow trench isolation (STI) polishing applications with ceria-containing polishing slurries. . As used herein, silicon oxide refers to silicon oxides, silicon oxide compounds and doped silicon oxide blends useful for forming insulators in semiconductor devices, and silicon nitride refers to nitridation useful for semiconductor applications. Refers to silicon, silicon nitride compounds and doped silicon nitride blends. Unfortunately, these pads do not have the versatility to improve polishing performance with any polishing slurry with respect to the large number of substrate layers included in present and future semiconductor wafers. Furthermore, further enhancements in polishing performance are still required as the cost of semiconductor devices decreases.

  Increasing the removal rate of the polishing pad can reduce the equipment installation area and cost of the semiconductor manufacturing plant by increasing the throughput. Because of this demand for performance enhancement, there is still a need for a polishing pad for removing a substrate layer with enhanced performance. For example, the oxide insulator removal rate is important for removing an insulator in polishing an interlayer dielectric (“ILD”) or inter-wiring dielectric (“IMD”). Specific types of insulator oxides used include TEOS formed from BPSG, decomposition of tetraethylorthosilicate, HDP (“high density plasma”) and SACVD (“low pressure chemical vapor deposition”). There remains a need for polishing pads that combine acceptable defect rate performance and wafer uniformity with increased removal rates. In particular, there is a need for a polishing pad suitable for ILD polishing that combines acceptable planarization and defect rate polishing performance with an accelerated oxide removal rate.

DESCRIPTION OF THE INVENTION The present invention is a polishing pad suitable for polishing a patterned semiconductor substrate comprising at least one of copper, insulator, barrier, and tungsten, the polishing pad comprising a polymer matrix and a polymer matrix. And a polymer matrix is a polyurethane reaction product having a stoichiometric ratio of NH _{2 to} NCO of 80-97% in a curing agent and an isocyanate-terminated polytetramethylene ether glycol, The tetramethylene ether glycol has an unreacted NCO range of 8.75 to 9.05% by weight and the curing agent includes a curing agent amine that cures the isocyanate terminated polytetramethylene ether glycol to form a polymer matrix, and is hollow The polymer particles are 2 to As it follows as a weight% _b and density _b of the average diameter and component forming the polishing pad of 0μm

(Where
The density _a is equal to the average density of 60 g / l,
Density _b is an average density of 5 g / l to 500 g / l,
(% By weight _a is 3.25 to 4.25% by weight)
The polishing pad has a porosity of 30-60% by volume, and the closed cell structure in the polymer matrix forms a continuous network surrounding the closed cell structure.

Another embodiment of the present invention is a polishing pad suitable for polishing a patterned semiconductor substrate comprising at least one of copper, an insulator, a barrier, and tungsten, the polymer matrix and within the polymer matrix And a polymer matrix is a polyurethane reaction product having a stoichiometric ratio of NH _{2 to} NCO of 80-90% in a curing agent and an isocyanate-terminated polytetramethylene ether glycol, and an isocyanate-terminated polytetra A hollow polymer in which the methylene ether glycol has an unreacted NCO range of 8.75 to 9.05% by weight and the curing agent comprises a curing agent amine that cures the isocyanate-terminated polytetramethylene ether glycol to form a polymer matrix. Particles are 2-50μm As it follows as a weight% _b and density _b of the average diameter and components forming the abrasive pad

(Where
The density _a is equal to the average density of 60 g / l,
The density _b is an average density of 10 g / l to 300 g / l,
(% By weight _a is 3.25 to 3.6% by weight)
And the polishing pad has a porosity of 35-55% by volume, and the closed cell structure in the polymer matrix forms a continuous network surrounding the closed cell structure.

It is a scanning electron micrograph after 250 times polishing of the polishing surface of the pad of the present invention. It is a scanning electron micrograph after 500 times polishing of the polishing surface of the pad of the present invention. FIG. 3 is a 500 × EDS image of the same area of FIG. 2 of the polishing pad of FIGS. 1 and 2 showing high silicon concentration after polishing with a silica-containing polishing slurry.

DETAILED DESCRIPTION The present invention provides a polishing pad comprising a polymer matrix suitable for planarizing at least one of semiconductor, optical and magnetic substrates. The polishing pad is particularly suitable for polishing and planarizing an ILD insulating material, as in interlayer dielectric (ILD) applications, but can also be used to polish metals such as copper or tungsten. The pad provides an increased removal rate over the conventional pad (especially during the first 30 seconds of polishing). The accelerated response of the pad in the early part of polishing allows for increased wafer throughput by reducing the polishing time required to remove a specified amount of material from the wafer surface.

  For ILD polishing using fumed silica, the removal rate can exceed 3750 kg / min in 30 seconds. Furthermore, the present invention can provide a removal rate that is at least 10% higher than that obtained with an IC1010 ™ polyurethane polishing pad in 30 seconds in the same polishing test (IC1010 is Rohm and Haas or its Is a trademark of an affiliated company). Advantageously, the removal rate in 30 seconds of the polishing pad of the present invention when polishing a TEOS sheet wafer using silica-containing abrasive grains is such that IC1000 polishing when polishing a TEOS sheet wafer using silica-containing abrasive grains More than the removal speed of the pad at 30 and 60 seconds. IC1000 ™ includes aliphatic isocyanates that tend to impart thermoplasticity to parts made from the contents, so the TEOS removal rate can be increased with respect to polishing time (IC1000 is Rohm and Haas or its Is a trademark of an affiliated company). The thermoplasticity of the IC1000 polishing pad appears to promote increased contact between the polishing pad and the wafer with increasing removal rate until some maximum value in removal rate occurs. Increasing the pad / wafer contact area to a higher level would reduce the removal rate as the local asperity / wafer contact pressure decreases. Similarly, formulations that do not contain aliphatic isocyanates have higher thermoplasticity as the degree of crosslinking or molecular weight decreases, and can exhibit a further increase in removal rate with respect to wafer polishing time. However, the pads of the present invention have a sufficient level of porosity to maximize the pad / wafer contact very early in the polishing process, and a relatively high level of crosslinkability facilitates the polishing process. It seems to provide sufficient local stiffness to the pad.

  Although the removal rate can increase with abrasive content, the improvement over the removal rate of the 1C1010 polishing pad, independent of the abrasive level, represents a significant advance in polishing performance. For example, this can facilitate increasing the removal rate with a low defect rate and reduce slurry cost. In addition to removal rate, wafer scale non-uniformity represents an important polishing performance consideration. In general, the wafer scale non-uniformity should be less than 6% because the uniformity of the polished wafer is important to obtain the maximum number of well polished dies.

  In the context of the present specification, “polyurethane” is a product derived from a difunctional or polyfunctional isocyanate, such as polyether urea, polyisocyanurate, polyurethane, polyurea, polyurethane urea, copolymers thereof and mixtures thereof. A cast polyurethane polishing pad is suitable for planarizing semiconductor, optical and magnetic substrates. The specific polishability of the pad results in part from the prepolymer reaction product of the prepolymer polyol and the polyfunctional isocyanate. To form the polishing pad, the prepolymer product is cured with a curing agent selected from the group comprising a curing agent polyamine, a curing agent polyol, a curing agent alcohol amine, and mixtures thereof. It has been found that controlling the ratio of curing agent to unreacted NCO in the prepolymer reaction product can improve the defect rate performance of the porous pad during polishing.

  Urethane production involves the preparation of isocyanate-terminated urethane prepolymers from polyfunctional aromatic isocyanates and prepolymer polyols. The prepolymer polyol is polytetramethylene ether glycol [PTMEG]. Exemplary polyfunctional aromatic isocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, tolidine diisocyanate, p-phenylene diisocyanate, xylylene. There are range isocyanates and mixtures thereof. Polyfunctional aromatic isocyanates contain less than 20% by weight of aliphatic isocyanates such as 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate and cyclohexane diisocyanate. The polyfunctional aromatic isocyanate preferably contains less than 15% by weight of aliphatic isocyanate, more preferably less than 12% by weight.

  Generally, the prepolymer reaction product is reacted or cured with a curing agent amine, such as a polyamine or a polyamine-containing mixture. For example, polyamines can be mixed with alcohol amines or monoamines. For purposes of this specification, polyamines include diamines and other multifunctional amines. Exemplary curing agent polyamines include aromatic diamines or polyamines such as 4,4'-methylene-bis-o-chloroaniline [MBCA], 4,4'-methylene-bis- (3-chloro-2,6 -Diethylaniline) [MCDEA], dimethylthiotoluenediamine, trimethylene glycol di-p-aminobenzoate, polytetramethylene oxide di-p-aminobenzoate, polytetramethylene oxide mono-p-aminobenzoate, polypropylene oxide di-p -Aminobenzoate, polypropylene oxide mono-p-aminobenzoate, 1,2-bis (2-aminophenylthio) ethane, 4,4'-methylene-bis-aniline, diethyltoluenediamine, 5-tert-butyl-2, 4- and 3-tert-butyl-2,6- Ruenjiamin, there is 5-tert-amyl-2,4- and 3-tert-amyl-2,6-toluenediamine and chlorotoluene diamine. MBCA addition represents a preferred curing agent amine. In some cases, it is also possible to produce urethane polymers for polishing pads in a single mixing step that avoids the use of prepolymers.

  The components of the polymer used to make the polishing pad are preferably selected so that the resulting pad morphology is stable and easily reproducible. For example, when 4,4'-methylene-bis-o-chloroaniline [MBCA] is mixed with a diisocyanate to form a polyurethane polymer, it is often advantageous to control the levels of monoamines, diamines and triamines. Controlling the proportions of mono, di and triamine contributes to maintaining the chemical ratio and resulting polymer molecular weight within a consistent range. In addition, for consistent manufacturing, it is often important to control additives such as antioxidants and impurities such as water. For example, water reacts with isocyanate to form gaseous carbon dioxide, so controlling the concentration of water can affect the concentration of carbon dioxide bubbles that form pores in the polymer matrix. The isocyanate reaction with exogenous water also reduces the isocyanate available for reaction with the chain extender, thus reducing the stoichiometric ratio as well as the level of crosslinking (if there are excess isocyanate groups) and the resulting polymer molecular weight. Change.

The polyurethane polymer material is preferably formed from a prepolymer reaction product of toluene diisocyanate with polytetramethylene ether glycol and an aromatic diamine. Most preferably, the aromatic diamine is 4,4'-methylene-bis-o-chloroaniline or 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline). Preferably, the range of unreacted prepolymer% NCO is 8.75 to 9.05. A specific example of a suitable prepolymer in this unreacted NCO range is Adiprene® prepolymer LF750D from Chemtura. In addition, LF750D represents a low free isocyanate prepolymer with less than 0.1% by weight of free 2,4 and 2,6 TDI monomers each and having a more consistent prepolymer molecular weight distribution than conventional prepolymers. . This “low free” prepolymer, along with improved prepolymer molecular weight consistency and low free isocyanate monomer, promotes a more regular polymer structure and contributes to improved polishing pad consistency. In addition to controlling the weight percent unreacted NCO, the curing agent and prepolymer reaction product generally provides a stoichiometric ratio of OH or NH ₂ to unreacted NCO of 80-97%, preferably 80-90%. has most preferably has a stoichiometric ratio from 83 to 87% of the OH or NH ₂ to unreacted NCO. This stoichiometric ratio can be achieved directly by providing a stoichiometric level of the feedstock, or by reacting a portion of the NCO with water intentionally or by exposure to exogenous moisture. It can also be achieved indirectly.

If the polishing pad is a polyurethane material, the finished polishing pad preferably has a density of 0.4 to 0.8 g / cm ³ . Most preferably, the finished polyurethane polishing pad has a density of 0.5 to 0.75 g / cm ³ . The nominal density of 20 μm pores or hollow polymer particles (before casting) of 3.25 to 4.25% by weight, preferably 3.25 to 3.6% by weight, based on the total pad formulation, is the desired density. Can be produced with excellent polishing results. In particular, the hollow polymer particles provide a random pore distribution in the polymer matrix. In particular, the polishing pad has a closed cell structure, and the polymer matrix forms a continuous network surrounding its closed cell structure. Despite this high porosity, polishing pads generally have a Shore D hardness of 44-54. For purposes of this specification, the Shore D test is conditioned by placing the pad sample in 50% relative humidity at 25 ° C. for 5 days prior to testing and repeating the hardness test using the method outlined in ASTM D2240. Including improving accuracy.

  The hollow polymer particles have a weight average diameter of 2 to 50 μm. For the purposes of this specification, the weight average diameter represents the diameter of the hollow polymer particles prior to casting, and the particles can be spherical or non-spherical. Most preferably, the hollow polymer particles are spherical. Preferably, the hollow polymer particles have a weight average diameter of 2 to 40 μm. Most preferably, the hollow polymer particles have a weight average diameter of 10 to 30 μm. These hollow polymer particles generally have an average density of 60 grams per liter. For the purposes of this specification, the average density of hollow polymer particles represents the close-packed uncollapsed density of hollow particles within a 1 liter volume. Hollow particles having an average diameter of 35-50 μm generally have a lower density, on average 42 grams per liter, due to fewer pores and fewer wall materials. Different sizes and types of hollow particles can be added with equal pore volumes by taking the mass of one size of hollow polymer particles and dividing by their density to determine the pore volume. Then, by multiplying this volume by the density of other pores and determining the mass of the size and type of hollow polymer particles, an equal amount of pore volume can be obtained. For example, a formulation having 3% by weight of 20 μm hollow polymer particles at a density of 60 grams per liter has 2.1% by weight of 42 μm hollow polymer particles at a density of 40 grams per liter, as shown by the following formula: Would be equal to the formulation.

When forming the polishing pad of the present invention, the density _a is equal to the average density of 60 g / l, the density _b is an average density of 5 g / l to 500 g / l, and the weight% _a is 3.25-4. .25% by weight. Preferably, density _b is an average density of 10 g / l to 150 g / l and weight% _a is 3.25 to 3.6% by weight.

The nominal range of the weight average diameter of the expanded hollow polymer particles is 15 to 90 μm. Furthermore, the combination of high porosity and small pore size can have special advantages in reducing the defect rate. However, if the porosity level becomes too high, the polishing pad loses mechanical integrity and strength. For example, adding hollow polymer particles having a weight average diameter of 2 to 50 μm constituting 30 to 60% by volume of the polishing layer promotes a reduction in the defect rate. Furthermore, if the porosity is maintained at 35 to 55% by volume, specifically 35 to 50% by volume, an increase in the removal rate can be promoted. For the purposes of this specification, volume% porosity is: 1) after determining the weight of the polymer lost from 1 cm ^{3 of} the formulation by subtracting the measured density of the formulation from the nominal density of the polymer without porosity 2) Determined by dividing the mass of the “lost” polymer by the nominal density of the polymer without pores to determine the volume of polymer lost from 1 cm ^{3 of} the formulation and multiplying by 100 to convert to a pore volume% value It represents the volume% of pores to be made. Alternatively, the volume% or volume% porosity of the pores in the formulation 1) subtract the mass of the hollow polymer particles in 100 g of the formulation from 100 g to determine the mass of the polymer matrix in 100 g of the formulation 2 ) Dividing the mass of the polymer matrix by the nominal density of the polymer to determine the volume of polymer in 100 g of the formulation, and 3) dividing the mass of hollow polymer particles in 100 g of the formulation by the nominal hollow polymer particle density, After determining the volume of hollow polymer particles in 1 cm ³ and 4) adding the volume of polymer in 100 g of formulation to the volume of hollow particles or pores in 100 g of formulation to determine the volume of 100 g of formulation, 5 ) Determined by dividing the volume of hollow particles or pores in 100 grams of formulation by the total volume of 100 grams of formulation and multiplying by 100 to yield the volume percent or porosity of the pores in the formulation. Rukoto can also. These two methods give similar values for volume% porosity or porosity, but the second method is that the parameters during processing, such as the exotherm of the reaction, give the hollow polymer particles or microspheres their nominal “expansion volume”. The volume% porosity or porosity value is lower than that of the first method, which may cause the expansion to exceed. For certain pores or porosity levels, pore size reduction tends to increase the polishing rate, thus controlling heat generation during casting to prevent further expansion of already expanded hollow polymer particles or microspheres. is important. For example, casting at room temperature, limiting cake height, reducing prepolymer temperature, reducing curing agent amine temperature, reducing NCO, and limiting free TDI monomer all reduce the exotherm caused by the reacting isocyanate. Contribute to that.

  As with most conventional porous polishing pads, polishing pad conditioning, such as diamond disk conditioning, acts to increase removal rate and improve wafer scale non-uniformity. Conditioning can work periodically, for example 30 seconds after each wafer processing, or continuously, but continuous conditioning provides the advantage of establishing steady state polishing conditions for improved removal rate control. . Conditioning generally increases the removal rate of the polishing pad and generally prevents a decrease in removal rate associated with polishing pad surface wear. In particular, abrasive conditioning forms a rough surface that can trap fumed silica particles during polishing. 1-3 show that silica particles can accumulate in the roughened surface adjacent to the pores of the polishing pad. This accumulation of silica particles in the polishing pad appears to increase the efficiency of the polishing pad by contributing to a high removal rate. In addition to conditioning, grooves and perforations can provide additional benefits to slurry dispersion, polishing non-uniformity, polishing litter removal and substrate removal rates.

  Various amounts of isocyanate as a urethane prepolymer and 4,4′-methylene-bis-o-chloroaniline [MBCA], in the examples of the present invention, at 49 ° C. for the prepolymer and for MBCA A polymer pad material was prepared by mixing at 115 ° C (comparative examples included 43-63 ° C for the prepolymer). In particular, certain types of toluene diisocyanate [TDI], with polytetramethylene ether glycol [PTMEG] prepolymer, imparted various properties to the polishing pad. This urethane / polyfunctional amine mixture was mixed with hollow polymer microspheres (EXPANCEL® 551DE20d60 or 551DE40d42 from AkzoNobel) before or after mixing the prepolymer with the chain extender. After mixing the hollow polymer microspheres with the prepolymer at 60 rpm before adding the polyfunctional amine, the mixture was mixed at 4500 rpm or the hollow polymer microspheres were added to the urethane / polyfunctional amine mixture at 3600 rpm in the mixing head. . The microspheres had a weight average diameter of 15-50 μm in the range of 5-200 μm. The final mixture was transferred to a mold and allowed to gel for about 15 minutes.

  The mold was then placed in a curing oven and cured with the following cycle. Increase from ambient temperature to the set temperature of 104 ° C over 30 minutes, hold at 104 ° C for 15 hours and 30 minutes, and reduce the set temperature to 21 ° C for 2 hours. Comparative Examples F-K used a shorter cure cycle of about 8 hours at 100 ° C. The molded article was then “skived” into a thin sheet at room temperature and the macrochannels or grooves were machined into the surface. Skiving at higher temperatures can improve surface roughness and sheet thickness uniformity. As shown in the table, samples 1 and 2 represent the polishing pad of the present invention, and samples A to Z represent comparative examples.

  An example polishing pad is obtained by polishing a TEOS sheet wafer on an Applied Materials Mirra® polisher using a platen rotation speed of 93 rpm, a wafer carrier head rotation speed of 87 rpm and a downforce of 5 psi. Tested. The polishing slurry was ILD3225 used as a 1: 1 mixture with DI water and was fed to the polishing pad surface at a rate of 150 ml / min. The polishing pad was diamond conditioned by in situ conditioning using a Diagrid® AD3BG150855 conditioning disk. A TEOS sheet wafer was polished for 30 or 60 seconds, and each test using the example pad also included a wafer polished with an IC1010 pad as a baseline. The 30 second polishing rate for IC1010 was focused on the maximum because it had the greatest effect over standard polishing pads on reducing polishing time. The polishing results are shown in Table 2 below.

  These data indicate that the added amount of 3.36 wt% hollow polymer microspheres provided an unexpected increase in removal rate. In particular, Samples 1 and 2 showed excellent removal rates at 30 and 60 seconds. The removal rate of Samples 1 and 2 at 30 seconds indicates that the polishing pad has a high removal rate at a relatively early part of the shortened polishing process that supports higher throughput polishing. Comparative examples of 3.01 (2.94 for the same prepolymer) or 3.66 wt% or higher resulted in a lower 30 second removal rate and a lower overall removal rate. In addition, FIGS. 1-3 show that the polishing pad surface is apparent to confine fumed silica in a location that is advantageous for polishing. It is clear that this affinity for fumed silica contributes to enhanced polishing performance.

Table 3 shows that hollow polymer microspheres achieve a microsphere loading level of over 1 million per cm ^{3 of} pad formulation.

  Table 4 below shows the prepolymer% NCO and the mechanical strength properties of MBCA cured elastomers made from the prepolymer used in the example formulations and without fillers or pores according to ASTM D412 method. Compare with the test used.

  The tensile properties shown are defined in ASTM D1566-08A. In addition, Table 4 shows the nominal density of MBCA cured prepolymer as reported by the prepolymer manufacturer.

  Table 4 shows that in addition to the filler concentration, it is clear that the mechanical properties of the polishing pad affect the polishing performance. Specifically, the polymer of Comparative Example R using LF600D is clearly insufficiently rigid, as clearly shown by its 100% modularity, for high removal rates in the case of fumed silica polishing. It is apparent that the polymers of Comparative Examples FK made using Royalcast® 2505 quasi-prepolymer are too stiff for high removal rates in fumed silica polishing. The polyurethane material molded from Royalcast 2505 was very brittle and broke before reaching 100% elongation.

  In short, the polishing pad is effective for polishing copper, insulators, barriers and tungsten wafers. In particular, the polishing pad is useful for ILD polishing, particularly for ILD polishing applications using fumed silica. The polishing pad has a steep increase to efficient polishing that provides a high removal rate in 30 seconds. The removal rate at 30 seconds and 60 seconds of the polishing pad of the present invention can exceed the removal rate at 30 seconds and 60 seconds of the IC1000 polishing pad. This rapid polishing response of the pad of the present invention promotes high wafer throughput as compared to conventional porous polishing pads.

Claims (10)

A polishing pad suitable for polishing a patterned semiconductor substrate comprising at least one of copper, insulator, barrier and tungsten, the polishing pad comprising a polymer matrix and hollow polymer particles in the polymer matrix. The polymer matrix is a polyurethane reaction product in which the stoichiometric ratio of NH _{2 to} NCO is 80-97% in the curing agent and isocyanate-terminated polytetramethylene ether glycol, and the isocyanate-terminated polytetramethylene ether glycol Having an unreacted NCO range of 8.75 to 9.05% by weight, the curing agent comprising a curing agent amine that cures the isocyanate-terminated polytetramethylene ether glycol to form the polymer matrix, and the hollow Polymer particles , As follows as a weight% _b and density _b of the average diameter and components forming the abrasive pad of 2~50μm

(Where
The density _a is equal to the average density of 60 g / l,
Density _b is an average density of 5 g / l to 500 g / l,
(% By weight _a is 3.25 to 4.25% by weight)
Wherein the polishing pad has a porosity of 30-60% by volume, and the closed cell structure in the polymer matrix forms a continuous network surrounding the closed cell structure.   The polishing pad of claim 1, wherein the continuous network forms a roughened surface that is conditioned with abrasive grains, the roughened surface being able to trap fumed silica particles during polishing.   The polishing pad of claim 1 having a Shore D hardness of 44-54.   The polishing pad according to claim 1, which has a porosity of 35 to 55% by volume.   The polishing pad according to claim 1, wherein the hollow polymer particles have an average diameter of 10 to 30 μm. A polishing pad suitable for polishing a patterned semiconductor substrate comprising at least one of copper, an insulator, a barrier and tungsten, comprising a polymer matrix and hollow polymer particles in the polymer matrix, the polymer The matrix is a polyurethane reaction product in which the stoichiometric ratio of NH _{2 to} NCO is 80-90% in the curing agent and isocyanate-terminated polytetramethylene ether glycol, and the isocyanate-terminated polytetramethylene ether glycol is 8. The hollow polymer particles having an unreacted NCO range of 75 to 9.05% by weight, the curing agent comprising a curing agent amine that cures the isocyanate-terminated polytetramethylene ether glycol to form the polymer matrix; 2-50 μm As it follows as a weight% _b and density _b of the average diameter and components forming the abrasive pad

(Where
The density _a is equal to the average density of 60 g / l,
The density _b is an average density of 10 g / l to 300 g / l,
(% By weight _a is 3.25 to 3.6% by weight)
Wherein the polishing pad has a porosity of 35-55% by volume, and the closed cell structure in the polymer matrix forms a continuous network surrounding the closed cell structure.   The polishing pad of claim 6, wherein the continuous network forms a roughened surface that is conditioned with abrasive grains, and the roughened surface can confine fumed silica particles during polishing.   The polishing pad of claim 6 having a Shore D hardness of 44 to 54.   The polishing pad according to claim 6, which has a porosity of 35 to 50% by volume.   The polishing pad according to claim 6, wherein the hollow polymer particles have an average diameter of 10 to 30 μm.