Chemical mechanical polishing composition for silicon-based material, and method

Abstract

A chemical mechanical polishing composition for a silicon-based material and a chemical mechanical polishing method. The composition comprises an abrasive material, a first polymer, and a second polymer. A portion of or all of the abrasive material is colloidal silica abrasive particles. The polishing composition can improve the polishing effect of a silicon-containing substrate. The product obtained after polishing has less haze, low light spot defects, fewer scratches, and lower roughness.

Description

Chemical mechanical polishing composition and method for silicon-based materials Technical Field

[0001] The present invention belongs to the field of chemical technology, and in particular relates to a chemical mechanical polishing composition for silicon-based materials and a chemical mechanical polishing method. Background Art

[0002] Chemical Mechanical Polishing (CMP) is a common process for achieving global planarization in integrated circuit manufacturing and other fields. This process is primarily used to create a smooth surface that is both flat and free of scratches and impurities. This process polishes various target substrates through a combination of chemical and mechanical forces, with chemical mechanical polishing (CMP) compositions playing a crucial role in this process. These compositions are typically aqueous solutions containing a uniform dispersion of various chemical additives and abrasive particles. CMP compositions are also known as polishing slurries, polishing solutions, or polishing compositions.

[0003] Semiconductor materials, primarily silicon, have become the most important foundational materials for the electronic information industry, occupying a crucial position in daily life and industrial applications. Over 95% of semiconductor devices worldwide are made of silicon, as are 85% of integrated circuits. Currently, integrated circuit technology has entered the nanoelectronics era, placing increasingly stringent demands on the surface finish quality of silicon single crystal wafers. Traditional polishing solutions are no longer sufficient for polishing silicon single crystal wafers. Silicon wafers used in electronic devices are obtained from single crystal silicon ingots using the Czochralski method. The ingots are then sliced ​​into thin wafers using a diamond saw. After rough polishing (also known as lapping), the silicon wafers are finely polished using a CMP composition to achieve the desired thickness and flatness. Wafer polishing using a CMPT composition typically involves a primary polish, an optional secondary polish, and a final polish.

[0004] The CMP process works as follows: a rotating silicon wafer, under pressure, moves relative to a rotating polishing pad. A smooth, flat surface is achieved through the combined mechanical abrasive action of the abrasive in the polishing slurry and the chemical reactions of various chemicals in the slurry. A traditional silicon wafer CMP system consists of three components: a rotating wafer clamping device, a worktable supporting the polishing pad, and a polishing slurry (slurry) supply system. Chemical reactions play a crucial role in the CMP process, with the polishing slurry being particularly crucial. Therefore, improving polishing slurries has been a constant research and development priority in the industry. Summary of the Invention

[0005] One object of the present invention is to overcome the aforementioned problems existing in the prior art. Preferably, one embodiment of the present invention provides a chemical mechanical polishing (CMP) composition suitable for final polishing of silicon-containing substrates, such as silicon wafers. After this secondary polishing, the treated silicon-containing substrate exhibits a high surface smoothness and flatness, thereby obtaining a final polished product. One object of the present invention is to overcome the problems of the prior art. In particular, the present invention provides a novel CMP composition suitable for final polishing of silicon-containing substrates (e.g., silicon wafers), which, on the one hand, exhibits a high material removal rate, and, on the other hand, results in fewer light point defects, lower haze, and a scratch-free product.

[0006] Preferably, an embodiment of the present invention provides a chemical mechanical polishing composition comprising an abrasive, a first polymer and a second polymer, wherein the dispersion degrees of the first polymer and the second polymer are both at most 2.3.

[0007] Preferably, the colloidal silica abrasive particles in the composition have a zeta potential of at least -3 mV at a pH of 9 to 12.

[0008] Preferably, the silica abrasive particles have a particle size distribution factor of at most 1.8, preferably at most 1.3, more preferably at most 1.0, more preferably at most 0.9, and most preferably at most 0.8, wherein the particle size distribution factor is calculated by the formula (D90-D10) / D50.

[0009] Preferably, the steepness coefficient of the silica abrasive is at least 34, preferably at least 48, more preferably at least 56, further preferably at least 67, and most preferably at least 74, and the steepness coefficient is calculated by the formula (D30 / D70)*100.

[0010] Preferably, the colloidal silica abrasive particles have a slope coefficient of at most 17, further preferably at most 15, more preferably at most 14, more preferably at most 13, more preferably at most 12, more preferably at most 11, and most preferably at most 10. Preferably, the glass transition temperature of the first polymer and the second polymer is lower than 160°C, preferably lower than 150°C, more preferably lower than 148°C.

[0011] Preferably, the dispersity of the second polymer is at most 2.3.

[0012] Preferably, the first polymer is hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, methyl cellulose, ethyl cellulose, propyl cellulose, cellulose acetate, a co-formed product thereof, or a combination thereof; preferably hydroxymethyl cellulose, hydroxyethyl cellulose, or hydroxypropyl cellulose, or a combination thereof.

[0013] Preferably, the second polymer is polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyacryloylmorpholine, or a combination thereof.

[0014] Preferably, the surfactant is selected from at least one of polyethylene glycol, polypropylene glycol, poly(ethylene oxide)-b-poly(propylene oxide), polyoxyethylene-polyoxypropylene copolymer, polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene hexyl ether, polyoxyethylene-polyoxyethylene alkylamine; poly((ethylene oxide)-b-(propylene oxide)-b(ethylene oxide)) triblock copolymer or a combination thereof.

[0015] Another object of an embodiment of the present invention is to provide a polishing method for a silicon-containing substrate, wherein the method is implemented using the above composition, and the composition is used in a final polishing step.

[0016] The CMP composition provided by the present invention can improve the polishing effect of silicon-containing substrates. The polished product has less haze (a fuzzy structure formed on the surface of the silicon wafer after polishing, which is proportional to the surface roughness), low light point defects (LPD, which refers to the number of residual abrasive particles after polishing and CMP cleaning of the silicon wafer. Residual abrasive particles have a negative effect and can cause defects in further processing of the silicon wafer), fewer scratches, and a lower roughness Ra. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a DSC graph of HEC in a composition provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The chemical mechanical polishing composition of the present invention comprises an abrasive, a first polymer, and a second polymer surfactant, wherein the abrasive is partially or entirely colloidal silica abrasive particles, and the first polymer has a dispersity of at most 2.3, wherein the dispersity is the ratio of the weight average molecular weight to the number average molecular weight of the polymer.

[0020] CMP compositions typically comprise an abrasive dispersed in an aqueous carrier. During the polishing process, the abrasive is used to remove excess material from the substrate surface, thereby achieving a flat, smooth surface. Preferably, the abrasive herein comprises at least 98 wt% silicon dioxide, with the remainder being metal oxides. In particularly preferred embodiments, the abrasive comprises entirely silicon dioxide particles, also referred to as abrasive grains.

[0021] Preferably, the silica particles can be silica prepared by pyrogenic methods (fumed silica), colloidal silica, or a mixture thereof. Colloidal silica refers to particles prepared by a wet process, while fumed silica refers to silica prepared by pyrogenic methods or flame hydrolysis. Colloidal silica can be obtained by wet processes such as precipitation (precipitated silica), polycondensation, or similar methods.

[0022] During use, the CMP composition of the present invention may contain at least 0.0005 wt% (weight percent) of abrasive, preferably at least 0.005 wt%, more preferably at least 0.01 wt%, even more preferably at least 0.01 wt% to 0.03 wt%, and even more preferably at least 0.05 wt% of abrasive, which may be entirely colloidal silica. In practice, if the weight percent of abrasive particles is too low, the material removal rate during the CMP process may be reduced. If the weight percent of abrasive particles is too high, the particles may form undesirable aggregates, which may cause defects such as scratches on the substrate surface during the CMP process. Therefore, during use, the composition preferably contains at most 10 wt% of abrasive (which may be entirely colloidal silica), more preferably at most 5 wt%, even more preferably at most 2 wt%, even more preferably at most 1 wt%, and even more preferably at most 0.8 wt% of abrasive. In a preferred embodiment, the composition comprises 0.0005 wt % to 10 wt %, more preferably 0.005 wt % to 5 wt %, more preferably 0.01 wt % to 5 wt %, more preferably 0.03 wt % to 1 wt %, and most preferably 0.05 wt % to 0.8 wt % of colloidal silica abrasive particles.

[0023] The average particle size of the abrasive affects the material removal rate from the substrate surface and is typically expressed as a diameter or diameter-related data. The average particle size can be obtained by dynamic light scattering measurements known to those skilled in the art (e.g., using a Malvern Mastersizer S from Malvern Instruments). The graph obtained from such measurements provides the cumulative volume percentage of particles of a certain size. The D50 average particle size corresponds to the value below which 50% of the particles have a diameter smaller than this value, also referred to as the median of the average particle size, or median diameter. In practical applications, a D50 that is too small can result in reduced material removal rates. Preferably, the colloidal silica abrasive has a D50 of at least 5 nm, more preferably at least 9 nm, more preferably at least 13 nm, more preferably at least 17 nm, and most preferably at least 20 nm, as characterized by dynamic light scattering measurements. On the other hand, if the D50 is too large, undesirable haze levels and light point defects (LPDs) may appear on the substrate surface during the CMP process. Preferably, the D50 of the colloidal silica abrasive particles, as characterized by dynamic light scattering measurements, is at most 150 nm, more preferably at most 125 nm, more preferably at most 100 nm, more preferably at most 90 nm, and most preferably at most 80 nm. In a specific embodiment, the D50 of the colloidal silica abrasive particles, as characterized by dynamic light scattering measurements, is in the range of 5 nm to 150 nm, preferably 9 nm to 125 nm, further preferably 13 nm to 100 nm, more preferably 17 nm to 90 nm, and most preferably 20 nm to 80 nm.

[0024] D10 refers to the value corresponding to the size below which 10% of the total particles are smaller. In embodiments of the present invention, the colloidal silica abrasive particles have a D10 of at least 1 nm, more preferably at least 3 nm, more preferably at least 6 nm, more preferably at least 8 nm, and most preferably at least 10 nm, as characterized by dynamic light scattering measurements. Abrasive particles with a smaller D10 can increase the particle packing density (reduce void volume) on the substrate surface during the CMP process, which helps improve material removal rates. Therefore, the colloidal silica abrasive particles have a D10 of at most 70 nm, preferably at most 60 nm, further preferably at most 50 nm, more preferably at most 40 nm, and most preferably at most 30 nm, as characterized by dynamic light scattering measurements. In preferred embodiments, the colloidal silica abrasive particles have a D10 of 1 nm to 70 nm, more preferably 3 nm to 60 nm, more preferably 6 nm to 50 nm, more preferably 8 nm to 40 nm, and most preferably 10 nm to 30 nm, as characterized by dynamic light scattering measurements.

[0025] Preferably, D90 refers to the value corresponding to the size that is smaller than 90% of the particles as a whole. A higher D90 of the abrasive can improve the material removal rate during the CMP process. Preferably, the colloidal silica abrasive has a D90 of at least 20 nm, preferably at least 30 nm, more preferably at least 40 nm, more preferably at least 50 nm, and most preferably at least 60 nm, as characterized by dynamic light scattering measurements. However, if the D90 of the abrasive is too high, more undesirable defects such as undesirable high haze and light point defects will appear during the CMP process. Therefore, in an embodiment of the present invention, the colloidal silica abrasive has a D90 of at most 250 nm, preferably at most 200 nm, further preferably at most 180 nm, more preferably at most 160 nm, and most preferably at most 150 nm, as characterized by dynamic light scattering measurements. In a preferred embodiment, the colloidal silica abrasive particles have a D90 of 20 nm to 250 nm, preferably 30 nm to 200 nm, further preferably 40 nm to 180 nm, more preferably 50 nm to 160 nm, and most preferably 60 nm to 150 nm, as characterized by dynamic light scattering measurements.

[0026] The width of the particle size distribution can be described by a particle size distribution factor, with a wide particle size distribution indicating a lower uniformity of the particle size distribution. The particle size distribution factor used in this application refers to the value obtained by the formula (D90-D10) / D50. A wide particle size distribution corresponds to a large particle size distribution factor; while a narrow particle size distribution corresponds to a small particle size distribution factor. D90, D10 and D50 can be obtained by dynamic light scattering as described above. Experiments have shown that an excessively large particle size distribution factor can lead to undesirable high haze levels, light point defects and scratches on the substrate surface during the CMP process. A small particle size distribution factor corresponds to less particle aggregation. Preferably, the colloidal silica abrasive has a particle size distribution factor of at most 1.8, preferably at most 1.7, more preferably at most 1.6, more preferably at most 1.5, more preferably at most 1.4, more preferably at most 1.3, more preferably at most 1.2, and most preferably at most 1.1.

[0027] In a preferred embodiment of the present application, the abrasive particles have a relatively large steepness coefficient. The steepness coefficient used herein refers to the value obtained by the formula (D30 / D70)*100. D30 and D70 can be obtained by dynamic light scattering as described above. The value corresponding to D30 indicates that 30% of the particles as a whole have a size smaller than this value. D70 indicates that 70% of the particles as a whole have a size smaller than D70. A wide particle size distribution provides a small steepness coefficient, while a narrow particle size distribution provides a large steepness coefficient. The inventors have found that abrasive particles with a large steepness coefficient result in fewer defects, lower haze levels, and fewer light point defects in the substrate surface during the CMP process. Preferably, the colloidal silica abrasive particles have a steepness coefficient of at least 61, preferably at least 62, more preferably at least 63, further preferably at least 64, further preferably at least 65, and most preferably at least 66. However, if the steepness coefficient is too large, the material removal rate during the CMP process will be reduced. Therefore, in the embodiments of the present invention, the colloidal silica abrasive grains have a steepness coefficient of at most 98, preferably at most 97, more preferably at most 96, and most preferably at most 95.

[0028] Preferably, the colloidal silica abrasive particles have a D30 of at least 4 nm, preferably 10 nm, more preferably at least 15 nm, more preferably at least 20, most preferably at least 25 nm, and most preferably 30 nm, as characterized by dynamic light scattering measurements. Preferably, the colloidal silica abrasive particles have a D30 of at most 353 nm, preferably at most 250 nm, more preferably at most 168 nm, more preferably at most 130 nm, further preferably at most 103 nm, and most preferably at most 90 nm, as characterized by dynamic light scattering measurements. Further preferably, the colloidal silica abrasive particles have a D30 of 4 nm to 353 nm, preferably 15 nm to 168 nm, further preferably 25 nm to 90 nm, as characterized by dynamic light scattering measurements.

[0029] Preferably, the colloidal silica abrasive particles have a D70 of at least 16 nm, more preferably at least 30 nm, more preferably at least 43 nm, further preferably at least 45 nm, most preferably at least 50 nm, and most preferably at least 62 nm, as characterized by dynamic light scattering measurements. Preferably, the colloidal silica abrasive particles have a D70 of at most 421 nm, preferably at most 300 nm, more preferably at most 218 nm, further preferably at most 150 nm, further preferably at most 137 nm, and most preferably at most 107 nm, as characterized by dynamic light scattering measurements. In another aspect, the abrasive particles have a D70 of from 16 nm to 421 nm, preferably from 30 nm to 218 nm, and most preferably from 45 nm to 107 nm, as characterized by dynamic light scattering measurements.

[0030] Preferably, the abrasive particles should have a small slope coefficient. As used herein, the term slope coefficient refers to the absolute value of the ascending slope of the particle size distribution plot divided by the descending slope. In a particle size distribution plot, the x-axis represents volume, and the y-axis represents particle percentage. The term ascending slope refers to the slope of a tangent line (straight line) drawn from P_D01 to P_max. The term descending slope refers to the slope of a tangent line (straight line) drawn from P_max to P_D99. P_D01 refers to the point in the particle size distribution plot where the particle size is equal to D01. Similar to D50 described above, D01 indicates that 1% of the particles are smaller than D01. P_D99 refers to the point in the particle size distribution plot where the particle size is equal to D99. D99 indicates that 99% of the particles are smaller than D99. P_max refers to the absolute maximum of the particle size distribution plot, i.e., the point in the particle size distribution plot where the corresponding particle size has the highest volume percentage. A smaller slope coefficient may result in a wider distribution of smaller particles than larger particles, which can improve particle accumulation during polishing. A smaller slope coefficient generally results in fewer defects, fewer light point defects, and lower substrate surface haze levels. Preferably, the colloidal silica abrasive particles should have a slope coefficient of at most 17, and in preferred embodiments, have a slope coefficient of at most 15, more preferably at most 14, more preferably at most 13, more preferably at most 12, more preferably at most 11, and most preferably at most 10.

[0031] A smaller slope coefficient can be achieved by improving the dispersibility of the particles and reducing the aggregation and agglomeration of the particles. Specifically, a smaller slope coefficient can be obtained by mechanical methods or chemical methods. Mechanical methods include ultrasonic or grinding treatment to decompose aggregates and agglomerates, or centrifugation to remove large particles, aggregates and agglomerates; chemical methods include operations such as adding chemical additives, such as adding suitable dispersants. For example, the first polymer and the second polymer of the present invention can interact with the particles and act as dispersants in the composition. The first polymer and the second polymer according to the present invention can help prevent the aggregation and agglomeration of the particles, thereby being used to achieve the desired slope coefficient. Similarly, the above-mentioned mechanical and chemical methods are also applicable to improving the steepness coefficient and particle size distribution factor of the composition of the present application.

[0032] Preferably, the abrasive particles should have a negative charge. Charge refers to the zeta potential, which can be measured, for example, using a Mastersizer S (Malvern Instruments). As known to those skilled in the art, zeta potential refers to the electrical potential at the interface between a flowing fluid within a composition and a fixed layer of fluid attached to the surface of the abrasive particles dispersed in the composition. The zeta potential generally depends on the pH of the composition. The higher the absolute value of the zeta potential, the stronger the electrostatic repulsion between the particles and the greater the dispersion stability of the particles in the composition. Preferably, the colloidal silica abrasive particles in the composition have a zeta potential of at least -5 mV, more preferably at least -10 mV, more preferably at least -15 mV, at least -20 mV, and most preferably at least -25 mV. Preferably, the colloidal silica abrasive particles have a zeta potential of at most -70 mV, preferably at most -60 mV, more preferably at most -55 mV, more preferably at most -50 mV, and most preferably at most -45 mV at a pH of 9 to 11. Preferably, the colloidal silica abrasive particles in the CMP composition of the present application have a zeta potential of -5 mV to -70 mV, more preferably -10 mV to -60 mV, more preferably -15 to -55 mV, more preferably -20 mV to -50 mV, more preferably -25 mV to -45 mV at a pH of 9 to 11.

[0033] Preferably, the composition further comprises one or more chemical additives. The chemical additives can interact with the abrasive and / or with the substrate and / or with the polishing pad during the CMP process. The interactions can be based on hydrogen bonding, van der Waals forces, electrostatic forces, etc. The chemical additives can be any suitable component, for example, used as a removal rate accelerator, polishing rate inhibitor, surfactant, thickener, conditioning agent, complexing agent, chelating agent, preservative, dispersant, oxidant, film former, etch inhibitor, catalyst, terminating compound, dissolution inhibitor or a combination thereof.

[0034] Preferably, the composition further comprises an aqueous carrier in which the abrasive particles and chemical additives are suspended or dissolved. The aqueous carrier enables the abrasive particles and chemical additives to come into contact with the substrate and polishing pad during the CMP process. The aqueous carrier can be any suitable component for suspending the abrasive particles and chemical additives. The aqueous carrier can be water, ethers (such as dioxane or tetrahydrofuran), alcohols (such as methanol and ethanol), and combinations thereof. Preferably, the aqueous carrier comprises at least 50 wt % water, preferably at least 70 wt % water, more preferably at least 90 wt % water, more preferably at least 95 wt % water, more preferably at least 99 wt % water. Most preferably, the aqueous carrier is deionized water.

[0035] Preferably, when used, the CMP composition further comprises a pH adjuster. The pH adjuster helps to achieve an appropriate pH in the composition. The pH adjuster also acts as an etchant and is used to assist in polishing silicon-containing substrates. The pH adjuster can be an alkali or a salt thereof, specifically an organic base, an inorganic base, or a combination thereof. The organic base can be a quaternary ammonium hydroxide (such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH)), piperazine, pyrazine, guanidine (such as guanidine carbonate, guanidine hydrochloride, arginine, creatine), imidazole, triazole, methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, ethylenediamine, monoethanolamine, diethanolamine, aminoethylethanolamine, linear primary diamine (such as butane-1,4-diamine, pentane-1,5-diamine, hexane-1,6-diamine, heptane-1,7-diamine, octane-1,8-diamine) or a combination thereof. Inorganic bases include alkali metal hydroxides (e.g., potassium hydroxide, sodium hydroxide, lithium hydroxide), alkaline earth metal hydroxides (e.g., magnesium hydroxide, calcium hydroxide, beryllium hydroxide), alkali metal carbonates (e.g., potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, lithium bicarbonate), alkaline earth metal carbonates (e.g., magnesium carbonate, calcium carbonate, beryllium carbonate), alkali metal phosphates (e.g., tripotassium phosphate, trisodium phosphate, dipotassium phosphate, disodium phosphate), alkaline earth metal phosphates (e.g., magnesium phosphate, calcium phosphate, beryllium phosphate), ammonium carbonate, ammonium bicarbonate, ammonium hydroxide, ammonia, or combinations thereof. Preferably, the pH adjuster is an inorganic base. In particularly preferred embodiments, the pH adjuster is selected from alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, ammonium carbonate, ammonia, and combinations thereof. In particularly preferred embodiments, the pH adjuster is ammonia. Experiments have demonstrated that the pH adjuster of the present application can increase the material removal rate of silicon-containing substrates.

[0036] Preferably, when used, the composition of the present application comprises at least 0.0001 wt%, more preferably at least 0.0005 wt%, more preferably at least 0.001 wt%, more preferably at least 0.003 wt%, more preferably at least 0.005 wt% of a pH adjuster. Preferably, when used, the composition of the present application comprises at most 2 wt%, more preferably at most 1 wt%, more preferably at most 0.5 wt%, more preferably at most 0.15 wt%, more preferably at most 0.09 wt% of a pH adjuster. In a preferred embodiment, the composition comprises 0.0001 wt% to 2 wt%, preferably 0.0005 wt% to 1 wt%, more preferably 0.001 wt% to 0.5 wt%, more preferably 0.003 wt% to 0.15 wt%, more preferably 0.005 wt% to 0.09 wt% of a pH adjuster.

[0037] Optionally, the composition of the present invention further comprises a buffer, which may be a phosphate, sulfate, acetate, borate, ammonium salt, or a combination thereof. The buffer maintains the composition at a specific pH range, which influences the substrate removal rate during the polishing process. Alkaline pH values ​​can increase the material removal rate of the substrate during polishing. Therefore, during use, the composition preferably has a pH of 7.0 or greater, preferably 7.5 or greater, preferably 8.0 or greater, more preferably 8.5 or greater, and most preferably 9.0 or greater.

[0038] Preferably, the composition of the present application further comprises a first polymer. Preferably, the first polymer is a hydrophilic nonionic polymer. Preferably, the first polymer is a water-soluble polymer. As used herein, the term "water-soluble" refers to a polymer having a solubility of at least 0.1 mg / ml in water at 25°C. Preferably, the first polymer is readily soluble in water at 25°C. The first polymer may be a homopolymer, a copolymer, or a combination thereof. Preferably, the first polymer is a homopolymer. Preferably, the first polymer is a cellulosic compound. Examples of the first polymer are hydroxymethyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose (HEMC), ethyl hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, methyl cellulose, ethyl cellulose, propyl cellulose, cellulose acetate, co-formed products thereof, or combinations thereof. In particularly preferred embodiments, the first polymer is selected from hydroxymethyl cellulose, hydroxyethyl cellulose (HEC), and hydroxypropyl cellulose (HPC), and combinations thereof. The first polymer simultaneously functions as a wetting agent and a thickening agent.

[0039] Furthermore, the first polymer should have a narrow molecular weight distribution. A broad molecular weight distribution of a polymer can lead to undesirable defects on the substrate surface. The width of the distribution can be described by dispersity (D). Dispersity refers to the ratio of the weight-average molecular weight to the number-average molecular weight of a polymer. Dispersity can be measured, for example, using a commercially available gel permeation chromatography (Agilent 1260 series, Agilent Technologies). High dispersity is associated with a broad molecular weight distribution of the polymer, while low dispersity is associated with a narrow molecular weight distribution of the polymer. Preferably, the first polymer has a dispersity (D) of at most 2.30, more preferably at most 2.20, more preferably at most 2.10, more preferably at most 2.00, more preferably at most 1.90, and most preferably at most 1.85. Low dispersity can be achieved, for example, through synthesis or dialysis. Experimental studies have shown that the first polymer with low dispersity used in embodiments of the present invention can reduce the number of defects, such as scratches and nanoscratches, on the surface of silicon-containing substrates during polishing. Scratches are damaged areas on the wafer surface. Nanoscratches are relatively shallow and slightly visible in natural light, but typically cover the entire surface of the silicon wafer.

[0040] The first polymer should have a low glass transition temperature (Tg). The glass transition temperature is the temperature at which a material transitions from a hard, brittle state to a soft, deformable, or rubbery state. The glass transition temperature can be measured using differential scanning calorimetry (DSC), such as a TA Instruments DSC (Model: SDT Q600, USA). The glass transition can be observed as a step in the baseline, and the Tg can be obtained, for example, from half the step height, as known to those skilled in the art. The glass transition temperature of a polymer significantly influences its performance because it is related to the mobility of the polymer chains. The more immobile the polymer chains, the higher the Tg value. In particular, any structure that restricts rotational motion within the polymer chain will increase the Tg. Bulky, inflexible side groups increase the Tg of a material due to reduced mobility. Increased crosslinking also reduces the polymer's mobility, resulting in a decrease in free volume and an increase in the Tg. A lower Tg also corresponds to higher polymer flexibility and mobility. Preferably, the glass transition temperature of the first polymer is at most 160° C., more preferably at most 158° C., more preferably at most 156° C., more preferably at most 154° C., more preferably at most 152° C., more preferably at most 151° C., and most preferably at most 150° C. Experiments have shown that a first polymer with a low Tg results in a corresponding polymer having low haze, low LPD, low Ra, and fewer scratches and nanoscratches.

[0041] The inventors have also discovered that the ratio of the Tg of the first polymer to the slope coefficient of the colloidal silica particles can be used as a characteristic of the CMP composition. A high slope coefficient indicates a "tail" in the particle size distribution curve, which indicates the presence of large particles that may cause defects / scratches. Generally, larger particles are more likely to cause defects than smaller particles. The polymer in the CMP composition can bind to the particles and "cap" them, preventing them from causing scratches. A higher polymer mobility (corresponding to a lower Tg) allows for more effective binding to the particles and scratch prevention. The inventors have discovered that a higher ratio of the Tg of the first polymer to the slope coefficient of the colloidal abrasive particles indicates fewer defects. Preferably, the ratio of the Tg of the first polymer to the slope coefficient of the colloidal abrasive particles is at least 10, preferably at least 7, more preferably at least 15, more preferably at least 18, even more preferably at least 20, even more preferably at least 22, and most preferably at least 25.

[0042] Preferably, when used, the CMP composition comprises at least 0.0001 wt%, more preferably at least 0.0005 wt%, more preferably at least 0.001 wt%, more preferably at least 0.002 wt%, and more preferably at least 0.004 wt% of the first polymer. Preferably, when used, the composition comprises at most 2 wt%, more preferably at most 1 wt%, more preferably at most 0.5 wt%, more preferably at most 0.15 wt%, and more preferably at most 0.1 wt% of the first polymer. In a preferred embodiment, the composition comprises the first polymer in an amount of 0.0001 wt% to 2 wt%, more preferably 0.0005 wt% to 1 wt%, more preferably 0.001 wt% to 1 wt%, 0.5 wt%, more preferably 0.002 wt% to 0.15 wt%, and more preferably 0.004 wt% to 0.1 wt%.

[0043] The first polymer should have a high molecular weight (MW). As used herein, molecular weight refers to weight average molecular weight. Preferably, the molecular weight of the first polymer is at least 10,000 g / mol, more preferably at least 40,000 g / mol, more preferably at least 60,000 g / mol, more preferably at least 80,000 g / mol, and most preferably at least 100,000 g / mol. Preferably, the molecular weight of the first polymer is at most 5,000,000 g / mol, more preferably at most 1,000,000 g / mol, more preferably at most 900,000 g / mol, more preferably at most 800,000 g / mol, and most preferably at most 700,000 g / mol. Preferably, the molecular weight of the first polymer is 10,000 g / mol to 5,000,000 g / mol, more preferably 40,000 g / mol to 1,000,000 g / mol, more preferably 60,000 g / mol to 900,000 g / mol, more preferably 80,000 g / mol to 800,000 g / mol, more preferably 100,000 g / mol to 700,000 g / mol.

[0044] Preferably, the composition of the present application further comprises a second polymer, preferably, the second polymer is a nonionic polymer. Preferably, the second polymer is a water-soluble polymer. Preferably, the second polymer is readily soluble in water at 25°C. The second polymer may be a homopolymer, a copolymer, or a combination thereof. Preferably, the second polymer is a homopolymer. Preferably, the second polymer is a vinyl polymer. The second polymer may be polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), or polyacryloylmorpholine. The second polymer may be used to prevent the aggregation of abrasive particles, which may cause defects such as scratches on the surface of the substrate; at the same time, the second polymer may help reduce the swelling of the first polymer.

[0045] Preferably, the second polymer has a dispersion degree (D) of at most 2.30, more preferably at most 2.20, more preferably at most 2.10, more preferably at most 2.00, more preferably at most 1.90, and most preferably at most 1.85. Experiments have shown that the second polymer enables the polymer of the present application to have lower haze, lower light point defects, lower surface roughness, fewer scratches, and fewer nanoscratches.

[0046] The inventors have discovered that when both the first and second polymers have low dispersities, the composition can exhibit the following beneficial effects: low haze, low LPD, and reduced scratching. Preferably, the first and second polymers have a dispersity (D) of at most 2.30, more preferably at most 2.20, more preferably at most 2.10, more preferably at most 2.00, more preferably at most 1.90, and most preferably at most 1.85.

[0047] Preferably, the glass transition temperature of the second polymer is at most 160° C., more preferably at most 158° C., more preferably at most 156° C., more preferably at most 154° C., more preferably at most 152° C., more preferably at most 151° C., and most preferably at most 150° C. Experiments have shown that a second polymer with a low Tg results in a corresponding polymer having low haze, low LPD, low Ra, and fewer scratches and nanoscratches.

[0048] The inventors have discovered that when both the first polymer and the second polymer have low glass transition temperatures, the composition can exhibit lower haze, lower LPD, and reduced scratching. Preferably, the first polymer and the second polymer both have glass transition temperatures of at most 160°C, more preferably at most 158°C, more preferably at most 156°C, more preferably at most 154°C, more preferably at most 152°C, more preferably at most 151°C, and most preferably at most 150°C.

[0049] The inventors have discovered that the higher the ratio of the Tg of the second polymer to the slope coefficient of the colloidal abrasive particles, the fewer defects. Preferably, the ratio of the Tg of the second polymer to the slope coefficient of the colloidal abrasive particles is at least 5, preferably at least 7, more preferably at least 9, even more preferably at least 11, even more preferably at least 12, and most preferably at least 13.

[0050] The inventors have discovered that the higher the ratio of the Tg of the first and second polymers to the slope coefficient of the colloidal particles, the fewer defects; preferably, both the first and second polymers have high ratios. Preferably, the ratios of the first and second polymers are each at least 5, preferably at least 7, more preferably at least 9, even more preferably at least 11, even more preferably at least 12, and most preferably at least 13.

[0051] Preferably, when used, the CMP composition comprises at least 0.0001 wt%, more preferably at least 0.0003 wt%, more preferably at least 0.0005 wt%, more preferably at least 0.001 wt%, and more preferably at least 0.002 wt% of the second polymer. Preferably, when used, the composition comprises at most 2 wt%, more preferably at most 1 wt%, more preferably at most 0.5 wt%, more preferably at most 0.12 wt%, and more preferably at most 0.08 wt% of the second polymer. In a preferred embodiment, the composition contains from 0.0001 wt% to 2 wt%, more preferably from 0.0003 wt% to 1 wt%, more preferably from 0.0005 wt% to 1 wt%, more preferably from 0.001 wt% to 0.12 wt%, and more preferably from 0.002 wt% to 0.08 wt% of the second polymer.

[0052] Preferably, the second polymer should have a lower molecular weight (MW) than the first polymer. Preferably, the second polymer has a molecular weight of at least 1,000 g / mol, more preferably at least 2,000 g / mol, more preferably at least 3,000 g / mol, more preferably at least 4,000 g / mol, and most preferably at least 5,000 g / mol. Preferably, the molecular weight of the second polymer is at most 500,000 g / mol, more preferably at most 400,000 g / mol, more preferably at most 300,000 g / mol, more preferably at most 200,000 g / mol, and most preferably at most 100,000 g / mol. Preferably, the second polymer has a molecular weight of 1,000 to 500,000 g / mol, more preferably 2,000 to 400,000 g / mol, more preferably 3,000 to 300,000 g / mol, more preferably 4,000 to 200,000 g / mol, more preferably 5,000 to 100,000 g / mol.

[0053] Preferably, the composition of the present invention further comprises a chelating agent, which can help bind unwanted metal ions that may be formed during the CMP process and prevent metal ion contamination of the substrate surface. Suitable chelating agents include dicarboxylic acids, polycarboxylic acids, amino acids, aminocarboxylic acids, aminopolycarboxylic acids, phosphates, polyphosphates, aminophosphonic acids, phosphonocarboxylic acids, and combinations thereof. Dicarboxylic acids can specifically include oxalic acid, malonic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, aspartic acid, glutamic acid, and combinations thereof. Polycarboxylic acids can include citric acid, butanetetracarboxylic acid, and combinations thereof. The aminopolycarboxylic acid may be: ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylene glycoldiaminetetraacetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), diaminohydroxypropanetetraacetic acid (DTPA-OH), triethylenetetraaminehexaacetic acid (TTHA), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), bisaminophenoxyethanetetraacetic acid (BAPTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), nicotinamide, ethylenediaminebishydroxyphenylacetic acid (EDDHA) and combinations thereof. The aminophosphonic acid may specifically be: ethylenediaminetetra(methylenephosphonic acid) (EDTMP), aminotri(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP) and combinations thereof. In a preferred embodiment, the chelating agent is an aminopolycarboxylic acid. In a particularly preferred embodiment, the chelating agent is selected from EDTA, DTPA-OH, HEDTA, EGTA, DTPA, TTHA, DTPMP, EDTMP, and combinations thereof. Experiments have shown that the chelating agent used in the embodiments of the present invention can increase the material removal rate of the substrate during the polishing process.

[0054] Preferably, when used, the composition of the present invention comprises at least 0.5ppm, preferably at least 1ppm, more preferably at least 4ppm, more preferably at least 8ppm, and most preferably at least 10ppm of a chelating agent. Preferably, the composition comprises at most 1,000ppm, preferably at most 800ppm, more preferably at most 500ppm, more preferably at most 200ppm, and most preferably at most 100ppm of a chelating agent. Thus, the composition comprises from 0.5ppm to 1,000ppm, preferably from 1ppm to 800ppm, more preferably from 4ppm to 500ppm, more preferably from 8ppm to 200ppm, and most preferably from 10ppm to 100ppm of a chelating agent. As used herein, the term "ppm" refers to parts per million by mass.

[0055] Preferably, the composition comprises a surfactant, which can help enhance stability, improve humidity, control light point defects, and reduce surface roughness and haze. The surfactant can be an anionic surfactant or a nonionic surfactant. Preferably, the surfactant is a nonionic surfactant. Examples of surfactants are polyethylene glycol, polypropylene glycol, polyglycerol, polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxybutylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene fatty acid ester, polyoxyethylene glycerol ether fatty acid ester, polyoxyethylene dehydrated sorbitan fatty acid ester, polyoxyethylene polyoxypropylene copolymer, poly(ethylene oxide)-b-poly(propylene oxide), polyoxyethylene glycol, polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, Polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene dodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene alkenyl ether, polyoxyethylene dioxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearamide, polyoxyethylene oleamide, polyoxyethylene monolaurate, polyoxyethylene mono Stearate, polyoxyethylene distearate polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tetraoleate, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, acetylene glycol, polyoxyethylene-polyoxyethylene alkylamine; poly((ethylene oxide)-b-(propylene oxide)-b(ethylene oxide)) triblock copolymer or a combination thereof. Preferably, the surfactant is selected from at least one of polyethylene glycol, polypropylene glycol, poly(ethylene oxide)-b-poly(propylene oxide), polyoxyethylene-polyoxyethylene alkylamine, poly((ethylene oxide)-b-(propylene oxide)-b(ethylene oxide)) triblock copolymer, polyoxyethylene-polyoxypropylene copolymer, and polyoxyethylene alkyl ether (PEOLE-polyoxyethylene lauryl ether; or PEOHE-polyoxyethylene hexyl ether). Surfactants can effectively reduce haze levels and light point defects in silicon-containing substrates.

[0056] Preferably, the composition of the present application comprises at least 1 ppm, preferably at least 5 ppm, more preferably at least 10 ppm, more preferably at least 15 ppm, and most preferably at least 20 ppm of a surfactant. Preferably, the composition comprises at most 5,000 ppm, more preferably at most 3,000 ppm, more preferably at most 1,000 ppm, more preferably at most 800 ppm, and most preferably at most 600 ppm of a surfactant. Preferably, the composition comprises the surfactant in an amount of 1 ppm to 5,000 ppm, more preferably 5 ppm to 3,000 ppm, more preferably 10 ppm to 1,000 ppm, more preferably 15 ppm to 800 ppm, and most preferably 20 ppm to 600 ppm.

[0057] Preferably, the surfactant has a molecular weight of at least 100 g / mol, more preferably at least 400 g / mol, more preferably at least 600 g / mol, more preferably at least 900 g / mol, and most preferably at least 1,000 g / mol. Preferably, the surfactant has a molecular weight of at most 50,000 g / mol, more preferably at most 40,000 g / mol, more preferably at most 30,000 g / mol, more preferably at most 20,000 g / mol, and most preferably at most 15,000 g / mol. Preferably, the surfactant has a molecular weight of from 100 g / mol to 50,000 g / mol, more preferably from 400 g / mol to 40,000 g / mol, more preferably from 600 g / mol to 30,000 g / mol, more preferably from 900 g / mol to 20,000 g / mol, more preferably from 1,000 g / mol to 15,000 g / mol.

[0058] Preferably, the composition of the present application comprises a surfactant having a dispersity (D) of no greater than 2.3, preferably no greater than 2.20, more preferably no greater than 2.10, more preferably no greater than 2.00, more preferably no greater than 1.90, and most preferably no greater than 1.85. Surfactants having such a dispersity (D) can reduce the number of defects, such as scratches and nanoscratches, on the surface of silicon-containing substrates during CMP polishing, while also reducing haze, LPD, and surface roughness.

[0059] The inventors have discovered that when the first polymer, the second polymer, and the surfactant all have low dispersities, the composition can exhibit low haze, low LPD, reduced scratches, and reduced nanoscratches. Further preferably, the first polymer, the second polymer, and the surfactant all have a dispersity of at most 2.30, more preferably at most 2.20, more preferably at most 2.10, more preferably at most 2.00, more preferably at most 1.90, and most preferably at most 1.85.

[0060] The composition of the present application also preferably comprises an acid agent, which can be an organic acid or an inorganic acid. The acid agent can be present in the composition in any suitable form, such as acid, conjugate acid, salt (such as potassium salt, sodium salt, ammonium salt) or its combination. The example of an inorganic acid is hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, phosphoric acid and a combination thereof. Examples of organic acids are formic acid, acetic acid, propionic acid, butyric acid, valeric acid, methylbutyric acid, caproic acid, dimethylbutyric acid, ethylbutyric acid, methylvaleric acid, enanthic acid, methylhexanoic acid, caprylic acid, ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, malic acid, phthalic acid, tartaric acid, muconic acid, citric acid, lactic acid, diglycolic acid, furan carboxylic acid, suberic acid, azelaic acid, aspartic acid, tetrahydrofuranic acid, methoxyacetic acid, methoxyphenylacetic acid, sebacic acid, glutaconic acid, phenoxyacetic acid, methanesulfonic acid, methoxyphenylacetic acid, ethanesulfonic acid, sulfosuccinic acid, benzenesulfonic acid, toluenesulfonic acid, phenylphosphonic acid, hydroxyethyl diphosphonic acid and combinations thereof. Preferably, the acid agent is an inorganic acid. In particularly preferred embodiments, the acid agent is selected from nitric acid, hypophosphorous acid, phosphorous acid, phosphoric acid, sulfuric acid and combinations thereof. The acidic agent in the composition of the present application can adjust the pH value of the composition and increase the wettability of the polishing substrate surface.

[0061] Preferably, the composition comprises at least 0.5 ppm, preferably at least 1 ppm, more preferably at least 4 ppm, more preferably at least 8 ppm, and most preferably at least 10 ppm of the above-mentioned acidic agent. Preferably, the composition comprises at most 1,000 ppm, more preferably at most 800 ppm, more preferably at most 500 ppm, more preferably at most 200 ppm, and most preferably at most 100 ppm of the above-mentioned acidic agent. Preferably, the composition comprises from 0.5 ppm to 1,000 ppm, more preferably from 1 ppm to 800 ppm, more preferably from 4 ppm to 500 ppm, more preferably from 8 ppm to 200 ppm, and most preferably from 10 ppm to 100 ppm of the acidic agent.

[0062] Optionally, said composition also includes one or more preservatives. Preservative can be any suitable compound, which can prevent, suppress, reduce the growth of unwanted microorganisms, suppress its activity or eliminate unwanted microorganisms. The example of a suitable preservative is sodium hypochlorite, methylisothiazolinone, benzisothiazolinone, chloromethylisothiazolinone and a combination thereof. Preferably, in use, the composition comprises at least 0.1ppm by weight, more preferably at least 1ppm by weight, more preferably at least 1.5ppm, more preferably at least 2ppm, most preferably at least 2.5ppm of preservative. High concentrations of preservative can cause undesirable interactions to occur between the preservative and other components of the composition and the base material. Therefore, in use, the composition preferably comprises at most 100ppm by weight, more preferably at most 80ppm, more preferably at most 75ppm, more preferably at most 70ppm of preservative.

[0063] Another aspect of the present invention provides a method for chemically mechanically polishing a silicon-containing substrate, comprising the following steps: (a) providing the chemical mechanical polishing composition described above; (b) contacting the silicon-containing substrate with the chemical mechanical polishing composition and a polishing pad; (c) moving the polishing pad relative to the silicon-containing substrate with the chemical mechanical polishing composition disposed therebetween; and (d) removing at least a portion of the silicon-containing substrate. The method may optionally include other steps.

[0064] The abrasive particles of the present application and the aforementioned characteristics of the abrasive particles can be obtained by methods well known to those skilled in the art. In specific embodiments, the colloidal silica particles can be prepared by polycondensation, for example, by condensing Si(OH)4 to form spherical particles. Si(OH)4 can be obtained by hydrolysis of alkoxysilanes or acidification of aqueous silicate solutions. Colloidal silica abrasive particles can be prepared by precipitation from an acidic solution containing sodium silicate and sulfuric acid. Colloidal silica abrasive particles can also be purchased commercially from, for example, Bayer, DuPont, Fuso Chemical, Nalco, and Nissan Chemical. The particles are dispersed, for example, by stirring and used to formulate the composition.

[0065] The abrasives and chemical additives described above can be added to the aqueous carrier in any order and in appropriate amounts to achieve the desired concentration to prepare the composition. The abrasive particles and chemical additives can be mixed and stirred in the aqueous carrier. The pH can be adjusted to achieve and maintain the desired pH using the pH adjusters and pH buffers described above. The abrasive particles and chemical additives can be added before use or at any time during the CMP process (e.g., one month, one day, one hour, or one minute).

[0066] The above-described composition can be provided as a one-part system, a two-part system, or a multi-part system. For example, as a two-part system, the first part may include abrasive particles and one or more chemical additives, and the second part may include a pH adjuster and one or more chemical additives. The first and second parts can be combined at any time before or during the CMP process (e.g., one month, one day, one hour, or one minute), such as when using a polishing apparatus having multiple supply paths for the CMP composition.

[0067] The above-described composition can be provided as a concentrate and diluted with a suitable amount of water before use. The concentrations of the composition components can be any suitable concentration, for example, 2, 3, 10, 25, or 100 times the above-described point-of-use concentrations. For example, the concentrate can contain the abrasive and chemical additives at concentrations such that, upon dilution with a suitable amount of water, the abrasive and optional chemical additives are present in the composition at the above-described concentrations. If the composition is provided, for example, as a two-part system, one or both parts can be provided as a concentrate. The two parts can be provided at different concentrations, for example, the first part at a concentration of three times and the second part at a concentration of five times. The two parts can be diluted in any order before mixing.

[0068] The present invention also relates to the use of the above-mentioned composition of the present invention. Preferably, the composition of the present invention is used for chemical mechanical polishing of silicon-containing substrates. The composition can be used for surface polishing of silicon wafers, for example, for primary polishing, secondary polishing, final polishing and polishing in silicon wafer recycling. In a preferred embodiment, the composition according to the present invention is used for final polishing of silicon wafers. Preferably, the silicon can be undoped silicon or doped silicon, for example boron- or aluminum-doped silicon. The silicon can also be single crystal silicon or polycrystalline silicon. In a specific embodiment, the silicon can also include silicon oxide. As known to those skilled in the art, chemical mechanical polishing refers to: a substrate is arranged in contact with a polishing pad and a CMP composition located therebetween in a CMP device, and the polishing pad and substrate are moved relative to each other to remove a portion of the substrate, preferably, the substrate is undoped single crystal silicon.

[0069] The present application is described in detail below through specific embodiments.

[0070] Example 1 Preparation of Low Dispersity Polymers The dispersity of all three polymers can be controlled by the temperature, time and ratio of added molecules during the synthesis process, as is known to those skilled in the art.

[0071] Synthesis of Hydroxyethyl Cellulose (HEC):

[0072] 7.5 g of NaOH, 11 g of urea, and 81.5 g of distilled water were added to a beaker. The resulting solution was precooled to -12°C, followed by the addition of 200 g of cellulose and vigorous stirring at room temperature for 10 minutes. A mixture of anhydroglucose units (AGU) and chlorohydrin in a 1:6 molar ratio was added to the cellulose solution, stirred at room temperature for 1 hour, and heated to 50°C for 5 hours. The resulting crude polymer was neutralized with acetic acid, dialyzed, and freeze-dried. The resulting HEC polymer had a dispersity of 1.51.

[0073] Synthesis of polyvinylpyrrolidone (PVP) (preparation steps can refer to US 6,486,281 B1)

[0074] 120 g of vinyl pyrrolidone, 180 g of water, 6.6 g of ammonium sulfite (5.5% by weight based on the weight of vinyl pyrrolidone), and 0.96 g of tert-butyl hydroperoxide (0.8% by weight based on the weight of vinyl pyrrolidone) were added to 25 g of regenerated anion exchange resin and stirred at 50°C for 1 hour to disperse. The VP polymer (PVP) aqueous solution and the anion exchange resin were then separated by centrifugation. The resulting PVP dispersion had a value of 1.62.

[0075] In other embodiments, PVP may be synthesized by free radical polymerization using azobisisobutyronitrile (AIBN) as an initiator.

[0076] Synthesis of PEO-b-PPO

[0077] PEO-b-PPO was prepared by anionic polymerization using potassium tert-butoxide as initiator.

[0078] To synthesize a diblock copolymer with tert-butyl end groups on PPO, the PPO block was first synthesized by initiating and propagating propylene oxide using potassium tert-butoxide as an initiator at room temperature. 18-Crown-6 ether was added to the reaction at a 2:1 molar ratio of initiator to 18-crown-6 ether to reduce dispersibility and increase propylene oxide conversion. After 48 hours, the reaction was terminated with acidic methanol (37 w / w% hydrochloric acid:methanol ratio 1:10). The potassium and crown ether complexes were removed by filtration, solvent removal, and dissolution in fresh THF until a clear solution was obtained. The PEO block was propagated by reinitiating the PPO block with potassium naphthalene at 40°C. After 20 hours, the reaction was terminated with acidic methanol. After termination, the diblock copolymer was repeatedly dissolved in fresh solvent, filtered, and further purified by dialysis. The resulting polymer had a dispersity of 1.15.

[0079] Example 2 Preparation of composition

[0080] All compositions of the examples were prepared by adding the chemical additives and dissolving them in deionized water, then adding the colloidal silica abrasive and stirring until the colloidal silica abrasive particles were dispersed.

[0081] Example 3

[0082] Compositions A1-A3 and E1-E9 were evaluated for the presence of light defects, haze, surface roughness, and scratches on polished silicon wafers. All compositions contained 0.18 wt.% colloidal silica, 0.0015 wt.% ethylenediaminetetraacetic acid, 0.0004 wt.% nitric acid, 80 ppm HEC (MW 500,000 g / mol), 40 ppm PVP (MW 24,000 g / mol), 30 ppm PEO-b-PPO (MW 8,400 g / mol), and 30 ppm of the preservative KATHON™ LX 150 (Dow Chemical). The pH of all compositions was adjusted to 10.5 with ammonia. The dispersions of HEC, PVP, and PEO-b-PPO were measured before addition to the compositions using an Agilent 1260 Infinity II Size Exclusion Chromatography System (Agilent Technologies) and are listed in Table 1.

[0083] All compositions were used to polish silicon wafers, and then cleaned as described in the Examples. Light point defects on the wafers were measured to be at least 45 nm. Additionally, haze levels were measured under the same conditions as for light point defects. Table 1 lists light point defects and haze levels as a percentage relative to composition A2.

[0084] The polished and cleaned silicon wafer surfaces were inspected for scratches and microcracks. The presence of microcracks was considered positive if the wafer was covered with continuous nano- and microcracks as detected by the measured haze map. In addition, the number of non-continuous scratches that could be counted and were visible to the naked eye is listed in Table 1.

[0085] The surface roughness (Ra) of polished and cleaned silicon wafers was measured using a Park AFM instrument (Park Instruments) at two randomly selected measurement points within a 10 µm² area in the center of the wafer and 3 nm from the edge. Surface roughness (Ra) is the arithmetic mean of the absolute deviations of the profile height from the mean height. Table 5 lists the surface roughness (Ra) in Å as the average of the two measurement points near the center and edge.

[0086] Table 1

[0087]

[0088] As can be seen in Table 1, compositions A1-A3, containing all three polymers HEC, PVP, and PEO-b-PPO with higher dispersions, exhibited higher haze levels, higher light point defects, microcracks, a higher number of scratches, and higher surface roughness compared to compositions E1-E9. Examples E1-E3, containing HEC with higher dispersions and PVP and PEO-b-PPO with lower dispersions, and Examples E4-E6, containing HEC with lower dispersions and PVP and PEO-co-PPSO with higher dispersions, exhibited no microcracks, one scratch, significantly lower light point defects, significantly lower haze, and significantly lower surface roughness compared to compositions A1-A3. Compositions E7-E9, containing all three polymers HEC, PVP, and PEO-b-PPO, exhibited lower dispersions, no microcracks, no scratches, significantly lower light point defects, significantly lower haze, and significantly lower surface roughness compared to compositions A1-A3 and E1-E6. Example 4

[0089] The experimental conditions are similar to those of Example 3 (except that the polymer used is a different molecule, as shown in Table 2 below).

[0090] Table 2

[0091] abbreviation:

[0092] HPC-hydroxypropyl cellulose, HEMC-hydroxyethyl methyl cellulose, HPMC-hydroxypropyl methyl cellulose, EHEC-ethyl hydroxyethyl cellulose, PVA-polyvinyl alcohol, PVC-polyvinyl caprolactam, PACMO-polyacryloylmorpholine, PVSA-polyvinyl sulfonic acid; PEOLE-polyoxyethylene lauryl ether; PEOHE-polyoxyethylene hexyl ether; PEOAA-polyoxyethylene-polyoxyethylene alkylamine; PEO-b-PPO-b-PEO poly((ethylene oxide)-b-(propylene oxide)-b(ethylene oxide)) triblock copolymer.

[0093] As can be seen from Table 2, compared with compositions A4-A7, Examples E10-E13 containing a first polymer with lower dispersion, a second polymer and a surfactant showed no scratches, no nanoscratches, and significantly lower light point defects, significantly lower haze and significantly lower surface roughness.

[0094] Example 5

[0095] Compositions A8-A13 and E14-E17 were evaluated for haze, light defects, surface roughness, and scratches on polished silicon wafers. The compositions comprised 0.2 wt.% colloidal silica, 0.0012 wt.% ethylenediaminetetraacetic acid, 0.0004 wt.% nitric acid, 0.009 wt.% HEC (MW 250,000 g / mol), 0.006 wt.% PVP (MW 9,6000 g / mol), 0.0025 wt.% PEO-PPO (MW 2,100 g / mol), and 30 ppm of the preservative KATHON™ LX 150 (Dow Chemical). All compositions were adjusted to a pH of 10.5 with ammonia. The particle size distribution of the colloidal silica was measured by dynamic light scattering using a Malvern Mastersizer S (Malvern Instruments). D50, particle size distribution factor, slope coefficient, and steepness coefficient were obtained as described above and are listed in Table 3. The composition was used to polish the silicon wafer described in Example 3, and then the silicon wafer was cleaned as described in Example 3. Haze, light point defects, surface roughness, scratches, and microcracks were measured and evaluated as described in Example 3 and are listed in Table 3.

[0096] Table 3

[0097] As can be seen from Table 3 above, a low particle size distribution factor, a high steepness coefficient and a small slope coefficient have better effects, such as obtaining low light point defects, haze, surface roughness, etc.

[0098] Example 6:

[0099] Hydroxyethylcellulose (HEC) with varying glass transition temperatures was evaluated in A14-A18 and E18-E21 to analyze the effects of varying HEC glass transition temperatures on the compositions. All compositions contained 0.2 wt% colloidal silica, 0.0012 wt% ethylenediaminetetraacetic acid, 0.0004 wt% nitric acid, 0.009 wt% HEC (MW 250,000 g / mol) (with varying glass transition temperatures as listed in Table 4), 0.006 wt% PVP (MW 8,000 g / mol), 0.0025 wt% PEO-b-PPO (MW 5,800 g / mol), and 30 ppm (by weight) of the preservative KATHON™ LX 150 (Dow Chemical). The pH of all components was adjusted to 10.5 with ammonia. This composition was used to polish the silicon wafer described in Example 3, and then cleaned as described in Example 3.

[0100] The glass transition temperatures of HECs of all compositions were obtained by differential scanning calorimetry (DSC). The DSC of different HECs was examined on dried powders using a TA Instruments DSC (Model: SDT Q600, USA). The heating rate was fixed at 5°C / min under N2 atmosphere.

[0101] The slope coefficient was measured and obtained as described above.

[0102] Table 4

[0103] Examples E18-E21 have lower glass transition temperatures, and the results show that they have the best polishing effect.

[0104] Figure 1 shows differential scanning calorimetry results for HEC from compositions A17, A18, and E18 heated at a constant rate of 5°C / min. The X-axis represents temperature in °C, and the Y-axis represents heat flow divided by the sample weight in the indicated direction.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A chemical mechanical polishing composition comprising an abrasive, a first polymer and a second polymer, wherein the dispersion degrees of the first polymer and the second polymer are both at most 2.3, and the glass transition temperature of the first polymer is lower than 160°C.

2. The composition according to claim 1, characterized in that Also included is a surfactant, wherein the surfactant has a dispersity of at most 2.

3.

3. The composition according to claim 1, characterized in that The glass transition temperature of the second polymer is lower than 160°C.

4. The composition according to any one of claims 1 to 3, characterized in that The abrasive material is colloidal abrasive particles, wherein the ratio of the glass transition temperature of the first polymer to the slope coefficient of the colloidal abrasive particles is at least 10.

5. A colloidal silica abrasive for use in the chemical mechanical polishing composition according to any one of claims 1 to 4.

6. The colloidal silica abrasive according to claim 5, characterized in that: The colloidal silica abrasive has a slope coefficient of at most 17.

7. The colloidal silica abrasive according to claim 5, characterized in that: The colloidal silica abrasive has a steepness coefficient of at least 34.

8. The colloidal silica abrasive according to claim 5, characterized in that The colloidal silica abrasive has a particle size distribution factor of at most 1.

8.

9. The colloidal silica abrasive according to claim 5, characterized in that: The colloidal silica abrasive has a zeta potential of at least -3 mV at pH 9 to 12.

10. A polishing method for a silicon-containing substrate, the method being implemented using the composition according to any one of claims 1 to 4, and the composition being used in a final polishing step.

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