A chemical mechanical polishing composition for shallow trench isolation process and a polishing method thereof

Abstract

The present application provides a chemical mechanical polishing composition for shallow trench isolation process and a polishing method thereof. In the chemical mechanical polishing composition, cerium oxide abrasive particles and a protein are included, the molecular weight of the protein is less than 50 kDa, and the pH value of the composition is higher than the isoelectric point of the protein, so as to improve the selectivity ratio of silicon oxide to silicon nitride.

Description

Technical Field

[0001] This application relates to the field of chemical mechanical polishing technology, and more particularly to a chemical mechanical polishing composition and polishing method for shallow trench isolation processes. Background Technology

[0002] In the Shallow Trench Isolation (STI) process, a layer of silicon nitride (Si3N4) needs to be deposited on a silicon substrate, and silicon oxide trenches are formed in the silicon substrate through an etching process. These silicon oxide trenches are then filled with silicon dioxide (SiO2), and the surface is planarized by chemical mechanical polishing (CMP). CMP needs to efficiently remove the silicon oxide filling the trenches while retaining the silicon nitride as a stop layer.

[0003] However, existing chemical mechanical polishing compositions have relatively low selectivity for silicon oxide and silicon nitride, which can easily lead to premature wear through of the silicon nitride layer, causing morphological defects such as pitting and erosion, and affecting device performance.

[0004] Therefore, there is an urgent need to develop a technical solution that can significantly improve the selectivity of silicon oxide to silicon nitride in the STI process, so as to overcome the morphology defects caused by insufficient selectivity in the existing technology. Summary of the Invention This application provides a chemical mechanical polishing composition and polishing method for shallow trench isolation processes. A protein with an isoelectric point lower than the pH value of the composition is added to the chemical mechanical polishing composition to improve the selectivity of silicon oxide to silicon nitride.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions: In a first aspect, embodiments of this application provide a chemical mechanical polishing composition for chemical mechanical polishing in a shallow trench isolation process, characterized in that it comprises cerium oxide abrasive particles and a protein, wherein the molecular weight of the protein is less than 50 kDa, and the pH value of the composition is higher than the isoelectric point of the protein.

[0006] According to some embodiments of this application, the pH value of the composition is 4-7.

[0007] According to some embodiments of this application, the pH value of the composition is 5-7.

[0008] According to some embodiments of this application, the isoelectric point of the protein is below 5.

[0009] According to some embodiments of this application, the molecular weight of the protein is less than 20 kDa.

[0010] According to some embodiments of this application, the protein includes at least one of a complete protein or a hydrolyzed protein.

[0011] According to some embodiments of this application, the intact protein includes at least one selected from lactalbumin, whey protein, casein, silk protein, soy protein, corn protein, wheat protein, pea protein, potato protein, rice protein, cottonseed protein, rapeseed protein, sunflower protein, peanut protein, fish protein, and serum protein; the hydrolyzed protein includes a hydrolysis product of at least one selected from lactalbumin, whey protein, casein, silk protein, soy protein, corn protein, wheat protein, pea protein, potato protein, rice protein, cottonseed protein, rapeseed protein, sunflower protein, peanut protein, fish protein, and serum protein.

[0012] According to some embodiments of this application, the protein is lactalbumin.

[0013] According to some embodiments of this application, the composition further includes a removal rate enhancer, said removal rate enhancer comprising tetramethylethylenediamine.

[0014] In a second aspect, embodiments of this application provide a chemical mechanical polishing method for a shallow trench isolation process, wherein the method utilizes a composition as described in any one of the first aspects above to achieve chemical mechanical polishing of the shallow trench isolation process. Detailed Implementation

[0015] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0016] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” used herein may also include the plural forms. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or that other features, integers, steps, operations, elements, components, and / or groups may be added to the system / method.

[0017] In this application, "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. That is, X can include any combination of A, B, and C, or any combination of A, B, and C, as well as other possible content / elements. The arbitrary combination of A, B, and C can be A, B, C, AB, AC, BC, or ABC.

[0018] In modern semiconductor manufacturing processes, STI (Surface Mount Technology) is widely used to achieve electrical isolation between adjacent active regions, suppressing short-channel effects and increasing device integration density. A typical STI process flow includes: sequentially forming a silicon oxide layer and a silicon nitride layer on a silicon substrate; after photolithography and dry etching, shallow trenches are formed in the silicon substrate. Subsequently, the trenches are filled with silicon dioxide (SiO2) using methods such as high-density plasma chemical vapor deposition. Finally, CMP (Chemical Motion Processing) is used to remove excess silicon oxide from the surface until the silicon nitride layer is exposed, completing planarization.

[0019] In the above process, the selectivity ratio of silicon oxide to silicon nitride (i.e., the ratio of silicon oxide removal rate to silicon nitride removal rate) is a key parameter determining the quality of the STI structure. Ideally, chemical mechanical polishing should efficiently remove the filling silicon oxide layer while retaining the silicon nitride layer to the maximum extent possible.

[0020] However, the chemical mechanical polishing compositions used in the prior art suffer from a low selectivity ratio of silicon oxide to silicon nitride. This low selectivity causes the silicon nitride layer to be worn through prematurely, leading to morphological defects.

[0021] In view of this, this application provides a chemical mechanical polishing composition (hereinafter referred to as the composition) for shallow trench isolation processes and a polishing method thereof, wherein the composition includes cerium oxide abrasive particles and protein. The protein has a molecular weight of less than 50 kDa, and the pH value of the composition is higher than the isoelectric point of the protein. The combined effect of the protein and the cerium oxide abrasive particles improves the selectivity ratio of silicon oxide to silicon nitride, thereby solving the morphology defect problem caused by insufficient selectivity ratio of silicon oxide to silicon nitride.

[0022] The composition includes cerium oxide abrasive grains. The cerium oxide abrasive grains provide both chemical reaction and mechanical abrasive action. The cerium oxide abrasive grains include, but are not limited to, spherical cerium oxide abrasive grains, polyhedral cerium oxide abrasive grains, plate-like cerium oxide abrasive grains, blocky cerium oxide abrasive grains, needle-like cerium oxide abrasive grains, rod-like cerium oxide abrasive grains, or polycrystalline aggregated cerium oxide abrasive grains. The polyhedral cerium oxide abrasive grains can be at least one of cubic cerium oxide abrasive grains, octahedral cerium oxide abrasive grains, or chamfered octahedral cerium oxide abrasive grains.

[0023] Cerium oxide abrasive grains can be in powder form obtained by high-temperature calcination. Cerium oxide abrasive grains can also be colloidal cerium oxide abrasive grains dispersed in a liquid. In a particularly preferred embodiment, the cerium oxide abrasive grains are colloidal cerium oxide abrasive grains dispersed in a liquid.

[0024] In some embodiments, the cerium oxide abrasive grains are doped cerium oxide abrasive grains. Suitable dopants are, for example, metal ions (such as Ca, Mg, Zn, Zr, Sc, Y) or lanthanides (such as lanthanum, praseodymium, neodymium, promethium, or samarium). However, it has been found that the abrasive grains of the present invention can exhibit high removal rates even without dopants. Therefore, the cerium oxide abrasive grains are substantially dopant-free. Dopants may exist as impurities in the abrasive grains, and these impurities may originate from the raw materials or starting materials used to prepare the abrasive grains.

[0025] It should be noted that the cerium oxide abrasive grains may contain impurities. These impurities originate from the raw materials or processes used to prepare the abrasive grains and can be considered as not being part of the abrasive grain mixture; that is, these impurities are not added to the composition as a single component. This means that the impurities are not added in actual mass. The actual mass of the present invention is less than 30 ppm, further less than 20 ppm, further less than 10 ppm, and further less than 1 ppm. Here, ppm refers to weight ppm. It should be noted that the cerium oxide abrasive grains in this composition are preferably free of impurities. For ease of illustration, the following description will use 100 wt% cerium oxide abrasive grains that are free of impurities.

[0026] The composition contains cerium oxide abrasive particles at a weight ratio between 0.01 wt% and 10 wt%. In some embodiments, the composition contains cerium oxide abrasive particles at a weight ratio between 0.05 wt% and 5 wt%. In some embodiments, the composition contains cerium oxide abrasive particles at a weight ratio between 0.1 wt% and 3 wt%. Further, the weight ratio of cerium oxide abrasive particles in the composition can be selected as 0.01 wt%-0.05 wt%, 0.05 wt%-0.1 wt%, 0.1 wt%-0.5 wt%, 0.5 wt%-1 wt%, 1 wt%-1.5 wt%, 1.5 wt%-2 wt%, 2 wt%-2.5 wt%, 2.5 wt%-3 wt%, 3 wt%-3.5 wt%, 3.5 wt%-4 wt%, 4 wt%-4.5 wt%, 4.5 wt%-5 wt%, 5 wt%-5.5 wt%, 5.5 wt%-6 wt%, 6 wt%-6.5 wt%, 6.5 wt%-7 wt%, 7 wt%-7.5 wt%, 7.5 wt%-8 wt%, 8 wt%-8.5 wt%, 8.5 wt%-9 wt%, 9.5 wt%. Between wt% and 10 wt%. It is understood that the above range of cerium oxide abrasive grain weight percentages can be arbitrarily combined; for example, the weight percentage of cerium oxide abrasive grains in the composition may range from 1.5 wt% to 3.5 wt%. It is understood that the above weight percentages refer to the weight percentage of cerium oxide abrasive grains when the composition is used.

[0027] Cerium ions on the surface of cerium oxide abrasives form Ce-O-Si bonds with higher bond energy on the silanol groups on the surface of silica, thus removing the silica through physical forces. However, cerium oxide cannot form Ce-N-Si bonds with the silanol groups on the surface of silicon nitride, thereby selectively removing silica, improving the selectivity of the removal rate, and preventing premature wear through the silicon nitride layer and the resulting morphological defects in the STI process. Cerium oxide abrasive particles have a negative zeta potential at pH values ​​of 5-7. Specifically, cerium oxide abrasive particles have a zeta potential of -12mV to -60mV at pH values ​​of 5-7. In some embodiments, cerium oxide abrasive particles have a zeta potential of -25mV to -40mV at pH values ​​of 5-7. Furthermore, the cerium oxide abrasive particles in the composition have zeta potentials of -12mV to -15mV, -15mV to -20mV, -20mV to -25mV, -25mV to -30mV, -30mV to -35mV, -35mV to -40mV, -40mV to -45mV, -45mV to -50mV, -50mV to -55mV, and -55mV to -60mV at pH values ​​of 5-7. It is understood that the zeta potentials of the aforementioned cerium oxide abrasive particles at pH values ​​of 5-7 can be arbitrarily combined; for example, the cerium oxide abrasive particles may have a zeta potential of -20 to -35mV at pH values ​​of 5-7.

[0028] Cerium oxide abrasive grains can have any range of particle size distribution. For example, the average particle size of cerium oxide abrasive grains, as measured by scanning electron microscopy, is 10 nm to 200 nm. In some embodiments, the average particle size of cerium oxide abrasive grains, as measured by scanning electron microscopy, is 20 nm to 100 nm. Furthermore, the average particle size of cerium oxide abrasive particles, measured by scanning electron microscopy, is 10nm-20nm, 20nm-30nm, 30nm-40nm, 40nm-50nm, 50nm-60nm, 60nm-70nm, 70nm-80nm, 80nm-90nm, 90nm-100nm, 100nm-110nm, 110nm-120nm, 120nm-130nm, 130nm-140nm, 140nm-150nm, 150nm-160nm, 160nm-170nm, 170nm-180nm, 180nm-190nm, and 190nm-200nm. The average particle size refers to the arithmetic mean of the maximum distance between two points on the particle boundary.

[0029] The composition includes a liquid carrier. The liquid carrier can contain other components of the composition besides the liquid carrier itself, suspending these components in the liquid carrier and allowing them to contact the substrate for polishing. The liquid carrier can be an aqueous carrier, or any component suitable for suspending cerium oxide abrasive particles and chemical additives. The liquid carrier can be one of water, ethers (such as dioxane and tetrahydrofuran), and alcohols (such as methanol and ethanol), or a combination of water, ethers (such as dioxane and tetrahydrofuran), and alcohols (such as methanol and ethanol). When the liquid carrier is a combination of multiple components, the liquid carrier contains at least 50 wt% water, for example, the aqueous carrier contains 50 wt% water, 70 wt% water, 90 wt% water, 95 wt% water, or 99 wt% water. The liquid carrier is water. Further, the water is deionized water.

[0030] The composition includes a protein. The protein acts as both a dispersant for cerium oxide abrasive particles and a silicon nitride inhibitor. Specifically, the protein reversibly adsorbs onto the surface of positively charged cerium oxide abrasive particles, changing the zeta potential of the cerium oxide particles from positive to negative, forming negatively charged composite abrasive particles. The protein then adsorbs onto the surface of positively charged silicon nitride through electrostatic attraction, changing the zeta potential of silicon nitride from positive to negative, creating electrostatic repulsion with the negatively charged abrasive particles, significantly reducing the silicon nitride removal rate. Simultaneously, the protein's molecular structure contains polar groups, such as -COOH, -NH2, and -OH. These polar groups can form hydrogen bonds or weak chemical interactions with the silanine groups on the silicon nitride surface, reducing the hydrolysis of silanine groups and further reducing the silicon nitride removal rate. Without sacrificing silicon oxide removal efficiency, the composition effectively protects the silicon nitride stop layer, thereby significantly improving the selectivity ratio of silicon oxide to silicon nitride, ensuring the morphological integrity of the STI structure and process yield.

[0031] The proteins in this scheme are small to medium-sized proteins. In some embodiments, the molecular weight of the protein is less than 50 kDa. In some embodiments, the molecular weight of the protein is less than 20 kDa. Further, in some embodiments, the molecular weight of the protein ranges from 0.1 kDa to 50 kDa. In some embodiments, the molecular weight of the protein ranges from 5 kDa to 30 kDa. Even further, the molecular weight of the protein is 0.1 kDa-1 kDa, 1 kDa-5 kDa, 5 kDa-10 kDa, 10 kDa-15 kDa, 15 kDa-20 kDa, 20 kDa-25 kDa, 25 kDa-30 kDa, 30 kDa-35 kDa, 35 kDa-40 kDa, 40 kDa-45 kDa, or 45 kDa-50 kDa. It is understood that the above-mentioned molecular weights of proteins can be arbitrarily combined; for example, the molecular weight of the protein may be 5 kDa-20 kDa.

[0032] The protein may include at least one of intact proteins or hydrolyzed proteins. The intact protein includes at least one of lactalbumin, whey protein, casein, silk protein, soy protein, corn protein, wheat protein, pea protein, potato protein, rice protein, cottonseed protein, rapeseed protein, sunflower protein, peanut protein, fish protein, and serum protein. The hydrolyzed protein includes the hydrolysis product of at least one of lactalbumin, whey protein, casein, silk protein, soy protein, corn protein, wheat protein, pea protein, potato protein, rice protein, cottonseed protein, rapeseed protein, sunflower protein, peanut protein, fish protein, and serum protein. In a particularly preferred embodiment, the protein is lactalbumin.

[0033] The isoelectric point (IEP) of a protein is a key parameter in the characterization of its physicochemical properties. The IEP is the pH value at which the protein's net charge in a composition is zero. At the isoelectric point, protein molecules are uncharged, do not migrate in an electric field, and typically have the lowest solubility, making them prone to precipitation or aggregation.

[0034] The isoelectric point of the protein is below 8. Further, the isoelectric point of the protein is below 5. Specifically, in some embodiments, the isoelectric point range of the protein is 1-5. In some embodiments, the isoelectric point range of the protein is 2-5. Further, the isoelectric point range of the protein is 1-2, 2-3, 3-4, or 4-5. It is understood that the above-mentioned isoelectric point ranges of the protein can be arbitrarily combined; for example, the isoelectric point range of the protein is 1-4.

[0035] In some embodiments, the pH value of the composition can be 4-7. In some embodiments, the pH value of the composition can be 5-7. Further, the pH value of the composition can be 5.5-6.5. Further, the pH value of the composition is 4-5, 5-6, or 6-7.

[0036] The pH value of a composition can significantly affect the charge state, solubility, conformational stability, aggregation tendency, and biological activity of proteins. Specifically, when the pH value of the composition is close to the isoelectric point (IEP) of the protein, the net charge of the protein approaches zero, the electrostatic repulsion between molecules weakens, leading to decreased solubility and making it prone to aggregation, precipitation, or even inactivation. Conversely, when the pH value of the composition is higher than the isoelectric point (IEP) of the protein, the protein surface carries a net negative charge, and the molecules maintain good dispersibility due to the repulsion of like charges.

[0037] The isoelectric point of a protein is lower than the pH value of the composition; that is, the pH value of the composition is higher than the isoelectric point of the protein. For example, as mentioned above, the pH range of the composition is 4-7, and the isoelectric point range of the protein is 1-5. Therefore, when the pH value of the composition is 4, the isoelectric point of the protein can be 3, 2, or 1, but not 5. As another example, when the pH value of the composition is 7, the isoelectric point of the protein can be any number from 1 to 6.

[0038] The protein weight percentage in the composition is between 0.05 wt% and 5 wt%. In some embodiments, the protein weight percentage in the composition is between 0.1 wt% and 1.0 wt%. In some embodiments, the protein weight percentage in the composition is between 0.3 wt% and 0.8 wt%. Further, the protein weight percentage in the composition can be selected to be between 0.05 wt% and 0.08 wt%, 0.08 wt% and 0.1 wt%, 0.1 wt% and 0.2 wt%, 0.2 wt% and 0.3 wt%, 0.3 wt% and 0.4 wt%, 0.4 wt% and 0.5 wt%, 0.5 wt% and 0.6 wt%, 0.6 wt% and 0.7 wt%, 0.7 wt% and 0.8 wt%, 0.8 wt% and 0.9 wt%, 0.9 wt% and 1 wt%, 1 wt% and 2 wt%, 2 wt% and 3 wt%, 3 wt% and 4 wt% and 5 wt%. It is understood that the above-mentioned protein weight ratio ranges can be arbitrarily combined; for example, the protein weight ratio in the composition ranges from 0.05 wt% to 0.5 wt%.

[0039] The composition also includes a removal rate enhancer. The removal rate enhancer can improve the removal rate of silica (such as silicon dioxide) by cerium oxide abrasive particles. Specifically, the removal rate enhancer improves the removal rate of silica by cerium oxide abrasive particles through contact with the Ce2O3 surface of the cerium oxide abrasive particles. 4+ / Ce 3+ Site coordination modulates the surface charge state of cerium oxide abrasive particles and enhances their interaction with the silicon oxide surface. Simultaneously, the removal rate enhancer promotes the deprotonation of silanol groups (Si-OH) on the silicon oxide surface, forming hydrophilic Si-O that is more easily mechanically sheared or chemically activated. - Group.

[0040] Removal enhancement agents contain amine compounds. These amine compounds may contain one or more amino groups. Specifically, the diamine containing two amino groups is at least one of a linear primary diamine, a branched diamine, a cyclic diamine, or an aromatic diamine. Polyamines may include N,N,N′,N′,N”-pentamethyldiethylenetriamine (PMDETA) or polyethyleneimine (PEI).

[0041] The linear primary diamine includes at least one of diaminomethane, 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-diaminodecane, 1,11-undecanediamine, and 1,12-dodecanediamine.

[0042] Branched diamines include at least one of 1,2-diaminopropane, diphenylethylenediamine, 1,2-diaminocyclohexane, 3-(diethylamino)propylamine, 3-(dibutylamino)propylamine, 3-(methylamino)propylamine, 3-(dimethylamino)propylamine, tetramethylethylenediamine, tetramethylenediamine, bis(dimethylamino)methane, dimethylethylenediamine, ethylethylenediamine, methyl-1,3-propanediamine, 1,3-diaminopentane, isopropylethylenediamine, isopropyl-1,3-propanediamine, tetramethylethylenediamine, tetramethylpropanediamine, tetramethyl-1,2-propanediamine, 2,2-tetramethyl-1,3-propanediamine, dimethyl-1,6-diaminohexane, tetramethyl-2,2-dimethyl-1,3-propanediamine, tetramethylhexamethylenediamine, and 3-aminopropyl-1,3-propanediamine.

[0043] Cyclic diamines include 1,4-diazacycloheptane, 1,4-diazacycloheptane, trimethylenediamine, and combinations thereof. Examples of aromatic diamines include at least one of phenylenediamine, dimethyl-4-phenylenediamine, di-2-butyl-1,4-phenylenediamine, diaminobiphenyl, diaminonaphthalene, and xylenediamine.

[0044] In a preferred embodiment, the removal rate enhancer includes tetramethylethylenediamine, tetramethylpropylenediamine, and pentamethyldiethylenetriamine.

[0045] The removal rate enhancer in this composition is present in a weight ratio between 0.001 wt% and 1 wt%. In some embodiments, the removal rate enhancer in this composition is present in a weight ratio between 0.003 wt% and 0.8 wt%. In some embodiments, the removal rate enhancer in this composition is present in a weight ratio between 0.005 wt% and 0.3 wt%. Furthermore, the weight ratio of the removal rate enhancer in the composition can be selected to be between 0.001wt%-0.003wt%, 0.003wt%-0.005wt%, 0.005wt%-0.01wt%, 0.01wt%-0.05wt%, 0.05wt%-0.08wt%, 0.08wt%-0.1wt%, 0.1wt%-0.2wt%, 0.2wt%-0.3wt%, 0.3wt%-0.4wt%, 0.4wt%-0.5wt%, 0.5wt%-0.6wt%, 0.6wt%-0.7wt%, 0.7wt%-0.8wt%, 0.8wt%-0.9wt%, and 0.9wt%-1wt%. It is understood that the above-mentioned range of removal rate enhancer weight ratio can be arbitrarily combined, for example, the weight ratio of removal rate enhancer in the composition is between 0.05 wt% and 0.5 wt%.

[0046] The composition also includes a wetting agent. The wetting agent can reduce the interfacial tension between the composition and the silicon oxide surface, improve the spreadability and penetration of the composition on the silicon oxide surface, ensure that the abrasive grains are evenly distributed on the silicon oxide surface during polishing, prevent uneven local reactions, and thus improve polishing uniformity.

[0047] The wetting agent comprises a water-soluble polymer. This water-soluble polymer can be a homopolymer, copolymer, or a combination thereof. The water-soluble polymer can be neutral in the composition, and can be positively or negatively charged. As used herein, the term "water-soluble" means a polymer having a solubility of at least 0.1 mg / ml in water at 25°C. Preferably, the water-soluble polymer is freely soluble in water at 25°C.

[0048] Water-soluble polymers include polyvinylpyrrolidone, polyoxyethylene, polyvinylacetamide, polyglycerol, polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polytetramethylene ether glycol (PTMEG), functionalized PEG, hydrophobically modified PEG, polyethylene oxide, polyethylene glycol (PEG)-polypropylene glycol (PPG) block copolymers, polyether polyol copolymers, fatty alcohol alkoxylates, terminal fatty alcohol alkoxylates, ethylenediamine adducts of epoxy alkyl groups, polyethyloxazoline, and polycarboxylic acids (such as...). Polyacrylic acid, polyacrylates, polysulfonic acids (e.g., polyphosphonic acid, polystyrene sulfonic acid), polyvinyl alcohol, polyvinylpyrrolidone, sorbitan monooleate, oxyalkylene polymers, poly(hydroxyethyl methacrylate), poly(hydroxyethyl methacrylate), copolymers of poly(hydroxyethyl methacrylate), copolymers of poly(hydroxyethyl methacrylate), polysaccharides, cellulose derivatives (e.g., hydroxypropyl cellulose, hydroxyethyl cellulose), methacryloyloxyethyltrimethylammonium, synthetic polymers (e.g., xanthan gum, sodium alginate), and combinations thereof. In a particularly preferred embodiment, the water-soluble polymer includes at least one of polyethylene glycol, polypropylene glycol, polyglycerol, polyoxyethylene, hydroxyethyl cellulose, polyvinyl alcohol, and polyvinylpyrrolidone.

[0049] The water-soluble polymer should have a suitable molecular weight (MW). The molecular weight of the water-soluble polymer used in this specification refers to its weight-average molecular weight. The molecular weight range of the water-soluble polymer is 200 g / mol to 20,000 g / mol. In some embodiments, the molecular weight range of the water-soluble polymer is 500 g / mol to 18,000 g / mol. In some embodiments, the molecular weight range of the water-soluble polymer is 1000 g / mol to 15,000 g / mol. Furthermore, the molecular weight range of the water-soluble polymer is 200 g / mol-500 g / mol, 500 g / mol-800 g / mol, 800 g / mol-1000 g / mol, 1000 g / mol-1500 g / mol, 1500 g / mol-2000 g / mol, 2000 g / mol-2500 g / mol, 2500 g / mol-3000 g / mol, 3000 g / mol-3500 g / mol, 3500 g / mol-4000 g / mol, 4000 g / mol-4500 g / mol, 4500 g / mol-5000 g / mol, 5000 g / mol-5500 g / mol, 5500 g / mol-6000 g / mol, 6000 g / mol-6500 g / mol, 6500 g / mol-7000 g / mol. g / mol, 7000 g / mol-7500 g / mol, 7500 g / mol-8000 g / mol, 8000g / mol-8500 g / mol, 8500 g / mol-9000 g / mol, 9000 g / mol-9500 g / mol, 9500 g / mol-10000g / mol, 10000 g / mol-11000 g / mol, 11000 g / mol-12000 g / mol, 12000 g / mol-13000 g / mol, 13000 g / mol-14000 g / mol, 14000 g / mol-15000 g / mol, 15000 g / mol-16000 g / mol, 16000 g / mol-17000 g / mol, 17000 g / mol-18000 g / mol, 18000 g / mol-19000 g / mol, 19000 g / mol-20000 g / mol. It is understood that the molecular weight ranges of the above-mentioned water-soluble polymers can be arbitrarily combined; for example, the molecular weight range of the water-soluble polymers in the composition is between 500 g / mol and 13000 g / mol.

[0050] The water-soluble polymer in the composition is between 0.0001 wt% and 5 wt%. In some embodiments, the wetting agent in the composition is between 0.001 wt% and 0.05 wt%. Further, the weight ratio of the wetting agent in the composition can be selected to be between 0.0001wt%-0.001wt%, 0.001wt%-0.01wt%, 0.01wt%-0.05wt%, 0.05wt%-0.08wt%, 0.08wt%-0.1wt%, 0.1wt%-0.2wt%, 0.2wt%-0.3wt%, 0.3wt%-0.4wt%, 0.4wt%-0.5wt%, 0.5wt%-0.6wt%, 0.6wt%-0.7wt%, 0.7wt%-0.8wt%, 0.8wt%-0.9wt%, 0.9wt%-1wt%, 1wt%-2wt%, 2wt%-3wt%, 3wt%-4wt%, and 4wt%-5wt%. It is understood that the above-mentioned range of wetting agent weight ratios can be arbitrarily combined; for example, the weight ratio of the wetting agent in the composition can be between 0.05 wt% and 0.5 wt%.

[0051] The composition further includes a pH adjuster and a pH buffer. Under the adjustment of the pH adjuster and pH buffer, the composition has the pH value described above. The pH adjuster includes alkali metal silicon hydroxide, quaternary ammonium silicon hydroxide, alkali metal carbonate, or combinations thereof. Further, the pH adjuster includes at least one selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, potassium hydroxide, sodium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, and ethanolamine. It should be noted that the composition described in this application may contain an appropriate amount of pH adjuster, the concentration of which is preferably such that the pH value required by the present invention can be achieved; the specific concentration range will not be elaborated here.

[0052] pH buffers help maintain a suitable pH value in the composition. A pH buffer can be any suitable buffer. For example, a pH buffer can be a carbonate, bicarbonate, phosphate, borate, organic buffer, or a combination thereof. Carbonates include sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, calcium carbonate, magnesium carbonate, and combinations thereof. Bicarbonates include sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, and combinations thereof. Phosphates include sodium phosphate, potassium phosphate, ammonium phosphate, and combinations thereof. Borates include sodium borate, potassium borate, and combinations thereof. Organic buffers include tris(hydroxymethyl)aminomethane (TRIS), sodium acetate, potassium acetate, ammonium acetate, sodium citrate, potassium citrate, ammonium citrate, and combinations thereof. In this embodiment, inorganic carbonates are preferred as pH buffers. Further, sodium carbonate, potassium carbonate, lithium carbonate, ammonium carbonate, carbonate, and magnesium carbonate are preferred as pH buffers. It should be noted that the composition described in this application may contain an appropriate amount of pH buffer, the concentration of which is preferably such that the pH value required to achieve the present invention is achieved; specific concentration ranges are not elaborated here.

[0053] Secondly, this application also provides a chemical mechanical polishing method for a shallow trench isolation process. The method includes the following steps: (a) providing the above-described chemical mechanical polishing composition; (b) bringing a substrate, the chemical mechanical polishing composition, and a polishing pad into contact; (c) moving the polishing pad relative to the substrate, with the chemical mechanical polishing composition positioned therebetween; and (d) removing at least a portion of the substrate. The method may optionally include other steps.

[0054] The composition can be prepared using suitable techniques known to those skilled in the art. The cerium oxide abrasive particles and other components, as described above, can be added to the liquid carrier in any order and in suitable amounts to achieve the desired concentration. The cerium oxide abrasive particles and other components can be mixed and stirred in the liquid carrier. The pH value can be adjusted using the pH adjuster and pH buffer described above to obtain and maintain the desired pH. The cerium oxide abrasive particles and other components can be added at any time before use or during CMP treatment.

[0055] The composition can be provided as a single-part system, a two-part system, or a multi-part system. For example, as a two-part system, the first part may include cerium oxide abrasive particles, and the second part may include one or more other components. The first and second parts can be mixed at any time before or during the CMP treatment.

[0056] The following are specific embodiments of the compositions designed according to the above disclosure. It should be understood that the following embodiments are merely illustrative of the compositions and polishing methods disclosed above, and the specific implementation methods and parameters used are only one or more of the numerous parameters and methods described above. Those skilled in the art can use other parameters to perform chemical mechanical polishing according to the above methods without departing from the core spirit of the disclosure.

[0057]

Preparation of the Composition

[0058]

Measurement

[0059] The method for measuring silicon nitride loss is as follows: After polishing the 8-inch STI wafer to its final state, continue polishing for 60 seconds. Then measure the remaining thickness of silicon nitride in the active area of ​​each region and compare it with the initial thickness of silicon nitride at that location. The difference is the silicon nitride loss.

[0060] Example 1 Compositions A1-A3 and E1-E5 each contain 0.5 wt.% cerium oxide abrasive particles and 0.05 wt.% polyethylene glycol (PEG). Except for composition A1, all other compositions additionally contain 0.5 wt.% of the proteins listed in Table 1. Composition E3 also contains an additional 0.01 wt% tetramethylethylenediamine (TMEDA). The pH of each composition was adjusted using KOH to the values ​​shown in Table 1.

[0061] The above method was used to polish silicon oxide unpatterned wafers and silicon nitride unpatterned wafers, and their removal rates (RR) are listed in Table 1. The selection ratio is the ratio of the silicon oxide removal rate (simplified as silicon oxide RR) to the silicon nitride removal rate (simplified as silicon nitride RR).

[0062] Table 1

[0063] in conclusion: (1) Compared with other compositions, composition A1 without added protein exhibits a higher silicon nitride removal rate and a lower selectivity; (2) Among compositions E1-E5, the compositions with the isoelectric point of the protein being lower than the pH value of the composition exhibit a lower silicon nitride removal rate and a higher selectivity. (3) Composition E3 containing tetramethylethylenediamine exhibits a higher silica removal rate compared to composition E2 which does not contain tetramethylethylenediamine.

[0064] Example 2 Compositions A4, A5, and E6 each contain 0.5 wt.% cerium oxide, 0.05 wt.% polyethylene glycol (PEG), and 0.01 wt.% tetramethylethylenediamine. Compositions A5 and E6 also additionally contain 0.5 wt.% of the proteins listed in Table 2. The pH of all compositions was adjusted to the values ​​shown in Table 2 using KOH.

[0065] The removal rate of activated silicon oxide was measured using a JAWoollam M-2000X elliptic polarization spectrometer according to the method described above. The silicon nitride loss after 30 seconds of polishing is listed in nanometers (nm) in Table 2.

[0066] The linewidth of the first region is 500 μm and the density of the active region is 50%; the linewidth of the second region is 1000 μm and the density of the active region is 50%; the linewidth of the active region in the third region is 4 mm and the density of the active region is 100%.

[0067] Table 2

[0068] in conclusion: Compared to compositions A4 and A5, composition E6, with a pH value higher than the isoelectric point of proteins, showed improved silicon nitride loss.

[0069] In summary, the addition of protein to the composition, whose isoelectric point is lower than the pH value of the composition, and the combined effect of protein and cerium oxide abrasive particles, improves the removal rate of silica and reduces the loss of silicon nitride, thereby increasing the selectivity ratio of silica to silicon nitride and solving the morphology defect problem caused by insufficient selectivity ratio of silica to silicon nitride.

[0070] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve the desired results. In some implementations, multitasking and parallel processing are also possible or may be advantageous.

[0071] In summary, after reading this detailed disclosure, those skilled in the art will understand that the foregoing detailed disclosure may be presented by way of example only and may not be restrictive. Although not explicitly stated herein, those skilled in the art will understand that this specification requires various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0072] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, "an embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is to be emphasized and understood that two or more references to "an embodiment" or "an embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, specific features, structures, or characteristics may be suitably combined in one or more embodiments of this specification.

[0073] It should be understood that in the foregoing description of the embodiments in this specification, various features are combined in a single embodiment or its description for the purpose of simplifying the description and aiding in the understanding of a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may extract some of the features as separate embodiments when reading this specification. That is, the embodiments in this specification can also be understood as an integration of multiple sub-embodiments. It is also valid when each sub-embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

[0074] Every patent, patent application, publication of a patent application, and other material, such as articles, books, specifications, publications, documents, and literature (excluding any related historical examination documents), cited in this disclosure is incorporated herein for all purposes, including, for example, in the specification and claims of this disclosure. However, in the event of any inconsistency or conflict between the descriptions, definitions, and / or terms used in the foregoing and those used in this disclosure, the descriptions, definitions, and / or terms used in this disclosure shall prevail.

[0075] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments described in this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can implement the applications described in this specification using alternative configurations based on the embodiments in this specification. Therefore, the embodiments in this specification are not limited to the embodiments precisely described in the applications.

Claims

1. A chemical mechanical polishing composition for chemical mechanical polishing in shallow trench isolation processes, characterized in that, The composition includes cerium oxide abrasive particles and a protein, wherein the protein has a molecular weight of less than 50 kDa and the pH value of the composition is higher than the isoelectric point of the protein.

2. The composition according to claim 1, characterized in that, The pH value of the composition is 4-7.

3. The composition according to claim 1, characterized in that, The pH value of the composition is 5-7.

4. The composition according to claim 1, characterized in that, The isoelectric point of the protein is below 5.

5. The composition according to claim 1, characterized in that, The protein has a molecular weight of less than 20 kDa.

6. The composition according to claim 1, characterized in that, The protein includes at least one of a complete protein or a hydrolyzed protein.

7. The composition according to claim 6, characterized in that, The complete protein includes at least one of the following: lactalbumin, whey protein, casein, silk protein, soy protein, corn protein, wheat protein, pea protein, potato protein, rice protein, cottonseed protein, rapeseed protein, sunflower protein, peanut protein, fish protein, and serum protein. The hydrolyzed protein includes at least one hydrolysate of lactalbumin, whey protein, casein, silk protein, soy protein, corn protein, wheat protein, pea protein, potato protein, rice protein, cottonseed protein, rapeseed protein, sunflower protein, peanut protein, fish protein, and serum protein.

8. The composition according to claim 1, characterized in that, The protein in question is lactalbumin.

9. The composition according to claim 1, characterized in that, The composition further includes a removal rate enhancer, which includes at least one of tetramethylethylenediamine, tetramethylpropylenediamine, and pentamethyldiethylenetriamine.

10. A chemical mechanical polishing method for shallow trench isolation processes, characterized in that, The method utilizes the composition as described in any one of claims 1-9 to achieve chemical mechanical polishing of the shallow trench isolation process.

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