CMP aqueous slurry composition and application thereof

Abstract

The invention provides a chemical mechanical polishing water-based slurry composition which is applied to a shallow trench isolation (STI) process and comprises cerium dioxide abrasive particles, an electrolyte modifier and a nitrogen-containing chemical additive, and the water-based slurry composition can be used for automatically stopping polishing in the STI process. It minimizes non-uniformity after CMP and also extends the time the polishing can last beyond the end point without the risk of over-polishing the dielectric silica film.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and particularly relates to an aqueous slurry composition for a semiconductor chemical mechanical polishing (CMP) process, which is particularly suitable for a shallow trench isolation (STI) process. Background Art

[0002] In the manufacturing of semiconductor integrated circuits, as the device size continues to shrink and the integration level continues to increase, the chemical mechanical polishing (CMP) process has become a key technology for achieving global planarization of the wafer surface. Shallow trench isolation (STI) is a key technology in semiconductor manufacturing. Its principle is to etch shallow trenches on a semiconductor silicon wafer and then fill them with an insulating material (usually deposited oxides such as silicon dioxide), forming an insulating barrier between adjacent semiconductor device components, thereby preventing current leakage between different devices, avoiding mutual interference, and ensuring that each device can work independently and properly.

[0003] In semiconductor manufacturing, the STI CMP process needs to achieve a high selectivity polishing between SiO 2 and SiN to ensure the planarization effect and reduce dishing defects to ensure good device isolation effect and chip performance. In the global planarization of the patterned STI structure, reducing the oxide trench recession is a key factor to be considered. Lower trench oxide loss will prevent current leakage between adjacent transistors. Non-uniform trench oxide loss across the die will affect transistor performance and device manufacturing yield. Severe trench loss (high oxide trench recession) will lead to poor isolation of the transistor, resulting in device failure. Therefore, it is important to reduce the trench oxide loss by reducing the oxide trench recession in the STI CMP polishing composition. Versum Materials US LLC discloses in patents [CN110951399A], [CN118251471A], [TW202319144A], [US202403955558A1] that a polishing composition using cerium dioxide abrasive grains or cerium dioxide-coated silicon oxide abrasive grains as abrasives, and adding a polyelectrolyte and a chemical additive containing two or more hydroxyl functional groups for STI polishing applications can achieve low oxide trench recession. However, the inhibitory effect of this polishing composition on oxide trench recession is limited. As the overpolish time in CMP polishing extends, the differences in oxide trench recessions of various sizes on the patterned wafer are large, and the polishing uniformity is poor, unable to provide a more uniform oxide trench recession, making its application have certain limitations.

[0004] Therefore, it is of great significance to develop a CMP aqueous slurry composition that can provide a high selectivity ratio, good planarization efficiency, and low defect rate. Summary of the Invention

[0005] The object of the present invention is to provide an aqueous slurry composition for semiconductor chemical mechanical polishing (CMP) process, especially for shallow trench isolation (STI) process, which can achieve high selectivity polishing of silicon dioxide and silicon nitride films, improve the planarization efficiency when polishing patterned wafers, reduce dish-shaped defects, so as to meet the increasingly strict process requirements in semiconductor manufacturing.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a chemical mechanical polishing aqueous slurry composition for polishing semiconductor devices: the composition comprises cerium dioxide abrasive grains, an electrolyte modifier, a nitrogen-containing chemical additive, a pH regulator, a biocide, and ultrapure water;

[0008] Further, the electrolyte modifier is an organic polymer containing carboxylic acid, carboxylic acid ester or carboxylate, and has the following general molecular structure:

[0009]

[0010] Wherein R 1 is selected from H, alkyl, Na, K or NH 4 ; R 2 is selected from H or alkyl; n represents the number of repeating monomer units; the molecular weight range of the electrolyte modifier is selected from 500 - 500000, preferably the molecular weight range is selected from 500 - 10000, further preferably the molecular weight range is 500 - 3000, and more preferably the molecular weight is 1000 - 2000.

[0011] Preferably, the alkyl is selected from C1 - C6 alkyl; more preferably, the alkyl is selected from methyl or ethyl;

[0012] Further, the mass ratio of the nitrogen-containing chemical additive to the polyelectrolyte is 1:0.5 - 1:3;

[0013] Further, the nitrogen-containing chemical additive is selected from at least one of hydroxamic acid compounds, polyethyleneimine, branched polyethyleneimine or polyvinylamine;

[0014] Preferably, the nitrogen-containing chemical additive is selected from at least one of polyethyleneimine, branched polyethyleneimine or polyvinylamine, and more preferably at least one of polyethyleneimine and branched polyethyleneimine.

[0015] Further, the hydroxamic acid compound is selected from one or a combination of benzyl hydroxamic acid, acetyl hydroxamic acid, isohydroxamic acid, and salicylhydroxamic acid;

[0016] And / or, the branched polyethyleneimine is selected from polyether-branched polyethyleneimine, and the polyether is selected from at least one of polyoxyethylene, polyoxypropylene, and polyoxyethylene-polyoxypropylene copolymer.

[0017] More preferably, the molecular weight of the polyethyleneimine and the branched polyethyleneimine polymer is selected from 600 to 100,000, and more preferably the molecular weight is 800 to 50,000;

[0018] And / or, the polyvinylamine polymer is selected from polyvinylamine with a molecular weight of 600 to 100,000, preferably polyvinylamine with a molecular weight of 1000 to 20,000;

[0019] And / or, the organic polymer containing a carboxylic acid group or its salt is selected from one or a combination of polyacrylate, polyacrylic acid, ammonium polyacrylate, potassium polyacrylate, polymethacrylate, polymethacrylic acid, ammonium polymethacrylate, and potassium polymethacrylate;

[0020] Further, the mass content of the nitrogen-containing chemical additive in the slurry composition is 0.03 to 0.5%;

[0021] And / or, the mass content of the electrolyte modifier in the slurry composition is 0.1 to 0.3%.

[0022] Further, the pH of the composition is preferably 4 - 9, more preferably 4.5 - 7;

[0023] And / or, the pH regulator is selected from at least one of hydrochloric acid, phosphoric acid, acetic acid, propionic acid, citric acid, malonic acid, sulfonic acid, hydroxyethylsulfonic acid, aromatic carboxylic acid, and heteroaromatic carboxylic acid; preferably, the aromatic carboxylic acid is selected from at least one of benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, and salicylic acid; the heteroaromatic carboxylic acid is selected from at least one of picolinic acid and pyridinedicarboxylic acid;

[0024] And / or, in the slurry composition, the total solid mass content of the cerium dioxide grinding particles is 0.05 - 30%, preferably 0.05 - 10%, more preferably 0.5% - 5%;

[0025] And / or, the average particle size range of the cerium dioxide grinding particles is 10nm - 500nm, preferably the average particle size range is 50nm - 300nm, more preferably the average particle size range is between 50nm - 200nm;

[0026] And / or, the biocide content in the composition is 0.001% - 0.01%, and the biocide is selected from one or a combination of methylisothiazolinone, 5-chloro-2-methyl-4-isothiazolin-3-one, and benzisothiazolinone;

[0027] In a second aspect, the present invention provides the application of the above aqueous slurry composition in the manufacture of semiconductor devices;

[0028] In a third aspect, the present invention provides a polishing method for a semiconductor device wafer, characterized in that: the above aqueous slurry composition is used to contact the wafer for polishing.

[0029] In the present invention, after the cerium dioxide abrasive grains are coated with an electrolyte modifier, the surface charge changes from positive charge to negative charge. During the CMP polishing process, the negatively charged polyelectrolyte adsorbs on the SiN surface, inhibiting the polishing of SiN, ensuring a high selectivity ratio of OX / SiN. At the same time, when polishing a patterned wafer, the nitrogen-containing chemical additive will adsorb in the recessed area, inhibiting the further polishing of silicon oxide in the grooves, thereby providing better planarization efficiency and dishing defects.

[0030] Beneficial effects:

[0031] 1. Through the regulation of the surface charge of cerium dioxide abrasive grains by the electrolyte modifier and its adsorption on the SiN surface, a high selectivity ratio polishing of silicon dioxide and silicon nitride is achieved, effectively avoiding the over-polishing of silicon nitride and improving the electrical performance and stability of the device.

[0032] 2. Through the adsorption of the nitrogen-containing chemical additive in the recessed area of the patterned wafer, the polishing rate of silicon oxide in the grooves is inhibited, reducing the polishing rate difference between the convex and concave areas on the wafer surface, improving the planarization efficiency, and reducing dishing defects and surface non-uniformity. Description of the drawings

[0033] Figure 1 It is a schematic diagram of the action mechanism of the nitrogen-containing chemical additive in the present invention in CMP polishing. Detailed implementation manners

[0034] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the embodiments including the following examples and can be variously modified within the scope that can achieve the purpose of the invention and does not exceed the gist of the invention.

[0035] In the following embodiments, unless otherwise specifically stated, the raw material reagents or processing techniques used are common commercially available raw materials or conventional processing techniques in the art.

[0036] An embodiment of the present invention provides an aqueous slurry composition for polishing semiconductor devices. The composition includes cerium dioxide abrasive particles, an electrolyte modifier, a nitrogen-containing chemical additive, a pH regulator, a biocide, and ultrapure water.

[0037] <Semiconductor device>

[0038] In the present invention, the semiconductor device contains silicon oxide material and silicon nitride material, preferably a semiconductor device including a silicon dioxide and silicon nitride layer, such as a semiconductor substrate material like a wafer or a dielectric thin film.

[0039] In the STI formation step, after forming trenches as element isolation regions and forming a polishing stop film of silicon nitride on regions other than the grooves, an insulating film of silicon dioxide for element isolation is formed inside the grooves and on the polishing stop film. Then, the excess insulating film is removed by polishing via CMP until the above-mentioned polishing stop film appears and is planarized.

[0040] In the present invention, after the cerium dioxide abrasive grains in the aqueous slurry composition are coated with an electrolyte modifier, the surface charge changes from positive charge to negative charge, and it adsorbs on the surface of silicon nitride during the CMP polishing process, inhibiting SiN polishing and ensuring a high selectivity ratio of silicon oxide / silicon nitride. At the same time, when polishing a patterned wafer, the aqueous slurry composition has a high selectivity polishing effect on silicon dioxide on the surface of the semiconductor material, while inhibiting the polishing of silicon nitride; at the same time, the nitrogen-containing chemical additive in the aqueous slurry composition will adsorb in the recessed area, inhibiting the further polishing of silicon oxide in the grooves, thereby providing better planarization efficiency and dishing defects.

[0041] <Abrasive particles>

[0042] In the present invention, abrasive particles are a key material in the CMP (Chemical Mechanical Polishing) process for improving the surface finish of materials and removing unnecessary films or defects. Abrasives are usually composed of tiny particles, which act together with the polishing liquid and mechanical force during CMP to help achieve high-precision surface treatment.

[0043] In the present invention, the abrasive particles are preferably cerium dioxide abrasive grains. Ceria is an oxide of the rare earth metal cerium. The cerium dioxide abrasive grains have good chemical stability during polishing, are not easily chemically reacted with other components in the polishing liquid, and have less impact on the environment. During polishing, water molecules in the polishing liquid cause hydroxylation on the surface of the material to be polished (such as the SiO 2 substrate). CeO 2 can chemically react with the hydroxyl groups on the surface of the material to be polished, weakening the SiO 2The binding force between surface atoms makes it easier to be removed by abrasives. In the present invention, the abrasive particles can be selected from sol cerium dioxide or sintered cerium dioxide.

[0044] In the present invention, the total solid content of cerium dioxide abrasive particles in the slurry composition is 0.05 - 30 wt%, preferably the solid content is 0.05 - 10 wt%, more preferably the solid content is 0.05 wt% - 5 wt%; in the examples of the present invention, the slurry composition may contain about 0.05 wt% of cerium dioxide or about 0.05 - 0.5 wt%, 0.5 - 1 wt%, 1 - 2 wt%, 2 - 3 wt%, 3 - 4 wt%, 4 - 5 wt%, 5 - 6 wt%, 6 - 7 wt%, 7 - 8 wt%, 8 - 9 wt%, 9 - 10 wt% of cerium dioxide, or may also contain more than 10 wt% but not more than 30 wt% of cerium dioxide.

[0045] In the present invention, the average particle size range of cerium dioxide abrasive particles is 10 nm - 500 nm, preferably the average particle size range is 50 nm - 300 nm, more preferably the average particle size range is between 50 nm - 200 nm. Specifically, the average particle size of the cerium dioxide abrasive in the present invention can be about 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 250 nm, 300 nm, 400 nm, 500 nm or any range between two of the above average particle sizes. When the particle size of the abrasive grains is too small, the polishing speed decreases, resulting in low efficiency in terms of productivity; when the particle size is too large, it will have an adverse effect on the dispersibility, the distribution uniformity is relatively poor, and agglomeration is likely to occur, which will cause the removal rates of different regions on the material surface to be inconsistent, resulting in a decrease in the surface flatness after polishing; due to its strong mechanical action, large particle size abrasives may also have a certain removal effect on the material that does not need to be removed, thereby reducing the selectivity of polishing. The average particle size of cerium dioxide can be measured using any suitable technique. In the present invention, the average particle size of the abrasive grains is measured by dynamic light scattering DLS technology.

[0046] <Electrolyte modifier>,

[0047] The electrolyte modifier is an organic polymer containing a carboxylic acid group or carboxylate, carboxylic acid ester, and the electrolyte modifier has the following general molecular structure:

[0048]

[0049] Where R 1 is selected from H, Na, K, alkyl or NH 4 ; R2 Selected from H or an alkyl group, preferably a C1-C6 alkyl group; n represents the number of repeating monomer units, and the value range of n is not fixed and varies according to the molecular weight of the repeating unit. The value range of n makes the molecular weight of the polymer range between 500 and 500,000, preferably 500-10,000, more preferably 500-3,000, and even more preferably 1,000-2,000. The alkyl group is preferably a C1-C6 alkyl group, such as methyl, ethyl, propyl, isopropyl, butyl and other common alkyl substituents in the art.

[0050] In the present invention, the cerium dioxide abrasive grains have a positive charge on the surface. After being coated with an electrolyte modifier, the surface charge changes from positive to negative. During the CMP polishing process, the negatively charged polyelectrolyte adsorbs on the silicon nitride surface, inhibiting the polishing of silicon nitride and ensuring a high selectivity ratio of silicon oxide / silicon nitride.

[0051] In the embodiments of the present invention, the structures that the electrolyte modifier can select include one or a combination of several of polyacrylate, polyacrylic acid, ammonium polyacrylate, potassium polyacrylate, polymethacrylate, polymethacrylic acid, ammonium polymethacrylate, potassium polymethacrylate, etc.

[0052] In the embodiments of the present invention, the mass content of the electrolyte modifier in the slurry composition is 0.1-0.3 wt%, specifically it can be 0.09 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, etc., or within the range between any two of the above contents.

[0053] <Nitrogen-containing chemical additive>

[0054] In the present invention, the nitrogen-containing chemical additive has an electrostatic adsorption effect with negatively charged silicon dioxide. Thus, when polishing a patterned wafer, the nitrogen-containing chemical additive is more likely to adsorb in the recessed area, inhibiting the further polishing of silicon oxide in the groove, thereby providing better planarization efficiency and dishing defects. The detailed mechanism is as Figure 1 shown.

[0055] In the present invention, the nitrogen-containing chemical additive is selected from at least one of hydroxamic acid compounds, polyethyleneimine, branched polyethyleneimine or polyvinylamine, etc.; preferably, the nitrogen-containing chemical additive is selected from at least one of polyethyleneimine, branched polyethyleneimine or polyvinylamine, and more preferably at least one of polyethyleneimine and branched polyethyleneimine.

[0056] Specifically, the hydroxamic acid compounds of the present invention are selected from one or a combination of benzyl hydroxamic acid, acetyl hydroxamic acid, isohydroxamic acid, and salicylhydroxamic acid; the branched polyethyleneimine is selected from polyether-branched polyethyleneimine, and the polyether is selected from at least one of polyethylene oxide, polypropylene oxide, and polyethylene oxide-polypropylene oxide copolymer.

[0057] In the present invention, the structural formula of polyvinylamine is The structural formula of polyethyleneimine is In the present invention, the polyether-branched polyethyleneimine is a copolymer of polyethyleneimine and polyethylene oxide and / or polypropylene oxide.

[0058] Furthermore, in the present invention, the molecular weight of the polyethyleneimine and the branched polyethyleneimine polymer is selected from 600 to 100,000, and more preferably the molecular weight is 800 to 50,000; the polyvinylamine polymer is selected from polyvinylamine with a molecular weight of 600 to 100,000, and preferably polyvinylamine with a molecular weight of 1,000 to 20,000;

[0059] In the examples of the present invention, the mass content of the nitrogen-containing chemical additive in the slurry composition is 0.03 to 0.5 wt%. Specifically, it can be 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt% of the nitrogen-containing chemical additive.

[0060] In the examples of the present invention, the mass ratio of the nitrogen-containing chemical additive to the electrolyte modifier is 1:0.5 to 1:3; the present invention has found through research that when the mass ratio of the nitrogen-containing chemical additive to the electrolyte modifier is controlled within the above range, the polishing effect becomes better as the amount of the nitrogen-containing chemical additive increases. Specifically, the mass ratio of the nitrogen-containing chemical additive to the electrolyte modifier can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.2, 1:1.5, 1:2, 1:2.5, 1:3, etc.

[0061] <pH regulator>

[0062] The change in pH value will affect the potential on the surface of abrasive grains, thereby changing the dispersion state and surface activity of abrasive grains in the polishing liquid. The change in the surface properties of abrasive grains will also affect their interaction with the surface of the material to be polished, and further affect the polishing efficiency and quality. In order to make the electrolyte modifier and the nitrogen-containing chemical additive have a better adsorption effect, the pH of the slurry composition is regulated by a pH regulator in the present invention. In the examples of the present invention, the pH of the slurry composition is preferably 4-9, more preferably 4.5-7. For example, it can be in the ranges of 4.5-5, 5-5.2, 5.2-6, 6-6.4, 6.4-7, 7-7.4, 7.4-8, 8-9, etc. or a specific pH value therein. The pH regulator is selected from at least one of hydrochloric acid, phosphoric acid, acetic acid, propionic acid, citric acid, malonic acid, sulfonic acid, hydroxyethylsulfonic acid, aromatic carboxylic acid, and heteroaromatic carboxylic acid. The aromatic carboxylic acid can be selected from at least one of benzoic acid, 1,2-phthalic acid, 1,3-phthalic acid, 1,4-phthalic acid, salicylic acid, etc.; the heteroaromatic carboxylic acid is selected from at least one of picolinic acid, pyridinedicarboxylic acid, etc.;

[0063] <Biocide>

[0064] The main function of the biocide is to inhibit or kill microorganisms in the slurry to prevent the slurry from deteriorating and its performance from declining. In the present invention, the content of the biocide is 0.001% to 0.01%, and the biocide is selected from common biocides in the art such as methylisothiazolinone, 5-chloro-2-methyl-4-isothiazolin-3-one, benzisothiazolinone, etc.

[0065] <Groove loss and step height>

[0066] In the present invention, the groove loss is measured by an ellipsometer of model nano specⅡ; the step height is measured by a step profiler, and its model is KLA probe-type profiler Tencor TM P-17 stylus Profiler.

[0067] The step height is the height of the dielectric material of the raised area relative to the height of the dielectric material at the adjacent groove. Before polishing, there is a certain step height on the wafer surface, that is, the height difference between the groove area and the surrounding planar area. During the polishing process, the material removal rates of the planar area and the groove area are different. Generally speaking, the material removal rate of the planar area is relatively high because the contact between the polishing pad and the planar area is more sufficient, and the flow and chemical reaction of the polishing liquid are more uniform. As the polishing progresses, the step height gradually decreases. In STI, the step height affects the electrical insulation performance between different circuits in the chip. A larger step height may cause problems such as electrical short circuit or leakage.

[0068] Groove loss refers to the amount of oxide layer material in the shallow groove that is over-removed during the CMP process of STI. Groove loss will reduce the depth of the shallow groove, affect the isolation effect, cause problems such as possible leakage between adjacent devices, and reduce the performance and reliability of integrated circuits.

[0069] Example

[0070] The following examples further illustrate the present invention, but of course should not be construed as limiting the scope of the present invention in any form.

[0071] Hereinafter, the specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments including the following examples and can be variously modified within the scope that can achieve the object of the invention and does not exceed the gist of the invention.

[0072] In the following examples, unless otherwise specifically stated, the raw material reagents or processing techniques used are common commercially available raw materials or conventional processing techniques in the art.

[0073] In Examples 1-6 and Comparative Examples 1-6, cerium oxide abrasive particles with an average particle size of 100 nm were used as the abrasive particles, polyacrylic acid PAA with a molecular weight of 1000-2000 was selected as the electrolyte modifier, hydrochloric acid was used as the pH regulator, and methylisothiazolinone with a content of 0.001 wt% was used as the biocide;

[0074] In Example 7, cerium oxide abrasive particles with an average particle size of 200 nm were used, polyacrylic acid PAA with a molecular weight of 1000-2000 was selected as the electrolyte modifier, hydrochloric acid was used as the pH regulator, and methylisothiazolinone with a content of 0.001 wt% was used as the biocide;

[0075] In Example 8, cerium oxide abrasive particles with an average particle size of 300 nm were used, polyacrylic acid PAA with a molecular weight of 1000-2000 was selected as the electrolyte modifier, hydrochloric acid was used as the pH regulator, and methylisothiazolinone with a content of 0.001 wt% was used as the biocide;

[0076] In Example 9, cerium oxide abrasive particles with an average particle size of 50 nm were used, polymethyl methacrylate PMMA with a molecular weight of 1000-2000 was selected as the electrolyte modifier, hydrochloric acid was used as the pH regulator, and methylisothiazolinone with a content of 0.001 wt% was used as the biocide;

[0077] In Example 10, cerium oxide abrasive particles with an average particle size of 100 nm were used, polyacrylic acid PAA with a molecular weight of 4000-5000 was selected as the electrolyte modifier, hydrochloric acid was used as the pH regulator, and methylisothiazolinone with a content of 0.001 wt% was used as the biocide;

[0078] Example 1

[0079] Prepare an STI polishing composition using cerium oxide polishing particles with an average particle size of 100 nm and a content of 0.5 wt%, 0.15 wt% of the electrolyte modifier PAA, 0.05 wt% of the nitrogen-containing chemical additive polyethyleneimine (BASF PN40, molecular structure is ), 0.001 wt% of a biocide, and deionized water, and adjust the pH to around 5.2 using a pH regulator.

[0080] For the preparation methods of the slurry compositions of Examples 2 - 10 and Comparative Examples 1 - 6, refer to Example 1. The content of each component, the type selected, and the pH control of the slurry composition are as listed in Table 1, thereby preparing different polishing slurry compositions.

[0081] Table 1 Slurry Compositions of Examples 1 - 10 and Comparative Examples 1 - 6

[0082]

[0083] Example 2

[0084] Prepare an STI polishing composition using cerium oxide polishing particles with an average particle size of 100 nm and a content of 0.5 wt%, 0.15 wt% of the electrolyte modifier PAA, 0.05 wt% of the nitrogen-containing chemical additive polyvinylamine, 0.001 wt% of a biocide, and deionized water, and adjust the pH to around 5.2 using a pH regulator.

[0085] Example 3

[0086] Prepare an STI polishing composition using cerium oxide polishing particles with an average particle size of 100 nm and a content of 0.5 wt%, 0.15 wt% of the electrolyte modifier PAA, 0.05 wt% of the nitrogen-containing chemical additive benzohydroxamic acid, 0.001 wt% of a biocide, and deionized water, and adjust the pH to around 5.2 using a pH regulator.

[0087] Example 4

[0088] Prepare an STI polishing composition using cerium oxide polishing particles with an average particle size of 100 nm and a content of 0.5 wt%, 0.3 wt% of the electrolyte modifier PAA, 0.5 wt% of the nitrogen-containing chemical additive polyvinylamine, 0.001 wt% of a biocide, and deionized water, and adjust the pH to around 5.2 using a pH regulator.

[0089] Example 5

[0090] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, 0.09 wt% of an electrolyte modifier PAA, 0.03 wt% of a nitrogen-containing chemical additive BASF PN40, 0.001 wt% of a biocide, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0091] Example 6

[0092] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, 0.3 wt% of an electrolyte modifier PAA, 0.2 wt% of a nitrogen-containing chemical additive benzylhydroxamic acid, 0.001 wt% of a biocide, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0093] Example 7

[0094] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 200 nm at a content of 5 wt%, 0.2 wt% of an electrolyte modifier PAA, 0.4 wt% of a nitrogen-containing chemical additive BASF PN40, 0.001 wt% of a biocide, and deionized water, and adjusted to around 7.4 using a pH regulator.

[0095] Example 8

[0096] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 300 nm at a content of 2 wt%, 0.2 wt% of an electrolyte modifier PAA, 0.4 wt% of a nitrogen-containing chemical additive BASF PN40, 0.001 wt% of a biocide, and deionized water, and adjusted to around 6 using a pH regulator.

[0097] Example 9

[0098] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 50 nm at a content of 2.5 wt%, 0.2 wt% of an electrolyte modifier PMMA, 0.4 wt% of a nitrogen-containing chemical additive BASF PN40, 0.001 wt% of a biocide, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0099] Example 10

[0100] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, 0.2 wt% of an electrolyte modifier PAA, 0.4 wt% of a nitrogen-containing chemical additive BASF PN40, 0.001 wt% of a biocide, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0101] Comparative Example 1

[0102] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, an electrolyte modifier PAA at 0.15 wt%, a biocide at 0.001 wt%, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0103] Comparative Example 2

[0104] An STI polishing composition was prepared using silica polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, an electrolyte modifier PAA at 0.15 wt%, a nitrogen-containing chemical additive BASF PN40 at 0.05 wt%, a biocide at 0.001 wt%, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0105] Comparative Example 3

[0106] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, an electrolyte modifier PAA at 0.2 wt%, a nitrogen-containing chemical additive BASF PN40 at 0.04 wt%, a biocide at 0.001 wt%, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0107] Comparative Example 4

[0108] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, an electrolyte modifier PAA at 0.05 wt%, a nitrogen-containing chemical additive BASF PN40 at 0.5 wt%, a biocide at 0.001 wt%, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0109] Comparative Example 5

[0110] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, a nitrogen-containing chemical additive BASF PN40 at 0.05 wt%, a biocide at 0.001 wt%, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0111] Comparative Example 6

[0112] An STI polishing composition was prepared using cerium oxide polishing particles with an average particle size of 100 nm at a content of 0.5 wt%, an electrolyte modifier PAA at 0.15 wt%, a nitrogen-containing chemical additive polyvinylpyrrolidone at 0.05 wt%, a biocide at 0.001 wt%, and deionized water, and adjusted to around 5.2 using a pH regulator.

[0113] The slurries in the examples and comparative examples of the present invention were characterized by the following test methods:

[0114] Using an IC1000 polishing pad (Rohm and Haas Electronic Materials CMP), a 300mm STI 7.5k TEOS patterned wafer was polished to measure the trench loss and step height change at a 100*100μm pitch.

[0115] Polishing process parameters: down pressure 3psi, platen (14 inches in diameter) rotation speed 70rpm, polishing head rotation speed 80rpm, polishing slurry flow rate 200ml / min.

[0116] Table 2: Trench loss and step height change in each example and comparative example

[0117]

[0118]

[0119] As shown in Table 2, the aqueous slurry composition contains both a nitrogen-containing chemical additive and an electrolyte modifier, which can effectively reduce trench loss under the same conditions, while showing controllable step height removal and demonstrating good planarization efficiency. The results show that polyvinylamine, polyethyleneimine, and hydroxamic acid as nitrogen-containing additives have better effects on controlling trench loss and step height compared to polyvinylpyrrolidone, especially when polyethyleneimine-based polymers are used as nitrogen-containing additives. From Comparative Examples 1 and 5, it can be found that only when the nitrogen-containing additive and the electrolyte modifier act together can the polishing uniformity and planarization in the STI process be achieved. In Comparative Example 5, there is only a nitrogen-containing chemical additive without an electrolyte modifier. Although the planarization effect is not greatly affected, the trench loss is serious, indicating that without the electrolyte modifier, it cannot be adsorbed on the silicon nitride surface to inhibit SiN polishing, so there is an over-polishing phenomenon, resulting in trench loss; in Comparative Example 1, there is no nitrogen-containing chemical additive. Although the electrolyte modifier can inhibit SiN polishing, it cannot protect the silicon oxide in the groove. Under the action of the abrasive particles in the polishing solution, the silicon oxide in the groove will also be removed, the step height is large, and the polishing uniformity is poor, and effective planarization cannot be achieved. In this case, due to the loss of the protection effect on the silicon oxide in the groove, even if there is still unremoved silicon oxide on the SiN layer, the silicon oxide in the groove will be continuously removed, ultimately resulting in serious trench loss. In the present invention, cerium oxide abrasive acts together with the nitrogen-containing chemical additive and the electrolyte modifier to achieve a good polishing effect. In Comparative Example 2, due to the use of silica abrasive, even if the electrolyte modifier and the nitrogen-containing chemical additive are used, it cannot play a role in protecting the silicon oxide in the groove, and a large step height will still be generated; at the same time, due to the inability to obtain the polishing end point (EDP) and the inability to achieve self-stopping, serious trench loss is caused. The results of Comparative Examples 3 and 4 show that the dosages of the nitrogen-containing chemical additive and the electrolyte modifier need to be controlled within a reasonable range to achieve smaller trench loss, show better polishing effect, be beneficial to good planarization efficiency and low defect rate, and ensure the normal operation of semiconductor devices.

Claims

1. A chemical mechanical polishing aqueous slurry composition for polishing semiconductor devices, characterized in that: The composition comprises cerium dioxide abrasive, an electrolyte modifier, a nitrogen-containing chemical additive, a pH regulator, and a biocide; the pH of the composition is 4-9; the mass ratio of the nitrogen-containing chemical additive to the electrolyte modifier is 1:0.5-1:3; the nitrogen-containing chemical additive is selected from hydroxamic acid compounds, polyethyleneimine, branched polyethyleneimine or polyethyleneamine.

2. The slurry composition according to claim 1, characterized in that: The mass fraction of the nitrogen-containing chemical additive in the slurry composition is 0.03% to 0.5%; the mass fraction of the electrolyte modifier in the slurry composition is 0.1% to 0.3%.

3. The slurry composition according to any one of claims 1 to 2, characterized in that: The hydroxamic acid compound is selected from one or a combination of benzylhydroxamic acid, acetohydroxamic acid, isohydroxamic acid, and salicylic hydroxamic acid; the branched polyethyleneimine is selected from polyether branched polyethyleneimine, and the polyether is selected from at least one of polyoxyethylene, polyoxypropylene, and polyoxyethylene-polyoxypropylene copolymer.

4. The slurry composition according to any one of claims 1 to 3, characterized in that: The electrolyte modifier has the following molecular structure: Wherein R1 is selected from H, alkyl, Na, K or NH4; R2 is selected from H or alkyl; and the molecular weight range of the electrolyte modifier is selected from 500-3000.

5. The slurry composition according to claim 4, characterized in that: The electrolyte modifier is selected from one or a combination of polyacrylate, polyacrylic acid, polyacrylic acid ammonium salt, polyacrylic acid potassium salt, polymethacrylate, polymethacrylic acid, polymethacrylic acid ammonium salt, and polymethacrylic acid potassium salt.

6. The slurry composition according to any one of claims 1 to 5, characterized in that: The pH regulator is selected from at least one of hydrochloric acid, phosphoric acid, acetic acid, propionic acid, citric acid, malonic acid, sulfonic acid, isethionic acid, aromatic carboxylic acid, and aromatic heterocarboxylic acid; and / or, the biocide is selected from one or a combination of methylisothiazolinone, 5-chloro-2-methyl-4-isothiazolin-3-one, and benzisothiazolinone.

7. The slurry composition according to any one of claims 1 to 6, characterized in that: The mass fraction of the total solid of the cerium dioxide grinding particles is 0.05%-5%; and / or the mass fraction of the biocide is 0.001%~0.01%.

8. The slurry composition according to any one of claims 1 to 7, characterized in that: The average particle size of the cerium dioxide abrasive particles is in the range of 10 nm to 500 nm, preferably in the range of 50 nm to 300 nm, and more preferably in the range of 50 nm to 200 nm.

9. Use of the aqueous slurry composition according to any one of claims 1 to 8 in the manufacture of semiconductor devices.

10. A method for polishing a semiconductor device wafer, characterized in that: The slurry composition according to any one of claims 1 to 8 is brought into contact with a wafer for polishing.

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