A chemical mechanical polishing liquid and its preparation method and application

Abstract

The present invention discloses a chemical mechanical polishing liquid, including a grinding retarder, wherein the molecular structure of the grinding retarder is: , wherein R is a branched alkyl group with a carbon number of 3 to 18; X is one of a hydroxide ion, a chloride ion, a bromide ion or an iodide ion; and n is 1 or 2. The present invention also discloses a preparation method and application of a chemical mechanical polishing liquid. The present invention provides a chemical mechanical polishing liquid and a preparation method and application thereof. By adjusting the amount of an accelerator and a grinding retarder, a polishing liquid with a suitable polysilicon / silicon dioxide selectivity ratio can be obtained, and a high flatness can be achieved through one-step polishing without polysilicon residue.

Description

Technical Field

[0001] The invention relates to the technical field of polishing liquid, and in particular to a chemical mechanical polishing liquid and a preparation method and application thereof. Background Art

[0002] In integrated circuit manufacturing, as the technology nodes continue to shrink, the complexity of the interconnect structure has increased significantly, and multi-layer deposition processes have become the norm, which directly leads to extreme irregularities in the surface morphology of the substrate. Chemical mechanical polishing is usually used in the prior art to achieve a high degree of flatness on the surface of a silicon wafer. The chemical mechanical polishing process is to use a mixture containing an abrasive and a polishing pad to polish a silicon wafer surface. In a typical chemical mechanical polishing method, the substrate is directly contacted with a rotating polishing pad, and a load is used to apply pressure to the back of the substrate. During polishing, the pad and the operating table rotate while maintaining a downward force on the back of the substrate, and a polishing liquid or polishing slurry is applied to the pad, and the polishing liquid chemically reacts with the film being polished to start the polishing process.

[0003] However, in a multi-layer structure where polysilicon and silicon dioxide coexist, the CMP process faces two major problems: First, the high polishing rate selectivity between polysilicon and silicon dioxide makes it inevitable that there will be dishing of polysilicon when the final polishing process stops on the silicon dioxide layer; second, during the chemical mechanical polishing of shallow trench isolation (STI), dishing forms on the silicon dioxide surface, causing polysilicon to remain in the silicon dioxide dishing during the subsequent polishing process after covering the polysilicon layer.

[0004] In view of these problems, US2003 / 0153189A1 discloses a chemical mechanical polishing liquid and method for polishing polysilicon, wherein the polishing liquid comprises a polymer surfactant and a grinding particle selected from aluminum oxide and cerium oxide, wherein the polymer surfactant is a polycarboxylate surfactant, and the slurry can make the polishing rate of a large area on the surface of polysilicon much higher than the polishing rate in the groove, thereby reducing the depression. US2003 / 0216003A1 and US2004 / 0163324A1 disclose a method for manufacturing FLAS. The method includes a polishing liquid for polishing polysilicon, wherein the polishing liquid comprises at least one compound containing -N(OH), -NH(OH), -NH2(OH) groups, and the polishing selectivity ratio of polysilicon to silicon dioxide using the slurry is greater than 50. US2004 / 0123528A1 discloses an acidic polishing liquid comprising abrasive particles and an anionic compound, wherein the anionic compound can reduce the removal rate of the protective layer film and improve the removal rate selectivity ratio of polysilicon to the protective layer film. US2005 / 0130428A1 and CN1637102A disclose a slurry for chemical mechanical polishing of polysilicon, the slurry composition includes one or more non-ionic surfactants that form a passivation layer on the polysilicon layer and a second surfactant that can form a second passivation layer to reduce the removal rate of silicon nitride or silicon oxide. Patent document US6191039 discloses a chemical mechanical polishing method that can reduce the time and cost of chemical polishing and has a good flattening effect.

[0005] However, although the above technologies have achieved a certain flattening effect to a certain extent and shortened the polishing time and cost, they are either operated in two steps or simply suppress the polishing rate of polysilicon, which is not conducive to the removal of polysilicon in the silicon dioxide butterfly depression. In addition, the operation is complicated and the polishing effect is limited. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a chemical mechanical polishing liquid, a preparation method and an application thereof. By adjusting the amount of accelerator and grinding retarder, a polishing liquid with a suitable polysilicon / silicon dioxide selectivity ratio can be obtained, and a high degree of flattening can be achieved through one-step polishing without polysilicon residue.

[0007] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0008] A chemical mechanical polishing liquid includes a grinding retarder, wherein the molecular structure of the grinding retarder is: , wherein R is a branched alkyl group having 3 to 18 carbon atoms; X is one of hydroxide ion, chloride ion, bromide ion or iodide ion; and n is 1 or 2.

[0009] According to one aspect of the present invention, R is a branched alkyl group having 3 to 18 carbon atoms, and preferably, R is a branched alkyl group having 3 to 8 carbon atoms.

[0010] According to one aspect of the present invention, abrasive particles and a speed increasing agent are also included.

[0011] According to one aspect of the present invention, the mass percentage of the grinding retarder is 0.005%-1%.

[0012] According to one aspect of the present invention, the mass percentage of the speed increasing agent is 0.001%-1%.

[0013] According to one aspect of the present invention, the mass percentage of the abrasive particles is 1%-5%.

[0014] According to one aspect of the present invention, the grinding retardant includes but is not limited to the following optical isomers and mixtures thereof: R, R configuration, S, S configuration, R, S configuration and / or S, R configuration.

[0015] According to one aspect of the present invention, the speed increasing agent is a compound containing a guanidine group.

[0016] According to one aspect of the present invention, the compound containing a guanidine group is a monoguanidine, a biguanidine, a polyguanidine compound and an acid addition salt thereof. The monoguanidine or its acid addition salt is one or more of guanidine, guanidine carbonate, guanidine acetate, biguanidine hydrogen phosphate, guanidine hydrochloride, guanidine nitrate, guanidine sulfate, aminoguanidine, aminoguanidine bicarbonate, aminoguanidine sulfonate, aminoguanidine nitrate and / or aminoguanidine hydrochloride.

[0017] According to one aspect of the present invention, the biguanide or its acid addition salt is biguanide, metformin, phenformin, 1,1'-hexylbis[5-(p-chlorophenyl)biguanide, morpholineguanidine, acid addition salts of the above compounds and / or 6-amidino-2-naphthyl-4-guanidinobenzoate methylsulfonate; the acid is hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid and / or sulfonic acid.

[0018] According to one aspect of the present invention, the polyguanidine or its acid addition salt is polyhexamethyleneguanidine, polyhexamethylenebiguanidine, poly(hexamethylenebiscyanoguanidine-hexamethylenediamine) and / or its acid addition salt; the acid is hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid and / or sulfonic acid; the degree of polymerization of the polyguanidine compound or its acid addition salt is 2 to 100.

[0019] According to one aspect of the present invention, the abrasive particles are one or more of silicon dioxide, aluminum oxide, cerium dioxide, titanium dioxide and polymer abrasive particles. The particle size of the abrasive particles is preferably 20 to 150 nm, more preferably 30 to 120 nm.

[0020] According to one aspect of the present invention, the chemical mechanical polishing liquid further comprises a pH regulator, a viscosity regulator and / or a defoaming agent. The pH value of the polishing liquid is 7-12.

[0021] According to one aspect of the present invention, the method for preparing the chemical mechanical polishing solution comprises the following steps:

[0022] Configure the required components;

[0023] Mix all ingredients well.

[0024] According to one aspect of the present invention, the chemical mechanical polishing liquid is used in the polishing process of single crystal silicon and polycrystalline silicon.

[0025] Advantages of the present invention: The grinding retarder in the chemical mechanical polishing liquid can significantly reduce the removal rate of polysilicon without reducing the removal rate of silicon dioxide, thereby significantly reducing the selectivity of polysilicon to silicon dioxide; the accelerator can dissolve polysilicon and take away the polishing residue to avoid re-adsorption on the wafer or polishing pad. By adjusting the amount of the accelerator and the grinding retarder, a polishing liquid with a suitable polysilicon / silicon dioxide selectivity can be obtained, and monocrystalline silicon and polysilicon films can be well polished under alkaline conditions. Compared with the prior art, this polishing liquid better solves the problems of the occurrence of polysilicon dish-shaped depressions in the silicon dioxide channel and the polysilicon residue in the silicon dioxide dish-shaped depressions during the prior polysilicon polishing process, and can achieve high flatness through one-step polishing without polysilicon residue. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] A chemical mechanical polishing liquid comprises abrasive particles, an accelerating agent, and a grinding retarder, wherein the molecular structure of the grinding retarder is: , wherein R is a branched alkyl group having 3 to 18 carbon atoms; X is one of hydroxide ion, chloride ion, bromide ion or iodide ion; and n is 1 or 2.

[0028] In practical applications, R is a branched alkyl group with a carbon number of 3 to 18. Preferably, R is a branched alkyl group with a carbon number of 3 to 8, such as the grinding retarder can be 1,1,1',1'-tetraisopropyl-(2,2'-bipyrrol)-1,1'-ammonium bromide, 1,1,1',1'-tetraisopropyl-(2,2'-bipyrrol)-1,1'-ammonium iodide, 1,1,1',1'-tetraisobutyl-(2,2'-bipyrrol)-1,1'-ammonium bromide, 1,1,1',1'-tetraisobutyl-(2,2'-bipyrrol)-1,1'-ammonium bromide, 1,1,1',1'-tetraisobutyl-(2,2'-bipyrrol)-1,1'-ammonium bromide, 1,1,1',1'-tetrasec-butyl-(2,2 '-Bis(2,2'-piperidinyl)-1,1'-ammonium bromide, 1,1,1',1'-tetraisopropyl-(2,2'-bipiperidinyl)-1,1'-ammonium bromide, 1,1,1',1'-tetraisopropyl-(2,2'-bipiperidinyl)-1,1'-ammonium iodide, 1,1,1',1'-tetraisobutyl-(2,2'-bipiperidinyl)-1,1'-ammonium bromide, 1,1,1',1'-tetraisobutyl-(2,2'-bipiperidinyl)-1,1'-ammonium bromide, 1,1,1',1'-tetra-sec-butyl-(2,2'-bipiperidinyl)-1,1'-ammonium bromide.

[0029] In practical applications, the grinding retardant includes but is not limited to the following optical isomers and mixtures thereof: R, R configuration, S, S configuration, R, S configuration and / or S, R configuration.

[0030] In practical applications, the mass percentage of the abrasive particles is 1%-5%, the mass percentage of the speed accelerator is 0.001%-1%, and the mass percentage of the grinding retarder is 0.001%-0.1%.

[0031] In practical applications, the grinding retarder in the chemical mechanical polishing liquid can significantly reduce the removal rate of polysilicon without reducing the removal rate of silicon dioxide, thereby significantly reducing the selectivity of polysilicon to silicon dioxide; the accelerator can dissolve polysilicon and take away the polishing residue to avoid re-adsorption on the wafer or polishing pad. By adjusting the amount of the accelerator and the grinding retarder, a polishing liquid with a suitable polysilicon / silicon dioxide selectivity can be obtained, and monocrystalline silicon and polysilicon films can be well polished under alkaline conditions. This polishing liquid can better solve the problem of the occurrence of polysilicon dish-shaped depressions in the silicon dioxide channel and the polysilicon residue in the silicon dioxide dish-shaped depression during the polysilicon polishing process, and can achieve high flatness through one-step polishing without polysilicon residue.

[0032] In practical applications, the speed increasing agent is a compound containing a guanidine group. Specifically, the compound containing a guanidine group is a monoguanidine, biguanidine, polyguanidine compound and an acid addition salt thereof.

[0033] In practical applications, the monoguanidine compound and its acid addition salt are one or more of guanidine, guanidine carbonate, guanidine acetate, biguanidine phosphate, guanidine hydrochloride, guanidine nitrate, guanidine sulfate, aminoguanidine, aminoguanidine bicarbonate, aminoguanidine sulfonate, aminoguanidine nitrate and aminoguanidine hydrochloride.

[0034] In practical applications, the biguanide compound or its acid addition salt is biguanide, metformin, phenformin, 1,1'-hexylbis[5-(p-chlorophenyl)biguanide, morpholineguanidine, acid addition salts of the above compounds and / or 6-amidino-2-naphthyl-4-guanidinobenzoate methylsulfonate; the acid is hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid and / or sulfonic acid.

[0035] In practical applications, the polyguanidine or its acid addition salt is polyhexamethyleneguanidine, polyhexamethylenebiguanidine, poly(hexamethylenebiscyanoguanidine-hexamethylenediamine) and / or its acid addition salt; the acid is hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid and / or sulfonic acid; the degree of polymerization of the polyguanidine compound or its acid addition salt is 2 to 100.

[0036] In practical applications, the abrasive particles are one or more of silicon dioxide, aluminum oxide, cerium dioxide, titanium dioxide and polymer abrasive particles. Preferably, the particle size of the abrasive particles is preferably 20 to 150 nm, more preferably 30 to 120 nm.

[0037] In practical applications, the pH value of the polishing liquid is preferably 7 to 12. The pH of the polishing liquid is controlled by the pH adjuster. The pH adjuster is an inorganic acid, an organic acid, an alkali solution or a combination thereof. Specifically, the inorganic acid can be nitric acid, hydrochloric acid, sulfuric acid and / or phosphoric acid. Alternatively, the alkali solution is an inorganic base, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide and / or ammonia water.

[0038] In practical applications, the chemical mechanical polishing liquid further includes a viscosity regulator and / or a defoamer. Specifically, the viscosity regulator and the defoamer can be selected from conventional viscosity regulator and defoamer products on the market.

[0039] In practical applications, the preparation method of the chemical mechanical polishing liquid comprises the following steps:

[0040] Configure the required components;

[0041] Mix all ingredients well.

[0042] In practical applications, the chemical mechanical polishing liquid is used in the polishing process of single crystal silicon and polycrystalline silicon.

[0043] The advantages of the present invention are further described below through more specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0044] Table 1 shows the formulas of Examples 1 to 19 and Comparative Examples 1 to 6 of the chemical mechanical polishing solution of the present invention. The polishing solution can be obtained by uniformly mixing the components and their contents given in the table, supplementing the mass percentage with water to 100%, and adjusting the pH value to the required value with ammonia water or nitric acid.

[0045] Table 1

[0046] In order to verify the use effect of the chemical mechanical polishing liquid of the invention, effect verification example 1 is set up for illustration.

[0047] Effect verification example 1:

[0048] The polishing liquids of Comparative Examples 1-6 and the polishing liquids of Examples 17-19 of the present invention were used to perform polishing experiments on polycrystalline silicon and silicon dioxide (Teos), and the polishing conditions were as follows: the polishing machine was Logitech PM5 Polisher, 12-inch politex polishing pad (black fine polishing damping cloth), 4 cm*4 cm square wafer, grinding pressure was 3 psi, grinding table speed was 70 rpm, grinding head rotation speed was 150 rpm, and polishing liquid drop acceleration was 100 mL / min. The removal rate values ​​of each polishing liquid for polycrystalline silicon and silicon dioxide were measured respectively, and the selectivity ratio of polycrystalline silicon to silicon dioxide was calculated at the same time, and Table 2 was obtained.

[0049] Table 2

[0050] As shown in Table 2, compared with Comparative Examples 1 to 3 without adding a grinding retarder, Examples 17 to 19 added a grinding retarder, which significantly reduced the removal rate of polysilicon and had little effect on the removal rate of silicon dioxide, thereby reducing the selectivity of polysilicon to silicon dioxide. Compared with Comparative Examples 4 to 6 without adding a accelerator, the examples added an accelerator. When other components and their contents were the same, the addition of guanidine compounds significantly increased the removal rate of polysilicon. Therefore, the content of grinding retarder and guanidine compounds can be used to adjust the polysilicon / silicon dioxide selectivity of the polishing liquid.

[0051] Advantages of the present invention: The grinding retarder in the chemical mechanical polishing liquid can significantly reduce the removal rate of polysilicon without reducing the removal rate of silicon dioxide, thereby significantly reducing the selectivity of polysilicon to silicon dioxide; the accelerator can dissolve polysilicon and take away the polishing residue to avoid re-adsorption on the wafer or polishing pad. By adjusting the amount of the accelerator and the grinding retarder, a polishing liquid with a suitable polysilicon / silicon dioxide selectivity can be obtained, and monocrystalline silicon and polysilicon films can be well polished under alkaline conditions. Compared with the prior art, this polishing liquid better solves the problems of the occurrence of polysilicon dish-shaped depressions in the silicon dioxide channel and the polysilicon residue in the silicon dioxide dish-shaped depressions during the prior polysilicon polishing process, and can achieve high flatness through one-step polishing without polysilicon residue.

[0052] The above is only the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A chemical mechanical polishing liquid, characterized in that: It includes a grinding retarder, abrasive particles and an accelerating agent, wherein the mass percentage of the grinding retarder is 0.005%-1%, the mass percentage of the accelerating agent is 0.001%-1%, and the molecular structure of the grinding retarder is: , wherein R is a branched alkyl group having 3 to 8 carbon atoms; X is one of a hydroxide ion, a chloride ion, a bromide ion or an iodide ion; n is 1 or 2, and the accelerator is a compound containing a guanidine group.

2. A chemical mechanical polishing solution according to claim 1, characterized in that: The grinding retardant includes, but is not limited to, the following optical isomers and mixtures thereof: R, R configuration, S, S configuration, R, S configuration and / or S, R configuration.

3. A chemical mechanical polishing solution according to claim 1, characterized in that: The mass percentage of the abrasive particles is 1%-5%.

4. A method for preparing a chemical mechanical polishing solution according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Configure the required components; Mix all ingredients well.

5. Use of a chemical mechanical polishing liquid as claimed in any one of claims 1 to 3 in the polishing process of single crystal silicon and polycrystalline silicon.

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