CN115093794B - Polysilicon polishing composition and application thereof - Google Patents
Polysilicon polishing composition and application thereof Download PDFInfo
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- CN115093794B CN115093794B CN202210690202.8A CN202210690202A CN115093794B CN 115093794 B CN115093794 B CN 115093794B CN 202210690202 A CN202210690202 A CN 202210690202A CN 115093794 B CN115093794 B CN 115093794B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09G—POLISHING COMPOSITIONS; SKI WAXES
- C09G1/00—Polishing compositions
- C09G1/02—Polishing compositions containing abrasives or grinding agents
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
- H01L21/321—After treatment
- H01L21/32115—Planarisation
- H01L21/3212—Planarisation by chemical mechanical polishing [CMP]
Abstract
The invention discloses a polysilicon polishing composition and application thereof, wherein the polysilicon polishing composition takes nano silicon dioxide colloid as a main polishing component, and homopiperazine substances and keto acid substances are added as auxiliary agents. The polishing composition provided by the invention is simultaneously added with the homopiperazine substances and the keto acid substances which are respectively used as the rate accelerator and the selectivity inhibitor, is green and low in toxicity, has high removal rate on polysilicon materials, has high selectivity on silicon oxide and silicon nitride, has few polishing defects, and has obvious advantages compared with the prior art.
Description
Technical Field
The invention relates to the technical field of chemical mechanical polishing, in particular to a polysilicon polishing composition and application thereof.
Background
The development of integrated circuits has greatly promoted the speed of human society toward informatization, intelligent, and in this process, the development and application of some key materials play an important role, and polysilicon is one of them. Polycrystalline silicon is a kind of simple substance silicon, crystal face orientations of crystal grains in the polycrystalline silicon are different, conductivity of the polycrystalline silicon is obviously weaker than that of single crystal silicon, and conductivity of the polycrystalline silicon can be greatly influenced by micro doping. In the MOSFET manufacturing process, polysilicon has lower work function than aluminum, and the corresponding threshold voltage is lower, so that a lower power supply voltage operation circuit can be realized, and the polysilicon also has the advantages of high temperature resistance, ion implantation resistance, self-alignment effect and the like, so that the polysilicon is a main gate material in the integrated circuit manufacturing process at present.
The traditional preparation process of the polysilicon gate comprises three main steps of deposition, photoetching and etching, but with the continuous shrinkage of technical nodes, the surface and the side wall of the polysilicon gate prepared by adopting the process can not meet the requirements of subsequent processes. Therefore, when the IC process is developed below 28nm, a new process is required for preparing the polysilicon gate, and the specific steps include: 1) In thermally oxidized SiO 2 Or vapor deposited Si 3 N 4 Etching upwards to form a groove; 2) Vapor depositing a polysilicon layer; 3) Removing redundant polysilicon by CMP; 4) SiO removal with etching solution 2 Or Si (or) 3 N 4 The dielectric layer can form a polysilicon gate with smooth and flat surface and steep side wall, so that the introduction of the CMP technology plays an important role in the process. In the process, CMP (chemical mechanical polishing technology) is to polish the surface of polysilicon by using the polishing solution containing abrasive and polyurethane polishing pad to generate chemical action, mechanical action and combination of the two actions, and the chemical substance reacts with surface polysilicon to form a soft layer in the polishing process, and the soft layer is stripped and removed by the mechanical action of the abrasive and the polishing pad, so that the polishing solution plays an important role in the CMP process.
Because the Mohs hardness of silicon oxide is close to that of polysilicon, and the silicon oxide also has the advantages of fine granularity, small surface damage after polishing, easy cleaning and the like, the silica sol is mainly used as an abrasive of polysilicon polishing liquid in the current industry. In addition, in order to ensure a certain polysilicon removal rate, uniformity of the polished surface and selectivity to the dielectric material, the polysilicon polishing solution is also added with components such as a rate accelerator, a selectivity inhibitor, a surfactant, a rate inhibitor, a pH regulator and the like. However, the main speed accelerator added by the polysilicon polishing solution in the current market is organic ammonium or aliphatic organic amine with high toxicity and strong corrosiveness, and has great safety risk for production and transportation related personnel; meanwhile, related components such as a rate inhibitor, a surfactant and the like are not sufficiently researched, the selectivity among polishing materials is insufficient, the uniformity of a polishing surface is poor, defects such as Dishing, erosion and the like are easy to appear in a large number, and the performance of a device is easy to be adversely affected.
Korean laid-open patent nos. KR100643628B1, KR100660767B1, KR10109466 2B1, and KR101178716B1 propose that the addition of quaternary ammonium bases such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide to a polysilicon polishing composition as a rate accelerator for polishing a polysilicon material can achieve a high polysilicon removal rate while maintaining a relatively low silicon oxide and silicon nitride removal rate, but such materials have serious static corrosion and the control of polishing defects such as Dishing is not ideal. In addition, the quaternary ammonium alkali compound has higher toxicity, stronger corrosiveness and higher safety risk to production personnel, and the cost for treating waste liquid after polishing is higher, so that the method is gradually not suitable for the development trend of environmental protection in the current industry.
The disclosed patent CN103080256B adopts cerium oxide abrasive, and is added with anionic phosphate dispersant and organic amine such as triazole, piperazine and the like, so that high removal rate of silicon oxide and silicon nitride is realized, the removal rate of polysilicon is only tens of angstroms per minute, and the reverse selectivity is obvious. Still other patents mention adding adjuvants to the composition system to change isoelectric points of silicon oxide and silicon nitride by adsorption, thereby adjusting selectivity between silicon oxide and silicon nitride, as in U.S. patent publication No. 20080116171A1 and korean patent publication No. KR1020090035063a, which both mention adding amino acids to the composition to inhibit the removal rate of silicon oxide, korean patent publication No. KR100851235B1 mentions inhibiting the removal rate of silicon nitride by means of cerium oxide abrasive and adding anionic or nonionic surfactant. Most of these compositions are neutral or acidic, OH in the system - The low concentration of (2) has weak polarization effect on Si-Si bond, so that the removal rate of polysilicon is obviously inhibited, and therefore, the application of the method has a certain limitation.
In addition, korean laid-open patent KR20100014849a proposes the addition of an aliphatic ammonium salt type cationic surfactant, such as octyltrimethylammonium bromide, decyltrimethylammonium bromide, lauryl trimethylammonium chloride, to a polysilicon composition to achieve the purpose of simultaneously suppressing the removal rate of silicon oxide and silicon nitride and improving the polishing selectivity, however, these additives also introduce harmful halogens into the polishing composition, are liable to cause corrosion damage to polishing equipment, and are liable to adversely affect the quality of the polished surface.
Therefore, there is a need to improve the composition of polishing compositions from a chemical formulation standpoint to achieve high polysilicon removal rates, high polishing selectivity, low polishing defects on a green, low-toxicity basis, overcoming the drawbacks of the prior art described above.
Disclosure of Invention
In order to solve the technical problems, the invention provides the polysilicon polishing composition, which can effectively improve the polysilicon removal rate and inhibit the silicon oxide and silicon nitride removal rate by adding the homopiperazine substances and the keto acid substances into the nano silicon dioxide colloid to serve as a rate accelerator and a selectivity inhibitor respectively, so that the high selectivity of the composition to polysilicon, silicon oxide and silicon nitride polishing is realized.
It is another object of the present invention to provide the use of such a polysilicon polishing composition in polysilicon chemical mechanical polishing.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a polysilicon polishing composition takes nano silicon dioxide colloid as abrasive, wherein the composition also comprises homopiperazine substances as speed accelerator and keto acid substances as selective inhibitor.
In a preferred embodiment, the polysilicon polishing composition comprises a nano-silica colloid, a homopiperazine-based material, a keto-acid-based material, a surfactant, a pH adjustor, a humectant, a bacteriostat, and deionized water.
In a preferred embodiment, the polysilicon polishing composition comprises the following components in percentage by weight: 5 to 30 weight percent of nano silicon dioxide colloid, 0.5 to 8 weight percent of homopiperazine substances, 0.05 to 2 weight percent of keto acid substances, 0.05 to 2 weight percent of surfactant, 0.05 to 3 weight percent of pH regulator, 0.01 to 2 weight percent of humectant, 0.005 to 1.0 weight percent of bacteriostat and the balance of deionized water.
In a more preferred embodiment, the polysilicon polishing composition comprises the following components in percentage by weight: 10 to 25 weight percent of nano silicon dioxide colloid, 2 to 6 weight percent of homopiperazine substances, 0.1 to 1 weight percent of keto acid substances, 0.1 to 1 weight percent of surfactant, 0.5 to 1.5 weight percent of pH regulator, 0.1 to 1.0 weight percent of humectant, 0.05 to 0.1 weight percent of bacteriostat and the balance of deionized water.
In a specific embodiment, the nanosilica colloid has an average particle size of from 30 to 90nm and a concentration of from 20 to 40wt%.
In one specific embodiment of the present invention, the homopiperazine is selected from homopiperazine, 1-Boc-homopiperazine, 1-methyl homopiperazine, 1-ethyl homopiperazine, 1-formyl homopiperazine, 1-acetyl homopiperazine, 1, 7-dimethyl-1, 4-homopiperazine, 1- (2-methoxyethyl) homopiperazine, 1- (2-aminoethyl) -4-methyl homopiperazine, 1-isobutyl-1, 4-homopiperazine, 1-pyrazin-2-yl-1, 4-homopiperazine, 1- (2-pyrimidinyl) homopiperazine, 1- (2-pyridinyl) -homopiperazine, 1- (3-methyl-2-pyridinyl) homopiperazine, 1- (6-methyl-2-piperidinyl) homopiperazine, 1-pyridin-2-ylmethyl-1, 4-homopiperazine, 1-benzyl homopiperazine, 1- (2-pyridin-4-ylethyl) -1, 4-homopiperazine, 1- (2-methylbenzyl) homopiperazine, 1- (4-methylbenzyl) homopiperazine, 1- (2-methyl-2-yl) -homopiperazine, 1- (2-methyl-2-pyrimidinyl) homopiperazine, 1- (2-hydroxy-Boc-2-pyridinyl) homopiperazine, 1- (6-methyl-2-piperidinyl) homopiperazine, 1- (2-benzyl) homopiperazine, 1-benzyl homopiperazine, 1- (2-methyl-4-benzyl) homopiperazine, and 2-hydroxy-1-2-methyl-homopiperazine, at least any one of 1-cyclobutyl-4- (piperidine-4-carbonyl) -1, 4-homopiperazine; preferably at least one of homopiperazine, 1-methyl homopiperazine, 1- (2-methoxyethyl) homopiperazine, 1-pyrazin-2-yl-1, 4-homopiperazine, 1- (2-pyrimidinyl) homopiperazine, and 1-benzyl homopiperazine.
In a specific embodiment, the ketoacids are selected from at least one of tetronic acid, 2-ketobutyric acid, 2-hydroxy-butanone, 2-imidazolidinone-4-carboxylic acid, croconic acid, 2-ketoglutaric acid, 2-pentanoic acid, (R) -3-ketocyclopentanoic acid, 4-cyclohexanone carboxylic acid, 4-ketopimelic acid, 2-indolone-4-carboxylic acid, bitter ketonic acid, 6-methylchromone-2-carboxylic acid, nalidixic acid, 9-fluorenone-1-carboxylic acid, 9-fluorenone-2-carboxylic acid, ketorolac acid, 2, 7-dimethyl-9-fluorenone-4-carboxylic acid, 3-methylflavone-8-carboxylic acid, 4-diethylaminoketonic acid; preferably at least one of tetronic acid, 2-pentanoic acid, 4-cyclohexanone carboxylic acid, 2-indolone-4-carboxylic acid, ketorolac acid and 4-diethylamino keto acid.
In a specific embodiment, the surfactant is at least one selected from the group consisting of fatty alcohol polyoxyethylene ether, laureth, isomerate polyoxyethylene ether, nonylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene alkylamine, and polyoxyethylene alkyl alcohol amide.
In a specific embodiment, the pH adjustor is selected from at least any one of tetrazole, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, pyrazole, 1-methylpyrazole, 3-methylpyrazole, 4-methylpyrazole; preferably, the pH of the silicon polishing composition is adjusted to 10 to 12.5.
In a specific embodiment, the humectant is selected from at least any one of propylene glycol, butylene glycol, hexylene glycol, glycerol, sorbitol, aminocyclopentanol.
In a specific embodiment, the bacteriostatic agent is selected from at least any one of 2-methyl-4-isothiazolin-3-one, 2-methyl-5-chloro-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one.
In another aspect, the use of the foregoing polysilicon polishing composition in polysilicon chemical mechanical polishing.
Compared with the prior art, the invention has the following beneficial effects:
the invention takes nano silicon dioxide colloid as basic abrasive, has the advantages of high polishing speed, clean polishing surface and difficult generation of concave defects (such as disving) on the surface of polysilicon, and in addition, the homopiperazine substances and the keto acid substances are respectively added into the polishing composition to serve as a speed accelerator and a selectivity inhibitor, so that the removal speed of polysilicon materials and the polishing selectivity of dielectric materials are improved, and meanwhile, the polishing composition also has the characteristics of green and low toxicity, and has remarkable advantages compared with the prior art.
Detailed Description
The following examples will further illustrate the method provided by the present invention for a better understanding of the technical solution of the present invention, but the present invention is not limited to the examples listed but should also include any other known modifications within the scope of the claims of the present invention.
The polysilicon polishing composition takes nano silicon dioxide colloid as a main polishing component, and is added with homopiperazine substances and keto acid substances as a rate accelerator and a selectivity inhibitor respectively, namely, on the basis of the existing polysilicon chemical mechanical polishing solution taking nano silicon dioxide colloid as an abrasive, the homopiperazine substances and the keto acid substances are added as auxiliary agents to obtain the polysilicon polishing composition.
Wherein the homopiperazine compound used is a heterocyclic weak organic acid having a short chain alkyl group, acyl group, pyrimidinyl group, pyridinyl group, piperidinyl group, and the like attached to the homopiperazine ring, the keto acid compound is an organic weak acid having both carbonyl and carboxyl groups, and the homopiperazine compound and the keto acid compound comprise, by mass, 0.5 to 8% of the polishing composition (including, but not limited to, 0.8%, 1.0%, 1.2%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 0.05 to 2% (including, but not limited to, 0.1%, 0.12%, 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.1.1%, 1.8% by mass).
Although silica sol abrasive mainly plays a mechanical grinding role in the composition, the hardness of the deposited polysilicon film layer is close to that of the silica abrasive, so that the removal rate of the silica sol abrasive is low, defects are easy to generate, and therefore, a rate accelerator needs to be added to soften the surface layer of the polysilicon. The compounds acting as rate promoters are capable of ionizing or hydrolyzing in the system to produce substantial amounts of OH - The Si-Si bonds on the surface of the polysilicon are polarized, thereby facilitating the continuous formation of a soft layer mainly composed of silicon oxide on the surface of the polysilicon, and the IC grade polishing composition requires that the rate accelerator does not contain various harmful metal ionsThe seed, and thus the rate accelerator of a typical polysilicon polishing composition, is primarily an organic base. Among them, the commonly used quaternary ammonium base compound and aliphatic organic amine have large corrosiveness and strong toxicity, and the static corrosion rate of the quaternary ammonium base compound and aliphatic organic amine to the surface of polysilicon is also large, which is easy to cause defects; in addition, the ionic strength of the substances in a concentrated system is also high, and the agglomeration of the silica sol abrasive is easy to cause.
The rate accelerator adopted by the invention is homopiperazine substances, belongs to heterocyclic organic amine, has large density of N lone pair electron cloud, is not easy to break N-H bond, has certain proton absorbing capability after being dissolved in water, and can lead OH in a system to be - Released, the whole ring structure is stable and positively charged, and is very easy to be matched with SiO on the surface of the polycrystalline silicon soft layer 3 2- A micelle is formed which acts as a rate accelerator to both increase the polishing rate and to facilitate the production of a high quality polished surface. The homopiperazine substance belongs to weak organic base, has small ionic strength, so that the addition amount of the homopiperazine substance in the composition can be relatively higher, and the agglomeration of silica sol particles is not caused under the condition of concentration. In addition, compared with piperazine which is heterocyclic organic amine, the piperazine has the advantages that the distance between two N in the homopiperazine ring is further, the electron-withdrawing induction effect between N and N is lower, the alkalinity is relatively stronger, and the polishing efficiency is higher.
In the polysilicon polishing process, it is highly desirable that the dielectric material be stable to prevent the occurrence of a large number of defects such as Dishing, erosion, and therefore selective inhibitors in the chemical assistant system are also important. The ketoacid substance serving as the selective inhibitor belongs to organic weak acid containing carbonyl, wherein the carbonyl and carboxyl exist in molecules at the same time, and after the ketoacid substance is ionized in an aqueous phase system, the electron withdrawing capacity of the whole group is enhanced by the carbonyl, so that compared with the common organic weak acid, the ketoacid is more easily and tightly adsorbed with silicon oxide and silicon nitride in a C-O-Si bond mode, and the adsorption of the ketoacid on the surface of polysilicon is not obvious. During polishing, the keto acid substance is contained in SiO 2 、Si 3 N 4 The surface adsorption film formation suppresses the mechanical friction action of the two materials, but has less influence on the polysilicon material, so that the polishing process is enhancedThe selectivity of the polysilicon to the silicon oxide and silicon nitride materials is favorable for reducing the generation of polishing defects.
Wherein the particle size of the nano silica colloid is 30-90nm, including but not limited to 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm and 90nm, and the concentration of the silica sol is 20-40wt%, including but not limited to 20wt%, 25wt%, 30wt%, 35wt% and 40wt%.
As the homopiperazine-based material, there is provided, for example selected from homopiperazine, 1-Boc-homopiperazine, 1-methyl homopiperazine, 1-ethyl homopiperazine, 1-formyl homopiperazine, 1-acetyl homopiperazine, 1, 7-dimethyl-1, 4-homopiperazine, 1- (2-methoxyethyl) homopiperazine, 1- (2-aminoethyl) -4-methyl homopiperazine, 1-isobutyl-1, 4-homopiperazine, 1-pyrazin-2-yl-1, 4-homopiperazine, 1- (2-pyrimidinyl) homopiperazine, 1- (2-pyridinyl) -homopiperazine, 1- (3-methyl-2-pyridinyl) homopiperazine, 1- (6-methyl-2-piperidinyl) homopiperazine, 1-pyridin-2-ylmethyl-1, 4-homopiperazine, 1-benzyl homopiperazine, 1- (2-pyridin-4-methylethyl) -1, 1- (3-methylbenzyl) homopiperazine, 1- (4-methylbenzyl) homopiperazine, 1-Boc-5-methyl-1, 4-hydroxy-Boc-1-2-pyridinyl) homopiperazine, 1- (2-hydroxy-2-ethyl-homopiperazine, 1-2-hydroxy-2-methyl-1-2-piperidinyl-homopiperazine, at least any one of 1-cyclobutyl-4- (piperidine-4-carbonyl) -1, 4-homopiperazine, for example, any one, any two or more of the above homopiperazines, preferably homopiperazine, 1-methyl homopiperazine, 1- (2-methoxyethyl) homopiperazine, 1-pyrazin-2-yl-1, 4-homopiperazine, 1- (2-pyrimidinyl) homopiperazine, 1-benzyl homopiperazine.
The ketoacids are, for example, selected from one or more of tetronic acid, 2-ketobutyric acid, 2-hydroxy-butanone, 2-imidazolidinone-4-carboxylic acid, croconic acid, 2-ketoglutaric acid, 2-pentanoic acid, (R) -3-ketocyclopentanoic acid, 4-cyclohexanone carboxylic acid, 4-ketopimelic acid, 2-indolone-4-carboxylic acid, picronic acid, 6-methylchromone-2-carboxylic acid, nalidixic acid, 9-fluorenone-1-carboxylic acid, 9-fluorenone-2-carboxylic acid, ketorolac, 2, 7-dimethyl-9-fluorenone-4-carboxylic acid, 3-methylflavone-8-carboxylic acid, and 4-diethylaminoketoacid, and are preferably selected from the group consisting of tetronic acid, 2-pentanoic acid, 4-cyclohexanone carboxylic acid, 2-indolone-4-carboxylic acid, ketorolac, and 4-diethylaminoketonic acid.
Besides the nano silicon dioxide colloid which is an abrasive and is added with three main components of homopiperazine substances and keto-acid substances, the polishing composition is not limited by any other additive components added in the polishing composition, can be suitable for various conventional polysilicon chemical mechanical polishing liquid systems, and can be added into the polishing composition by a technician according to the requirements of improving the polishing surface quality and improving the stability of the composition, and one or more of a surfactant, a pH regulator, a humectant and a bacteriostat can be selected at will.
Wherein the surfactant is at least one selected from fatty alcohol polyoxyethylene ether, laureth, isomeric alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene alkylamine and polyoxyethylene alkyl alcohol amide, for example, any one, any two or more of the above speed promoters, preferably fatty alcohol polyoxyethylene ether, polyoxyethylene alkylamine and polyoxyethylene alkyl alcohol amide. The surfactant is used for reducing the surface tension of the composition, reducing the contact angle between the composition and the surface of the polysilicon material, and enhancing the spreadability of the composition on the surface of the polysilicon material, thereby reducing the surface roughness of the polysilicon material after polishing, and being beneficial to improving the uniformity of the surface of the wafer after polishing and improving the quality of the polished surface.
The pH adjuster is, for example, at least one selected from tetrazole, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, pyrazole, 1-methylpyrazole, 3-methylpyrazole, and 4-methylpyrazole, and is, for example, preferably, tetrazole or imidazole, in combination of any one or two or more of the above pH adjusters. The pH regulator is used for regulating the pH value of the concentrated solution, so that the concentrated solution is prevented from being too strong in alkalinity to cause the dissolution of nano silicon oxide particles, and anions generated by ionization or hydrolysis of the concentrated solution have complexation effect on metal ions in the composition.
The humectant is, for example, at least one selected from propylene glycol, butylene glycol, hexylene glycol, glycerol, sorbitol, and aminocyclopentanol, and is, for example, any one, a combination of any two or more of the above humectants, preferably glycerol and aminocyclopentanol. The humectant is used for inhibiting water loss of the composition during storage to enhance stability of silica sol particles and prolong shelf life of the composition.
The bacteriostatic agent is, for example, at least one selected from the group consisting of 2-methyl-4-isothiazolin-3-one, 2-methyl-5-chloro-4-isothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one, and for example, any one, a combination of any two or more of the above bacteriostatic agents, preferably 2-n-octyl-4-isothiazolin-3-one. The bacteriostatic agent is used for inhibiting the propagation of bacteria and fungi in the polishing solution and preventing the aging failure of the polishing solution caused by the metabolites of microorganisms.
In a specific embodiment, the composition is prepared from the following components in parts by weight:
wherein the polysilicon polishing composition has a pH of 10 to 12.5, including for example, but not limited to, 10, 10.5, 11, 11.5, 12, 12.5, preferably 11 to 12.
The preparation method of the polysilicon polishing composition of the invention is, for example, a method for preparing the polysilicon polishing composition by mixing the components according to the method known in the art, specifically, for example, a method for preparing the polysilicon polishing composition comprises the step of mixing homopiperazine substances and keto acid substances with nano silicon dioxide colloid and other auxiliary agents.
In a preferred embodiment, the homopiperazine substance, the keto acid substance, the surfactant, the pH regulator, the humectant and the bacteriostatic agent are fully mixed and dispersed to form the chemical auxiliary agent of the composition.
Then, adding the chemical auxiliary agent into the nano silicon dioxide colloid, and fully stirring and dispersing to form the polysilicon polishing composition of the invention, wherein the dispersing means in the process comprise any one or more of mechanical stirring, ultrasonic dispersing and magnetic stirring.
The invention is further illustrated, but not limited, by the following more specific examples.
In the following examples, the polishing machine used in the polishing test of the polysilicon wafer was a Speedfam 36B type single-sided polishing machine; the polishing pad used was of the IC1010 type, the polishing material was 200mm wafer, the polishing rotation speed was 65rpm, the polishing pressure was 2.0psi, the flow rate was 1.2L/min, the polishing time was 1min, and the polishing temperature was controlled at 30 to 32 ℃. The polishing solution is filtered and then is conveyed to a polishing disk by a peristaltic pump, a trimmer is used for trimming and maintaining the polishing pad after each polishing, and pre-polishing is carried out before each polishing.
Removal rate test: the thickness of the polysilicon film, the thickness of the silicon oxide film and the thickness of the silicon nitride film which are removed by polishing are respectively measured by a film thickness meter, and the removal rate-MRR-of the three is respectively calculated according to the polishing time)。
And selectively comparing, namely calculating the ratio of the polysilicon removal rate to the silicon oxide removal rate in the same time, calculating the ratio of the polysilicon removal rate to the silicon nitride removal rate in the same time, and comparing.
Unless otherwise specified, the raw materials and reagents used in the examples and comparative examples of the present invention were commercially available.
Example 1
Dissolving 10g of homopiperazine, 1g of tetronic acid, 1g of fatty alcohol polyoxyethylene ether, 1g of tetrazole, 0.2g of glycerol and 0.1g of 2-n-octyl-4-isothiazolin-3-ketone in 400g of deionized water, uniformly stirring, adding the solution into 500g of 20wt% nano silicon dioxide colloid (average particle size of 30 nm) while stirring, continuously adding deionized water until the total mass of the dispersion is 2kg, magnetically stirring for 30min, packaging, and obtaining the pH value of the dispersion which is 10.
Example 2
20g of 1-methyl homopiperazine, 2g of 2-pentanoic acid, 2g of polyoxyethylene alkylamine, 10g of tetrazole, 2g of glycerol and 1g of 2-n-octyl-4-isothiazolin-3-ketone are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1000g of 20wt% nano silicon dioxide colloid (average particle size is 30 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 10.5.
Example 3
40g of 1- (2-methoxyethyl) homopiperazine, 6g of 4-cyclohexanone carboxylic acid, 8g of polyoxyethylene alkyl alcohol amide, 12g of tetrazole, 6g of aminocyclopentanol and 1.6g of 2-n-octyl-4-isothiazolin-3-one are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1200g of 30wt% nano silicon dioxide colloid (average particle size of 50 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 11.0.
Example 4
80g of 1-pyrazin-2-yl-1, 4-homopiperazine, 10g of 2-indolone-4-carboxylic acid, 12g of polyoxyethylene alkylamine, 22g of imidazole, 10g of aminocyclopentanol and 2g of 2-n-octyl-4-isothiazolin-3-one are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1000g of 40wt% nano silicon dioxide colloid (average particle size 70 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 11.3.
Example 5
100g of 1- (2-pyrimidinyl) homopiperazine, 16g of ketorolac, 16g of polyoxyethylene alkyl alcohol amide, 30g of imidazole, 16g of aminocyclopentanol and 7g of 2-n-octyl-4-isothiazolin-3-one are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1250wt% of nano silicon dioxide colloid (average particle size 70 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 11.5.
Example 6
120g of 1-benzyl homopiperazine, 20g of 4-diethylamino keto acid, 20g of polyoxyethylene alkyl alcohol amide, 50g of imidazole, 20g of aminocyclopentanol and 2g of 2-n-octyl-4-isothiazolin-3-ketone are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1000g of 40wt% nano silicon dioxide colloid (average particle size of 70 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 11.5.
Example 7
160g of homopiperazine, 30g of 2-pentanoic acid, 28g of polyoxyethylene alkylamine, 60g of imidazole, 30g of aminocyclopentanol, 20g of 2-n-octyl-4-isothiazolin-3-one are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1000g of 40wt% nano silicon dioxide colloid (average particle size 50 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 12.0.
Example 8
80g of 1-methyl homopiperazine, 40g of tetronic acid, 40g of fatty alcohol polyoxyethylene ether, 20g of tetrazole, 40g of glycerol and 1.2g of 2-n-octyl-4-isothiazolin-3-ketone are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1000g of 30wt% nano silicon dioxide colloid (average particle size is 50 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 11.6.
Example 9
40g of 1- (2-pyrimidinyl) homopiperazine, 10g of ketorolac, 10g of polyoxyethylene alkylamine, 4g of tetrazole, 10g of glycerol and 10g of 2-n-octyl-4-isothiazolin-3-one are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1500g of 40wt% nano silicon dioxide colloid (average particle size 90 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 11.2.
Example 10
100g of 1-methyl homopiperazine, 10g of 4-diethylamino keto acid, 6g of fatty alcohol polyoxyethylene ether, 40g of imidazole, 16g of glycerol and 2g of 2-n-octyl-4-isothiazolin-3-ketone are dissolved in 400g of deionized water, uniformly stirred, then the solution is added into 1200g of 30wt% nano silicon dioxide colloid (average particle size is 50 nm) while stirring, deionized water is continuously added until the total mass of the dispersion is 2kg, magnetic stirring is carried out for 30min, packaging is carried out, and the pH value of the dispersion is 12.5.
Comparative example 1
The auxiliary was prepared in the same manner as in example 1 except that 10g of piperazine was added without adding additional piperazine.
Comparative example 2
The auxiliary was prepared in the same manner as in example 6 except that 120g of ethylenediamine was added without adding 1-benzyl homopiperazine.
Comparative example 3
The auxiliary was prepared in the same manner as in example 4 except that 80g of tetraethylammonium hydroxide was added to the auxiliary without adding 1-pyrazin-2-yl-1, 4-homopiperazine.
Comparative example 4
The auxiliary was prepared in the same manner as in example 3 except that 6g of oxalic acid was added to the auxiliary without adding 4-cyclohexanone carboxylic acid.
Comparative example 5
The auxiliary agent was added with 16g malonic acid without ketorolac, and the other steps were the same as in example 5.
Comparative example 6
The auxiliary agent was not added with ketorolac, and the other steps were the same as in example 5.
Polishing tests were conducted after diluting the polishing compositions of each example and comparative example at a volume ratio of 1:10, and the polishing test results are shown in Table 1 below:
table 1 polishing test results
Comparing table 1 above with example 1, it can be seen that example 1, with the addition of the same quality homopiperazine, has significantly higher polysilicon removal rate than comparative example 1, while comparative example and example have no significant difference in silicon oxide, silicon nitride removal rate, but the dishing defect of comparative example is much greater than example, indicating that homopiperazine has a higher polishing rate as a rate accelerator for the composition, and better polished surface quality.
Comparing comparative example 2 with example 6, comparative example 3 and example 4, it can be found that the removal rates of polysilicon in comparative example 2 and comparative example 3 do not exceed those in example 6 and example 4 under the same conditions, and the removal rates of silicon oxide and silicon nitride in comparative example are slightly higher than those in example, and dishing corrosion caused by polishing is also higher than that in example, so that the polishing selectivity of comparative example is lower than that of example, and the polishing quality is also poorer than that of example. This shows that the homopiperazine substance used in the examples has better effect of removing polysilicon and can avoid polishing defect than the aliphatic organic amine or organic ammonium used in the comparative examples, and the reason is probably that the chemical action of the homopiperazine substance in the polishing process is more coordinated with the mechanical action of the abrasive, and is less prone to malignant corrosion or overpolishing.
Comparing comparative example 4 with example 3 in table 1 above, comparative example 5 and example 5, it can be found that the removal rates of comparative example 3 and comparative example 4 for silicon oxide and silicon nitride are significantly higher than those of example 3 and example 5 under the same conditions, and the removal rates of comparative example and example for polysilicon material are close, so that the selectivity of comparative example is significantly lower than that of example, and the dishing defect generated by polishing is significantly higher than that of example. This indicates that the addition of a keto acid compound as a selective inhibitor to the composition can exert an effect of suppressing the removal rate of silicon oxide or silicon nitride more than that of a general weak organic acid (e.g., oxalic acid or malonic acid). The reason is probably that the keto acid substance contains carbonyl groups in the molecule and can be adsorbed by bonding to the surface of silicon oxide or silicon nitride more than the general weak organic acid. The effect of the ketonic acid substance on improving polishing selectivity and reducing polishing defects is also reflected by comparing comparative example 6 with example 5.
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.
Claims (13)
1. The polysilicon polishing composition takes nano silicon dioxide colloid as an abrasive, and is characterized by further comprising homopiperazine substances as a rate accelerator and keto acid substances as selective inhibitors; the content of each component is as follows: 5 to 30 weight percent of nano silicon dioxide colloid, 0.5 to 8 weight percent of homopiperazine substances, 0.05 to 2 weight percent of keto acid substances, 0.05 to 2 weight percent of surfactant, 0.05 to 3 weight percent of pH regulator, 0.01 to 2 weight percent of humectant, 0.005 to 1.0 weight percent of bacteriostat and the balance of deionized water.
2. The polysilicon polishing composition as set forth in claim 1, wherein the contents of the components are: 10 to 25 weight percent of nano silicon dioxide colloid, 2 to 6 weight percent of homopiperazine substances, 0.1 to 1 weight percent of keto acid substances, 0.1 to 1 weight percent of surfactant, 0.5 to 1.5 weight percent of pH regulator, 0.1 to 1 weight percent of humectant, 0.05 to 0.1 weight percent of bacteriostat and the balance of deionized water.
3. The polysilicon polishing composition as set forth in claim 1 or 2, wherein the average particle diameter of the nano-silica colloid is 30 to 90nm and the mass concentration is 20 to 40wt%.
4. The polysilicon polishing composition of claim 1 or 2, wherein the homopiperazine is selected from the group consisting of homopiperazine, 1-methyl homopiperazine, 1-ethyl homopiperazine, 1-Boc-homopiperazine, 1-formyl homopiperazine, 1-acetyl homopiperazine, 1, 7-dimethyl-1, 4-homopiperazine, 1- (2-methoxyethyl) homopiperazine, 1- (2-aminoethyl) -4-methyl homopiperazine, 1-isobutyl-1, 4-homopiperazine, 1-pyrazin-2-yl-1, 4-homopiperazine, 1- (2-pyrimidinyl) homopiperazine, 1- (2-pyridinyl) -homopiperazine, 1- (3-methyl-2-pyridinyl) homopiperazine, 1- (6-methyl-2-piperidinyl) homopiperazine, 1-pyridin-2-ylmethyl-1, 4-homopiperazine, 1- (2-pyridin-4-ylethyl) -1, 4-homopiperazine, 1- (2-methylbenzyl) homopiperazine, 1- (3-methyl-4-homopiperazine, 1- (2-benzyl) homopiperazine, 1-benzyl-4-methyl-homopiperazine, 1- (2-benzyl-4-hydroxy-homopiperazine, 1- (2-methyl-2-pyridinyl) -homopiperazine, 1- (3-methyl-2-pyridinyl) homopiperazine, 1-2-hydroxy-methyl-1, 4-methyl-homopiperazine, 2-methyl-2-piperidinyl-piperazine, 1-2-methyl-2-carbonyl-homopiperazine At least any one of 2-Boc-4- (2-pyridyl) homopiperazine and 1-cyclobutyl-4- (piperidine-4-carbonyl) -1, 4-homopiperazine.
5. The polysilicon polishing composition as set forth in claim 4, wherein the homopiperazine is at least one selected from the group consisting of homopiperazine, 1-methyl homopiperazine, 1- (2-methoxyethyl) homopiperazine, 1-pyrazin-2-yl-1, 4-homopiperazine, 1- (2-pyrimidinyl) homopiperazine, and 1-benzyl homopiperazine.
6. The polysilicon polishing composition of claim 1 or 2, wherein the ketoacid species is selected from at least one of the group consisting of tetronic acid, 2-ketobutyric acid, 2-hydroxy-butanone, 2-imidazolidinone-4-carboxylic acid, croconic acid, 2-ketoglutaric acid, 2-pentanoic acid, (R) -3-ketocyclopentanoic acid, 4-cyclohexanone carboxylic acid, 4-ketopimelic acid, 2-indolone-4-carboxylic acid, picronic acid, 6-methylchromone-2-carboxylic acid, naphthyridonec acid, 9-fluorenone-1-carboxylic acid, 9-fluorenone-2-carboxylic acid, ketorolac acid, 2, 7-dimethyl-9-fluorenone-4-carboxylic acid, 3-methylflavone-8-carboxylic acid, and 4-diethylamino-carboxylic acid.
7. The polysilicon polishing composition of claim 6, wherein the ketoacid species is selected from at least one of the group consisting of tetronic acid, 2-pentanoic acid, 4-cyclohexanone carboxylic acid, 2-indolone-4-carboxylic acid, ketorolac acid, 4-diethylamino ketoacid.
8. The polysilicon polishing composition according to claim 1 or 2, wherein the surfactant is nonionic and is at least one selected from the group consisting of fatty alcohol polyoxyethylene ether, polyoxyethylene lauryl ether, polyoxyethylene isomeric alcohol ether, polyoxyethylene nonylphenol ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkylamine, and polyoxyethylene alkyl alcohol amide.
9. The polysilicon polishing composition according to claim 1 or 2, wherein the pH adjuster is selected from at least any one of tetrazole, imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, pyrazole, 1-methylpyrazole, 3-methylpyrazole, 4-methylpyrazole.
10. The polysilicon polishing composition according to claim 1 or 2, wherein the pH of the polysilicon polishing composition is adjusted to 10 to 12.5.
11. The polysilicon polishing composition of claim 1 or 2, wherein the humectant is selected from at least any one of propylene glycol, butylene glycol, hexylene glycol, glycerol, sorbitol, aminocyclopentanol.
12. The polysilicon polishing composition according to claim 1 or 2, wherein the bacteriostat is at least any one selected from the group consisting of 2-methyl-4-isothiazolin-3-one, 2-methyl-5-chloro-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one.
13. Use of the polysilicon polishing composition of any one of claims 1-12 in polysilicon chemical mechanical polishing.
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| JP2008032975A (en) * | 2006-07-28 | 2008-02-14 | Toyo Ink Mfg Co Ltd | Polymerizable composition, negative resist using the same and image pattern forming method using the negative resist |
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