JP2005179421A - Abrasive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abrasive composition which is suitably used in a substrate surface planarization step, especially a shallow trench isolation formation step in a semiconductor device manufacturing step, polishes a silicon oxide film at a high speed and yields a large selection ratio of polishing rate of the silicon oxide film to that of a silicon nitride film. <P>SOLUTION: The abrasive composition contains a phosphorus-containing nonionic surfactant and an aqueous sol containing cerium oxide particles and further contains an anionic surfactant. The phosphorus-containing nonionic surfactant is at least one chosen from the group consisting of a monoester phosphate, a diester phosphate and a triester phosphate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is particularly suitable for a shallow trench isolation formation step in a substrate surface planarization step in a semiconductor device manufacturing process, and includes an aqueous sol containing cerium oxide particles and a nonionic phosphorus-containing surfactant. It is related with the composition for use.

An organic compound in which abrasive particles mainly composed of cerium oxide and a surfactant are composed of COOH (carboxyl group) or COOM ₁ (M ₁ is an atom or a functional group that can form a salt by substituting a hydrogen atom of the carboxyl group). A method of polishing SiO ₂ , SiON, SiOF, boron phosphosilicate glass, and phosphosilicate glass on a device substrate with an abrasive containing (Patent Document 1)
Japanese Patent No. 3130279 also discloses an abrasive comprising ceria and a polymer acid such as polyacrylic acid. (Patent Document 2)
Japanese Patent No. 3278532 (Claims) Japanese Patent No. 3130279 (Claims)

The present invention provides a polishing composition having a high polishing rate of a silicon oxide film and a high selection ratio of a polishing rate of a silicon oxide film / a silicon nitride film. A polishing composition suitable for a planarization process of a substrate surface in a manufacturing process of a semiconductor element, particularly a formation process of shallow trench isolation (separation of Si and SiO ₂ on a substrate), and efficiently forms shallow trench isolation. be able to.

As a first aspect of the present invention, a polishing composition comprising an aqueous sol containing cerium oxide particles and a nonionic phosphorus-containing surfactant,
As a second aspect, the polishing composition according to the first aspect further comprising an anionic surfactant,
As a third aspect, the first aspect or the second aspect, wherein the nonionic phosphorus-containing surfactant is at least one phosphate ester selected from the group consisting of a phosphate monoester, a phosphate diester, and a phosphate triester. The polishing composition according to the aspect, and as a fourth aspect, the anionic surfactant is polyacrylic acid ammonium salt, polymethacrylic acid ammonium salt, ammonium oleate, ammonium lauryl sulfate, lauryl sulfate triethanolamine, polyoxy It is at least one anionic surfactant selected from the group consisting of ammonium ethylene lauryl ether sulfate, sodium polyacrylate, sodium polymethacrylate, sodium oleate, sodium lauryl sulfate, and sodium polyoxyethylene lauryl ether sulfate. The polishing composition according to any one of the first aspect to the third aspect.

  The polishing composition containing the phosphorus-containing surfactant of the present invention is a polishing composition having a high polishing rate selection ratio of silicon oxide film / silicon nitride film and a high polishing rate of silicon oxide film. Therefore, it is suitable as a polishing agent used for planarization polishing in a semiconductor device manufacturing process generally called CMP (Chemical Mechanical Polishing). In particular, since the silicon nitride film used as a protective film can be precisely polished without damaging it, it is used in an element isolation process of a semiconductor device generally called STI (Shallow Trench Isolation). Suitable as an abrasive. Further, it is also suitable as an abrasive used for polishing a low dielectric constant material for an interlayer insulating film of a semiconductor device such as a siloxane, organic polymer, porous material or CVD polymer. Examples of siloxane-based materials include hydrogenated silsesquioxane, methyl silsesquioxane, and hydrogenated methyl silsesquioxane. Examples of the organic polymer material include polyarylene ether, thermally polymerizable hydrocarbon, perfluorohydrocarbon, polyquinoline, and fluorinated polyimide. Examples of porous materials include xerogel and silica colloid. Examples of CVD polymer materials include fluorocarbons, aromatic hydrocarbon polymers, and siloxane polymers.

  Here, the substrate mainly composed of silica refers to, for example, quartz, quartz glass, a glass hard disk, an organic film of a semiconductor device, a low dielectric constant film, an interlayer insulating film, and trench isolation CMP. In addition, it can be applied to polishing other substrates such as optical crystal materials such as lithium niobate and lithium tantalate, ceramic materials such as aluminum nitride, alumina, ferrite and zirconia, and metals such as aluminum, copper and tungsten.

  The aqueous sol of the present invention contains ceric oxide particles having high crystallinity. The particle diameter converted from the specific surface area of the cerium oxide particles by the gas adsorption method (BET method) is observed as an average value of the particle diameters of the individual particles.

  The particle diameter converted from the specific surface area by the gas adsorption method (BET method) of the cerium oxide particles contained in the aqueous sol of the present invention is 10 to 200 nm, more preferably 20 to 100 nm. If it is smaller than 10 nm, the polishing rate is too slow, and if it is larger than 200 nm, scratches are likely to occur, such being undesirable.

  In laser diffraction method, the particle diameter of the particles in the sol is observed with a laser diffraction particle diameter measured by a device such as MASTERSIZER (manufactured by MALVERN). If there is aggregation or adhesion, the particle diameter is observed. Is done.

The aqueous sol used in the present invention has a particle size of d10 of 50 to 90 nm, a particle size of d50 of 80 to 500 nm, and a particle size of d90 of 2000 nm or less, more preferably a particle size of d10 of 50 by laser diffractometry. It is an aqueous sol containing crystalline cerium oxide particles having a particle diameter of ˜70 nm, a d50 particle diameter of 80 to 150 nm, and a laser diffraction method d90 of 500 nm or less.

  The crystalline cerium oxide particles have a particle diameter of 20 to 300 nm when observed with a transmission electron microscope (TEM). The aqueous sol containing cerium oxide particles used in the present invention is close to monodisperse particles, so that even if it is left for a long time, the particles do not settle, and easily return to the dispersed state at the time of manufacture by light stirring or shaking. It is stable for more than 1 year even if stored in

  The aqueous sol containing the crystalline cerium oxide particles used in the present invention is obtained by using crystalline cerium oxide powder obtained by firing cerium carbonate at 300 to 1100 ° C. or using commercially available cerium oxide powder as a raw material. Can be produced by wet pulverization in an aqueous medium.

  This wet pulverization is performed by a wet ball mill, a sand grinder, an attritor, a pearl mill, an ultrasonic homogenizer, a pressure homogenizer, an optimizer, or the like.

  Water-soluble dispersants added during wet grinding are acids such as nitric acid, hydrochloric acid and acetic acid, polyacrylic acid, polyacrylic acid ammonium salt, polyacrylic acid sodium salt, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid Water-soluble polymers such as sodium, anionic surfactants such as ammonium oleate, ammonium lauryl sulfate, triethanolamine lauryl sulfate, polyoxyethylene lauryl ether ammonium sulfate, cationic surfactants, nonionic surfactants, Water-soluble alkali silicate, hydroxide 4 using halogenated quaternary ammonium, quaternary ammonium hydroxide, or a mixture thereof, lithium hydroxide, sodium hydroxide, potassium hydroxide, aqueous ammonia and the like as a water-soluble alkali source Grade ammonium, hexametaphosphate Moniumu, and sodium hexametaphosphate.

  Further, an aqueous sol containing crystalline ceric oxide particles described in JP-A-8-81218, JP-A-10-94955, JP-A-10-95614, and JP-A-2003-27045 is used. It can also be used.

  That is, an aqueous medium containing ceric hydroxide and nitrate is adjusted to a pH of 8 to 11 using an alkaline substance, and then heated under pressure at a temperature of 100 to 200 ° C. An aqueous sol containing ceric oxide particles having a particle size of 03 to 5 μm (Japanese Patent Laid-Open No. 8-81218).

  An aqueous sol containing ceric oxide particles heat-treated in an aqueous medium at a temperature of 50 to 250 ° C. in the presence of an ammonium salt (Japanese Patent Laid-Open No. 10-94955).

A cerium (III) hydroxide suspension is formed by reacting a cerium (III) salt with an alkaline substance in an aqueous medium in an inert gas atmosphere at an (OH) / (Ce ³⁺ ) molar ratio of 3-30. After that, crystalline cerium oxide having a particle size of 0.005 to 5 μm, wherein oxygen or a gas containing oxygen is blown into the suspension immediately under atmospheric pressure at a temperature of 10 to 95 ° C. An aqueous sol containing particles (Japanese Patent Laid-Open No. 10-95614).

The following first step and second step, first step: a cerium (III) salt and an additive component comprising a lanthanum (III) salt, neodymium (III) salt or a combination thereof in an aqueous medium, a lanthanum atom, a neodymium atom Or the combination is set to X, and the molar ratio of (OH ⁻ ) / (Ce ³⁺ + X ³⁺ ) and an aqueous solution mixed at a ratio of 0.001 to 0.5 in terms of X / (Ce + X) molar ratio A step of reacting at a ratio of 3 to 30 as a ratio to produce a suspension in which cerium hydroxide (III) and the hydroxide of additive component X (III) are uniformly mixed; and second step: obtained Obtained through a process of blowing oxygen or oxygen-containing gas into the suspension at a temperature of 10 to 95 ° C., having a particle size of 0.005 to 1 μm, and an X / (Ce + X) molar ratio Converted to a ratio of 0.001 to 0.5 Tan compound, neodymium compound or sol particles are dispersed in a medium to which a main component crystalline cerium oxide of the cubic system containing the additive component consisting of a combination thereof (JP 2003-27045).

The cerium oxide concentration in the polishing composition is 0.05 to 5% by weight, more preferably 0.1 to 1.5% by weight.
The concentration of the nonionic phosphorus-containing surfactant in the polishing composition is preferably 0.001 to 10% by weight. An increase in the concentration of the nonionic phosphorus-containing surfactant is not preferable because the polishing rate of the silicon oxide film decreases.

  As the nonionic phosphorus-containing surfactant, those having a molecular weight in the range of 110 to 10,000 are preferably used.

  Nonionic phosphorus-containing surfactants include phosphate monoesters, phosphate diesters, and phosphate triesters. Examples of phosphoric acid monoesters include phosphoric acid monoalkyl esters and phosphoric acid monoaryl esters, such as phosphoric acid monomethyl ester, phosphoric acid monoethyl ester, phosphoric acid monophenyl ester, and phosphoric acid monotosyl ester.

  Examples of phosphoric acid diesters include phosphoric acid dialkyl esters, phosphoric acid alkylaryl esters, and phosphoric acid diaryl esters, such as phosphoric acid dimethyl ester, phosphoric acid diethyl ester, phosphoric acid ethylphenyl ester, and phosphoric acid diphenyl ester.

  Examples of phosphoric acid triesters include phosphoric acid trialkyl esters, phosphoric acid alkyl diaryl esters, phosphoric acid dialkyl aryl esters, phosphoric acid alkyl diaryl esters, and phosphoric acid triaryl esters, such as phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid triaryl ester. Examples thereof include acid methyl diphenyl ester, phosphoric acid dimethyl phenyl ester, phosphoric acid methyl diphenyl ester, and phosphoric acid triphenyl ester.

  And as for said phosphoric acid monoester, phosphoric acid diester, and phosphoric acid triester, it is preferable to use the phosphoric acid ester in which an ester part has an alkyl ether group and an aryl ether group.

  Formula (1) as phosphoric acid monoester,

Is mentioned.

  Formula (2) as phosphoric diester

Is mentioned.

  Formula (3) as phosphate triester

Is mentioned.

  In the above formulas (1) to (3), n is the average added mole number of ethylene oxide, and n = 2 to 40. R is an alkyl group having 8 to 30 carbon atoms or an alkylphenol group. The phosphate ester can be used as a mixture of phosphate monoester, phosphate diester and phosphate triester.

  As such a phosphoric acid ester, a product name Phosphanol RP-710 manufactured by Toho Chemical Co., Ltd. can be cited as an example in which the R portion has an aromatic group (for example, a phenyl group), and the R portion is aliphatic. As a thing, Toho Chemical Co., Ltd. brand name phosphanol RS-710 is mentioned, These can be used as nonionic phosphorus containing surfactant.

  The concentration of the anionic surfactant in the polishing composition is preferably 0.001 to 10% by weight. An increase in the concentration of the anionic surfactant is not preferable because the polishing rate of the silicon oxide film is greatly reduced.

  Anionic surfactants include polyacrylic acid ammonium salt, polymethacrylic acid ammonium salt, ammonium oleate, ammonium lauryl sulfate, lauryl sulfate triethanolamine, polyoxyethylene lauryl ether ammonium sulfate, sodium polyacrylate, sodium polymethacrylate, At least one anionic surfactant selected from the group consisting of sodium oleate, sodium lauryl sulfate, and sodium polyoxyethylene lauryl ether sulfate can be added. These anionic surfactants preferably have a molecular weight in the range of 500 to 50,000.

Example 1
After 192 kg of commercially available cerium carbonate powder having a purity of 99.9% was baked in an electric furnace at 350 ° C. for 5 hours, the temperature was raised to 740 ° C. and baked at 740 ° C. for 15 hours. When the obtained powder was cooled and observed with a scanning electron microscope (SEM), it was a particle having a primary particle diameter of 30 to 50 nm, and 98 kg was obtained as a calcined powder. When this was measured with a powder X-ray diffractometer, it had main peaks at diffraction angles 2θ = 28.6 °, 47.5 ° and 56.4 °, and had cubic crystals as described in ASTM card 34-394. It was found to be cerium oxide, which coincided with the characteristic peak of cerium oxide. Moreover, the specific surface area value by the gas adsorption method (BET method) of this cerium oxide particle was 15 m < ² > / g, and was 56 nm as a particle diameter converted from the specific surface area by a gas adsorption method.

A 135 mm radius x 73 cm polyethylene lined ball mill container was charged with 135 kg of 1 mmφ zirconia beads, and 13.5 kg of the obtained cerium oxide powder, 27.0 kg of pure water and 107 g of 10% nitric acid were charged, and the rotation speed was 35 rpm for 6 hours. Crushed. Bead separation was performed using pure water to obtain 61 kg (A-1) of an aqueous cerium oxide sol having a solid content of 23% by weight, a pH of 5.8, and an electric conductivity of 350 μm / S. The particle diameter of the laser diffraction method was measured for this slurry with MASTERSIZER2000 (manufactured by MARVERN). The d10 particle diameter of the laser diffraction method was 71 nm, the d50 particle diameter was 175 nm, and the d90 particle diameter was 782 nm. The average particle size of the dynamic light scattering method was 270 nm. The specific surface area value of the cerium oxide particles obtained by drying at 300 ° C. by gas adsorption method (BET method) was 22 m ² / g, and the particle diameter converted from the specific surface area by gas adsorption method was 38 nm.

Example 2
After 4 kg of commercially available cerium carbonate powder having a purity of 99.9% was baked in an electric furnace at 350 ° C. for 5 hours, the temperature was raised to 840 ° C. and baked at 840 ° C. for 15 hours. When the obtained powder was observed with a scanning electron microscope (SEM), 2 kg of sintered powder of particles having a primary particle diameter of 100 to 200 nm was obtained. When this calcined powder was measured with a powder X-ray diffractometer, it had main peaks at diffraction angles 2θ = 28.6 °, 47.5 ° and 56.4 °, and the cubic system described in ASTM card 34-394. It was found to be cerium oxide, consistent with the characteristic peak of crystalline cerium oxide. Moreover, the specific surface area value by the gas adsorption method (BET method) of the cerium oxide particles was 4.1 m ² / g, and the particle diameter converted from the specific surface area by the gas adsorption method was 204 nm.

A slurry obtained by adding 640 g of ceric oxide obtained to an aqueous solution obtained by mixing 21.3 g of 30 wt% ammonium polyacrylate (average molecular weight: 1600) and 620 g of pure water as a dispersant was charged with 3800 g of 1 mmφ zirconia beads. It put into a certain 3L ball mill container, and wet-ground for 32 hours at 60 rpm. The beads were separated using pure water, and 2984 g of an aqueous sol (A-2) having a pH of 9.3, an electric conductivity of 950 μS / cm, a viscosity of 1.1 mPa · s, and a solid content of 22% by weight was obtained. The particle diameter of the laser diffraction method was measured for this slurry with MASTERSIZER2000 (manufactured by MARVERN). The d10 particle size of the laser diffraction method was 60 nm, the d50 particle size was 115 nm, and the d90 particle size was 239 nm. The average particle size of the dynamic light scattering method was 218 nm. The specific surface area value of the cerium oxide particles obtained by drying the slurry at 400 ° C. by gas adsorption method (BET method) was 14 m ² / g, and the particle diameter converted from the specific surface area by gas adsorption method was 62 nm. It was. The aqueous sol had almost no sediment even after standing for a long time.
A nonionic phosphorus-containing surfactant (trade name: Phosphanol RP710, manufactured by Toho Chemical Co., Ltd.) nonionic phosphorus was added to the aqueous sol (A-1 and A-2) obtained in Example 1 and Example 2. Containing polishing agent (trade name: Phosphanol RS710, manufactured by Toho Chemical Industry Co., Ltd.), ammonium polyacrylate (average molecular weight: 7900) and polishing compositions (a-1 to a-3 and b-) 1-b-3) were prepared. In that case, it diluted with the pure water so that solid content of a cerium oxide might be 1 weight% in polishing composition. Nonionic phosphorus-containing surfactant and poly (ammonium acrylate) (anionic surfactant) are listed in Table 1 in terms of% by weight based on the polishing composition.

  The polishing composition (a-1) was prepared by adjusting the aqueous sol (A-1) to a cerium oxide concentration of 1% by weight and using a nonionic phosphorus-containing surfactant (trade name: Phosphanol RP710). It was produced by adding 0.3% by weight in the product.

  The polishing composition (a-2) was prepared by adjusting the aqueous sol (A-2) to a cerium oxide concentration of 1% by weight and using a nonionic phosphorus-containing surfactant (trade name: Phosphanol RP710). It was manufactured by adding 0.01% by weight in the product and 0.3% by weight of ammonium polyacrylate in the polishing composition.

The polishing composition (a-3) was prepared by adjusting the aqueous sol (A-2) to a cerium oxide concentration of 1% by weight and using a nonionic phosphorus-containing surfactant (trade name: Phosphanol RS710). It was manufactured by adding 0.01% by weight in the product and 0.3% by weight of ammonium polyacrylate in the polishing composition.
The polishing composition (a-4) was prepared by adjusting the aqueous sol (A-2) to a cerium oxide concentration of 1% by weight and using a nonionic phosphorus-containing surfactant (trade name: Phosphanol RS710). It was produced by adding 0.3% by weight in the product.

  The polishing composition (b-1) was produced by adjusting the aqueous sol (A-1) to a cerium oxide concentration of 1% by weight.

  The polishing composition (b-2) was prepared by adjusting the aqueous sol (A-1) to a cerium oxide concentration of 1% by weight and adding 0.3% by weight of ammonium polyacrylate in the polishing composition. .

The polishing composition (b-3) was prepared by adjusting the aqueous sol (A-2) to a cerium oxide concentration of 1% by weight and adding 0.3% by weight of ammonium polyacrylate in the polishing composition. .
Polishing of the prepared polishing composition was performed as follows.

Polishing machine (Technorise Co., Ltd.),
Abrasive cloth: Polished cloth IC-1000 / suba400 (made by Rodel Nitta Co., Ltd.)
Object to be polished: plasma CVD silicon oxide film, CVD silicon nitride film on silicon wafer,
Rotational speed: 150rpm
Polishing pressure: 333 g / cm ²
Polishing time: 4 minutes.

  The polishing rate of the silicon oxide film and the silicon nitride film was determined by measuring the film thickness before and after polishing with a film thickness meter NANOSPEC (manufactured by NANOMETORICS). Further, the ratio of the polishing rates of the silicon oxide film and the silicon nitride film was obtained.

In Table 1, the polishing rate of the silicon oxide film is indicated by A (Å / min), the polishing rate of the silicon nitride film is indicated by B (Å / min), and (the polishing rate of the silicon oxide film) / (of the silicon nitride film) The ratio of the polishing rate was indicated by A / B.
[Table 1]
Table 1
―――――――――――――――――――――――――――――――――
Polishing composition A B A / B
―――――――――――――――――――――――――――――――――
a-1 2469 77 35
a-2 1860 55 34
a-3 2218 62 36
a-4 1870 43 44
b-1 3539 3215 1
b-2 983 39 25
b-3 1101 40 28
―――――――――――――――――――――――――――――――――
Although the polished surface was visually observed, none of the polished surfaces polished with the polishing compositions (a-1) to (a-4) and (b-1) to (b-3) showed any defects. .

  Comparing the polishing compositions a-1 and a-4 with b-1, the polishing compositions a-1 and a-4 to which the nonionic phosphorus-containing surfactant was added were polished with silicon oxide / silicon nitride. It can be seen that the speed ratio is significantly improved, and the polishing composition a-4 has a higher polishing speed ratio of silicon oxide / silicon nitride.

Further, polishing compositions a-2 and a-3 to which a nonionic phosphorus-containing surfactant and ammonium polyacrylate were added were used as polishing compositions b-2 and b-3 to which only ammonium polyacrylate was added. In comparison, it can be seen that the polishing rate ratio of silicon oxide / silicon nitride is high and the polishing rate of silicon oxide is twice or more faster.
Thus, the polishing composition to which the nonionic phosphorus-containing surfactant is added is a polishing composition having a high polishing rate selection ratio of the silicon oxide film / silicon nitride film and a high polishing rate of the silicon oxide film. Therefore, the shallow trench isolation can be efficiently formed with the polishing composition suitable for the planarization process of the substrate surface in the manufacturing process of the semiconductor element, particularly the formation process of the shallow trench isolation.

  A polishing composition comprising an aqueous sol containing cerium oxide particles and a nonionic phosphorus-containing surfactant is suitable for a flattening step of a substrate surface in a manufacturing process of a semiconductor element, particularly a forming process of shallow trench isolation.

Claims (4)

A polishing composition comprising an aqueous sol containing cerium oxide particles and a nonionic phosphorus-containing surfactant. The polishing composition according to claim 1, further comprising an anionic surfactant. The polishing according to claim 1 or 2, wherein the nonionic phosphorus-containing surfactant is at least one phosphate ester selected from the group consisting of a phosphate monoester, a phosphate diester, and a phosphate triester. Composition. Anionic surfactants include polyacrylic acid ammonium salt, polymethacrylic acid ammonium salt, ammonium oleate, ammonium lauryl sulfate, lauryl sulfate triethanolamine, polyoxyethylene lauryl ether ammonium sulfate, sodium polyacrylate, sodium polymethacrylate, The polishing according to any one of claims 1 to 3, which is at least one anionic surfactant selected from the group consisting of sodium oleate, sodium lauryl sulfate, and sodium polyoxyethylene lauryl ether sulfate. Composition.