POLISHING LIQUID COMPOSITION

Abstract

Provided is a polishing composition capable of improving polishing selectivity and reducing polishing unevenness while increasing polishing rate.

The present disclosure relates to a polishing composition containing; cerium oxide particles A; a polysaccharide B having a weight average molecular weight of 800 or more and 2800 or less; and water.

Claims

1. A polishing composition, comprising: cerium oxide particles A; a polysaccharide B having a weight average molecular weight of 800 or more and 2800 or less; and water.

2. The polishing composition according to claim 1, for use in polishing a silicon oxide film.

3. The polishing composition according to claim 1, wherein the polysaccharide B is a water-soluble dietary fiber.

4. The polishing composition according to claim 1, wherein a content of the polysaccharide B is 0.1 mass % or more and 2.5 mass % or less.

5. The polishing composition according to claim 1, wherein a ratio B/A of the content of the polysaccharide B to a content of the cerium oxide particles A is 0.01 or more and 20 or less.

6. The polishing composition according to claim 1, further comprising a compound C having an anionic group.

7. The polishing composition according to claim 6, wherein the compound C is a monovalent carboxylic acid.

8. The polishing composition according to claim 7, wherein the compound C is at least one selected from levulinic acid, propionic acid, vanillic acid, p-hydroxybenzoic acid, and formic acid.

9. The polishing composition according to claim 1, wherein a pH of the polishing composition is 4.0 or more and 9.0 or less.

10. The polishing composition according to claim 1, wherein the polishing composition is composed of a first liquid in which the cerium oxide particles A are mixed in water and a second liquid in which the polysaccharide B is mixed in water, and the first liquid and the second liquid are mixed in use.

11. A method for producing a semiconductor substrate, comprising polishing a substrate to be polished using the polishing composition according to claim 1.

12. A method for polishing a substrate, comprising polishing a substrate to be polished using the polishing composition according to claim 1, wherein the substrate to be polished is a substrate for producing a semiconductor substrate.

13. (canceled)

Description

EXAMPLES

1. Preparation of Polishing Compositions (Examples 1-23 and Comparative Examples 1-11)

[0129] Water, abrasive grains (particles A), and additives (polysaccharide B and compound C) were mixed in the proportion of Tables 1-1, 1-2 and 2 below to obtain polishing compositions of Examples 1-23 and Comparative Examples 1-11. The pH of the polishing compositions was adjusted using a 0.1 N ammonium aqueous solution.

[0130] The particles A used were colloidal ceria (ZENUS HC90 manufactured by Solvay Special Chem Japan, Ltd. (previously Anan Kasei Co., Ltd.), average primary particle diameter: 99 nm, BET specific surface area: 8.4 m.sup.2/g), amorphous ceria (baked pulverized ceria GPL-C1010, manufactured by SHOWA DENKO K.K., average primary particle diameter: 70 nm, BET specific surface area: 11.8 m.sup.2/g), ceria-coated silica (average primary particle diameter: 92.5 nm, BET specific surface area: 35.5 m.sup.2/g) and cerium hydroxide (average primary particle diameter: 5 nm, BET specific surface area: 165 m.sup.2/g).

[0131] The compounds C used were ammonium polyacrylate (weight average molecular weight: 21,000), citric acid, levulinic acid, propionic acid, vanillic acid, p-hydroxybenzoic acid, and formic acid.

[0132] The polysaccharides B used were as follows.

[0133] B1: indigestible glucan [trade name: Fit Fiber (registered trademark) #80 manufactured by NIHON SHOKUHIN KAKO CO., LTD., water-soluble dietary fiber, branched structure]

[0134] B2: polydextrose [trade name: Litesse (registered trademark) III manufactured by DuPont, water-soluble dietary fiber, branched structure, a condensate of glucose/sorbitol/citric acid (89/9/11)]

[0135] B3: polydextrose [trade name: STA-LITE (registered trademark) III manufactured by Tate & Lyle, branched structure, a condensate produced by thermal polymerization of D-glucose in the presence of sorbitol and phosphoric acid]

[0136] B4: -cyclodextrin [cyclic oligosaccharide, structure: six glucoses]

[0137] B5: pullulan [tradename: PULLULAN manufactured by FUJIFILM Wako Pure Chemical Corporation, straight-chain structure]

[0138] B6: dextrin [tradename: Sun Deck #300 manufactured by Sanwa Starch Co., Ltd., branched structure]

[0139] The pH of the polishing compositions, the average primary particle diameter and BET specific surface area of the particles A were measured by methods below. Tables 1-1 and 1-2 show the measurement results.

[0140] (a) pH Measurement of Polishing Composition

[0141] The pH value of each polishing composition at 25 C. was measured using a pH meter (HM-30G manufactured by DKK-TOA CORPORATION) and was read on the pH meter one minute after dipping an electrode of the pH meter into the polishing composition.

[0142] (b) Average Primary Particle Diameter of Particles A

[0143] The average primary particle diameter (nm) of the particles A was calculated using a specific surface area S (m.sup.2/g) obtained by the following BET (nitrogen adsorption) method, with the true density of the ceria particles set as 7.2 g/cm.sup.3.

[0144] (c) Method for Measuring BET Specific Surface Area of Particles A

[0145] A dispersion liquid of the ceria particles A was dried with hot air at 120 C. for three hours and the resultant was pulverized in an agate mortar to obtain a sample. The sample obtained was dried immediately before measurement in an atmosphere at 120 C. for 15 minutes. Then, the specific surface area S (m.sup.2/g) was measured by the nitrogen adsorption (BET) method using a specific surface area measuring device (micromeritics automatic specific surface area measuring device, FlowSorb III 2305 manufactured by Shimadzu Corporation).

2. Evaluation of Polishing Compositions (Examples 1-23 and Comparative Examples 1-11)

[0146] [Production of Specimen]

[0147] A silicon oxide film having a thickness of 2000 nm was formed on one side of a silicon wafer by a TEOS-plasma CVD method, and a 40 mm40 mm square piece was cut out from the silicon oxide film to prepare a specimen of the silicon oxide film.

[0148] Similarly, a silicon nitride film having a thickness of 300 nm was formed on one side of a silicon wafer by a CVD method, and a 40 mm40 mm square piece was cut out from the silicon nitride film to prepare a specimen of the silicon nitride film.

[0149] [Measurement of Polishing Rate for Silicon Oxide Film (Film to be Polished)]

[0150] MA-300 manufactured by Musashino Denshi Co., Ltd. (platen diameter: 300 mm) was used as a polishing device. A rigid urethane pad IC-1000/Sub400 manufactured by Nitta Haas Incorporated was used as a polishing pad. The polishing pad was attached onto the platen of the polishing device. The specimen was set in a holder, and the holder was placed on the polishing pad so that the surface of the specimen on which the silicon oxide film was formed would face downward (so that the silicon oxide film would face the polishing pad). Further, a weight was placed on the holder so that a load applied to the specimen would be 300 g weight/cm.sup.2. The specimen of the silicon oxide film was polished by rotating both of the platen and the holder in the same rotation direction at 90 r/min for one minute while dropping the polishing composition onto the center of the platen, on which the polishing pad was attached, at a rate of 50 mL/min. After polishing, the specimen was washed with ultrapure water and dried, followed by measurement using an optical interference-type film thickness measurement device described below.

[0151] The thicknesses of the silicon oxide film before and after polishing were measured using an optical interference-type film thickness measurement device (Lambda Ace VM-1000 manufactured by SCREEN Semiconductor Solutions Co., Ltd.). The polishing rate for the silicon oxide film was calculated from the formula below. Tables 1-1, 1-2 and 2 show the results.

Polishing rate for silicon oxide film (/min)=[Thickness of silicon oxide film before polishing ()Thickness of silicon oxide film after polishing ()]/Polishing time (min)

[0152] [Measurement of Polishing Rate for Silicon Nitride Film (Polishing Stopper Film)]

[0153] The polishing and thickness measurement of the silicon nitride film were performed in the same manner as in [Measurement of polishing rate for silicon oxide film] except for the use of the silicon nitride film instead of the silicon oxide film as a specimen. The polishing rate for the silicon nitride film was calculated from the formula below. Tables 1-1, 1-2 and 2 show the results.

Polishing rate for silicon nitride film (/min)=[Thickness of silicon nitride film before polishing ()Thickness of silicon nitride film after polishing ()]/Polishing time (min)

[0154] [Polishing Rate Ratio]

[0155] The ratio of the polishing rate for the silicon oxide film with respect to the polishing rate for the silicon nitride film is defined as a polishing rate ratio, and calculated from the formula below. Tables 1-1, 1-2 and 2 show the results. The larger value of the polishing rate ratio indicates higher polishing selectivity.

Polishing rate ratio=Polishing rate for silicon oxide film (/min)/polishing rate for silicon nitride film (/min)

[0156] [Method for Evaluating Polishing Unevenness]

[0157] The following evaluation method was used to measure the number of unevenness on the specimen of the silicon nitride film after polishing. First, the specimen of the silicon nitride film was photographed using COOLPIX S3700 manufactured by Nikon Corporation with the following settings.

[0158] ISO sensitivity: 400

[0159] Image mode: 2M (16001200)

[0160] White balance: Fluorescent

[0161] AF-area selection: Center

[0162] AF mode: AF-S single AF

[0163] AF-assist illuminator: Off

[0164] Electronic zoom: Off

[0165] Macro: ON

[0166] Using image analysis software WinROOF2013 manufactured by MITANI Corporation, the number of polishing unevenness in the photograph was measured under the following conditions.

[0167] The standard unit of measurement was set to 1 pixel. The photograph taken was monochromated, and a square area of 514514 pixels inside the wafer was designated as an analysis area (hereinafter, referred to as a designated area) by trimming. Then, the 256-level gray scale of the inside of the designated area (actual area: 263952 pixels) was reversed to emphasize a portion where polishing unevenness was occurred for easy recognition of the polishing unevenness, and the emphasized portion was binarized with threshold of 80 to 184 and transparency of 127 using a function of the software of Binarization with two thresholds. Then, the shape features of the binary region were measured, and an uneven portion having different chromaticities was counted as the number of polishing unevenness. Tables 1-1, 1-2 and 2 show the measurement results.

[0168] [Evaluation of Stability]

[0169] The pH of the polishing compositions of Examples 13-23 after one month of still standing at 60 C. was measured. Table 2 shows the measurement results. The polishing composition that retained the polishing performance after one month of still standing can be judged as having favorable storage stability.

TABLE-US-00001 TABLE 1-1 Polishing composition Polysaccharide B Weight Particles A average Content Content molecular Type mass % Type mass % weight Ex. 1 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Ex. 2 Colloidal ceria 0.5 B2 Polydextrose 1.0 1400 Ex. 3 Colloidal ceria 0.5 B1 Indigestible glucan 1.5 2530 Ex. 4 Colloidal ceria 0.5 B1 Indigestible glucan 0.5 2530 Ex. 5 Colloidal ceria 0.5 B3 Polydextrose 1.0 1430 Comp. Ex. 1 Colloidal ceria 0.5 Comp. Ex. 2 Colloidal ceria 0.5 B4 -Cyclodextrin 1.0 270 Comp. Ex. 3 Colloidal ceria 0.5 B5 Pullulan 1.0 280000 Comp. Ex. 4 Colloidal ceria 0.5 B6 Dextrin 1.0 2950 Comp. Ex. 5 Cerium 0.5 B1 Indigestible glucan 1.0 2530 hydroxide Comp. Ex. 6 Cerium 0.5 hydroxide Ex. 6 Ceria-coated 0.5 B1 Indigestible glucan 1.0 2530 silica Comp. Ex. 7 Ceria-coated 0.5 silica Ex. 12 Amorphous ceria 0.5 B2 Polydextrose 1.0 1400 Comp. Ex. 11 Amorphous ceria 0.5 Evaluation results Polishing Polishing Polishing Polishing composition rate for rate for rate ratio Compound C silicon silicon [silicon oxide Content oxide film nitride film film/silicon Polishing Type mass % pH [/min] [/min] nitride film] uneveness Ex. 1 6.0 7708 331 23 0 Ex. 2 6.0 6997 368 19 0 Ex. 3 6.0 6821 311 22 0 Ex. 4 6.0 7922 381 21 0 Ex. 5 6.0 6821 325 21 0 Comp. Ex. 1 6.0 7341 1570 5 0 Comp. Ex. 2 6.0 6822 515 13 10 Comp. Ex. 3 6.0 1100 210 5 0 Comp. Ex. 4 6.0 5817 396 15 3 Comp. Ex. 5 6.0 143 34 4 0 Comp. Ex. 6 6.0 3956 945 4 0 Ex. 6 6.0 3808 115 33 0 Comp. Ex. 7 6.0 3480 614 6 0 Ex. 12 6.0 5201 294 18 0 Comp. Ex. 11 6.0 5412 1455 4 0

TABLE-US-00002 TABLE 1-2 Polishing composition Polysaccharide B Weight Particles A average Content Content molecular Compound C Type mass % Type mass % weight Type Ex. 7 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Comp. Ex. 8 Colloidal ceria 0.5 Ex. 8 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Ammonium polyacrylate Ex. 9 Colloidal ceria 0.5 B2 Polydextrose 1.0 1400 Ammonium polyacrylate Ex. 10 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Citric acid Comp. Ex. 9 Colloidal ceria 0.5 Ammonium polyacrylate Ex. 11 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Ammonium polyacrylate Comp. Ex. 10 Colloidal ceria 0.5 Ammonium polyacrylate Evaluation results Polishing composition Polishing Polishing Polishing Compound rate for rate for rate ratio C silicon silicon [silicon oxide Content oxide film nitride film film/silicon Polishing mass % pH [/min] [/min] nitride film] unevenness Ex. 7 8.0 7036 222 32 0 Comp. Ex. 8 8.0 6618 1498 4 0 Ex. 8 0.0015 8.0 4098 117 35 0 Ex. 9 0.0015 8.0 4525 112 40 0 Ex. 10 0.0015 8.0 4210 121 35 0 Comp. Ex. 9 0.0015 8.0 3765 548 7 0 Ex. 11 0.0015 4.5 5254 114 46 0 Comp. Ex. 10 0.0015 4.5 4005 364 11 0

TABLE-US-00003 TABLE 2 Polishing composition Polysaccharide B Weight Particles A average Compound C Content Content molecular Content Type mass % Type mass % weight Type mass % pH Ex. 13 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 4.5 Ex. 14 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Levulinic acid 0.001 4.5 Ex. 15 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Levulinic acid 0.1 4.5 Ex. 16 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Levulinic acid 0.01 4.5 Ex. 17 Amorphous ceria 0.5 B1 Indigestible glucan 1.0 2530 Levulinic acid 0.01 4.5 Ex. 18 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Propionic acid 0.01 4.5 Ex. 19 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2350 Vanillic acid 0.01 4.5 Ex. 20 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 p-Hydroxybenzoic acid 0.01 4.5 Ex. 21 Colloidal ceria 0.5 B1 Indigestible glucan 1.0 2530 Formic acid 0.01 4.5 Ex. 22 Colloidal ceria 0.5 B2 Polydextrose 1.0 1400 Levulinic acid 0.01 4.5 Ex. 23 Colloidal ceria 0.5 B2 Polydextrose 1.0 1400 Formic acid 0.01 4.5 Evaluation results Polishing Polishing Polishing rate for rate for rate ratio Stability silicon oxide silicon [silicon oxide 60 C. film nitride film film/silicon Polishing Initial After lapse of [/min] [/min] nitride film] unevenness stage one month Ex. 13 6989 348 20 0 4.5 3.8 Ex. 14 7139 335 21 0 4.5 4.0 Ex. 15 6738 222 30 0 4.5 4.4 Ex. 16 5360 156 34 0 4.5 4.2 Ex. 17 4283 148 29 0 4.5 4.4 Ex. 18 6742 274 25 0 4.5 4.2 Ex. 19 7211 235 31 0 4.5 4.2 Ex. 20 6234 391 16 0 4.5 4.2 Ex. 21 6946 296 23 0 4.5 4.1 Ex. 22 7287 188 39 0 4.5 4.2 Ex. 23 6942 171 41 0 4.5 4.1

[0170] As shown in Tables 1-1, 1-2 and 2, the polishing compositions of Examples 1-23 containing a predetermined polysaccharide B improved the polishing selectivity and reduced the polishing unevenness while increasing the polishing rate. The polishing compositions of Examples 8-11 containing ammonium polyacrylate or citric acid as the compound C further improved the polishing selectivity. The polishing compositions of Examples 14-23 containing levulinic acid, propionic acid, vanillic acid, p-hydroxybenzoic acid, or formic acid as the compound C had favorable storage stability.

INDUSTRIAL APPLICABILITY

[0171] The polishing composition of the present disclosure is useful in a method for producing a high density or high integration semiconductor substrate.