POLISHING COMPOSITION FOR SILICON OXIDE FILM

Abstract

Provided is a polishing composition for a silicon oxide film that can improve the speed of polishing a silicon oxide film. In one or more embodiments, a polishing composition for a silicon oxide film contains: water; a cerium oxide particle; and a compound having in its molecule an amino group and at least one acid group selected from a sulfonic acid group and a phosphonic acid group. In the polishing composition, [the number of moles of the acid group contained in the compound]/[total surface area of the cerium oxide particle] is in a range from 1.6×10.sup.−5 mol/m.sup.2 to 5.0×10.sup.−2 mol/m.sup.2.

Claims

1. A polishing composition for a silicon oxide film, comprising: water; a cerium oxide particle; and a compound having in its molecule an amino group and at least one acid group selected from a sulfonic acid group and a phosphonic acid group, wherein a ratio of the number of moles of the acid group contained in the compound to a total surface area of the cerium oxide particle ([the number of moles of the acid group contained in the compound]/[total surface area of the cerium oxide particle]) is in a range from 1.6×10.sup.−5 mol/m.sup.2 to 5.0×10.sup.−2 mol/m.sup.2.

2. The polishing composition according to claim 1, wherein an average primary particle diameter of the cerium oxide particle calculated by a BET method is in a range from 15 nm to 300 nm.

3. The polishing composition according to claim 1, wherein a content of the cerium oxide particle in the polishing composition is in a range from 0.001 mass % to 1 mass %.

4. The polishing composition according to claim 1, wherein the compound is sulfamic acid or aminomethylphosphonic acid.

5. The polishing composition according to claim 1, wherein a content of the compound in the polishing composition is in a range from 0.001 mass % to 0.15 mass %.

6. The polishing composition according to claim 1, wherein a pH of the polishing composition is in a range from 3.0 to 8.0.

7. A use of a composition in polishing a silicon oxide film, the composition comprising: water; a cerium oxide particle; and a compound having in its molecule an amino group and at least one acid group selected from a sulfonic acid group and a phosphonic acid group, wherein a ratio of the number of moles of the acid group contained in the compound to a total surface area of the cerium oxide particle ([the number of moles of the acid group contained in the compound]/[total surface area of the cerium oxide particle]) is in a range from 1.6×10.sup.−5 mol/m.sup.2 to 5.0×10.sup.−2 mol/m.sup.2.

8. A method for producing a semiconductor substrate, comprising polishing a silicon oxide film using the polishing composition according to claim 1.

9. A method for polishing a semiconductor substrate, comprising polishing a silicon oxide film using the polishing composition according to claim 1.

Description

EXAMPLES

1. Preparation of Polishing Composition

[0094] Water, an abrasive grain (ceria particle), and sulfamic acid or aminomethylphosphonic acid were mixed in the proportion of Table 1 below, and thereby each polishing composition was obtained. The pH of the polishing composition was adjusted using 1N hydrochloric acid aqueous solution.

[0095] Colloidal ceria (BET equivalent particle diameter 69 nm, BET specific surface area 12.1 m.sup.2/g) and baked pulverized ceria (BET equivalent particle diameter 70 nm, BET specific surface area 11.8 m.sup.2/g) were used as ceria particles.

[0096] The pH of the polishing composition, the BET equivalent particle diameter of the ceria particle, and the BET specific surface area of the ceria particle were measured by the following methods.

[0097] (a) pH Measurement of Polishing Composition

[0098] The pH value of the polishing composition at 25° C. was measured using a pH meter (HM-30G, DKK-TOA CORPORATION) and was read on the pH meter one minute after dipping an electrode into the polishing composition.

[0099] (b) BET Equivalent Particle Diameter of Ceria Particle

[0100] The BET equivalent particle diameter (nm) of the ceria particle was calculated using a specific surface area S (m.sup.2/g) obtained by the following BET (nitrogen adsorption) method, with a specific gravity of the ceria particle set as 7.2 g/cm.sup.3.

[0101] (c) Method for Measuring BET Specific Surface Area of Ceria Particle

[0102] A ceria particle dispersion liquid was dried by hot air at 120° C. for three hours and the resultant was pulverized in an agate mortar, and thereby a sample was obtained. The sample thus obtained was dried in an atmosphere at 120° C. for 15 minutes immediately before measuring the specific surface area. 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 Analyzer, FlowSorb III 2305 manufactured by Shimadzu Corporation).

2. Evaluation of Polishing Compositions (Examples 1-18, Comparative Examples 1-3, Reference Examples 1-2)

[0103] [Production of Specimen]

[0104] An oxide film test specimen was obtained by cutting out a 40 mm×40 mm square piece from a 2000-nm-thick silicon oxide film (oxide film) formed on one side of a silicon wafer by a TEOS-plasma CVD method.

[0105] [Measurement of Polishing Speed for Oxide Film]

[0106] “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 test specimen was set in a holder, and the holder was placed on the polishing pad so that the surface of the test specimen on which a silicon oxide film was formed would face downward (so that the oxide film would face the polishing pad). Further, a weight was placed on the holder so that a load applied to the test specimen would be 300 g weight/cm.sup.2. The oxide film test specimen was polished by rotating both of the platen and the holder in the same rotation direction at 90 r/min for two minutes while dropping the polishing composition onto the center of the platen, on which the polishing pad was attached, at a speed of 50 mL/min. After polishing, the oxide film test specimen was washed with ultrapure water and dried, followed by measurement using a spectroscopic reflectometer described below.

[0107] The thicknesses of the oxide film before and after polishing were measured using a spectroscopic reflectometer (“Lambda Ace VM-1000” manufactured by SCREEN Semiconductor Solutions Co., Ltd.). The polishing speed for the oxide film was calculated from the formula below. Table 1 below shows the polishing speed for the oxide film, and the speed ratio relative to the polishing speed in Comparative Example 1, 2 or 3 in which neither sulfamic acid nor aminomethylphosphonic acid was used.

Polishing speed for oxide film (Å/min)=[Thickness of oxide film before polishing (Å)−Thickness of oxide film after polishing (Å)]/Polishing time (min)

TABLE-US-00001 TABLE 1 Speed ratio relative to Acid group/ polishing Particle Particle Polishing composition concentration Acid/Particle surface area speed without Particle [mass %] pH mass ratio [mol/m.sup.2] [Å/min] acid (0%) Sulfamic acid concentration [mass %] Com. Ex. 1 Colloidal ceria 0.5 0.00 4.5 0 0.0E+00 1,799 1.0 Ex. 1 Colloidal ceria 0.5 0.05 4.5 0.1 8.5E−05 2,656 1.5 Ex. 2 Colloidal ceria 0.5 0.10 4.5 0.2 1.7E−04 4,451 2.5 Ex. 3 Colloidal ceria 0.5 0.15 4.5 0.3 2.6E−04 3,826 2.1 Ex. 4 Colloidal ceria 0.5 0.30 4.5 0.6 5.1E−04 3,886 2.2 Ref. Ex. 1 Colloidal ceria 0.5 0.10 2.5 0.2 1.7E−04 872 0.5 Ex. 5 Colloidal ceria 0.5 0.10 3.5 0.2 1.7E−04 2,202 1.2 Ex. 2 Colloidal ceria 0.5 0.10 4.5 0.2 1.7E−04 4,451 2.5 Ex. 6 Colloidal ceria 0.5 0.10 5.5 0.2 1.7E−04 4,948 2.8 Ex. 7 Colloidal ceria 0.5 0.10 6.5 0.2 1.7E−04 3,006 1.7 Ex. 8 Colloidal ceria 0.5 0.10 7.5 0.2 1.7E−04 2,400 1.3 Ref. Ex. 2 Colloidal ceria 0.5 0.10 8.5 0.2 1.7E−04 486 0.3 Com. Ex. 2 Colloidal ceria 0.1 0 4.5 0 0.0E+00 1,417 1.0 Ex. 9 Colloidal ceria 0.1 0.01 4.5 0.1 8.5E−05 3,162 2.2 Ex. 10 Colloidal ceria 0.1 0.03 4.5 0.3 2.6E−04 3,408 2.4 Ex. 11 Colloidal ceria 0.1 0.05 4.5 0.5 4.3E−04 3,347 2.4 Ex. 12 Colloidal ceria 0.1 0.10 4.5 1 8.5E−04 3,285 2.3 Ex. 13 Colloidal ceria 0.1 0.15 4.5 1.5 1.3E−03 3,164 2.2 Ex. 14 Colloidal ceria 0.1 0.3 4.5 3 2.6E−03 2,171 1.5 Com. Ex. 3 Baked 0.5 0 6.0 0 0.0E+00 6,961 1.0 pulverized ceria Ex. 15 Baked 0.5 0.01 6.0 0.02 1.7E−05 9,139 1.3 pulverized ceria Ex. 16 Baked 0.5 0.03 6.0 0.06 5.2E−05 8,114 1.2 pulverized ceria Ex. 17 Baked 0.5 0.05 6.0 0.1 8.7E−05 8,381 1.2 pulverized ceria Aminomethyl phosphonic acid concentration [mass %] Com. Ex. 1 Colloidal ceria 0.5 0.00 4.5 0 0.0E+00 1,799 1.0 Ex. 18 Colloidal ceria 0.5 0.15 4.5 0.3 2.2E−04 3,810 2.1 * Ex.: Example, Com. Ex.: Comparative Example, Ref. Ex: Reference Example

[0108] As shown in Table 1, Examples 1-8 in which colloidal ceria particles and sulfamic acid were used in combination resulted in a higher polishing speed than Comparative Example 1 in which sulfamic acid was not used. Similarly, Examples 9-14 in which colloidal ceria particles and sulfamic acid were used in combination resulted in a higher polishing speed than Comparative Example 2 in which sulfamic acid was not used. Further, Examples 15-17 in which baked pulverized ceria particles and sulfamic acid were used in combination resulted in a higher polishing speed than Comparative Example 3 in which sulfamic acid was not used. Moreover, Example 18 in which colloidal ceria particles and aminomethylphosphonic acid were used in combination resulted in a higher polishing speed than Comparative Example 1 in which aminomethylphosphonic acid was not used.

INDUSTRIAL APPLICABILITY

[0109] As explained above, in one or more embodiments, the polishing composition of the present disclosure is useful in a method for producing a high density or high integration semiconductor substrate.