# US 12,760,202 B2 · Polishing composition

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- Number: US 12,760,202 B2
- Document ID: US12760202B2
- Status: Granted
- Kind: B2
- Application number: 17/732,242
- Filed: 2022-04-28
- Published: 2022-11-24
- Granted: 2026-10-13
- Earliest claimed: 2021-05-24
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Shin-Etsu Chemical Co., Ltd.
- Inventors: Naoki Yarita; Daijitsu Harada; Harunobu Matsui; Masaki Takeuchi
- Web page: https://patentgrep.com/patent/US12760202B2

## CPC

- C09G 1/02: containing abrasives or grinding agents {(abrasives as such C09K3/14; polishing of semi-conductors H10P52/40)}
- C09K 3/1409: {Abrasive particles per se (preparation of diamond C01B32/25)}
- C09G: POLISHING COMPOSITIONS (French polish C09F11/00); SKI WAXES
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A polishing composition including a colloidal silica containing colloidal silica particles, a pH adjusting agent, and a chelating agent provides a substrate that has a surface having a high flatness, low defects and a low surface roughness with low cost and high productivity, and a substrate having high surface quality suitable as a substrate for mask blanks such as a glass substrate containing SiO2 as a main component, particularly, as a substrate for mask blanks used in EUVL.

## Claims

### Claim 1

A polishing composition comprising
a colloidal silica comprising colloidal silica particles, a pH adjusting agent, and a chelating agent,
wherein
the colloidal silica particles contain secondary particles formed by association of primary particles,
the primary particles have an average primary particle size DA1 of not less than 5 nm and not more than 50 nm that is calculated from a specific surface area measured by a gas absorption method,
the colloidal silica particles have a degree of association P32 DA2/DA1 of not more than 1.8 calculated by dividing a secondary particle size DA2 by the average primary particle size DA1, DA2 being measured by a dynamic light scattering method, and
a maximum of an auto-correlation function G2(f) is not less than 1.40 in a region of frequency f of not less than 0.001 MHz and not more than 1 MHz, G2(f) being obtained by variable transformation of G2 (t) with “frequency f=1/τ”, wherein G2(τ) is calculated, from I(t) representing time dependency of intensity of scattered light that is obtained by measuring translational motion of the colloidal silica particles existing in the polishing composition measured by a dynamic light scattering method using laser, by the following expression (1):
G
2
(
τ
)
=
〈
I
⁡
(
t
)
·
I
⁡
(
t
+
τ
)
〉
〈
I
⁡
(
t
)
〉
2
=
(
∫
0
T
I
⁡
(
t
)
·
I
⁡
(
t
+
τ
)
⁢
dt
T
)
(
∫
0
T
I
⁡
(
t
)
⁢
dt
T
)
2
=
T
⁢
∫
0
T
I
⁡
(
t
)
·
I
⁡
(
t
+
τ
)
⁢
dt
(
∫
0
T
I
⁡
(
t
)
⁢
dt
)
2
(
1
)
wherein T is a measuring time of an intensity of scattered light, I(t) is an intensity of scattered light at an arbitrary time t, and I(t+τ) is an intensity of scattered light after a predetermined time τ has elapsed from the arbitrary time t.

### Claim 2 (depends on 1)

The polishing composition of claim 1 wherein the colloidal silica particles contained in the colloidal silica have the degree of association P=DA2/DA1 of not more than 1.3.

### Claim 3 (depends on 1)

The polishing composition of claim 1 wherein the colloidal silica particles existing in the polishing composition have a zeta potential of not less than −40 mV and not more than −5 mV.

### Claim 4 (depends on 1)

The polishing composition of claim 1 wherein the colloidal silica particles existing in the polishing composition have a polydispersity index of not more than 0.3.

### Claim 5 (depends on 1)

The polishing composition of claim 1 wherein the polishing composition comprises the colloidal silica particles of not less than 10 wt % and not more than 40 wt %.

### Claim 6 (depends on 1)

The polishing composition of claim 1 wherein the polishing composition comprises the pH adjusting agent of not less than 0.1 wt % and not more than 10 wt %.

### Claim 7 (depends on 1)

The polishing composition of claim 1 having a pH of not less than 8 and not more than 10.5.

### Claim 8 (depends on 1)

The polishing composition of claim 1 wherein the polishing composition comprises the chelating agent of not less than 0.1 wt % and not more than 10 wt %.

### Claim 9 (depends on 1)

The polishing composition of claim 1 for polishing a glass substrate containing SiO2 as a main component.

### Claim 10 (depends on 1)

The polishing composition of claim 1 wherein the chelating agent comprises citric acid.