CN-122003477-A - Titanium oxide-based chemical mechanical polishing composition for highly boron-doped silicon films

Abstract

The invention provides a chemical mechanical polishing composition comprising (a) a titanium oxide abrasive, (b) an oxidizing agent, and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less. The invention also provides a method of chemically-mechanically polishing a substrate, particularly a substrate comprising a boron-doped polysilicon layer on a surface of the substrate, using the composition.

Inventors

• A. Villani Calais
• B. Rice
• E. Napton
• T. S. Sackville
• HUANG HELIN
• W. Lemki

Assignees

• 恩特格里斯公司

Dates

Publication Date

20260508

Application Date

20240830

Priority Date

20230905

Claims (20)

1. 1. A chemical mechanical polishing composition comprising: (a) A titanium oxide abrasive, wherein the titanium oxide abrasive is substantially pure rutile titanium oxide; (b) Oxidizing agent, and (C) The water is used as the water source, Wherein the chemical mechanical polishing composition has a pH of about 7 or less.
2. 2. The polishing composition of claim 1, wherein the polishing composition has a pH of about 6 or less.
3. 3. The polishing composition of claim 1, wherein the polishing composition has a pH of about 5 or less.
4. 4. The polishing composition of claim 1, wherein the polishing composition comprises about 0.001 wt to about 10 wt percent of the titanium oxide abrasive.
5. 5. The polishing composition of claim 1, wherein the polishing composition comprises about 0.025 wt% to about 5 wt% of the titanium oxide abrasive.
6. 6. The polishing composition of claim 1, wherein the titanium oxide abrasive has an average particle size of about 10 nm to about 300 nm.
7. 7. The polishing composition of claim 1, wherein the titanium oxide abrasive has an average particle size of about 50 nm to about 150 nm.
8. 8. The polishing composition of claim 1, wherein the oxidizing agent is selected from the group consisting of potassium hydrogen persulfate, ammonium cerium nitrate, peroxides, periodates, iodates, persulfates, chlorates, chromates, permanganates, bromates, perbromates, ferrites, perrhenates, perruthenates, and combinations thereof.
9. 9. The polishing composition of claim 1, wherein the oxidizing agent is selected from the group consisting of permanganate, ceric ammonium nitrate, and combinations thereof.
10. 10. The polishing composition of claim 9, wherein the oxidizing agent is ceric ammonium nitrate.
11. 11. The polishing composition of claim 9, wherein the oxidizing agent is potassium permanganate.
12. 12. The polishing composition of claim 1, wherein the polishing composition comprises 1 wt to 20 wt% of the oxidizing agent.
13. 13. The polishing composition of claim 1, wherein the polishing composition further comprises iron ions.
14. 14. The polishing composition of claim 13, wherein the polishing composition comprises about 0.01 wt to about 1wt percent iron ions.
15. 15. The polishing composition of claim 1, wherein the polishing composition comprises substantially no iron ions.
16. 16. The polishing composition of claim 1, wherein the polishing composition further comprises about 1mM to about 100mM of an organic acid.
17. 17. The polishing composition of claim 16, wherein the organic acid is selected from the group consisting of maleic acid, citric acid, L-ascorbic acid, picolinic acid, malonic acid, and combinations thereof.
18. 18. The polishing composition of claim 1, wherein the polishing composition further comprises a buffer.
19. 19. The polishing composition of claim 18, wherein the buffer is selected from the group consisting of ammonium salts, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, amino acids, and combinations thereof.
20. 20. A method of chemically-mechanically polishing a substrate, comprising: (i) A substrate comprising a boron doped polysilicon layer is provided, (Ii) A polishing pad is provided and is configured to be disposed, (Iii) Providing a chemical mechanical polishing composition comprising: (a) About 0.001 wt to about 10wt percent of a titanium oxide abrasive, wherein the titanium oxide abrasive is substantially pure rutile titanium oxide; (b) Oxidizing agent, and (C) The water is used as the water source, Wherein the chemical-mechanical polishing composition has a pH of about 7 or less, (Iv) Contacting the substrate with the polishing pad and the chemical mechanical polishing composition, and (V) The polishing pad and the chemical mechanical polishing composition are moved relative to the substrate to abrade at least a portion of the substrate to polish the substrate.

Description

Titanium oxide-based chemical mechanical polishing composition for highly boron-doped silicon films Background Compositions and methods for planarizing or polishing a surface of a substrate are well known in the art. Polishing compositions (also known as polishing slurries) typically contain an abrasive material in a liquid carrier and are applied to a surface by contacting the surface with a polishing pad filled with the polishing composition. Typical abrasive materials include silica, ceria, alumina, zirconia, and tin oxide. The polishing composition is typically used in conjunction with a polishing pad (e.g., a polishing cloth or disk). Alternatively or in addition to being suspended in the polishing composition, the abrasive material can also be incorporated into the polishing pad. Boron doped polysilicon or boron-polysilicon alloys are increasingly used as patterned hard masks during the fabrication of advanced node memory devices such as Dynamic Random Access Memory (DRAM). Achieving high removal rates of this material by Chemical Mechanical Planarization (CMP) can be challenging due to the high boron content in the polysilicon material. In addition to requiring high removal rates of boron-polysilicon films, some memory device schemes also require very low removal rates of silicon nitride and/or silicon oxide that can serve as termination layers in the device film stack. This puts selectivity requirements during CMP. In addition, some memory device schemes also require medium to high removal rates of titanium nitride that may also be used in the fabrication of some memory devices. The ability to adjust the removal rate of boron doped polysilicon and/or titanium nitride relative to silicon oxide and/or silicon nitride would be a desirable feature of polishing compositions and methods useful in device fabrication. Accordingly, there remains a need in the art for polishing compositions and methods for polishing boron-polysilicon layers and titanium nitride layers, wherein the boron-polysilicon and titanium nitride layers have high removal rates and selectivities. The present invention provides such polishing compositions and methods. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein. Disclosure of Invention The invention provides a chemical mechanical polishing composition comprising (a) a titanium oxide abrasive, (b) an oxidizing agent, and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less. The invention further provides a method of chemically-mechanically polishing a substrate comprising (i) providing a substrate, (ii) providing a polishing pad, (iii) providing a chemical-mechanical polishing composition comprising (a) a titanium oxide abrasive, (b) an oxidizing agent, and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 7 or less, (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition, and (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate, thereby polishing the substrate. Detailed Description The invention provides a chemical mechanical polishing composition comprising (a) a titanium oxide abrasive, (b) an oxidizing agent, and (c) water, wherein the chemical mechanical polishing composition has a pH of about 7 or less. The polishing composition comprises a titanium oxide abrasive. As used herein, the terms "abrasive" and "abrasive particles" are used interchangeably and can refer to any dispersion of abrasive particles. In other words, the terms "abrasive" and "abrasive particles" refer to (i) multiple single types of abrasives or abrasive particles and/or (ii) multiple more than one type of abrasives or abrasive particles. Titanium oxide (i.e., titanium dioxide) exists in at least seven polymorphs, four of which exist in nature. The three most common natural forms of titanium oxide are rutile, anatase and brookite, with the rutile and anatase forms being those commonly obtained via synthesis. All forms of titanium oxide have the same empirical formula TiO 2, but each has a different crystal structure. The rutile form ("rutile") is the most thermally stable form of titanium oxide. The crystal structure of rutile is tetragonal, with four sides shared by the Ti-O octahedra. The anatase form ("anatase") has a tetragonal crystal structure similar to rutile, except that Ti-O octahedra share four corners instead of four sides. Anatase spontaneously converts to more stable rutile at temperatures above about 915 ℃. Brookite forms ("brookites") have an orthorhombic crystal structure that spontaneously converts to rutile at temperatures of about 750 ℃, the least common of the three common forms and are rarely used commercially. Numerous methods for preparing titanium oxides are known