Polishing liquid and chemical mechanical polishing method

Patent metadata

Field	Value
Publication number	US-11401442-B2
Application number	US-202016936526-A
Country	US
Kind code	B2
Filing date	Jul 23, 2020
Priority date	Mar 23, 2018
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

A polishing liquid is used for chemical mechanical polishing and includes colloidal silica; and an onium salt containing a cation, in which a content of the onium salt is more than 0.01% by mass, a zeta potential of the colloidal silica measured in a state where the colloidal silica is present in the polishing liquid is 15 mV or more, an electrical conductivity is 10 μS/cm or more, and a pH is 2 to 4.

First claim

What is claimed is:

1. A polishing liquid used for chemical mechanical polishing, the polishing liquid comprising:
colloidal silica wherein a degree of associated of the colloidal silica is 1 or more and 3 or less,
an onium salt containing a cation,
wherein the onium salt includes at least one selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraoctylammonium hydroxide, and tetrabutylphosphonium hydroxide,
a content of the onium salt is 0.05 to 1% by mass with respect to a total mass of the polishing liquid,
a zeta potential of the colloidal silica measured in a state where the colloidal silica is present in the polishing liquid is 15 mV or more,
an electrical conductivity is 10 μS/cm or more, and
a pH is 2 to 4.

2. The polishing liquid according to claim 1 , wherein the polishing liquid contains two or more kinds of the onium salts.

3. The polishing liquid according to claim 1 , wherein a concentration of iron ions is less than 1 ppm by mass.

4. The polishing liquid according to claim 1 , further comprising an anionic polymer compound.

5. The polishing liquid according to claim 4 , wherein a weight-average molecular weight of the anionic polymer compound is 2,000 to 50,000.

6. The polishing liquid according to claim 4 , wherein the anionic polymer compound includes at least one selected from the group consisting of a polyacrylic acid, a polymethacrylic acid, a copolymer containing a polyacrylic acid and a polymethacrylic acid, and a salt thereof.

7. The polishing liquid according to claim 1 ,
wherein, in a case where the polishing liquid is used for polishing silicon nitride and silicon oxide,
a ratio of a polishing speed for the silicon oxide to a polishing speed for the silicon nitride is 10 or more.

8. The polishing liquid according to claim 1 , further comprising a cationic surfactant or an amphoteric surfactant.

9. The polishing liquid according to claim 8 ,
wherein, in a case where the polishing liquid is used for polishing silicon oxide and polysilicon,
a ratio of a polishing speed for the silicon oxide to a polishing speed for the polysilicon is 10 or more.

10. The polishing liquid according to claim 1 , further comprising an anionic surfactant.

11. The polishing liquid according to claim 10 ,
wherein, in a case where the polishing liquid is used for polishing silicon oxide and polysilicon,
a ratio of a polishing speed for the silicon oxide to a polishing speed for the polysilicon is 0.25 to 1.5.

12. The polishing liquid according to claim 1 , further comprising an anionic polymer compound,
wherein the content of the onium salt is 0.09 to 1% by mass with respect to the total mass of the polishing liquid, and
a concentration of iron ions is less than 1 ppm by mass.

13. The polishing liquid according to claim 1 , further comprising an anionic polymer compound,
wherein the colloidal silica is consisting of one kind thereof,
the onium salt includes at least one selected from the group consisting of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylphosphonium hydroxide,
a weight-average molecular weight of the anionic polymer compound is 2,000 to 50,000,
the content of the onium salt is 0.09 to 1% by mass with respect to the total mass of the polishing liquid,
a content of the anionic polymer compound is 0.1 to 0.3% by mass with respect to the total mass of the polishing liquid,
a concentration of iron ions is less than 1 ppm by mass, and
the pH is 2 to 3.

14. A chemical mechanical polishing method comprising bringing a polishing target surface of a polishing target object into contact with a polishing pad while supplying the polishing liquid according to claim 1 to the polishing pad attached to a polishing platen, relatively moving the polishing target object and the polishing pad to polish the polishing target surface, and obtaining a polished polishing target object.

15. The chemical mechanical polishing method according to claim 14 , wherein the polishing target object includes silicon nitride and silicon oxide.

16. The chemical mechanical polishing method according to claim 15 , wherein the polishing target object further contains polysilicon.

Assignees

• Fujifilm Corp

Inventors

• Kamimura Tetsuya

Classifications

• H10P95/062 Primary

  involving a dielectric removal step · CPC title

• H10P52/402

  of semiconductor materials · CPC title

• H10P52/403

  of conductive or resistive materials · CPC title

• C09K3/1454

  Abrasive powders, suspensions and pastes for polishing · CPC title

• C09K3/14

  Anti-slip materials; Abrasives {(products specifically intended for the fabrication of abrasive tools, blocks or papers, or for operations of the kind of sand-blasting and barrelling B24B31/14, B24C1/00; polishing compositions containing abrasive or grinding agents C09G1/02; friction compositions for brakes or clutches F16D69/02; polishing of semi-conductors H10P52/40)} · CPC title