Method for fabricating semiconductor device

• US 20020192915A1
• Filed: 05/22/2002
• Published: 12/19/2002
• Est. Priority Date: 05/23/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kume, Satoshi, Wada, Yukihisa
• Granted Patent: US 6,613,636 B2
• Time in Patent Office: Days
• US Class Current: 438/305
• CPC Class Codes: H01L 21/31111 by chemical means
• CPC Class Codes: H01L 21/823864 with a particular manufacturing method of the gate sidewall spacers, e.g. double spacers, particular spacer material or shape

Abstract

On the sides of a gate electrode, layered-film sidewalls are formed which includes a first oxide film such as an NSG film or a TEOS film and a second oxide film such as a BPSG film or a PSG film. After the layered-film sidewalls are used as a mask for forming source and drain regions of a MIS transistor, the second oxide film of the sidewalls is selectively removed. At the removal, wet etching is performed with an aqueous solution containing hydrofluoric acid, and acetic acid or isopropyl alcohol. This makes etching selectivity between oxide films higher and removes only the upper second oxide film. As a result, in the formation of two types of oxide films which differ in their etching properties, the etching selectivity can be prevented from deteriorating.

Claims

1. A method for fabricating a semiconductor device having a MIS transistor provided with a gate insulating film on a semiconductor substrate and a gate electrode on the gate insulating film, the method including the steps of:

(a) forming, on the sides of the gate electrode, sidewalls including a first oxide film and a second oxide film which have different etching properties;

(b) implanting ions for forming source and drain regions using the sidewalls as a mask; and

(c) selectively removing the second oxide film by etching the sidewalls with a mixed solution containing hydrofluoric acid and an organic solution.

2. The method of claim 1, wherein in the step (a), an NSG film, a TEOS film or a plasma oxide film is formed as the first oxide film, and a BPSG film, a PSG film or a BSG film is formed as the second oxide film.

3. The method of claim 1, wherein in the step (c), the mixed solution is a solution having a mixture ratio defined by 0.1 to 5.0 weight percent of hydrofluoric acid, 0.1 to 5.0 weight percent of water and the remaining weight percent of acetic acid.

4. The method of claim 1, wherein in the step (c), the mixed solution is a solution having a mixture ratio defined by 0.1 to 5.0 weight percent of hydrofluoric acid, 0.1 to 5.0 weight percent of water and the remaining weight percent of isopropyl alcohol.

5. The method of claim 1, wherein the gate electrode is formed of polysilicon, polymetal or metal.

6. The method of claim 1, wherein the method further includes the step of cleaning the substrate with a hydrogen peroxide solution or an ozone solution after the step (c) and before a drying step.

7. The method of claim 6, wherein the hydrogen peroxide concentration in the hydrogen peroxide solution is in the range of 0.01 to 30.0 weight percent.

8. The method of claim 6, wherein the ozone concentration in the ozone solution is in the range of 0.1 to 150.0 ppm.

9. The method of claim 1, wherein the step (a) includes the sub-steps of:

forming the first oxide film on the top and sides of the gate electrode;

forming a nitride film on the first oxide film;

forming the second oxide film on the nitride film; and

etching back the second oxide film to form layered-film sidewalls constituted of a double-layered film made of the first oxide and nitride films substantially in L-shaped section and the second oxide film in sectoral section,

and in the step (c), double-layered-film sidewalls made of the first oxide and nitride films substantially in L-shaped section are formed on the sides of the gate electrode.

10. A method for fabricating a semiconductor device, including the steps of:

(a) forming, on a subsurate, a layered film including two types of oxide films which differ in their etching properties; and

(b) selectively removing the layered film by selective etching with a mixed solution containing hydrofluoric acid and an organic solution,

wherein in the step (b), the etching selectivity of one of the two oxide films with respect to the other is increased using the mixed solution.

11. The method of claim 10, wherein in the step (b), the mixed solution is a solution having a mixture ratio defined by 0.1 to 5.0 weight percent of hydrofluoric acid, 0.1 to 5.0 weight percent of water and the remaining weight percent of acetic acid.

12. The method of claim 10, wherein in the step (b), the mixed solution is a solution having a mixture ratio defined by 0.1 to 5.0 weight percent of hydrofluoric acid, 0.1 to 5.0 weight percent of water and the remaining weight percent of isopropyl alcohol.

14. The method of claim 13, wherein in the step (f), the hydrogen peroxide concentration in the hydrogen peroxide solution is selected in the range of 0.01 to 30.0 weight percent, while the ozone concentration in the ozone solution is selected in the range of 0.1 to 150.0 ppm.

13. A method for fabricating a semiconductor device having a MIS transistor, the method including the steps of:

(a) forming a gate oxide film on a surface of a semiconductor substrate;

(b) forming a gate electrode on the gate oxide film with the almost all the gate oxide film left;

(c) forming, on the sides of the gate electrode, sidewalls including an oxide film with different etching properties from the gate oxide film and removing exposed portion of the gate oxide film;

(d) implanting ions for forming source and drain regions using the sidewalls as a mask;

(e) etching the sidewalls with a mixed solution containing hydrofluoric acid and an organic solution; and

(f) cleaning the semiconductor substrate with a hydrogen peroxide solution or an ozone solution after the step (e).