Method of forming an oxide film on a gate side wall of a gate structure

• US 20030036253A1
• Filed: 10/08/2002
• Published: 02/20/2003
• Est. Priority Date: 04/28/1998
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ko, Shang-Bin, Katata, Tomio, Ajmera, Atul C., Balasubramanyam, Karanam
• Granted Patent: US 6,605,521 B2
• Time in Patent Office: Days
• US Class Current: 438/585
• CPC Class Codes: H01L 21/28061 the conductor comprising a metal or metal silicide formed by deposition, e.g. sputter deposition, i.e. without a silicidation reaction H01L21/28052 takes precedence
• CPC Class Codes: H01L 21/32105 Oxidation of silicon-containing layers
• CPC Class Codes: H01L 29/4933 with a silicide layer contacting the silicon layer, e.g. Polycide gate with a barrier layer between the silicide and silicon layers H01L29/4941

Abstract

In order to prevent abnormal oxidation of the side wall of a polycide gate conductor layer in the oxidation heat treatment process after the RIE processing of the polycide gate conductor layer in a semiconductor memory cell, the heat treatment for oxidizing the side wall of the polycide gate conductor layer is conducted in two steps with different conditions. By conducting the first heat treatment process in an inert atmosphere, a thin oxide film is formed on the side wall of the polycide tungsten/gate conductor layer. Then by conducting the second heat treatment process in an atmosphere with a strong oxidizing property, a thick oxide film without abnormal oxidation can be formed.

Claims

1. A method of forming an oxide film on a gate structure side wall, comprising the steps of:

successively forming an insulating film, a conductor layer, and a metal silicide layer on a semiconductor substrate, forming a gate structure including a gate insulating film, a gate conductor layer, and a gate silicide layer by etching the insulating film, the conductor layer, and the metal silicide layer, and

forming an oxide film on the side wall of the gate structure by forming a thin oxide film on the side wall of the gate structure by the heat treatment of the gate structure with a first heat treatment condition followed by the heat treatment with a second heat treatment condition to thicken the thin oxide film.

2. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the first heat treatment condition includes an inert atmosphere and the second heat treatment condition includes an active atmosphere.

3. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the inert atmosphere in the first heat treatment condition is a nitrogen (N₂) atmosphere, and the active atmosphere in the second heat treatment is an oxygen (O₂) atmosphere.

4. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the inert atmosphere in the first heat treatment condition is an argon (Ar) atmosphere, and the active atmosphere in the second heat treatment is an oxygen (O₂) atmosphere.

5. The method of forming an oxide film an a gate structure side wall according to claim 1, wherein the first heat treatment condition includes a weak oxidizing atmosphere, and the second heat treatment condition includes a strong oxidizing atmosphere.

6. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the heat treatment process of the first heat treatment condition is conducted with a first furnace, and the heat treatment process of the second heat treatment condition is conducted with a second furnace independently from the first furnace.

7. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the heat treatment process of the first heat treatment condition and the heat treatment process of the second heat treatment condition are conducted with a common furnace.

8. The method of forming an oxide film on a gate structure side wall according to claim 1, further comprising a cleaning process between the heat treatment process of the first heat treatment condition and the heat treatment process of the second heat treatment condition.

9. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the conductor layer is a polysilicon layer.

10. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the metal silicide layer is a tungsten silicide layer.

11. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the metal silicide layer is a molybdenum silicide layer.

12. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the heating temperature in the first heat treatment condition is 700 to 1000°

C., and the heating temperature in the second heat treatment condition is 1000 to 1150°

C.

13. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the heating temperature in the first heat treatment condition is 800°

C., and the heating temperature in the second heat treatment condition is 1050°

C.

14. The method of forming an oxide film on a gate structure side wall according to claim 1, wherein the heating time in the first heat treatment condition is 100 to 150 seconds and the heating time in the second heat treatment condition is 20 to 120 seconds.

15. The method of forming an oxide film on a gate structure side wall according to claim 14, wherein the heating time in the first heat treatment condition is 120 seconds and the heating time in the second heat treatment condition is 65 seconds.

16. The method of forming an oxide film on a gate structure side wall according to claim 14, wherein the heating time in the first heat treatment condition is 120 seconds and the heating time in the second heat treatment condition is 100 seconds.

17. The method of forming an oxide film on a gate structure side wall according to claim 14, wherein the heating temperature in the first heat treatment condition is 800°

C., and the heating temperature in the second heat treatment condition is 1100°

C.

18. The method of forming an oxide film on a gate structure side wall according to claim 17, wherein the heating time in the first heat treatment condition is 120 seconds and the heating time in the second heat treatment condition is 40 seconds.