Method to increase the compressive stress of PECVD silicon nitride films

• US 20060269692A1
• Filed: 04/05/2006
• Published: 11/30/2006
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Xia, Li-Qun, Balseanu, Mihaela, M'Saad, Hichem, Shek, Mei-Yee, Zubkov, Vladimir, Roflox, Isabelita
• Granted Patent: US 7,732,342 B2
• Time in Patent Office: Days
• US Class Current: 427/569
• CPC Class Codes: C23C 16/0245 by etching with a plasma
• CPC Class Codes: C23C 16/0272 Deposition of sub-layers, e.g. to promote the adhesion of the main coating
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/02301 in-situ cleaning
• CPC Class Codes: H01L 21/02315 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/3185 of siliconnitrides

Abstract

Compressive stress in a film of a semiconductor device may be controlled utilizing one or more techniques, employed alone or in combination. A first set of embodiments increase silicon nitride compressive stress by adding hydrogen to the deposition chemistry, and reduce defects in a device fabricated with a high compressive stress silicon nitride film formed in the presence of hydrogen gas. A silicon nitride film may comprise an initiation layer formed in the absence of a hydrogen gas flow, underlying a high stress nitride layer formed in the presence of a hydrogen gas flow. A silicon nitride film formed in accordance with an embodiment of the present invention may exhibit a compressive stress of 2.8 GPa or higher.

Claims

1. A method of forming silicon nitride, the method comprising:

disposing a substrate including a surface in a processing chamber; and

depositing silicon nitride on the surface by exposing the surface in the processing chamber to a silicon-containing precursor in a hydrogen-containing plasma.

2. The method of claim 1 wherein the hydrogen-containing plasma is formed in a gas mixture including molecular hydrogen.

3. The method of claim 1 wherein the hydrogen-containing plasma comprises at least one precursor selected from a germanium-containing precursor and a carbon-containing precursor.

4. The method of claim 2 wherein the gas mixture further comprises Argon.

5. The method of claim 4 wherein the gas mixture further comprises at least one component selected from molecular nitrogen, Xenon, and Krypton.

6. The method of claim 1 wherein the silicon nitride exhibits a compressive stress of 2.8 GPa or higher.

7. A method of forming silicon nitride, the method comprising:

disposing a substrate including a surface in a processing chamber;

exposing the surface to a plasma in the absence of deposition conditions to remove contamination; and

depositing silicon nitride layer over the plasma-treated surface in the presence of a hydrogen gas flow.

8. The method of claim 7 wherein the plasma is formed from an ambient comprising at least one component selected from ammonia, oxygen, and N₂O.

9. The method of claim 7 wherein the silicon nitride is deposited in the presence of the plasma.

10. The method of claim 7 further comprising forming a buffer layer over the treated surface prior to deposition of the silicon nitride.

11. The method of claim 10 wherein the silicon nitride is deposited as a film stack comprising an initiation layer formed in the absence of the hydrogen gas flow, followed by a high compressive stress layer formed in the presence of the hydrogen gas flow.

12. The method of claim 7 wherein the silicon nitride exhibits a compressive stress of 2.8 GPa or higher.

13. A method of forming silicon nitride, the method comprising:

disposing a substrate including a surface in a processing chamber;

forming a buffer layer over the surface; and

depositing silicon nitride over the buffer layer in the presence of a hydrogen gas flow.

14. The method of claim 13 wherein forming the buffer layer comprises depositing an oxide layer.

15. The method of claim 14 wherein the silicon nitride is deposited as a film stack comprising an initiation layer formed in the absence of the hydrogen gas flow, followed by a high compressive stress layer formed in the presence of the hydrogen gas flow.

16. The method of claim 13 wherein the silicon nitride exhibits a compressive stress of 2.8 GPa or higher.

17. A method of preventing defects in a device, the method comprising:

depositing a silicon nitride initiation layer on a surface in the absence of a flow of hydrogen gas;

depositing a high compressive stress silicon nitride layer on the silicon nitride initiation layer in a presence of a flow of hydrogen gas; and

etching back the high compressive stress silicon nitride layer with a diluted NF₃ plasma.

18. The method of claim 17 wherein the etch back process is performed in the same chamber as the high compressive stress deposition process.

19. The method of claim 17 wherein the etch back process is modulated so that a higher etch rate occurs on isolated areas.

20. The method of claim 17 wherein the high compressive stress silicon nitride layer exhibits a compressive stress of 2.8 GPa or higher.