Silicon nitride etching in a single wafer apparatus

Patent metadata

Field	Value
Publication number	US-9355874-B2
Application number	US-201113244337-A
Country	US
Kind code	B2
Filing date	Sep 24, 2011
Priority date	Sep 24, 2011
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

A single wafer etching apparatus and various methods implemented in the single wafer etching apparatus are disclosed. In an example, etching a silicon nitride layer in a single wafer etching apparatus includes: heating a phosphoric acid to a first temperature; heating a sulfuric acid to a second temperature; mixing the heated phosphoric acid and the heated sulfuric acid; heating the phosphoric acid/sulfuric acid mixture to a third temperature; and etching the silicon nitride layer with the heated phosphoric acid/sulfuric acid mixture.

First claim

What is claimed is:

1. A method comprising:
etching a silicon nitride layer in a single wafer etching apparatus, wherein the etching the silicon nitride layer includes:
heating a phosphoric acid to a first temperature;
heating a sulfuric acid to a second temperature;
mixing the heated phosphoric acid and the heated sulfuric acid in a volume ratio of phosphoric acid to sulfuric acid equal to about 1:9;
heating the phosphoric acid/sulfuric acid mixture to an etching temperature; and
etching the silicon nitride layer with the heated phosphoric acid/sulfuric acid mixture;
wherein mixing the heated phosphoric acid and the heated sulfuric acid occurs simultaneously with heating the phosphoric acid/sulfuric acid mixture to the etching temperature.

2. The method of claim 1 further comprising mixing a heated water vapor with the phosphoric acid/sulfuric acid mixture.

3. The method of claim 1 wherein mixing the heated phosphoric acid and the heated sulfuric acid includes using an exothermic reaction between the sulfuric acid and water vapor or hot water.

4. The method of claim 1 wherein the etching the silicon nitride layer with the heated phosphoric acid/sulfuric acid mixture includes dispensing the heated phosphoric acid/sulfuric acid mixture onto a spinning wafer surface, wherein the wafer includes the silicon nitride layer.

5. The method of claim 1 wherein the phosphoric acid/sulfuric acid mixture contains a larger proportion of sulfuric acid relative to phosphoric acid, by volume.

6. A method comprising:
etching a material layer in a single wafer etching apparatus, wherein the etching the material layer includes:
mixing phosphoric acid and sulfuric acid in a volume ratio of phosphoric acid to sulfuric acid equal to about 1:9;
heating the phosphoric acid/sulfuric acid mixture to an etching temperature, wherein the heating includes injecting water vapor into the phosphoric acid/sulfuric acid mixture, and wherein mixing the phosphoric acid and the sulfuric acid occurs simultaneously with heating the phosphoric acid/sulfuric acid mixture to the etching temperature; and
etching the material layer with the heated phosphoric acid/sulfuric acid mixture.

7. The method of claim 6 further comprising, before mixing the phosphoric acid and the sulfuric acid:
heating the phosphoric acid to a first temperature; and
heating the sulfuric acid to a second temperature.

8. The method of claim 6 wherein the heating the phosphoric acid/sulfuric acid mixture to the etching temperature includes using an exothermic reaction between the sulfuric acid and the water vapor or hot water.

9. The method of claim 6 wherein etching the material layer with the heated phosphoric acid/sulfuric acid mixture includes etching a material layer that includes silicon-containing portions and silicon nitride portions, wherein the heated phosphoric acid/sulfuric acid mixture selectively etches the silicon nitride portions.

10. The method of claim 9 wherein the silicon-containing portions are silicon oxide portions of the material layer.

11. The method of claim 1 wherein the etching temperature is greater than or equal to about 120° C.

12. The method of claim 6 wherein the etching temperature is greater than or equal to about 120° C.

13. The method of claim 1 wherein the phosphoric acid/sulfuric acid mixture has a lower viscosity than the phosphoric acid.

14. The method of claim 13 wherein the lower viscosity of the phosphoric acid/sulfuric acid mixture results in at least one of improved etch selectivity, improved etch uniformity, and improved defectivity performance.

15. The method of claim 6 wherein the phosphoric acid/sulfuric acid mixture has a lower viscosity than the phosphoric acid.

16. The method of claim 15 wherein the lower viscosity of the phosphoric acid/sulfuric acid mixture results in at least one of improved etch selectivity, improved etch uniformity, and improved defectivity performance.

Assignees

• Yu Weibo
• Lu Hsueh-Chin
• Chew Han-Guan
• Huang Kuo Bin
• Chen Chao-Cheng
• Jang Syun-Ming
• Taiwan Semiconductor Mfg

Inventors

• Yu Weibo
• Lu Hsueh-Chin
• Chew Han-Guan
• Huang Kuo Bin
• Chen Chao-Cheng
• Jang Syun-Ming

Classifications

• H10P50/283

  by chemical means · CPC title

• H10P72/0424 Primary

  using mainly spraying means, e.g. nozzles · CPC title

• H01L21/6708 Primary

  Electricity · mapped topic

• H01L21/31111

  Electricity · mapped topic