Method for fabricating shallow trench isolation

• US 20020055236A1
• Filed: 01/25/2001
• Published: 05/09/2002
• Est. Priority Date: 11/08/2000
• Status: Active Grant

• Current Assignee: Macronix International Co., Ltd.
• Original Assignee: Macronix International Co., Ltd.
• Inventors: Chen, Wei-Wen
• Granted Patent: US 6,541,350 B2
• Time in Patent Office: Days
• US Class Current: 438/437
• CPC Class Codes: H01L 21/76237 introducing impurities in trench side or bottom walls, e.g. for forming channel stoppers or alter isolation behavior

Abstract

A method for forming shallow trench isolation is disclosed. A pad oxide layer and a mask layer are sequentially formed on a substrate. Afterwards, an opening is formed through the mask layer and the pad oxide layer such that regions of the substrate are exposed. Thereafter, the exposed regions are etched to form trenches inside said substrate. Next, nitrogen ions are implanted into the sidewall of the trenches to form a silicon nitride layer, and then a siliconoxynitride layer is formed inside the sidewall of the trenches. Subsequently, a silicon oxide layer is formed on the siliconoxynitride layer and on the mask layer. The excess portion of the silicon oxide layer over said mask layer is removed to expose the mask layer, and then the mask layer is removed away. Finally, the pad oxide layer is removed by using hydrofluoric acid (HF).

Claims

1. A method for forming shallow trench isolation, comprising the steps of:

forming a pad oxide layer on a substrate;

forming a mask layer on said pad oxide layer;

forming an opening through said mask layer and said pad oxide layer such that regions of said substrate are exposed;

etching said exposed regions to form trenches inside said substrate;

implanting nitrogen ions into the sidewall of said trenches to form a silicon nitride layer;

forming a siliconoxynitride layer on said sidewall of said trenches;

forming a silicon oxide layer on said siliconoxynitride layer and said mask layer;

removing the excess portion of said silicon oxide layer over said mask layer to expose said mask layer;

removing said mask layer; and

removing said pad oxide layer by using hydrofluoric acid (HF).

2. The method of claim 1, wherein said implanting step uses an energy between about 1 keV and 10 keV.

3. The method of claim 1, wherein said implanting step uses a dosage between about 1 E15/cm³ and 1 E17/cm³.

4. The method of claim 1, wherein said implanting step uses tilt angles between about 7°

and 30°

.

5. The method of claim 1, wherein the twist angle of said implanting step is 90°

.

6. The method of claim 1, wherein the thickness of said silicon oxide layer is between about 25 angstroms and 200 angstroms.

7. The method of claim 1, wherein the thickness of said siliconoxynitride layer is between about 25 angstroms and 200 angstroms.

8. The method of claim 1, wherein the step of forming said siliconoxynitride layer comprises using a thermal oxidation process.

9. The method of claim 8, wherein the temperature of said thermal oxidation process is between about 650°

C. and 900°

C.

10. The method of claim 1, wherein the step of forming said silicon oxide layer comprises a high-density plasma chemical vapor deposition (HDPCVD) process.

11. The method of claim 1, wherein the step of removing the excess portion of said silicon oxide layer comprises etch back and chemical mechanical polishing process.

14. The method of claim 13, wherein said implanting step uses an energy between about 1 keV and 10 keV.

15. The method of claim 13, wherein said implanting step uses a dosage between about 1 E15/cm³ and 1 E17/cm³.

16. The method of claim 13, wherein said implanting step uses tilt angles between about 7°

and 30°

.

17. The method of claim 13, wherein the twist angle of said implanting step is 90°

18. The method of claim 13, wherein the thickness of said silicon oxide layer is between about 25 angstroms and 200 angstroms.

19. The method of claim 13, wherein the thickness of said siliconoxynitride layer is between about 25 angstroms and 200 angstroms.

20. The method of claim 13, wherein the step of removing the excess portion of said silicon oxide layer comprises etch back and chemical mechanical polishing process.

12. A method for forming shallow trench isolation, comprising the steps of:

forming sequentially a mask layer and a pad oxide layer on a substrate;

forming a opening through said mask layer and said pad oxide layer to expose a portion of said substrate;

etching said exposed substrate for forming trenches inside said substrate;

implanting nitrogen ions into the sidewall of said trenches to form a silicon nitride layer wherein the implant energy of said implanting nitrogen ions is between about 1 keV and 10 keV;

forming a siliconoxynitride layer on said sidewall of said trenches by using a thermal oxidation process wherein the temperature of said thermal oxidation process is between about 650°

C. and 900°

C.;

forming a silicon oxide layer on said siliconoxynitride layer and said mask layer by using a high-density plasma chemical vapor deposition process;

removing the excess portion of said silicon oxide layer over said mask layer to expose said mask layer; and

removing said mask layer.

13. A method for forming shallow trench isolation, comprising the steps of:

forming a pad oxide layer on a substrate;

forming a mask layer on said pad oxide layer;

forming an opening through said mask layer and said pad oxide layer such that regions of said substrate are exposed;

etching said exposed regions for forming trenches inside said substrate;

implanting nitrogen ions into the sidewall of said trenches to form a silicon nitride layer;

forming a siliconoxynitride layer on said sidewall of said trenches by using a thermal oxidation process wherein the temperature of said thermal oxidation process is between about 650°

C. and 900°

C.;

forming a silicon oxide layer on said siliconoxynitride layer and said mask layer by using a high-density plasma chemical vapor deposition process;

removing the excess portion of said silicon oxide layer over said mask layer to expose said mask layer,

removing said mask layer; and

removing said pad oxide layer by using hydrofluoric acid (HF).