Method of forming a nitride gate dielectric layer for advanced CMOS devices

• US 6,727,134 B1
• Filed: 11/05/2002
• Issued: 04/27/2004
• Est. Priority Date: 11/05/2002
• Status: Expired due to Fees

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Chen, Chi-Chun, Lee, Tze-Liang, Chen, Shih-Chang
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): TRAN, THUY V
• Application Number:
  US10/288,195
• Publication Number:
  US 20040087079A1
• Time in Patent Office: 539 Days
• Field of Search: 438/216, 438/287, 438/197, 438/520, 438/528, 438/585, 438/591
• US Class Current: 438/216
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 21/28211 in a gaseous ambient using an oxygen or a water vapour, e.g. RTO, possibly through a layer H01L21/28194 and H01L21/28202 take precedence
• CPC Class Codes: H01L 21/823857 with a particular manufacturing method of the gate insulating layers, e.g. different gate insulating layer thicknesses, particular gate insulator materials or particular gate insulator implants
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane

Abstract

A process for forming a dielectric stack for use as a gate dielectric layer for sub-0.1 um MOSFET devices has been developed. The process features growth of a thin silicon nitride layer on the surface of a semiconductor substrate via a low temperature plasma nitridization procedure. The conditions used allow a self-limiting silicon nitride layer, in regards to thickness, to be realized. A plasma oxidation procedure is next used to remove bulk traps in the silicon nitride layer in addition to forming a thin silicon oxide layer on the semiconductor surface, underlying the thin silicon nitride layer. The plasma oxidation procedure also results in conversion of a top portion of the silicon layer to silicon oxynitride, thus resulting in a dielectric gate stack comprised of silicon oxynitride-silicon oxide-silicon nitride.

Claims

1. A method of forming a dielectric layer on a semiconductor substrate, comprising the steps of:

performing a first plasma procedure to form a first insulator layer on said semiconductor substrate; and

performing a second plasma procedure to remove traps in said first insulator layer, with said second plasma procedure forming a second insulator layer on said semiconductor substrate underlying said first insulator layer, and converting a top portion of said first insulator layer to a third insulator layer, resulting in said dielectric layer comprised of said third insulator layer on a bottom portion of said first insulator layer, and an underlying second insulator layer.

2. The method of claim 1, wherein said first plasma procedure is a remote plasma nitridization procedure.

3. The method of claim 1, wherein said first plasma procedure is performed at a temperature between about 25 to 700°

C.

4. The method of claim 1, wherein said first plasma procedure is performed at a power between about 100 to 300 watts, and at a pressure between about 1 mtorr to 10 torr.

5. The method of claim 1, wherein said first plasma procedure is performed for a time of 5 sec, or greater.

6. The method of claim 1, wherein said first plasma procedure is performed in a nitrogen ambient.

7. The method of claim 1, wherein said first insulator layer is a silicon nitride layer, formed at a thickness between about 5 to 30 Angstroms, via said first plasma procedure, formed independent of plasma time.

8. The method of claim 1, wherein a refractive index of said first insulator layer is between about 1.95 to 2.05.

9. The method of claim 1, wherein said second plasma procedure is a remote plasma oxidation procedure, performed in an oxygen ambient, in situ in same chamber used to perform said first plasma procedure.

10. The method of claim 1, wherein said second plasma procedure is performed at a temperature between about 200 to 700°

C.

11. The method of claim 1, wherein said second plasma procedure is performed at a power between about 100 to 3000 watts, and at a pressure between about 1 mtorr to 10 torr.

12. The method of claim 1, wherein said second plasma procedure is performed for a time between about 5 to 60 sec.

13. The method of claim 1, wherein said second insulator layer is a silicon oxide layer, formed at a thickness between about 5 to 30 Angstroms.

14. The method of claim 1, wherein said third insulator layer is a silicon oxynitride layer, formed at a thickness between about 6 to 30 Angstroms.

15. The method of claim 1, wherein said dielectric layer comprised of said third insulator layer, of bottom portion of said first insulator layer, and of said second insulator layer is comprised with an equivalent oxide thickness (EOT), between about 5 to 20 Angstroms.

16. A method of forming a nitride-oxide composite stack layer for use as a gate dielectric layer, on a semiconductor substrate, comprising the steps of:

performing a wet clean procedure to remove native oxide from surface of said semiconductor substrate;

performing a plasma nitridization procedure in a plasma tool to form a silicon nitride layer on said semiconductor substrate; and

performing a plasma oxidation procedure, in situ in said plasma tool, removing bulk traps in said silicon nitride layer while forming a silicon oxide layer on said semiconductor substrate located underlying said silicon nitride layer, and converting a top portion of said silicon nitride layer to a silicon oxynitride layer, resulting in said nitride-oxide stack layer comprised of said silicon oxynitride layer, of a bottom portion of said silicon nitride layer, and of an underlying silicon oxide layer.

17. The method of claim 16, wherein said plasma nitridization procedure is performed at a temperature between about 25 to 700°

C.

18. The method of claim 16, wherein said plasma nitridization procedure is performed at a power between about 100 to 300 watts, and at a pressure between about 1 mtorr to 10 torr.

19. The method of claim 16, wherein said plasma nitridization procedure is performed for a time of 5 sec, or greater.

20. The method of claim 16, wherein said plasma nitridization procedure is performed in a nitrogen ambient.

21.The method of claim 16, wherein said silicon nitride layer is formed at a thickness between about 5 to 30 Angstroms, via said plasma nitridization procedure, with the thickness of said silicon nitride layer obtained independent of plasma time.

21. The method of claim 16, wherein a refractive index of said silicon nitride layer is between about 1.95 to 2.05.

22. The method of claim 16, wherein said plasma oxidation procedure is performed at a temperature between about 200 to 700°

C., in an oxygen ambient.

23. The method of claim 16, wherein said plasma oxidation procedure is performed at a power between about 100 to 3000 watts, and at a pressure between about 1 mtorr to 10 torr.

24. The method of claim 16, wherein said plasma oxidation procedure is performed for a time between about 5 to 60 sec.

25. The method of claim 16, wherein said silicon oxide layer is formed at a thickness between about 5 to 30 Angstroms.

26. The method of claim 16, wherein said silicon oxynitride layer is formed at a thickness between about 6 to 30 Angstroms.

27. The method of claim 16, wherein said nitride-oxide composite stack layer is comprised with an equivalent oxide thickness (EOT), between about 5 to 20 Angstroms.