Process for fabricating semiconductor device and method of fabricating metal oxide semiconductor device

• US 8,741,784 B2
• Filed: 09/20/2011
• Issued: 06/03/2014
• Est. Priority Date: 09/20/2011
• Status: Active Grant

• Current Assignee: United Microelectronics Corporation
• Original Assignee: United Microelectronics Corporation
• Inventors: Lin, Chien-Liang, Sun, Te-Lin, Yen, Ying-Wei, Wang, Yu-Ren
• Primary Examiner(s): AU, BAC H
• Application Number:
  US13/237,232
• Publication Number:
  US 20130072028A1
• Time in Patent Office: 987 Days
• Field of Search: 438/591, 438/770, 438/778, 438/787, 438/775, 438/776
• US Class Current: 438/776
• CPC Class Codes: H01L 21/0214 the material being a silicon oxynitride, e.g. SiON or SiON:H
• CPC Class Codes: H01L 21/02332 into an oxide layer, e.g. changing SiO to SiON
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/28185 with a treatment, e.g. annealing, after the formation of the gate insulator and before the formation of the definitive gate conductor
• 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 21/823857 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 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material

Abstract

A process for fabricating a semiconductor device is described. A silicon oxide layer is formed. A nitridation process including at least two steps is performed to nitridate the silicon oxide layer into a silicon oxynitride (SiON) layer. The nitridation process comprises a first nitridation step and a second nitridation step in sequence, wherein the first nitridation step and the second nitridation step are different in the setting of at least one parameter.

Claims

1. A process for fabricating a semiconductor device, comprising:

forming a silicon oxide layer, wherein forming the silicon oxide layer comprises an in-situ steam generation (ISSG) oxidation process or a decoupled plasma oxidation process; and

performing a nitridation process including at least two steps to nitridate the silicon oxide layer into a silicon oxynitride (SiON) layer, wherein the nitridation process comprises a first nitridation step and a second nitridation step, and the first nitridation step and the second nitridation step are different in setting of at least one parameter,

wherein the first nitridation step and the second nitridation step each comprises remote plasma nitridation, or NH₃ thermal nitridation;

the electric power of the first nitridation step is higher than the electric power of the second nitridation step, so that a peak of the resulting nitrogen concentration profile from the first nitridation step is farther away from a top surface of the silicon oxide layer, and nitrogen atoms provided by the second nitridation step are closer to the top surface of the silicon oxide layer; and

a time period of the second nitridation step is longer than a time period of the first nitridation step, so that nitrogen penetration through the silicon oxide layer is prevented or reduced during the first nitridation step.

2. The process of claim 1, wherein the first nitridation step is performed before the second nitridation step.

3. The process of claim 1, wherein a duty cycle of the first nitridation step is larger than a duty cycle of the second nitridation step.

4. The process of claim 1, wherein the first nitridation step is performed after the second nitridation step.

5. The process of claim 1, further comprising a post-annealing process.

6. The process of claim 5, wherein the post-annealing process comprises a nitrogen gas annealing step and an oxygen gas annealing step in sequence.

7. A method of fabricating a MOS device, comprising:

forming a silicon oxide layer, wherein forming the silicon oxide layer comprises an in-situ steam generation (ISSG) oxidation process or a decoupled plasma oxidation process;

performing a nitridation process including at least two steps to nitridate the silicon oxide layer into a SiON layer, wherein the nitridation process comprises a first nitridation step and a second nitridation step, and the first nitridation step and the second nitridation step are different in setting of at least one parameter,

wherein the first nitridation step and the second nitridation step each comprises remote plasma nitridation, or NH₃ thermal nitridation;

the electric power of the first nitridation step is higher than the electric power of the second nitridation step, so that a peak of the resulting nitrogen concentration profile from the first nitridation step is farther away from a top surface of the silicon oxide layer, and nitrogen atoms provided by the second nitridation step are closer to the top surface of the silicon oxide layer,

a time period of the second nitridation step is longer than a time period of the first nitridation step, so that nitrogen penetration through the silicon oxide layer is prevented or reduced during the first nitridation step; and

forming a conductive layer on the SiON layer.

8. The method of claim 7, wherein the first nitridation step is performed before the second nitridation step.

9. The method of claim 7, wherein a duty cycle of the first nitridation step is larger than a duty cycle of the second nitridation step.

10. The method of claim 7, wherein the first nitridation step is performed after the second nitridation step.

11. The method of claim 7, further comprising a post-annealing process.

12. The method of claim 11, wherein the post-annealing process comprises a nitrogen gas annealing step and an oxygen gas annealing step in sequence.