Process for forming thin dielectric layers in semiconductor devices

• US 6,281,141 B1
• Filed: 02/08/1999
• Issued: 08/28/2001
• Est. Priority Date: 02/08/1999
• Status: Expired due to Term

• Current Assignee: Mattson Technology, Inc. (Beijing Economic & Technology Development Area), BeiJing E-Town Semiconductor Technology Co., Ltd.
• Original Assignee: STEAG RTP Systems, Inc. (KSBG Kommunale Beteiligungsgesellschaft GmbH & Company KG)
• Inventors: Thakur, Randhir P. S., Das, John H.
• Primary Examiner(s): POMPEY, RON EVERETT
• Application Number:
  US09/246,821
• Time in Patent Office: 932 Days
• Field of Search: 438/770, 438/771
• US Class Current: 438/770
• CPC Class Codes: H01L 21/0214 the material being a silicon oxynitride, e.g. SiON or SiON:H
• CPC Class Codes: H01L 21/02238 silicon in uncombined form, i.e. pure silicon
• CPC Class Codes: H01L 21/02255 formation by thermal treatment H01L21/02252 takes precedence; after treatment of an insulating film H01L21/3105 and subgroups
• 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 21/28202 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 21/3144 on silicon
• CPC Class Codes: H01L 21/31662 of silicon in uncombined form
• CPC Class Codes: H01L 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material

Abstract

A process for producing thin dielectric films is disclosed. In particular, the process is directed to forming oxide films having a thickness of less than about 60 angstroms. The oxide films can be doped with an element, such as nitrogen or boron. For example, in one embodiment, an oxynitride coating can be formed on a semiconductor wafer. According to the present invention, the very thin coatings are formed by reacting a gas with a semiconductor wafer while the temperature of the wafer is being increased in a rapid thermal processing chamber to a maximum temperature. According to the process, primarily all of the coating is formed during the “ramp up” portion of the heating cycle. Consequently, the wafer is maintained at the maximum target temperature for a very short period of time.

Claims

1. A process for forming thin oxide coatings on a semiconductor device, said process comprising the steps of:

placing a semiconductor wafer in a thermal processing chamber;

heating said semiconductor wafer in said chamber, said wafer being increased in temperature to a first target temperature at a first preselected rate;

circulating a first gas within said chamber, said first gas containing an oxygen compound;

reacting said first gas with said semiconductor wafer to form an oxide coating while the temperature of said semiconductor wafer is being increased at said first preselected rate to said first target temperature, wherein said wafer is maintained at said first target temperature for less than about 2 seconds, said oxide coating having a thickness of up to about 60 angstroms;

cooling said semiconductor wafer;

reheating said semiconductor wafer in said chamber, said wafer being increased in temperature to a second target temperature at a second preselected rate;

circulating a second gas within said chamber, said second gas containing a nitrogen compound; and

reacting said second gas with said oxide coating to form an oxynitride while the temperature of said semiconductor wafer is being increased at said second preselected rate to said second target temperature, wherein said wafer is maintained at said second target temperature for less than about 2 seconds.

2. A process as defined in claim 1, wherein said first gas comprises a material selected from the group consisting of molecular oxygen, steam, and mixtures thereof.

3. A process as defined in claim 1, wherein said second gas comprises a material selected from the group consisting of dinitrogen oxide, nitrogen oxide, ammonia, molecular nitrogen and mixtures thereof.

4. A process as defined in claim 1, wherein said first preselected rate and said second preselected rate are average rates of from about 50°

C. per second to about 250°

C. per second.

5. A process as defined in claim 1, wherein said first target temperature and said second target temperature range from about 700°

C. to about 1,200°

C.

6. A process as defined in claim 1, wherein said oxide coating has a thickness of from about 10 angstroms to about 50 angstroms.

7. A process as defined in claim 1, further comprising the steps of:

subsequently cooling said semiconductor wafer after forming said oxynitride; and

reoxidizing said semiconductor wafer by reacting said wafer with oxygen.

8. A process as defined in claim 7, wherein said reoxidation process comprises the steps of:

reheating said semiconductor wafer in said chamber, said wafer being increased in temperature to a third target temperature at a third preselected rate;

circulating a compound containing oxygen within said chamber; and

reacting said compound containing oxygen with said semiconductor wafer while the temperature of said semiconductor wafer is being increased at said third preselected rate to said third target temperature, wherein said wafer is maintained at said third target temperature for less than about 2 seconds.

9. A process as defined in claim 1, wherein said semiconductor wafer is heated to a temperature of less than about 600°

C. prior to reheating said wafer and reacting said wafer with said second gas.

10. A process as defined in claim 1, wherein said semiconductor wafer is heated using light energy.

11. A process for forming thin oxide coatings on a semiconductor device, said process comprising the steps of:

placing a semiconductor wafer in a thermal processing chamber;

heating said semiconductor wafer in said chamber using light energy, said wafer being increased in temperature to a first target temperature at a first preselected rate, said preselected rate being an average rate ranging from about 50°

C. per second to about 250°

C. per second;

circulating a first gas within said chamber, said first gas containing an oxygen compound;

reacting said first gas with said semiconductor wafer to form an oxide coating while the temperature of said semiconductor wafer is being increased at said first preselected rate to said first target temperature, wherein said wafer is maintained at said first target temperature for less than about 1 second, said oxide coating having a thickness of up to about 100 angstroms;

cooling said semiconductor wafer;

reheating said semiconductor wafer in said chamber, said wafer being increased in temperature to a second target temperature at a second preselected rate, said second preselected rate being an average rate ranging from about 50°

C. per second to about 250°

C. per second;

circulating a second gas within said chamber, said second gas containing a nitrogen compound; and

reacting said second gas with said oxide coating to form an oxynitride while the temperature of said semiconductor wafer is being increased at said second preselected rate to said second target temperature, wherein said wafer is maintained at said second target temperature for less than about 1 second.

12. A process for forming thin oxide coatings on a semiconductor device, said process comprising the steps of:

placing a semiconductor wafer in a thermal processing chamber;

heating said semiconductor wafer in said chamber, said wafer being increased in temperature to a target temperature at a preselected rate;

circulating a reactive gas within said chamber; and

reacting said gas with said semiconductor wafer to form an oxide coating while the temperature of said semiconductor wafer is being increased at said preselected rate to said target temperature, wherein said wafer is maintained at said target temperature for less than about 1 second.

13. A process for forming thin oxide coatings on a semiconductor device, said process comprising the steps of:

placing a semiconductor wafer in a thermal processing chamber;

heating said semiconductor wafer in said chamber, said wafer being increased in temperature to a target temperature at a preselected rate;

circulating a reactive gas within said chamber, wherein said reactive gas comprises a material selected from the group consisting of molecular oxygen, ozone, steam and mixtures thereof;

reacting said gas with said semiconductor wafer to form an oxide coating while the temperature of said semiconductor wafer is being increased at said preselected rate to said target temperature, wherein said wafer is maintained at said target temperature for less than about 2 seconds;

cooling said semiconductor wafer after forming said oxide coating;

reheating said semiconductor wafer in said chamber, said wafer being increased in temperature to a second target temperature at a second preselected rate;

circulating a gas comprising a compound containing nitrogen within said chamber; and

reacting said oxide coating with nitrogen contained in said gas to form an oxynitride while the temperature of said semiconductor wafer is being increased at said second preselected rate to said second target temperature, wherein said wafer is maintained at said second target temperature for less than about 2 seconds.

14. A process as defined in claim 13, wherein said compound containing nitrogen comprises a material selected from the group consisting of dinitrogen oxide, nitrogen oxide, nitric oxide, ammonia, molecular nitrogen, and mixtures thereof.

15. A process as defined in claim 13, further comprising the steps of:

subsequently cooling said semiconductor wafer after forming said oxynitride; and

reoxidizing said semiconductor wafer by reacting said wafer with oxygen, ozone or mixtures thereof.

16. A process as defined in claim 15, wherein said reoxidation process comprises the steps of:

reheating said semiconductor wafer in said chamber, said wafer being increased in temperature to a third target temperature at a third preselected rate;

circulating a compound containing oxygen within said chamber; and

reacting said compound containing oxygen with said semiconductor wafer while the temperature of said semiconductor wafer is being increased at said third preselected rate to said third target temperature, wherein said wafer is maintained at said third target temperature for less than about 2 seconds.