OXIDE ETCH WITH NH4-NF3 CHEMISTRY

• US 20070123051A1
• Filed: 01/11/2007
• Published: 05/31/2007
• Est. Priority Date: 02/26/2004
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Arghavani, Reza, Kao, Chien-Teh, Lu, Xinliang
• Application Number:
  US11/622,437
• Publication Number:
  US 20070123051A1
• Time in Patent Office: Days
• US Class Current: 438/715
• CPC Class Codes: H01L 21/02057 Cleaning during device manufacture
• CPC Class Codes: H01L 21/02068 during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
• CPC Class Codes: H01L 21/31055 the removal being a chemical etching step, e.g. dry etching etching per se H01L21/311
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
• CPC Class Codes: H01L 29/665 using self aligned silicidation, i.e. salicide formation of conductive layers comprising silicides H01L21/28518
• CPC Class Codes: H01L 29/6656 using multiple spacer layers, e.g. multiple sidewall spacers
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence

Abstract

The present invention generally provides apparatus and methods for selectively removing various oxides on a semiconductor substrate. One embodiment of the invention provides a method for selectively removing an oxide on a substrate at a desired removal rate using an etching gas mixture. The etching gas mixture comprises a first gas and a second gas, and a ratio of the first gas and a second gas is determined by the desired removal rate.

Claims

1. A method for selectively removing an oxide on a substrate at a desired removal rate, comprising:

positioning the substrate in a vacuum chamber, wherein a surface of the substrate has a structure comprises the oxide;

cooling the substrate to a first temperature;

generating active species of an etching gas mixture within the vacuum chamber, wherein the etching gas mixture comprises a first gas and a second gas, and a ratio of the first gas and a second gas is determined by the desired removal rate;

exposing the structure on the surface of the substrate to the active species to form a film on the structure;

heating the substrate to vaporize the film formed on the structure; and

removing the vaporized film from the vacuum chamber.

2. The method of claim 1, wherein the active species comprise nitrogen and fluorine atoms.

3. The method of claim 1, wherein the structure comprises another oxide.

4. The method of claim 3, wherein the etching gas mixture removes the another oxide at a second removal rate.

5. The method of claim 4, wherein the second removal rate is substantially equal to the desired removal rate.

6. The method of claim 1, wherein the first gas is ammonia (NH₄) and the second gas is nitrogen trifluoride (NF₃).

7. The method of claim 6, wherein the ratio of ammonia and nitrogen trifluoride is about at least 3:

1.

8. The method of claim 6, wherein the ratio of ammonia and nitrogen trifluoride is between about 10:

1 to about 20;

1.

9. The method of claim 1, wherein the etching gas mixture further comprises a carrier gas.

10. The method of claim 1, further comprising introducing a carrier gas to the vacuum chamber prior to generating the active species.

11. A method for processing a substrate having an oxide structure comprising a first oxide and a second oxide, comprising:

positioning the substrate in a vacuum chamber;

cooling the substrate to a first temperature;

introducing an etching gas mixture into the vacuum chamber, wherein the etching gas mixture is adjusted to reduce the first oxide at a first rate and the second oxide at a second rate;

generating a plasma of the etching gas mixture within the vacuum chamber;

exposing the oxide structure to the plasma to form a film on the structure;

heating the substrate to vaporize the film formed on the oxide structure; and

removing the vaporized film from the vacuum chamber.

12. The method of claim 11, wherein the first oxide a thermal grown oxide and the second oxide is a deposited oxide.

13. The method of claim 11, wherein the oxide structure further comprises a native oxide.

14. The method of claim 11, wherein the first rate is substantially equal to the second rate.

15. The method of claim 11, the etching gas mixture comprises ammonia (NH₄) and nitrogen trifluoride (NF₃).

16. The method of claim 15, wherein a molar ratio of ammonia and nitrogen trifluoride is about at least 3:

1.

17. A method for processing a substrate, comprising:

positioning the substrate in a vacuum chamber, wherein the substrate having a surface feature comprising a first oxide and a second oxide;

introducing an etching gas mixture to the vacuum chamber;

generating active species from the etching gas mixture;

at least partially reducing the first oxide by exposing the surface feature to the plasma of the etching gas mixture; and

reducing the second oxide by an aqueous etch process.

18. The method of claim 17, wherein the etching gas mixture comprises comprises ammonia (NH₄) and nitrogen trifluoride (NF₃).

19. The method of claim 18, further comprising adjusting a molar ratio of ammonia and nitrogen trifluoride to selectively remove the first oxide.

20. The method of claim 17, wherein reducing the second oxide comprises providing a diluted hydrofluoric acid solution.