OXIDE ETCH WITH NH4-NF3 CHEMISTRY

• US 20100093151A1
• Filed: 12/18/2009
• Published: 04/15/2010
• Est. Priority Date: 01/11/2007
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kao, Chien-Teh, Arghavani, Reza, Lu, Xinliang
• Granted Patent: US 7,955,510 B2
• Time in Patent Office: Days
• US Class Current: 438/424
• 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 processing a substrate, comprising:

positioning the substrate in a vacuum chamber, wherein a surface of the substrate has a first oxide layer formed thereon;

etching a feature definition in the first oxide layer and the substrate surface;

depositing a second oxide in the feature definition in an amount above the substrate surface;

generating active species of a processing gas mixture comprising a first gas and a second gas at a molar ratio of the first gas to the second gas from 3;

1 to 30;

1;

converting at least a portion of the first oxide and at least a portion of the second oxide to a film on the surface of the substrate; and

sublimating the film formed on the structure to substantially planarize the surface of the substrate.

2. The method of claim 1, wherein depositing the second oxide further comprises depositing a liner oxide in the feature definition and a nitride liner on the liner oxide before depositing the second oxide.

3. The method of claim 1, further comprising cooling the substrate to a first temperature from 15°

C. to 65°

C. prior to generating active species.

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

5. The method of claim 4, wherein the first gas is ammonia (NH₄) and the second gas is nitrogen trifluoride (NF₃).

6. The method of claim 5, wherein the processing gas comprises a molar ratio of ammonia (NH₄) to nitrogen trifluoride (NF₃) at 5:

1.

7. The method of claim 1, wherein the processing gas comprises a molar ratio of the first gas to the second gas from 3:

1 to 10;

1.

8. The method of claim 1, wherein the processing gas mixture further comprises a carrier gas.

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

10. The method of claim 1, wherein the film is a salt comprising nitrogen and fluorine atoms.

11. The method of claim 10, wherein the film comprises ammonium hexafluorosilicate.

12. The method of claim 1, wherein sublimating the film comprises heating the substrate to a second temperature from 75°

C. to 200°

C.

13. The method of claim 12, further comprising removing the sublimated film material from the vacuum chamber.

14. A method for processing a substrate, comprising:

positioning the substrate in a vacuum chamber, wherein the substrate comprises a first oxide layer formed on the surface of the substrate, a feature definition formed in the first oxide layer and the substrate surface, and a second oxide formed in the feature definition in an amount above the substrate surface;

selectively removing the first oxide and the second oxide from the substrate surface by a process comprising;

introducing a processing gas comprising a first gas and a second gas at a molar ratio of the first gas to the second gas from 3;

1 to 30;

1 to the vacuum chamber;

generating a plasma of the processing gas;

exposing the first oxide layer and the second oxide layer to the plasma of the processing gas;

forming a nitrogen and fluorine containing film with at least a portion of the first oxide layer and at least a portion of the second oxide layer; and

sublimating the nitrogen and fluorine containing film from the substrate surface.

15. The method of claim 14, wherein a liner oxide is formed in the feature definition and a nitride liner is formed on the liner oxide before forming the second oxide in the feature definition.

16. The method of claim 15, further comprising forming the nitrogen and fluorine containing film with exposed portions of the liner oxide layer and substantially planarizing the liner oxide with the surface of the substrate.

17. The method of claim 14, wherein the processing gas comprises a molar ratio of ammonia (NH₄) to nitrogen trifluoride (NF₃) from 3:

1 to 10;

1 and the nitrogen and fluorine containing film comprises ammonium hexafluorosilicate.

18. The method of claim 17, wherein the nitrogen and fluorine containing film comprises ammonium hexafluorosilicate.

19. The method of claim 14, wherein the processing gas mixture further comprises a carrier gas.

20. The method of claim 14, wherein sublimating the nitrogen and fluorine containing film from the substrate surface comprises heating the substrate to a second temperature from 75°

C. to 200°

C.