Ultra-thin resist and oxide/nitride hard mask for metal etch

• US 6,171,763 B1
• Filed: 12/02/1998
• Issued: 01/09/2001
• Est. Priority Date: 12/02/1998
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Wang, Fei, Levinson, Harry J., Bell, Scott A., Yang, Chih Yuh, Lyons, Christopher F., Nguyen, Khanh B.
• Primary Examiner(s): Huff, Mark F.
• Assistant Examiner(s): BARRECA, NICOLE M
• Application Number:
  US09/204,651
• Time in Patent Office: 769 Days
• Field of Search: 430/313, 430/318, 216/41
• US Class Current: 430/318
• CPC Class Codes: G03F 7/094 Multilayer resist systems, e.g. planarising layers
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: G03F 7/405 Treatment with inorganic or organometallic reagents after imagewise removal
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/32139 using masks

Abstract

In one embodiment, the present invention relates to a method of forming a metal line, involving the steps of providing a semiconductor substrate comprising a metal layer, a silicon nitride layer over the metal layer, and an oxide layer over the silicon nitride layer; depositing an ultra-thin photoresist over the oxide layer, the ultra-thin photoresist having a thickness less than about 2,000 Å; irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 250 nm or less; developing the ultra-thin photoresist exposing a portion of the oxide layer; etching the exposed portion of the oxide layer exposing a portion of the silicon nitride layer; etching the exposed portion of the silicon nitride layer exposing a portion of the metal layer; and etching the exposed portion of the metal layer thereby forming the metal line.

Claims

1. A method of forming a metal line, comprising:

providing a semiconductor substrate comprising a metal layer, a silicon nitride layer over the metal layer, and an oxide layer over the silicon nitride layer;

depositing an ultra-thin photoresist over the oxide layer, the ultra-thin photoresist having a thickness less than about 2,000 Å

;

irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 250 nm or less;

developing the ultra-thin photoresist exposing a portion of the oxide layer;

etching the exposed portion of the an oxide layer exposing a portion of the silicon nitride layer with a first etch chemistry being oxide;

photoresist selective;

etching the exposed portion of the silicon nitride layer exposing a portion of the metal layer with a second etch chemistry being both silicon nitride;

oxide selective and silicon nitride;

metal selective; and

etching the exposed portion of the metal layer with a third etch chemistry being metal;

silicon nitride selective thereby forming the metal line.

2. The method of claim 1, wherein the metal layer comprises a metal selected from the group consisting of aluminum, copper, aluminum-copper alloys, aluminum alloys, and copper alloys.

3. The method of claim 1, wherein the an oxide layer comprises a material selected from the group consisting of silicon dioxide, fluorine doped silicon glass, tetraethylorthosilicate, phosphosilicate glass, and borephospholilicate glass.

4. The method of claim 1, wherein the metal layer has a thickness from about 1,000 Å

to about 20,000 Å

, the silicon nitride layer has a thickness from about 500 Å

to about 5,000 Å

, and the oxide layer has a thickness from about 1,000 Å

to about 10,000 Å

.

5. The method of claim 1, wherein the electromagnetic radiation has a wavelength of about 13 nm or about 11 nm.

6. The method of claim 1, wherein the silicon nitride layer comprises Si₃N₄.

7. The method of claim 1, wherein the metal line has a width of about 0.1 μ

m or less.

8. The method of claim 1, wherein the second etch chemistry comprises fluorine.

9. The method of claim 8, wherein the third etch chemistry comprises chlorine.

10. A method of etching metal to form metal lines, comprising:

providing a semiconductor substrate comprising a metal layer, a silicon nitride layer over the metal layer, and an oxide layer over the silicon nitride layer;

depositing an ultra-thin photoresist over the oxide layer, the ultra-thin photoresist having a thickness from about 500 Å

to about 2,000 Å

;

irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 200 nm or less;

developing the ultra-thin photoresist exposing a portion of the oxide layer, wherein the exposed portion of the oxide layer has a width of about 0.1 μ

m or less;

etching the exposed portion of the oxide layer exposing a portion of the silicon nitride layer with a first etch chemistry being oxide;

photoresist selective;

etching the exposed portion of the silicon nitride layer exposing a portion of the metal layer with a second etch chemistry being both silicon nitride;

oxide selective and silicon nitride;

metal selective; and

etching the exposed portion of the metal layer with a third etch chemistry being metal;

silicon nitride selective thereby forming metal lines.

11. The method of claim 10, wherein the ultra-thin photoresist has a thickness from about 600 Å

to about 1,750 Å

.

12. The method of claim 10, wherein the an oxide layer comprises a material selected from the group consisting of silicon dioxide, fluorine doped silicon glass, tetraethylorthosilicate, phosphosilicate glass, and borephospholilicate glass.

13. The method of claim 10, wherein the electromagnetic radiation has a wavelength of about 13 nm or about 11 nm.

14. The method of claim 10, wherein the metal layer has a thickness from about 2,500 Å

to about 15,000 Å

, the silicon nitride layer has a thickness from about 1,000 Å

to about 4,000 Å

, and the oxide layer has a thickness from about 1,500 Å

to about 9,000 Å

.

15. The method of claim 10, wherein the first etch chemistry being oxide:

photoresist selective comprises etch selectivity of at least about 3;

1.

16. The method of claim 10, wherein the second etch chemistry being silicon nitride:

oxide selective comprises etch selectivity of at least about 3;

1.

17. The method of claim 10, wherein the second etch chemistry comprises fluorine.

18. The method of claim 17, wherein the third etch chemistry comprises chlorine.

19. A method of processing a semiconductor substrate, comprising:

providing a semiconductor substrate comprising a metal layer, a silicon nitride layer over the metal layer, and an oxide layer over the silicon nitride layer, wherein the metal layer comprises aluminum;

depositing an ultra-thin photoresist over the oxide layer, the ultra-thin photoresist having a thickness from about 500 Å

to about 2,000 Å

;

irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 200 nm or less;

developing the ultra-thin photoresist exposing a portion of the oxide layer;

etching the exposed portion of the oxide layer exposing a portion of the silicon nitride layer with a first etch chemistry being oxide;

photoresist selective;

etching the exposed portion of the silicon nitride layer exposing a portion of the metal layer with a second etch chemistry being both silicon nitride;

oxide selective and silicon nitride;

metal selective; and

etching the exposed portion of the metal layer with a third etch chemistry being metal;

silicon nitride selective thereby forming the metal line having a width of about 0.1 μ

m or less.

20. The method of claim 19, wherein the electromagnetic radiation has a wavelength of about 13 nm or about 11 nm.

21. The method of claim 19, wherein the metal layer has a thickness from about 5,000 Å

to about 10,000 Å

, the silicon nitride layer has a thickness from about 1,500 Å

to about 3,000 Å

, and the oxide layer has a thickness from about 2,000 Å

to about 5,000 Å

.

22. The method of claim 19, wherein the first etch chemistry being oxide:

photoresist selective comprises etch selectivity of at least about 4;

1.

23. The method of claim 19, wherein the second etch chemistry being silicon nitride:

oxide selective comprises etch selectivity of at least about 6;

1.

24. The method of claim 19, wherein the third etch chemistry being metal:

silicon nitride selective comprises etch selectivity of at least about 3;

1.

25. The method of claim 20, wherein the second etch chemistry comprises fluorine.

26. The method of claim 25, wherein the third etch chemistry comprises chlorine.