Apparatus and plasma ashing process for increasing photoresist removal rate

• US 20060046470A1
• Filed: 09/01/2005
• Published: 03/02/2006
• Est. Priority Date: 09/01/2004
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Axcelis Technologies Incorporated
• Inventors: Ferris, David, Hammar, Philip, Becknell, Alan F.
• Granted Patent: US 7,449,416 B2
• Time in Patent Office: Days
• US Class Current: 438/637
• CPC Class Codes: G03F 7/427 using plasma means only
• CPC Class Codes: H01J 2237/3342 Resist stripping
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01J 37/32522 Temperature
• CPC Class Codes: H01L 21/0206 during, before or after processing of insulating layers
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors

Abstract

A plasma ashing process for removing photoresist material and post etch residues from a substrate comprising carbon, hydrogen, or a combination of carbon and hydrogen, wherein the substrate comprises a low k dielectric layer, the process comprising forming a plasma from an essentially oxygen free and nitrogen free gas mixture; introducing the plasma into a process chamber, wherein the process chamber comprises a baffle plate assembly in fluid communication with the plasma; flowing the plasma through the baffle plate assembly and removing photoresist material, post etch residues, and volatile byproducts from the substrate; periodically cleaning the process chamber by introducing an oxygen plasma into the process chamber; and cooling the baffle plate assembly by flowing a cooling gas over the baffle plate assembly. A process chamber adapted for receiving downstream plasma, the process chamber comprising an upper baffle plate comprising at least one thermally conductive standoff in thermal communication with a wall of the process chamber; and a lower baffle plate spaced apart from the upper baffle plate.

Claims

1. A plasma ashing process for removing photoresist material and post etch residues from a substrate including a low k dielectric material comprising carbon, hydrogen, or a combination of carbon and hydrogen, the process comprising:

forming a plasma from an essentially oxygen free and nitrogen free gas mixture;

flowing the plasma through a baffle plate assembly and onto the substrate and removing photoresist material, post etch residues, and volatile byproducts from the substrate;

flowing a cooling gas through an baffle plate assembly in a direction counter to the plasma flow and in an amount effective to reduce a temperature of the upper baffle plate.

2. The process of claim 1, wherein the baffle plate comprises an upper baffle plate and at least one additional baffle plate spaced apart from and coplanar to the upper baffle plate.

3. The process of claim 1, wherein the plasma comprises hydrogen and a noble gas.

4. The process of claim 3, wherein the noble gas is helium.

5. The process of claim 1, wherein flowing the cooling gas in the direction counter to the plasma flow is at a flow rate of 15 liters per minute to about 100 liters per minute at standard temperature and pressure conditions.

6. The process of claim 1, wherein flowing the cooling gas further comprises simultaneously heating the substrate.

7. The process of claim 1, wherein the cooling gas comprises an inert gas.

8. The process of claim 1, wherein the cooling gas is selected from the group consisting of helium, argon, hydrogen and mixtures thereof.

9. The process of claim 2, wherein the at least one additional baffle plate spaced apart from and coplanar to the upper baffle plate comprises a plurality of apertures disposed about a central axis increasing in density from the central axis to an outer edge of the at least one baffle plate.

10. The process of claim 2, wherein the upper baffle plate assembly further comprises an impingement plate disposed in physical communication with a center portion of the upper baffle plate.

11. The process of claim 1, wherein the removing the photoresist material, the post etch residues, and the volatile byproducts from the substrate is at an ash rate greater than an ash rate in the absence of the cooling gas flow.

12. The process of claim 1, wherein the at least one additional baffle plate spaced apart from and coplanar to the upper baffle plate comprises a plurality of apertures disposed about a central axis increasing in diameter from the central axis to an outer edge of the at least one baffle plate.

13. A plasma ashing process for removing photoresist material and post etch residues from a substrate comprising carbon, hydrogen, or a combination of carbon and hydrogen, wherein the substrate comprises a low k dielectric layer, the process comprising:

forming a plasma from an essentially oxygen free and nitrogen free gas mixture, wherein the plasma comprises hydrogen and helium;

flowing the plasma into a process chamber, wherein the process chamber comprises a baffle plate assembly in fluid communication with the plasma, wherein the baffle plate assembly comprises a generally planar upper baffle plate fixedly positioned above a generally planar lower baffle plate, the lower baffle plate comprising a plurality of apertures disposed about a central axis, wherein the plurality of apertures increase in density from the central axis to an outer edge of the lower baffle plate;

periodically cleaning the process chamber by introducing an oxygen plasma into the process chamber; and

cooling the baffle plate assembly by flowing a cooling gas at and about a central impingement region of the upper baffle plate.

14. The process of claim 13, wherein flowing the cooling gas over the baffle plate assembly is at a flow rate of 15 liters per minute to 100 liters per minute at standard temperature conditions.

15. The process of claim 13, wherein flowing the cooling gas over the baffle plate assembly is in a direction counter to the plasma flow.

16. The process of claim 13, wherein the cooling gas comprises an inert gas.

17. The process of claim 13, wherein the cooling gas is selected from the group consisting of helium, argon, hydrogen and mixtures thereof.

18. A process chamber adapted for receiving plasma, the process chamber comprising:

a baffle plate assembly comprising a generally planar upper baffle plate positioned above a generally planar lower baffle plate, the lower baffle plate, the upper baffle plate comprising at least one thermally conductive standoff in thermal communication with a wall of the process chamber.

19. The process chamber of claim 18, wherein the wall of the process chamber is water-cooled.

20. The process chamber of claim 18, wherein the upper baffle plate is formed of a thermally conductive material.

21. The process chamber of claim 18, wherein the upper baffle plate is formed of aluminum.

22. A downstream plasma asher comprising the process chamber of claim 18.