Method for removing etching residues and contaminants

• US 5,849,639 A
• Filed: 11/26/1997
• Issued: 12/15/1998
• Est. Priority Date: 11/26/1997
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Molloy, Simon John, Vitkavage, Daniel Joseph
• Primary Examiner(s): Breneman, R. Bruce
• Assistant Examiner(s): CHAMPAGNE, DONALD
• Application Number:
  US08/979,297
• Time in Patent Office: 384 Days
• Field of Search: 438/714, 438/906, 438/963, 134/1.2, 216/67
• US Class Current: 438/714
• CPC Class Codes: B08B 7/0035 by radiant energy, e.g. UV, laser, light beam or the like
• CPC Class Codes: G03F 7/427 using plasma means only
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: Y10S 438/906 Cleaning of wafer as interim step

Abstract

A gas plasma process for removing photoresist and etch residues and other contaminants involved in etching vias in integrated circuit devices is disclosed. The process involves placing the substrate having etched vias or contact holes in a suitable low bias reactor; applying to the substrate surface a mixture of gases at low bias selected from the group consisting of oxygen, nitrogen, fluorine, hydrofluorocarbon and fluorinated methane and amine gases to both remove the photoresist layer and alter the composition of the residues such that the residues are soluble in water; and rinsing the substrate with deionized water. The plasma process should be carried out at temperatures of less than about 100 degrees C to avoid mobile ion contamination problems and oxidation of the etch residues.

Claims

1. A photoresist strip and etch residue removal process comprising the steps of:

(a) providing an etched substrate having a photoresist layer and etchant residues;

(b) disposing the substrate in a reactor for applying a gas plasma over the surface of the substrate;

(c) etching the surface of the substrate using a mixture of gases to remove the photoresist layer and alter the composition of the etchant residues so that the residues are soluble in water, wherein the etching is performed with the temperature of the substrate maintained at less than about 100 degrees Centigrade; and

(d) rinsing the substrate with deionized water.

2. The process of claim 1, wherein the gases are selected from the group of oxygen, nitrogen, fluorine, hydrofluorocarbon, fluorinated methane, and amine gases.

3. The process of claim 1, wherein the etched substrate has via or contact holes for coupling interconnect layers of an integrated circuit device.

4. The process of claim 1, wherein the reactor is a downstream or remote plasma reactor operated at less than about 1500 W.

5. The process of claim 1, wherein the step of etching the substrate surface comprises an ion bombardment of the substrate surface at an energy level of less than about 50 eV.

6. The process of claim 1, wherein the mixture of gases comprise a plurality of gas mixtures selected from the group of (a) oxygen, nitrogen, and fluoromethane;

(b) oxygen, nitrogen, and tetrafluoromethane;

(c) oxygen, trifluoroamine and tetrafluoromethane;

(d) oxygen and trifluoroamine; and

(d) oxygen, trifluoroamine, and H₂ O (vapor).

7. The process of claim 1, wherein the mixture of gases is selected from the group consisting of about (a) 150-250 sccm O₂, 100-200 sccm N₂, and 150-250 sccm CH₃ F;

(b) 800-1000 sccm O₂, 50-200 sccm N₂, and 10-30 sccm CF₄ ;

(c) 900-1100 sccm O₂ and 20-40 sccm NF₃ ; and

(d) 700-900 sccm O₂, 20-40 sccm NF₃, and 150-250 sccm H₂ O (vapor).

8. The process of claim 7, wherein the step of etching the surface of the substrate comprises applying a gas mixture of about 200 sccm O₂, 150 sccm N₂, and 200 sccm CH₃ F over the substrate for about 60 seconds at 1400 W and 1.0 Torr;

applying a gas mixture of about 1000 sccm O₂, 100 sccm N₂, and 20 sccm CF₄ over the substrate for about 30 seconds at 1000 W at 0.7 Torr; and

applying a gas mixture of about 230 sccm O₂, 60 sccm NF₃, and 400 sccm CF₄ over the substrate for about 15 seconds at 1400 W and 1.00 Torr.

9. An improved method for removing photoresist and etch residues in a process of fabricating post vias and contact holes in a substrate for use in coupling interconnect layers of integrated circuit devices, the process being of the type where a photoresist layer is applied to selected portions of the substrate surface, leaving exposed portions, and a reactive etchant is applied to form vias or contact holes at the exposed portions of the substrate surface, the improvement comprising the steps of:

(a) disposing the substrate in a reactor for applying a gas plasma over the surface of the substrate;

(b) etching the surface of the substrate with a mixture of gases to remove the photoresist layer and alter the composition of the etchant residues so the residues are soluble in water, wherein the etching is performed with the temperature of the substrate maintained at about less than 100°

C.; and

(c) rinsing the substrate with deionized water.

10. The method of claim 9, wherein vertical or sloped post vias are etched in the substrate.

11. The method of claim 9, wherein the gases are selected from the group of oxygen, nitrogen, fluorine, hydrofluorocarbon, fluorinated methane, and amine gases.

12. The method of claim 9, wherein the reactor is a downstream or remote plasma reactor operated at less than about 1500 W.

13. The method of claim 9, wherein the step of etching the substrate comprises an ion bombardment of the substrate surface at an energy level of less than about 50 eV.

14. The method of claim 9, wherein the mixture of gases comprise a plurality of gas mixtures selected from the groups consisting of (a) oxygen, nitrogen, and fluoromethane;

(b) oxygen, nitrogen, and tetrafluoromethane; and

(c) oxygen, trifluoroamine and tetrafluoromethane;

(d) oxygen and trifluoroamine; and

(d) oxygen, trifluoroamine, and H₂ O (vapor).

15. The method of claim 9, wherein the mixture of gases is selected from the group consisting of about (a) 150-250 sccm O₂, 100-200 sccm N₂, and 150-250 sccm CH₃ F;

(b) 800-1000 sccm O₂, 50-200 sccm N₂, and 10-30 sccm CF₄ ;

(c) 900-1100 sccm O₂ and 20-40 sccm NF₃ ; and

(d) 700-900 sccm O₂, 20-40 sccm NF₃, and 150-250 sccm H₂ O (vapor).

16. The method of claim 9, wherein the step of etching the surface of the substrate comprises applying a gas mixture of about 200 sccm O₂, 150 sccm N₂, and 200 sccm CH₃ F over the substrate for about 60 seconds at 1000 W and 1.0 Torr;

and applying a gas mixture of about 1000 sccm O₂, 100 sccm N₂, and 20 sccm CF₄ over the substrate for about 30 seconds at 1000 W at 0.7 Torr.

17. The method of claim 16, further comprising applying a third gas mixture of about 230 sccm O₂, 60 sccm NF₃ and 400 sccm CF₄ over the substrate for about 15 seconds at 1400 W and 1.00 Torr.