OXIDE PLASMA ETCHING PROCESS WITH A CONTROLLED WINEGLASS SHAPE

• US 20010003678A1
• Filed: 07/22/1998
• Published: 06/14/2001
• Est. Priority Date: 07/22/1998
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: MERRY, WALTER R., BROOKS, CYNTHIA B., STINNETT, JAMES A., REGIS, JASON
• Granted Patent: US 6,355,557 B2
• Time in Patent Office: Days
• US Class Current: 438/723
• CPC Class Codes: H01L 21/76804 by forming tapered via holes

Abstract

An oxide etching method, particularly applicable to forming through an oxide layer a wineglass shaped contact or via hole of controlled shape. The wineglass hole is particularly useful for eased metal hole filling. The bowl is etched by first etching an anisotropic hole through a mask aperture, and then isotropically etching through the same mask aperture. The relative periods of the anisotropic and isotropic etch determine the lateral-to-vertical dimensions of the bowl. The stem is then etched through the same mask aperture with a strongly anisotropic etch. The isotropic etch may be performed in the same chamber as the anisotropic etch or may advantageously be performed in a separate etch chamber having a remote plasma source.

Claims

1. A method of etching a hole in dielectric layer having a mask formed thereover with a hole therethrough, comprising the steps of:

a first step of plasma etching said dielectric layer through said mask aperture in an anisotropic etching process;

a second step, after said first step, of plasma etching said dielectric layer through said mask aperture in an isotropic etching process producing less anisotropy than said first step; and

a third step, after said second step, of plasma etching said dielectric layer through said mask aperture in an anisotropic etching process.

2. The method of

claim 1

, wherein said dielectric layer overlies a substrate to be electrically contacted through said hole, and said third step etches through said dielectric layer.

3. The method of

claim 1

, wherein said first and third step includes RF biasing a pedestal holding said substrate more strongly than in said second step.

4. The method of

claim 3

, wherein said second step includes exciting a processing gas into a plasma with a remote plasma source.

5. The method of

claim 4

, wherein said dielectric layer comprises an oxide layer.

6. The method of

claim 5

, wherein a first processing gas used in said first step comprises a fluorocarbon gas and argon and a second processing gas used in said second step comprises a fluorocarbon gas and oxygen.

7. The method of

claim 6

, wherein said second processing gas additionally comprises NF₃.

8. The method of

claim 1

, wherein said dielectric layer comprises an oxide layer.

9. The method of

claim 8

, wherein said first step is performed with a fluorocarbon chemistry and wherein said second step includes a flow of oxygen.

10. The method of

claim 1

, wherein said first and second step are performed in a same plasma reaction chamber.

11. A method of etching a hole through a dielectric layer in a substrate, comprising the steps of:

a first etching step including RF biasing a pedestal supporting said substrate within a plasma reaction chamber, flowing a first etching gas into said chamber, and exciting a plasma within said chamber, wherein processing conditions in said first step produce a etching profile of said hole intermediate an isotropic etch and a strongly anisotropic etch to produce a first hole portion having a top wider than a bottom thereof; and

a second etching step performed subsequent to said first step including a strongly anisotropic etch of said hole through said oxide layer.

12. The method of

claim 11

, wherein said etching profile of the first step has sidewall angles of less than 80°

.

13. The method of

claim 12

, wherein said strongly anisotropic etch produces sidewall angles of greater than 85°

.

14. The method of

claim 11

, wherein said dielectric layer comprises an oxide layer.

15. The method of

claim 14

, wherein a processing gas used in said first step comprises a fluorocarbon gas and argon.