One chamber in-situ etch process for oxide and conductive material

• US 5,094,712 A
• Filed: 10/09/1990
• Issued: 03/10/1992
• Est. Priority Date: 10/09/1990
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Inman, Chris L., Becker, David S.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/595,119
• Time in Patent Office: 518 Days
• Field of Search: 252/79.1, 156/643, 156/646, 156/652, 156/653, 156/656, 156/567, 156/659.1, 156/662, 156/664, 156/667, 204/192.32, 204/192.35, 204/192.37
• US Class Current: 438/721
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/32105 Oxidation of silicon-containing layers
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

A method to anisotropically etch an oxide/silicide/poly sandwich structure on a silicon wafer substrate in-situ, that is, using a single parallel plate plasma reactor chamber and a single inert cathode. This method has an oxide etch step and a silicide/poly etch step, both of which are performed as plasma etch steps. The process allows a continuous etch to be applied without removing the wafer from the plasma reactor chamber. The fully etched sandwich structure has a vertical profile which has a controlled slope.

Claims

1. A method to anisotropically etch a wafer on which a dielectric, overlies a layer of silicide and silicon deposited over a substrate, comprising the steps of:

a) providing a parallel plate plasma etch reactor, having a first electrode whereupon the substrate is mounted, and having a second electrode that is non-erodible by plasma;

b) providing a first atmosphere within said reactor, containing CHF₃, CF₄, and an inert carrier gas;

c) exposing the dielectric layer to a plasma;

d) providing, within said reactor, an atmosphere containing He, O₂ and SF₆ ;

e) etching said silicide in said reactor by exposing the wafer to a plasma;

f) providing, within said reactor, an atmosphere containing HBr and Cl₂ ;

g) etching said silicon in said reactor by exposing the wafer to a plasma.

2. The method of claim 1, further comprising:

forming a protective passivation film, during the step of exposing the dielectric layer to a plasma, said film being formed by adjusting a ratio CF₄ and CHF₃ concentrations in order to control etch rate, selectivity, and anisotropy.

3. The method of claim 1, wherein:

said wafer is supported in the reactor by an O-ring which keeps the wafers from touching a lower electrode, and helium is applied to the back of the wafer, with the O-ring forming a barrier between the helium and the remainder of the reactor, thereby controlling cooling of the wafer.

4. The method of claim 1, wherein:

a) said first atmosphere has a pressure within approximately 0.3 to 10.0 torr, with a power density of plasma of approximately 3 to 300. W/cm² ;

b) said second atmosphere has a pressure within approximately 1.0 to 0.002 torr, with a power density of plasma of approximately 1.0 to 100. W/cm².

5. The method of claim 1, wherein:

said non-erodible second electrode is anodized aluminum.

6. A method to anisotropically etch a wafer on which a dielectric, overlies a layer of silicide and silicon deposited over a substrate, comprising the steps of:

a) providing a parallel plate plasma etch reactor, having a first electrode whereupon the substrate is mounted, and having a second electrode that is non-erodible by plasma;

b) providing a first atmosphere within said reactor, containing CHF₃, CF₄, and an inert carrier gas;

c) exposing the dielectric layer to a plasma;

d) following etching the dielectric layer, etching the silicide and silicon by etching in a second atmosphere, containing He, O₂ and SF₆, followed by etching in an atmosphere of 10 SCCM HBr and 50 SCCM Cl₂.

7. The method of claim 6, wherein:

the step of etching said silicide and silicon including etching in an atmosphere of approximately 10 SCCM He/O₂ and 30 SCCM SF₆, followed by etching in an atmosphere of 10 SCCM HBr and 50 SCCM Cl₂.

8. The method of claim 6, wherein:

a) said first atmosphere has a pressure within approximately 0.3 to 10.0 torr, with a power density of plasma of approximately 3 to 300. W/cm² ;

b) said second atmosphere has a pressure within approximately 1.0 to 0.002 torr, with a power density of plasma of approximately 1.0 to 100. W/cm².

9. The method of claim 6, wherein:

said non-erodible second electrode is anodized aluminum.

10. The method of claim 6, wherein:

The plasma power density of the etch in the second atmosphere is selected to provide a finished structure has a vertical profile at or near 85°

-90°

from horizontal.