Process for isotropically etching semiconductor devices

• US 5,358,601 A
• Filed: 09/14/1993
• Issued: 10/25/1994
• Est. Priority Date: 09/24/1991
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Cathey, David A.
• Primary Examiner(s): Breneman, R. Bruce
• Assistant Examiner(s): GOUDREAU, GEORGE A
• Application Number:
  US08/121,089
• Time in Patent Office: 406 Days
• Field of Search: 156/646, 156/643, 156/662, 156/659.1, 156/656, 156/657, 156/664
• US Class Current: 438/721
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

The etchant material of this invention comprises a chemical etchant composition including a halogen-containing feed gas and gaseous carbon dioxide. Typically, the halogen-containing feed gas is a fluorine-containing or a chlorine-containing feed gas, or both a fluorine-containing and a chlorine-containing feed gas. Preferably, the chlorine-containing feed gas comprises chlorine gas or HCl, and the fluorine-containing feed gas comprises SF₆ or NF₃. The fluorine-containing feed gas can also comprise CF₄, or C2F₆.

Claims

1. A process for controllably, isotropically etching a semiconductor device to form an etched pattern therein, comprising:

a) providing a semiconductor device having a plurality of structural layers, one of the outer structural layers of the semiconductor device comprising a tungsten polysilicide layer on a polysilicon layer;

b) forming on a top surface of the semiconductor device a protective etch mask defining a plurality of openings, said plurality of openings exposing a plurality of areas of the top surface of the semiconductor device;

c) controllably isotropically etching the plurality of exposed areas of the top surface of the semiconductor device with an etchant material to form an etched profile in which the tungsten polysilicide layer and the polysilicon layer are etched at similar etch rates to form a similar etch profile, and producing a tungsten polysilicide/polysilicon profile having vertical sides and having resist overhang projecting laterally from the vertical sides of the tungsten polysilicide/polysilicon profile;

d) the etchant material comprising a chemical etchant composition including NF₃, a gaseous carbon dioxide; and

at least one of chlorine gas and HCL.

2. A process for controllably, isotropically plasma etching a semiconductor device to form an etched pattern therein, comprising:

a) providing a semiconductor device having a plurality of structural layers, one of the outer structural layers of the semiconductor device comprising a tungsten polysilicide layer on a polysilicon layer;

b) forming on a top surface of the semiconductor device a protective etch mask defining a plurality of openings, said plurality of openings exposing a plurality of areas of the top surface of the semiconductor device;

c) controllably isotropically etching the plurality of exposed areas of the top surface of the semiconductor device with an etchant material to form an etched profile in which the tungsten polysilicide layer and the polysilicon layer are etched at similar etch rates to form a similar etch profile, and producing a tungsten polysilicide/polysilicon profile having vertical sides and having resist overhang projecting laterally from the vertical sides of the tungsten polysilicide/polysilicon profile;

d) the etchant material comprising a chemical etchant composition including a chlorine-containing material, a gaseous carbon dioxide, and a fluorine-containing material;

e) the fluorine-containing material being CF₄ ; and

f) the chlorine-containing material is selected from the group consisting of chlorine gas or HCL.

3. A process for controllably, isotropically plasma etching a semiconductor device to form an etched pattern therein, comprising:

a) providing a semiconductor device having a plurality of structural layers, one of the outer structural layers of the semiconductor device comprising a tungsten polysilicide layer on a polysilicon layer;

b) forming on a top surface of the semiconductor device a protective etch mask defining a plurality of openings, said plurality of openings exposing a plurality of areas of the top surface of the semiconductor device;

c) controllably isotropically etching the plurality of exposed areas of the top surface of the semiconductor device with an etchant material to form an etched profile in which the tungsten polysilicide layer and the polysilicon layer are etched at similar etch rates to form a similar etch profile, and producing a tungsten polysilicide/polysilicon profile having vertical sides and having resist overhang projecting laterally from the vertical sides of the tungsten polysilicide/polysilicon profile;

d) the etchant material comprising a chemical etchant composition including, a chlorine-containing material, a gaseous carbon dioxide, and a fluorine-containing material;

e) the fluorine-containing material comprising C₂ F₆ ; and

f) the chlorine-containing material is selected from the group consisting of chlorine gas or HCL.

4. A process for using a plasma etchant material for isotropically plasma etching a semiconductor device to form an etched pattern therein, comprising:

a) providing an etchant material comprising a chemical etchant composition including a fluorine-containing material, a chlorine-containing material and gaseous carbon dioxide;

b) providing a semiconductor device having a plurality of structural layers, one of the outer structural layers of the semiconductor device comprising a tungsten polysilicide layer on a polysilicon layer;

c) forming on a top surface of the semiconductor device a protective etch mask defining a plurality of openings in a pattern, said plurality of openings exposing a plurality of areas of the top surface of the semiconductor device;

d) controllably isotropically plasma etching the plurality of exposed areas of the top surface of the semiconductor device with an etchant material to form an etched profile in which the tungsten polysilicide layer and the polysilicon layer are etched at a similar etch rate to form a similar etch profile, and producing a tungsten polysilicide/polysilicon profile having vertical sides and having resist overhang projecting laterally from the vertical sides of the tungsten polysilicide/polysilicon profile; and

e) the fluorine-containing material is selected from the group consisting of C₂ F₆.