Method for tapered etching

• US 4,919,748 A
• Filed: 06/30/1989
• Issued: 04/24/1990
• Est. Priority Date: 06/30/1989
• Status: Expired due to Term

• Current Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Original Assignee: AT&T, Inc.
• Inventors: Giniecki, Troy A., Stocker, Hans J., Bredbenner, Craig N., Selamoglu, Nur
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/374,408
• Time in Patent Office: 298 Days
• Field of Search: 252/79.1, 156/643, 156/644, 156/646, 156/652, 156/656, 156/659.1, 156/661.1, 156/664, 156/665, 204/192.32, 204/192.35, 427/38, 427/39, 430/313, 430/318
• US Class Current: 438/656
• CPC Class Codes: C23F 4/00 Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
• CPC Class Codes: H01L 21/02071 the processing being a delineation, e.g. RIE, of conductive layers

Abstract

A method for etching metal layers including aluminum to create tapered sidewalls is disclosed. The method features the use of trifluoromethane and chlorine in controlled amounts to create a tapered metal layer profile.

Claims

1. A method of semiconductor device fabrication comprising:

forming a first layer upon a substrate;

forming a second layer containing aluminum upon said first layer;

etching both said first and said second layer with a gas mixture, characterized in that said gas mixture contains chlorine and trifluoromethane and said etching step produces a tapered profile.

2. The method of claim 1 in which said gas mixture further contains boron trichloride.

3. The method of claim 1 in which said etching occurs in a plasma environment.

4. The method of claim 1 wherein said first layer is made from a material chosen from the group consisting of:

titanium- tungsten and titanium nitride.

5. The method of claim 1 in which the flow ratio of said trifluoromethane and chlorine is at least 0.75.

6. A method of semiconductor device fabrication comprising:

depositing a layer of titanium-tungsten upon a substrate, said layer containing at least five percent titanium by weight;

depositing an aluminum rich layer upon said layer of titanium-tungsten layer;

covering said aluminum rich layer with an anti reflective coating;

covering said anti reflective coating with a patterned mask, said mask having a thickness of 2 μ

m or less;

exposing said aluminum rich layer to boron trichloride;

exposing said aluminum rich layer said titanium-tungsten layer in a plasma environment to a mixture of chlorine and trifluoromethane, said chlorine having a flow rate of between 16 and 6 sccm and said trifluoromethane having a flow rate less than 60 sccm, said exposing step creating a polymeric layer in contact with said aluminum rich layer and said titanium tungsten layer and creating a tapered sidewall on said aluminum rich layer and said titanium-tungsten layer;