Dry etching method

• US 5,685,950 A
• Filed: 07/15/1996
• Issued: 11/11/1997
• Est. Priority Date: 12/29/1993
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sato, Junichi
• Primary Examiner(s): DANG, THI D
• Application Number:
  US08/680,103
• Time in Patent Office: 484 Days
• Field of Search: 156/643.1, 156/646.1, 156/662.1
• US Class Current: 438/713
• CPC Class Codes: H01L 21/02071 the processing being a delineation, e.g. RIE, of conductive layers

Abstract

A dry etching method is disclosed in which a first polysilicon layer is etched, using an ECR plasma of an etching gas containing a bromine-based gas and a rare gas, as a sidewall protective film is formed by a deposit mainly composed of SiBr, for forming a tapered gate electrode. Since SiBr_x is efficiently generated by a radical reaction of Br^* assisted by an ion-assist mechanism by the rare gas, and has a long residence time under a low gas pressure, it can be deposited efficiently on a patterned sidewall surface. Since the sidewall protective film produced with the present dry etching method, is free of SiO_x, particle contamination may be diminished. Since post-processing of a shorter time duration suffices for removing the sidewall protective film, erosion of the gate insulating film is not produced. Thus the semiconductor device having the fine multi-layer interconnection structure may be improved in reliability and yield.

Claims

1. A method for dry etching of a layer of silicon-based material on a substrate comprising the steps of:

forming a mask layer on the layer of the silicon-based material for exposing an area to be etched;

etching the exposed area by providing an etching gas consisting of a bromine-based gas, an oxygen-based gas and a rare gas with a rate of flow of the rare gas being more than a rate of flow of the bromine-based gas, creating an ECR plasma with the etching gas under a gas pressure of 1.3 to 13.3 Pa to etch the exposed area while depositing a deposit composed mainly of silicon bromide on sidewalls created by the etching and controlling the amount of oxygen-based gas to limit the amount of oxygen in the deposit, and then

removing the deposit on the sidewalls with a fluorine plasma process.

2. A method according to claim 1, wherein said etching produces an etched silicon-based layer with a tapered cross-section.

3. A method according to claim 1, wherein the fluorine plasma process used a NF₃ gas plasma.

4. A method according to claim 1 which include preforming the etching step in a magnetic micro-wave plasma etching device and the method includes transporting the etched substrate from the plasma etching device to a post-processing chamber where the step of removing is preformed.

5. A method according to claim 1 wherein the rare gas is argon.

6. A method according to claim 5 wherein the step of etching is performed in a chamber of a magnetic microwave plasma electron device and the method includes transporting the etched substrate from the etching device to a post-processing chamber where the step of removing is preformed.

7. A method for dry etching of a layer of silicon-based material on a substrate comprising the steps of:

forming a mask layer on the layer of the silicon-based material for exposing an area to be etched;

etching the exposed area by providing an etching gas consisting of a bromine-based gas and a rare gas with a rate of flow of the rare gas being more than a rate of flow for the bromine-based gas, creating an ECR plasma with the etching gas under a gas pressure of 1.3 to 13.3 Pa to etch the exposed area while depositing a deposit composed mainly of silicon bromide on sidewalls created by the etching, and then

removing the deposit of silicon bromide by a fluorine plasma process.

8. A method according to claim 7 wherein said etching produces an etched silicon-based layer with a tapered cross-section.

9. A method according to claim 7 wherein the fluorine plasma process uses a NF₃ gas plasma.

10. A method according to claim 7, wherein the rare gas is argon.

11. A method according to claim 10 which include preforming the etching step in a magnetic micro-wave plasma etching device and the method includes transporting the etched substrate from the plasma etching device to a post-processing chamber where the step of removing is preformed.

12. A method according to claim 7 wherein the step of etching is performed in a chamber of a magnetic microwave plasma electron device and the method includes transporting the etched substrate from the etching device to a post-processing chamber where the step of removing is preformed.