Dry etching method

• US 5,266,154 A
• Filed: 04/27/1992
• Issued: 11/30/1993
• Est. Priority Date: 04/26/1991
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Tatsumi, Tetsuya
• Primary Examiner(s): DANG, THI D
• Application Number:
  US07/874,114
• Time in Patent Office: 582 Days
• Field of Search: 156/643, 156/646, 156/345, 156/662
• US Class Current: 216/67
• CPC Class Codes: H01J 2237/3345 anisotropy
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32477 characterised by the means for protecting vessels or internal parts, e.g. coatings
• CPC Class Codes: H01J 37/32678 Electron cyclotron resonance
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

A dry etching method whereby underlying layer selectivity and anisotropy may be prevented from deteriorating due to excessive radicals in an over-etching process. In the etching chamber of an ordinary magnetically-enhanced microwave plasma etching apparatus, the so-called ECR position at which the ECR condition is established is a very small region, where ionization current has the highest density and the most uniform direction in ECR plasma. On the downstream side of the ECR position is the after-glow region of ECR plasma with a low plasma density. According to the present invention, the etching chamber is provided on part of the inner sidewall thereof with an Si-based material layer capable of consuming halogen radicals while a lifting and lowering means is provided for varying the distance between a target wafer and the ECR position. In a just-etching process, the wafer is kept close to the ECR position so that it may be etched at a high rate in an anisotropic shape by radicals with a high density and ions with a uniform direction. In an over-etching process, the wafer is kept distant from the ECR position to bring the after-glow region into contact with the Si-based material layer, which captures excessive radicals such as F* in the form of SiF_x for removal from an etching reaction system. Thus, the present invention can be applied to polysilicon gate electrode processing to improve gate insulation film selectivity.

Claims

1. A dry etching method comprising the steps of providing an ECR etching apparatus whose etching chamber has at least one portion of the inner sidewall thereof covered with a silicon-based material layer on a downstream side of an ECR position and which apparatus is capable of varying the distance between said ECR position and a target substrate;

etching a target material layer of the target substrate with said target substrate kept relatively close to said ECR position; and

then over-etching said target material layer with said target substrate being moved away from said ECR position to expose portions of the silicon-based material layer to the etching gases.

2. A dry etching method as claimed in claim 1, wherein said etching proceeds under the influence of halogen radicals.

3. A dry etching method as claimed in claim 1, wherein said target material layer is based on silicon or compound thereof.

4. A dry etching method comprising the steps of providing an ECR etching apparatus having an etching chamber having an ECR position at one end of the chamber and having silicon-based material disposed adjacent the opposite end of the chamber with a target substrate support being movable from a position adjacent the ECR position to a position exposing portions of the silicon-based material adjacent the opposite end;

creating a plasma in said etching chamber and etching a material layer of the target substrate with said target substrate being in a first position relatively close to said ECR position;

moving the target substrate away from said first position to expose portions of the silicon-based material to the plasma and then over-etching said target material layer.

5. A dry etching method according to claim 4, wherein the etching proceeds under the influence of halogen radicals.

6. A dry etching method according to claim 4, wherein the target material is based on a silicon or silicon compound.