Method for the optical monitoring of plasma discharge processing operations

• US 4,312,732 A
• Filed: 03/10/1980
• Issued: 01/26/1982
• Est. Priority Date: 08/31/1976
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Degenkolb, Eugene O., Mogab, Cyril J., Griffiths, James E.
• Primary Examiner(s): Weisstuch, Aaron
• Application Number:
  US06/128,837
• Time in Patent Office: 687 Days
• Field of Search: 204/164, 204/192 E, 204/298, 156/345, 156/643, 356/437, 356/72
• US Class Current: 204/192.33
• CPC Class Codes: G01N 21/62 Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

The endpoints of plasma discharge processing operations (e.g., plasma stripping of photoresists and plasma etching) are determined by monitoring the light produced in the space surrounding the object being processed. The optical monitor includes a wavelength selective device which is adjusted to transmit light from a selected excited species, which includes particles from the surface being processed. The surface includes a layer of one material overlaying a second material. If the selected excited species includes particles of the first material, then the endpoint of the removal operation occurs when the monitored intensity falls below a predetermined threshold level. When the selected excited species includes particles of the second material, then the endpoint occurs when the monitored intensity rises above a preselected threshold level.

Claims

1. A method for fabricating a device comprising the steps of

(a) subjecting a body to a plasma discharge wherein said body comprises a resist material in intimate contact with an underlying material in a substrate body;

(b) passing a portion of the electromagnetic radiation produced by said plasma discharge into a radiation detector which produces an output signal dependent upon the intensity of said portion of radiation; and

(c) removing said body from contact with the plasma discharge after said output signal passes a predetermined threshold value characterized in that the portion of electromagnetic radiation is a frequency limited portion of half width no greater than 150 Angstroms including radiation of a frequency corresponding to radiation from a preselected excited species including particles resulting from chemical combination of entities from said body with entities from said plasma discharge.

2. The process of claim 1 wherein said resist material comprises a photoresist layer.

3. The process of either claim 1 or 2 wherein said particles resulting from chemical combinations emanate from the reaction of entities from said plasma discharge with said resist material.

4. The process of claim 1 wherein said body comprises a metal.

5. The process of claim 1 wherein said body comprises a semiconductor material.