Method for end point detection in a plasma etching process

• US 4,328,068 A
• Filed: 07/22/1980
• Issued: 05/04/1982
• Est. Priority Date: 07/22/1980
• Status: Expired due to Term

• Current Assignee: Intersil Corporation (Renesas Electronics Corporation)
• Original Assignee: RCA Corporation
• Inventors: Curtis, Bernard J.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US06/171,271
• Time in Patent Office: 651 Days
• Field of Search: 356/316, 356/326, 356/338, 356/346, 356/437, 356/445, 204/164, 204/192 EC, 204/192 E, 204/298, 250/531, 427/39, 427/10, 118/712, 118/620, 156/345, 156/626, 156/627, 156/643, 156/646
• US Class Current: 216/60
• 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: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

An improved plasma etching apparatus having a light pipe inserted through the chamber wall for coupling light emitted by different chemical species out of the chamber. The light pipe collects the emission directly or after reflection from the coated surface of a substrate. Stabilization of the intensity of the collected emission is indicative of the end point of the etching process.

The invention includes a method for detecting the end point of the etching process by monitoring the intensity of light emitted by a component of a gas contained in the chamber which passes out of the chamber through the light pipe. The light may be coupled directly into the light pipe or the light pipe may be so positioned as to detect the emitted light after it is reflected from the surface of the substrate. The intensity of the light is monitored until it stabilizes, indicating that the etching process is complete.

Claims

1. In a method for measuring the end point of a plasma etching process comprising mounting a light pipe in the wall of a plasma chamber, which light pipe extends from outside to within the chamber, positioning a substrate having a coating thereon, a portion of which is to be removed by plasma etching, in the chamber, positioning a light detector and a wavelength bandpass filter so as to detect light of a certain wavelength passing through the light pipe, flowing a reactive gas into the plasma chamber, initiating a plasma discharge in the reactive gas, monitoring the intensity of the light passing through the light pipe until the intensity stabilizes, and terminating the plasma discharge;

the improvement comprising positioning the end of the light pipe within the chamber so that light of said wavelength emitted by a chemical species present in the plasma discharge is reflected from the coated surface of the substrate before passing into the end of the light pipe.