Browse Prior Art Database

RIE Etch End Point Detector for Variably Doped Silicon: Optical Spectrometer

IP.com Disclosure Number: IPCOM000052507D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Barbee, SG: AUTHOR [+2]

Abstract

A spectrophotometer coupled to a photodetector can be used to monitor and stop the reactive ion etching (RIE) of silicon at a predetermined end point. Silicon used in transistor applications has a variation in the concentration and type of doping impurities. In the usual case, the doping impurities consist of layers of arsenic and boron. Photodetectors can be set to look for the characteristic lines of arsenic and boron. The depth of the etch can be determined by the intensity of the line if the doping profile of the silicon is known. The desired etch end point is a certain point in the doping profile.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

RIE Etch End Point Detector for Variably Doped Silicon: Optical Spectrometer

A spectrophotometer coupled to a photodetector can be used to monitor and stop the reactive ion etching (RIE) of silicon at a predetermined end point. Silicon used in transistor applications has a variation in the concentration and type of doping impurities. In the usual case, the doping impurities consist of layers of arsenic and boron. Photodetectors can be set to look for the characteristic lines of arsenic and boron. The depth of the etch can be determined by the intensity of the line if the doping profile of the silicon is known. The desired etch end point is a certain point in the doping profile.

The use of optical spectrophotometry has several advantages. The variability in doping profile from run to run can be compensated for, and the depth of etch can be tailored to the requirements of the particular wafers being etched. Another advantage is that several regions can be examined inside the reactive ion etch chamber to measure uniformity of reactive ion etching. By focusing the photodetector lens along the line of sight into the chamber, instantaneous information on the depth of etch is provided.

1