RIE Etch End Point Detector for Variably Doped Silicon: Optical Spectrometer
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
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.