Patent ID: 6632321
Filing Date: 2003-10-14
Classification: H01J,H01L

Abstract:
Apparatus for controlling a wafer processing system having a chamber and a pedestal within said chamber, the apparatus comprising:an interferometer for generating a signal indicative of a rate of an aspect ratio dependent etch (ARDE) occurring within said chamber; and a controller coupled to said interferometer and said wafer processing system, for varying one or more process parameters of said wafer processing system in response to said signal, wherein the controller comprises a memory and an etch rate processing routine to control the rate of the aspect ratio dependent etch, the etch rate processing routine being capable of executing the steps of: retrieving a predetermined etch rate schedule from the memory of the controller, the predetermined etch rate schedule comprising a function of desired aspect ratio dependent etch rate over time; mesuring an actual aspect ratio dependent etch rate by measuring the elapsed time between two conjugate maxima or minima points of the signal generated by the interferometer; comparing the actual aspect ratio dependent etch rate to the desired aspect ratio dependent etch rate in the retrieved predetermined etch rate schedule; and varying one or more of the process parameters of the wafer processing system to change the actual aspect ratio dependent etch rate occurring in the chamber to substantially follow the desired aspect ratio dependent etch rate.