Patent ID: 6449038
Filing Date: 2002-09-10
Classification: G01N,H01L

Abstract:
A substrate processing apparatus comprising:a process chamber capable of processing a substrate comprising a first material formed as a layer covering a plug and having a first reflectivity coefficient, and a second material about the plug that has a second reflectivity coefficient; a radiation source capable of emitting radiation that is reflected from the substrate during processing; a radiation detector to detect the reflected radiation and generate a signal trace; and a controller adapted to receive the signal trace and determine (i) an endpoint of processing the layer of first material and a startpoint of processing the plug of the first material from a change in the signal trace that is distinctive of an exposure of the plug of the first material and the second material having the second different reflectivity coefficient, and (ii) a depth of etching into the plug from periodic variations of the signal trace that correspond to maxima and minima interference peaks of the reflected radiation.