Patent ID: 6143667
Filing Date: 2000-11-07
Classification: H01L

Abstract:
A method of determining the endpoint of a dry etch process when the dry etch process is acting on a substrate comprising a layer of a first material overlying a second material, said method comprising:(a) illuminating said substrate with a beam of light wherein said beam of light has a wavelength that corresponds to a photon energy that is greater than the work function of one of said first and second materials, and less than the work function of the other material, such that only one of said first and second materials photoemits;(b) collecting a photocurrent, said photocurrent consisting essentially of photoelectrons emitted by the one of said first and second materials which is photoemitting;(c) amplifying said photocurrent; and(d) monitoring a temporal series of amplified photocurrent measurements for a change in the amplified photocurrent measurements known to correspond to an endpoint of the dry etch process.