Patent ID: 6649075
Filing Date: 2003-11-18
Classification: H01J

Abstract:
A method for measuring uniformity of a surface of a wafer as a result of an etching process comprising the steps of:acquiring data indicating etch progression, wherein said data represents an intensity of an emission at a monitored wavelength of light; defining a trigger criterion corresponding to a particular value of said data to form a trigger point; producing, as said data is acquired, a first derivative of said data as a first derivative value, wherein said first derivative value is produced by X2-X1Î”&it;â€ƒ&it;Twhere X1 is a data point in said data, and X2 is a data point and &Dgr;T is a time duration elapsed between acquisition of the and data points, said trigger criterion is a peak of said first derivative; andgenerating, when said trigger criterion is attained by said data, a uniformity value representing the uniformity of the surface of the wafer by directly correlating said first derivative value to said uniformity value.