Appeal No. 2002-0453
Serial No. 08/686,229
THE INVENTION
The appellants claim a method for measuring uniformity of
the surface of a wafer as a result of an etching process.
Claim 1 is illustrative:
1. 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
where X1 is a data point in said data, and X2 is a data point and
)I is a time duration elapsed between acquisition of the X1 and
X2 data points, said trigger criterion is a peak of said first
derivative; and
generating, 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.
THE REFERENCES
Schoenborn 5,362,356 Nov. 8, 1994
G.E.F. Sherwood and Angus E. Taylor (Sherwood), Calculus 20-21
(Prentice-Hall, 3rd ed. 1954).
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