Wd. Wang et al., ADAPTIVE METROLOGY - AN ECONOMICAL STRATEGY FOR JUDGING THE ACCEPTABILITY OF A MASK PATTERN, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 13(6), 1995, pp. 2642-2647
Size and placement of all features in a mask used for semiconductor in
tegrated circuit manufacture must be within specified ranges for the m
ask to be acceptable. However the decision on whether the mask meets t
hese specifications is usually based on a limited set of measurements:
less than 1 in 10(6) of all possible sites. Conventional variance ana
lysis on such measurements is inadequate and often misleading because
mask pattern errors have significant systematic components. Here we de
scribe a more efficient metrology approach for determining whether a m
ask meets specifications, ''adaptive metrology'' where the results obt
ained as the measurements proceed are used to decide how many, and whe
re, more measurements are needed. The process is continued until there
is sufficient information to make a decision whether or not the mask
is acceptable. In this way the systematic component of the mask errors
can be exploited either to increase the accuracy of decisions or to s
horten the average measurement time for a given decision accuracy. (C)
1995 American Vacuum Society.