Comment amtetcher SNF 2010-10-11 11:33:28: si etch rate is off

etched asml alignment marks into poly. the etch rate is much slower than past runs and also not consistent from session to session and not uniform within a wafer.
etch data-
target: 1200A etch into poly
program 4
previous run as reference:
5min -> ~1200A +/- <100A
10/8 test etch #1:
5min -> 700A-770A (much slower etch rate)
10/8 test etch #2:
7.8min -> 1224-1296A (fairy consistent with etch #1 rate)
10/8 actual etch:
7.8min etch
wafer 1: 1398 - 1748A (non-uniform and inconsistent with test etch #2)
wafer 2: 2000 - 3800A (inconsistent with wafer 1 and test etch #2 and very non-uniform)