1.Every NDRF must be surrounded by unbroken P+ PICKUP AA.
(AA OR POLY) existing between NDRF and first P+ PICKUP AA ring of NDRF is not allowed.
这是SMIC40nm要求的。
2.但是,在TSMC180nm中,HVNW should be surrounded by HV N+OD ring(for HVNW pickup)and LV P+OD ring(for PW pick-up).
3.要求加两种ring,是预防闩锁。
问题:为什么SMIC40nm,要求(AA OR POLY) existing between NDRF and first P+ PICKUP AA ring of NDRF is not allowed.这样考虑的原因是什么?
而TSMC180nm,没有这个要求。