Work out etch rate and time instantly with clear inputs, formula shown and shareable results.
Etch time is target depth divided by etch rate, but selectivity and uniformity determine whether the result is usable: mask loss is depth divided by selectivity, and rate non-uniformity across the wafer means some die are over-etched while others are under-etched at the same endpoint.
Etch time
t = depth / rate; mask loss = depth / selectivity; variation = depth x non-uniformity
To clear residue in the slowest-etching regions. A 10% over-etch is typical, but it consumes more mask and can undercut or damage the underlying layer.
The chemistry's ability to attack the film while sparing the mask and the stop layer. High-aspect-ratio features also suffer from aspect-ratio-dependent etch slowdown.