For almost all fabrication processes, numerical simulators are available that compute the effects of a given process step or treatment on the wafer. The wafer is represented as some kind of data model in one, two, or three dimensions, depending on the nature of the problem to solve. Some simulators are specialized on one kind of process step, e.g., lithography simulators [KS96] concentrate on the light-propagation and resist-bleaching phenomena during exposure, while others are capable of computing a sequence of related process steps [Ele91] [STHN91] [WN95] or complete process flows including etching, deposition, ion implantation, and thermal treatments [Tec95].
The level of abstraction for specifying a fabrication step
varies from tool to tool. E.g., etch and deposition
processes in SUPREM [Tec95] are specified on an
effects-basis, i.e., the user has to pass the expected effect in
terms of the thickness of material removed to the program, whereas
the etch and deposition modules PROMIS [SS93] [Str94]
and SAMPLE [Ele91] expect etch and deposition rates to
be given
.
Therefore, a clear correspondence between process step parameters and
simulator input in general cannot be defined easily.