For production use, a semiconductor process description contains a sequence of
process steps to be carried out on the wafer substrate, with
additional constraints and target values for certain physical and
electrical parameters measured during fabrication. During process
development, on the other hand, process engineers wish to specify
conditional statements, loops, and branch operation in a fashion
similar to writing computer programs.
However, in order to separate the nominal
process description from experimental alterations, modifications to
the process flow can be assigned externally, using step names and
parameter names and leaving the process flow description
file unchanged
.
See Section 8.4.1 for details.