DRC rules. The substitutions are specified by "%d" for the main
rule distance, "%c" for the corner rule distance (sometimes
interpreted differently; e.g., as width in the widespacing rule),
and "%a" for rule area (e.g., maxarea rule). In addition to
simplifying the process of writing rule violation strings, the
benefits are twofold: (1) The output is in meaningful physical
units, but in the case of SCMOS technology, will scale properly
depending on the selected GDS output style, and in the case of
all technologies, will scale properly with internal grid division;
and (2) when using lambda, but where rules are given in vendor
minimum dimensions, the rules will be based on the lambda rule
approximation (that is, distances will be rounded to the nearest
lambda but reported in microns). Behavior is unchanged from
previous versions for "why" strings not using the defined
substitution sequences.
errors from the area checked must use the same area as is used
by the interaction checker to recompute errors. In earlier code,
both these areas were much larger than necessary. In the last
code update, the area to make revised checks was reduced, but
the area cleared of errors was not, resulting in errors that
would disappear from the layout as paint changes were made, until
a full "drc check" was run again. This code commit makes the
areas the same again so that no errors are lost.
much larger area than necessary to the interaction check, and
the other which failed to scale the tech halo distance down
after scaling all the rules. Both of these led to huge areas
of a layout being unnecessarily checked when even a tiny part
of the layout was modified. Corrected behavior matches
expectations for interactive DRC response.
avoid the problem where subcells violate DRC themselves but do
not violate DRC in the context of the parent (i.e., the parent
adds metal to avoid minimum area error), DRC errors in subcells
are neither counted nor displayed, but they remain present in
the subcell database. The DRC check enumerates all subcell
errors as mandatory check areas in DRCFindInteractions(), so
that those areas are always counted with the interaction areas.
Previously, if a subcell violated a DRC rule by itself, that
error would be counted and displayed in the parent even if the
parent had paint causing the error to no longer exist.
Tim Edwards