Star-RC LEF/DEF Flow:
* LEF_FILE: technology LEF, standard cell LEF, and macro LEF.
* TOP_DEF_FILE: the top-level block design file in DEF format.
* TCAD_GRD_FILE: specifies the location of the TCAD GRD file containing conductor sheet resistances and models for 3-D parasitic capacitance calculation.
* MAPPING_FILE: specifies the mapping file, which maps the database layer to the tcad_grd layer.