What is the option of the process that is used? Based on what I can find I would say 1P5M (TM 9KA with MIM), but I don't see it mentioned anywhere.

its mcuC

I believe that is not what the actual metal stack is called. This is how efabless refers to it, but underlying there must be something from this list: https://gf180mcu-pdk.readthedocs.io/en/latest/analog/layout/inter_specs/inter_specs.html

https://github.com/mabrains/globalfoundries-pdk-libs-gf180mcu_fd_pr/blob/8fc42ddf1c5d1ff60fbaa0e87158127c20bc4a6d/rules/klayout/drc/run_drc.py#L310 shows gf180mcuC as being 9K top metal, MIM option B, 5LM stack

Yes, that's correct. 5-metal stack (5LM), 0.9um thick metal 5 (TM 9KA, which means 9kAngstroms, or 0.9um), MiM option B (MiM cap between top metal and the metal below it, i.e., M5 to M4), and also (not mentioned above) 1kOhm high sheet rho poly, and 2fF/um^2 MiM capacitance options. By the way, the "A", "B", "C" designation is mine, from

open_pdks

. It corresponds to the way that

open_pdks

builds PDK directories, which is to provide a complete set of files for each of some number of predefined combinations of options. To avoid redundancy, files that are the same between different PDK variants are just symbolic links back to the first variant. The definition of the options corresponding to each variant can be found in the file

<process>/Makefile.in

(e.g.,

gf180mcu/Makefile.in

). I keep the

Makefile

well-commented at the top so that it's pretty easy to read through it and figure out what all the option definitions mean. The final word on the options are the lines:

# Module definitions for each process node (see top)
GF180MCUA_DEFS += -DMETALS3 -DMIM -DTHICKMET3P0 -DHRPOLY1K
GF180MCUB_DEFS += -DMETALS4 -DMIM -DTHICKMET1P1 -DHRPOLY1K
GF180MCUC_DEFS += -DMETALS5 -DMIM -DTHICKMET0P9 -DHRPOLY1K