This specific Pre Litho Cleaning step is located in the backside substrate contact (SBST_CONT) module, immediately following the deposition of the BPMD SiO layer and the underlying HKD/AR2 TaO and HKD/AR1 AlO layers A1.Unlike previous pre-litho cleans (such as steps #7, #13, #27, #49, and #73) which prepare front-side active area, gate, or interconnect layers, this distinct step conditions the backside passivation dielectric for deep contact photolithography A1.The primary function of this step