A thin FinFET Si-fin body structure fabricated with 193nm scanner photolithography and composite hard mask etching technique upon bulk-Si substrate

Abstract

A thin FinFET bulk Si-fin body structure has been successfully fabricated upon bulk-Si wafers through using 193nm scanner lithography and a composite hard mask etching technique. First, a 100 angstrom-thick buffer SiO2 layer was thermally grown upon the bulk silicon layer and subsequently a 1200 angstrom-thick SiNx layer and a 1000 angstrom-thick TEOS SiO2 hard mask layer was chemically vapor deposited to form a composite hard mask structure of buffer-SiO2/SiNx/TEOS. Second, both 1050 angstrom-thick BARC and 2650 angstrom-thick photoresist (P/R) were coated and a 193nm scanner lithography tool was used for the Si-fin body layout patterning under relatively high exposure energy. This achieves the ADI (after develop inspection) of 80nm from the original as-drawn Si-fin layout of 110nm. Then, a deep sub-micron plasma etcher was used for an aggressive P/R and BARC trimming down processing and both the capping TEOS and CVD-SiNx with its underlying buffer oxide layers were subsequently etched in other etching plasma chambers, respectively. Resultantly, the AMI (after mask inspection) can reach 60nm. Subsequently, both the P/R and BARC were removed with a nominal plasma ashing as well as a RCA cleaning for the final sub-micron Si-fin plasma etching. Eventually, a 60nm-width and 400nm-height bulk Si-fin body structure can be successfully etched out after a fixed time-mode silicon plasma etching.