Fabrication of submicrometer CMOS circuits using a new trilayer photolithographic process

CMOS circuits with submicrometer gate lengths were fabricated using a new trilayer photolithographic process. A transparent and electrically conductive film of indium tin oxide was used as the middle layer in the trilayer resist with unique advantages. The shortest on-mask gate length for which CMOS circuits were successfully fabricated was 0.75 µm. The corresponding effective channel lengths for NMOS and PMOS were on the order of 0.55 and 0.4 µm, respectively. A propagation delay of 106 ps at 5 V was achieved for CMOS ring oscillators fabricated using this process technology.