100-nm IGZO Thin-Film Transistors With Film Profile Engineering

100-nm indium-gallium-zinc-oxide (IGZO) thin-film transistors were fabricated with a one-mask process, which takes the advantage of photoresist trimming technique and the concept of film profile engineering (FPE). With I-line-based photolithography, a device with channel length of 97 nm has been successfully fabricated. The FPE device contains a conformal Al₂O₃ gate oxide, concave IGZO channel, and discrete source/drain (S/D) Al contacts. Good device characteristics including a high-ON/OFF current ratio (>10⁷) and good subthreshold swing (140 mV/decade) are obtained. Nonetheless, high-S/D series resistance presents a key issue that needs to be addressed for further device performance improvement.