Specific contact resistivity reduction in amorphous IGZO thin-film transistors through a TiN/IGTO heterogeneous interlayer
Joo Hee Jeong, Seung Wan Seo, Dongseon Kim, Seong Hun Yoon, Seung Hee Lee, Bong Jin Kuh, Taikyu Kim, Jae Kyeong Jeong, Jae Kyeong Jeong, Jae Kyeong Jeong
Abstract
Abstract Oxide semiconductors have gained significant attention in electronic device industry due to their high potential for emerging thin-film transistor (TFT) applications. However, electrical contact properties such as specific contact resistivity ( ρ C ) and width-normalized contact resistance ( R C W ) are significantly inferior in oxide TFTs compared to conventional silicon metal oxide semiconductor field-effect transistors. In this study, a multi-stack interlayer (IL) consisting of titanium nitride (TiN) and indium-gallium-tin-oxide (IGTO) is inserted between source/drain electrodes and amorphous indium-gallium-zinc-oxide (IGZO). The TiN is introduced to increase conductivity of the underlying layer, while IGTO acts as an n + -layer. Our findings reveal IGTO thickness ( t IGTO )-dependent electrical contact properties of IGZO TFT, where ρ C and R C W decrease as t IGTO increases to 8 nm. However, at t IGTO > 8 nm, they increase mainly due to IGTO crystallization-induced contact interface aggravation. Consequently, the IGZO TFTs with a TiN/IGTO (3/8 nm) IL reveal the lowest ρ C and R C W of 9.0 × 10 −6 Ω·cm 2 and 0.7 Ω·cm, significantly lower than 8.0 × 10 −4 Ω·cm 2 and 6.9 Ω·cm in the TFTs without the IL, respectively. This improved electrical contact properties increases field-effect mobility from 39.9 to 45.0 cm 2 /Vs. This study demonstrates the effectiveness of this multi-stack IL approach in oxide TFTs.