A Novel Photoresist-Based Film-Profile Engineering Scheme for Fabricating Double-Gated, Recess-Channel IGZO Thin-Film Transistors

We reported an experimental fabrication of double-gated (DG) thin-film transistor (TFT) with IGZO recess-channel using a designer photoresist-based thin-film profile engineering approach. In this approach, an organic shadow mask of photoresist (PR) was formed over a p(+)-Si wafer that was encapsulated by an oxide layer, The lithographically-patterned PR layer is an effective mask for shadowing reactive species during the subsequent deposition steps of IGZO and Aluminum, enabling the formation of IGZO recess-channel and discrete Al source/drain pads at room temperature. The top-gate or DG configurations with the Si substrate serving as the bottom-gate were investigated. The fabricated DG TFTs show significant; improvements in both I-ON and I-OFF as compared with single-gated TFTs. The proposed process scheme is readily applicable to the back-end-of-line of a chip. This work demonstrates the feasibility of IGZO recess-channel TFTs in various gated configurations, enabling a building block for emerging functional devices for More-than-Moore applications. (C) 2020 The Japan Society of Applied Physics