Analytical Modeling of Short-Channel Effects in BEOL-Compatible Thin-Film Transistors

This article presents a 2-D analytical model for the potential and current characteristics of thin-film transistors (TFTs) using Green’s function approach. The model accurately incorporates the effects of nonuniform trap charge distribution in the channel and includes both top and bottom gate oxide regions with different thicknesses. Solving 2-D Poisson’s equation, we derive closed-form 2-D expressions for the potential profile in the channel. While the model applies to any thin-film technologies such as indium oxide (In2O3), indium gallium zinc oxide (IGZO), graphene, carbon nanotubes (CNTs), etc., in this work, the model is validated using experimental data and TCAD Sentaurus simulations for In2O3 TFTs. Key results include analysis of short-channel effects (SCEs), gate oxide scaling, and channel thickness variations on device performance. The model successfully predicts subthreshold characteristics and drain-induced barrier-lowering (DIBL) while identifying the limitations in the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> current region due to the absence of various scattering phenomena, such as surface scattering in the analytical formulation. An improved mobility model, accounting for field dependence, enhances the accuracy in the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> region, ensuring agreement with experimental and TCAD data across various bias conditions.