Upside–Down Annealing of Oxide Thin‐Film Transistors and its Analysis Using Hydrogen‐Diffusion Model

Abstract

Hydrogen plays a crucial role in controlling the electrical characteristics of oxide thin‐film transistors (TFTs). The conductivity of the semiconductor can be modulated by controlling the amount of hydrogen in the active layer. In this study, a thermal annealing of the sample in an inverted orientation (referred to as “upside‐down annealing”) is introduced. The impact of this approach on the hydrogen content within the In2O3 active layer is examined through the lens of a hydrogen diffusion model. By time‐of‐flight secondary ion mass spectrometry analysis, a hydrogen diffusion model for the TFT is established, and it is demonstrated that upside–down annealing is an effective method for preventing hydrogen depletion caused by out‐diffusion. A bottom‐gate bottom‐contact TFT is fabricated to analyze electrical characteristics. By employing different post‐thermal annealing methods on the device, it is discovered that the upside–down annealing enhances the device's performance significantly up to mobility of 22.3 cm2 V−1 s−1, which surpasses more than twice the mobility achieved with the traditionally oriented, “straight” annealed TFT.