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.

Thermal Dehydrogenation Impact on Positive Bias Stability of Amorphous InSnZnO Thin-Film Transistors

“…According to Young’s equation, the reduction in the contact angle indicates an increase in the surface energy of the a-ITZO films, resulting in hydrophilic surface states. , This suggests that as thermal dehydrogenation progresses, hydrogen-related bonding groups can be formed near the surface of the ITZO films, leading to an increase in surface energy . Therefore, our XPS and contact angle results quantitatively demonstrated that excess hydrogen within the a-ITZO film can be desorbed as H 2 O and H 2 molecules by combining with oxygen present in the film surface and air, potentially causing out-diffusion of hydrogen. , …”