Scaling study of contact operation at constant current in self-aligned top-gated oxide semiconductor field-effect transistors

An extraction framework that can precisely reflect the metal-semiconductor contact behavior is developed for self-aligned top-gated oxide semiconductor field-effect transistors (SA-TG OS FETs). In contrast to the conventional transfer length method, where the extraction is performed at a constant drain voltage condition, an improved constant current scheme, resilient to bias-dependent series resistance, is employed to enhance the extraction accuracy. This technique enables one to unveil the underlying device physics at the metal-OS interface under top-gated operation. Furthermore, the resistance of contact and extension regions can be accurately differentiated by exploiting the extraction results from the three-terminal FETs and two-terminal resistors using the present framework. Moreover, the significant role of the specific contact resistivity at the metal-OS interface is highlighted as the dominating factor that detrimentally affects the electrical performance of OS FETs.