Normally‐Off Top‐Gate Self‐Aligned Field‐Effect Transistor Including Crystal InOx Formed by Hydrogen Gas‐Free Sputtering With Channel Length of 3 μm and High Field‐Effect Mobility Over 75 cm 2 /Vs Fabricated through 400°C Process

ABSTRACT We fabricated a top‐gate self‐aligned field‐effect transistor incorporating a Crystal InO x (crystal IO) active layer formed by hydrogen gas‐free sputtering. By employing a new process in which hydrogen is supplied from an underlying SiON film formed by plasma‐enhanced chemical vapor deposition, the transistor exhibits normally off characteristics with a short channel length of 3 μm and a high field‐effect mobility over 75 cm 2 /Vs. A crystal IO backplane with field‐effect mobility comparable to that of a low‐temperature polysilicon backplane can be obtained without capital investment in a hydrogen gas line, enabling application to existing production lines.