A simple fabrication process of T-shaped gates using a deep-UV/electron-beam/deep-UV tri-layer resist system and electron-beam lithography

A new fabrication process of T-shaped gates has been developed using a deep-UV/electron-beam/deep-UV (DUV/EB/DUV) tri-layer resist system and electron-beam lithography for the first time. The simple process accomplished a submicron T-shaped gate by a single exposure and a single development step. The narrow/wide/narrow opening of the DUV/EB/DUV resist structure can be accurately controlled by the e-beam dosage and the development conditions. Differences in the sensitivities of the DUV resist and the EB resist were investigated. Due to the lower sensitivity of the adopted DUV resist to the electron beam, the smaller opening of the DUV resist layer was obtained. The higher sensitivity of the EB resist resulted in a wider opening in the middle resist layer. A 0.15-mu m-gate-length T-shaped gate can be easily formed by the short-process-time and low-production-cost hybrid DUV/EB/DUV resist approach.