Air-gap polycrystalline silicon thin-film transistors for fully integrated sensors

Abstract

Air gap thin-film transistors (TFTs) were fabricated using a solid phase crystallization process. Undoped polycrystalline silicon (polysilicon) was used as the active layer and a highly doped polysilicon bridge was used as the gate, which promotes the air gap. These TFTs have comparable threshold voltage (VT) and subthreshold slope characteristics to TFTs fabricated using pulsed laser crystallization, and using silicon dioxide as gate insulator. The low value of VT is very important for low power consumption. Moreover, the air-gap TFT fabrication process is compatible with low-temperature glass substrate technology, which allows the integration of sensors and electronics circuits.