Low-temperature and low thermal budget fabrication ofpolycrystalline silicon thin-film transistors

A top-gate self-aligned n-channel polycrystalline silicon (poly-Si) thin-film transistor (TFT) has been fabricated with low temperature (⩽550°C) and low thermal budget process. The ultrahigh vacuum chemical vapor deposition (UHV/CVD) grown poly-Si was served as the channel film, the chemical mechanical polishing (CMP) technique was used to polish the channel surface, plasma-enhanced chemical vapor deposited (PECVD) tetraethylorthosilicate (TEOS) oxide was used as the gate dielectric, and NH₃ plasma was used to passive the device. In this process, the solid phase crystallization (SPC) step is not needed. A field effect mobility of 46 cm²/V-s, ON/OFF current ratio of over 10⁷, and threshold voltage of 0.8 V are obtained. The significant reduction in process temperature and thermal budget make this process advantageous for larger-area-display peripheral driver circuits on glass substrate