High-Performance Solid-Phase Crystallized Polycrystalline Silicon Thin-Film Transistors with Floating-Channel Structure

Abstract

High-performance solid-phase crystallized polycrystalline silicon thin-film transistors with a floating-channel active region (FC poly-Si TFTs) are proposed in this study. A high-quality poly-Si channel film accompanied by a larger grain size and fewer microstructural defects could be obtained. Compared with the conventional poly-Si TFTs (CN poly-Si TFTs), the fabricated FC poly-Si TFTs exhibit superior electrical characteristics, including lower threshold voltage, higher field-effect mobility, and lower trap state density. These electrical performance improvements could be attributed to the fact that the α-Si film with a floating-channel structure can relieve the stress generated from the crystallization process accompanying the trap state density reduction and grain size enhancement. In addition, the FC poly-Si TFTs also exhibit improved hot-carrier stress immunity due to the reduced weak Si–H bonds from fewer grain boundaries in the poly-Si channel. Therefore, the proposed FC poly-Si TFTs can be easily fabricated by conventional solid-phase crystallization, and suitable for future high-performance flat-panel display applications.