Progress in laser annealing for low-temperature semiconductor processing and its application to advanced electronics and display devices

The development of polycrystalline-silicon-thin-film transistors (poly-Si TFTs) using the laser crystallization method is reviewed. Pulsed laser crystallization has an advantage of rapid crystallization of silicon films at a low processing temperature. Structural and electrical properties of laser crystallized silicon is discussed. Small crystalline grains with high carrier mobility are formed by laser irradiation. However, a high density of defects ∼10¹⁸ cm⁻³ exists at grain boundaries in laser crystallized silicon films. Oxygen plasma and H₂O vapor heat treatments effectively reduce the density of defect states. These methods result in poly-Si TFTs with a carrier mobility of 830 cm²/Vs and a threshold voltage of 1.5 V.