Fabrication of Novel Three-Step Drift-Doped Low-Temperature Polycrystalline Silicon Lateral Double-Diffusion Metal-Oxide-Semiconductor Using Excimer Laser Crystallization

Abstract

Low-temperature polycrystalline silicon (poly-Si) thin-film transistor lateral double-diffusion metal-oxide-semiconductor field-effect transistors (LTPS TFT LDMOSFETs) and lateral insulated-gate bipolar transistors (LIGBTs) were fabricated by combining a thin-film transistor with a power structure, three-step drift doping, and excimer laser annealing. The maximum breakdown voltage of the three-step drift-doped LTPS-LDMOS after excimer laser annealing is 286 V with a 35 mu m drift region length (L(drift)). The specific on-resistance is low (approximately 9 Omega cm(2)) and the ON/OFF current ratio is about 1.28 x 10(6) with L(drift) = 15 mu m. The subthreshold swing (SS) is about 1 V/decade. Comparing the three-step drift-doped LDMOS with the three-step drift-doped LIGBT under the same processing conditions clearly indicates that the breakdown voltage and current capacity of LIGBT exceeds those of LDMOS. (C) 2009 The Japan Society of Applied Physics