JPS6446968A - Polycrystalline silicon thin film transistor and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a polycrystalline silicon thin film transistor with high mutual conductance, by making the density of captured electrons existing in the crystal grain boundary in a channel region equal to or smaller than a specific value. CONSTITUTION:By using a polycrystalline silicon thin film formed by fusing recrystallizing method such as a laser recrystallizing method, the captured electron density in the crystal grain boundary in the channel region of a polycrystalline silicon thin film transistor is decreased to a value less than or equal to 8X10<11>cm<-2>. Therefore, in the state where the electric field intensity in the vertical direction to a gate oxide film and a semiconductor boundary surface is less than or equal to 2X10<5>V/cm, the same transition to the carrier conveying mechanism as the case of a single crystal is enabled. Thereby, even in the case of polycrystalline state, the field-effect mobility of the nearly same degree as single crystal is realized, and a polycrystalline silicon thin film transistor with high mutual conductance can be obtained.