Semiconductor thin film forming method and semiconductor device

Abstract

A polycrystal thin film forming method comprising the step of forming a semiconductor thin film on a substrate 14 , and the step of flowing a heated gas to the semiconductor thin film while an energy beam 38 is being applied to the semiconductor thin film at a region to which the gas is being applied to thereby melt the semiconductor film, and crystallizing the semiconductor thin film in its solidification. The energy beam is applied while the high-temperature gas is being flowed, whereby the melted semiconductor thin film can have low solidification rate, whereby the polycrystal thin film can have large crystal grain diameters and can have good quality of little defects in crystal grains and little twins.

1 . A semiconductor thin film including a width-reduced part, at least the width-reduced part having a quasi-monocrystal state, which is a crystal state including grain boundaries having an inclination angles of not more than 90° to a current direction.