PURPOSE: To obtain, with good reproducibility, a semiconductor thin film whose electric characteristic is good and which has been crystallized reliably by a method wherein the distribution of an irradiation laser energy density is set to be stepwise and specific in a stepwise scanning direction.
CONSTITUTION: A semiconductor thin film is formed on a substrate 11 ; the thin film 1 is irradiated with a pulse laser 2; and the thin film 1 is crystallized by a melting method. When the thin film 1 is irradiated with the laser 2, e.g. a zigzag scanning operation is executed by a scanning operation in the x- direction and a stepwise scanning operation in the y-direction. The energy density of a beam spot S regarding individual beam spots b1 to b5 is increased gradually in the x-direction from the front of the x-direction toward the central part when individual transmission distributions of filters F1 to F5 are selected properly. Thereby, a stepwise or mountain-shaped distribution in which the energy density is lowered gradually toward the rear is obtained. Thereby, when a volatile substance exists in the thin film 1, the thin film is crystallized so as to be a more excellent film quality because its sudden volatilization can be changed to a gentle volatilization.
HARA MASATERU
SANO NAOKI
USUI SETSUO
