Patent ID: 8421080
Filing Date: 2013-04-16
Classification: H01L

Abstract:
1. A thin-film transistor array device comprising: a substrate; a first gate electrode provided above said substrate; a second gate electrode provided above said substrate and in parallel with said first gate electrode; a gate insulating film provided on said first gate electrode and second gate electrode; a first crystalline semiconductor film provided on said gate insulating film and above said first gate electrode, said first crystalline semiconductor film being made of silicon and including crystal grains having a first average grain size; a first source electrode and a first drain electrode which are formed above said first crystalline semiconductor film; a second crystalline semiconductor film provided on said gate insulating film and above said second gate electrode, said second crystalline semiconductor film being made of silicon and including crystal grains having a second average grain size which is smaller than the first average grain size; and a second source electrode and a second drain electrode which are formed above said second crystalline semiconductor film, wherein the crystal grains of said first crystalline semiconductor film are formed by: a first process of irradiating, with a continuous wave laser, a noncrystalline semiconductor film made of silicon such that a temperature of the noncrystalline semiconductor film is within a temperature range of 600° C. to 1100° C., the continuous wave laser having a continuous light intensity distribution that is convex upward in each of long and short axes; a second process of crystallizing the noncrystalline semiconductor film according to the temperature range of 600° C. to 1100° C.; and a third process of increasing a grain size of the crystal grains of the noncrystalline semiconductor film that becomes crystallized according to a temperature range of 1100° C. to 1414° C., when the temperature of the noncrystalline semiconductor film increases from 1100° C. to 1414° C. due to latent heat which is generated when the noncrystalline semiconductor film becomes crystallized by the laser irradiation, the continuous light intensity distribution that is convex upward in the long axis is predetermined such that a portion in which the temperature of the noncrystalline semiconductor film increases from 1100° C. to 1414° C. due to the latent heat has a constant width, in the third process, the crystal grains of said first crystalline semiconductor film are further formed using an inner region having the constant width, the inner region being included in the continuous light intensity distribution that is convex upward in the long axis and is predetermined as having the constant width, the crystal grains of said second crystalline semiconductor film are formed according to the same processing as in the first and second processes, using the laser irradiation performed in the first and second processes, and the crystal grains of said second crystalline semiconductor film are further formed using an outer region which is located outside the inner region having the constant width, the outer region being included in the continuous light intensity distribution that is convex upward in the long axis and is predetermined as having the constant width.