Process for producing polycrystalline semiconductor thin film

The present invention provides a method for producing a polycrystalline semiconductor thin film, comprising: a semiconductor film forming step, forming the non-single-crystal semiconductor thin film having a large heat capacity large heat capacity part and a small heat capacity small heat capacity portion on the substrate; and annealing step, the the non-monocrystalline semiconductor thin film is irradiated to the small heat capacity part is completely melted to the large heat capacity part is not completely melted the energy density of the laser. In the laser annealing step, the laser is a pulsed laser beam is processed into a linear spot having a diameter of the minor and major axes, while the laser beam in the minor axis direction is not larger than the non-single a moving distance of the short axis diameter of the seed crystal semiconductor thin film are sequentially moved while irradiating. Accordingly, it is possible to simply realize a low threshold voltage of the thin film transistor, high carrier mobility and low leakage current characteristics.