Patent ID: 7888247

Claim:
A method of forming a polycrystalline semiconductor film, comprising: irradiating an amorphous semiconductor film formed on an insulating substrate with light to convert the amorphous semiconductor into a laterally grown polycrystalline semiconductor to form a polycrystalline semiconductor film, wherein the irradiating step comprises controlling crystal growth in the amorphous semiconductor such that, on an X-axis and a Y-axis which are set with respect to a surface of the amorphous semiconductor film and which are orthogonal to each other, first crystal grains laterally grow in a first direction along the X-axis from a first group of initial nuclei on a first straight line extending along the Y-axis, second crystal grains laterally grow in a second direction opposite to the first direction along the X-axis from a second group of initial nuclei arranged on a second straight line extending along the Y-axis, apart from the first group of initial nuclei along the X-axis and the first straight line, the first crystal grains collide against the second crystal grains at different points in time along the Y-axis, and growing speeds of the first crystal grains and the second crystal grains vary between predetermined points along the Y-axis.