Patent ID: 7790533

Claim:
A manufacturing method for a semiconductor device comprising: emitting a first laser beam from a first laser oscillator; emitting a second laser beam from a second laser oscillator; passing the first laser beam through a dichroic mirror and reflecting the second laser beam at the dichroic mirror so that the first laser beam and the second laser beam have a same optical axis; passing the first laser beam and the second laser beam having the same optical axis through a cylindrical achromatic lens so that the first laser beam and the second laser beam have a same beam length on a surface of a semiconductor film; crystallizing the semiconductor film by irradiating the semiconductor film with the first laser beam and the second laser beam having the same optical axis and the same beam length, wherein wavelength of the first laser beam is different from that of the second laser beam, and wherein a focal point of the first laser beam is different from that of the second laser beam.