Patent ID: 8722521

Claim:
A method of manufacturing an active matrix display device comprising: forming a semiconductor film over a substrate; emitting a laser beam having a first cross section perpendicular to a propagation direction of the laser beam; expanding the laser beam along a first direction to increase the cross section of the laser beam along the first direction; regulating an optical path length of the expanded laser beam along the first direction using a concave lens; condensing the laser beam along a second direction orthogonal to the first direction; and increasing crystallinity of the semiconductor film by scanning the semiconductor film with the laser beam along a third direction orthogonal to the first direction wherein the laser beam has a second cross section on a surface of the semiconductor film, the second cross section being larger than the first cross section along the first direction and shorter than the first direction along the third direction; after increasing the crystallinity, patterning the semiconductor film into a plurality of semiconductor layers, each including a region to become a channel forming region of a thin film transistor; forming an insulating layer over the plurality of semiconductor layers; and forming a plurality of pixel electrodes over the insulating layer.