This technology is a method for laser processing amorphous silicon into polycrystalline silicon which is capable of generating large grains with specified orientations.
Thin-film silicon is an indispensable material for the fabrication of flat-panel displays and thin-film transistors. In order to engineer the best performance, the grain structure and orientation of the silicon must be precisely controlled. Laser processing, currently the preferred method, allows amorphous silicon to be transformed into crystalline silicon. However, this method is time consuming and often results in small grains with random orientations. Therefore, a method to precisely control the crystallization process of amorphous silicon is sorely needed.
This technology is a method to control the crystallization of amorphous silicon using laser modulation. First, a sequence of excimer laser pulses is homogenized in a predetermined plane. The laser pulses are then masked with a two-dimensional array to generate patterned beamlets, which are incident upon amorphous silicon to induce specific crystal morphologies. Various patterns of beamlets can be obtained, such as parallel or intersecting slits, saw-tooth, and dot-type arrays, with each pattern having different effects on the crystallinity. Uniformly-sized large grains can thus be obtained, while maintaining precise control over their orientations.
The technology has been implemented as part of the sequential lateral solidification process.