Changing structure of semiconductor layer e.g. amorphous silicon layer, by irradiating area of semiconductor layer with laser light generated from laser beam, and splitting laser beam into beam parts with different radiation intensities

摘要

The method for changing a structure of a semiconductor layer such as an amorphous silicon layer (30), comprises irradiating an area of the semiconductor layer with a first laser light and then with a second laser light, where the first and second laser lights are generated from a laser beam (21), splitting the laser beam into two laser beam parts with different radiation intensities, focusing the two laser beam parts to the first and second laser light, paralleling the first and second laser lights to each other, and changing the distribution of the radiation intensities of the beam parts. The method for changing a structure of a semiconductor layer such as an amorphous silicon layer (30), comprises irradiating an area of the semiconductor layer with a first laser light and then with a second laser light, where the first and second laser lights are generated from a laser beam (21), splitting the laser beam into two laser beam parts with different radiation intensities, focusing the two laser beam parts to the first and second laser light, paralleling the first and second laser lights to each other, changing the distribution of the radiation intensities of the both laser beam parts during splitting the laser light, and changing a direction, in which the first and second laser lights cover an area of the semiconductor layer. The irradiation with the second laser light temporally takes place after the radiation with the first laser light. The first laser light has a less radiation intensity than the second laser light. The amorphous silicon layer is partially changed into polycrystalline silicon. The first and second laser lights cover the area of the semiconductor layer one after the other in a direction, and irradiate the area to each other with a predetermined temporal and/or spatial distance. The time period between the first and second laser lights is 1-5 ms. The first laser light irradiates the semiconductor layer with the radiation intensity, with which the semiconductor layer is not destroyed. The first laser light irradiates the amorphous silicon layer with the radiation intensity, with which the amorphous silicon layer is partially changed into polycrystalline silicon. The amorphous silicon layer has a thickness of larger than 10 nm to 10 mu m. The ratio of the radiation intensity of the first laser beam to the radiation intensity of the second laser beam is 0.25 to 0.45. The first and/or the second laser light have a wavelength of 515 nm or 532 nm, and a repetition frequency of 10-250 kHz. The geometrical half-width of the first and/or the second laser light is 5-6 mu m. The first and/or the second laser light are a laser beam formed in a line or a focused laser spot. An independent claim is included for a device for irradiating a semiconductor layer.