Semiconductor device and process for production thereof, and display device

A production method of a semiconductor device comprising:

• a step a of preparing an insulating substrate in which an amorphous semiconductor layer is formed;
• a step b of adding a catalyst element for promoting the crystallization of the amorphous semiconductor to the entire of or a part of the amorphous semiconductor layer;
• a step c of thermally treating the amorphous semiconductor layer at temperatures not lower than 500° C. and not higher than 700° C., and crystallizing the amorphous semiconductor layer in the region to which the catalyst element is added by solid phase crystallization, thereby forming a crystalline semiconductor layer at least partially including a crystalline region;
• a step d of, after the step c, selectively forming a crystallization control layer by the same semiconductor material as that of the amorphous semiconductor layer only on a predetermined region of the crystalline semiconductor layer;
• a step e1 of melt crystallizing only part of the region in which the crystallization control layer is formed in the thickness direction of the crystalline semiconductor layer together with the crystallization control layer, thereby forming a first crystalline semiconductor layer;
• and
• a step e2 of melt crystallizing the region in which the crystallization control layer is not formed of the crystalline semiconductor layer, thereby forming a second crystalline semiconductor layer.