A semiconductor device having a display unit, which is small in size, suppresses the defect caused by the mounting of IC chips and the like on the substrate, and operates at a high speed. A semiconductor display unit and other circuit blocks are integrally formed on the substrate having an insulating surface by using a process for fabricating TFTs that realize a high degree of mobility. Concretely, there is employed a process for crystallizing a semiconductor active layer by using a continuously oscillating laser. Further, the process for crystallization relying upon the continuously oscillating laser is selectively effected for only those circuit blocks that must be operated at high speeds, thereby to realize a high production efficiency.