The fabrication procedure of the SOI/SOI/bulk-Si triplelevel structure is developed by using the improved selective laser recrystallization technique and MOS LSI technology. The enlarged crystal stripes sandwiched by straight grain boundaries are produced on the planarized insulating film which overlies the device structure in bulkSi, and also SOUbulk-Si double-layered structure. The basic characteristics of MOSFET's in a triple-level structure are evaluated.