| 摘要 |
PROBLEM TO BE SOLVED: To facilitate the designing of an electric device formed on a semiconductor layer of a front surface in forming a thick portion, e.g. an optical waveguide on the semiconductor layer sandwiched by a double-layer insulator. SOLUTION: A dual SOI substrate 10 has a silicon layer 15, an insulation film (silicon oxide film) 14, a silicon layer 13 and an insulation film 12 in this order from the front surface side. The depth distribution of the upper insulation film 14 is made to be uniform and the depth distribution of the lower insulation film 12 is made not to be uniform, and a thick portion along a predetermined passage is formed on the silicon layer 13. The refractive index of Si is 3.5 and the refractive index of SiO<SB>2</SB>is 1.5. The thick portion of the silicon layer 13 is used a core and the insulation films 12, 14 corresponding to the thick portion are used as clads, and the optical waveguide 16 along the predetermined passage is formed. In this way, since the thickness of the silicon layer 15 on the front surface side is uniform and characteristics of MOS devices formed on each portion of the silicon layer 13 can be matched easily, and the designing of the electric device is facilitated as a whole. COPYRIGHT: (C)2007,JPO&INPIT |
