PURPOSE: To obtain an IC which performs high speed action by using a substrate whereon island single crystals with bottom and side surfaces surrounded by insulators are selectively formed.

CONSTITUTION: Apertures are selectively opened through an SiO2 film 6 on a single crystal Si substrate 1 containing high density B in the surface and filled with the single crystal Si 15, and an SiO2 film 12 is superposed. An Si substrate 14 provided with an SiO2 film 13 on the surface is prepared separately, and then the films 13 and 12 are adhered 11 with the solution wherein glass fine powder with B2O3, PbO, and SiO2 as the main constituents is dissolved in solvent together with ethyl cellulose. Next, only the substrate 1 is removed by lapping and etching utilizing the difference of impurity densities. In forming the single crystal Si 15, it can be grown selectively only on the Si substrate under the condition of HCl 0.6l/min to 50torr, 1,000°C, SiH2Cl2 300cc/min. This constitution enables to form a single crystal Si of a desired size and high quality uniformly on an insulator by reducing isolated element regions down to 1μm or less, and accordingly an IC of high speed action can be obtained.