The first successful seeded recrystallization of thick, >10 μm Si films deposited on SiO2 is reported. A method of lateral epitaxial growth over oxide (LEGO) has been developed, in which the thick polycrystalline Si films are completely melted by intense photon flux. The epitaxial recrystallization which follows starts at the seeding regions, spaced as far as 1 mm apart, and results in single crystalline Si‐on‐insulator with a low density of defects. The process is carried out in a special furnace with samples placed between a bank of tungsten halogen lamps and a water‐cooled base, allowing uniform and bow‐free crystallization of complete 3‐in. wafers in ∼60 s.