Dielectric isolation (DI) technology has been available for almost twenty years. It was first developed for low capacitance, high speed circuits, and was later adapted to radiation hardened devices and for high voltage isolation. The authors describe a new method of forming DI structures that simplifies wafer fabrication, reduces the density of process induced defects, and may lead to a more flexible device design. The process is based on recrystallization from the melt of thick Si films deposited over oxidized Si wafers, with a regular array of seeding windows opened in the isolation oxide. The recrystallized films are free of grain boundaries and subboundaries.