JPS647610A - Forming method for soi structure - Google Patents

Abstract

PURPOSE:To facilitate recrystallization of a thin semiconductor film irrespective of the thickness of the film by enhancing a laser beam reflectivity on a boundary between the film and an insulating layer by employing a multilayer film made of a plurality of types of insulating films as the insulating layer. CONSTITUTION:A thin semiconductor film 5 insulated by insulating layers 2-4 from a semiconductor substrate 1 is irradiated with laser beam 6, then heated to be melted, and recrystallized. In such a case, a multilayer film made of a plurality of insulating films is used as the layers 2-4, and a laser beam reflectivity is enhanced on a boundary between the film 5 and the layers 2-4. For example, a silicon oxide film 2, a silicon nitride film 3 and a silicon oxide film 4 are sequentially formed 0.27, 0.04 and 0.1mum thick on the substrate 1 as an interlayer insulating film. A thin polysilicon film 5 is formed 0.5mum thick thereon. Thus, the thin semiconductor film can be melted and recrystallized with smaller amount of laser beam. For example, when the semiconductor film becomes thinner, the semiconductor film can be melted and recrystallized.