Defect analysis of SOI structures made by CO/sub 2/-laser zone melt recrystallization

Summary form only given. During zone-melting of the polycrystalline silicon layer a large temperature gradient exists between the molten Si layer and the underlying layer which contains already completed devices. The occurrence of defects in the thin monocrystalline layer and in the underlying substrate is closely related to the local temperature rise and to thermal gradients induced by the laser beam in the multilayer system. Therefore, precisely defined laser power and spot size conditions are required. It has been demonstrated that the thin silicon film can be made with a low defect density by using defect entrainment techniques. However, these techniques are not necessarily compatible with a damage free substrate. Substrate damage beneath the insulator has been investigated by preferential etching of angle bevelled cross-sections and by X-ray transmission topography. Another technological problem is wafer bow and warpage following the zone-melt recrystallization process. The conditions for minimizing these effects have been determined.<
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