Polycrystalline silicon layer transfer by ion-cut

Abstract

Ion-cut polycrystalline silicon (polysilicon) layer transfer by thermal separation was demonstrated after observing hydrogen-induced surface blistering and direct bonding of a chemomechanically polished surface. After hydrogen implantation into a chemical-vapor deposited polysilicon wafer (the donor wafer), the wafer surface was polished for wafer bonding. The hydrogen-implanted and polished wafer was then bonded to a thermally oxidized silicon wafer (the handle wafer) by low-temperature wafer direct bonding. The bonded pair was then heated until hydrogen-induced silicon layer cleavage occurred along the hydrogen-implanted layer, resulting in the transfer of the polysilicon layer to the handle substrate. The transferred polysilicon surface had the same roughness as ion-cut single-crystal silicon layers. The layer transfer time of polysilicon was significantly reduced from that of single-crystal silicon, and had an activation energy nearly ten times lower than that of its single-crystal counterpart.