Nanovoid layer induced by He+ and H+ implantation and its gettering effect in SOI wafers

Physical phenomena such as blistering and flaking of silicon under high dose H⁺ ion implantation have successfully been applied to the Smart-cut SOI process. In this study, a novel gettering method using nanovoids induced by H⁺ or He⁺ implantation has been studied to remove Cu and Ni impurities from the top Si layer of SOI wafers. He⁺ and H⁺ ions were implanted into the substrates of SIMOX (separation by implantation of oxygen) wafers to form a layer of nanocavities beneath the BOX layer. The gettering of Cu and Ni impurities, which were implanted into the top Si layer, to the voids has been studied by SIMS (secondary ion mass spectroscopy). XTEM (cross-sectional transmission electron microscopy) was employed to investigate the microstructure of the He⁺ and H⁺ implantation-induced voids in silicon. The results indicate that the voids induced by He⁺ and H⁺ implantation are strong gettering centers for Cu and Ni in SIMOX wafers. He⁺ ion implantation is found to be more suitable for void layer formation and gettering than H⁺ implantation