THE GETTERING EFFICIENCY OF A DIRECT-BONDED INTERFACE

In these studies the gettering efficiency of copper at a direct bonded interface is compared to the gettering efficiency of a bulk defect zone formed during a one step and three step annealing process of Czochralski silicon wafers. The gettering efficiency of a bulk defect zone is considerably higher than that of the interface. Thus intrinsic gettering is expected to be effective in gettering direct bonded p-n junctions. Without any intrinsic gettering zone, copper silicide readily precipitates at the bonded interface, forming complex star-shaped colonies. Their morphology changes into single colonies in {110} planes if the wafer pairs are prestressed during contacting at room temperature. In this case the gettering efficiency of the bonded interface increases in comparison to the bulk defect zone. Prestressing experiments have shown that the denuded zone width in tensile,stressed regions of a wafer increases.