Defect Generation in Device Processing and Impact on the Electrical Performances

This paper collects the results of some experiments aimed at investigating the physical mechanisms of defect generation in devices. It is shown that suitable limits for the mechanical stress can be defined to prevent defect generation. In addition, a high temperature stress release annealing can be beneficial for stress reduction and defect prevention. The annealing of implanted layers may result in crystal defect formation even with no contribution from mechanical stress. In this case, the silicon surface plays a relevant role in reducing the point defect concentration and hence the nucleation of extended defects. In the annealing process of high energy implantations, the most damaged region is far from the wafer surface. Under these conditions, impurities in the silicon substrate play a relevant role in determining the resulting defect morphology. The presence of interstitial oxygen forces defects to grow along <110> directions parallel to the silicon surface, thus preventing them to reach the device region.