Influence of process-induced stress on device characteristics and its impact on scaled device performance

Abstract

This paper reports on the effects of oxidation-induced stress on the generation current in pn-junction and gated diodes. It is observed that even in the regime where no extended defects are present, the generation current is a strong function of the compressive stress in the substrate. Experimental results are presented revealing an order of magnitude increase in generation current for stress changes of a few 100 MPa's. A stress-induced bandgap narrowing model that describes the relationship between the oxidation-induced stress and the generation current in MOS devices is proposed and experimentally verified. Using this model, we have calculated the stress-induced generation current in scaled shallow trench isolated (STI) devices due to reoxidation after STI formation. As the device pitch is reduced a large increase in stress and leakage current is observed, consistent with the experimental data.