The impact of the carrier transport on the random dopant induced drain current variation in the saturation regime of advanced strained-silicon CMOS devices

The variation of saturation drain current (I _d,sat), induced by the random dopant variation (RDF), has been extensively studied by a new multivariate analysis method. It was found that the variation of I _d,sat is originated from V _th,sat and saturation velocity (V _sat), while the variation of V _th,sat comes from the drain induced barrier lowering (DIBL). However, the experimental results shows that V _sat dominates the variation of I _d,sat. From the transport theory, V _sat is further decomposed into V _inj and B _sat, showing that V _inj is the dominant factor of I _d,sat variation. The faster the V _inj is, the less the I _d,sat variation becomes. If one improves the injection velocity, then the variation of I _d,sat can be suppressed. This has been one of the significant benefits of strained silicon technology in CMOS device scaling.