Dopant profile extraction by inverse modeling of scanning capacitance microscopy using peak dC/dV

Abstract

Scanning capacitance microscopy (SCM) has proven to be successful for junction delineation. However quantitative dopant profile extraction by SCM still remains a difficult challenge, due to limited understanding of relevant physics especially at p-n junction, as well as difficulties to accurately quantify all parameters in modeling. In this paper we present a new procedure, the use of peak dC/dV at every spatial point, for dopant profile extraction. The advantage of such a technique is twofold. First it eliminates problems encountered using a fixed dc bias such as contrast reversal. Second, it also excludes the need to model interface traps. This is because the peak dC/dV value is independent of the presence of interface traps, as demonstrated in our experimental results. Furthermore, based on our understanding of the influence of mobility degradation at p-n junction, we propose that low surface mobility model should be used in simulation so that only the accumulation-to-depletion dC/dV is extracted.