Superjunction (SJ) MOSFETs with low on-resistance and high sustain voltage are widely used as main switching power devices. For the p/n-pillars of SJ-power devices, precise doping at low-doping region below 1016 cm- 3 concentrations is required, and thus high-sensitivity 2D-carrier profiling of the pillars is indispensable where conventional SCM is insufficient. Previously, we developed the high-vacuum SSRM enabling high-spatial resolution and site-specific 2D-carrier profiling. In this study, we investigated comprehensively the feasibility of applying SSRM to SJ-power devices at low doping below 1016 cm- 3, with both SJ-diodes and low-doping references. The bias dependence of SSRM was analyzed on SJ-diodes and was compared with T-CAD simulations, and both the p- and the n-pillars demonstrate Schottky-like behavior between the probe and the sample. Consequently, the pn-junction delineation also moved with applied bias. We also performed SSRM on reference-staircase structures with low-doping layers down to 1014 cm- 3 of p, n and p/n types, and comparison with SIMS and SRP confirmed the high sensitivity of SSRM. The Schottky contact of the probe-sample was found to be pronounced at low-doping region, particularly p-type doped region. Therefore, the bias polarity should be taken into account to obtain correct information at the low-doping region.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Safety, Risk, Reliability and Quality
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering