Dopant imaging of power semiconductor device cross sections

Several Scanning Probe Microscopy (SPM) methods allow to image dopant profiles in a range from 10(14) cm(-3) to 10(19) cm(-3) on semiconducting samples. In our work we present Scanning Capacitance Force Microscopy (SCFM) and Kelvin Probe Force Microscopy (KPFM) experiments performed on cross sections of silicon (Si) and silicon carbide (SiC) power devices and epitaxially grown calibration layers. The contact potential difference (CPD) shows under illumination a reduced influence on surface defect states. In addition results from numerical simulation of these microscope methods are discussed. (C) 2016 Elsevier B.V. All rights reserved

Nanoscale characterization of electrical transport at metal/3C-SiC interfaces

In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (ΦB) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis

Использование принципа клиентоориентированности при формировании стратегии развития предприятий

Материалы межвуз. науч. конф. студентов, магистрантов и аспирантов, Гомель, 15 мая 2008 г

Improving the Design of the Shield for the Electric Field in SiC-Based Schottky-Rectifiers and Ion-Implantation Cascades by SPM Dopant-Imaging

In order to avoid a premature breakdown and high leakage-currents of Silicon Carbide (SiC) unipolar Schottky power diodes the Schottky-contact area needs to be shielded from the high electric field inside the device. This can be achieved by the application of a Junction-Barrier Schottky (JBS) device architecture where highly doped p+ regions serve as a shielding structure at the anode side of the device when operated under reverse bias-voltage conditions. In contrast, the active area consumption of this p+-type regions has a negative effect on the differential resistance. To design those p+-shields it is inevitable to compare simulated dopant profiles with those manufactured by ion implantation. Hence, in this contribution we performed SPM-based measurements to image the p+-doped areas. As complementary measurement also secondary electron potential contrast (SEPC) was performed

Development of power semiconductors by quantitative nanoscale dopant imaging

Dopant imaging at high spatial resolution provides an indispensable tool for the improvement of novel power semiconductor devices. Cross-sections of next-generation devices based on Silicon (Si) and Silicon Carbide (SiC) have been investigated by scanning probe microscopy (SPM) derived dopant imaging techniques in a dedicated ultra-high vacuum (UHV) setup to determine the active carrier concentration in differently doped areas of the device under investigation. The physical location of the metallurgical p/n-junction and the associated space-charge regions (SCR) can be experimentally characterized with nanoscale precision. Furthermore, fabrication processes benefit from a reduced number of manufacturing cycles due to the profound knowledge on the evolution of dopant atoms and their corresponding impact on the device performance. Typical power device doping-levels in the range of 1014 cm-3 to 1014 cm-3 can be sensed by the here discussed approach

Experimental evaluation of different passivation layers on the performance of 3kV 4H-SiC BJTs

In this work, the electrical performance in terms of maximum current gain, ON-resistance and blocking capability has been compared for 4H-SiC BJTs passivated with different surface passivation layers. Variation in BJT performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate SiO surface passivation on BJT samples from the same wafer. The highest current gain was obtained for PECVD deposited SiO which was annealed in NO ambient at 1100 °C during 3 hours. Variations in breakdown voltage for different surface passivations were also found, and this is attributed to differences in fixed oxide charge that can affect the optimum dose of the high voltage JTE termination

Effect of the Schottky barrier height on the detection of midgap levels in 4H-SiC by deep level transient spectroscopy

The effect of the Schottky barrier height on the detection of the concentration of midgap defects using deep level transient spectroscopy (DLTS) is experimentally and theoretically studied for EH6 and EH7 defects in 4H-SiC. In this special case, the DLTS signal height for EH6 and EH7 increases with increasing barrier height and saturates at values above 1.5 and 1.7 eV, respectively. Below 1.1 eV, the DLTS peak completely disappears for both defects. The experimental data are explained by a theoretical model. The course of the quasi-Fermi level in the space charge region is calculated as a function of the reverse current through it, which is determined by the barrier height, and the reverse bias applied