Deeper insight into lifetime-engineering in 4H-SiC by ion implantation

Abstract

Lifetime-engineering in 4H-SiC is important to obtain a low forward voltage drop in bipolar devices with high blocking voltages above 10 kV. It is known that the implantation of carbon and subsequent thermal annealing can be used to improve the minority carrier lifetime of as-grown epitaxial layers due to annihilation of carbon vacancies and, therefore, reduce the lifetime limiting defect Z1/2. In this paper, the ion implantation of other ions (N, Al, B, and As) besides carbon and their impact on minority carrier lifetime and point defect concentration are shown. Special attention is paid to the effect of ion implantation with subsequent electrical activation by high temperature annealing. A strong influence of the implantation dose and, therefore, corresponding resulting doping concentration was found. A lifetime enhancement could be found for some implanted species for higher implantation doses whereas the detrimental effect of high temperature annealing dominated at low implantation doses. The results reveal that the implantation dose and the occupied lattice sites are important parameters to achieve a lifetime enhancement. A model is presented which explains the different impacts of various implanted ions and a more detailed understanding of lifetime-engineering by ion implantation. With this knowledge, it was possible to reduce the detrimental Z1/2 defect in a large part of thick epitaxial layers with conventional shallow ion implantation and high temperature annealing. Consequently, the minority carrier lifetimes of the epitaxial layers could be enhanced.

Effects of ion implantation process on defect distribution in SiC SJ-MOSFET

“…Additionally, the structures and concentrations of the defects are dependent on the implantation temperature and implanted ion species. [12][13][14] Therefore, it is important to understand the effects of defects generated by the implantation for the optimum design of SiC SJ-MOSFET.…”

Depth Distribution of Defects in SiC PiN Diodes Formed Using Ion Implantation or Epitaxial Growth

“…To date, there have been several reports on the defects induced by Al‐ion implantation using deep‐level transient spectroscopy (DLTS) and cathodoluminescence (CL). [ 19–25 ] The Al‐induced defects observed by DLTS were on the order of 10 13 cm −3 within a depth of ≈2 μm from the implanted regions. [ 19–22 ] CL studies have observed a distribution to ≈10 μm from the implanted region.…”

“…[ 19–25 ] The Al‐induced defects observed by DLTS were on the order of 10 13 cm −3 within a depth of ≈2 μm from the implanted regions. [ 19–22 ] CL studies have observed a distribution to ≈10 μm from the implanted region. [ 23,24 ] However, even defects with concentrations of 10 12 cm −3 reduce the carrier lifetimes, [ 4 ] and the presence of defects in the drift layer is critical for a conductivity modulation.…”

Cross‐Sectional Carrier Lifetime Profiling and Deep Level Monitoring in Silicon Carbide Films Exhibiting Variable Carbon Vacancy Concentrations

“…[ 9 ] It should be mentioned in this regard that carrier lifetime control in such optically thick epilayers has already gained considerable attention worldwide. [ 10–18 ]…”

“…[9] It should be mentioned in this regard that carrier lifetime control in such optically thick epilayers has already gained considerable attention worldwide. [10][11][12][13][14][15][16][17][18] Accordingly, the material of choice for the thermal generation and C-injection experiments should preferably involve ultra-thick and low-doped epilayers to ensure a broader profiling range and depth discrimination.…”