Optimization of breakdown voltage and substrate current in MOSFETs
|關鍵字:||崩潰電壓;漏電流;場效電晶體;breakdown voltage;substrate current;MOSFET|
With the progress of integrated circuit technology , high-voltage devices with high power have developed into the market of HV-MOSFETs from the market of thyristors and bipolar power transistors ,which have become the most preferable devices to be integrated with the technology of conventional CMOS due to its low cost, fast switching speed, and low power loss. Hence, HV-MOSFETs are mostly-applied to not only control but also carry the high power ICs with high current nowadays. Integrating high power devices with low power circuit is an important in the marketing of electronic application. The Double-Diffusion Drain MOS ( DDDMOS ) is the first device structure proposed to sustain high drain voltage. DDDMOS is still the first choice for devices operating at low voltage due to its simple process. In this thesis, we focus on the impact of ion implantation condition of original process and extra implantation process on the performance of DDDMOS. Using TCAD simulation tools,it is observed that with the increase of implantation energy, the breakdown voltage increases and the snapback issue is relaxed. However, the saturation current will be degraded due to the formation of non-converted p-type region on the drain surface. If the implant dosage is increased, the quasi-saturation phenomenon at high gate voltage, the driving capability, and the turn-off leakage are all improved, but the breakdown voltage would be degraded, and increase substrate current. So we add the extra surface implantation process to improve the substrate current. These results imply that implantation dose and energy might be the better choice.On the basis of TCAD simulation, the implantation energy was raised to 400 KeV and the implantation dose was changed to 6.3×10^12cm-2 and extra surface implantation energy was 50 KeV and the implantation dose was 1.4×10^12cm-2 .A 10% increase of breakdown voltage and 34% reduction of turn-off current were obtained. Meanwhile the 77% reduction of substrate current was observed due to the extra implantation process. It is expected that with higher energy and dose device performance can be improved furthermore.