Optimize The Structure Of A BCD Compatible LDMOS By TCAD Tools

Use the computer aided design tools to serve the IC produce, design and study is becoming a more and more important way in IC industry of nowadays. The author of this paper use the Silvaco TCAD tools to study how to improve the breakdown voltage of a LDMOS structure which compatible with BCD process. The author has used the process simulator tool to simulate the IC produce process, the device simulate tool to test the breakdown voltage, and the plot tool to study the impact to the breakdown voltage.This paper has achieved the target of 1200V+ breakdown voltage of a LDMOS which has a 75 micronmeter wide drift region and uniform P layer, by the support of TCAD tools and latest LDMOS theory about how to improve the breakdown voltage. The major part of this paper is the discussions of how the Resurf (Reduced Surface Field) theory and double Resurf theory worked, and study the factor of epi doping, epi thickness, Ptop structure, and the gate field plate change impact to the breakdown voltage, and all these changes will not change the compatible of the reference LDMOS structure to original BCD process.The whole process and script of process simulation and device simulation of LDMOS has been shown in this paper.