| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a parasitic bipolar transistor which has low breakdown voltage, by having a process of forming first and second conduction type of well regions, a process of forming a first conduction type of first impurity region, and others. SOLUTION: A p-type epitaxial layer doped with about 5×10<15> cm<-3> of boron by CVD method is made in a thickness of about 2-5μm on a p-type silicon substrate 1 where boron is diffused in concentration of 1×10<19> cm<-3> or over. Next, boron ions are implanted, under the condition of about 10keV, 1×10<13> cm<-2> , using a photoresist as a mask, into this p-type epitaxial layer. Moreover, with photoresist 20 and 220 as masks, phosphorous ions are implanted under a condition of about 100keV, 1×10<13> cm<-2> . Then, p-type well regions 2 and 202, and an n-type well region 203 are made, making use of heat diffusion.
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