| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology for efficiently protecting the internal circuit of a semiconductor integrated circuit. SOLUTION: An n-type diffusion layer 115 is so formed as to surround a p<SP>+</SP>-type diffusion layer 114b. Since the concentration of n-type dopants around a parasitic diode 124 increases due to the existence of the n-type diffusion layer 115, the breakdown voltage of the parasitic diode 124 connected to a collector electrode is set lower than that of a diode 122 connected to an emitter electrode. This is due to the fact that the breakdown voltage of a diode is determined by the dopant concentration around it, and that the higher the dopant concentration is, the lower the breakdown voltage becomes. Therefore, an inverse current is easily caused to flow in the parasitic diode 124, resulting in increasing the clamping performance of the parasitic diode 124 connected between a high potential power source 102 and a low potential power source 103 and hence suppressing the damages to the internal circuit 121 due to static electricity applied to the terminals of the power sources. COPYRIGHT: (C)2006,JPO&NCIPI
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