| 摘要 |
PROBLEM TO BE SOLVED: To restrain variation with time in a reverse breakdown voltage obtained by the reverse breakdown voltage of a pn junction in a semiconductor device functioning as a constant voltage element. SOLUTION: The reverse breakdown voltage in a diode is adjusted. The diode is formed at a portion to an n-type impurity diffusion layer 14 formed toward the inside from the surface of an active region 13 of a p-type semiconductor substrate 11. For that purpose, a p-type impurity diffusion layer 18 is provided directly below the n-type impurity diffusion layer 14. Additionally, the p-type impurity diffusion layer 18 is formed separately from a device isolation insulating film 12. As a result, the reverse junction breakdown position of the diode can be separated from the device isolation insulating film 12, the injection of a carrier being generated by a breakdown phenomenon to a device isolation oxide film is restrained, and hence the variation with time in the reverse breakdown voltage is restrained. COPYRIGHT: (C)2004,JPO
|
