Patent ID: 6653689
Filing Date: 2003-11-25
Classification: H01L

Abstract:
A semiconductor device having an electrostatic protection circuit included therein such that static charge of a positive polarity that is applied to a signal terminal is discharged to a VSS power line side, the semiconductor device comprising:a semiconductor substrate; p-type and n-type well regions formed on the semiconductor substrate; a first p-type impurity diffusion region formed in a surface layer of the p-type well region; a first n-type impurity diffusion region which is formed in a surface layer of the p-type well region and which is electrically isolated from the first p-type impurity diffusion region; a second p-type impurity diffusion region which is formed in a surface layer of the p-type well region and which is electrically isolated from the first n-type impurity diffusion region; a second n-type impurity diffusion region which is formed in a surface layer of the p-type and n-type well regions adjacent to the second p-type impurity diffusion region; a third n-type impurity diffusion region materially connected to, and located below surfaces of the second p-type and second n-type impurity diffusion regions in the p-type well region; a third p-type impurity diffusion region materially connected to a lower surface of the third n-type impurity diffusion region; and a low-resistance layer formed on a surface of the second p-type and n-type impurity diffusion regions, wherein a Zener diode is formed by a p-n junction between the third n-type and p-type impurity diffusion regions, wherein an NPN bipolar transistor is formed by the first n-type impurity diffusion region, the p-type well region, and the n-type well region, wherein a PNP bipolar transistor is formed by the second p-type impurity diffusion region, and the third n-type impurity diffusion region and the third p-type impurity diffusion region in which the Zener diode is formed, wherein the signal terminal is connected to the second p-type and n-type impurity diffusion regions through the low-resistance layer, and wherein the VSS power line is connected to the first p-type and n-type impurity diffusion regions.