Patent ID: 8044457

Claim:
A voltage clamp device comprising: (a) a substrate; (b) a lightly doped first deep region formed in the substrate; (c) a lightly doped second deep region formed in the substrate adjacent the first deep region, wherein a lateral boundary is formed between the first and second deep regions; (d) highly doped first and second shallow regions formed in the first deep region; (e) highly doped third and fourth shallow regions formed in the second deep region, wherein the third shallow region has a lateral surface facing the first deep region; (f) a first terminal electrically connected to the first shallow region; (g) a second terminal electrically connected to the third shallow region; and (h) a gate structure comprising an insulating layer and a gate electrode disposed on the insulating layer, at least a portion of the gate structure overlapping the second deep region, wherein the gate structure extends from over the lateral surface of the third shallow region to over the boundary; wherein (i) the second shallow region is located between the first and third shallow regions, and the third shallow region is located between the second and fourth shallow regions, and (ii) the first deep region and the first and third shallow regions are of a first conductivity type, and the second deep region and the second and fourth shallow regions are of a second, opposite conductivity type.