Bourns Incorporated

Power Innovations, Ltd.

Jeremy Paul Smith

Steven Wilton Byatt

Russell Duane

A semiconductor overvoltage protection device in the form of a four layer diode has first and third layers of a first conductivity semiconductor material, second and fourth layers of a second conductivity type semiconductor material and a first buried region of the first conductivity type in the third layer adjacent to the junction between the second and third layers. The buried region has a greater impurity concentration than the third layer. The first layer is penetrated by a plurality of dots of the second layer extending through the first layer and the first buried region lies wholly beneath the second layer and is laterally offset from the dots and the first layer.

Overvoltage protection device

A semiconductor device has a PN junction between first and second regions of the device in which in the intended operation of the device reverse breakdown of the junction occurs. The first region is of lower impurity concentration than the second region and a first buried region of the same conductivity type as and of higher impurity concentration than the first region is provided in the first region adjacent to the junction. A second buried region of the same conductivity type as and of higher impurity concentration than the first buried region is provided in the first buried region and one of the first and second buried regions is formed with a plurality of separate regions of small area arranged so that reverse breakdown of the junction preferentially occurs through the second buried region.

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Wollaston, United Kingdom

Jeremy Paul Smith