Patent ID: 6603155
Filing Date: 2003-08-05
Classification: H01L

Abstract:
A semiconductor overvoltage protection device in the form of a four layer diode having:first and third layers of a first conductivity semiconductor material; second and fourth layers of a second conductivity type semiconductor material; 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 having a greater impurity concentration than the third layer; and a second buried region of the same conductivity type as and of higher impurity concentration than said first buried region in said first buried region adjacent to said junction; wherein: said first layer is penetrated by a plurality of dots of said second layer extending through said first layer; one of said 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 said second buried region; and said dots do not overlie portions of said second buried region.