Patent ID: 7863681

Claim:
A semiconductor structure comprising: first and second body-material regions of a semiconductor body having an upper surface, the body-material regions doped with semiconductor dopant of a first conductivity type so as to be of the first conductivity type; and first and second zones of a second conductivity type opposite to the first conductivity type situated in the semiconductor body along its upper surface, the first and second body-material regions respectively extending below the first and second zones and respectively meeting them so as to respectively form first and second pn junctions with the first and second zones such that (a) each pn junction reaches a maximum depth below the body's upper surface, (b) the dopant of the first conductivity type is present in both zones and has a concentration which locally reaches first and second subsurface maximum concentrations at respective first and second subsurface body-material locations situated respectively in the first and second body-material regions and respectively extending laterally below the first and second zones, (c) the first and second subsurface body-material locations occur no more than 10 times deeper below the body's upper surface respectively than the maximum depths of the first and second pn junctions, and (d) the concentration of the dopant of the first conductivity type (i) decreases by at least a factor of 10 in moving upward from the first subsurface body-material location along a selected first vertical line through the first zone to the body's upper surface, (ii) decreases substantially monotonically in moving from the first subsurface body-material location along the first vertical line to the first pn junction, and (iii) reaches at least one additional subsurface maximum concentration in moving upward from the second subsurface body-material location along a selected second vertical line through the second zone to the body's upper surface.