Patent ID: 7972918

Claim:
A method of fabricating a semiconductor structure, the method comprising: introducing semiconductor dopant of a first conductivity type into a semiconductor body to define first and second body-material regions such that each body-material region is of the first conductivity type; and introducing semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to define first and second zones of the second conductivity type such that, upon completion of fabrication of the structure, (a) the first and second body-material regions respectively form first and second pn junctions with, and respectively extend laterally below, the first and second zones, (b) each pn junction extends to a maximum depth below an upper surface of the semiconductor body, (c) semiconductor dopant of the first conductivity type is present in both zones, (d) all semiconductor dopant of the first conductivity type in the semiconductor body 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, (e) 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 (f) the concentration of all 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.