Patent ID: 8790984

Claim:
A method, comprising: providing a base wafer; implanting atoms of a first conductivity type as a dopant into a region of the base wafer; driving the implanted atoms to a depth sufficient to form a first well; patterning and implanting atoms of the first conductivity type to form a second well inside the region to a dopant concentration greater than a concentration of the dopant in the region; patterning and implanting atoms of a second conductivity type to form a third well inside the second well; and patterning and implanting atoms of the first conductivity type to form a layer overlying the third well; driving the implanted atoms to a depth sufficient to form the second well and the third well by subjecting the wafer to a high temperature greater than about 1000 degrees C.; performing a field oxide process that defines an emitter region having a rectangular shape disposed in a center portion of the layer, a base region having a shape of a rectangular ring surrounding and concentric with the emitter region, and a collector region having a shape of a rectangular ring surrounding and concentric with the base region, the emitter region, the base region and the collector region being isolated from each other; patterning and implanting atoms of the first conductivity type in the emitter and collector regions, whereby the emitter and collector regions are doped to a higher concentration than that of the layer and whereby the emitter extends through the layer into the third well and the collector region extends into the second well; and patterning and implanting atoms of the second conductivity type in the base region, whereby the base region is doped to a higher concentration than that of the third well and whereby the base region extends through the layer into the third well.