Semiconductor process for manufacturing semiconductor device with increased operating voltages

A semiconductor device, comprising:

• a semiconductor layer of a first conductivity type;
• an epitaxial layer of said first conductivity type formed over said semiconductor layer, said epitaxial layer having a face and a first thickness;
• a first buried layer region of a second conductivity type opposite said first conductivity type at the interface of said semiconductor layer and said epitaxial layer, said first buried layer region doped with two dopants of a second conductivity type, one of the two dopants being a faster-diffusing dopant than the other one of the two dopants, the implant dosage of the faster-diffusing dopant being substantially less than the implant dosage of the other one of the two dopants, said first buried layer region including a heavily doped region and a lightly doped extension region, said heavily doped region extending vertically a first distance from said interface, said lightly doped extension region extending vertically a second distance from said interface, said second distance being greater than said first distance and lees than said thickness;
• and
• a first region of said second conductivity type formed at said face of said epitaxial layer over said lightly doped extension region and in electrical contact with said lightly doped extension region.