Semiconductor structure and methods for forming the same

A method for forming a semiconductor device, comprising:

• providing a substrate having a first conductivity type;
• forming an epitaxial layer on the substrate, wherein the epitaxial layer has the first conductivity type;
• forming a first doping region in the epitaxial layer, wherein the first doping region extends from a top surface of the epitaxial layer in a direction toward the substrate, wherein the first doping region has the first conductivity type;
• forming a first device in the first doping region, wherein the substrate functions as a drain electrode;
• forming a second doping region in the epitaxial layer, wherein the second doping region extends from the top surface of the epitaxial layer in a direction toward the substrate, the second doping region has a second conductivity type, the second doping region is located at a side of the first doping region, and a portion of the epitaxial layer extends between the first doping region and the second doping region to separate the first doping region and the second doping region;
• and
• forming a second device in the second doping region.