Power module including a semiconductor device with parasitic diode

A semiconductor device, comprising:

• a substrate;
• an epitaxial layer on the substrate;
• a first well region in the epitaxial layer;
• a source region in the first well region, wherein the substrate, the epitaxial layer and the source region comprise a plurality of dopants of a first semiconductor type;
• a source contact, wherein a bottom of the source contact is lower than a bottom of the first well region;
• a base region wrapping around a sidewall of the source contact;
• and
• a second well region wrapping around the base region, wherein the first well region, the base region and the second well region comprise a plurality of dopants of a second semiconductor type, the second semiconductor type is different from the first semiconductor type, and a doping concentration of the base region is higher than a doping concentration of the first well region and a doping concentration of the second well region, and the second well region is closer to the substrate than the first well region is.