Semiconductor device

A semiconductor device, comprising:

• a first epitaxial layer, a second epitaxial layer, and a third epitaxial layer sequentially stacked on a substrate, the first and third epitaxial layers having a first conductivity type, the second epitaxial layer having a second conductivity type;
• a first diffusion prevention layer between the substrate and the first epitaxial layer;
• a second diffusion prevention layer between the first epitaxial layer and the second epitaxial layer;
• and
• a third diffusion prevention layer between the second epitaxial layer and the third epitaxial layer,
• wherein the first diffusion prevention layer comprises silicon (Si) and a first diffusion prevention element,
• wherein the second diffusion prevention layer comprises silicon (Si) and a second diffusion prevention element, and
• wherein the first diffusion prevention element is different from the second diffusion prevention element.

A semiconductor device, comprising:

• a first epitaxial layer, a second epitaxial layer, and a third epitaxial layer sequentially stacked on a substrate, the first and third epitaxial layers having a first conductivity type, the second epitaxial layer having a second conductivity type;
• a first diffusion prevention layer between the first epitaxial layer and the second epitaxial layer;
• a second diffusion prevention layer between the second epitaxial layer and the third epitaxial layer;
• and
• a power delivery network layer on a bottom surface of the substrate,
• wherein the substrate has a first thickness in a vertical direction,
• wherein a total thickness of the first to third epitaxial layers, which are sequentially stacked, is a second thickness, and
• wherein the first thickness is larger than the second thickness.