A semiconductor device includes: a substrate including a first epitaxial layer that has a first electrical type, and a second epitaxial layer; a transistor that includes a source region and an insulating spacer; an inner surrounding structure including an annular trench and an insulating spacer; an outer surrounding structure that has a second electrical type opposite to the first electrical type, and that is disposed adjacent to an upper surface of the second epitaxial layer to surround and contact the inner surrounding structure; and a conductive structure connecting to the source region, and the inner and outer surrounding structures.