Abstract: A structure is designed with a lightly doped substrate (316) having a first conductivity type and a face. A first lightly doped region (314) has a second conductivity type and is formed within the lightly doped substrate. A first heavily doped region (308) has the first conductivity type and is formed at the face and extends to a first depth within the first lightly doped region. A second heavily doped region (312) has the second conductivity type and is formed at the face abutting the first heavily doped region. The second heavily doped region extends to a second depth and is at least partly within the first lightly doped region. A first isolation region (304) is formed at the face, abutting at least one of the first and second heavily doped regions. The first isolation region extends to a third depth that is greater than either of the first and the second depths.