Deep trench isolation with segmented deep trenches

A semiconductor device (100) has a first trench (102) and a second trench (104) of a trench structure (116) in a substrate (108). The second trench (104) is separated from the first trench (102) by a trench space (106) that is less than a first trench width (118) of the first trench (102) and less than a second trench width (120) of the second trench (104). The trench structure (116) includes a doped sheath (148) having a first conductivity type that contacts and laterally surrounds the first trench (102) and the second trench (104). A doped sheath (148) extends from the top surface (114) to the isolation layer (110) and from the first trench (102) to the second trench (104) across the trench space (106). The semiconductor device (100) includes a first region (150) and a second region (152) in the semiconductor layer (112) having an opposite second conductivity type. The first region (150) and the second region (152) are separated by the first trench (102), the second trench (104), and the doped sheath (148).