A semiconductor device, comprising: a substrate (12, 102); a patterned buried layer (41, 106) in the substrate (12, 102) having a first conductivity type, a first portion (42, 112) and a second portion (44, 114), wherein the first and second portions (42, 112, 44, 114) each have a first end and a second end; a first deep well (40, 134) in the substrate (12, 102) having a second conductivity type and a first doping level, wherein the first deep well (40, 134) is separated from the patterned buried layer (41, 106); a highly doped p-type low voltage well (54, 136) in the first deep well (40, 134) having the second conductivity type and a second doping level that is greater than the first doping level; a shallow doped layer at the surface of the substrate having the second conductivity type in the first deep well and in the highly doped p-type low voltage well; wherein: the first ends of the patterned buried layer having a smaller cross-section than the second ends of the patterned buried layer, and the first ends with the smaller cross-section are adjacent to one another; the highly doped p-type low voltage well (54, 136) in the first deep well (40, 134) is directly over the first ends of the first and second portions (42, 112, 44, 114) and extends from the shallow doped layer through the first deep well into a separation between the patterned buried layer (41, 106) and the first deep well. a substrate (12, 102); a patterned buried layer (41, 106) in the substrate (12, 102) having a first conductivity type, a first portion (42, 112) and a second portion (44, 114), wherein the first and second portions (42, 112, 44, 114) each have a first end and a second end; a first deep well (40, 134) in the substrate (12, 102) having a second conductivity type and a first doping level, wherein the first deep well (40, 134) is separated from the patterned buried layer (41, 106); a highly doped p-type low voltage well (54, 136) in the first deep well (40, 134) having the second conductivity type and a second doping level that is greater than the first doping level; a shallow doped layer at the surface of the substrate having the second conductivity type in the first deep well and in the highly doped p-type low voltage well; wherein: the first ends of the patterned buried layer having a smaller cross-section than the second ends of the patterned buried layer, and the first ends with the smaller cross-section are adjacent to one another; the highly doped p-type low voltage well (54, 136) in the first deep well (40, 134) is directly over the first ends of the first and second portions (42, 112, 44, 114) and extends from the shallow doped layer through the first deep well into a separation between the patterned buried layer (41, 106) and the first deep well. the first ends of the patterned buried layer having a smaller cross-section than the second ends of the patterned buried layer, and the first ends with the smaller cross-section are adjacent to one another; the highly doped p-type low voltage well (54, 136) in the first deep well (40, 134) is directly over the first ends of the first and second portions (42, 112, 44, 114) and extends from the shallow doped layer through the first deep well into a separation between the patterned buried layer (41, 106) and the first deep well.