the present invention provides a system for efficiently producing versatile , high - precision mos device structures in which straight regions dominate the device &# 39 ; s behavior , providing minimum geometry devices that precisely match large devices , in an easy , efficient and cost - effective manner . the present invention provides methods and apparatus for producing double diffused semiconductor devices that minimize performance impacts of end cap regions . the present invention provides a mos structure having a moat region , and an oxide region overlapping the moat region . a double - diffusion region is formed within the oxide region , having end cap regions that are effectively deactivated utilizing geometric and implant manipulations .