High-voltage semiconductor device, semiconductor device and method of forming thereof

A semiconductor device and its method of manufacture are provided. Embodiments include forming a first doped region and a second doped region. The first and second doped regions may form a double diffused drain structure as in an HVNMOS transistor. A gate-side boundary of the first doped region underlies part of the gate electrode. The second doped region is formed within the first doped region adjacent the gate electrode. A gate-side boundary of the second doped region is separated from a closet edge of a gate electrode spacer by a first distance. An isolation region-side boundary of the second doped region is separated from a closet edge of a nearest isolation region by a second distance.