SEMICONDUCTOR DEVICE INCLUDING MOS TRANSISTOR CONTROLING HIGH VOLTAGE AND METHOD OF FORMING THE SAME

摘要

A semiconductor device having a MOS transistor controlling a high voltage and a method for forming the semiconductor device are provided to increase a breakdown voltage of a high voltage MOS(Metal Oxide Semiconductor) transistor by minimizing a focusing of an electric field. A semiconductor device includes a field insulation film, a gate(116), a channel region, a highly doped region, and a lightly doped region(110a). The field insulation film defines first and second substrate regions. The gate is arranged to traverse over the first substrate region. The channel region is defined in the first substrate region under the gate and includes first and second portions. The first portion has a first width in a channel width direction. The second portion has a second width. The highly doped region is formed on the second substrate region. The lightly doped region is formed at one side of the channel region and encloses a side surface and a bottom surface of the highly doped region. The first portion is arranged between the second substrate region and the second portion. The first portion is close to the field insulation film between the first and second substrate regions. The first width is smaller than the second width.