A method for fabricating a high voltage semiconductor transistor includes growing a first well region over a substrate having a first conductivity type, the first well region having a second type of conductivity. First, second and third portions of a second well region having the first type of conductivity are doped into the first well region. A first insulating layer is grown in and over the first well portion within the second well region. A second insulating layer is grown on the substrate over the third portion of the second well region. An anti-punch through region is doped into the first well region. A gate structure is formed on the substrate. A source region is formed in the first portion of the second well region on an opposite side of the gate structure from the first insulating layer. A drain region is formed in the first well region.