Patent ID: 7682955

Claim:
A method for forming a deep well region of a power device, comprising: providing a substrate with a first sacrificial layer thereon; forming a first patterned mask layer on the first sacrificial layer exposing a first open region; performing a first doping process to the first open region to form a first sub-doped region; removing the first patterned mask layer and the first sacrificial layer; forming an epitaxial layer on the substrate; forming a second sacrificial layer on the epitaxial layer; forming a second patterned mask layer on the second sacrificial layer exposing a second open region; performing a second doping process to the second open region to form a second sub-doped region; removing the second patterned mask layer; performing an annealing process to make the first and the second sub-doped regions form a deep well region; and removing the second sacrificial layer.