| 摘要 |
A method for forming a semiconductor transistor having high voltage is disclosed. The method includes firstly providing a semiconductor substrate, then forming a well having a first conductivity type in the substrate. Next, a first sub-well having the first conductivity type, and a second sub-well having a second conductivity type contrary to the first conductivity type, are formed in the well. After defining a drift region over the substrate and forming a drift region, in which a substantial portion of the drift region abuts the second sub-well, a field oxide region is formed on the drift region. A gate region is then formed over the substrate, in which a portion of the gate region abuts the field oxide region. Finally, ion implantation is performed to form a source/drain region in the substrate using the gate region and the field oxide region as a mask.
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