Structures of high voltage device and low voltage device, and method of manufacturing the same

A method for manufacturing a high voltage device and a low voltage device comprising steps of:

• (a) depositing a first oxidation film and a nitride film sequentially on a SOI substrate where a lower substrate, a buried oxidation film and an upper silicon layer are sequentially stacked;
• (b) removing the nitride film and the first oxidation film of the high voltage device region by etching, after defining the high voltage device region on a total structure;
• (c) forming the upper silicon layer of the high voltage device region thinner than the upper silicon layer of the low voltage device region by growing a second oxidation film in the high voltage device region;
• (d) removing the second oxidation film and the remaining portions of the nitride film and the first oxidation film;
• (e) forming the high voltage device region and the low voltage device region by etching the upper silicon layer, after defining a device isolation region;
• (f) forming a p-well in the low voltage device region, and a p-well and a drift region in the high voltage device region;
• (g) forming a thin gate insulation film in the low voltage device region, and a thick gate insulation film in the high voltage device region;
• (h) forming a gate electrode, a LDD region, a sidewall oxidation film, a source region and a drain region in the low voltage device region and the high voltage device region, respectively;
• and
• (i) forming a source electrode and a drain electrode, after depositing an interlayer insulation film on an upper surface of a total structure.