Method of fabricating semiconductor device having gate dielectrics with different thicknesses

Abstract

A method of fabricating a semiconductor device including gate dielectrics having different thicknesses may be provided. A method of fabricating a semiconductor device may include providing a substrate having a higher voltage device region and a lower voltage device region, forming an anti-oxidation layer on the substrate, and selectively removing portions of the anti-oxidation layer on the substrate. The method may also include performing a first thermal oxidization on the substrate to form a field oxide layer on the selectively removed portions of the anti-oxidation layer, removing the anti-oxidation layer disposed on the higher voltage device region, performing a second thermal oxidization on the substrate to form a central higher voltage gate oxide layer on the higher voltage device region, removing the anti-oxidation layer disposed on the lower voltage device region, and performing a third thermal oxidization on the substrate to form a lower voltage gate oxide layer on the lower voltage device region.