A method of fabricating a semiconductor device includes forming a gate dielectric layer comprising an oxide, and at least one conductive layer on a substrate, forming a mask on the conductive layer and patterning the at least one conductive layer by etching the at least one conductive layer using the mask as an etch mask to thereby form a gate electrode, wherein the oxide of the gate dielectric layer and the material of the at least one conductive layer are selected such that a byproduct of the etching of the at least one conductive layer, formed on the mask during the etching of the at least one conductive layer, comprises an oxide having a higher etch rate with respect to an etchant than the oxide of the gate dielectric layer.