US Patent 7700493 Method for fabricating semiconductor device

A method for fabricating a semiconductor device includes forming a first pattern over a substrate, forming an oxide-based layer over the first pattern, forming a hard mask layer over the oxide-based layer, etching the hard mask layer at a first substrate temperature, and etching the oxide-based layer to form a second pattern, wherein the oxide-based layer is etched at a second substrate temperature which is greater than the first substrate temperature using a gas including fluorine (F) and carbon (C) as a main etch gas.