Abstract: A method of fabricating a contact window of a semiconductor device, whereby a contact window of a semiconductor device is increased to offset any incline phenomenom and avoid unwanted increase in contact sheet resistance, comprises forming a lower conductive member on a semiconductor substrate, forming a first insulative film on the lower conductive member, the first insulative film being formed of an insulative material doped with impurities at a first level of concentration, the first insulative film having a wet etch rate that is proportional to the level of concentration of impurities, forming a second insulative film on the first insulative film, the second insulative film being formed of an insulative material doped with impurities at a second level of concentration that is lower than the first level of concentration of impurities, the second insulative film also having a wet etch rate that is proportional to the level of concentration of impurities, opening a contact window and exposing the lower condu

Abstract: A fabrication method of a semiconductor device is disclosed. Particularly, in the process of forming a gate oxide film on a semiconductor substrate, the method for forming a gate oxide film of a semiconductor device comprises the steps of first-annealing the semiconductor substrate in a nitrogen (N.sub.2) atmosphere; forming a gate oxide film by wet-oxidizing the annealed semiconductor substrate at a low temperature in a mixed gas atmosphere of oxygen (O.sub.2) and hydrogen (H.sub.2); and second-annealing the semiconductor substrate where gate oxide film has been formed, at a high temperature in a nitrogen (N.sub.2) atmosphere. Accordingly, the thinning phenomenon of the gate oxide film near the field oxide film is prevented and the instability such V.sub.FB in the conventional field oxidation method is considerably recovered. Also, the field concentration phenomenon is decreased and tolerance to dielectric breakdown is increased.