A method of fabricating a semiconductor device is disclosed. The method includes defining an electrode on a semiconductor substrate; forming a spacer on at least one sidewall of the electrode; performing a process operation on the semiconductor substrate using the spacer as a mask and forming a material layer on the top or the surface of the semiconductor substrate and the electrode; and removing the spacer by steps of performing a wet etching process at a temperature in a range of 100° C. to 150° C. to etch the spacer using an acid solution containing phosphoric acid as an etchant. With respect to another aspect, a method of removing a spacer is also disclosed. The method includes performing a wet etching process at a temperature in a range of 100° C. to 150° C. to etch the spacer using an acid solution containing phosphoric acid as an etchant.