Provided is a method of fabricating a semiconductor device including the following steps. A substrate is provided. A material layer having an opening is formed on the substrate. A first passivation material layer is formed on sidewalls of the opening and on the substrate. A treatment process is performed to the first passivation material layer to form a second passivation material layer. A first surface of the second passivation material layer and a second surface (at an inner side) of the second passivation material layer are differ in a property, and the first surface is located at a side of the second passivation material layer relatively away from the material layer.