Abstract: A spacer is formed on a side wall of a gate electrode formed over a substrate, and a dielectric interlayer is then formed over the substrate, the gate electrode and the spacer. A region of the dielectric interlayer is then subjected to a first etching process using an etching gas. An emission amount of a chemical compound emitted during the first etching process is detected, where the chemical compound is produced by a chemical reaction of the etching gas and the spacer. The region of the dielectric interlayer is then subjected to a second etching process upon detecting that the emission amount of the chemical compound has reached a given level. The second etching process may be continued until a contact hole is defined in the dielectric interlayer.

Abstract: A spacer is formed on a side wall of a gate electrode formed over a substrate, and a dielectric interlayer is then formed over the substrate, the gate electrode and the spacer. A region of the dielectric interlayer is then subjected to a first etching process using an etching gas. An emission amount of a chemical compound emitted during the first etching process is detected, where the chemical compound is produced by a chemical reaction of the etching gas and the spacer. The region of the dielectric interlayer is then subjected to a second etching process upon detecting that the emission amount of the chemical compound has reached a given level. The second etching process may be continued until a contact hole is defined in the dielectric interlayer.