A method for selectively etching a high-k dielectric layer with respect to a polysilicon material is provided. The high-k dielectric layer is partially removed by Ar sputtering, and then the high-k dielectric layer is etched using an etching gas comprising BCl3. The high-k dielectric layer and the polysilicon material may be formed on a substrate. In order to partially remove the high-k dielectric layer, a sputtering gas containing Ar is provided into an etch chamber in which the substrate is placed, a plasma is generated from the sputtering gas, and then the sputtering gas is stopped. In order to etch the high-k dielectric layer, the etching gas is provided into the etch chamber, a plasma is generated from the etching gas, and then the etching gas is stopped.