An apparatus includes an upper electrode and a lower electrode for supporting a wafer disposed opposite each other within a process chamber. A first RF power supply configured to apply a first RF power having a relatively higher frequency, and a second RF power supply configured to apply a second RF power having a relatively lower frequency is connected to the lower electrode. A variable DC power supply is connected to the upper electrode. A process gas is supplied into the process chamber to generate plasma of the process gas so as to perform plasma etching.