PROBLEM TO BE SOLVED: To realize both of the stabilization of plasma discharge and the suppression of sputtering by an antenna and to provide an optimum capacitive coupling between the antenna and the plasma by providing capacitors intervened between the grounding side of an antenna or a plurality of antennas.
SOLUTION: A vacuum vessel 1 is provided with an antenna 8 composed of looped conductive material. There are an antenna 8 formed by applying an insulating coating of an insulating material around the outer circumference of the antenna conductor and an antenna 8 having an antenna conductor in pure metal without any insulating coating. A high frequency power supply 9 is connected to one end of the antenna 8 and a floating capacitor 10 is connected across the grounding in the other end side. Because the floating capacitor 10 is a variable capacity, the high frequency voltage distribution is changed on the antenna 8 by changing the capacity Cf so that the capcitive coupling between the antenna 8 and the plasma is controlled.