Plasma uniformity of inductively coupled plasma reactor with helical heating coil

For a plasma reactor consisting of a reactor and an inductively coupled plasma source, a simple method to adjust the plasma uniformity of the reactor is proposed. The source has a helical resonator structure with a helical coil short-circuited at one end and open-circuited at the other end. To adjust the plasma uniformity, this method uses an RF tap which is located at the helical coil and feeds RF power into the plasma source. Depending on the location of the RF tap, the axial density profile at the source changes and that adjusts the plasma uniformity of the reactor. The achieved plasma uniformity within a diameter of 120 mm is less than ±2.5%. Effects of various process conditions on plasma uniformity are also examined. It is concluded that the proposed method has a great potential for uniformity adjustment in an advanced plasma processing system