PLASMA TREATING APPARATUS

PURPOSE:To remove attached foreign material completely, by providing matching circuits for supplying a high frequency voltage both in a mounting electrode and a counter electrode, switching the electric connecting state of a high frequency voltage source and said two matching circuits at the time of plasma treatment and at the time of cleaning, thereby generating a plasma region in a wide range on the inner wall of the treating chamber at the time of cleaning. CONSTITUTION:At the time of plasma treatment of a material to be treated, a high frequency voltage is supplied to a mounting electrode 2 by switches 20a and 20b through a matching circuit 6 on the side of the mounting electrode 2. A counter electrode 4 is grounded. Thus desired plasma treatment is performed. Meanwhile, at the time of cleaning, the high frequency voltage is supplied to the counter electrode 4 by the switches through a matching circuit 16 on the side of the counter electrode 4. The mounting electrode 2 is still connected to the matching circuit 6 on the side of said mounting electrode. Control is performed so that the discharge impedance between the counter electrode and the inner wall of the treating chamber becomes lower than the discharge impedance between the electrodes. As a result, the plasma spreads on the inner wall of the treating chamber and on the rear surface of the counter electrode. Thus, foreign material, which is attached to those places, can be efficiently removed.