PLASMA GENERATING APPARATUS

PURPOSE:To prevent glow discharge in a gas path, by introducing process gas into a discharge chamber between both high frequency electrodes so that the gas is not brought into contact with the electrodes before the gas enters into the discharge chamber, and making the distance of a gas introducing path in the direction of an electric field shorter than the thickness of an ion sheath in the discharge chamber. CONSTITUTION:An electric insulator 13 comprising Teflon, alumina and the like is provided between a planar electrode 1 and a tubular electrode 2. A gas introducing tube 14 comprising an insulator is inserted into the electric insulator in the lateral direction. An annular slit-shaped gas flowing path 15 is formed in the insulator 13 and a quartz pipe 5 so as to communicate the introducing tube and a discharge chamber 3. A length (width) d1 of the gas flowing path in the direction of a high frequency electric field (direction of arrows) is thin and shorter than a thickness d2 of an ion sheath 16, which is generated between a plasma region in the discharge chamber and the electrode 1. Process gas is not brought into contact with the electrodes 1 and 2 before the gas enters into the discharge chamber 3. The gas is introduced through a space, in which the distance in the direction of the applied electric field is less than the thickness of the ion sheath. Therefore, glow discharge is not generated in the gas flowing path 15.