Plasma treatment method and apparatus

A plasma treatment apparatus for plasma-treating a substrate under a decompressed atmosphere, comprising:

• a chamber;
• an opening, formed in said chamber, for allowing the substrate to be conveyed into the chamber or taken out thereof;
• means for exhausting the chamber of gases;
• a lower electrode on which the substrate is placed;
• an upper electrode located inside the chamber and facing the lower electrode;
• gas supply means for supplying a treatment gas from the upper electrode toward the substrate placed on the lower electrode;
• a ring member located in the chamber and detachably fitted around the lower electrode;
• lift means for vertically moving the lower electrode together with the ring member;
• and
• a baffle plate fitted around the ring member, said baffle plate being moved to a position that is higher in level than an upper end of the opening of the chamber when the ring tember is lifted by said lift means, the baffle plate at said position serving to shield a region near the opening of the chamber from a plasma generation region and also to allow reaction products which are produced by heat or plasma, to be adhered to the baffle plate, said baffle plate being also movable by said lift means to a position that is higher in level than a lower end of the opening of the chamber.