Plasma Processing Apparatus

Abstract

A plasma processing apparatus includes a stage which is a lower electrode, an upper electrode which is a counter electrode for the lower electrode, and a processing chamber in which the lower and the upper electrodes are placed. The apparatus supplies a gas to a plasma generation space located between the lower and the upper electrodes to generate a plasma so that a processing object is subjected to plasma processing. In the apparatus, the upper electrode is formed up of a body portion having a gas supply port, a gas-permeable porous plate located on the underside of the body portion so as to close the gas supply port, and a support member for supporting the outer edge portion of the porous plate. Slits for absorption of strain due to thermal expansion in the plasma processing are formed at a pitch in the outer edge portion of the porous plate.

1 . A plasma processing apparatus comprising a first electrode unit having a placement surface on which a processing object is to be placed, and a second electrode unit facing the placement surface of the first electrode unit, and a processing vessel that defines a processing chamber in which the first and second electrode units are to be located, wherein a plasma-generation gas is supplied into a plasma processing space between the first and second electrode units so as to generate a plasma and then plasma processing on the processing object is performed,
 the second electrode unit comprising:
 a body portion having a gas supply port communicating with a gas supply passage; 
 a porous plate which is placed so as to cover the gas supply port and face the plasma processing space and which has gas permeability such that the gas supplied from the gas supply port is supplied to the plasma processing space through inside thereof; and 
 a support member which supports the porous plate on its outer edge portion so that the porous plate is fixedly placed to the body portion, wherein 
   a plurality of cutout portions are formed in the outer edge portion of the porous plate at a specified interval pitch so as to extend through the plate in a thicknesswise direction thereof.   
     
     
         2 . The plasma processing apparatus as defined in  claim 1 , wherein
 the porous plate has a disc-like shape,   the support member includes an annular member located on a lower surface of the body portion, and a protruding portion annularly protruded inward of an end portion of the annular member, and   the outer edge portion of the porous plate located inward of the annular member in the lower surface of the body portion is supported by the protruding portion from below.   
     
     
         3 . The plasma processing apparatus as defined in  claim 2 , wherein the protruding portion is formed so as to project over the individual cutout portions so that gaps of the individual cutout portions of the porous plate are closed against the plasma processing space. 
     
     
         4 . The plasma processing apparatus as defined in  claim 3 , wherein
 the porous plate has a support region which is an annular region located in an outer edge portion of the disc-like shape and on which the plate is supported by the protruding portion of the support member, and a gas passage region which is a circular region located inside the outer edge portion of the disc-like shape and surrounded by the support region and in which the plasma-generation gas is allowed to pass therethrough, and   each of the cutout portions is formed in the support region so as to be in close proximity to a boundary with the gas passage region.   
     
     
         5 . The plasma processing apparatus as defined in  claim 4 , wherein in each of the cutout portions of the porous plate, at least an inner circumferential surface on one side closer to a center of the porous plate is formed into a curved surface. 
     
     
         6 . The plasma processing apparatus as defined in  claim 5 , wherein in the protruding portion, each of the cutout portions is so formed that an entirety of its inner circumferential surface becomes a curved surface. 
     
     
         7 . The plasma processing apparatus as defined in  claim 1 , wherein each of the cutout portions has a slit-like shape.