Plasma processing apparatus

Abstract

In an atmospheric-pressure plasma processing apparatus, a first metal surface 21 a of a first stage portion 21 of a stage 20 is exposed and an object to be processed W composed of a dielectric material is placed on the first metal surface 21 a . A second stage portion 22 is disposed on a peripheral edge of the first stage portion 21 . A solid dielectric layer 25 is disposed on a second metal 24 of the second stage portion 22 . A peripheral portion of the object W is placed on an inner dielectric portion 26 of the solid dielectric layer 25 . An electrode 11 generates a run up discharge D 2 in a second movement range R 2 above the second stage portion 22 . Then, the electrode 11 is moved to a first movement range R 1 above the first stage portion 21 and generates a regular plasma discharge D 1.

1 . A plasma processing apparatus for processing a surface of an object to be processed which is mainly composed of a dielectric material by exposing said object to a near atmospheric-pressure plasma discharge, said apparatus comprising:
 a stage including a first stage portion having an exposed first metal surface and a second stage portion having a second metal surface covered with a solid dielectric layer and disposed on an outer peripheral portion of said first stage portion, said object being placed on said first metal surface of said first stage portion such that a peripheral portion of said object is protruded toward said second stage portion; and   an electrode relatively movable with respect to said stage within a range including a first movement range in which said electrode is opposed to said first stage portion to generate said plasma discharge and a second movement range in which said electrode is opposed to said second stage portion.   
   
   
       2 . A plasma processing apparatus according to  claim 1  wherein a thickness and a dielectric constant of said solid dielectric layer of said second stage portion are set such that said plasma discharge is generated between said electrode in said second movement range and said second stage portion. 
   
   
       3 . A plasma processing apparatus according to  claim 1  wherein said solid dielectric layer of said second stage portion includes an inner dielectric portion on which said peripheral portion of said object is to be placed and an outer dielectric portion disposed on an opposite side of said inner dielectric portion from said first stage portion, said outer dielectric portion being more protruded than said peripheral portion of said object; and
 wherein, of said inner dielectric portion and said outer dielectric portion, at least said outer dielectric portion is disposed corresponding to said second metal surface and covers said second metal surface.   
   
   
       4 . A plasma processing apparatus according to  claim 3  wherein a thickness and a dielectric constant of said outer dielectric portion is set such that said plasma discharge is generated between said electrode in said second movement range and said outer dielectric portion. 
   
   
       5 . A plasma processing apparatus according to  claim 3  wherein a ratio of the thickness to the dielectric constant of said outer dielectric portion is substantially the same as a ratio of a thickness to a dielectric constant of said object. 
   
   
       6 . A plasma processing apparatus according to  claim 3  wherein said electrode has a width astride said outer dielectric portion and said first stage portion in a direction of said relative movement. 
   
   
       7 . A plasma processing apparatus according to  claim 3  wherein said first metal surface is more protruded toward said electrode than said second metal surface; and
 wherein said outer dielectric portion is more protruded toward said electrode than said first metal surface.   
   
   
       8 . A plasma processing apparatus according to  claim 3  wherein a surface of said outer dielectric portion is more protruded toward said electrode than said first metal surface by substantially the same amount as a thickness of said object. 
   
   
       9 . A plasma processing apparatus according to  claim 3  wherein a surface of said inner dielectric portion is flush with said first metal surface. 
   
   
       10 . A plasma processing apparatus according to  claim 3  wherein a thickness of said inner dielectric portion is reduced toward said first stage portion. 
   
   
       11 . A plasma processing apparatus according to  claim 3  wherein a step is formed between said inner dielectric portion and said outer dielectric portion. 
   
   
       12 . An atmospheric-pressure plasma processing apparatus according to  claim 3  wherein said inner dielectric portion and said outer dielectric portion are continuously and integrally formed. 
   
   
       13 . A plasma processing apparatus according to  claim 1  wherein said stage comprises a stage body made of metal;
 wherein a portion located further inward than a peripheral portion in said stage body includes said exposed first metal surface to constitute said first stage portion; and   wherein said peripheral portion of said stage body includes said second metal surface covered with said solid dielectric layer, said peripheral portion of said stage body and said solid dielectric layer constituting said second stage portion.   
   
   
       14 . A plasma processing apparatus according to  claim 1  wherein said electrode is relatively movable within a range including said first movement range, said second movement range and a third movement range located on an opposite side of said second movement range from said first movement range;
 wherein said apparatus further comprises a power supply circuit; and   wherein said power supply circuit starts supplying voltage to said electrode for said plasma discharge when said electrode reaches a predetermined position while said electrode moves from said third movement range toward said first movement range via said second movement range, said predetermined position being located between a position in which said electrode is located astride said second movement range and said third movement range and a position in which said electrode is located immediately before said first movement range.   
   
   
       15 . A plasma processing apparatus according to  claim 14  wherein at said predetermined position, approximately 30 to 70 percent of said electrode is in said second movement range and the rest of said electrode is in said third movement range. 
   
   
       16 . A plasma processing apparatus according to  claim 14  wherein at said predetermined position, approximately 50 percent of said electrode is in said second movement range and the rest of said electrode is in said third movement range. 
   
   
       17 . A plasma processing apparatus according to  claim 14  wherein a width of said electrode in a direction of said relative movement is smaller than a width of said second stage portion in said direction of said relative movement; and
 wherein said predetermined position is a position in which an entirety of said electrode in a width direction is within said second movement range.   
   
   
       18 . A plasma processing apparatus according to  claim 14  wherein said stage further includes a third stage portion having insulation properties and located on an opposite side of said second stage portion from said first stage portion; and
 wherein when said electrode is in said third movement range, said electrode is opposed to said third stage portion.   
   
   
       19 . An atmospheric-pressure plasma processing apparatus for processing a surface of an object to be processed which is mainly composed of a dielectric material by exposing said object to a near atmospheric-pressure plasma discharge, said apparatus comprising:
 a stage including a first stage portion having an exposed first metal surface and a second stage portion having a second metal surface covered with a solid dielectric layer and disposed on an outer peripheral portion of said first stage portion, said object being placed on said first metal surface of said first stage portion such that a peripheral portion of said object is protruded toward said second stage portion;   a first electrode relatively movable with respect to said stage within a range including a first movement range in which said electrode is opposed to said first stage portion, a second movement range in which said electrode is opposed to said second stage portion and a third movement range located on an opposite side of said second movement range from said first movement range;   a second electrode located more to said third movement range side than said first electrode and relatively movable with respect to said stage in unison with said first electrode over a range including said first movement range, said second movement range and said third movement range;   a first power supply circuit that starts supplying voltage to said first electrode for said plasma discharge when said first electrode reaches a first predetermined position during an entrance movement in which said first and second electrodes move from said third movement range toward said first movement range via said second movement range, said first predetermined position being located between a position in which said first electrode is located astride said second movement range and said third movement range and a position in which said first electrode is located immediately before said first movement range; and   a second power supply circuit that starts supplying voltage to said second electrode for said plasma discharge when said second electrode reaches a second predetermined position during said entrance movement, said second predetermined position being located between a position in which said second electrode is located astride said second movement range and said third movement range and a position in which said second electrode is located immediately before said first movement range.