Plasma treatment apparatus and method of manufacturing optical parts using the same

Abstract

A plasma treatment apparatus for treating a surface of an object of treatment comprises a pressure reducible container, a gas supply means for supplying gas into the container for plasma excitation, an evacuation means for evacuating the inside of the container and a microwave supply means for supplying a microwave into the container. The surface of said microwave supply means located opposite to said object of treatment is a non-planar surface. A film coat showing an excellent intra-surface uniformity and practically free from pin holes and local defects can be formed by means of such an apparatus.

What is claimed is:  
     
         1 . A plasma treatment apparatus for treating a surface of an object of treatment, comprising a container, a gas supply means for supplying gas into the container for plasma excitation, an evacuation means for evacuating the inside of said container, and a microwave supply means for supplying a microwave into said container, the surface of said microwave supply means located opposite to said object of treatment being a non-planar surface having a contour corresponding to that of the surface to be treated of said object of treatment and said non-planar surface being formed of a microwave-transmitting dielectric.  
     
     
         2 . A plasma treatment apparatus according to  claim 1 , wherein gas is supplied through a plurality of openings arranged on said non-planar surface.  
     
     
         3 . A plasma treatment apparatus according to  claim 1 , wherein said microwave supply means has an antenna made of a flat plate of a conductor and having a number of slots.  
     
     
         4 . A plasma treatment apparatus according to  claim 1 , wherein said non-planar surface is a convex or concave spherical surface formed on the microwave-transmitting dielectric.  
     
     
         5 . A method of manufacturing an optical part comprising a step of treating a concave or convex surface of the optical part by means of a plasma treatment apparatus according to  claim 1 .  
     
     
         6 . A plasma treatment apparatus for treating a surface of an object of treatment, comprising: 
 a container;    a gas supply means for supplying gas into the container for plasma excitation; and    an evacuation means for evacuating the inside of said container,    a part of the walls of said container being made of a dielectric plate of a material adapted to transmit microwaves,    said dielectric plate having a convex or concave spherical surface with a predetermined radius of curvature,    an antenna for emitting a microwave and an electrode adapted to hold the object of treatment being arranged respectively at the outside and at the inside of said container to sandwich the dielectric plate.    
     
     
         7 . A plasma treatment apparatus according to  claim 1  or  6 , wherein the dielectric plate has a shower-head-like profile provided with a plurality of gas supply holes for evenly supplying gas to the surface of said object of treatment.  
     
     
         8 . A plasma treatment apparatus according to  claim 6 , wherein the radius of curvature and the radius of aperture of said dielectric plate are variable.  
     
     
         9 . A plasma treatment apparatus according to  claim 1  or  6 , wherein the distance between the inner surface of said dielectric plate and the surface to be treated of said object of treatment is between 10 mm and 50 mm.  
     
     
         10 . A plasma treatment apparatus according to  claim 1  or  6 , wherein the relative density difference of the plasma in said surface to be treated is suppressed to less than about 20%.  
     
     
         11 . A plasma treatment apparatus according to  claim 6 , wherein the variations in the plasma density due to the variations in the thickness of said dielectric plate can be corrected by making at least the size, the profile or the number of the slots formed in said antenna to show a distribution pattern.  
     
     
         12 . A plasma treatment apparatus according to  claim 6 , wherein said object of treatment held by a support member is provided with a rotary mechanism.  
     
     
         13 . A plasma treatment apparatus according to  claim 6 , wherein said non-planar surface is a stepped surface obtained by forming coaxial steps.  
     
     
         14 . A plasma treatment apparatus according to  claim 6 , wherein said gas supply means has a stepped shower-head-like profile.  
     
     
         15 . A plasma treatment apparatus according to  claim 6 , wherein the main body of said antenna has a spherical or stepped profile.  
     
     
         16 . A plasma treatment apparatus according to  claim 6 , wherein said antenna having a spherical or stepped profile is arranged within said container.  
     
     
         17 . A plasma treatment apparatus according to  claim 6 , wherein a non-planar surface is formed by using a plurality of such antennas.  
     
     
         18 . A surface treatment method for treating the surface of an object of treatment by means of an apparatus according to  claim 1 .  
     
     
         19 . A surface treatment method according to  claim 18 , wherein said surface treatment consists in forming a thin film.  
     
     
         20 . A method of manufacturing an optical part by using a surface treatment method according to  claim 18  and forming an anti-reflection or reflection-boosting thin film on an object of treatment made of silicon oxide or calcium fluoride.  
     
     
         21 . A plasma treatment apparatus for treating a surface of an object of treatment, comprising a container, a gas supply means for supplying gas into the container for plasma excitation, an evacuation means for evacuating the inside of said container, and a microwave supply means for supplying a microwave into said container, said microwave supply means having a plurality of microwave emitting members and its surface located opposite to the object of treatment being directed in a predetermined direction relative to the surface to be treated of said object of treatment.  
     
     
         22 . A plasma treatment apparatus according to  claim 21 , wherein each of said microwave emitting members include a conductor flat plate antenna having a number of slots.  
     
     
         23 . A method of manufacturing an optical part comprising a step of forming a film coat on an optical part by using an apparatus according to  claim 21 .  
     
     
         24 . A plasma treatment apparatus for treating a surface of an object of treatment, comprising a container, a gas supply means for supplying gas into the container for plasma excitation, an evacuation means for evacuating the inside of said container, and a microwave supply means for supplying a microwave into said container, the surface of said microwave supply means located opposite to said object of treatment being a non-planar surface having a contour corresponding to that of the surface to be treated of said object of treatment.  
     
     
         25 . A plasma treatment apparatus according to  claim 24 , wherein said gas supply means includes an antenna of a conductor member having a spherical surface and slots.  
     
     
         26 . A plasma treatment apparatus according to  claim 25 , wherein the gas blow-in port of said gas supply means is arranged at an end of the antenna made of a conductor member having slots.  
     
     
         27 . A plasma treatment apparatus according to  claim 24 , wherein the distance between the inner surface of said microwave supply means and the surface to be treated of said object of treatment is between 10 mm and 50 mm.  
     
     
         28 . A method of manufacturing an optical part comprising a step of forming a film coat on an optical part by using an apparatus according to claim  24 .