Method and device for coating substrates

Abstract

The device for simultaneous multi-sided coating of a substrate, especially a lens, by microwave plasma chemical vapor deposition has a reaction chamber with microwave windows and microwave guides with microwave launch sites for guiding microwaves into the reaction chamber through the windows; dielectric tuning elements at the microwave launch sites to influence the microwave field distribution and at least one substrate holder arranged so that surfaces to be coated are oriented perpendicularly to plasma propagation directions. The respective shapes of the dielectric tuning elements are adapted to corresponding shapes of the surfaces, so that inhomogeneities in plasma distributions in the plasmas formed in the reaction chamber are corrected and coatings formed on the surfaces have a uniform thickness. Coated surfaces on opposite sides of a lens have a uniformity of ±1%.

1 - 15 . (canceled)  
   
   
       16 . A device for simultaneous multi-sided coating of substrates by microwave plasma chemical vapor deposition, comprising 
 a reaction chamber provided with at least one gas inlet;    at least two microwave windows provided in said reaction chamber;    at least two microwave guides with microwave launch sites for guiding microwaves into the reaction chamber through the microwave windows;    dielectric tuning elements arranged in the vicinity of the microwave launch sites and influencing a microwave field distribution in said reaction chamber; and    at least one substrate holder arranged in said reaction chamber to hold a substrate so that respective substrate surfaces to be coated are oriented perpendicularly to propagation directions of corresponding coating plasmas generated in said reaction chamber for coating the respective substrate surfaces;    wherein corresponding distances between the respective substrate surfaces to be coated and the microwave launch sites are each greater than a penetration depth of the microwaves in the coating plasmas; and    wherein respective shapes of said dielectric tuning elements are adapted to corresponding shapes of said substrate surfaces to be coated, so that inhomogeneities in plasma distributions in said coating plasmas are corrected and said substrate surfaces are simultaneously coated with coatings of uniform thickness.    
   
   
       17 . A device as defined in  claim 16 , wherein said dielectric tuning elements are each composed of a material selected from the group consisting of quartz and polytetrafluoroethylene.  
   
   
       18 . A device as defined in  claim 16 , wherein said dielectric tuning elements are arranged on atmospheric sides of said microwave launch sites.  
   
   
       19 . A device as defined in  claim 18 , wherein said dielectric tuning elements are arranged on said microwave windows.  
   
   
       20 . A device as defined in  claim 18 , wherein said dielectric tuning elements have outer contours corresponding to inner contours of the microwave guides.  
   
   
       21 . A device as defined in  claim 18 , wherein said dielectric tuning elements are each selected from the group consisting of rings, disks, cones and pyramids.  
   
   
       22 . A device as defined in  claim 22;  wherein said at least one gas inlet is on said at least one substrate holder.  
   
   
       23 . A device as defined in  claim 16 , wherein a respective distance between said at least one substrate holder and each of said microwave windows is between 5 and 80 mm.  
   
   
       24 . The device as defined in  claim 16 , wherein said reaction chamber has two of said microwave windows arranged on opposite sides of said reaction chamber and said microwave waveguides extend on said opposite sides of said reaction chamber from said microwave windows.  
   
   
       25 . The device as defined in  claim 24 , wherein said dielectric tuning elements are arranged on atmospheric sides of the microwave launch sites, said dielectric tuning elements are arranged on said microwave windows and said dielectric tuning elements have outer contours corresponding to inner contours of the microwave guides.  
   
   
       26 . The device as defined in  claim 16  or  24 , wherein said substrate is a lens and said substrate surfaces to be coated are on opposite sides of said lens, one of said substrate surfaces to be coated is a concave surface, said concave surface is associated with first and second dielectric tuning elements, said first and second dielectric tuning elements consist of a disk and a ring, said ring rests on said disk on an atmospheric side of an associated one of said microwave launch sites and said disk and said ring have respective outer diameters each corresponding to an inner diameter of a waveguide through which said microwaves pass.  
   
   
       27 . The device as defined in  claim 16  or  24 , wherein said substrate is a lens and said substrate surfaces to be coated are on opposite sides of said lens, one of said substrate surfaces to be coated is a convex surface, said convex surface is associated with first and second dielectric tuning elements, said first and second dielectric tuning elements consist of two disks, said disks rest against each other on an atmospheric side of an associated one of said microwave launch sites, one of said disks has an outer diameter corresponding to an inner diameter of a waveguide through which said microwaves pass and another of said disks has an outer diameter smaller than said inner diameter of said waveguide.