Apparatus and method for forming carbon protective layer

Abstract

An apparatus and method for forming a carbon protective layer on a substrate using a plasma CVD method allows a more uniform in-plane distribution of the carbon protective layer thickness. The apparatus includes an annular anode that generates a plasma beam and a disk-shaped shield disposed between the anode and the substrate. The anode, the shield, and the substrate are concentrically arranged so that a straight line connecting the centers of the anode and the substrate is perpendicular to the deposition surface of the substrate where the carbon protective layer is to be formed. The center of the shield is also on the straight line.

1 . An apparatus for forming a carbon protective layer on a substrate by a plasma CVD method, the apparatus comprising:
 an annular-shaped plasma beam generation source configured to be spaced from and disposed parallel to a deposition surface of the substrate, where the carbon protective layer is to be formed; and   a disk-shaped shield spaced from the annular-shaped plasma beam generation source and configured to be positioned between the annular-shaped plasma beam generation source and the substrate,   wherein the disk-shaped shield is concentrically arranged with the annular-shaped plasma beam generation source and the deposition surface of the substrate so that a straight line connecting a center of the annular-shaped plasma beam generation source and a center of the deposition surface of the substrate is perpendicular to the deposition surface of the substrate.   
   
   
       2 . The apparatus for forming a carbon protective layer according to  claim 1 , wherein the disk-shaped shield has a radius equal to an overlap radius A, and a distance x between the disk-shaped shield and the annular-shaped plasma beam generation source satisfies the equation x=[{R/(R+A)}+B]·L, where R is a radius of the annular-shaped plasma beam generation source, L is a distance between the annular-shaped plasma beam generation source and the deposition surface of the substrate, and B is a range of −0.1 or more to 0.1 or less. 
   
   
       3 . A magnetic recording medium having a carbon protective layer formed according to the apparatus of  claim 1 . 
   
   
       4 . A magnetic recording medium having a carbon protective layer formed according to the apparatus of  claim 2 . 
   
   
       5 . A method of forming a carbon protective layer on a substrate by a plasma CVD method, the method comprising the steps of:
 disposing the substrate so that a deposition surface of the substrate, where the carbon protective layer is to be formed, is parallel to and spaced from an annular-shaped plasma beam generation source; and   disposing a disk-shaped shield spaced from the annular plasma beam generation source between the annular-shaped plasma beam generation source and the substrate,   wherein the disk-shaped shield is concentrically arranged with the annular-shaped plasma beam generation source and the deposition surface of the substrate so that a straight line connecting a center of the annular-shaped plasma beam generation source and a center of the deposition surface of the substrate is perpendicular to the deposition surface of the substrate.   
   
   
       6 . The method according to  claim 5 , wherein the disk-shaped shield has a radius equal to an overlap radius A, and a distance x between the disk-shaped shield and the annular-shaped plasma beam generation source satisfies the equation x=[{R/(R+A)}+B]·L, where R is a radius of the annular-shaped plasma beam generation source, L is a distance between the annular-shaped plasma beam generation source and the deposition surface of the substrate, and B is a range of −0.1 or more to 0.1 or less. 
   
   
       7 . A magnetic recording medium having a carbon protective layer formed according to the method of  claim 5 . 
   
   
       8 . A magnetic recording medium having a carbon protective layer formed according to the method of  claim 6 .