Protective film mainly composed of a tetrahedral amorphous carbon film and a magnetic recording medium having the protective film

Abstract

A protective film is disclosed that is mainly composed of a tetrahedral amorphous carbon (ta-C film) that is denser than a DLC film formed by a plasma CVD method and containing aggregate particles so reduced as to a necessary and sufficient level, to provide a method of manufacturing such a protective film, and to provide a magnetic recording medium comprising such a protective film. The film is mainly composed of a ta-C film formed by a filtered cathodic arc method using a cathode target of glass state carbon. A magnetic recording medium is disclosed which includes a substrate, a magnetic recording layer, and the protective film mainly composed of a ta-C film.

1 . A protective film for a magnetic recording medium, the protective film being mainly composed of a tetrahedral amorphous carbon film formed by a filtered cathodic arc method using a cathode target of glass state carbon. 
   
   
       2 . The protective film for a magnetic recording medium according to  claim 1 , wherein the protective film has a thickness not greater than 3.0 nm. 
   
   
       3 . The protective film according to  claim 1 , wherein the density of aggregate particles present on the protective film is less than 30/cm 2 . 
   
   
       4 . The protective film for a magnetic recording medium according to  claim 3 , wherein the protective film has a thickness not greater than 3.0 nm. 
   
   
       5 . A method of manufacturing a protective film for a magnetic recording medium, the method comprising steps of:
 generating a plasma that contains carbon ions by arc discharge between an anode and a cathode target composed of glass state carbon;   transporting only carbon ions through a filter part to a film deposition chamber; and   forming a protective film mainly composed of tetrahedral amorphous carbon film by depositing the carbon ions on a target substrate for film deposition disposed in the film deposition chamber.   
   
   
       6 . A magnetic recording medium comprising at least a substrate, a magnetic recording layer, and a protective film formed on the magnetic recording layer, wherein the protective film is the protective film for a magnetic recording medium as defined by  claim 1 . 
   
   
       7 . A magnetic recording medium comprising at least a substrate, a magnetic recording layer, and a protective film formed on the magnetic recording layer, wherein the protective film is the protective film for a magnetic recording medium as defined by  claim 3 .