Plasma polish for magnetic recording media
Fabrication methods for magnetic recording media that use a plasma polish are disclosed. For one exemplary method, a film of a magnetic recording medium is deposited, and a top surface of the film is polished utilizing a plasma formed by a noble gas to smoothen the top surface of the film. A subsequent layer is then deposited onto the polished top surface of the film. A top surface of the subsequent layer has a reduced roughness by being deposited on the polished top surface of the film.
1. A method of fabricating a magnetic recording disk, the method comprising:
depositing a cap layer that is exchange coupled to a magnetic recording layer of the magnetic recording disk;
polishing a top surface of the cap layer utilizing a plasma formed by a noble gas to smoothen the top surface of the cap layer; and
depositing a protective carbon overcoat on the polished top surface of the cap layer to a thickness of less than 22 angstroms, wherein the protective carbon overcoat has a Cobalt extraction count of less than 0.8 nanograms.
2. The method of claim 1 wherein polishing the top surface of the cap layer further comprises:
applying a negative bias voltage to the cap layer during the polish process which generates an electric field accelerating positive ions toward the cap layer.
3. The method of claim 2 wherein the bias voltage is a Direct Current (DC) voltage between −400 and −600 volts relative to a sputter shield.
4. The method of claim 1 wherein polishing the top surface of the cap layer is carried out in a DC magnetron station.
5. The method of claim 1 wherein the noble gas comprises one or more of Argon, Krypton, and Neon.
6. The method of claim 1 wherein polishing the top surface of the cap layer reduces a roughness of the protective carbon overcoat to 5.1 angstroms.
7. The method of claim 1 wherein polishing the top surface of the cap layer reduces an interfacial roughness between the cap layer and the protective carbon overcoat to 5.1 angstroms.
8. The method of claim 1 wherein polishing the top surface of the cap layer further comprises:
applying a negative bias voltage to the cap layer; and
supplying a flow of noble gas proximate to the magnetic recording disk.
9. The method of claim 8 wherein a pressure of the noble gas proximate to the magnetic recording disk is 30 millitorr.
10. The method of claim 9 wherein a flow rate of the noble gas is higher than 40 Standard Cubic Centimeter per Minute (SCCM).