METHOD OF PRODUCING PERPENDICULAR MAGNETIC RECORDING MEDIUM
A method of producing a perpendicular magnetic recording medium with a magnetic recording layer formed from ferromagnetic crystal grains and oxide-including non-magnetic crystal grain boundaries and provided on a non-magnetic substrate. The method is initiated by forming the magnetic recording layer by a reactive sputtering method using rare gas containing 2% by volume to 10% by volume (both inclusively) of oxygen gas at an initial stage of film formation. The method continues by successively forming the magnetic recording layer by reactive sputtering while reducing the concentration of the oxygen gas. The method may further include forming an undercoat layer of Ru or a Ru-alloy under the magnetic recording layer. In this manner, a granular magnetic layer having high characteristic coercive force (Hc) can be formed, while reducing the amount of expensive Pt or Ru required.
1 . A method of producing a perpendicular magnetic recording medium on a non-magnetic substrate, comprising:
initiating a reactive sputtering method for the formation of a magnetic recording layer on the non-magnetic substrate, wherein:
during an initial stage the reactive sputtering method comprises sputtering using a gas combination of a rare gas and oxygen gas, the gas combination comprising 2% to 10% by volume inclusively of the oxygen gas;
and
completing the formation of the magnetic recording layer by continuing the reactive sputtering method using the gas combination while reducing the concentration of the oxygen gas as a percentage by volume of the gas combination;
whereby the magnetic recording layer formed on the non-magnetic substrate comprises ferromagnetic crystal grains and oxide-including non-magnetic crystal grain boundaries.
2 . The method of producing a perpendicular magnetic recoding medium of claim 1 , wherein the rare gas comprises argon gas.
3 . The method of producing a perpendicular magnetic recoding medium of claim 1 , further comprising forming an undercoat layer of Ruthenium (Ru) or a Ru-containing alloy immediately under the magnetic recording layer.
4 . The method of producing a perpendicular magnetic recording medium of claim 1 , further comprising forming a soft magnetic backing layer between the non-magnetic substrate and the magnetic recording layer.
5 . The method of producing a perpendicular magnetic recording medium of claim 1 , wherein the initial stage of the sputtering method comprises a stage where between 10% and 60% inclusive of the final film thickness of the magnetic recording layer is formed.
6 . The method of producing a perpendicular magnetic recording medium of claim 5 , wherein:
the magnetic recording layer is formed from laminated magnetic layers; and
the final film thickness is the sum of the respective film thicknesses of the laminated magnetic layers.
7 . The method of producing a perpendicular magnetic recording medium of claim 1 , wherein the magnetic recording layer comprises at least one of a Cobalt-Platinum (CoPt) based alloy or a Cobalt-Chromium-Platinum (CoCrPt) based alloy.
8 . The method of producing a perpendicular magnetic recording medium of claim 7 , wherein the magnetic recording layer further comprises at least one of Tantalum (Ta), Boron (B), Niobium (Nb), Silver (Ag), Molybdenum (Mo), Tungsten (W), Palladium (Pd) or Copper (Cu).
9 . A perpendicular magnetic recording medium, comprising:
a non-magnetic substrate; and
a magnetic recording layer produced on the non-magnetic substrate, wherein the magnetic recording layer is produced by a process of initiating a reactive sputtering method for the formation of the magnetic recording layer on the non-magnetic substrate, wherein:
during an initial stage the reactive sputtering method comprises sputtering using a gas combination of a rare gas and oxygen gas, the gas combination comprising 2% to 10% by volume inclusively of the oxygen gas;
and
completing the formation of the magnetic recording layer by continuing the reactive sputtering method using the gas combination while reducing the concentration of the oxygen gas as a percentage by volume of the gas combination;
whereby the magnetic recording layer formed on the non-magnetic substrate comprises ferromagnetic crystal grains and oxide-including non-magnetic crystal grain boundaries.
10 . The perpendicular magnetic recording medium of claim 9 , further comprising an undercoat layer of Ruthenium (Ru) or a Ru-containing alloy immediately under the magnetic recording layer.
11 . The perpendicular magnetic recording medium of claim 9 , further comprising a soft magnetic backing layer between the non-magnetic substrate and the magnetic recording layer.
12 . The perpendicular magnetic recording medium of claim 9 , wherein the initial stage of the sputtering method forming the magnetic recording layer comprises a stage where between 10% and 60% inclusive of the final film thickness of the magnetic recording layer is formed.
13 . The perpendicular magnetic recording medium of claim 12 , wherein:
the magnetic recording layer comprises laminated magnetic layers; and
the final film thickness is the sum of the respective film thicknesses of the laminated magnetic layers.
14 . The perpendicular magnetic recording medium of claim 9 , wherein the magnetic recording layer comprises at least one of a Cobalt-Platinum (CoPt) based alloy or a Cobalt-Chromium-Platinum (CoCrPt) based alloy.
15 . The magnetic recording medium of claim 14 , wherein the magnetic recording layer further comprises at least one of Tantalum (Ta), Boron (B), Niobium (Nb), Silver (Ag), Molybdenum (Mo), Tungsten (W), Palladium (Pd) or Copper (Cu).