Perpendicular magnetic recording medium and method of manufacturing thereof
View Patent ↗A perpendicular magnetic recording medium is disclosed that is characterized by a lowered noise component and improved thermal stability. The method for making the recording medium includes the serial steps of forming a soft magnetic back-lining layer on a non-magnetic substrate, forming an intermediate layer on the soft magnetic back-lining layer, forming a magnetic recording layer on the intermediate layer, and forming a protective film and then a liquid lubricating layer on the magnetic recording layer. Thermal treatment is executed after the formation of the magnetic recording layer and before the formation of the protective film, or after the formation of the protective film and before the formation of the liquid lubricating layer. The thermal-processing steps are is executed in a vacuum higher than about 0.1 Pa and in a thermal environment within a range from about 200° C. to about 250° C. for a period of less than about 60 seconds.
1. A method of manufacturing a perpendicular magnetic recording medium comprising, in order:
forming a soft magnetic back-lining layer on a non-magnetic substrate;
forming an intermediate layer comprising Ru or Ru-based alloy on said soft magnetic back-lining layer;
forming a magnetic recording layer incorporating a granular structure on said intermediate layer, wherein said granular structure is formed by the dispersion of magnetic grains in a matrix of non-magnetic oxide or non-magnetic nitride;
forming a protective film on said magnetic recording layer; and
forming a liquid lubricating layer on said protective film;
wherein a thermal treatment is performed in an atmosphere ranging in temperature from about 200° C. to about 250° C. for no longer than about 60 seconds under a vacuum higher than about 0.1 Pa either (i) after forming said magnetic recording layer and before forming said protective film, or (ii) after forming said protective film and before the forming said liquid lubricating layer.
2. A method of manufacturing a perpendicular magnetic recording medium according to claim 1 , wherein said thermal treatment is executed for a duration ranging from about one second to about 15 seconds.
3. A method of manufacturing a perpendicular magnetic recording medium according to claim 1 , wherein a seed layer is formed on said soft magnetic back-lining layer by applying a material selected from any type among Ta, Zr, Ni 3 Al, and a Ta-based alloy, and then said intermediate layer is formed after executing said seed-layer forming process.
4. A method of manufacturing a perpendicular magnetic recording medium according to claim 2 , wherein a seed layer is formed on said soft magnetic back-lining layer by applying a material selected from any type among Ta, Zr, Ni 3 Al, and a Ta-based alloy, and then said intermediate layer is formed after executing said seed-layer forming process.
5. A method of manufacturing a perpendicular magnetic recording medium according to claim 3 , wherein an underlayer comprising a material made from soft magnetic permalloy is formed on said seed layer; and then said intermediate layer is formed after the execution of said process for forming said underlayer.
6. A method of manufacturing a perpendicular magnetic recording medium according to claim 4 , wherein an underlayer comprising a material made from soft magnetic permalloy is formed on said seed layer; and then said intermediate layer is formed after the execution of said process for forming said underlayer.
7. A method of manufacturing a perpendicular magnetic recording medium according to claim 1 , wherein an underlayer comprising a material made from soft magnetic permalloy is formed on said soft magnetic back-lining layer, and then said intermediate layer is formed after the execution of said process for forming said underlayer.
8. A method of manufacturing a perpendicular magnetic recording medium according to claim 2 , wherein an underlayer comprising a material made from soft magnetic permalloy is formed on said soft magnetic back-lining layer, and then said intermediate layer is formed after the execution of said process for forming said underlayer.
9. A method of manufacturing a perpendicular magnetic recording medium according to claim 3 , wherein the seed layer is formed using a Ta-based alloy in which a material selected from the group consisting of Cr, Mo, and W is added in an amount of about 1 at % to about 60 at %.
10. A method of manufacturing a perpendicular magnetic recording medium according to claim 4 , wherein the seed layer is formed using a Ta-based alloy in which a material selected from the group consisting of Cr, Mo, and W is added in an amount of about 1 at % to about 60 at %.