Magnetic-disk substrate, magnetic disk, and method for manufacturing magnetic-disk substrate

Patent metadata

Field	Value
Publication number	US-10319403-B2
Application number	US-201615545969-A
Country	US
Kind code	B2
Filing date	Mar 31, 2016
Priority date	Mar 31, 2015
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A magnetic-disk substrate has a pair of main surfaces and arithmetic average roughnesses Ra of the main surfaces are each 0.11 nm or less. Also, in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of the surface unevenness is 25 nm2/protrusion or less. The arithmetic average roughness Ra and the surface unevenness are measured using an atomic force microscope with a probe having a probe tip provided with a carbon nanofiber rod-shaped member.

First claim

The invention claimed is:

1. A magnetic-disk substrate, comprising:
a pair of main surfaces,
an arithmetic average roughness Ra of each of the main surfaces being 0.11 nm or less, and
the arithmetic average roughness Ra being a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member.

2. The magnetic-disk substrate according to claim 1 ,
wherein an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of surface unevenness is 20 nm 2 /protrusion or less.

3. The magnetic-disk substrate according to claim 1 ,
wherein a difference between an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of surface unevenness and an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from the average plane of the surface unevenness is 13 nm 2 /protrusion or less.

4. The magnetic-disk substrate according to claim 1 ,
wherein the carbon nanofiber rod-shaped member provided at the probe tip has a Young's modulus or 100 GPa or less.

5. The magnetic-disk substrate according to claim 1 ,
wherein the carbon nanofiber rod-shaped member is electrically conductive, and one end of the carbon nanofiber rod-shaped member is connected to earth.

6. The magnetic-disk substrate according to claim 1 ,
wherein the arithmetic average roughness Ra or surface unevenness of the main surfaces is obtained based on information on a position of the probe that is obtained by changing the position of the probe in accordance with the surface unevenness of the main surfaces such that the probe oscillates at a constant amplitude.

7. The magnetic-disk substrate according to claim 6 ,
wherein in the measurement performed using the atomic force microscope, the probe is oscillated at a spring constant of 0.1 to 80 N/m and a frequency of 30 to 400 KHz.

8. The magnetic-disk substrate according to claim 1 ,
wherein the substrate is a magnetic-disk substrate for energy-assisted magnetic recording.

9. A magnetic disk,
wherein at least a magnetic film is formed on a surface of the magnetic-disk substrate according to claim 1 .

10. A magnetic-disk substrate, comprising:
a pair of main surfaces,
in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.1 or more from an average plane of the surface unevenness being 25 nm 2 /protrusion or less, and
the surface unevenness of the main surfaces being a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member.

11. The magnetic-disk substrate according to claim 10 ,
wherein the average area of the regions occupied by the plurality of protrusions having a height of 0.1 nm or more from the average plane of the surface unevenness is 20 nm 2 /protrusion or less.

12. The magnetic-disk substrate according to claim 10 ,
wherein a difference between the average area of the regions occupied by the plurality of protrusions having a height of 0.1 nm or more from the average plane of the surface unevenness and an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from the average plane of the surface unevenness is 13 nm 2 /protrusion or less.

13. The magnetic-disk substrate according to claim 10 ,
wherein the carbon nanofiber rod-shaped member provided at the probe tip has a Young's modulus of 100 GPa or less.

14. The magnetic-disk substrate according to claim 10 ,
wherein the carbon nanofiber rod-shaped member is electrically conductive, and one end of the carbon nanofiber rod-shaped member is connected to earth.

15. The magnetic-disk substrate according to claim 10 ,
wherein an arithmetic average roughness Ra of each of the main surfaces or the surface unevenness is obtained based on information on a position of the probe that is obtained by changing the position of the probe in accordance with the surface unevenness of the main surfaces such that the probe oscillates at a constant amplitude.

16. The magnetic-disk substrate according to claim 15 ,
wherein in the measurement performed using the atomic force microscope, the probe is oscillated at a spring constant of 0.1 to 80 N/m and a frequency of 30 to 400 KHz.

Assignees

• Hoya Corp

Inventors

• Itaya Masanobu
• Osakabe Kinobu

Classifications

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• G11B5/8404

  manufacturing base layers · CPC title

• G11B5/82 Primary

  Disk carriers · CPC title

• B82Y10/00

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title

• G11B5/84 Primary

  Processes or apparatus specially adapted for manufacturing record carriers · CPC title