Method and apparatus making magnetic recording disk

• US 4,894,133 A
• Filed: 06/22/1988
• Issued: 01/16/1990
• Est. Priority Date: 11/12/1985
• Status: Expired due to Fees

• Current Assignee: Magnetic Media Development LLC
• Original Assignee: Virgle L. Hedgcoth
• Inventors: Hedgcoth, Virgle L.
• Primary Examiner(s): Nguyen, Nam X.
• Application Number:
  US07/210,119
• Time in Patent Office: 573 Days
• Field of Search: 204/164, 204/298, 204/192.15, 204/192.16, 204/192.2, 204/192.22, 204/298, 204/298 ME, 204/298 PM, 204/298 SC, 204/298 SM, 204/298 MC , 204/298 MD, 414/217, 414/222, 198/345, 51/281 R, 51/281 SF, 51/135 R
• US Class Current: 204/192.15
• CPC Class Codes: G11B 5/64 comprising only the magnetic material without bonding agent
• CPC Class Codes: G11B 5/727 Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon
• CPC Class Codes: G11B 5/737 Physical structure of underlayer, e.g. texture
• CPC Class Codes: G11B 5/73919 Aluminium or titanium elemental or alloy substrates
• CPC Class Codes: G11B 5/851 Coating a support with a magnetic layer by sputtering
• CPC Class Codes: Y10S 428/928 Magnetic property
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape
• CPC Class Codes: Y10T 428/12472 Microscopic interfacial wave or roughness
• CPC Class Codes: Y10T 428/12625 Free carbon containing component
• CPC Class Codes: Y10T 428/1275 Next to Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12854 Next to Co-, Fe-, or Ni-base component

Abstract

A sputtering production assembly for producing a magnetic thin-film memory disk and a method of coating the memory disk is provided. The magnetic disk substrates are preliminarily abraded to provide a uniform series of physical circumferential texturing to encourage a circular anisotropic orientation of crystal growth during the subsequent sputtering steps. A nucleating layer is deposited under controlled conditions, and subsequently a thin-film magnetic layer is deposit with a circular anisotropic orientation of crystal growth. Finaly, a thin-film protective coating is disposed on the magnetic layer.

Claims

1. A direct current planar magnetron sputtering source process of producing magnetic thin film memory disks with coatings on both sides of the disk, comprising the steps of:

providing substrates;

physically abrading the substrates to provide a uniform series of concentric grooves having a radial roughness factor within the range of 50 to 500 angstroms to encourage a circular anisotropic orientation of crystal growth during subsequent sputtering steps;

providing means for unidirectional transportation of substrates through a sequential series of continual concurrent sputtering processing steps in a deposition chamber having a series of partition walls with apertures for dividing the deposition chamber into separate sputtering chambers at a common pressure level including a carrier for supporting the substrates in vertical positions;

reducing the initial ambient pressure to a reduced common pressure level within a pressure range to enable a sputtering operation while eliminating atmospheric contaminants;

providing a first pair of elongated direct current planar magnetron sputtering sources of a nucleating layer, one on either side of the path of travel of the vertical substrates;

providing a gas in a plasma state of sufficient density to ensure acceptable amplitude modulation characteristics in the finished disks;

bombarding the first pair of nucleating sources with ions from the plasma gas to uniformly deposit a nucleating layer on both sides of the substrate to enable a predetermined epitaxial growth of a subsequent magnetic layer while moving the substrates continually past the sources;

providing a second pair of elongated direct current planar magnetron sources of a magnetic layer on either side of the path of travel of the substrate at a position separate and downstream of the first pair of nucleating sources;

bombarding the second pair of magnetron sources during the same time period as the first nucleating sources are being bombarded to form a magnetic layer whereby a continual coating process on both sides of a substrate can be performed sequentially as substrates are transported through the sputtering process steps;

providing a third pair of elongated direct current planar magnetron sources of a protective layer on either side of the path of travel of the substrate at a position separate and downstream of the second pair of magnetic sources;

bombarding the third pair of protective coating sources to form a protective coating during the same time period as the second magnetron sources are being bombarded to provide a third state of a continual coating process as the substrates are transported through the sputtering process steps; and

removing the coated memory disk without effecting the sputtering operation pressure range.

2. The invention of claim 1 wherein the means for unidirectional transportation includes a constant velocity of movement of the substrate through each series of the sputtering process steps.

3. The invention of claim 2 wherein the velocity is within the range of 1 to 10 mm/sec.

4. The invention of claim 1 wherein the substrate is selected from a material of nickel plated aluminum, aluminum, plastic, and glass.

5. The invention of claim 1 wherein the nucleating layer is selected from chromium and titanium.

6. The invention of claim 1 wherein the magnetic layer is selected from one of cobalt, a cobalt/nickel alloy, a cobalt/chromium alloy and a cobalt/vanadium alloy.

7. The invention of claim 1 wherein the protective coating is selected from one of carbon, titanium carbide, boron carbide and tungsten carbide.

8. The invention of claim 1 wherein the plasma gas is selected from one of argon and krypton.

9. The invention of claim 1 wherein the nucleating layer source is chromium, the magnetic layer source is a cobalt/nickel alloy and the protective coating is carbon.

10. The invention of claim 9 wherein the purity of the source layer of the respective nucleating, magnetic and protective layer is at least 99.99% pure.

11. The invention of claim 1 further including providing a plasma gas within the pressure range of 1×

10^-2 torr to 7.5×

10^-2 torr to provide collisional scattering of sputtered atoms to avoid low angle of incidence of film nucleation.

12. The invention of claim 1 further including providing a temperature range of 75°

C. to 250°

C. during the sputtering processing steps.

13. The invention of claim 1 wherein a protective coating of carbon having a layer thickness within the range of 200 to 800 angstrom is provided.

14. The invention of claim 1 wherein the means for unidirectional transportation aligns the substrate in a vertical plane relative to a support surface.

15. The invention of claim 1 wherein the layer thickness of the nucleating layer of chromium is within the range of 1000 to 5000 angstroms.

16. The invention of claim 1 wherein the layer thickness of the magnetic layer of cobalt/nickel alloy is within the range of 200 to 1500 angstroms.

17. The invention of claim 1 wherein the magnetic disk switching field distribution resulting from the process steps is less than 0.20.

18. The invention of claim 1 wherein the magnetic disk once around track signal average amplitude modulation is less than plus or minus 15 percent.

19. The invention of claim 1 further including pre-heating the substrate to approximately 100°

C.

20. The invention of claim 1 further including providing a plasma gas within the pressure range of 2×

10^-2 torr to 4×

10^-2 torr to provide collisional scattering of sputtered atoms to avoid low angle of incidence of film nucleation.

21. The invention of claim 20 further including providing a temperature of approximately 200°

C. during the sputtering processing steps.

22. The invention of claim 21 wherein the preferred radial roughness factor is approximately 200 angstroms.

23. The invention of claim 1 wherein the substrate to source distances are within 2 to 4 inches for each source in the sputtering process steps.

24. A direct current planar magnetron sputtering source production assembly for producing magnetic thin film memory disks with coatings on both sides of the disk, comprising:

means for a constant velocity unidirectional transportation of a plurality of vertically aligned substrates through a sequential series of concurrent sputtering processing steps including a deposition chamber having a series of partition walls with apertures for dividing the deposition chamber into separate sputtering chambers at a common pressure level;

means for reducing the initial ambient pressure to a common reduced pressure level within a pressure range to enable a sputtering operation;

means for providing a gas in a plasma step within the approximate pressure range of 2×

10^-2 torr to 4×

10^-2 torr to each separate sputtering chamber;

means for physically abrading the substrates to provide a uniform series of concentric grooves on each substrate having a radial roughness factor within the range of 50 to 500 angstroms to encourage a circular anisotropic orientation of crystal growth during subsequent sputtering;

means for providing a thin film of nucleating layer on a substrate including a first pair of elongated direct current planar magnetron sputtering sources of a nucleating layer material, one on either side of the path of travel of the substrate and means for bombarding the first pair of nucleating sources with ions from the plasma gas to uniformly deposit a nucleating layer on both sides of the substrate to enable a predetermined epitaxial growth of a subsequent magnetic layer;

means for providing a thin film magnetic layer on the nucleating layer including a second pair of elongated direct current planar magnetron sources of a magnetic layer on either side of the path of travel of the substrate at a position separate and downstream of the first pair of nucleating sources and means for bombarding the second pair of magentron sources during the same time period as the first nucleating sources are being bombarded whereby a continual coating process on both sides of a substrate can be performed sequentially as substrates are transported through the sputtering process steps;

means for providing a thin film protective layer on the magnetic layer including a third pair of elongated direct current planar magnetron sources of a protective layer on either side of the path of travel of the substrate at a position separate and downstream of the second pair of magnetic sources; and

means for bombarding the third pair of protective coating sources during the same time period as the second magentron sources are being bombarded to provide a third stage of a continual coating process as the substrates are transported through the sputtering process steps so that the bombarding of the sources is constant during the transportation of the disks to ensure uniform deposition layers from disk to disk.

25. The invention of claim 24 wherein the means for unidirectional transportation aligns the substrate in a vertical plane relative to a support surface.

26. The invention of claim 24 further including means for providing a temperature range of 75°

C. to 250°

C. during the sputtering processing steps.

27. The invention of claim 24 wherein the radial roughness factor is approximately 200 angstroms.