# US 4,399,013 A · Method of producing a magnetic recording medium

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- Number: US 4,399,013 A
- Document ID: US4399013A
- Status: Granted
- Kind: A
- Application number: 06/240,369
- Filed: 1981-03-04
- Granted: 1983-08-16
- Earliest claimed: 1980-03-07
- Assignees: Matsushita Electric Industrial Co., Ltd.
- Inventors: Ryuji Sugita; Toshiaki Kunieda
- Web page: https://patentgrep.com/patent/US4399013A

## CPC

- G11B 5/656: {containing Co (containing inorganic, non-oxide compounds of Si, N, P, B, H or C G11B5/657; containing oxygen G11B5/658)}
- G11B 5/851: Coating a support with a magnetic layer by sputtering
- H01F 41/20: by evaporation
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

There is provided a method of producing a magnetic recording medium having a magnetic layer composed mostly of Co and Cr. The method is characterized by vacuum vapor deposition of components which are to form the magnetic layer under conditions where atoms of the evaporated components are in the discharge state.

## Claims

### Claim 1

A method of producing a perpendicular magnetic recording medium, including a step of forming a magnetic layer as a thin film composed predominantly of cobalt and chromium on a substrate, wherein said thin film is formed by vacuum vapor deposition under conditions which comprise:
producing a vapor composed predominantly of cobalt and chromium from an evaporation source, causing electrons to be produced in proximity to said evaporation source and causing these electrons to reach the substrate surface in an amount sufficient to cause the atoms of vaporized film-forming material at or near the substrate to be in the discharge state.

### Claim 2 (depends on 1)

The method of producing a magnetic recording medium as claimed in claim 1, wherein at least one evaporation source for at least one component of said film-forming material is an evaporation source associated with an electron gun and the electric power supplied to said electron gun during the formation of said magnetic layer is sufficiently large to cause the atoms of vaporized material to be in the discharge state.

### Claim 3 (depends on 2)

The method for producing a magnetic recording medium as claim in claim 2, wherein an evaporation source is used which is insulated from the environment except for action of said associated electron gun.

### Claim 4 (depends on 1)

The method of producing a magnetic recording medium as claimed in claim 1, wherein at least one evaporation source for at least one component of said film-forming material is an evaporation source associated with an electron gun and said vacuum vapor deposition is carried out with said substrate or the vicinity of said substrate being maintained at a positive potential with respect to said evaporation source.

### Claim 5 (depends on 1)

The method of producing a magnetic recording medium as claimed in claim 1, wherein said vacuum vapor deposition is carried out by applying a high frequency voltage to a high frequency electrode positioned between said substrate and an evaporation source for film-forming material to thereby ionize atoms of said film-forming material, with said substrate or the vicinity of said substrate being maintained at a positive potential with respect to said evaporation source.