High-recording-density magnetic disk

PURPOSE: To obtain a magnetic disk of high reliability and high recording density with corrosion resistance and resistance to wear both improved by providing as a protective film a thin film of a compound of a silicon nitride on a ferromagnetic metal film. CONSTITUTION: On substrate 1 of a magnetic disk used for a CSS (contact start stop) system magnetic disk unit, base plating film 2 is formed and then ferromagnetic metal film 3 is provided. Next, compound film 4 of silicon nitride is formed as a protective film in a reaction plasma vapor-depositing method. Here, a compound of silicon nitride expressed by Si(2W4)N(3W5)O(0W1) is specially recommended. As original gas, SiH 4 and NH 3 are used and a parallel electrode type plasma CVD device, etc., are used to form protective film 4. In this way, a magnetic disk can be obtained which has resistance-to-wear of more than 40,000 in the number of times of CSS and sufficient corrosion resistance. COPYRIGHT: (C)1980,JPO&Japio