The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 16, 1996
Filed:
Sep. 01, 1994
Tsutomu T Yamashita, Milpitas, CA (US);
Kyou H Lee, San Jose, CA (US);
Rajiv Y Ranjan, San Jose, CA (US);
Yuri Trachuk, San Jose, CA (US);
Komag, Incorporated, Milpitas, CA (US);
Abstract
A carbon film for protecting a magnetic disk is sputtered by a DC magnetron sputtering method, with the addition of superimposed AC power on the DC power applied to the carbon target. When the carbon film is sputtered for extended period in a production sputtering machine, nodular growth occurs over the sputtering surface of the carbon target. Such nodules are variously called 'warts' or 'mushrooms' in the industry and they are detrimental to the productivity of the sputtering machine. The size and quantity of the nodules over the target surface increase as the target is sputtered longer, and because these region do not contribute to sputtering, the efficiency of the target decreases. As sputter efficiency decreases, power input must be increased to the target to make up for the loss in the effective sputtering area of the target. Eventually, the power input must be increased to a point where arcing occurs continuously and sputtering cannot be continued. By superimposing AC power onto the DC power applied to the target, virtually all arcing on the carbon target is eliminated, thereby significantly reducing the nodular growth and extending the use of the target.