Compositional uniformity control on deposition of magneto-optical disk

The rare earth-transition metal (RE-TM) alloys are widely accepted as the most suitable material for magneto-optical (MO) recording. The magnetic and optical properties of the recording media, hence the read-write-erase characteristics of the disk, are crucially dependent on the composition of the RE-TM films. Tailoring the composition of the films to meet the requirements in various magneto-optical recording applications is, therefore, important. In-line sputtering is the most common method for RE-TM film coating in disk production process. There are two common methods for fabricating sputter target; one is powder-sintering, the other is melt-casting. The former method yields a target composed of mixtures of pure element phases and certain percentage of intermetallic compound phases, the latter method yields a target composed of 100% intermetallic compound phases. The sputtering of RE-TM target often gives nonuniform composition distribution on the disk based on past experiences. This problem motivated us to study the sputtered atom distribution of the targets which were fabricated by different methods.