Tilt-Target Magnetron Sputter for Deposition of Magnetooptical Disk

A 3.5-inch magnetooptical disk is made by tilting the TbFeCo target in a DC circular magnetron sputtering process. The composition of the recording layer is controlled by using the Tb-rich deposition area. The optimal tilt angle of our target for uniform radial composition distribution on the disk is found to be about 15°. A model was proposed to explain the observed Tb, Fe and Co content variation with the tilt angle of the target. The dynamic read/write test also showed that good carrier to noise ratio (CNR) was obtained at this angle. A new deposition process for magnetooptical (M-O) disk based on the tilt target method is proposed; it has the merits of enabling simultaneous deposition of multiple disks. The CNR of the disk made at 15° tilt angle is 53 dB.