Dependence of properties of amorphous Co-Zr films on plasma state in sputtering

Amorphous Co-Zr alloy films with excellent soft magnetism have been prepared by the toroidal plasma (TP) sputtering method. The DC discharge and sputtering characteristics were investigated by applying an additional magnetic field by means of a solenoid coil in order to change the plasma state in sputtering. The applied voltage, discharge current, film thickness, and film composition were found to depend rather strongly on the plasma state. The appropriate magnetic flux could suppress the excessive bombardment of the substrate by γ-electrons. Amorphous Co-Zr films with excellent soft magnetic properties (e.g. 4 πMs of about 16 kG and H_c of about 0.3 Oe) were deposited on a substrate bombardment by coherent ions from a toroidal plasma. For ions of an appropriate energy, the bombardment improves the soft magnetic properties. This method may be useful for depositing Co-Zr films with high permeability at radio frequency