Planar magnetron sputtering discharge enhanced with radio frequency or microwave magnetoactive plasma

The de discharge of an unbalanced planar magnetron was enhanced by a rf or microwave plasma generated by a helical antenna. An array of permanent magnets around the discharge chamber was used for the plasma confinement. The discharge current-voltage characteristics, substrate ion current densities i(s) and ionized fraction of the flux of sputtered metal atoms are reported. The substrate ion current density i(s) was found to depend strongly on the type and orientation of the permanent magnets with order-of-magnitude differences between different configurations. The rf or microwave enhancement of the sputtering discharge resulted in (i) increased substrate ion current densities i(s) up to 7 mA/cm(2) even for low pressures <0.1 Pa, (ii) control of i(s) independently on the discharge current, (iii) sputtering at low pressures down to 7 x 10(-3) Pa, (iv) well controlled de discharge at small cathode voltages, i.e., at small sputtering rates. These features enable a low pressure sputter deposition of thin films grown under an intensive ion assistance. (C) 1997 American Vacuum Society.