Improved ion beam deposition system with RF sputter-type ion source

A newly developed RF sputter-type ion source has been introduced into our ion beam deposition (IBD) system for high purity Fe film formation, Vacuum environment during deposition has been much improved compared with our previous IBD system, in which a conventional CCl4 method was employed to produce Fe+ ions in a microwave ion source, With no use of CCl4 gas, an inert argon background has been achieved. The ion source is composed of an RF (13.56 MHz) Cu coil and an Fe sputter target located inside, An Ar discharge was generated at an RF power of 100-300 W and a negative DC bias voltage of 500-1000 V was applied to the Fe target. The tip of the target was heated almost up to the melting temperature and simultaneous sputtering and evaporation took place. Major ion species extracted were Ar+ and Fe+ ions, With an increase in the DC bias voltage up to 1 kV, a relative ratio of Fe+ to Ar+ ion intensities became one order larger. This efficient Fe+ ion production is thought to be due to a Penning ionization effect of metastable Ar* atoms. It is expected to form extremely high purity Fe films, in contrast to our former Fe films which contained C and CI as impurities.