Magnetron with gas injection through hollow cathodes machined in sputtered target

This article reports on a magnetron equipped with a target with holes. The holes machined in sputtered target can sustain hollow cathode discharges and/or inject the sputtering gas directly inside the magnetron discharge. This magnetron operates on the same principle as a gas-jet. It is shown that the size and number of holes can efficiently control I–V characteristics of the magnetron. The holes of large (≥2 mm) diameter can sustain hollow cathode discharges, which intensify the magnetron discharge. On the contrary, the holes of small (≤1 mm) diameter influences the I–V characteristics much less and allow: (i) to introduce the sputtering gas directly inside the discharge; and (ii) to compensate a gas density reduction in front of target when the magnetron is operated at high (≥100 W/cm2) target power densities. Special attention is devoted to reactive sputtering. There is great difference in the deposition rate aD of films in the case when the sputtering gas is fed to the chamber or to the discharge through the holes. It is shown that for the gas feed to chamber, aD of the nitride films, sputtered from target with four holes of diameter 2 mm, is equal to that of pure metal films sputtered from a full target in argon. On the contrary, for the gas feed to discharge, aD of the oxide films, sputtered from target with four holes of diameter 2 mm, is very low, 40 times smaller compared to aD of metal films sputtered from a full target in argon. The magnetron discharge with an extremely low deposition rate is very suitable for cleaning and activation of surfaces prior to the film deposition.