SUSTAINED SELF SPUTTERING OF DIFFERENT MATERIALS USING DC MAGNETRON

The increase of the target power density causes not only the deposition rate increase, but also gives the possibility of introducing a new way of magnetron sputtering. With high sputtering rates, the secondary ions of sputtered metal begin to play an important role. In the extreme case, the discharge can be sustained with secondary ions only in a so-called 'pure' self-sputtering. When this phenomenon occurs the magnetron sputtering process can go on at the final pressure of the vacuum set, (i.e. 4 x 10(-4) Pa). If means that during self-sputtering (SSS) sustained on metal ions the contamination by inert gas particles has been eliminated. The author has proposed an observation of the relation between the minimum values of the target current, (target current density, target power density) and the working gas (argon) pressure, at which the discharge still exists, as an 'instrument' of the SSS effect. The paper presents a relation I-Tmin (i(Tmin); P-Tmin) versus P-wmin, which was measured during Cu, Ag, Ti, Ni, Ta, Al and stainless steel sputtering. The current-voltage characteristics have been measured. The 'pure' SSS effect has been observed during Cu, Ta, Ag and stainless steel sputtering. For other materials, the target current increase caused a decrease of the sputtering process pressure. Planar magnetrons of very high efficiency were used. Targets of 50, 100 and 200 mm in diameter were sputtered at power densities up to 300 W/cm(2).