TIN FILMS GROWN BY REACTIVE MAGNETRON SPUTTERING WITH ENHANCED IONIZATION AT LOW DISCHARGE PRESSURES

TiN films were produced by reactive magnetron sputtering at a discharge pressure of 0.09 Pa on substrates placed 200 mm away from the magnetron target, using a sputtering system with enhanced ionization by means of multipolar magnetic confinement. The effects on film properties are reported for two ranges of values: an external substrate bias U(s) of from -35 to -150 V, and a floating potential U(fl) of from -24 to -45 V. All films show a dense microstructure, a smooth surface and shiny golden color. The microhardness HV is between 2000 and 2600 kg mm-1, a high critical load of up to L(c) = 58 N in scratch tests and the coefficient of friction against a cemented carbide counter ball is between 0.12 and 0.22. The color co-ordinates L*, A* and B* depend on the bias voltage. The brightness L* reaches 78 CIELAB units. The properties of films prepared at U(s) between -60 and -150 V compare well to those of ion-plated films. The films prepared at [U(s)/< 60 V, or at any of the values for U(fl), exhibit comparatively low compressive microstresses down to 2.2 GPa and low microstrain down to 3.5 x 10(-3). These films show single (111), (200) or (220) textures, or a mixed (200) + (111) texture, depending on the U value at which they were prepared.