| Magnetron sputtering has been widely applied in the coating of complex-shaped workpieces. For complex-shaped workpieces, it means that the angles between workpiece surfaces and sputtering target are different, which results in an inclination angle deposition. During the inclination angle deposition, a self-shadowing effect occurs, which leads to obvious differences at each surface on workpiece, such as film thickness, structure and properties. The failure is easy to occur where the performance is bad in service, eventually reducing service life of films.Hence, in order to increase the film uniformities of complex-shaped workpieces (including stress, structure, hardness and corrosion resistance et. al.), the control of deposition processes is very important in eliminating the self-shadowing effect, such as working pressure and substrate bias voltage, which affects the mean free path of sputtered particles and the ion energy, respectively. The trajectory and incident angle of particles arriving to substrate will be changed. In view of these problems above, film residual stress is measured by wafer curvature method, which is studied and supplemented in this paper. And after that, TiN films are prepared on Si and stainless steel substrates with inclination angles by direct current magnetron sputtering (DCMS) and high power pulsed magnetron sputtering (HPPMS), respectively. The influences of substrate bias voltage and working pressure on film structure and mechanical properties are studied. To modulate TiN film stress, the zigzag-like structure of vertical and inclined columnar crystal multilayers is prepared by alternately shifting the sputtering angle, and the effects of the inclined layer thickness on film stress, hardness and wear-resisting property are studied. At last, in order to improve the uniformities, the pulse widths during TiN film deposition for HPPMS are raised to increase metal ionization degree, and the film structure, properties and the uniformities of TiN films deposited on substrates with different inclination angles are further investigated. The main research results are as follows.(1) In wafer curvature method, the effects of the fixation on Si (100) wafer and wafer size on film stress were studied. The results showed that the fixed end restrained the deformation of Si wafer under film stress, which led to an obvious difference in the stress values measured at different positions along the width and length directions. The measured stress values were more consistent at different positions along the length direction when the length/width ratios of wafer were equal to or larger than 3:1. So, the length/width ratios of wafer should be greater than or equal to 3:1 and the profile should be measured along the length direction in wafer curvature method.(2) TiN films were deposited on Si substrates with inclination angles by DCMS. The influence rules of substrate bias voltage and working pressure on the film structure and properties were studied in this paper. The results showed that the self-shadowing effect would occur when Si surface is tilted away the target normal. This led to the columnar crystal of TiN films growing along the direction tilted away the substrate normal and a porous film structure. The increased bias voltage improved the density and hardness of films deposited on substrates with inclination angle. But the self-shadowing effect still existed in films and was not fundamentally eliminated. And also the increase of working pressure was powerless in eliminating the effect because of more porous structure.(3) In order to modulate TiN film stress, the zigzag-like film structure of vertical and inclined columnar crystal multilayers was prepared on Si and stainless steel substrates by alternately shifting the sputtering angle, and the effects of the inclined layer thickness on film stress, hardness and wear-resisting property were studied. The results showed that the zigzag-like structure was effective to modulate the residual stress of TiN multilayer films, and the hardness and wear-resisting property of TiN multilayer films could be increased by the control of the inclined layer thickness.(4) The influences of substrate bias voltage and working pressure on the self-shadowing effect, film structure and properties were studied during the Ti and TiN films deposition by HPPMS. The results showed that the collisions between sputtered particles and gas molecules increased by increasing working pressure, which made the columnar crystal of the Ti films deposited on Si substrate growing along the substrate normal while the film density and hardness significantly decreased. This showed that high pressure just mitigated the self-shadowing effect. The increased bias voltage made that the metal ions deflected under strong electric field and migrated easily under high energy. This led to the columnar crystal of TiN films deposited on Si substrate growing along the substrate normal and the film structure denser. At last, the self-shadowing effect was eliminated fundamentally. And the ions bombardment was enhanced by the increase of bias voltage, the film stress exhibited more compressive.(5) In order to improve the uniformities of films deposited on complex-shaped workpieces, the pulse widths during TiN film deposition by HPPMS were increased to enhance the metal ionization degree, and the structure, properties and the uniformities of TiN films deposited on Si and stainless steel substrates with different inclination angles were further investigated. The results showed that the longer pulse was helpful to increase the metal ionization degree at same duty cycle. More sputtered ions could arrive at the surfaces tilted away target under strong electric field, which densified the films deposited on these surfaces. At last, the uniformities including structure, hardness and corrosion resistance of TiN films deposited on different surfaces were improved. |
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