a) Sputtering is a very important physical process in plasma engineering of thin films and coatings. In one or two paragraphs describe what sputtering is. Illustrate your answer with diagrams and mention concepts such as lattice atom rearrangement, energy transfer on bombardment, surface binding energy, the effect of different masses, sputter yield. b) Fig. Q2 shows a plot of the sputter yield versus bombarding energy for the sputtering of a number of different materials (zinc, copper, aluminium, silicon and titanium) by argon ions. Sputter yield 10 0.1 0.01 10 100 lon enerav (eV) Zn Fig. Q2. Cu Al Si 1000 10,000 100,000 Ti i) ii) iii) iv) Define the term sputter yield in terms of particle fluxes Why do the sputter yields start to decrease at very high ion energy? At 1000 eV bombarding energy why is the sputter yield of zinc much higher than that of titanium? What is the sputter yield of titanium when the bombarding argon ion velocity is 6.95 x 104 ms ? c) Sketch the design for a planar circular magnetron sputtering source inside a vacuum vessel, operated by a DC power supply, used to deposition thin films and coatings. Label your design carefully showing all the important features including: The magnets and magnetic field line; The position and shape of the target; The substrate; The vacuum vessel walls; The gas inlet; The power supply system; The magnetic trap region in the plasma; The typical trajectories of the ions and electrons and sputtered particles in the plasma; Regions of dense plasma in the system. d) What is the gyro-frequency of an electron trapped on a magnetic field line if the magnetic field strength is B = 0.01 T?