Sputtering Coating When high-energy particles bombard the solid surface, the particles on the solid surface can gain energy and escape the surface to be deposited on the substrate. Sputtering phenomenon began to be used in coating technology in 1870, and gradually used in industrial production after 1930 due to the increase in deposition rate. The commonly used two-pole sputtering equipment is shown in Figure 3 [Schematic diagram of two vacuum coating pole sputtering]. Usually the material to be deposited is made into a plate-a target, which is fixed on the cathode. The substrate is placed on the anode facing the target surface, a few centimeters away from the target. After the system is pumped to a high vacuum, it is filled with 10~1 Pa gas (usually argon), and a voltage of several thousand volts is applied between the cathode and the anode, and a glow discharge is generated between the two electrodes. The positive ions generated by the discharge fly to the cathode under the action of an electric field and collide with the atoms on the target surface. The target atoms that escape from the target surface due to the collision are called sputtering atoms, and their energy is in the range of 1 to tens of electron volts. The sputtered atoms are deposited on the surface of the substrate to form a film. Unlike evaporation coating, sputter coating is not limited by the melting point of the film material, and can sputter refractory substances such as W, Ta, C, Mo, WC, TiC, etc. The sputtering compound film can be sputtered by the reactive sputtering method, that is, the reactive gas (O, N, HS, CH, etc.) is
added to the Ar gas, and the reactive gas and its ions react with the target atom or the sputtered atom to form a compound (such as oxide, nitrogen) Compounds, etc.) and deposited on the substrate. A high-frequency sputtering method can be used to deposit the insulating film. The substrate is mounted on the grounded electrode, and the insulating target is mounted on the opposite electrode. One end of the high-frequency power supply is grounded, and one end is connected to an electrode equipped with an insulating target through a matching network and a DC blocking capacitor. After switching on the high-frequency power supply, the high-frequency voltage continuously changes its polarity. The electrons and positive ions in the plasma hit the insulating target during the positive half cycle and the negative half cycle of the voltage, respectively. Since the electron mobility is higher than that of the positive ions, the surface of the insulating target is negatively charged. When the dynamic equilibrium is reached, the target is at a negative bias potential, so that the positive ions sputtering on the target continues. The use of magnetron sputtering can increase the deposition rate by nearly an order of magnitude compared with non-magnetron sputtering.
Post time: Jul-31-2021