Magnetron Configuration to Enhance Deposition Rate in High Power Impulse Magnetron Sputtering

摘要

High power impulse magnetron sputtering (HIPIMS) discharges are known to produce ahighlyionizedmetal deposition flux with ionization degree of up to 70%. It has been shown that the geometry of magnetic fields near the substrate can strongly influence the spatial distribution of film thickness. This research shows that the magnetic field strength at the cathode can influence the deposition rate without affecting uniformity. The magnetron's magnetic field was changed in a way that the shape of magnetic field near the substrates remained constant while the volume of the magnetic trapping tunnel near the target and the maximum tangential component Bt reduced.rnBy decreasing Bt from 50 mT to 17 mT, the specific deposition rate of Cr increased from 270 to 360 nmh~(-1)kW~(-1). Since the peak and average discharge power were maintained constant, the total peak plasma density remained constant at 9×10~(11)cm~(-3) as measured by Langmuir probes. The metal ion-to-gas ion ratio was high at 1.7 as measured with energy-resolved mass spectrometry. The ratio and density of double charged metal ions were maintained high for magnetic fields down to Bt = 25 mT and were associated with a dense film microstructure and high deposition rate. As the field reduced to very low values of Bt = 17 mT, the metal ion-to-gas ion ratio dropped to 0.8 and the film microstructure developed well defined columns.rnThe changes in deposition rate, metal ion content, and coating structure are related to the volume of the confining magnetic field.