High-rate deposition of copper thin films using newly designed high-power magnetron sputtering source

Abstract

We have deposited copper (Cu) thin films on Si(100) and glass substrates in the growth temperature range between 573 and 753 K using a pulsed DC magnetron sputtering method. Based on the magnetic field simulation, we have designed and constructed a high-power (120×10 −4 W/m 2) unbalanced magnetron sputtering (UBM) source for high-rate deposition. The maximum deposition rate of the newly developed sputtering source under a target power density of 115×10 −4 W/m 2 we have obtained is 2.8 μm/min. This is five times higher than that using the conventional sputtering method, and the sputtering yield also reached 70% due to low voltage and high-current Cu-accelerated ions. We have also adapted an ion extraction grid between the Cu target and substrate. Although the growth rate was decreased to 2 μm/min, XRD and XPS showed that highly oriented polycrystalline Cu(111) thin films without carbon and oxygen impurities were obtained with lowest electrical resistivity of 2.0×10 −2 μΩm at a target power density of 96.7×10 −4 W/m 2, substrate temperature of 723 K, and working pressure of 1.3×10 −1 Pa. During film deposition, moreover, plasma diagnostics was also carried out in situ by optical emission spectroscopy analysis.