Ionization enhancement in ionized magnetron sputter deposition

To enhance the ionization level of ionized magnetron sputter deposition, the modulation of sputtering power was examined by using optical emission spectroscopy (OES) and probe analysis of the pulsed plasma as in situ diagnostics when Ag is sputtered in Ar. Probe analysis of internal inductively coupled plasma (ICP) was performed over a range of Ar pressures and rf powers, and harmonic analysis was done using fast Fourier transformation. Medium frequency (55 kHz) sputtering power was pulsed with various on/off duties to recover the 4 or 13.56 MHz excited ICP's electron temperature which is quenched by heavily sputtered metals of low ionization threshold. The volumetric ion fractions of Ag and Ar, estimated by OES, showed distinct increase at 100/100 ms of on-off duty, which resulted in a change in preferred orientation of deposited Ag films from (111) to (200) by 3.6 times in the ratio of integrated diffraction intensities. Moreover, the measured substrate current did not decrease linearly by the expected rate on the basis of on-off duties. (C) 2000 American Vacuum Society. [S0734-2101(00)01301-4].