Tokyo Metropolitan University, Faculty of Systems Design, Department of Mechanical Systems Engineering
Thin-film process development and its application research using high-density pulsed plasma
We are developing high-performance thin-film processes that leverage the process control flexibility of high-power pulsed sputtering (HiPIMS) technology, which was developed in the early 2000s. By understanding the transient plasma characteristics in pulsed plasma, we can achieve control of ion particles in the plasma, which was previously difficult.
Uniqueness of HiPIMS technology
The flexibility of process control made possible by "pulse" technology
In addition to the high ionization rate achieved by the formation of high-density plasma, a unique feature of HiPIMS technology, unlike conventional technologies, is the addition of a "time axis" to the input parameter set by using "pulses." The ratio and frequency of pulse on/off times, and the non-steady transient response of the plasma characteristics associated with the on/off switching of the pulses, create flexibility in process control.
Peak current density control using HiPIMS pulse conditions
In HiPIMS, the charge stored in a capacitor during the pulse voltage's off-time is applied to the target during the pulse's on-time. If the off-time is kept constant and the pulse width (on-time) is shortened, the same time-averaged input power is released in a shorter time, resulting in a significantly larger peak current value. Besides pulse width, pulse frequency is also a useful method for controlling the peak current value. By keeping the input power constant and increasing the frequency, the number of applied pulses per unit time increases, thus reducing the input power per pulse and lowering the peak current value. Thus, flexible control of peak current density is achieved by adjusting both pulse width and frequency. We have successfully implemented film characteristic control in various hard films.