Gas phase diagnostics on high power pulsed magnetron sputtering using double-pulse target-voltage*

 A diamond-like carbon (DLC) is an amorphous carbon containing both sp² bond and sp³ bond structures. Ion flux to substrate and ion energy around 100 eV is essential to increase the sp³ bond in the DLC film. An increase in the ion flux is expected by using high power pulsed magnetron sputtering (HPPMS) with double-pulse target-voltage. In this study, the energy distribution of Ar⁺ and C⁺ was measured by energy-resolved mass spectrometry. The relationship between behavior of ion and film quality of DLC film was investigated.

 

 The HPPMS power supply was connected to the carbon target. The condition of first pulse was the frequency of 400 Hz, the pulse width of 25 μs and the peak power density of 1.5kW/cm². The applied voltage of second pulse was -600 V and the pulse width was 10 μs. The time interval between first and second pulses was varied from 20 μs to 50 μs. The pressure was 0.5 Pa and the gas flow rate of Ar was 5 sccm. The distance between the target and the orifice was 80 mm.

 

 The fluxes of Ar⁺ or C⁺ at time interval of 20 μs were 1.8 and 1.3 times higher than those of the single pulse, respectively. In addition, the fluxes of Ar⁺ or C⁺ decreased with increasing the time interval between the first and second pulses.