The ion current density and spectroscopic study in a straight magnetic filtering arc deposition system

Abstract

The changes of plasma states during cathodic arc discharges of Ti and TiAl under various magnetic fields of straight magnetic solenoid were analyzed by Langmuir probe method and optical emission spectroscopy (OES). The ion emission intensity of Ti II for Ti arc discharge was enhanced by a factor of 2. with increasing magnetic field up to 150 Gauss compared to that under no magnetic fields. For discharging TiAl with ambient N 2 under 150 Gauss, however, the emission of Al exhibited dominant neutral emission of Al I only with slight increase of ionized Al II emission while Ti II emissions were increased at a similar ratio as measured in Ti discharge. The enhancement of electron density induced by a straight solenoid magnetic field promoted the effective ionization of metal vapors, therefore producing a high fraction of ionized vapor flux including macroparticles, which contributed to the increase of deposition rate and sputtering of macroparticles seated on the film surface by energetic metal ion flux. The changes of surface morphology and film formation behaviors of TiN and (TiAl)N arc was evaluated with a variation of external magnetic field in conjunction with plasma conditions obtained from Langmuir probe, OES and XRD analyses. The corresponding hardness and friction coefficient variations are also illustrated.