[18p-C309-1~13] 8.2 Plasma deposition of thin film, plasma etching and surface treatment

[18p-C309-8] Negative plasma potential in Mg-CF₄ direct current reactive sputtering discharge

〇Eiji Kusano¹ (1.Kanazawa Inst.Technol.)

Keywords:Reactive sputtering, Negative ions, Electronegative plasma

Plasma potential in Mg-CF₄ direct current reactive sputtering discharge has been evaluated by probe measurements as a function of CF₄ concentration in Ar-CF₄ discharge gas. With increasing CF₄ concentration, the plasma potential shifted to negative and reached approximately – 50 V for 100%-CF₄ discharge at a discharge pressure of 1.2 Pa. Simultaneously, under this condition, the floating potential reached -80 V. In the second derivative of the probe current-voltage curves, the shoulder peaks corresponding to the current by energetic negative ions have been investigate. It is further observed that the shoulder peak intensity in the second derivative curves well correlates to the plasma potential shift. It is concluded that the negative shift of plasma potential in Mg-CF₄ direct current reactive discharge results from the negative ion formation.