Reactive deposition of compounds by a cavity-hollow cathode direct current sputtering system

A new hollow cathode has been designed and applied in a reactive direct current (dc) sputtering system. This hollow cathode with an extra cavity (1.4 cm 3 ) separates the reaction at the substrate from the reaction at the target surface and therefore prevents the target surface (cavity walls) to transit from the metallic sputter mode to the reactive sputter mode. This transition normally happens in reactive dc sputtering systems and it is the cause of a drastic drop in the deposition rate. The physical geometry of this cavity provides larger cathode walls and more efficient use of fast electrons and ions to produce large densities of sputtered and evaporated particles of the target metal. The development of this cavity-hollow cathode was facilitated by comprehensive structural and compositional analysis of some deposited films. By using pure titanium for the target and a mixture of 90% Ar /8% N 2 /2% O 2 for the operating gas, some samples of titanium oxinitride films a few microns thick have been produced. At operating pressure of 0.05 Torr, the measured value for the cathode fall distance inside the cavity is 1.6 mm, showing that the pressure inside the cavity is much higher than the operating pressure in the reactor chamber. The current–voltage characteristics of this system exhibit a switching behavior from a nondischarge mode to a discharge mode with a negative resistance.