Characteristics of triode magnetron sputtering: the morphology of deposited titanium films

Abstract

This paper presents a modification to conventional diode magnetron sputtering systems that results in higher ionisation rates with a consequent possibility of maintaining the discharge at lower pressures. The introduction of a grounded or positively biased grid in front of the target increases the target current substantially compared with the diode configuration. In addition, the discharge can be maintained at a lower target voltage, thus increasing the range of deposition rate. With a low-pressure discharge maintained during film deposition, the mean free path of the sputtered atoms increases. As a consequence, they reach the substrate with a high energy and, thus, a high-density film is obtained. Therefore, by using the triode magnetron configuration and setting the substrate temperature to 100 °C, it is possible to deposit a titanium film having a similar morphology to one deposited in the diode system at 400 °C. Finally, the electrode placed in front of the cathode probably produces a more homogeneous spatial distribution of electron density, resulting in a significantly higher discharge stability in the triode configuration.