Study of the cathode potential in a sputtering discharge by pulsing the reactive gas: case of a W target in an Ar-O2 atmosphere

Parreira, Nuno M.G., Polcar, Tomáš and Cavaleiro, Albano (2007) Study of the cathode potential in a sputtering discharge by pulsing the reactive gas: case of a W target in an Ar-O2 atmosphere. Plasma Processes and Polymers, 4 (1), 62-68. (doi:10.1002/ppap.200600050).

Abstract

The process we used was d.c. magnetron sputtering, and we studied both the conventional process, using a constant flow of oxygen, and the process in which we pulsed the reactive gas. Square regulation signal with different pulsing periods (T) and oxygen injection time (ton) was used in the reactive gas pulsing (RGP), while the partial argon pressure was kept constant for all depositions. The oxygen flow rate during the injection time was sufficient to switch the process to compound sputtering mode, while the oxygen flow was stopped in the rest of period to allow cleaning of target. Sputtering experiments have shown that the instability phenomena, typical of the reactive sputtering process and known as the “hysteresis effect”, are relatively weak due to the small reactivity of tungsten. The influence of the pulsing period and of the oxygen injection time on the deposition parameters is discussed in relation to the poisoning effect. It has been shown that d.c. magnetron sputtering with the oxygen pulsing is a suitable method to prepare tungsten oxide films. This process is very stable, leads to multilayered W-O coatings, and the deposition rates are slightly lower than those of obtained during the conventional process.

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Contributors

Author: Tomáš Polcar

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