Description of a hybrid PECVD-PVD process: Application to Zn–Si–O and Ti–Si–O composites thin films

A radio frequency hybrid process where sputtering and plasma enhanced chemical vapour deposition (PECVD) occur simultaneously is studied to describe the specificity it gains when the two techniques are merged. A model is developed to describe how the deposition rate evolves when the flow rate of the PECVD precursor increases. First, it is shown that it is constant below a critical value of the precursor flow rate because of the wind effect due to sputtering that strongly limits the transport of the precursor. Then it increases almost linearly with the precursor flow rate when PECVD and sputtering simultaneously occur. Finally, above a certain threshold in the precursor flow rate, the surface of the target is poisoned by the precursor and composite thin films can no longer grow. The previous model is deduced from results obtained in deposition of Zn–Si–O and Ti– Si–O thin films. These composites are synthesised respectively by sputtering of zinc and titanium targets in a vapour of oxygen and hexamethyldisiloxane (HMDSO–Si2C6H18O). Limitations of the model used are also discussed.