Development and optimisation of a SiO2 PVD technique based on the thermal decomposition of PDMS

Abstract

This work reports the development of a novel and facile physical vapour deposition (PVD) system for SiO₂ deposition with a wide and controllable range of final film thicknesses. An investigation of the steady-state deposition temperature, heating rate, and PDMS source mass dependence of the deposited SiO₂ layer thickness was performed using a variety of experimental techniques. SiO₂ layers were characterised by scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), grazing incidence attenuating total reflection Fourier transform infrared spectroscopy (GATR-FTIR), contact profilometry (CP), and white light profilometry (WLP). It was found that the thickness of the SiO₂ layer was linearly proportional to the PDMS source mass for large source masses with a nonlinear (parabolic) relationship for smaller source masses, but a non-monotonic relationship was observed between thickness and source material heating rate. The steady-state deposition temperature above the decomposition threshold did not directly affect layer thickness within the range investigated but, the lower the temperature, the greater the film uniformity.