Substrate effect on the optical properties and thickness of diamond-like carbon films deposited by the RF PACVD method

The paper presents analyses of the optical properties and thickness of diamond-like carbon (DLC) films deposited on oxidized silicon wafers and silicon wafers with various resistivity and different crystallographic orientations. The influence of the parameters of the radio frequency plasma-assisted chemical vapor deposition (RF PACVD) process, notably the duration of the deposition process and the negative self-bias voltage of RF-powered electrode, on the optical properties and thickness of the DLC film were investigated. These properties were determined by spectroscopic ellipsometry. To the best of our knowledge, this is the first comparative analysis of these properties for various silicon and oxidized silicon substrates. Our results show that the substrate has a significant influence on both the optical properties and the thickness of the DLC film. The differences observed are highly dependent on the discussed process parameters.

Research Highlights►Substrate has a significant influence on both the optical properties and the thickness of the DLC film. ►Films deposited on silicon substrate of lower resistivity are thicker than those deposited on higher-resistivity substrates. ►The increase in thickness correlates well with an increase in the refractive index.