Low residual stress in hydrogenated amorphous silicon-carbon films deposited by low-temperature PECVD

Abstract

Low residual stress in hydrogenated amorphous silicon-carbon (a-SixC1-x:H) films prepared by plasma-enhanced chemical vapor deposition (PECVD) at temperature range of 100–200 °C was obtained. Profilometry, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) measurements were carried out to characterize the films. The residual stress of each deposited film was calculated using profilometry measurements and the Stoney equation. The results showed that the residual stress decreases as the power density is reduced, or the temperature or the silane/methane ratio are increased. There is a deposition pressure at around 750 mTorr at which low residual stress is promoted. The residual stress showed a correlation with the carbon incorporation in the form of C–Hn molecules. The residual stress depends on the deposition regime: assisted either by silane radicals (also known as “silane starving plasma” (SSP)) or by both silane and methane radicals. Considering that the carbon incorporation under SSP regime is more controlled, there is a higher probability of having low residual stress in this regime. In agreement with the characterization, the most favorable PECVD parameters were selected to obtain a-SixC1-x:H films with low residual stress (below 100 MPa) within the temperature range (100–200 °C). These results are useful in areas such as flexible electronic devices, implantable devices, microfluidic systems, and microelectromechanical systems, among others, in which the materials and the parameters of fabrication are degraded or modified by temperature above 200 °C. Keywords: Plasma-enhanced chemical vapor deposition, Hydrogenated amorphous silicon-carbon film, Residual stress, Fourier-transform infrared spectroscopy, Atomic force microscopy