Characterization of Residual Stress in a-SiC:H Deposited by RF-PECVD for Manufacturing of Membranes for Cell Culture

Abstract

Hydrogenated amorphous silicon carbide (a-SiC:H) was deposited by radiofrequency-plasma enhanced chemical vapor deposition (RF-PECVD) on monocrystalline silicon substrates with different process parameters in order to analyze the residual stress, and the roughness and uniformity of the films, which are the most important characteristics in the production of membranes for cell culture. The residual stress was calculated using Stoney's equation by measuring the thicknesses of the substrate and the deposited film, in addition to the radius of curvature of the substrate with and without deposited material. From the results it was observed that as power increases from 15 to 30 W, the residual stress increases from -180 to -400 MPa. Even at low power, the residual stress is high. However, an annealing process at 450 °C in N₂ atmosphere significantly reduces the residual stress to 7 MPa. It was found that the film uniformity increases when the pressure rises in the process chamber from 450 to 900 mTorr. Finally, the RMS roughness (0.7 to 5.1 nm) can be controlled by the power and pressure, allowing us to obtain a material with excellent morphological characteristics for the adherence and growth of specific cells.