Characterization of Residual Stress in a-SiC:H Deposited by RF-PECVD for Manufacturing of Membranes for Cell Culture
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Characterization of Residual Stress in a-SiC:H Deposited by RF-PECVD for Manufacturing of Membranes for Cell Culture O. Gelvez- Lizarazo and C. Reyes-Betanzo Electronics Department, National Institute for Astrophysics, Optics and Electronics, P.O. Box 72840, Puebla, Mexico. ABSTRACT Hydrogenated amorphous silicon carbide (a-SiC:H) was deposited by radiofrequencyplasma 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. INTRODUCTION Nowadays, technology has advanced in the development of biosensors and biomedical systems, whose manufacturing and performance are dependent on new materials developed in the laboratory, seeking for biocompatibility and multifunctionality. It is of significant importance to research and develop new materials that will contribute to the technological growth in the health sector. Due to the complexity of the production of biosensors, the materials must be processed using manufacturing lines for microelectronics; a-SiC:H integrates silicon, which is the base of the microelectronics industry, and carbon, a fundamental element in the organic chains present in living organisms. In this work, we discuss the effect of the processing parameters on the deposition of amorphous silicon carbide with specific characteristics for the manufacture of membranes for attachment and / or cell culturing, which could be used in biosensors or tissue generation for regenerative medicine [1, 2]. EXPERIMENTAL DETAILS Initially, a cleaning process was performed on crystalline silicon substrates (n-type, 0.5-3.7 Ω cm) with (100) orientation and thickness of 300 μm, by using a solution of hydrofluoric acid (HF) and deionized water in a 1:7 concentration to remove the native oxide. This was followed by degreasing with trichlorethylene (TCE) and acetone in an ultrasonic bath for 10 minutes for each one of these solvents. Subsequently, films of a-SiC: H were deposited by RF-PECVD
(13.56 MHz) using silane (SiH4 diluted in H2 at 10%) and methane (CH4) as p
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