AVS 53rd International Symposium
    Advanced Surface Engineering Wednesday Sessions
       Session SE2-WeA

Paper SE2-WeA8
Pulsed RF PECVD of a-SiN@sub x@:H Alloys: Film Properties, Growth Mechanism and Applications

Wednesday, November 15, 2006, 4:20 pm, Room 2007a

Session: Pulsed Plasmas in Surface Engineering
Presenter: R. Vernhes, Ecole Polytechnique of Montreal, Canada
Authors: R. Vernhes, Ecole Polytechnique of Montreal, Canada
O. Zabeida, Ecole Polytechnique of Montreal, Canada
J.E. Klemberg-Sapieha, Ecole Polytechnique of Montreal, Canada
L. Martinu, Ecole Polytechnique of Montreal, Canada
Correspondent: Click to Email
In PECVD of thin films, control of plasma chemistry and plasma-surface interaction during the growth are critical for the tailoring of film composition and microstructure. In this context, pulsing the plasma provides additionnal parameters (frequency, duty cycle) to control the deposition process, while decreasing the thermal load on the substrate. In this work, we present the pulsed PECVD of a-SiN@sub x@:H alloys, the films' properties being varied simply by adjusting the duty cycle of the RF power, while keeping the N@sub 2@/SiH@sub 4@ gas mixture constant. Spectroscopic ellipsometry analysis in the UV-VIS-NIR and FIR ranges, atomic force microscopy, and elastic recoil detection reveal strong variations of optical properties (1.88 @<=@ n @<=@ 2.75, 10@super -4@ @<=@ k @<=@ 5x10@super -2@ at 550 nm), microstructural characteristics (1.3 nm @<=@ surface roughness @<=@ 8.3 nm), and chemical composition (0.3 @<=@ x @<=@ 1.3) of the coatings as a function of duty cycle. This behavior is interpreted in terms of radical concentration changes in the gas phase and variations of the average ion bombardment energy at the film surface, leading to modifications of the growth mechanism. Using this process, we fabricated two types of a-SiN@sub x@:H-based thin film devices, namely (i) a high-quality Fabry-Perot optical filter deposited on plastic substrate without monitoring, and (ii) a superlattice structure displaying a photoluminescence signal four times higher than the reference single layer. These two examples of applications point out the main advantages of this pulsed RF PECVD process, in particular low deposition temperature, reproducibility, versatility and ease of use.