Role of the Plasma Activation Degree on Densification of Organosilicon Films

Abstract

The possibility of controlling the density of organosilicon films was investigated by tuning the plasma activation degree without providing extra energy to the structure, as usually reported in the literature. For this purpose, thin films were deposited in plasmas fed with hexamethyldisiloxane/Ar mixtures at a total pressure of 9.5 Pa. The power of the radiofrequency excitation signal, P, ranged from 50 to 300 W to alter the average energy of the plasma species while the electrical configuration was chosen to avoid direct ion bombardment of the growing films. In this way, it was possible to evaluate the effect of P on the film properties. Thickness and deposition rate were derived from profilometry data. X-ray energy dispersive and infrared spectroscopies were, respectively, applied to analyze the chemical composition and molecular structure of the layers. Surface topography and roughness were determined by atomic force microscopy while nanoindentation was used to evaluate the mechanical properties of the films. From electrochemical impedance spectroscopy the total resistance to the flow of electrolyte species was derived. The main alteration observed in the structure with changing P is related to the proportion of the methyl functional which remains connected to the Si backbone. Chain crosslinking and film density are affected by this structural modification induced by homogeneous and heterogeneous plasma reactions. The density increase resulted in a film with hardness comparable to that of the silica and more resistant to the permeation of oxidative species, but preserving the organosilicon nature of the structure.

Effect of Plasma Oxidation Treatment on Production of a SiOx/SiOxCyHz Bilayer to Protect Carbon Steel Against Corrosion

“…Finally, when P is elevated beyond 50 W, a further drop is observed in R T indicating the deterioration of the barrier properties both by the drop of the layer thickness and by the formation of a completely oxidized, but porous layer. It is noteworthy that the results obtained for carbon steel, organosilicone film, and silicon oxide type (200 and 300 W) are similar to those found in other studies 4,29,41 , ensuring the reliability of the analyses, although they were performed once for each condition. With these results, it can be inferred that the degree of crosslinking of the structure, together with the layer thickness, are the most relevant factors to inhibit the flow of species further than its stoichiometry.…”

“…In another work, Rangel et al 41 deposited thin films using mixtures of HMDSO and Ar for establishment of the plasmas. The excitation power was varied from 50 to 300 W to change the average energy of the plasma species while the electronic configuration was selected to avoid direct ion bombardment of the films during deposition.…”

Synthesis of multifunctional chlorhexidine-doped thin films for titanium-based implant materials

“…The low energy ion bombardment thus induced can eject CHX fragments incorporated in the film deposition process. This mechanism, proposed by Yasuda [33], and schematized by Rangel et al [34], would be favored in this research by the increase in the free mean electron path caused by the interruption in the flow of HMDSO. It would also explain the reduction in the Cl ratio of the surface if the sputtering time were increased.…”

Fabrication of SiC-Type Films Using Low-Energy Plasma-Enhanced Chemical Vapor Deposition (PECVD) and Subsequent Pyrolysis

“…To measure this ratio, we carried out EDS measurements in order to determine the atomic composition of the films. EDS has been shown previously to be an effective method for determining the elemental composition of silicon-based polymer films. , Table shows the atomic composition of each film based on the EDS testing.…”