Design of functional coatings

Abstract

Based on the principle of macroscopic kinetics, we present the concept of a standard process to compare different rf plasma reactors. Therefore, the mass deposition rate of pure hexamethyldisiloxane (HMDSO) discharges was chosen, since the plasma polymerization of HMDSO is a radical-dominated process and ion-induced effects can be neglected for a wide parameter range. Two experimental series with pure HMDSO discharges were performed within a symmetrical and a strongly asymmetrical rf plasma reactor. The obtained deposition rates were compared to four experimental series taken out of the literature concerning the deposition rates of plasma polymerized HMDSO coatings. While for each reactor design, the "specific energy" W/F was found to describe the deposition rates very well, different apparent activation energies E-a were obtained. To bring the data sets into agreement, a new process constant E-a d(act) is introduced taking the width of the active plasma zone d(act) into account. By this means, functionally gradient SiOC:H films can be designed, e.g., for adhesion, wetting, or barrier improvements. Moreover, processes can be optimized and scaled up. (C) 2005 American Vacuum Society

Activation energy of an asymmetrical, radio frequency discharge with methane

“…Therefore, a similarity parameter Wd act / F, which is equivalent to Ws / A dep p, is identified, as has been demonstrated recently by our group [13,31]. Hence, the differences in E a rely on the longer residence time by flowing through a wider plasma zone, whereby d act is an appropriate parameter.…”

“…Moreover, energetic particle bombardment influences the absolute deposition rate and the film properties [11], but not the apparent activation energy E a , which divides the plasma conditions into a monomer-deficient and an energy-deficient regime [12]. However, to make use of the reaction parameter as a basic parameter as well as for comparison and up-scaling of plasma processes, the true power input and the true flow of gases through the active plasma zone, i.e., the expansion of the plasma, should be known [13]. To avoid questions concerning the expansion of the active plasma zone into the vacuum chamber, a confined geometry of two plane parallel electrodes with a spacing smaller than the plasma length can be used.…”

Diffusionssperrschichten für Polymere - Messtechnische Herausforderung

“…Wird die massenbezogene Abscheiderate in einem Arrhenius-ähnlichen Verfahren aufgetragen (Abb. 3), lässt sich aus der Steigung des linearen Fits, die Aktivierungsenergie ableiten, die für die jeweilige Plasmapolymerisation vonnöten ist [12,16,17]. Es zeigt sich bei der Messung der Sauerstoffpermeation (OX-TRAN 2/20, 23 C, 0 % rel.…”

Stain Repellent Finishing on Fabrics

“…A direct coupling of the RF source (Dressler Cesar 1250) via a matching to the horizontally mounted electrode inside a cylindrical vacuum recipient with a vertical gas flow towards the electrode minimizes power losses and enables a homogeneous treatment of samples lying at the driven electrode of size 10x15 cm 2 . [18] Larger treatments can be performed using a semi-continuous web coater allowing a band width of up to 63 cm, whereby up-scaling can be achieved by regarding the energy flux to the substrate. [19] A mixture of argon with 20 % oxygen at a total flow of 10 sccm was used for a treatment time of one minute, while pressure and power were kept at 20 Pa and 15 W, respectively.…”