A Global Model of Chemical Vapor Deposition of Silicon Dioxide by Direct-Current Corona Discharges in Dry Air Containing Octamethylcyclotetrasiloxane Vapor

Abstract

A model of the electron distribution in direct current corona plasmas is combined with a global chemistry model and a two-dimensional transport model to predict the rate of chemical vapor deposition of silicon dioxide on the discharge wire in both positive and negative discharges in dry air containing octamethylcyclotetrasiloxane. The gas-phase chemistry includes reactions to form atomic oxygen (O) and additional global reactions to form gaseous silicon dioxide precursors by the impact reactions of electrons and atomic oxygen with silicone molecules. Surface chemistry is approximated by a single step global reaction from gaseous to solid silicon dioxide. The rate coefficient between atomic oxygen and octamethylcyclotetrasiloxane is estimated from prior experiments to be on the order of 10 −12 cm 3 /molecule-s. The effects of discharge polarity, current, wire radius and air velocity (Peclet number for mass transfer) on the deposition rate are considered. Deposition rates can be minimized by using positive coronas instead of negative coronas for Peclet number less than 18.5. At higher Peclet numbers, the deposition rate is slightly higher in positive corona discharges, but devices used indoors should continue to use the positive corona in order to minimize the production of ozone. The deposition rate in the positive corona is relatively insensitive to air velocity for velocities from 0.044 to 10 m/s −1 . However,it may be minimized by operating the corona with the lowest current that provides adequate performance (e.g., particle charging) and the smallest wire that provides adequate mechanical strength.

Low‐temperature atmospheric pressure plasma conversion of polydimethylsiloxane and polysilazane precursor layers to oxide thin films

“…The addition of a vaporized precursor is a method compatible with many plasma sources. It works with localized plasma jets and torches [ 5‐7 ] as well as with large area corona [ 8 ] or dielectric barrier discharges (DBDs). [ 1,9,10 ] To avoid contact of the plasma with the treated surface, remote plasma reactors are sometimes used.…”

A Hybrid Model to Predict Electron and Ion Distributions in Entire Interelectrode Space of a Negative Corona Discharge

“…In recent years, corona plasmas have been widely used to generate nanomaterials [7]. In addition to useful ions, energetic electrons produced in the corona discharge have led to undesirable ozone production [8]- [11] and deposition of silicon dioxide on the discharge electrode [12], [13]. The authors have previously developed a comprehensive numerical model to predict the distribution and the production rate of ozone in a dc corona discharge along a thin wire in both dry air [14]- [16] and humid air [17].…”

Ion Flow Effects on Negative Direct Current Corona in Air

“…New applications have been continuously emerging, for example gas treatment [4,5], ozone production [6][7][8], surface processing [9], as well as plasma enhanced chemical vapor deposition [10][11][12]. However, the electromagnetic interference and the audible noise caused by corona must be avoided in some occasion, such as high voltage power transmission line [13].…”