Chamberless plasma deposition of glass coatings on plastic

Abstract

A chamberless, remote plasma deposition process has been used to coat silicon and plastic substrates with glass at ambient conditions. The films were deposited by introducing an organosilane precursor into the afterglow of an atmospheric plasma fed with helium and 2 vol% oxygen. The precursors examined were hexamethyldisilazane, hexamethyldisiloxane, tetramethyldisiloxane, tetramethylcyclotetrasiloxane and tetraethoxysilane. With hexamethyldisilazane, glass films were deposited at rates of up to 0.25 µm min−1 and contained as little as 13.0 mol% hydroxyl groups. These films exhibited low porosity and superior hardness and abrasion resistance. With tetramethyldisiloxane, glass films were deposited at rates up to 0.91 µm min−1. However, these coatings contained significant amounts of carbon and hydroxyl impurities (∼20 mol% OH), yielding a higher density of voids and poor abrasion resistance. In summary, the properties of glass films produced by remote atmospheric plasma deposition strongly depend on the organosilane precursor selected.