Atmospheric plasma deposition of abrasion resistant coatings on plastic

Abstract

Summary form only given. The plasma-enhanced chemical vapor deposition (PECVD) of silicon dioxide films has been examined in a low temperature, atmospheric pressure discharge. A mixture of 2.0 vol% oxygen in helium was utilized in a capacitive discharge operating at 100 W RF power and a neutral gas temperature of /spl sim/100/spl deg/C. Several silicon precursors were studied, including tetramethyldisiloxane (TMDSO), tetramethylcy-clotetrasiloxane (TMCTS), tetraethoxysilane (TEOS), and hexa-methyldisilazane (HMDSN). After growth, the thickness, refractive index and composition of the silicon dioxide films were determined by ellipsometry, Fourier-transform infrared spectroscopy and Rutherford backscattering. Abrasion tests were performed on films deposited on plastic substrates. Glass films could be deposited at rates up to 1.0 micron/minute using TMDSO. However, these films contained 5.0 to 10.0 atom% carbon and hydrogen, and abraided easily during scratch tests. Feeding HMDSN to the oxygen plasma resulted in the deposition of silicon dioxide films that were free of nitrogen and carbon (<0.5 atom%), contained /spl sim/2.0 atom% hydrogen, and displayed excellent scratch resistance. The maximum deposition rate obtained using HMDSN was 0.3 microns/minute. It was found that the deposition rate increased with RF power, oxygen partial pressure up to 10 Torr, and decreasing distance between the plasma source and substrate (2.0 to 10.0 mm). At the meeting, we will discuss the relationship between the plasma chemistry and the properties of the silicon dioxide coatings.