AVS 46th International Symposium
    Vacuum Metallurgy Division Wednesday Sessions
       Session VM-WeM

Paper VM-WeM8
Plasma Treatment of Polycarbonate for Improved Adhesion

Wednesday, October 27, 1999, 10:40 am, Room 620

Session: Advanced Surface Treatments and Coatings
Presenter: A. Hofrichter, CNRS Ecole Polytechnique, France
Authors: A. Hofrichter, CNRS Ecole Polytechnique, France
P. Bulkin, CNRS Ecole Polytechnique, France
B. Drévillon, CNRS Ecole Polytechnique, France
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The deposition of silicon alloys for protective and optical coatings on polymers is of increasing interest. The understanding of the plasma polymer interaction is of prime importance here. In this work we report a study of the influence of various plasma-treatments on polycarbonate (PC) in order to clarify the adhesion mechanisms of plasma deposited silica films. Treatments and depositions were carried out in a low pressure (1 mTorr range) integrated distributed 2.45 GHz microwave electron cyclotron resonance reactor, which allows the deposition of dense stoechiometric silica at room temperature. The plasma-polymer interaction is studied by in-situ spectroscopic ellipsometry from near UV to infrared and ex situ Raman spectroscopy and atomic force microscopy. The influence of process parameters, such as power and gas composition is studied. To get better insight into the plasma modification mechanisms thin polymer layers, spincoated onto various substrates were used. This allows a precise determination of the absorption properties and the thickness evolution of the plasma modified surface layer by UV-visible ellipsometry. The absorption in the PC layer was found to increase in the UV and is attributed to the different reaction products of photo-Fries rearrangements. Particular attention was taken to evaluate the contribution of the VUV photons. The chain scission and crosslinking of pure and commercial grade polycarbonate is studied by gel permeation chromatography and correlated to the ellipsometric results. Finally we discuss the influence of the treatement on the silica adhesion, evaluated by microscratch test measurements.