Deposition of nitrogen-containing diamond-like carbon films on acrylic substrates by an ion beam process

The insufficient adhesion of diamond-like carbon (DLC) film deposited on acrylic substrate was enhanced using ion beam treatment with nitrogen as a working gas before and during the deposition. The stress-related, structural and optical characteristics of the nitrogen-containing DLC films (N-DLC) were systematically studied as functions of nitrogen flow. The stress in the film decreased as the nitrogen flow increased. The nitrogen content was uniform throughout the films, which were more graphitic at higher nitrogen flow. The N-DLC films had higher extinction coefficients than those of DLC films, implying that the incorporation of nitrogen reduced the transparency of the films. The adhesion tests revealed that N-DLC films were firmly deposited onto the acrylic substrates. Nitrogen incorporation reduced the internal stress and N-2 ion pretreatment activated the acrylic surfaces, both enhancing the film's adhesive strength to the acrylic substrate. (C) 2004 Elsevier Ltd. All rights reserved.