Stress reduction of PACVD amorphous diamond coatings by boron addition

Veit Wagner, E. Dekempeneer, Jan Geurts, L. Van Ijzendoorn, Robert Sporken, Roland Caudano

    Research output: Contribution to journalArticle

    Abstract

    The applications of super hard coatings of diamond-like carbon (DLC) films are often limited by adhesion problems caused by intrinsic stress in the deposited layer due to the PACVD growth process. One approach to reduce the stress are less optimal process parameters. However, they also affect the desired high hardness of the films. Our approach in this study is to add B2H6 to the gas mixture, which shifts the composition towards another very hard compound (B4C). A sequence of amorphous BxC1-x:H films with a thickness of 0.5μm and a boron content between 0 and 50 at.-% were deposited on silicon substrates using a capacitively coupled r.f PACVD reactor. The tribological film properties and the internal stress were determined by depth-sensing indentation and laser reflection measurements. For an addition of x ≥5 at.-% boron the decrease of the internal film stress is found to be clearly larger than the effect on the hardness value. For boron contents x > 18% the internal stress is reduced by a factor of 5 while the reduction of hardness is only a factor of 2.3. For microscopic structure analysis Raman and infrared spectroscopy are applied. They reveal an increasing hydrogenation of the carbon network. Therefore, the softening is attributed to a boron induced modification to a more polymeric-like material.
    Original languageEnglish
    Pages (from-to)183-188
    Number of pages6
    JournalMaterials Research Society Symposium Proceedings
    Volume436
    DOIs
    Publication statusPublished - 1997

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