Adhesion Properties of Metallic and Oxide Thin Films Produced by Several Methods

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ADHESION PROPERTIES OF METALLIC AND OXIDE THIN FILMS PRODUCED BY SEVERAL METHODS C. OTTERMANN*, N. TADOKORO**, TOMITA** and K. BANGE* * Schott Glaswerke, Research Y. & Development, 6500 Mainz, Germany ** HOYA Corporation, Research & Development, Tokyo 196, Japan ABSTRACT Adhesion of Cr, Si0 2 , TiO2 and Ta 2 05 films with thicknesses between 40 nm and 380 nm has been investigated using a new scratch-test method based on a vibrating diamond micro-indenter. The oxide films are produced on different substrates by sol-gel technique (SG), reactive evaporation (RE), reactive ion plating (IP) and plasma impulse chemical vapor deposition (PICVD); Crlayers are deposited by sputtering (SP) on quartz. Large variations in adhesion are found for different coating techniques and deposition conditions, especially the substrate temperature. The adhesion can be correlated with microscopic properties in the film-substrate interface where differences are analyzed in term of hydrogen content, film growth and density. The adhesion is also connected with other macroscopic film quantities. INTRODUCTION Coatings on glass surfaces are widely used to meet various objectives. One is to improve the typical characteristics of glass as for example transparency in the visible wavelength region, high electrical insulation, low thermal expansion or rigity and hardness. Typical examples are coatings with desirable optical properties for decorative purpose or with increased wear resistance. Another new inovative application of glass is magnetic disc or photomask, where glass acts mainly as a rigid substrate. It is trivial that good adhesion is one of the most important aspects for films on glass. Indeed, inadequate adhesion promotes detachment and consequently catastrophic failure of the coated part. Therefore, the capability to evaluate the adhesion between a coating and a substrate by means of a reliable measurement is of prime interest. Additionally, it is necessary to understand the influence of the physical and chemical key properties that affect adhesion i.e. treatment of the substrates before coating, chemical reactivity of substrate and film materials and energy dissipated by the condensing particles. In this paper we present systematic investigations on metallic Cr layers and several types of oxide thin films prepared by different techniques. The adhesion of TiO2 , SiO2 and Ta2 O5 films prepared by reactive evaporation, the sol-gel process, reactive ion plating and plasma impulsed chemical vapor deposition and of Cr films produced by sputtering are examined by a novel scratch-test method, consisting of a vibrating diamond micro-indenter. The findings are correlated with changes of production parameters and differences in microscopic properties of the layers and in the film-substrate interface region. Finally the limitations of this scratch test method are indicated. Mat. Res. Soc. Symp. Proc. Vol. 308. ©1993 Materials Research Society

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EXPERIMETAL All investigated oxide films were deposited on fused silica, alkali free glass (AF 45) a