Elastic and anelastic properties, internal stress and thermal expansion coefficient of cubic boron nitride films on silicon

The values of Young's modulus, internal friction, internal stress and linea r thermal expansion coefficient of c-BN thin films have been estimated from mechanical spectroscopy (vibrating-reed technique, 175 Hz-12 kHz). The thi n films were deposited by reactive sputtering onto microstructurized silico n cantilever substrates. The measured Young's modulus and thermal expansion coefficient are roughly in accordance with the few literature data on bulk material and with theoretical estimates. The internal stress of approximat ely 5 GPa is hardly affected by thermal treatments of the film up to 620 de greesC. An interesting anelastic damping peak is detected at approximately 50 degreesC (at 650 tit) with an activation energy of 0.45 eV which is sugg ested to arise from the piezo-electric and semiconducting properties of the c-BN film. (C) 2001 Elsevier Science B.V. All rights reserved.