Tensile Properties of Amorphous Diamond Films

Q$~{ The strength and modulus of amorphous diamond, a new materhil for surface micromachined MEMS and sensors, was tested in uniaxial tension by pulling laterally with a fl t tipped diamond in a nanoindenter. Several sample designs were attempted. Of those, only the single layer specimen with a 1 by 2 pm gage cross section and a fixed end rigidly attached to the substrate was successful. Tensile load was calculated by resolving the measured lateral and normal forces into the applied tensile force and frictional losses. Displacement was corrected for machine compliance using the differential stiffness method. Post-mortem examination of the samples was performed to document the failure mode. The load-displacement data from those samples that failed in the gage section was converted to stress-strain curves using carefully measured gage cross section dimensions. Mean fracture strength was found to be 8.5 & 1.4 GPa and the modulus was 831 &94 GPa. Tensile results are compared to hardness and modulus measurements made using a nanoindenter.