Mechanical properties of diamond thin films quantitative measured by means of blister test

In recent years, large strides have been achieved in understanding nucleation and growth of chemical vapour deposition diamond, but there is still not a good method of how to determine the adhesive strength, residual stress and elastic modulus of diamond thin films accurately. The blister test method which can obtain adhesive strength, elastic modulus and residual stress of thin films in a single test is very economical and practical, so it has expansive foreground in quantitative evaluation mechanical properties of thin films. By means of electron enhanced hot filament chemical vapour deposition, diamond films were deposited on silicon slice ( 100), and a free standing window sample of diamond thin films was fabricated by means of photolithography and anisotropic wet etching in this research. Using a self-designed bulge equipment, the membrane bulge height under differential pressure was measured by laser interferometry system, and then fitted by least squares procedure, the elastic modulus, residual stress and adhesive strength of diamond thin films were obtained. The apparatus of blister test is available readily and is not limited by the shape of substrate, so it can measure the mechanical properties of diamond coated tool with complicated shape, and it has provided an effective means for precisely measuring the mechanical properties of other thin films.