Test structures for a MEMS SiOx/metal process

A low-thermal budget (<450°C), multilayer CMOS compatible, surface micromachining process has been developed to fabricate IR bolometers and microswitches for RF and automatic test equipment applications. While there is a significant body of literature on the characterisation of thin films of materials for MEMS applications, the published work deals mainly with films or structures of one material. This paper describes the work undertaken to characterise the elastic modulus and residual stress in films of individual dielectric and metal layers and results on composites of dielectric and metal. This paper considers the results obtained for structures composed of oxide, oxide-aluminium/silicon-titanium, oxide-titanium and titanium layers. Material properties are measured using cantilever and fixed beam arrays fabricated in oxide, metal and composite metal/oxide films. The parameters extracted are residual stress, stress gradient and elastic modulus.