A quick method to realize and characterize bimorph cantilevers

Abstract

Bimorph cantilever-based thermal actuators are promising for numerous applications like micro-mirror arrays, etc. This paper presents a simple technique for fabricating bimorph cantilevers using a single photolithography process and a quick optical methodology for the characterization of such structures. A bimorph combination of Al-SiO2 has been realized where SiO2 cantilevers are first realized, followed by aluminum sputtering to make the desired bimorph structure. Silicon oxide cantilevers are defined using optical photolithography, silicon area exposed by etching SiO2 in buffered oxide etch (BOE) solution and structures are released by wet bulk micro-machining of silicon in 25% TMAH solution. The cantilever deflection is characterized in a temperature range of 24-56°C using external heating and the corresponding deflections recorded via 3D imaging. A 97 μm-long cantilever tip shows a deflection of ~3.7 μm, when its temeprature changes by 32°C, corresponding to an actuation of 2.1 degrees.