Determination of Young's modulus of electroplated nickel-iron (Ni/Fe) and micro-machined Si thin films by the balance method

This paper presents a simple method to measure Young's moduli of thin films shaped into micro-cantilever beams (MCBs). Young's moduli of electroplated Ni/Fe thin films and 〈1 1 0〉-oriented silicon have been determined in this paper based on this method. First, the principle of the balance method is introduced and the systematic error of this set-up is analyzed. Then, using photoresist AZ 9620 as the electroplating molds, free-standing low stress Ni/Fe cantilever beams (CBs) with different Ni/Fe mole ratios were prepared by UV-LIGA technology. Micro silicon CBs also were fabricated by the standard wet-etching process. The experiment results show that the Young's modulus of electroplated Ni/Fe films is associated with the process conditions. The measured Young's moduli of Ni/Fe films change greatly, from 101GN/m² (Ni 43 wt.%, Fe 57 wt.%) to 186GN/m² (Ni 64 wt.%, Fe 36 wt.%). The average value for (1 1 0) silicon CBs is about 164 GN/m², which is in good agreement with previously published data. This method that has been developed is simple, non-destructive and universal and can be used for in situ measurement with all kinds of micro-machined components.