[21p-P17-1~26] 13.4 Si wafer processing /Si based thin film /MEMS/Integration technology

▼ [21p-P17-20] Application of Supercritical Carbon Dioxide in Electroplating of Gold Materials Used in MEMS Devices

〇(D)Haochun Tang¹, Chun-Yi Chen^1,2, Tso-Fu Mark Chang^1,2, Katsuyuki Machida^1,2,3, Daisuke Yamane^1,2, Kazuya Masu^1,2, Masato Sone^1,2 (1.P&I Lab. Tokyo Tech, 2.CREST JST, 3.NTT AT Corp.)

Keywords:MEMS,Gold electroplating,Supercritical carbon dioxide

Recently, gold materials have attracted much attention and are commonly used in micro-electrical-mechanical systems (MEMS) devices due to their excellent electrical and mechanical properties. Electroplating (EP) is often used in preparation of the gold materials because the morphology, crystal structure, and deposition rate of the deposited gold materials could be easily controlled by varying the EP parameters. On the other hand, mechanical strength of gold materials is relatively low when compared with other metallic materials, which is always concern in practical applications in MEMS. In previous studies, grain refinement effect was observed in the nickel films prepared by the EP with electrolyte containing supercritical carbon dioxide (scCO₂), which then leads to a significant enhancement in the mechanical strength due to Hall-Petch relationship. ScCO₂ is CO₂ at temperature and pressure above its critical point, which are 31.1°C and 7.38 MPa. In this work, feasibility of the EP with the scCO₂ for preparation of gold films would be evaluated and reported.