Masato Sone
Tokyo Institute of Technology, Japan
Title: Integration of biocompatible MEMS by gold electrodeposition using supercritical carbon dioxide
Biography
Biography: Masato Sone
Abstract
The flexible properties of polymeric material make bio-MEMS promising candidates for the next generation of micro devices. However there have been many difficulties to overcome in fabrication process. Supercritical carbon dioxide (sc-CO2) is generally viewed as a replacement for harmful organic solvents used in extractions, separations, chemical reactions, molding, and many other applications because CO2 is non-polar and the tunable physical properties between a gas and a liquid. Especially for application of sc-CO2 in fine wiring technology, transfer of materials into and out of fine nano-space can be improved to allow proper cleaning and complete filling of the nano-spaces. Thus we have studied an application of sc-CO2 into integration of bio-compatible MEMS. We examined sc-CO2 for washing of photoresist pattern on substrate and completed washing the pattern with strengthening the adhesion. We have also proposed a washing process using emulsion of sc-CO2 in water for eliminating the resist pattern from the substrate. We now have studied metalizing of gold on polyimide, which is composed of catalyzation process on/into polymer using sc-CO2 of Pd-organic complex and electroless plating using sc-CO2 emulsion (ELP-SCE), which is composed of an aqueous electrolyte, sc-CO2, and a surfactant. ELP-SCE enabled the penetration of Pd into deep-inside of polymer. So Pd seed-layer can be deposited on polyimide. We also have studied gold electroplating method using sc-CO2 emulsion (EP-SCE). Metal film obtained by this technique was uniform and without pinhole, because sc-CO2 has low viscosity and compatibility of hydrogen. Thus, we have proposed and examined a void-free gold wiring on the Pd seed layers/polyimide. This method is applicable into bio-compatible MEMS.