A few months ago, Andreas Fischer, of the Microsystem Technology Laboratory School of Electrical Engineering Royal Institute of Technology, Stockholm, Sweden, contacted me to tell me about a novel process for filling TSVs that he had been working on from first proof of concept in August 2008, as part of his doctoral work, and with strategic support provided by KTH Innovaton.
The process veers considerably from traditional electrochemical deposition, and instead uses magnetic self-assembly of ferromagnetic nickel rods inside etched through silicon via holes. The intention of this work was to address reliability problems caused by void-formation during the metallization process and/or thermo-mechanical stress. According to Fischer, this TSV fabrication method enables through-wafer vias with high aspect ratios and superior electrical characteristics. Additionally, he says it eliminates issues common to conventional TSV fabrication approaches, such as the metal deposition and via insulation and has the potential to reduce production costs of HAR TSVs used in such applications as interposers, MEMS and RF applications. The technology is covered by patent applications.
Over the past year, Fischer has delivered presentations on his findings at such prestigious conference as IEEE MEMS 2011 in Cancun Mexico and at ECTC 2012, in San Diego to gauge the level of interest in the industry, and to get feedback from the technology community. The next logical step is to engage with industrial partners to further the development of this process, with the long-range goal of bringing it to manufacturing.
Interested in learning more? Check out this web page, Development of Magnetically Assembled High Aspect Ratio TSVs An Industrial Partnership Opportunity. If you think this is something your company would be interested in becoming involved in, please drop me a line at francoise@3dincites.com or better yet, flag me down this week at SEMICON West and we can talk more about it. ~F.v.T.
