An electrically isolated through-wafer via hole, covered by a membrane, has been realized by standard integrated circuits processes together with deep silicon etching. The deep silicon etching was performed by the Bosch silicon etch process in a Plasma-Therm etch system. The via structures were made in double-sided polished 300 mum thick silicon wafers and had widths down to 20 mum, which correspond to an aspect ratio of 15. The fact that the via structures are electrically isolated makes them a suitable start-point to realize interconnections through a wafer. Furthermore, the application field of the via structure is broadened by the flexibility in the design of the structure, which makes it possible to apply an almost arbitrary membrane material onto the via structure at the end of the process. [References: 15]
展开▼
