A VIA STRUCTURE

摘要

A via structure is obtained by etching a through-hole in a substrate on the via location and placing transmission lines on declining or sloping sidewalls of the hole. The lines continue to conductors on the other surface of the substrate through vias located in a free portion of a thin film structure at the bottom side of the substrate. The free portion is so strong and large, that several vias can be made therein for connection to a plurality of parallel lines forming e.g. a bus structure. The large free portion can be additionally supported by a thick support layer applied on top of the layers in the hole. By applying an isolated ground plane and a dielectric layer between the substrate and the transmission lines, the transmission lines on the sloping sidewalls of the via hole structure can be made impedance matched. The sloping sidewalls of the via hole can easily be obtained using a V-groove etch for a monocrystalline Si-substrate. The via structure obtained is especially well suited for data transmission buses, which do not need to reduce their transmission line density through the via structure.