Micro tube insertion into indium, copper and other materials for 3D applications

The viability of inter-strata low pitch vertical interconnection technologies is mandatory for 3D applications. In order to increase the connection complexity and to reach a 10μm or even smaller interconnection pitch, a new room-temperature insertion technology has been proposed and developed using micro tubes as inserts [1]. In the present work, we study the load required to obtain a full and efficient insertion of a single micro tube into indium, copper or other materials. We use a modified nanoindenter with a very accurate load and displacement control, to qualify the insertion process. The nature of the couple constituted by the insert and the soft metal is of major importance. Our study focuses on two specific parameters: Mechanical properties of the soft metal; Combined geometries of the soft metal and the insert. Thanks to this study, we can give the best conditions to improve insertion load and time for different couple. Finally, some first chips hybridizations are performed and tested mechanically and electrically to validate our work.