Chip level three-dimensional assembling of microsystems

We propose a new method of assembling three-dimensional microsystems by means of chip level electrical interconnection. Silicon dies are flip-chipped out of a silicon wafer by using ICP-RLE (inductively coupled plasma - reactive ion etching) instead of a dicing saw. Fringes of the chips are patterned into pin-shapes so that they can be vertically inserted into the micro motherboard for electrical and physical connection. The pins are coated with Cr-Au, and the contact pads are electroplated with Cu for low contact resistance (0.18 Ohm/contact). The pins are tapered in width, and assembling was easily done by manual positioning under the optical binocular microscope. This technique is a break through to the hybrid integration of various kind of micro chips independent of material or fabrication compatibility.