Takashi Takizawa

Si through-hole interconnections filled with Au-Sn solder by molten metal suction method

This paper deals with a fabrication method of conductive through-holes in a silicon substrate, which can be applied for micro electro-mechanical system (MEMS) devices or high-density packaging. The through-holes are formed by deep reactive ion etching (DRIE) and filled with Au-Sn solder by molten metal suction method (MMSM). The MMSM we have proposed is capable of filling high aspect ratio thorough-holes with conductive metal. We could make more than 18,000 conductive through-holes, 30 /spl mu/m in diameter and 300 /spl mu/m in depth, in a 4 inches sized silicon (Si) wafer. We report the principle of the filling, the fabrication processes and the structure of the through-hole interconnections.

Conductive interconnections through thick silicon substrates for 3D packaging

We have developed key technologies to form conductive interconnections through a thick silicon substrate, which are potentially applied for 3D device fabrication or packaging of optical MEMS devices. In this paper, we demonstrate to form metal filled Through-Holes (THs) in thick Silicon (Si) substrates (t=/spl sim/500 /spl mu/m) mainly using Photo Assisted Electro-Chemical Etching (PAECE) and Molten Metal Suctioned Method (MMSM). The THs that we experimentally made with these technologies had 15 /spl mu/m in the diameter and the aspect ratio of 35. And the maximum density was 500 THs/cm/sup 2/. The dielectric breakdown voltage of the THs was more than 500 V. In the result of a radioisotope leak test using Kr-85, the leakage rate of THs between the front and the back of the substrate was lower than the detection limit (1 /spl times/ 10/sup -15/ Pa/spl middot/m/sup 3//sec.).