Low Cost Via-Hole Filling Process Using Powder and Solder

Abstract This study proposed a noble process to fabricate TSV (Through Silicon Via) structure which has lower cost, shorter production time,and more simple fabrication process than plating method. In order to produce the via holes, the Si wafer was etched by a DRIE (DeepReactive Ion Etching) process. The via hole was 100
um in diameter and 400
um in depth. A dielectric layer of SiO 2 was formed bythermal oxidation on the front side wafer and via hole side wall. An adhesion layer of Ti and a seed layer of Au were deposited. Solderingprocess was applied to fill the via holes with solder paste and metal powder. When the solder paste was used as via hole metal line,sintering state and electrical properties were excellent. However, electrical connection was poor due to occurrence of many voids. In thecase of metal powder, voids were reduced but sintering state and electrical properties were bad. We tried the via hole filling process byusing mixing solder paste and metal powder. As a consequence, it was confirmed that mixing rate of solder paste (4) : metal powder (3)was excellent electrical characteristics.