DALSA semiconductor has said that tests undertaken on the eG ViaCoat process from Alchimer S.A. enabled the MEMS device producer to fabricate conformal copper seed layers on through-silicon via structures (TSVs), while overcoming the inherent problems of reentrant TSV, using the Bosch deep reactive ion etching (DRIE) processes.
"For years, DALSA Semiconductor has fabricated low cost MEMS products using via-first TSV for its 3D integration technologies,” commented Luc Ouellet, VP of Technology Development at DALSA Semiconductor. “With Alchimer’s copper-based eG ViaCoat approach we can support consumer MEMS products with faster operating frequencies and higher power density with even lower resistance and higher thermal dissipation through TSV. Alchimer's approach for TSV is a strategic technology allowing us to mass produce MEMS devices in cost-sensitive markets."
A reentrant TSV with a smaller entry size at the top than at the bottom causes filling problems for conventional copper deposition techniques. The Bosch DRIE process is still preferred as it is regarded as a cheaper alternative for high-volume, low-cost production. Alchimer said that it was also successful in demonstrating the subsequent void-free copper fill on deep reentrant TSV structures for DALSA.