21 November 2017
ClassOne slashes via liner plating costs for compound semiconductors
ClassOne Technology of Kalispell, MT, USA (which manufactures Solstice electroplating systems for ≤200mm wafers), has unveiled a new plating technique that is said to provide significant cost reductions for compound semiconductor manufacturers who use gold plated vias.
“We have compound semiconductor customers that use gold for via liners who are switching to copper to save money,” says president Kevin Witt. “When they implement the copper plating on our Solstice ECD system with the ClassOne CopperMax chamber, dramatic cost reductions are obtained – on the order of 70% lower metallization cost compared with their previous approach,” he reckons.
The new savings result not just from replacing the bulk of the gold with copper but also from the additional copper-plating economies made possible by the unique CopperMax chamber design, says Witt. Consumables have been the largest single cost factor in copper plating, he adds, because the process required large volumes of expensive organic additives over the lifetime of the bath. Now, by employing a cation-exchange membrane to separate anolyte from catholyte, the CopperMax chamber effectively isolates additives from the anode, drastically reducing additive depletion and hence usage. Also, since the CopperMax bath remains clean much longer, bath life is extended by 15-20x, it is reckoned, resulting in increased uptime and throughput.
CopperMax also reduces copper anode expenses. Instead of solid machined copper material, the new chamber can use less expensive bulk anode pellets, cutting anode costs by over 50%. Plus, since the pellets provide much greater surface area, the maximum plating rates can be increased.
In addition to the process improvements, the net result is a significant reduction in cost per wafer: compared with previous copper processes, the CopperMax chamber reduces additive consumption by over 95%, resulting in an overall cost-of-ownership reduction of almost 50%, it is estimated. Also, for users who switch from gold to copper via liners and do the plating on a Solstice system with CopperMax, the costs are cut by about 70%.