ASE licenses K&S technology to produce advanced copper wafer BGA packages

March 6, 2001–Willow Grove, Pennsylvania–Kulicke & Soffa Industries Inc. (K&S) announced today that Advanced Semiconductor Engineering Inc. (ASE) has signed an agreement to purchase a technology license and specialized equipment for K&S’s proprietary OP2 Oxidation Prevention Process, which is used to manufacture copper ICs.

ASE will use the technology, which combines a patent-pending process and specialized equipment, to produce advanced copper wafer ball grid array (BGA) packages at its Kaohsiung, Taiwan, assembly facility.

OP2 is the first commercially available technology for bonding of gold wire, routinely used in ball bonding processes, directly to a copper device, according to K&S Program Director Michael Sheaffer. “Copper is extremely difficult to wire bond, because of the way it oxidizes,” Sheaffer explains. “Until now, the only way to achieve reliable results was to add aluminum or other metal layers over the bond pads–increasing wafer fabrication cost by as much as $100 per wafer. The comparative cost of the OP2 process is a fraction of that amount. We believe our customers will embrace this alternative as copper continues to replace aluminum in high-performance packages.”

“Extensive reliability testing at ASE has shown that OP2 provides excellent results, and we expect the process to provide significant cost benefits to our customers,” says ASE Vice President of Research & Development J.J. Lee. “The process will enable us to combine the performance of copper die with the economics of wire bonding to meet many of our customers’ requirements for high-end, fine-pitch packages.”

OP2 adds a cluster tool process in the assembly factory just prior to wafer dicing. The tool removes native oxides from the copper wafer and protects it from further oxide growth during the dicing, die attach, curing, and wire bonding steps of semiconductor assembly interconnect. This patent-pending process is designed to emulate the mechanisms that are characteristic of traditional gold wire bonding to an aluminum bond pad. Extensive metallurgical analysis has shown that the dynamics of conventional gold-to-aluminum ball bonding are maintained, even though the wafer material is different.


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