by Pete Singer, editor-in-chief
May 19, 2011 – At this year’s The ConFab, held May 15-18, in Las Vegas Nevada, a recurring theme was that 3D integration shows tremendous promise, particularly with many fabless companies, yet many barriers remain. "We firmly believe 3D will provide a better form factor and better system level performance," said Nick Yu, VP of technology development at Qualcomm. He believes that smart phones and the demand they create for wide I/O memory stacked on logic could be the key enabler for through-silicon via (TSV) technology. "We really think it can bring the best of all worlds into your mobile handset," he said. "We think the smart phone space is really the right application for 3D TSV stacking." Growth in this market drives a lot of volume, which will drive down the cost and drive adoption, thus justifying the industry’s investment.
How soon does all this happen? Yu said Qualcomm is pushing for implementation by 2013, and that over the last four years they have already completed a lot of engineering work with the supply chain and demonstrated the concept. It’s a little bit of a "chicken-and-egg" situation, he noted, because a driver product is needed to acquire process learning and drive the product ramp, but there are "no real show-stopper or intrinsic technical issues," he said.
Wide I/O memory on logic provides significantly more bandwidth. The memory industry’s view is that as smart phones blur the lines between tablets and hand laptops, demand for memory bandwidth will be nearly insatiable. To enable that, standards are needed and JEDEC is going to finish the wide memory standardization by the end of this year. Memory vendors will have parts sampling in 2012, all targeting end-product going to market by 2013, according to Yu.
What’s not quite there yet, though, according to Yu and other presenters at The ConFab, is the 3D supply chain. "3D really ties a lot of other players together and it has this really complicated cobweb type of relationship," he said. "It is, in a sense, quite disruptive to the supply chain. That’s certainly one of the major challenges for a fabless company like Qualcomm. We’ve been spending a lot of time and resources to work with the supply chain for the last four years on this."
Qualcomm has a clear vision of what the product looks like, and that the architecture has already been optimized, Yu explained. The next step is to implement that in the manufacturing process — and therein lies the rub. "I think there are some integration challenges out there that we haven’t quite fully resolved," he said. "We need some sort of standards and conventions between the supply chain hand-offs." One example is the quality of a stack of known good die (KGD). "If we have a stack of memory, what is meant by a known good stack of memory? Who’s going to be responsible for the test, and what’s the quality of it?" All these discussions need to happen between the supply chain partners, with "huge implications" for their balance sheets, he noted.
Other business model questions: Who ultimately owns the dies? Who owns the inventory? And does the "pass-through" business model work? How is it going to be funded? Who owns the integration process in the end, and who owns yield? There are no easy answers.
The good news is that companies such as Qualcomm appear to be committed to making it work. "We really thought about all those challenges and we’ve set out to work with the industry, leveraging some of the standards bodies and really pulling together different players in the supply chain to work through that," Yu said. "There’s a lot of good will and intent in the industry, but I don’t think there’s enough leadership." Certainly SEMATECH has a strong program underway, but like everything else, it takes people like YOU to get involved.