Tessera Technologies has been testing the 3D waters for several years, with the launch of its wholly owned subsidiary, Invensas, in 2011, which focused first on what they called “bridge technologies” that leverage existing packaging technologies to meet higher density requirements while waiting for full implementation of 3D ICs. In parallel, the Invensas team worked to optimize interposer and 3D integration processes like thin wafer handling, thermocompression bonding (TCB), and underfill to improve yields and lower costs. With last week’s acquisition of Ziptronix, pioneer of low-temperature direct bond technologies for 3D integration, they are diving into the deep end.

Here are the basics: Tessera acquired Ziptronix for $39M in cash. Ziptronix is a wholly owned subsidiary of Tessera, with the existing team in place. The acquisition expands on Tessera’s established advanced packaging capabilities by adding a low-temperature wafer bonding technology platform to its portfolio of interposer integration and 3D IC technologies. For Ziptronix, this means “opening up new beach fronts” for its technology as it gains access to anything Tessera has.

I have been following Invensas and Ziptronix progress separately for years. In fact, I first noticed the potential synergy between the companies in December 2013 during the 3D Architectures for Semiconductor Integration and Packaging Conference (3D ASIP). Ziptronix announced the sale of its development lab to Tezzaron, to be operated by Tezzaron’s wholly-owned subsidiary, Novati Technologies; and then Invensas announced it would be partnering with Tezzaron to provide the assembly techniques for packaging Tezzaron’s 3D IC chips. In the ensuing blog post, I mused how long will it be before there’s news that closes the loop and links Ziptronix with Invensas? Little did I know that the discussions were already well under way.

Dan Donabedian, President, CEO, ZIptronix
Craig Mitchell, President, Invensas

I spoke with Craig Mitchell, president, Invensas Corp. and Dan Donabedian, president and CEO of Ziptronix, to get the back-story, and learn more about what the companies expect to accomplish together.

According to Mitchell, Ziptronix has been on Tessera’s radar ever since the industry first started to talk about 3D ICs in the early 2000s, when the market was still years away. Discussions between Mitchell and Donabedian began around the time Ziptronix first licensed the ZiBond process to Raytheon Vision Systems in 2007. As the market was still many years away, Tessera stayed in touch with Ziptronix, and kept an eye on the market.

Last year at 3D ASIP, Mitchell said he, Paul Enquist, CTO Ziptronix, and Sitaram Arkalgud, VP of 3D Integration at Invensas chatted again about where the market was going and whether there may be something the companies can do together. The management teams met and carved out the path forward. “We’re really excited about the future,” said Mitchell.

Donabedian concurs. “As a wholly owned subsidiary, we will integrate Ziptronix technology in every way possible with Invensas and all of Tessera’s companies, and better serve the marketplaces that we could not address as a stand alone company,” he said.

So why didn’t this happen sooner? In a word – timing. Mitchell said they could see that the Ziptronix team was making great progress with both its ZiBond® direct oxide bond and DBI® hybrid bonding technologies. Sony, the world’s largest image sensor manufacturer, is a licensee for both technologies, and image sensors are predicted to be a $16B market over the next several years. Additionally, Ziptronix has made progress with RF front ends, and memory work with Tezzaron.In fact, Tezzaron’s recent accomplishment of the 8-layer logic stack used DBI. “We started to see proof points that this technology could be manufactured in high volumes, which created a significant opportunity,” said Mitchell. “We aligned our visions and it made sense to make the move now.”

The intention is to integrate Invensas’ 3D IC assembly technologies with Ziptronix’s proven platform and build off that. Ziptronix has developed a technology transfer package that we will expand upon that will help customers adopt and broadly apply the technology, explained Mitchell.

According to Donabedian, Ziptronix DBI bonding technology, which combines oxide and metal bonding, is the enabling step in the process flow for a true 3D stack that can eliminate some of the costly process steps, such as under bump metallization (UBM), TCB, and underfill. “It’s why we call Ziptronix the foundation of 3D,” he explained. “You can build on top of what we have to expand on multiple 3D fronts. That’s where this will make a difference.”

Mitchell sees Zibond and DBI as essential additions to the Invensas toolbox, alongside xFD® and Bond Via Array (BVA®) interconnect technologies, which leverage wire bonding and apply to die stacking and package-on-package (PoP) configurations, respectively. They see DBI as enabling the industry to extend beyond TCB in applications requiring finer interconnect density, as it has been demonstrated at sub-2 micron pitch, without the need for underfill.

“In most cases there are multiple tools for the job. Our objective is to provide the enabling technologies to create fully integrated 3D systems,” Mitchell explained. “Most people start with 2D devices, stack them and call it 3D. True 3D takes the whole system and the various electrical, thermal and mechanical 3D interactions into consideration. DBI, with its simplified structure, not only reduces cost, but can provide superior thermal characteristics and mechanical integrity, cleaner electrical performance, and long-term scalability when compared to thermocompression bonded die stacks with solder microbumps and underfill. We believe this represents a significant opportunity for Invensas going forward.” Mitchell sees BVA, xFD, ZiBond, and DBI living in the same world together to deliver high performance at an acceptable cost point. It’s still expensive to manufacture 3D IC–based solutions, and there is a substantial traditional packaging manufacturing infrastructure in place that will continue to be utilized for many years to come. It’s a matter of understanding the performance, functionality and cost requirements and then providing the right tools from the toolbox that best meet those needs, he explained.

What does this mean for Tezzaron Semiconductor, who already licenses both Ziptronix processes, and is in partnership with Invensas? Mitchell says it as an opportunity to work more closely with Tezzaron, reevaluate the relationship and explore the potential for further collaboration. It also makes Ziptronix processes available to Invensas when working with Tezzaron and its 3D IC products. “It just further strengthens our relationships. We intend to continue to develop and support the DBI and ZiBond processes just as we have been,” said Bob Patti, CTO, Tezzaron.

While today 3D integration is still limited to high performance computing and memory applications, ultimately, 3D IC is where the industry is headed, and both Mitchell and Donabedian see the acquisition of Ziptronix by Tessera as one piece of the puzzle that will bring advanced technology to the consumer market. ~ F.v.T

Francoise von Trapp

They call me the “Queen of 3D” because I have been following the course of…

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