By Dr. Phil Garrou, Contributing Editor

Before we take a look at the recent SEMI European 3D Summit, a little news on the licensing front.

OmniVision Signs License Agreement with Ziptronix

Well, actually Ziptronix as we all know by now was acquired by Invensas, a division of Tessera, in the fall of 2015.[see IFTLE 253 “China Inc Seeks to Acquire GF; Tessera Acquires Ziptronix … “]

But now, Tessera has changed its name (as of Feb 22^nd) to Xperi (link).

The key issue here is that Ziptronix owns patents for direct oxide bonding and copper/oxide so called hybrid bonding ( they call tehse technologies Zibond and DBI). This technology that is being used extensively in the CMOS image sensor (CIS) market and was licensed to Sony, the accepted world leaded in CIS in 2011 [link]

There has been ongoing litigation with Omnivision over violation of the Ziptronix patents since 2010. [link]

A few weeks ago that litigation was resolved when Tessera announced that its subsidiary Ziptronix had reached a licensing agreement with OmniVision. In turn, the outstanding litigation by Ziptronix against OmniVision and TSMC has been dismissed.[link]

FYI, the Ziptronix IP has also been licensed by aerospace leaders Raytheon, Teledyne and supplier Novati.

2017 SEMI European 3D Summit

The Annual SEMI European 3D Summit took place in late January in Grenoble France. For the next few weeks we’ll be taking a look at some of the interesting presentations that were given there.

Meyer – Infineon

Thorsten Meyer, one of the early players in FOWLP used a great simple slide to show the advantages of FOWLP over 2.5D interposers for select lower density cases. Basically the FOWLP (like eWLB) can reach the 200um pitch directly without the high cost silicon interposer. When this can generate enough IO for your application, this could be the most economical solution.

Wolf – Fraunhoffer Institutes

Juergen Wolf examined the technologies available in the Fraunhoffer institutes for “Heterogeneous Integration for 3D systems.”

Of interest is their work with Osram and Infineon to develop GaN LED chips n Silicon drivers as shown below.

Wolf also announced that Fraunhoffer is working with Ziptronix on their DBI bonding technology and showed a 96% yield on DBI test vehicles.

• DBI is an extension of Ziptronix’ ZiBond technology that allows an interconnect pitch of less than 10-microns, and accommodates 1.5 million connections per square centimeter.
• The process uses advanced tools to planarize the wafer surface and allows hermetic bonding SiO2/Cu at low temperatures (300°C).
• Technology is jointly developed by Invensas and IZM ASSID & partners

Also of interest was their interposer roadmap which included not only TSV but also integrated passives, embedded chips and fluid cooling channels down the road.

Gen 1 Interposer = TSV, multi layer redistribution(RDL)

Gen 2 Interposer = + integrated passive devices

Gen 3 Interposer = + embedded active devices and/or MEMS

Gen 4 Interposer = + integrated optical & electrical interconnects

Gen 5 Interposer = + active cooling (e.g. fluid channels)

Groothuis – Samtec

Steve Groothuis discussed the use of glass interposers. Samtec acquired Triton Microtech (a glass interposer startup) last year. Their approach is to use thin fil RDL with thick film filled vias. “Samtec Microelectronics will be processing borosilicate glass, fused silica, quartz, zirconia, and sapphire wafers and eventually panels for cost and scaling.”

While they acknowledge that the glass interposer platform has not become mainstream yet, they contend that glass interposers are a strong candidate to be used in RF applications because of superior electrical insulation, low dielectric constant, high hermeticity, low warping, and high resistance to corrosion. Their design rules are shown below.

Samtec shows copper diffusion data and concludes “No diffusion of Cu into the glass –No need for a barrier layer along sidewall,” this leaves me somewhat puzzled since the last time I checked glass was SiO2 and we now Cu diffuses like a rabbit in SiO2. Maybe the expts were not run under bias?

They conclude that Samtec will work with customers in various areas of Glass Core Technology for prototyping, low-volume production, and paths to high-volume manufacturing.

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