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3D Qualcomm SoC Testing on Horizon

Adding unlimited layers sans TSVs
3/31/2015 09:36 AM EDT
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R_Colin_Johnson
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Re: Qualcomm going for monolithic 3D !
R_Colin_Johnson   4/2/2015 8:19:50 PM
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Yes, you are right about MEMS/CMOS integration only possible with wirebonding or TSVs today. We'll see what tomorrow brings :)

docdivakar
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Re: Qualcomm going for monolithic 3D !
docdivakar   4/2/2015 4:45:32 PM
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@Colin: time and time again, I invoke Samuel Longhorn Clemens, rumors of his demise were greatly exaggerated during his life time! The same goes true for TSVs! The heterogeneous stacking world is alive and well... thanks to advances made by companies like InvenSense, it is the only way to make MEMS-CMOS integration possible.

MP Divakar

docdivakar
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Re: Qualcomm going for monolithic 3D !
docdivakar   4/2/2015 4:37:46 PM
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@chipmonk0 reg your points on TSVs being only in the periphery for devices like Sony's, those were the early versions of TSVs for stacking where a safer route was taken to realize the products. How ever, it is well-known that WideIO memory products that use interior TSVs are in the Active Area, Samsung has them in production.

I can draw some parallel between interior TSVs vs. wirebonding over active area from nearly 12 years ago (many power devices like TI's Swift switches were using them). I think the lessons learned from reliability studies were definitely helpful for TSVs.

MP Divakar

R_Colin_Johnson
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Re: Qualcomm going for monolithic 3D !
R_Colin_Johnson   4/2/2015 2:06:11 PM
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Thanks for the inside info. I had not heard these numbers from the teardown specialists. Perhaps TSVs will have a place in the future, but still think they will be a hard sell against monolythic 3-D with normal vias. Time will tell.

R_Colin_Johnson
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Re: 2016 or not?
R_Colin_Johnson   4/2/2015 2:03:49 PM
Thanks for you interest. I personally believe that Leti will not use TSVs for anything anymore, but is concentrating all their efforts on monolithic 3-D with normal vias. Also I believe that Leti will license the technology to CMOS foundries for Qualcomm and other high-volume manufacturers. We won't have to wait long to see, according to Qualcomm.

R_Colin_Johnson
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Re: Qualcomm going for monolithic 3D !
R_Colin_Johnson   4/2/2015 1:59:56 PM
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Thanks for the tips on TSVs. I personally believe the TSVs are dead. Qualcomm is not using them. Samsung is not using them for 3-D NAND. Monolithic 3-D using regular vias is the future of 3-D chips. Thanks again.

chipmonk0
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Re: Qualcomm going for monolithic 3D !
chipmonk0   4/2/2015 12:49:04 PM
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this is not exactly news, though it may be so for the Blogosphere !

at least since late 2013, SONY has been shipping ( e,g. to Apple ) those image sensors that you now mention which use TSVs to partition the image sensor made at a older node from the processor done at 45 nm or lower and thus avoid poor old SONY having to plunk down cash for a newish Fab.

Instead SONY went for integration at the package level in a prudent way. By using the TSVs in a 2 die stack they were able to maintain / improve the electrical performance of their BSI image chip module.  

But dear friend those TSVs are all peripheral in order to avoid the unnecessary complication ( in SONY's case ) of packaging stress effects ( CPI ) on transistor perf.

When DRAM chips are stacked using TSVs in the Active Area ( i,e not just peripheral TSVs  lke SONY imager but all over the die or even in a central Wide I/O like format ), stress along with accumulated heat / non uniform temperature distribution complicate device performance ( switching time and refresh reqmt.s )

And when those Memory chips are stacked using TSVs, but in a peripheral arrangement to isolate stress, the parasitic effects of the longer interconnects ( same as in current WB ed stacks ) affect the bandwidh improvement touted for TSVs.

chipmonk0
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Re: 2016 or not?
chipmonk0   4/2/2015 12:28:56 PM
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Where would a fabless wonder like QCOMM get its 3d chips, stacking transistors for SoC and DRAM on a single die made by 2016 ?

Samsung is already shipping 3d NAND and Micron is coming up behind them. Will either of these 2 ( especially Samsung which has dumped QCOMM SoCs for its own Exynos ) do the R&D for just QC instead of broader gains ?

So at this time only LETI would be the likely Foundry for QC.

But what is the credibility of LETI's forecast of even 2018 ? Given their track record for TSV based 3d stacks ? 

The most that LETI ever came up with for WORKING Processor / Memory stacks using TSVs was a single DRAM chip ( not a whole stack of 'em ) face to face attached to a purpose designed SoC ( Network Controller ) with TSVs that was then packaged to a substrate by flip chip.

Will be eager to hear of any recent developments at LETI on TSV based full stacks.

PFWerbaneth
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Re: Qualcomm going for monolithic 3D !
PFWerbaneth   4/2/2015 10:02:36 AM
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Regarding whether stacked chips with TSV connections are PowerPoint engineering or nor, I would like to report sightings in the wild of BI CMOS Image Sensors stacked on control logic using TSVs as found in both front and rear cameras on the Apple iPhone 6 family, of which 75 million units were shipped in Q4 2014. That's 150 million 3D IC TSV-stacked components for just one handset maker for just one component, a camera, in just one quarter.

R_Colin_Johnson
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2016 or not?
R_Colin_Johnson   4/1/2015 5:49:16 PM
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Qualcomm is hoping for prototypes by 2016, but Leti, whose very similar work it is funding, along with IBM and others, are predicting 2017 or 2018, which I believe is more realistic. In any case Qualcomm will probably be first out of the gate.

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