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Susan Rambo
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Intel's eDRAM
Susan Rambo   8/7/2014 6:32:48 PM
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I'm curious to know what engineers' opinions are of the eDRAM. Techinsights has an interesting analysis of the technology here.

resistion
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Re: Intel's eDRAM
resistion   8/7/2014 6:43:41 PM
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Power saving is limited by constant refresh of eDRAM.

Susan Rambo
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Re: Intel's eDRAM
Susan Rambo   8/7/2014 7:34:27 PM
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Interesting. The article only mentions "The eDRAM also required 1/5 of the keep-alive power compared with an SRAM device." Could you explain more about eDRAM's constant refresh and is that something that would be fixed someday, do you think?

resistion
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Re: Intel's eDRAM
resistion   8/7/2014 8:05:34 PM
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The DRAM will leak charge without a refresh, which requires power frequently every second. SRAM doesn't. Maybe SRAM doesn't sleep well enough anymore to conserve standby continuous power? What happened to near-threshold operation?

resistion
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Re: Intel's eDRAM
resistion   8/8/2014 1:17:45 PM
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My MRAM colleagues may hope to replace DRAM with MRAM but we should keep our minds open.

xys
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Re: Intel's eDRAM
xys   8/8/2014 12:09:49 AM
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What is differenceof performance between Intel's L4 cache with eDRAM and regular DDR SDRAM on motherboard?

--

xys

TanjB
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Re: Intel's eDRAM
TanjB   8/8/2014 1:42:32 AM
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Refresh seems to consume about 0.5W.  The L4 latency is about half that of DDR channels, and the bandwidth about the same as 4 DDR4.  Typical hit rate 95% (that would be remarkably good in general, but maybe the gamer market is what they aim at where locality might be better).

Not clear this is better than a Memory Cube.  But probably much cheaper.

resistion
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Re: Intel's eDRAM
resistion   8/8/2014 2:23:41 AM
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IIRC, refresh rate is lower for eDRAM, but not 0.

Violoncelles
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on chip eDRAM at IBM
Violoncelles   8/8/2014 3:03:24 AM
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IBM has been using on chip eDRAM on its chips for more than a decade .

aarunaku
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Re: on chip eDRAM at IBM
aarunaku   8/8/2014 1:10:17 PM
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@ Viollencelles,

You are absolutely right. I wonder what is different about Intel's version of eDRAM vs. IBM. Is it SOI vs. Bulk?

ssliva
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Re: on chip eDRAM at IBM
ssliva   8/8/2014 1:24:56 PM
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Intel eDRAM is MIM, not trench like IBM's.  Potentially changes the logic process's metal stack if they try to integrate it on the processor chip.  Though perhaps not.

Violoncelles
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Re: on chip eDRAM at IBM
Violoncelles   8/11/2014 6:27:42 AM
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IBM use a deep trench for the capacitor while Intel has a stacked capacitor.

ssliva
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Re: on chip eDRAM at IBM
ssliva   8/8/2014 1:21:25 PM
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Not exactly true.  The logic-process compatible eDRAM is old, but POWER4, POWER5 and POWER6 used huge MCMs where the processors were SOI and in the MCM were large L3 cache chips using a bulk logic process with eDRAM.  POWER6's discrete eDRAM L3 might've switched to SOI, and that presaged the switch to a single POWER7 chip with eDRAM on the processor die.  POWER7 launched in 2010, so not really a decade for on-processor eDRAM, though they did have the trench-eDRAM with SOI tech to do it a bit sooner.

AD2010
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what is essential about this Intel's eDRAM
AD2010   8/11/2014 9:28:42 AM
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Yes IBM was a pioneer in eDRAM and particularly TRENCH capacitor technology, which was later used by Infineon-Qimonda.  I do not know who has older patents on eDRAM, is it IBM or INTEL? And MIM Capacitor can be formed regardless of capacitor frame structure (stack or trench).

 Regarding this eDRAM device from Intel, the concept of using stacked capacitors is not new, also the idea of placing the stacked capacitor between the interconnects is not novel;

however, we are forgetting the most interesting point in this device and that is  the eDRAM cell size is way smaller than the most advanced SRAM cell and there is plenty of room to extend the memory size without changing the technology node. Also Intel claims very good retention properties of this device, which they attribute to the trigate structure of the access transistors.

I am sure Power 8 processor of IBM with 22 nm node process would be a milestone in technology but I do not know if this product is already available in the market?

 

Violoncelles
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Re: what is essential about this Intel's eDRAM
Violoncelles   8/11/2014 9:54:38 AM
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Toshiba and before it became Infineon , Siemens Semiconductor , were also using a deep Trench technology for the DRAM.

ssliva
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Re: what is essential about this Intel's eDRAM
ssliva   8/11/2014 1:07:28 PM
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@AD2010 by using my elite Googling skills, it appears that Power8 has been available since June 10 2014.


eDRAM cells are much smaller than SRAM cells in the same technology, regardless of Intel, IBM, NEC or whomever is making it.  Hopefully you aren't under the misapprehension that Intel is the first IDM to make DRAM cells smaller than SRAM.

resistion
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Re: Intel's eDRAM
resistion   8/8/2014 1:00:17 PM
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I know they were starting to use 8T SRAM, that was a sign of problems for 6T. I assume the refresh controller will only refresh cells containing data. These could be sparse.

AD2010
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Intel eDRAM vs IBM
AD2010   8/8/2014 4:33:32 PM
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hello all,

sorry for the delay, I was in vacation when the article got posted.

Here are my comments, some of them are already answered; Answering multiple comments.

1/IBM eDRAM is there from quite some time not sure if it is a decade old... IBM was a pioneer in eDRAM.

IBM latest eDRAM is 45 nm on SOI with trench technology,  while Intel eDRAM is with FinFETS and is using 22 nm technology and is based on MIM technology.

 

Intel has very old patents on eDRAM, so most likely it had this technology in their R&D sections.

It is more difficult to shrink trench technolgy. So Intel has an advantage over IBM.

 

2/ YES, Intel used 8T SRAM and will probably continue to use SRAMs along with eDRAMs but eDRAMS will take the major load as they occupy less space. Our structral anlysis reports show that Intel has used several types of SRAM but all of them take more space than eDRAM. eDRAM is a real estate saviour which is critical for future nodes.

 

We have not analyzed the eDRAM characteristics yet so cannot comment about the refresh times, the information providedin the article is taken from Intel's presentations in conferences.

 

3/ MRAM could be a potential  candidate but it is still not manufacturable ready in terms of cost effectiveness and memory size.

AD2010
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Intel eDRAM vs IBM
AD2010   8/8/2014 4:33:44 PM
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hello all,

sorry for the delay, I was in vacation when the article got posted.

Here are my comments, some of them are already answered; Answering multiple comments.

1/IBM eDRAM is there from quite some time not sure if it is a decade old... IBM was a pioneer in eDRAM.

IBM latest eDRAM is 45 nm on SOI with trench technology,  while Intel eDRAM is with FinFETS and is using 22 nm technology and is based on MIM technology.

 

Intel has very old patents on eDRAM, so most likely it had this technology in their R&D sections.

It is more difficult to shrink trench technolgy. So Intel has an advantage over IBM.

 

2/ YES, Intel used 8T SRAM and will probably continue to use SRAMs along with eDRAMs but eDRAMS will take the major load as they occupy less space. Our structral anlysis reports show that Intel has used several types of SRAM but all of them take more space than eDRAM. eDRAM is a real estate saviour which is critical for future nodes.

 

We have not analyzed the eDRAM characteristics yet so cannot comment about the refresh times, the information providedin the article is taken from Intel's presentations in conferences.

 

3/ MRAM could be a potential  candidate but it is still not manufacturable ready in terms of cost effectiveness and memory size.

rick merritt
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Re: Intel eDRAM vs IBM
rick merritt   8/8/2014 5:38:45 PM
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@AD2010: Yes, someone told me recently Intel had the early eDRAM patents but IBM was the first to really make use of the technology in a big way, perhaps licensing itsa rival's technology.

Is IBM's trench approach tied to its use of SOI?

AD2010
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IBM and SOI
AD2010   8/8/2014 5:53:50 PM
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Is IBM's trench approach tied to its use of SOI?

Most likely yes, for technologies below 45 nm node, the leakage is very high. Ultra thin SOI can reduce leakage.

IBM has lot of expertise on SOI, so if IBM continues to function as a foundry then it will use SOI.

Papers in VLSI and IEDM suggest that eventually IBM will use finFETS on SOI around 14 nm...

ssliva
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Re: Intel eDRAM vs IBM
ssliva   8/10/2014 11:58:12 PM
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SOI and trench eDRAM neither required together or mutually exclusive.


Power8 has IBM eDRAM in 22nm.

AD2010
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DRAM size and SRAM cell size
AD2010   8/11/2014 1:18:31 PM
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 I myself have worked in DRAM foundry and I know that 1 transistor and 1 capacitor  is always smaller than 6  Transistor SRAM for a given technology node.

So I am not making that mistake at all.

What I am saying is that this eDRAM cell size would correspond  to 1x SRAM cell size and the point is that SRAM is taking lot of real estate  and is not shrinking well and does not provide enough bandwidth.

 

So by switching to external DRAM from SRAM, INTEL is having lot of advantage.

Probably IBM came to the same conclusion as Intel and made eDRAM since many years. 

Paul A. Clayton
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Re: Intel eDRAM vs IBM
Paul A. Clayton   8/11/2014 6:02:07 AM
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Smaller physical size also means lower latency (at a given large capacity) despite higher cell access latency. (Welcome to the world where wire delay is increasingly important ☺)

Violoncelles
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Re: Intel eDRAM vs IBM
Violoncelles   8/11/2014 6:24:08 AM
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IBM eDRAM technology started with the 0.18um node (a Cu technology with deep trench for the capacitor). This was avalaible in year 2000 , so it's more than a decade old.

Violoncelles
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Re: Intel eDRAM vs IBM
Violoncelles   8/11/2014 9:51:09 AM
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IBM latest eDRAM is 22 nm on SOI with trench technology (for instance on POWER 8). This doesn't mean that the half pitch on the eDRAM macro is 22 nm , but the logic besides the eDRAM macro on the same chip is a 22 nm technology.



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