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alex_m1
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Why not 22nm?
alex_m1   5/19/2014 10:07:32 AM
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Are there efforts to go down to single patterning 22nm like intel, and if not why ? And how does 28nm fd-soi compares to 22nm with regards to power consumption ?

Gondalf
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Re: Why not 22nm?
Gondalf   5/19/2014 4:17:33 PM
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Strange enough Intel (and TSMC) are thinking the opposite about FD-Soi.

On Intel 22nm the FinFet adoption only charge 2-3% of more costs, FD-Soi was not utilized because means a strong 10% charge over bulk.

The real story is that Samsung has not a good experience in processes for CPUs, GPUs or SOCs. Samsung has never developed something of exciting in this segment, it's processes for SOCs are licensed from Common Plataform (IBM mainly). in this moment Samsung is in crisis because IBM is out of the game and GloFo has not money to develop anything.

The more easy street to gain a bit of power reduction is to license (again) a process from another Company out of Common Plataform...

Samsung is late on 20nm bulk and likely is VERY late in FinFet, so an expensive FD-Soi could be an interim solution for it's SOCs. Too bad Samsung is losing the shrink and this will rise the costs even more. Too bad "money" is not enough to gain proof in silicon science, it needs "men" and their experience, Samsung has not them.

I can see only two companies able to gain a lot of momentum in silicon industry in the near future: Intel and TSMC.... all others have not the experience to face the upcoming very difficoult silicon nodes.

AKH0
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Re: Why not 22nm?
AKH0   5/19/2014 4:27:44 PM
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Did Intel fabricate either bulk 22nm to proove FinFET was only 2-3% cost addrer? Did they run FDSOI to see it is 10% cost addrer? No, it was all powerpoint. Same as the famous chart that claimed 37% performance advantage coming from FinFET with no silicon data to back it up -- yes, they actually showed ring ocsilator data at VLSI to support that claim, but I am sure they wish they didn't.

rick merritt
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Re: Why not 22nm?
rick merritt   5/19/2014 9:03:49 PM
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@Gondalf: An interesting alternate take on the news.

etienneazerty
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Re: Why not 22nm?
etienneazerty   5/20/2014 3:47:39 PM
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This post is so biased it is difficult to believe.

Saying Samsung is unable to shrink silicon technology when they are leading DRAM and Flash scaling is a joke. Not to mention there lead in display technology. But you may not consider this as "silicon".

Playing the FD-SOI card has nothing to do with failing FinFET. It has specific attribute specially for SOCs and low power technology. And this is where the future of silicon technology will be.

Before considering the fail of FinFET integration within Samsung, just wait by the end of the year...

AKH0
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Re: Why not 22nm?
AKH0   5/19/2014 4:31:42 PM
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In principle it is possible, but it comes at the expense of less design flexibility. The gate and metal pitch at 28nm allows bidirectional poly and metal, whereas Intel's 22nm is unidirectional. A bidirectional M1 is almost equal to 2 layers of unidirectional metal for most designs.

OtisTD
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Re: Why not 22nm?
OtisTD   5/20/2014 1:13:27 PM
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Intel used double patterning at 22nm.

 

It would depend on the design, but 28nm FDSOI should be pretty comparable to 22nm bulk planar (maybe even better?) from a power vs. performance standpoint.  Die size will be bigger, which normally means higher cost, but in this case that isn't so clear.  Based on the releases so far the argument in favor of the 28nm FDSOI is that for medium-low TAM products 28nm cost is a sweet spot, there is minimal re-design/re-optimization cost to go to FDSOI, so that offsets the additional substrate cost.  The process flow might be a little simpler with FDSOI than with 28nm bulk planar and certainly simpler than 22nm, further offsetting the cost.  I haven't seen any indication yet that they will introduce additional body biasing techniques for this 28nm node, but they could and that would further reduce power for some products.  Keep in mind Intel has high TAM products that require very high performance- FinFET/TriGate has an advantage there.

 

AKH0
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Re: Why not 22nm?
AKH0   5/20/2014 2:25:28 PM
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@OtisTD: Actually, 28nm FDSOI comes with full body bias capability and it is one of its selling points. While people might consider body bias as an extra design burden, many companies - including Samsung in their 28nm bulk - already used static body bias. Dynamic body bias is a bit more involved but it has been done in the past (TI 45nm e.g).

OtisTD
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Re: Why not 22nm?
OtisTD   5/20/2014 2:41:07 PM
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@ AKH0

When I said, I hadn't seen any announcement of "additional body biasing techniques" I meant in addition to what is already available for 28nm bulk.  Are you saying that they are offering dynamic body biasing (and where did you see that)?  Or just that static body biasing will continue to be offered- which was my intention/understanding.  Sorry if I wasn't clear, but I didn't think it was necessary to go into detail.  Basically from my understanding they will use the same masks as much as possible and directly port it over FDSOI without adding any additional performance knobs like dynamic biasing.

AKH0
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Re: Why not 22nm?
AKH0   5/20/2014 4:17:15 PM
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@OtisTD: Thanks for clarifying. The 28FDSOI is using the flip-well concept (n-well under NFET and p-well under PFET) for LVT devices. RVT is same as bulk design. This allows LVT devices to be forward biased to 1V or maybe more, which is not possible in bulk. If you already have a 28nm bulk design, for static body bias, you can probably just change the well masks, drop the Vt adjust masks, and add the No SOI mask (for diodes, etc).

As far as I know, ST has already implemented dynamic body bias. While it needs some redesign and proper system and software, it is not that different from DVFS to implement. Actually it is a bit simpler because wells do not draw as much current as Vdd does, so charge pumps are enough and routing is easier.

HJ88
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Cost Per Gate is a Critical Factor
HJ88   5/20/2014 6:39:59 PM
The cost for 100M gates of a product made with 14nm FinFET (including 16nm FF+) will range from $1.38 to $1.53 in Q4/2016.

28nm HPC cost per gate will be $0.97 for 100M gates (28nm fab partly depreciated).

For 28nm FD SOI (even allowing for the high cost of the substrate), the cost will be $0.92 for high volume manufacturer. Margins have to be added to get wafer prices from the foundry vendors.

For the high volume applications, cost is the most critical factor followed by power consumption.

The reality is that TSMC and Samsung are very close in their road maps for trying to ramp 16nm FF+ and 14nm FF. While process control is a key factor in bringing up FF products, another critical factor is DFM and impact on parametric yields. It is low parametric yields that have delayed the ramp-up of 14nm FF to date.

Cost per gate is a critical factor, and longer term cost and price do have a relationship.

AKH0
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Re: 28nm FD-SOI
AKH0   7/13/2014 1:32:21 AM
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Dear Sang Kim, I am not sure what you mean by punch through. There is no leakage path other than the thin channel which is fully controlled by the top gate. I-V characteristics of FDSOI devices have been published in major conferences and there is no sign of degraded electrostatic as you claim. As far as the mobility degradation in thin SOI is concerned, mobility is already hit by high-k gate stack and yet every body is using it. As far as a device delivers the performance why should I care if mobility is higher or lower. Let numbers speak for themselves. We have shown 1.65 mA/um at 1V and 100nA/um for NFET which as far as I know is the highest DC performance ever reported. For PFET drive current is 1.4 mA/um which is again record high. And these are devices at pitch with all parasitic resistances of real technology. And unlike FinFET camp there is no cheating in drive current normalization. I do not want to brag about DC performance as there are many other factors determining circuit performance. But if you are concerned about DC performance please take a moment and review papers in the past few IEDM and VLSI.

michigan0
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28nm FD-SOI
michigan0   7/13/2014 1:48:51 AM
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Sang kim

 

Handel Jones says 28nm FD-SOI is an alternate option 

for low leakage, high yields and high performance superior 

to 28nm bulk technology. Consequently, Samsung

can support low leakage products with its 28nm FD-SOI.

look at the real issues with FD-SOI. My first question is why 

28nm FD-SOI is still not manufactured today by major 

semiconductor companies because 28nm bulk is manufactured 

for several years by major semiconductor companies today 

such as Intel, TSMC, Samsung and others. 

 

In un-doped FD-SOI channel here, it is possible for drain depletion to extend with large Vdd(1V) to source without inversion. I call this effect punch-through. Therefore, punch-through failure can occur in un-doped FD-SOI. On the other hand, the drain induced barrier lowering or DIBL leakage current most likely occurs also in un-doped FD-SOI. In order to prevent such DIBL leakage current it is imperative to have an ultra thin SOI channel layer between source and drain so that the drain field can't easily penetrate the ultra thin SOI channel. How thin the ultra thin SOI thickness has to be in order to stop DIBL leakage current? It depends on the channel or gate length, Lg. For shorter Lg, a thinner SOI  channel is required. This is the most critical issue for FD-SOI.

 

For 28nm FD-SOI a 7nm thin SOI channel thickness is required to stop DIBL leakage current. However, the transistor performance becomes significantly degraded due to the transistor mobility degradation because of scattering of charge carriers at the top gate oxide surface and at the bottom SOI surface in the 7nm thin SOI channel. As a result, even if 28nm FD-SOI were manufactured today, it wouldn't be superior to 28nm bulk in terms of transistor performance and manufacturing costs due to significantly higher SOI wafer costs. These are the major reasons why the 28nm FD-SOI is not manufactured today.

The other major issue with FD-SOI is its scalerbility. For

20/22nm FD-SOI a 4~5nm SOI channel thickness is required

to stop DIBL leakage current thus further degrading transistor 

mobility. Furthermore, it is extremely difficult to control 4~5nm 

SOI channel thickness uniformly and reliably across 12 inch 

wafers in the manufacturing line. How thin SOI channel 

thickness is required for 14nm FD-SOI technology? 3nm! It 

appears that FD-SOI is not scalerble. 

 





AKH0
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Re: 28nm FD-SOI
AKH0   7/21/2014 4:51:07 PM
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Dear Sang Kim

At Vg=0, the channel is fully depleted, whether it is in a planar FDSOI or in a FinFET with reasonably low doping. Even in a bulk planar device the top 10-20nm is depleted. That doesn't mean a well-behaved device is in punchthrough wheter it being FDSOI/FinFET/or bulk planar. Your way of describing what seems to be physics is incorrect. I would recommend you consult a text book. Punchthrough happens when gate significantly loses control of the channel and high current folows independent of the gate voltage. This is certainly not the case in all the I-Vs that have been published for sub-30nm gate length FDSOI devices. Drain-induced barrier lowerin (DIBL) is of course inherent to any short channel devices and you CANNOT make it zero. In fact I will argue it does not makes sense to make it smaller than about 100mV/V either.

 

Your assumption of the gate length needed for a given technology is also incorrect. Gate length has nothing to do with the technology node (and it didn't in the past). At 28nm, FDSOI is using a gate length of 24nm, which is shorter than any alternative at the same node. At 14nm, gate length will be most likely 20-22 nm and so is at 10nm. All needed from gate length is that it fits the required gate pitch and the numbers I quoted above fit the bill perfectly.

Finally, the rule of thumb requirements of the channel thickness for a given gate length are just guidlines. Many other parameters such as gate stack, junction design and BOX thickness affect the electrostatic of the device. This is also the case in FinFET. No one needs 3nm SOI for 14nm FDSOI.

 

 

 

 

 

michigan0
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Re: 28nm FD-SOI
michigan0   7/21/2014 8:29:49 PM
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Dear AKHO

 

Thanks for your comments 

 

Bulk planer device has shallow implant combined with retrograde 

deep implant to prevent punchthrough regard less Vg is on or off. 

What do you mean by top 10~20nm is depleted? Intel FinFETs 

also have PT implants. Here we are talking about un-doped 

FD-SOI.



AKH0
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Re: 28nm FD-SOI
AKH0   7/22/2014 12:07:43 AM
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In a bulk planar device with super steep retrograde well, gate only needs to control the top portion of the substrate. Current flow is blocked at deeper locations by the well doping. Similarly in the planar FDSOI gate only needs to control current flow in the SOI layer, below that current is blocked by the BOX. You can imagine an ideal super steep retrograde well device as being to be equal to an FDSOI device with a BOX thickness of zero. Would you say such a device will suffer from pinch through?

michigan0
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Re: 28nm FD-SOI
michigan0   7/23/2014 6:39:41 PM
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Sang Kim

 

28nm planar bulk that is in mass production today for several 

years has uniform doped substrate that provides a fixed Vt  

and fixed depletion depth determined by uniform substrate 

doping. In a bulk planar device with super steep retrograde 

well, Vt could be higher and variable, and the gate depletion  

is blocked by the well doping, not by current flow. The current 

doesn't flow in the well unless hot carrier effect. The current 

flows from source to drain. Furthermore, the drain electric

field will be significantly higher in the retrograde well. As a 

result, hot carrier induced device failure could be higher.

 

First, the planar FD-SOI is not manufactured at any technology

node yet. Why? The un-doped 28nm FD-SOI requires an ultra-thin SOI channel, for an example, a 7nm for 28nm FD-SOI. My 

question is how the ideal super steep retrograde process can

be implemented in the 7nm thin SOI channel? It appears that

the un-doped planar 28nm FD-SOI is stilll not manufacturable.




AKH0
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Re: 28nm FD-SOI
AKH0   7/23/2014 7:06:20 PM
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No, the doping is not uniform in bulk planar! The well is retrograde (although not ideal) and there are halos. The whole point is that the well and halo doping will take care of leakage at the depth and gate takes care of it at the surface. I agree with you that the ideal supersteep retrograde will end up with high drain leakage, but that's not the case in FDSOI because drain is isolated from the substrate by the BOX.

BTW, your point about Vt being higher and more variable in a retrograde well is not correct either. In fact it's the other way around! Please see page 230 of Taur and Ning's text book. With retrograde well design Vt is lower than a uniformly doped well and in the extreme case independent of the well doping. This is in fact what SuVolta is promoting. Of course, with Vt being independent of the well doping you cannot use Vt adjust anymore and need to rely on body bias. What FDSOI does is simply making an ideal retrograde well possible and allowing the well doping to have either n+ or p+ polarity for either NFET or PFET witout fearing about drain leakage.

 

 

 

 

 

 

michigan0
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Re: 28nm FD-SOI
michigan0   7/26/2014 12:37:42 AM
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Sang Kim

 

The 28nm planar bulk has retrograde and halos as you pointed 

out, but ends at the 28nm node. FDSOI is worse because 

FDSOI is not manufactured at any technology node yet as I

pointed out in my original post. Intel, IBM, TSMC and others 

attempted to extend the planar bulk to the 22nm node, but 

were not successful because of the short channel effect or 

unable to suppress transistor leakage current. Intel finally 

developed its first FDFinFETs at 22nm, and its 14nm FinFETs

are in high volume manufactured today. FinFET technology  

can be extended to the end of roadmap.



AKH0
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Re: 28nm FD-SOI
AKH0   7/26/2014 1:25:48 AM
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IBM's 22nm which is used for power8 is PDSOI, which is very similar to bulk planar in terms of scaling and in fact uses a gate length shorter than Intel's 22nm FinFET. Samsung and others made 20nm bulk planar and showed their results. ISDA's 20nm was shown in at VLSI 2012. TSMC is said to ship 20nm parts this year. The problem with 20nm was not scalability, it was cost. For your information foundry's 20nm uses 64nm metal pitch vs Intel's 80nm. Which means foundry is offering a denser technology, which of course comes at the cost of double patterning. FDSOI products have already made by ST, see for example NovaThor demo in early 2013 that clearly showed SOC benefit. Samsung is now committed to offer 28FDSOI to the public. I do not understand your repeated comment about 28nm bulk planar being in high volume for several years as a drawback of FDSOI. Yes, 28nm has been in production for several years, but it didn't come with all bells and whistles at the beginning. The first products used poly SiON gate stack and no strain element to keep cost down. Overtime several versions of the technology with different cost-performance trade offs were offered. They are put into volume manufacturing when fabless companies demand a certain performance and are willing to pay for that extra cost. 28FDSOI is no exception to this. Volume manufacturing was put on hold because customers did not demand. BTW, Intel's 14nm FinFET is not in manufacturing yet and there has been multiple delays. And there is no such thing as "end of roadmap". Technology is scaled as long as it makes financially sense to do so. Whether it's being conventional scaling of the transistor, being stacking in 3D, or a completely new technology the same way BJT was replaced by MOSFET logic.



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