easiest monolithic 3d ic

MonolithIC 3D Inc. Patents Pending 1

Monolithic 3D – The Most Effective Path for

Future IC Scaling

Agenda:

Semiconductor Industry is reaching an inflection point

Monolithic 3D IC – The next generation technology driver Monolithic 3D – Game Change, using existing transistor

process ! Heat removal The MonolithIC 3D Advantages Summary

Martin van den Brink -EVP & CTO, ASMLISSCC 2013 & SemiconWest 2013

The Current 2D-IC is Facing Escalating Challenges

On-chip interconnect is Dominating device power consumption, performance and cost

B. Wu, A. Kumar, Applied Materials

3D and EDA need to make up for Moore’s Law, says Qualcomm*

“Qualcomm is looking to monolithic 3D and smart circuit architectures to make up for the loss of traditional 2D process scaling as wafer costs for advanced nodes continue to increase. .. Now, although we are still scaling down it’s not cost-economic anymore”

“Interconnect RC is inching up as we go to deeper technology. That is a major problem because designs are becoming interconnect-dominated. Something has to be done about interconnect. What needs to be done is monolithic three-dimensional ICs.”

“TSV...are not really solving the interconnect issue I’m talking about.So we are looking at true monolithic 3D. You have normal vias between different stacks.”

* Karim Arabi Qualcomm VP of engineering, DAC 2014

Key Note <http://www.techdesignforums.com/blog/2014/06/05/karim-arabi-monolithic-

3dic-dac-2014/>

Monolithic 3D Qualcomm SoCs by 2016**EE Times 3/31/2015 <http://www.eetimes.com/document.asp?doc_id=1326174&piddl_msgid=338050#msg_338050>

“3DV, enables die size to be shrunk in half, while simultaneously increasing yields,“

Qualcomm's motivation, according to Arabi, is market share in the 8 billion smartphones that he predicts will be produced from 2014 to 2018

6

In the fabrication process of front-to-back (F2B) 3DVs (a) the bottom tier is created the same way as 2D-ICs. (b,c,d) To add another layer, first a thin layer of silicon is deposited on top of the bottom tier. (e) This front-end-of-line (FEOL) process of the top tier permits the addition of normal vertical vias and top-tier contacts. (f) Finally back-end-of-line (BEOL) processing creates the top-tier. (Source:Qualcomm)

http://www.eetimes.com/document.asp?print=yes&doc_id=1326174&image_number=2

Even Intel Agrees – 7nm is the Limit for SiliconISSCC 2015

“Bohr predicted that Moore's Law will not come to an abrupt halt, but will morph and evolve and go in a different direction, such as scaling density by the 3D stacking of components rather than continuing to reduce transistor size.”*http://www.v3.co.uk/v3-uk/news/2403113/intel-predicts-moores-law-to-last-another-10-years

”Intel’s Bohr agrees that 3D structures will become more important. He said the kind of through-silicon vias used for today’s chip stacks need to improve in their density by orders of magnitude.”**http://www.eetimes.com/document.asp?doc_id=1326336&page_number=5

“Samsung spent several years developing its 14nm technology and debating which process node it would invest in after 28nm. Low expects that 28nm will still be a popular process node for years to come because of its price…The cost per transistor has increased in 14nm FinFETs and will continue to do so, Low said, so an alternative technology such as 28nm SOI is necessary.”**http://www.eetimes.com/document.asp?doc_id=1326369

http://www.eetimes.com/document.asp?doc_id=1326369

http://www.eetimes.com/document.asp?doc_id=1326369

Conclusions:

Dimensional Scaling (“Moore’s Law”) is already exhibiting diminishing returns

The path beyond 2017 (7nm) is unclear While the research community is working on many interesting

new technologies (see below), none of them seem mature enough to replace silicon for 2019

- Carbon nanotube - Indium gallium arsenide - 2D (MoS2, etc.) transistors- Graphene - Spintronics - Nanowire - Molecular computing- Photonics - Quantum computing

3D IC is considered, by all, as the near-term solution, Monolithic 3D IC is well positioned to be so, as it uses the existing infrastructure! It is safe to state that Monolithic 3D is the only alternative

that could be ready for high volume in 2019 !!

11

MONOLITHIC 10,000x the Vertical Connectivity of TSV

12

Processing on top of copper interconnects should not make the copper interconnect exceed 400oC

How to bring mono-crystallized silicon on top at less than 400oC How to fabricate state-of-the-art transistors on top of copper interconnect and keep

the interconnect below at less than 400oC

Misalignment of pre-processed wafer to wafer bonding step used to be ~1µm

How to achieve 100nm or better connection pitch How to fabricate thin enough layer for inter-layer vias of ~50nm

The Monolithic 3D ChallengeWhy is it not already in wide use?

MonolithIC 3D – Innovative Flows

RCAT (2009) – Process the high temperature on generic structures prior to ‘smart-cut’, and finish with cold processes – Etch & Depositions

Gate Replacement (2010) (=Gate Last, HKMG) - Process the high temperature on repeating structures prior to ‘smart-cut’, and finish with ‘gate replacement’, cold processes – Etch & Depositions

Laser Annealing (2012) – Use short laser pulse to locally heat and anneal the top layer while protecting the interconnection layers below from the top heat

Game Change, using existing transistor process ! Modified ELTRAN (2015) – Use ELTRAN for low

cost, No defects, Existing transistor flow Precise Bonder (2014) – Use new precise bonders,

offering low cost flow with minimal R&D

ELTRAN® - Epitaxial Layer TRANsferOriginated, developed and produced at Canon Inc.


ELTRAN® - Epitaxial Layer TRANsfer

M3D Leveraging the ELTRAN IdeaBoth donor and carrier wafer could be pre-

processedDonor wafer:

Carrier wafer:

No impact on processed layer or on device processing

Donor and Carrier could be easily recycled – reused

Minimal incremental cost per layer (porous + epi <$20)

porous ‘cut’ layerepi. layer

Base wafer - reused

porous ‘cut’ layeroxide layer

Base wafer - reused

17

~700 µm Donor Wafer

Use standard flow to process “Stratum 3”- using ELTRAN donor wafer (through silicidation)

MonolithIC 3D Inc. Patents Pending

Stratum 3

porous layer

PMOSNMOS

Silicon

PolyOxide

STI

epi

18

~700µm Donor Wafer

Silicon

Bond to a ELTRAN carrier-wafer

~700µm Carrier Wafer

STI

oxide to oxide bond

porous layer

19

~700µm Donor Wafer

‘Cut’ Donor Wafer off


Transferred ~100nm Layer- Stratum 3

Silicon

Silicon

STI

20

Etch Off the Porous Silicon and Smooth


~100nm STI

Silicon

Oxide

porous layer

21

Use standard flow to process “Stratum 2”Note: High Temperature is OK

~100nm Layer


Silicon

Porous ‘cut’ layer

STI

High Performance Transistors Oxide

Stratum 2

Stratum 3

Need to set vertical isolation

22

Add at least one interconnect layer


~100nmTransferred Layer

Stratum-2 copper interconnection layers

Stratum 2

Stratum 3

For some applications such asImage Sensor, this could be it !


Transfer onto Final carrier


Oxide-oxide bond

TransferredLayer (Stratum 2

+Stratum 3)

Final Carrier

porous ‘cut layer


Remove carrier-wafer

Oxide-oxide bond


+Stratum 3)

Final Carrier


Add Stratum-3 Interconnections

Oxide-oxide bond


+Stratum 3)

Final Carrier

Precise Bonder – Multi-Strata M3D

Utilizing the existing front-end process !!!<200 nm (3σ)

Achieving 10,000x vertical connectivity as the upper strata will be thinner than 100 nmMix – Sequential/Parallel M3DLow manufacturing costs


Transfer onto Pre-Processed Wafer


Oxide-oxide bond


+Stratum 3)

Base WaferPMOSNMOS


Remove Carrier Wafer

Oxide-oxide bond


+Stratum 3)

Base WaferPMOSNMOS


Connect to Stratum 1

Oxide-oxide bond


+Stratum 3)

Base WaferPMOSNMOS


Add Metal Layers

Oxide-oxide bond


+Stratum 3)

Base WaferPMOSNMOS

Monolithic 3D using ELTRAN & Precise Bonder

Utilizes existing transistor processCould help upgrade any fab (leading or

trailing)Very competitive cost structureBetter power, performance, price than a

node of scaling at a fraction of the costs !!! Allows functionality that could not be

attained by 2D devices

The Operational Thermal Challenge

Upper tier transistors are fully surrounded by oxide and have no thermal path to remove operational heat

Good Heat Conduction~100 W/mK

Poor Heat Conduction~1 W/mK

The Solution

Use Power Delivery (Vdd, Vss) Network (“PDN”) also for heat removal

Add heat spreader to smooth out hot spotsAdd thermally conducting yet electrically

non-conducting contacts to problem areas such as transmission gates

Cooling Three-Dimensional Integrated Circuits using

Power Delivery Networks (PDNs)

Hai Wei, Tony Wu, Deepak Sekar*, Brian Cronquist*, Roger Fabian Pease, Subhasish Mitra

Stanford University, Monolithic 3D Inc.*

35

IEDM 2012 Paper

Monolithic 3D Heat Removal Architecture (Achievable with Monolithic 3D

vertical interconnect density)

Global power grid shared among multiple device layers, local power grid for each device layer

Local VDD grid architecture shown above

Optimize all cells in library to have low thermal resistance to VDD/VSS lines (local heat sink)

px

py

Patented and Patent Pending Technology

2060

100140

0 10 20 30 40Tem

pera

ture

(ºC

)

× 100 TSVs /mm2

Monolithic 3D IC

Without Power Grid

With Power Grid

Signal wire

Heat sink

1. Reduction die size and power – doubling transistor count - Extending Moore’s law

Monolithic 3D is far more than just an alternative to 0.7x scaling !!!2. Significant advantages from using the same fab, design tools3. Heterogeneous Integration4. Multiple layers Processed Simultaneously - Huge cost reduction (Nx) 5. Logic redundancy => 100x integration made possible6. 3D FPGA prototype, 2D volume7. Enables Modular Design8. Naturally upper layers are SOI9. Local Interconnect above and below transistor layer10.Re-Buffering global interconnect by upper strata11.Others

A. Image sensor with pixel electronics B. Micro-display

The Monolithic 3D Advantage

Reduction of Die Size & Power – Doubling Transistor Count Extending Moore’s law

Reduction of Die Size & PowerIntSim v2.0 free open source >600

downloads

Repeater count increases exponentially with scaling At 45nm, repeaters >50% of total leakage power of chip [IBM]. Future chip power, area could be dominated by interconnect

repeaters [Saxena P., et al. (Intel), TCAD, 2004]

Only Monolithic 3D (TSV size ~0.1 µm) would Provide an Alternative to Dimensional Scaling

*IEEE IITC11 Kim

IV. Heterogeneous Integration

Logic, Memories, I/O on different strata Optimized process and transistors for the function Optimizes the number of metal layers Optimizes the litho. (spacers, older node)

Low power, high speed (sequential, combinatorial)

Different crystals – E/O

V. Multiple Layers Processed Simultaneously - Huge Cost Reduction (Nx) –”BICS”

Multiple thin layers can be process simultaneously, forming transistors on multiple layers

Cost reduction correlates with number of layers being simultaneously processed (2, 4, 8, 16, 32, 64, 128, ...)

3D DRAM 3.3x Cost Advantage vs. 2D DRAM

Conventional stacked capacitor DRAM

Monolithic 3D DRAM with 4 memory layers

Cell size 6F2 Since non self-aligned, 7.2F2

Density x 3.3x

Number of litho steps 26 (with 3 stacked cap. masks)

~26 extra masks for memory layers, but no

stacked cap. masks)


VI. Logic Redundancy => 100x Integration Made Possible

It is well known the more we can integrate on one chip with reasonable yield, the better the cost & performance – Moore’s Law

Yield is the dominating criterion when to use PCB rather than on-chip integration

Innovation Enabling ‘Wafer Scale Integration’ – 99.99% Yield with 3D Redundancy

Swap at logic cone granularity Negligible design and power penalty Redundant 1 above, no performance penalty

Gene Amdahl -“Wafer scale integration will only work with 99.99% yield, which won’t happen for 100 years” (Source: Wikipedia)

Server-Farm in a BoxWatson in a Smart Phone…


FPGA Achilles’ Heel – PIC (Programmable Interconnect) >30x Area vs. Antifuse/Masked Via

Average area ratio of connectivity element >30

Current FPGAs use primarily pass

transistors with a driver.

ViaPitch - 0.2

.2 x .2= 0.04 2

Area: 0.04 2

SRAM FPGA connectivity

elements @ 45 nm

Via connectivity element @ 45 nm

.2

SRAMbit

SRAMbit

SRAMbit

SRAMbit

Bidi buffer Area 4 2

Ratio to AF 100

TS buffer Area 2 2

Ratio to AF 50

Pass gate Area .5 2

Ratio to AF 12

4X

10X

4X

4X

.2

Via/AF

The Twin - Field-programmable & via-configurable fabric

Prototype Phase Production Phase

• Prototype volumes• Prototype costs• Std. logic w/mono-3D• OTP till design &

functions stabilized• Specific foundry

• Production volumes• Production costs• Standard logic process• 1-Mask customization• Backup-foundry capable

Anti-fuses

HV Programming TransistorsVp

VII. Enables Modular Design

Platform-based design could evolve to: Few layers of generic functions like compute, radios, and

one layer of custom design Few layers of logic and memories and one layer of FPGA ...

VIII. Naturally Upper Layers are SOI

SOI wafers provides many benefits with one major drawback: cost of the blank wafer.

In monolithic 3D – all the upper strata are naturally SOI

IX. Local Interconnect - Above and Below Transistor Layer

Increased complexity requires increased connectivity. Adding more metal layer increases the challenge of connecting upper layers to the transistor layer below.

Intel March, 2013

X. Re-Buffering Global Interconnect by Upper Strata

Global interconnect is done at the upper and thicker metal layers. It would increase efficiency if these layers could re-buffer instead of connecting to base layer using multiple vias and blocking multiple metal tracks.ÞUse the layers above for re-buffering.

XI. Others A. Image Sensor with Pixel Electronics

With rich vertical connectivity, every pixel of an image sensor could have its own pixel electronics underneath


XI. Others B. Micro-display

Use of three crystal layers to form RGB LED arrays with drive electronics underneath


Current Status

70 Fundamental Patents have been Granted 67 Fundamental Patents have already been issued

>100 Applications have been filedNuPGA-15 US 8,273,610 was issued Sept 25,2012 (880 pages !)


Monolithic 3D Provides an Attractive Path to…

3D-CMOS: Monolithic 3D Logic Technology

3D-FPGA: Monolithic 3D Programmable Logic

3D-GateArray: Monolithic 3D Gate Array

3D-Repair: Yield recovery for high-density chips

3D-DRAM: Monolithic 3D DRAM

3D-RRAM: Monolithic 3D RRAM

3D-Flash: Monolithic 3D Flash Memory

3D-Imagers: Monolithic 3D Image Sensor

3D-MicroDisplay: Monolithic 3D Display

3D-LED: Monolithic 3D LED

Monolithic 3D Integration with Ion-

Cut Technology

Can be applied to many market

segments

LOGIC

MEMORY

OPTO-ELECTRONICS


Summary

We have reached an inflection point Multiple practical paths to monolithic 3D existHeat removal of monolithic 3D could be

designed inBreaking News – The process barriers are

now removed

=> Monolithic 3D – The Most Effective Path for Future IC Scaling

Smart Alignment

200nm

200nm

Through Layer Via connected by landing pad of 200x200 nm²

Smart Alignment

61

‘Smart-Alignment’

Bottom layerlayout

Landing pad

Vertical connection1 for 200nmx200nm

Vertical connection200nm/metal pitch ~ 20for 200nmx200nm

~20X better vertical connectivity Minimum abstraction for routing

‘Smart-Alignment’

Patents Pending