kohlenstoff: die zukunft der nanoelektronik? ihtn...kohlenstoff: die zukunft der nanoelektronik?...

Kohlenstoff: Die Zukunft der Nanoelektronik?

Prof. Udo SchwalkeInstitut für Halbleitertechnik & Nanoelektronik, TU Darmstadt

IHTN

Shigeo Maruyama, University of Tokyo, Japan

Inno.CNT 2010 | Kohlenstoff: Die Zukunft der Nanoelektronik? | Udo Schwalke | 2

Outline

Introduction: Motivation for Novel Materials & Devices

Carbon Nanotubes (CNTs): Electronic Properties

1-D: Carbon Nanotube Devices Carbon Nanotube Field-Effect Transistors Carbon Nanotube Sensors Carbon Nanotube Non-Volatile Memory

2-D: Graphene & Graphene Devices

Conclusion


Introduction:Motivation for Novel Materials & Devices

G.E. Moore, No exponential is forever…, ISSCC, 2003

35 Years of „Happy Scaling“Gilbert DeclerckVLSI Symp. 2005 Materials

based scaling

•Silicides•High-k (HfO2, Gd2O3, Pr2O3…)•Metal Gates•Strained Silicon•Germanium•???…•… Carbon?!

The END of simple geometric down-scaling!


MWNTs: Multi-walled nanotubes Always metallic

1991: Sumio Iijima

Carbon Nanotubes (CNTs)Electronic Properties


SWNTs: Single rolled layers of graphene

Metallic or semiconductingdepending on their chirality

Semiconducting SWNTs: High carrier mobility (> 50x) Eg ≈ 1/ d (1eV @ 1nm):

Diameter need to be well controlled

Large surface to volume ratio: Ideal for sensor applications

Shigeo Maruyama, University of Tokyo, Japan

IBM, 1998

21 amanCh

rrr+=

m – n ≠ 3j (semiconducting)

Carbon Nanotubes (CNTs)Electronic Properties


The Nano-Technology Gap: From Individual Devices to Mass-Fabrication

From „hand made“ CNT devices to

CNT nanoelectronics technology ??

??????

Institute for Semiconductor Technology & Nanoelectronics (ISTN)

www.iht.tu-darmstadt.de


Anneal / CVD Ion-Implantation

RTA / RTO

Metal PVD Completed Circuit

Electrical Testing

RIE/ Plasma Etching

CMP

Silicon-Wafer

E-Beam & OpticalLithography

Bonded Chip

SiSi--CMOS compatible CMOS compatible largelarge --scale CNTscale CNT --

device device fabrication???fabrication???

ISTN Clean Room Facility:Search for Alternative Methods


N2 (900°C)CH4 (900°C)

Vg

Vd

Gate

Drain Source

Novel Fabrication Method:1. In-Situ CNT Growth

Dr. Shigeo MARUYAMA


SiO2

SiO2

Test-Structure

Novel Fabrication Method:2. Diameter Control of SWNTs

CNT- Characterization: Atomic Force Microscopy (AFM)

•Diameter control viaNi nano-cluster size

•Nano-cluster size-control via metal catalyst layer thickness


Novel Fabrication Method:3. Nano-scale Electrical Measurements (C-AFM)

Rc1,2 ≈ 60 kΩ

BM ≈ 20 kΩ/µm

BS ≈ 60 MΩ/µm

R = Rc1,2 + B * LCNT

Si

AFM Chuck

AFM Conductive Tip

CNT

Tip-CNTCNTCNT-Electrode

Oxide

Si

AFM Chuck

AFM Conductive Tip

CNT

Tip-CNTCNTCNT-Electrode

Oxide

• Local C-AFM measurement in one spot

• I-V characteristics of individualCNTs

≈ 80 - 150MΩ

• Semiconducting-SWNTs in the off-state

•Similar to results from Bachtoldet al., Physical Review Letters , 84, 6082 (2000)


Electrical Characterization: CNTFET Device Properties (1 s-SWNT)

- unipolar

- PMOS-like FET

- on-current: 400 nA→ 400 µA/µm

@ Vd=-0.4VL = 3 µm

- on/off ratio: > 106

SiO2

AlxOyPdPd

Vgs

Vds

Gate

Drain Source

IdsSiO2

AlxOyPdPd

SiO2SiO2

AlxOyPdPd

Vgs

Vds

Gate

Drain Source

Ids

L. Rispal, T. Tschischke, H. Yang, U. Schwalke, Jap. Journal of Applied Physics, Vol. 47, No. 4B, pp. 3287 –

3291 (2008)

-3 -2 -1 0 1 2 310-14

10-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

Off-current: 0.2 pA

On-current: 400 nA

180 mV/Dec

Vds = 400 mV

AB

S (

Ids)

(A

)

Vgs (V)

On/off ratio:

2 × 106


Mass-Fabrication:CNTFET Devices

102 CNTFETsGate length from1,6 µm to 6 µm

At present 15 wafers processed, At present 15 wafers processed, equivalent to 15 000 transistors.equivalent to 15 000 transistors.

Non-optimized layout: ~ 1000 CNTFETs per wafer


Jing Kong, Nathan R. Franklin, ChongwuZhou, Michael G. Chapline, Shu Peng, Kyeongjae Cho, Hongjie Dai

SCIENCE VOL 287 (2000)

Vt-shift: Change in the charging state

Active sensor: Intrinsic amplification

Sensor Applications: CNTFETransistor CNTFESensor


Detection of bio-molecular particles (proteins, vir uses…)Selectivity via functionalization e.g. lipid bi-laye r with viral receptor

Bonding of the virus: change in the charging stateshift in the electrical

characteristicsHigh detection sensitivity Single molecule level

CNTFET CNTFES

e.g. H1N1

Sensor Applications: CNTFES Bio-Sensor


Implantable Sensor System/ Lab-on-a-Chip

Towards Commercial Sensor Applications: Hybrid CNT-CMOS Smart Sensors Systems

• Excellent sensitvity• Ultra-low power • Ultra small• CMOS compatible CMOS compatible

U. Schwalke, L. Rispal, “Fabrication of Ultra-Sensitive Carbon Nanotube Field-Effect Sensors (CNTFES) for Biomedical Applications“, 213th ECS, Phoenix, USA (2008)


M. S. Fuhrer et al., Nano Lett., 755, Vol. 2, No. 7, 2002 J. B. Cui et al. Appl. Phys. Lett., 3260, Vol. 81, N o. 17, 2002M. Radosavljevic et al., Nano Lett., 761, Vol. 2, No. 7, 2002 C. H. Lee et al., Jpn. J. Appl. Phys., 5392, Vol. 4 2 (2003)S. Wang et al. APPLIED PHYSICS LETTERS 87, 133117 2 005M. Y. Zavodchikova et al., phys. stat. sol. (b) 244, No. 11, 4188–4192 (2007)

Wang et al.

•On/off ratios: 100 to 1000

•Logic „1“/“0“: ≤ 100

•Data retention: > 12 days

•Endurance: > 100 cycles

Only few individual memory devices

From CNT-Logic & Sensors to CNT-Memory:Charge-Trapping FET Memories


Basic Memory Functionality: Voltage Programmable Hysteresis

-5 -4 -3 -2 -1 0 1 2 3 4 510-1510-1410-1310-1210-1110-1010-910-810-710-610-5

logical "0"

Ids

(A)

Vgs (s)

logical "1"

memory window

read voltage

Hysteresis: • Charge trapping in

the AlxOy

• or at the AlxOy / SiO2

interface

Performance: • Ion / I off ratio: ~107

• 1 / 0 ratio: ~106

G

S D


Basic Memory Functionality: Data Retention


Basic Memory Functionality: Endurance


Mass-Fabrication: Yield Statistics

Total devices: 252

Oxide thickness: 38 nmGate length: 2 to 6 µm

Total devices: 180

~ 48% Total Yield

Functional Yield Device Yield

Rispal, Schwalke, IEEE Electron Device LettersVol. 29 (12), 1349 (2008)


Outline

Introduction: Motivation for Novel Materials & Devices

Carbon Nanotubes (CNTs): Electronic Properties

1-D: Carbon Nanotube Devices Carbon Nanotube Field-Effect Transistors Carbon Nanotube Sensors Carbon Nanotube Non-Volatile Memory

2-D: Graphene & Graphene Devices

Conclusion


Graphene for Nanoelectronic DevicesGraphene in a “free” state?

Strictly 2D crystal should not exist: (Peierls, Helv. Phys. Acta 7 (1934) 81-83,Peierls, Ann. Inst. H. Poincare 5 (1935) 177-222,Landau, Phys. Z. Sowjet. 11 (1937) 26Mermin, PRL 17 (1966) 1133, Phys. Rev 176 (1968) 250.)

Science, Oct. 2004

armchair edge

zigzag edge

armchair edge

zigzag edge

Geim,Novoselov, Nature Materials 6, 183 (2007)


Favored Industrial Approach:Graphene Devices Top-Down

1µm

1mm

1950 1990 2030

Micro-Electronics

TopTopTopTop----dow

ndow

ndow

ndow

n

Nano-Electronics

1nm

Silicon

Silicon

Silicon

Silicon

SiOSiOSiOSiO2222

AuAuAuAu Graphene

Graphene

Graphene

Graphene

HighHighHighHigh----kkkk

Metal Metal Metal Metal

GateGateGateGate

SourceSourceSourceSource


Graphene Fabrication:Exfoliation Technique

Highly OrientedPyrolytic Graphite


Graphene Fabrication:Exfoliation - Way to Mass-Fabrication?

(high magnification)


Si

AFM Tip

Graphene

Si-Wafer

Catalyst

Oxide

Optical Microscope

CH4 + H2 CVD

Novel Approach to Graphene Fabrication:Catalytic CVD Growth of Graphene

AFM

U. Schwalke, IEEE SCS 2009, Djerba


Conclusion

High Performance Silicon Chips Powered by Carbon-Nanotubes & Graphene

!!!!!!

carbon

carbon

carbon

carbon

carbon

carbon

carbon

carbon

Kohlenstoff: Die Zukunft der Kohlenstoff: Die Zukunft der NanoelektronikNanoelektronik !!!!

kohlenstoff: die zukunft der nanoelektronik? ihtn...kohlenstoff: die zukunft der nanoelektronik?...

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