Kohlenstoff: Die Zukunft der Nanoelektronik?

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1 Kohlenstoff: Die Zukunft der Nanoelektronik? Prof. Udo Schwalke Institut für Halbleitertechnik & Nanoelektronik, TU Darmstadt IHTN Shigeo Maruyama, University of Tokyo, Japan

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

Transistors Carbon Nanotube Sensors Carbon Nanotube Non-Volatile Memory 2-D: Graphene &

3 Introduction: Motivation for Novel Materials & Devices The END of simple geometric downscaling! 35 Years of Happy Scaling Gilbert Declerck VLSI Symp Materials based scaling Silicides High-k (HfO 2, Gd 2 O 3, Pr 2 O 3 ) Metal Gates Strained Silicon Germanium??? Carbon?! G.E. Moore, No exponential is forever, ISSCC, 2003 Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 3

2005 Materials based scaling Silicides High-k (HfO 2, Gd 2 O 3, Pr 2 O 3 ) Metal Gates Strained

4 Carbon Nanotubes (CNTs) Electronic Properties MWNTs: Multi-walled nanotubes Always metallic 1991: Sumio Iijima Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 4

5 Carbon Nanotubes (CNTs) Electronic Properties SWNTs: Single rolled layers of graphene Metallic or semiconducting depending on their chirality r C h r = na r + m 1 a 2 m n 3j (semiconducting) Semiconducting SWNTs: High carrier mobility (> 50x) Eg 1/ d 1nm): Diameter need to be well controlled Large surface to volume ratio: Ideal for sensor applications Shigeo Maruyama, University of Tokyo, Japan IBM, 1998 Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 5

(> 50x) Eg 1/ d (1eV @ 1nm): Diameter need to be well controlled Large surface to volume ratio: Ideal for sensor

6 The Nano-Technology Gap: From Individual Devices to Mass-Fabrication??? From hand made CNT devices to CNT nanoelectronics technology?? Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 6

7 Institute for Semiconductor Technology & Nanoelectronics (ISTN)

8 ISTN Clean Room Facility: Search for Alternative Methods Silicon-Wafer Si-CMOS compatible large-scale CNT- device fabrication??? Anneal / CVD Ion-Implantation CMP E-Beam & Optical Lithography Electrical Testing RTA / RTO Metal PVD RIE/ Plasma Etching Bonded Chip Completed Circuit Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 8

?? Anneal / CVD Ion-Implantation CMP E-Beam & Optical Lithography Electrical Testing RTA

9 Novel Fabrication Method: 1. In-Situ CNT Growth Vd CH N 2 4 (900 C) Drain Source Gate Vg Dr. Shigeo MARUYAMA Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 9

10 Novel Fabrication Method: 2. Diameter Control of SWNTs CNT- Characterization: Atomic Force Microscopy (AFM) SiO2 SiO2 Test-Structure Diameter control via Ni nano-cluster size Nano-cluster size-control via metal catalyst layer thickness Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 10

(AFM) SiO2 SiO2 Test-Structure Diameter control via Ni nano-cluster size

11 Novel Fabrication Method: 3. Nano-scale Electrical Measurements (C-AFM) AFM Conductive Tip R = R c1, MΩ B * L CNT CNT Si Oxide R c1,2 60 kω B M 20 kω/µm AFM Chuck B S 60 MΩ/µm CNT- Electrode CNT Tip-CNT Local C-AFM measurement in one spot I-V characteristics of individual CNTs Semiconducting-SWNTs in the off-state Similar to results from Bachtold et al., Physical Review Letters, 84, 6082 (2000) Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 11

kω B M 20 kω/µm AFM Chuck B S 60 MΩ/µm CNT- Electrode CNT Tip-CNT Local C-AFM measurement in one spot I-V

12 Electrical Characterization: CNTFET Device Properties (1 s-swnt) ABS (Ids) (A) On-current: 400 na Vds Drain Ids Pd AlxOy SiO 2 Gate Vgs Vds = 400 mv 180 mv/dec Pd Source On/off ratio: Off-current: 0.2 pa Vgs (V) - unipolar - PMOS-like FET - on-current: 400 na 400 Vd=-0.4V L = 3 µm - on/off ratio: > 10 6 L. Rispal, T. Tschischke, H. Yang, U. Schwalke, Jap. Journal of Applied Physics, Vol. 47, No. 4B, pp (2008) Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 12

2 pa -3-2 -1 0 1 2 3 Vgs (V) - unipolar - PMOS-like FET - on-current: 400 na 400 µa/µm @ Vd=-0.4V L = 3 µm - on/off ratio: > 10 6 L. Rispal, T.

13 Mass-Fabrication: CNTFET Devices 102 CNTFETs Gate length from 1,6 µm to 6 µm Non-optimized layout: ~ 1000 CNTFETs per wafer At present 15 wafers processed, equivalent to transistors. Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 13

present 15 wafers processed, equivalent to 15 000 transistors.

14 Sensor Applications: CNTFETransistor CNTFESensor Jing Kong, Nathan R. Franklin, Chongwu Zhou, Michael G. Chapline, Shu Peng, Kyeongjae Cho, Hongjie Dai SCIENCE VOL 287 (2000) Vt-shift: Change in the charging state Active sensor: Intrinsic amplification Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 14

Chapline, Shu Peng, Kyeongjae Cho, Hongjie Dai SCIENCE VOL 287 (2000) Vt-shift:

15 Sensor Applications: CNTFES Bio-Sensor Detection of bio-molecular particles (proteins, viruses ) Selectivity via functionalization e.g. lipid bi-layer with viral receptor e.g. H1N1 Bonding of the virus: change in the charging state shift in the electrical characteristics High detection sensitivity Single molecule level CNTFET CNTFES Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 15

16 Towards Commercial Sensor Applications: Hybrid CNT-CMOS Smart Sensors Systems Implantable Sensor System/ Lab-on-a-Chip Excellent sensitvity Ultra-low power Ultra small CMOS compatible U. Schwalke, L. Rispal, Fabrication of Ultra-Sensitive Carbon Nanotube Field-Effect Sensors (CNTFES) for Biomedical Applications, 213th ECS, Phoenix, USA (2008) Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 16

Rispal, Fabrication of Ultra-Sensitive Carbon Nanotube Field-Effect Sensors (CNTFES) for Biomedical

17 From CNT-Logic & Sensors to CNT-Memory: Charge-Trapping FET Memories M. S. Fuhrer et al., Nano Lett., 755, Vol. 2, No. 7, 2002 J. B. Cui et al. Appl. Phys. Lett., 3260, Vol. 81, No. 17, 2002 M. Radosavljevic et al., Nano Lett., 761, Vol. 2, No. 7, 2002 C. H. Lee et al., Jpn. J. Appl. Phys., 5392, Vol. 42 (2003) S. Wang et al. APPLIED PHYSICS LETTERS 87, M. Y. Zavodchikova et al., phys. stat. sol. (b) 244, No. 11, (2007) On/off ratios: 100 to 1000 Logic 1 / 0 : 100 Data retention: > 12 days Endurance: > 100 cycles Wang et al. Only few individual memory devices Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 17

APPLIED PHYSICS LETTERS 87, 133117 2005 M. Y. Zavodchikova et al., phys. stat. sol. (b) 244, No.

18 Basic Memory Functionality: Voltage Programmable Hysteresis Ids (A) logical "1" memory window logical "0" read voltage Vgs (s) Hysteresis: Charge trapping in the Al x O y or at the Al x O y / SiO 2 interface Performance: Ion / I off ratio: ~10 7 S 1 / 0 ratio: ~10 6 G D Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 18

Hysteresis: Charge trapping in the Al x O y or at the Al x O y / SiO 2 interface Performance: Ion / I off

19 Basic Memory Functionality: Data Retention Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 19

20 Basic Memory Functionality: Endurance Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 20

21 Mass-Fabrication: Yield Statistics Functional Yield Device Yield Total devices: 252 ~ 48% Total Yield Total devices: 180 Oxide thickness: 38 nm Gate length: 2 to 6 µm Rispal, Schwalke, IEEE Electron Device Letters Vol. 29 (12), 1349 (2008) Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 21

22 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 Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 22

Z. Sowjet. 11 (1937) 26 Mermin, PRL 17 (1966) 1133, Phys. Rev 176 (1968) 250.) Science, Oct.

23 Graphene for Nanoelectronic Devices Graphene 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) , Landau, Phys. Z. Sowjet. 11 (1937) 26 Mermin, PRL 17 (1966) 1133, Phys. Rev 176 (1968) 250.) Science, Oct zigzag edge armchair edge Geim,Novoselov, Nature Materials 6, 183 (2007) Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 23

24 Favored Industrial Approach: Graphene Devices Top-Down Metal Gate High-k 1mm Micro-Electronics Source Au Graphene 1µm Top-down SiO 2 Silicon Nano-Electronics 1nm Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 24

25 Graphene Fabrication: Exfoliation Technique Highly Oriented Pyrolytic Graphite Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 25

26 Graphene Fabrication: Exfoliation - Way to Mass-Fabrication? (high magnification) Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 26

27 Novel Approach to Graphene Fabrication: Catalytic CVD Growth of Graphene AFM Tip Catalyst Graphene Oxide Si-Wafer Si AFM Optical Microscope U. Schwalke, IEEE SCS 2009, Djerba CH 4 + H2 CVD Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 27

28 Conclusion Kohlenstoff: Die Zukunft der Nanoelektronik!! carbon!!! High Performance Silicon Chips Powered by Carbon-Nanotubes & Graphene Inno.CNT 2010 Kohlenstoff: Die Zukunft der Nanoelektronik? Udo Schwalke 28

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