TECHNIQUES OF SYNTHESIZING CARBON NANOTUBE FETS FOR INTEGRATED CIRCUITS GAO, Feng S.I.D

PART I. NANOTUBE PLACEMENT PART II. COMPLEMENTARY DEVICES PART III. IMPERFECTION REMEDY

2. Deposit NMPI (Self Aligned) 4. Ion exchange reaction 3. Aqueous CNT solutions preparation Self-Assembly Approach [1,2] NANOTUBE PLACEMENT [1] Park, Hongsik, et al. "High-density integration of carbon nanotubes via chemical self-assembly." Nature nanotechnology 7.12 (2012): [2] Wu, Justin, et al. "Top ‐ Down Patterning and Self ‐ Assembly for Regular Arrays of Semiconducting Single ‐ Walled Carbon Nanotubes." Advanced Materials (2014):

Dielectrophoresis [3] NANOTUBE PLACEMENT [3] Shekhar, Shashank, Paul Stokes, and Saiful I. Khondaker. "Ultrahigh density alignment of carbon nanotube arrays by dielectrophoresis." ACS nano 5.3 (2011): CNT density controlled by solution concentration ranges from 0.5 – 30 SWNT/ μ m 1. Pre-pattern electrodes 2. Oxygen plasma cleaning 3.DEP with DC 5 Vpp at 300kHz for 30s 4. Blown dry by N 2 gas

NANOTUBE PLACEMENT Transfer Approach (Langmuir–Schaefer Method) [4] Semiconductor CNT purity: 99% CNT density: 500 tubes/μm (full converage) [4] Cao, Qing, et al. "Arrays of single-walled carbon nanotubes with full surface coverage for high - performance electronics." Nature nanotechnology 8. 3 (2013):

Controlled Growth [5] NANOTUBE PLACEMENT [5] Papadopoulos, Chris, and Badr Omrane. "Nanometer ‐ scale Catalyst Patterning for Controlled Growth of Individual Single ‐ walled Carbon Nanotubes." Advanced Materials 20.7 (2008): Pattern catalyst 2. Grow CNT 3. Fabricate electrodes and gates

COMPLEMENTARY DEVICES 1. Contact Controlled Devices Type [6] High Work Function Metal (Pd, Au) Femi Level Near to Valence Band p-FET Low Work Function Metal (Sc, Y, Er) Femi Level Near to Conduction Band n-FET Problem: Low work function metals are readily oxidized Solution: Cover with inert metal and passivation layer [6] Han, S-J., et al. "Carbon nanotube complementary logic based on erbium contacts and self-assembled high purity solution tubes." IEEE Int. Electron Dev. Meet 19 (2013): 1-19.

COMPLEMENTARY DEVICES 2. Dielectric Controlled Device Type [7] 3. Chemical Doping for n-FET [8] n-FETp-FET [7] Franklin, Aaron D., et al. "Carbon nanotube complementary wrap-gate transistors." Nano letters 13.6 (2013): [8] Javey, Ali, et al. "High performance n-type carbon nanotube field-effect transistors with chemically doped contacts." Nano letters 5.2 (2005): Potassium (K) Doping, Introduce electron carriers

REMEDY FOR IMPERFECTION 1. Cleaning metallic CNTs [9] G D S G D S Apply high voltage Breakdown voltage of semiconductor CNT is larger than metallic CNT [9] Kim, Sunkook, et al. "Current on/off ratio enhancement through the electrical burning process in ambient with/without oxygen for the generation of high-performance aligned single- walled carbon nanotube field effect transistors." Applied Physics Letters (2010): m-CNTs-CNT

REMEDY FOR IMPERFECTION 2. Mis-positioned CNT Immune Design [10] [10] Zhang, Jie, et al. "Robust digital VLSI using carbon nanotubes." IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 31.4 (2012): Etched Regions Mis-positioned caused error After etch Mispositioned CNT-immune Layout for SOP form

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