Imperfection-immune VLSI logic circuits using Carbon Nanotube Field Effect Transistors

Carbon nanotube field-effect transistors (CNFETs) show big promise as extensions to silicon-CMOS because: 1) Ideal CNFETs can provide significant energy and performance benefits over silicon-CMOS, and 2) CNFET processing is compatible with existing silicon-CMOS processing. However, future gigascale systems cannot rely solely on existing chemical synthesis for guaranteed ideal devices. VLSI-scale logic circuits using CNFETs must overcome major challenges posed by: 1) Misaligned and mis-positioned Carbon Nanotubes (CNTs); 2) Metallic CNTs; and, 3) CNT density variations. This paper performs detailed analysis of the impact of these challenges on CNFET circuit performance. A combination of design and processing techniques, presented this paper, can enable VLSI-scale CNFET logic circuits that are immune to high rates of inherent imperfections. These techniques are inexpensive compared to traditional defect- and fault-tolerance, do not impose major changes in VLSI design flows, and are compatible with VLSI processing because they do not require special customization on chip-by-chip basis.