Scaling down contact length in complementary carbon nanotube field-effect transistors

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Scaling down complementary field-effect transistors (FETs) is crucial for advancing integrated circuit technology.
• Carbon nanotube (CNT) based FETs offer potential advantages in terms of performance and power consumption.
• Efficient electrical contacts are essential for optimizing CNT FET performance, especially at smaller scales.

Purpose of the Study:

• To experimentally investigate the contact length (Lc) scaling behavior of scandium (Sc)-contacted and palladium (Pd)-contacted CNT complementary FETs.
• To determine the contact resistance of Sc/CNT and Pd/CNT contacts using the transfer length method (TLM).
• To assess the viability of Sc contacts for future scaled-down complementary CNT FET technology.

Main Methods:

• Fabrication and characterization of CNT complementary FETs with Sc (n-type) and Pd (p-type) contacts.
• Application of the transfer length method (TLM) to extract contact resistance from experimental data.
• Analysis of contact performance as a function of contact length (Lc), considering the effects of Sc film oxidation.

Main Results:

• Sc-contacted CNT FETs demonstrated Lc scaling performance comparable to Pd-contacted ones for Lc > 40 nm.
• Sc/CNT contact performance degraded significantly below 40 nm Lc due to surface oxidation of the Sc film.
• After correcting for oxide thickness, the intrinsic contact scaling of Sc/CNT FETs was found to be as good as Pd/CNT FETs.

Conclusions:

• Scandium contacts exhibit intrinsic scaling behavior suitable for advanced complementary CNT FET technology.
• Addressing Sc film oxidation is key to realizing the full potential of Sc contacts in scaled-down devices.
• Sc-contacted CNT FETs can meet the requirements for developing complementary CNT FET technology down to the 14 nm node.