CMOS-Compatible Fabrication Module for Sub-100 nm TiN and TaN Pillar Electrodes for Carbon Nanotube Test Structures

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Electrical Engineering

Background:

• Sub-100 nm pillar electrodes are crucial for advanced nanoelectronic devices.
• Existing fabrication methods often lack the precision and compatibility required for emerging technologies.
• Titanium nitride (TiN) and tantalum nitride (TaN) are key materials for these electrodes.

Purpose of the Study:

• To develop a versatile, CMOS-compatible fabrication module for sub-100 nm TiN and TaN pillar electrodes.
• To demonstrate the integration of these electrodes into carbon nanotube-based nonvolatile random-access memory (CRAM) test structures.
• To establish a reproducible platform for nanoscale electrode fabrication.

Main Methods:

• Electron beam lithography for high-resolution hydrogen silsesquioxane (HSQ) mask definition.
• Optimized Ar/Cl2 inductively coupled plasma reactive ion etching for TiN film transfer.
• Optical emission spectroscopy for real-time etch endpoint detection.
• Buffered hydrogen fluoride treatment for residual HSQ removal.
• Atomic force microscopy (AFM) and conductive AFM for characterization.

Main Results:

• Achieved reproducible sub-100 nm TiN and TaN pillar electrodes with smooth sidewalls and an average taper angle of ~77°.
• Demonstrated successful integration into CRAM test structures, showing preliminary switching behavior.
• Verified electrical conductivity and geometric fidelity of the fabricated nanoscale features.
• Showcased fabrication of TiN pillar arrays, TaN pillars, and TiN line arrays.

Conclusions:

• The developed fabrication module is versatile, CMOS-compatible, and capable of producing high-quality nanoscale TiN and TaN electrodes.
• The module provides a feasible platform for laboratory-scale research and development of emerging memory and nanoelectronic technologies.
• This work paves the way for future integration of advanced nanoelectronic devices.