Carbon Nanotube Synthesis for Integrated Circuit Interconnects

Résumé du livre

Based on their properties, carbon nanotubes (CNTs) have been identified as ideal replacements for copper interconnects in integrated circuits given their higher current density, inertness, and higher resistance to electromigration. Although at the laboratory level CNTs have proven their technical viability as interconnects, fabrication issues such as growing the desired type of CNTs in selected positions, at temperatures compatible with CMOS processing (below 500"C), and with the appropriate electrical connections, remain challenges that are hindering their introduction into industry. The purpose of this study was to develop the processes and understanding needed to establish CNTs as viable replacements for metal-based integrated circuit (IC) interconnects. Through over a thousand synthesis experiments using a dedicated thermal Chemical Vapor Deposition (CVD) system, a systematic approach was developed starting with growth of CNTs on insulating substrates, then moving to conducting substrates, and finally integrating CNT growth into insulating scaffolds with regularly spaced pores. The following results were achieved: Control of the type of carbon nanotubes grown using simple process parameter variations: By focusing on controlling catalyst morphology evolution to obtain dense and tall carpets of vertically-aligned CNTs on insulating substrates, we were able to tune the diameter and number of walls, by simply timing the introduction of a reducing agent (hydrogen) into the thermal process