Patterning of single-walled carbon nanotubes using a low-fluence excimer laser photoablation process

Abstract

Carbon nanotubes (CNTs) have been researched as a possible important new component in various devices because they have a promising potential in applications such as microelectronic devices, sensors, actuators and optoelectronic devices. For the use of CNTs in such applications, especially in mass fabrication, a pattering process for CNT layers that is compatible with CMOS (Complementary Metal Oxide Semiconductor) processes is necessary. There have been some reports in the literature on the patterning of CNTs, but either the reported methods were not compatible with CMOS processes or the capability for precise control of the pattern geometry was not good. In this paper we describe a new patterning method that can be used in the fabrication of devices and other applications which use carbon nanotubes as a component material. This method also can be used in the patterning of other highly porous materials. Further, the process is compatible with conventional microelectronic fabrication processes and it is high-speed. Single walled carbon nanotube (SWNT) films were patterned by an excimer laser projection photoablation process at low incident energy conditions. The CNTs were deposited on a quartz substrate, and then a conventional photoresist was coated on it as a photoablation assistor. The photoresist and the CNTs were patterned simultaneously by the photoablation process, and then the photoresist was removed. Due to the physical force of the ablation-dissociated photoresist fragments, the CNTs were patterned cleanly even though the incident fluence on them was significantly lower than the threshold energy otherwise needed for their direct ablation.