(Invited) Advanced Plasma Etching Processing: Atomic Layer Etching for Nanoscale Devices

Plasma processes for deposition and etching are required for development of the next generation semiconductor devices. To achieve high performance of nanoscale devices, the continuous development of fabrication processes is necessary. An atomic layer etching (ALE) process achieves this continuous development, since the process has advantages such as more precise, higher controllability and repeatability. We have developed ALE process for SiO2 to achieve high controllability and repeatability. The ALE process is a cyclic process composed of two steps: a first step which deposits a fluorocarbon film on the SiO2 surface using an Ar/C4F8 plasma, followed by an O2 plasma etching step. The O2 plasma etching suppresses forming a carbon-rich film on the target material surface and maintains the chamber conditions by removing the fluorocarbon on the chamber walls. The ALE process for SiO2 exhibits high reproducibility and has the potential to allow uniform EPC values over large wafer surfaces.