Damage-Free Plasma Source for Atomic-Scale Processing

As atomic-scale etching and deposition processes become necessary for manufacturing logic and memory devices at the sub-5 nm node, the limitations of conventional plasma technology are becoming evident. For atomic-scale processes, precise critical dimension control at the sub-1 nm scale without plasma-induced damage and high selectivity between layers are required. In this paper, a plasma with very low electron temperature is applied for damage-free processing on the atomic scale. In plasmas with an ultralow electron temperature (ULET, T_e < 0.5 eV), ion energies are very low, and the ion energy distribution is narrow. The absence of physical damage in ULET plasma is verified by exposing 2D structural material. In the ULET plasma, charging damage and radiation damage are also expected to be suppressed due to the extremely low T_e. This ULET plasma source overcomes the limitations of conventional plasma sources and provides insights to achieve damage-free atomic-scale processes.