Quantitative Control of Plasma and Surface Reactions for Dielectric Film Etching

According to the IRDS, along with the progress of miniaturization in the future, technologies to control the processing at the atomic level to respond to new materials and new structures will be required. However, plasma and surface reactions are still often treated as black boxes in dry etching process control, and quantitative understanding and control of plasma processes will be more important for achieving high-precision processing. This paper briefly outlines the development history of dielectric film dry etching equipment and processes and describes what is required for processing at the atomic layer level. In the 1980s and 90s, the development of a plasma sources with a high ion flux to increase the etch rate of SiO₂, and a process that strictly controlled the number of electron collisions (τn_e<σv>) to suppress excessive dissociation of gas molecules to achieve high selectivity was established. With the advent of low-k materials to realize high-speed, low-power-consumption devices, around 2000, a model for more delicate control of surface reactions and techniques for predicting incident flux have been proposed. From 2010 onwards, techniques for predicting damage that cannot be observed with an electron microscope have been required. The energy distribution of incident ions and the penetration depth of high-energy ions and/or photons have been quantitatively controlled. More recently, there have been active discussions about SiO₂ ALE. In this process, however, since the reaction does not stop by self-limiting, it is necessary to predict and control the surface reaction when using plasma in the transient state before reaching the steady state. We believe that technologies such as plasma monitoring, modeling, and prediction technologies will be further improved, and future atomic-level manufacturing technologies will be realized.