Computer modeling of plasmas and their surface processes, with experimental validation, for a better understanding of cryogenic etching.

Plasmas are widely used in the microelectronics industry for the fabrication of computer chips, during plasma etching and deposition of materials. Following Moore's law, much effort is put into continuously decreasing electronic feature dimensions. Indeed, typical feature sizes decreased from 10 μm in 1971 to 14 nm in 2014. The gradual shrinking of features thus entails a continuous improvement of the plasma processes. To go beyond 14 nm features, it is crucial to limit plasma induced damage during processing. Recently, one such novel process to limit plasma damage is cryogenic etching of low-k material with SF6/O2/SiF4 and CxFy plasmas. In this project, I wish to obtain a fundamental understanding of the plasma behavior and its interaction with the surface, for these gas mixtures, to improve cryogenic plasma etching. For this purpose, I will apply numerical models to describe (i) the plasma behavior for SF6/O2/SiF4 and CxFy gas mixtures, and (ii) the surface interactions of the plasma species with the substrate. The plasma behavior will be simulated by a hybrid Monte Carlo - fluid model for addressing the various plasma species (electrons, ions, neutrals and excited species). The interaction of the plasma species with the substrate surface will be described by additional Monte Carlo and molecular dynamics (MD) simulations, allowing a detailed insight in the microscopic trench etching process. Furthermore, I plan to validate the models by means of cryogenic etch experiments.

Keywords:MOLECULAR DYNAMICS, COMPUTER SIMULATIONS, PLASMA CHEMISTRY, PLASMA

Disciplines:Applied mathematics in specific fields, Classical physics, Physics of gases, plasmas and electric discharges, Inorganic chemistry, Organic chemistry, Theoretical and computational chemistry, Other chemical sciences