Exploring the influence of gas flow rate on surface charging issue during plasma etching.

The charging effect on the surface of two adjacent and rough mask holes has been studied during plasma etching, as functions of gas flow rate and ion incident energy E i based on classical particle dynamics simulations of surface charging, surface etching and profile evolution. This study revealed that, on the one hand, various gas flow rates can result in different distributions of the electric field (E-field) and the net charge density on the surface of the mask. Specifically, the overall E-field strength gradually fades with the increase is the gas flow rate. The E-field in the middle region of these two holes dramatically becomes weak with the gas flow rate, while changes are very small in the outer edges of holes. On the other hand, the simulated evolution of the mask profile exhibits an increased deformation as the gas flow rate increases. Conversely, this deformation decreases with increasing E i . Possible mechanisms of these results during the etching process were discussed. This work sheds light on the reduction of the mask pattern damage and further improves the quality of the pattern transferring onto the substrate. [ABSTRACT FROM AUTHOR]