Study on charging and thermal effects for an asymmetric trench in plasma etching

This study investigates the relationship between charging effects on an asymmetric silicon dioxide trench (with only height asymmetry) considering the temperature factor and using a simulation approach. It is found that the electron–solid interaction must be involved due to the temperature-dependent extra energy provided by the trench material. First of all, the densities of the net positive and negative charges, which are primarily deposited at four vertices and at the bottom of the trench, respectively, and their intensity, exhibit an increasing trend with the temperature. Moreover, the density distribution of positive charges exhibits asymmetry between the vertices of the tall and short mask edges. The simulated profiles exhibit two distinct characteristics attributed to the temperature effect and the asymmetry of the trench. This study further reveals that the distance of the trench is also an important factor affecting the charging issues associated with temperature. For a small distance, there is a significant deposition of net positive charge on both sides of the trench, and the density is noticeably higher than that observed in other cases. The corresponding intensities of negative and positive potentials, which are primarily concentrated at the bottom and on the top surface of the trench, are observed to have linear and non-linear correlations with the temperature, respectively. The simulated profiles reveal that the extent of deformation displays a non-linear variation with the distance. It is foreseeable that this study holds significant value and will provide valuable insights for an enhanced mask design.