Controlling the spatial distribution of the electron beam using a grid with spatially varying mesh sizes in inductively coupled plasma.

The controllability of spatial electron beam distribution using the spliced grid is investigated. The radial distribution of the electron beam is measured for the grids with spatially different mesh sizes. First, the electron beam energy is higher under the grid with a finer mesh even though the spliced grid remains equipotential. This is because electron acceleration through the sheath under the grid is influenced by the mesh size. As the mesh becomes finer, the electron acceleration under the grid increases, leading to an increase in the electron beam energy. Second, the electron beam flux is higher for the coarser mesh compared with the finer mesh. This is due to differences in grid transparency and the potential barrier for electrons, both of which are associated with the mesh size. Finer meshes lead to more frequent electron-grid collisions. In addition, the increased potential barrier above the grid with the finer mesh limits electron transmission to the extraction region. By utilizing the mesh-size-dependent behavior of the electron beam, its spatial distribution can be effectively controlled. These results indicate that the uniformity of electron-assisted etching processes can be improved through the spliced grid.