Highly anisotropic etching of submicrometer features on tungsten

We have investigated the anisotropic etching of submicrometer features (0.2–1 μm) on tungsten at substrate temperatures varying from −45 to +15 °C in a newly developed magnetoplasma reactor operated with SF6. In contrast to earlier reports, we have achieved such ultrafine pattern etching without external biasing, hence with low-energy ions, thus reducing possible damage to the substrate. We have observed highly anisotropic microscopically uniform etching at pressures lower than a threshold value which depends on the substrate temperature; above this threshold, the anisotropy decreases and the microscopic nonuniformity depends on linewidth and space pattern.