Numerical simulation and primary validation for ion filtering capability of a dual grid installed in inductive coupled plasma

As semiconductor technology nodes continue to scale, etching processes must achieve atomic-level precision and ultra-low damage. Radical etching, owing to its advantage of being free from charge-induced damage, has emerged as a core technology for fabricating nano-structures with high selectivity and ultra-low damage. While radicals can be generated in low-temperature plasma sources, the coexisting ions, which cause surface damage and roughness, must be effectively filtered out. A single grid is the simplest ion-filtering device, but its limited capability of ion filtering does not meet requirements of the advanced semiconductor manufacturing. To tackle the issue, this paper proposes a dual-grid configuration targeted at enhancing ion-filtering efficiency without significantly increasing the system complexity. A two-dimensional simulation model was established to systematically investigate the influence of key parameters (e.g., grid spacing, aperture size) on ion-filtering efficiency and to identify the optimal dual-grid configuration. Experimental validation confirms that the optimally designed dual grid achieves an ion-filtering efficiency of up to 99.999%, a value that significantly surpasses the previously reported result.