Investigations on elimination of plasma-induced Si substrate damage for 3D NAND fabrication

This paper presents the methods of eliminating the plasma-induced Si substrate damage in periphery regions, resulting from high aspect ratio etching process for 3D NAND fabrication. The impact of Si substrate damage is verified by the low and high bias power experiments. The result indicates more Si damage is present with high energy bombardment; therefore, high bias power is recommended to be inhibited unless necessary. The elimination of Si substrate damage is also confirmed with surface layer removal process. The damaged-layer is removed by Si recess procedure, and a healthy Si substrate can be obtained.