Hard Mask Open Tilting Improvement with Advanced Source Coil

When 3D NAND technology developing from 64pair to 96pair and 128pair. Increasing ON/OP pairs will create higher aspect-ratio structures requiring vertical profiles and no tilting and resulting in more challenges for Etch. The increasing gate stack pairs and thicker film thicknesses will also require an optimized hard mask etch. Hard masks etch also plays a role with the profile and tilting which will influence the ON and Slit etch. For Carbon hard mask etch, if the mask open profile is not vertical, it can impact the ON etch profile and worse case impact device properties. So, for vertical bow-free profiles and low/no tilting performance, Applied Materials® innovated Advanced Source Coil to improve the plasma uniformity and distribution to improve the profile and tilting performance. This paper details the structure, the principle, and the etch profile and tilting improvement as a result of the Advanced Source Coil.