Description:
For next-generation semiconductor manufacturing, vertical ion-bombardment during plasma etching is a key factor in obtaining high performance devices. However, the ion trajectory on the wafer can vary owing to the physical discontinuity between the wafer termination and the focus ring. In this study, we developed a method to qualify the plasma etching result in highaspect-ratio trench with ion tilting by using the natural sheath curvature at the wafer edge. The experiment was investigated in a radio-frequency-biased inductively coupled plasma with an Ar/C 4 F 6 mixture. It is revealed that even a slight ion tilts (1–3°) induce large changes in etch characteristics, such as etch-stop, asymmetric and vertical etching, which strongly depend on the trench arrangement, location, and aspect ratio. These phenomena were analyzed using the relationship between the electric field angle (𝜃 E ) at the sheath curvature and the critical angle (𝜃 c ) for ions reaching the trench bottom. It was confirmed that: i) bottom etch stops when 𝜃 E >