Etch challenges and evolutions for atomic-order control

We introduce a state-of-the-art self-aligned contact (SAC) process and patterning process developed by new patterning technology using Atomic Layer Etch (ALE) and Atomic Layer Deposition towards 5/7nm generation. SAC process is known to require SiO
₂
etching capability with ultra-high selectivity to SiN. We developed Quasi-ALE technique to improve the ALE process to make it more suitable for SiO
₂
Etch. By adopting this technology to the SAC process, conventional trade-offs between fine process control and SiO
₂
selectivity to SiN in the fine slit pattern is significantly improved. This achievement is enabled by Quasi-ALE's independent controllability of the radical flux and ion flux, which precisely controls the reaction layer thickness on the surface, allowing etch process at lower ion energy region. On the other hand, in the patterning process, CD shrink technique without CD loading is one of the key requirements. By integrating the ALD [1] into the etching flow, we developed a process that can control the CD shrink quantity in the atomic layer level without causing CD loading. This is obtained by utilizing a conformal layer with characteristics of ALD's self-limiting reaction, which is independent of the pattern variety.