| AVS 66th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Thursday Sessions |
| Session PS+2D+EM+SS+TF-ThA |
| Session: | Plasma-Enhanced Atomic Layer Etching |
| Presenter: | Yoshihide Kihara, Tokyo Electron Miyagi Ltd., Japan |
| Authors: | Y. Kihara, Tokyo Electron Miyagi Ltd., Japan T. Katsunuma, Tokyo Electron Miyagi Ltd., Japan S. Kumakura, Tokyo Electron Miyagi Ltd., Japan T. Hisamatsu, Tokyo Electron Miyagi Ltd., Japan M. Honda, Tokyo Electron Miyagi Ltd., Japan |
| Correspondent: | Click to Email |
In recent years, with the progress of device miniaturization and increased challenges in the scale of integration of semiconductor devices, ultra-high selectivity and atomic layer-level critical dimension (CD) control techniques are required in the fabrication processes.
In the conventional etching, using a fluorocarbon (FC) gas, the high selectivity is obtained by taking advantage of the difference of the FC protective film thickness due to the difference of materials.[1] However, adopting the conventional approach to cutting-edge pattern structure becomes difficult due to the excessive FC film clogging the micro slit facet. To meet the highly complex requirements, alternative process was developed by using ion modification and chemical dry removal.[2] We have made several improvements on this new approach and applied it to SiN and SiC etching. The improved new approach achieves ultra-high selectivity without FC protective film and we also confirmed this process has the characteristics of a self-limiting reaction based on ion depth profile as well as ALE.
In the patterning processes, lower pattern densities have a larger CD shrinking due to micro-loading. Hence, we developed the new process flow that combines atomic layer deposition (ALD) technique and etching. With this method, we achieved CD shrinking at atomic-layer level precision for various patterns, without causing CD loading.[3]
Moreover, Quasi-ALE can etch the pattern while maintaining the mask CD for different pattern density. This is because Quasi-ALE precisely controls the surface reaction by controlling the radical flux and ion flux independently.[3] Also, it was necessary to control oval CD size between X and Y respectively. We found that X-Y CD control can be easily performed by changing the balance of FC adsorption and Ar desorption in Quasi-ALE. However, there are concerns about mask selectivity and ion damage in this approach. To solve these problems, we introduce the Advanced Quasi-ALE technique which combines mask protection together with Quasi-ALE. The Advanced Quasi-ALE achieves wider X-Y CD control margin.
On the other hand, as aspect ratio is increased in the memory fabrication process, the occurrence of bowing profile is a serious problem. To address the issue, the new improvement technique has been developed that combines the concept of ALD and etching. With this method, we are able to etch profile more vertically in high A/R feature.
Reference
[1] M. Matsui et al., J. Vac. Sci. Technol. A 19 1282 (2001)
[2] N. Posseme et al., Applied Physics Letters105 051605 (2014)
[3] M. Honda et al., J. Phys. D: Appl. Phys., Vol.50, No.23 (2017)