| AVS 66th International Symposium & Exhibition | |
| Atomic Scale Processing Focus Topic | Thursday Sessions |
| Session AP+PS+TF-ThM |
| Session: | Thermal Atomic Layer Etching |
| Presenter: | Li-Hung Chen, Tokyo Electron Technology Solutions Limited, Japan |
| Authors: | L.H. Chen, Tokyo Electron Technology Solutions Limited, Japan T. Kato, Tokyo Electron Technology Solutions Limited, Japan K. Nakahata, Tokyo Electron Technology Solutions Limited, Japan K. Takeya, Tokyo Electron Technology Solutions Limited, Japan |
| Correspondent: | Click to Email |
As device features continuously shrink with introducing complex structures and new materials in semiconductor manufacturing, extremely high selectivity for etch processes have become more and more important. High selective chemical dry etch is developed utilizing a separated damage-free chemical removal chamber and sublimation chamber. The required selectivity is realized by using various chemistries and quantum mechanics analysis.
Firstly, HF/NH3 chemistry is used for oxide etch with high selectivity to SiN, Si, metals and resist. On the other hand, HF mono chemistry can etch SiN with high selectivity to oxide and Si. Quantum mechanics analysis revealed that NH3 combined with HF enhances the SiO2 reaction because of its lower activation energy. However, HF mono chemistry enhances the SiN reaction because of its lower activation energy than the oxide reaction1). Secondly, Gas A chemistry is introduced for etching low quality oxide with selectivity >50 to both high quality oxide and SiN. The reaction rate barrier determined by quantum mechanics shows that etch reactivity with ALD-oxide is higher than with Th-SiO2 and SiN in Gas A etch process. Furthermore, Si and SiGe etch are evaluated with different Gas B/C ratio. Etch amount of Si is increased with increasing Gas C flow which can reduce activation energy from quantum mechanics simulation. Moreover, SiGe etching amount is decreased with increasing Gas C flow. This means that selectivity between Si and SiGe can be precisely controlled by Gas flow ratio.
Various applications can be realized by utilizing chemical dry etch with specific chemistries. For oxide etch processes such as fin recess, air gap, hard mask removal and surface clean, HF/NH3 chemistry can be used to meet critical criteria such as oxide selectivity to Si, SiN, resist and metal. CIP HW is developed to enhance throughput with excellent etch selectivity and uniformity. Additionally, HF mono-gas (or F-containing treatment) can dope Fluorine (F) into oxide film which is confirmed by depth profile analysis of secondary ion mass spectrometry (SIMS), and F implantation is known for dielectric breakdown life time improvement2). Also, Gas A can be utilized in Silica oxide removal process, which requires high selectivity between low quality and high quality oxide. Finally, Si mandrel removal and Si or SiGe nanowire fabrication is introduced by controlling gas flow ratio. Further discussion will be presented on AVS 66th.
Reference
[1] T. Kato, et al., AVS 65th Int. Symp. & Exhibit. (2018)
[2] Y. Mitani, et al., Proc. Of IEEE P93-98 (1999)