| AVS 63rd International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS+TF-WeM |
| Session: | Atomic Layer Etching |
| Presenter: | Kazunori Shinoda, Hitachi, Japan |
| Authors: | M. Izawa, Hitachi High-Technologies Corp., Japan K. Shinoda, Hitachi, Japan N. Miyoshi, Hitachi, Japan H. Kobayashi, Hitachi, Japan N. Yasui, Hitachi High-Technologies Corp., Japan M. Tanaka, Hitachi High-Technologies Corp., Japan Y. Sonoda, Hitachi High-Technologies Corp., Japan K. Kuwahara, Hitachi High-Technologies Corp., Japan K. Ishikawa, Nagoya University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
With shrinking device size and introduction of 3D FinFET transistor structure, cyclic Atomic Layer Etching (ALEt) becomes one of the key technologies in thin film etch. To achieve extreme high selectivity against mask and etch-stop layers, atomic level etching as a method to meet these etching requirements and eliminate physical damage has been investigated. Further, isotropic ALEt will be required for use in nanoscale patterning for formation of more complex 3D structures. In cyclic ALE technology, a modification layer is formed on a thin film layer by supplying etching species. After that, the modification layer is removed by heating. We investigated two types of ALEt tools; one is a anisotropic ALE tool based on Microwave ECR plasma and the other is a isotropic ALE based on ICP type down-flow plasma.
Recently, we have reported results of isotropic ALEt of Silicon Nitride (SiN) film [1]. High-throughput and high-selectivity ALEt of SiN using IR irradiation and down-flow plasma was also demonstrated [2]. Modification layer, ammonium hexafluorosilicate ((NH4)2SiF6), was synthesized by fluorocarbon gas plasma and nitrogen supplied from SiN flim. Because the modification layer is formed only on SiN film, SiN film can be removed with high selectivity at IR radiation heating step. This technology can be also applicable to ALEt of TiN.
Anisotropic ALEt was also investigated by using Microwave-ECR plasma [3]. In this study, Ar ion irradiation was utilized instead of heating. To achieve high selectivity, the ion energy lower than sputtering threshold is required. Because microwave-ECR plasma has low plasma potential and is not fluctuated by wafer RF power, lower ion energy is available. In addition, It is known that excessive dissociation of gases and by-products causes reverse reaction and degradation of selectivity. We therefore used high gas flow rate and pulsed plasma to reduce dissociation. This ALEt technology has been applied to high selective etching of Si, HfO2, and SiN film.
[1] K. Shinoda et al., AVS Atomic Layer Etching workshop 2015.
[2] N. Miyoshi et al., 62 nd AVS, , PS+SS+TF-WeM5, 2015.
[3] M.Tanaka et al. , SPIE Advanced Litho., 9428-23, 2015.