Invited Paper TF-WeM3
Layer-by-layer Etching of LaAlSiOx
Wednesday, December 14, 2016, 8:40 am, Room Makai
| Session: |
Plasma-based Film Growth, Etching, & Processing |
| Presenter: |
Mitsuhiro Omura, Toshiba Corporation, Japan |
| Authors: |
M. Omura, Toshiba Corporation, Japan
K. Furumoto, Toshiba Corporation, Japan
K. Matsuda, Toshiba Corporation, Japan
T. Sasaki, Toshiba Corporation, Japan
I. Sakai, Toshiba Corporation, Japan
H. Hayashi, Toshiba Corporation, Japan
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| Correspondent: |
Click to Email |
With downscaling of metal-oxide-semiconductor (MOS) devices, high dielectric constant (high-k) oxide materials have been proposed as gate oxide, to reduce the gate leakage current. LaAlSiOx is one of the attractive candidates. In gate transistor fabrication, removal of high-k oxide films after gate electrode etching is a critical step for the formation of ohmic contacts on source and drain regions. Dry etching is a potential process to minimize the recess of the Si substrate which leads to the degradation of device performances. The conventional approach is to use an etching process with high selectivity to the Si substrate. Sasaki et al. have achieved a high LaAlSiOx-to-Si selectivity of 6.7 using C4F8/Ar/H2 plasma [1]. Another approach to reduce the Si substrate recess is precise control of etching depth using atomic layer etching (ALE) or layer by layer etching. ALE is defined to be an etching technique that uses sequential self-limiting reactions consisting of two steps, surface modification to form a reactive layer, followed by a removal step which takes off only this modified layer keeping the underlying film intact [2]. It is reported that by ALE using an energetic Ar beam and BCl3 gas in HfO2 etching, drain current and leakage current characteristics of MOSFET device improved, compared with conventional reactive ion etching (RIE) [3]. To control the etching depth of LaAlSiOx, layer by layer etching using a sequential process has been studied, focusing on the selective removal of surface modification layer and repeatability of the sequential process.
[1] T. Sasaki, K. Matsuda, M. Omura, I. Sakai, and H. Hayashi: Jpn. J. Appl. Phys. 54 (2015) 06GB03.
[2] K. J. Kanarik, T. Lill, E. A. Hudson, S. Sriraman, S. Tan, J. Marks, V. Vahedi, and R. A. Gottscho: J. Vac. Sci. Technol. A 33(2) (2015) 020802.
[3] J. B. Park, W. S. Lim, B. J. Park, I. H. Park, Y. W. Kim, and G. Y. Yeom: J. Phys. D: Appl. Phys. 42 (2009) 055202.