Atomic layer etching has emerged as a viable approach to address the challenges associated with continuous or quasicontinuous plasma processes. To this end, the authors previously reported the quasiatomic layer etching of silicon nitride via sequential exposure to hydrogen and fluorinated plasma. The underlying premise was the surface modification via implantation of hydrogen ions into silicon nitride resulting in an anisotropic etch. In this paper, the authors will demonstrate that a similar enhancement in reactivity of silicon nitride can also be attained via diffusion of hydrogen atoms into silicon nitride with the resultant etch being isotropic. These results confirm the realization of self-limiting etch of silicon nitride with tunable directionality. Selectivity to oxide is >100 and damage to underlying silicon can be minimized by optimizing the flux of atomic fluorine during the exposure to fluorinated plasma. Thus, hydrogen plasma step controls the directionality while fluorinated plasma step determines the selectivity to oxide and underlying silicon.
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September 2017
Research Article|
July 13 2017
Quasiatomic layer etching of silicon nitride with independent control of directionality and selectivity
Sonam D. Sherpa;
Sonam D. Sherpa
TEL Technology Center, America, LLC
, 255 Fuller Road, Suite 214, Albany, New York 12203
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Peter L. G. Ventzek;
Peter L. G. Ventzek
Tokyo Electron America, Inc.
, 2400 Grove Blvd., Austin, Texas 78741
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Alok Ranjan
Alok Ranjan
a)
Tokyo Electron Miyagi, Ltd.
, 1 Techno-Hills, Taiwa-cho, Kurokawa-gun, Miyagi 9813629, Japan
and TEL Technology Center
, America, LLC, 255 Fuller Road, Suite 214, Albany, New York 12203
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a)
Electronic mail: alok.ranjan@tel.com
J. Vac. Sci. Technol. A 35, 05C310 (2017)
Article history
Received:
April 03 2017
Accepted:
June 26 2017
Citation
Sonam D. Sherpa, Peter L. G. Ventzek, Alok Ranjan; Quasiatomic layer etching of silicon nitride with independent control of directionality and selectivity. J. Vac. Sci. Technol. A 1 September 2017; 35 (5): 05C310. https://doi.org/10.1116/1.4993133
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