Etching with atomic precision by using low electron temperature plasma

• Published in: Journal of physics. D, Applied physics Applied physics, 2017-07, Vol.50 (27), p.274003
• Main Authors: Dorf, L, Wang, J-C, Rauf, S, Monroy, G A, Zhang, Y, Agarwal, A, Kenney, J, Ramaswamy, K, Collins, K
• Format: Article
• Language: English
• Subjects: atomic layer etch; atomic precision etch; low damage etch; low electron temperature plasma; low ion energy plasma
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/1361-6463/aa7357

There has been a steady increase in sub-nm precision requirement for many critical plasma etching processes in the semiconductor industry. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in conventional radio-frequency (RF) plasma processing systems, even during layer-by-layer or 'atomic layer' etch. To meet these increasingly stringent requirements, it is necessary to have an accurate control over ion energy and ion/radical composition during plasma processing. In this work, a new plasma etch system designed to facilitate atomic precision plasma processing is presented. An electron sheet beam parallel to the substrate surface is used to produce a plasma in this system. This plasma has a significantly lower electron temperature Te ~ 0.3 eV and ion energy Ei