Share Email Print

Proceedings Paper

Dry-plasma-free chemical etch technique for variability reduction in multi-patterning (Conference Presentation)
Author(s): Subhadeep Kal; Nihar Mohanty; Richard A. Farrell; Elliott Franke; Angelique Raley; Sophie Thibaut; Cheryl Pereira; Karthik Pillai; Akiteru Ko; Aelan Mosden; Peter Biolsi

Paper Abstract

Scaling beyond the 7nm technology node demands significant control over the variability down to a few angstroms, in order to achieve reasonable yield. For example, to meet the current scaling targets it is highly desirable to achieve sub 30nm pitch line/space features at back-end of the line (BEOL) or front end of line (FEOL); uniform and precise contact/hole patterning at middle of line (MOL). One of the quintessential requirements for such precise and possibly self-aligned patterning strategies is superior etch selectivity between the target films while other masks/films are exposed. The need to achieve high etch selectivity becomes more evident for unit process development at MOL and BEOL, as a result of low density films choices (compared to FEOL film choices) due to lower temperature budget. Low etch selectivity with conventional plasma and wet chemical etch techniques, causes significant gouging (un-intended etching of etch stop layer, as shown in Fig 1), high line edge roughness (LER)/line width roughness (LWR), non-uniformity, etc. In certain circumstances this may lead to added downstream process stochastics. Furthermore, conventional plasma etches may also have the added disadvantage of plasma VUV damage and corner rounding (Fig. 1). Finally, the above mentioned factors can potentially compromise edge placement error (EPE) and/or yield.

Therefore a process flow enabled with extremely high selective etches inherent to film properties and/or etch chemistries is a significant advantage. To improve this etch selectivity for certain etch steps during a process flow, we have to implement alternate highly selective, plasma free techniques in conjunction with conventional plasma etches (Fig 2.). In this article, we will present our plasma free, chemical gas phase etch technique using chemistries that have high selectivity towards a spectrum of films owing to the reaction mechanism ( as shown Fig 1). Gas phase etches also help eliminate plasma damage to the features during the etch process. Herein we will also demonstrate a test case on how a combination or plasma assisted and plasma free etch techniques has the potential to improve process performance of a 193nm immersion based self aligned quandruple patterning (SAQP) for BEOL compliant films (an example shown in Fig 2). In addition, we will also present on the application of gas etches for (1) profile improvement, (2) selective mandrel pull (3) critical dimension trim of mandrels, with an analysis of advantages over conventional techniques in terms of LER and EPE.

Paper Details

Date Published: 27 April 2017
PDF: 1 pages
Proc. SPIE 10149, Advanced Etch Technology for Nanopatterning VI, 101490P (27 April 2017); doi: 10.1117/12.2257507
Show Author Affiliations
Subhadeep Kal, Tokyo Electron America, Inc. (United States)
Nihar Mohanty, Tokyo Electron America, Inc. (United States)
Richard A. Farrell, Tokyo Electron America, Inc. (United States)
Elliott Franke, Tokyo Electron America, Inc. (United States)
Angelique Raley, Tokyo Electron America, Inc. (United States)
Sophie Thibaut, Tokyo Electron America, Inc. (United States)
Cheryl Pereira, Tokyo Electron America, Inc. (United States)
Karthik Pillai, Tokyo Electron America, Inc. (United States)
Akiteru Ko, Tokyo Electron America, Inc. (United States)
Aelan Mosden, Tokyo Electron America, Inc. (United States)
Peter Biolsi, Tokyo Electron America, Inc. (United States)

Published in SPIE Proceedings Vol. 10149:
Advanced Etch Technology for Nanopatterning VI
Sebastian U. Engelmann, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?