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Proceedings Paper

Electron energy distribution control by fiat: breaking from the conventional flux ratio scaling rules in etch
Author(s): Alok Ranjan; Mingmei Wang; Sonam Sherpa; Peter Ventzek
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Paper Abstract

With shrinking critical dimensions, minimizing each of aspect ratio dependent etching (ARDE), bowing, undercut, selectivity, and within die uniformly across a wafer is met by trading off one requirement against another. The problem of trade-offs is especially critical. At the root of the problem is that roles radical flux, ion flux and ion energy play may be both good and bad. Increasing one parameter helps meeting one requirement but hinders meeting the other. Managing process by managing flux ratios and ion energy alone with conventional sources is not adequate because surface chemistry is uncontrollable. At the root of lack of control is that the electron energy distribution function (eedf) has not been controlled. Fortunately the high density surface wave sources control the eedf by fiat. High density surface wave sources are characterized by distinct plasma regions: an active plasma generation region with high electron temperature (Te) and an ionization free but chemistry rich diffusive region (low Te region). Pressure aids is segregating the regions by proving a means for momentum relaxation between the source and downstream region. “Spatial pulsing” allows access to plasma chemistry with reasonably high ion flux, from the active plasma generation region, just above the wafer. Low plasma potential enables precise passivation of surfaces which is critical for atomic layer etch (ALE) or high precision etch where the roles of plasma species can be limited to their purposed roles. High precision etch need not be at the cost of speed and manufacturability. Large ion flux at precisely controlled ion energy with RLSATM realizes fast desorption steps for ALE without compromising process throughput and precision.

Paper Details

Date Published: 17 March 2015
PDF: 11 pages
Proc. SPIE 9428, Advanced Etch Technology for Nanopatterning IV, 94280O (17 March 2015); doi: 10.1117/12.2086604
Show Author Affiliations
Alok Ranjan, TEL Technology Ctr., America, LLC (United States)
Mingmei Wang, TEL Technology Ctr., America, LLC (United States)
Sonam Sherpa, TEL Technology Ctr., America, LLC (United States)
Peter Ventzek, Tokyo Electron America Inc. (United States)

Published in SPIE Proceedings Vol. 9428:
Advanced Etch Technology for Nanopatterning IV
Qinghuang Lin; Sebastian U. Engelmann; Ying Zhang, Editor(s)

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