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Plasma Etching and ALE

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During plasma processing it is important to maintain the optimum plasma conditions for the process.

Plasma diagnostics are critical in determining and maintaining this process window.


Atomic Layer Etching (ALE) is a two-step process which allows for reliable single atomic layer precision of the etch. The first step is to form a reactive layer on the substrate. The second step then removes this layer, and the underlying substrate layer, in a self-limiting manner. For the second step to be self-limited it is critical that the ion energy is higher than the sputtering threshold of the reactive layer but below that of the substrate layer.

Radical and ion fluxes are also important for the formation of the reactive layer.

The Hiden PSM or EQP can be used to monitor both the fluxes of radicals and ions and their energies in real time.

IEDs as a function of pressure in 1000W Ar.

CF radical densities measured using a QMS during one cycle of ALE at 100W and 300W of (a) CF (b) CF2 (c) CF3; (d) C2F4 and (e) F


Hiden Analytical produces a range of specialized tools for Plasma Etching & ALE. To find out more information about our industry-leading products, get in touch with Hiden Analytical today.

Further Reading

Description of HiPIMS plasma regimes in terms of composition, spoke formation and deposition rate

The behaviour of Cu and Cr HiPIMS (high power impulse magnetron sputtering) discharges was investigated by a combination of optical emission spectroscopy, energy-resolved mass spectrometry and optical imaging, for the complete current–voltage characteristic range achievable within our experimental conditions. Inflection points typical of HiPIMS current–voltage characteristics separate plasma regimes perfectly differentiated in terms of flux composition of species towards the substrate, deposition rate, and the nature of plasma self-organization. The reorganization of the HiPIMS plasma into spokes (areas of high ionization over the target) is associated to one regime of high plasma conductivity, where also deposition rate is limited. This spoke-dominated regime can be substituted by a homogeneous regime at higher powers, where there is an increase of deposition rate, which is driven mostly by an increase in the flux of metal neutrals and metal double-charged ions. The relevance of secondary electron emission mechanisms for the support of the spoke-dominated regime in reactive and non-reactive sputtering conditions is discussed.

Teresa de los Arcos, Raphael Schroder, Yolanda Aranda Gonzalvo, Volker Schulz-von der Gathen and Jorg Winter (Published 25 September 2014)

Online at: http://stacks.iop.org/0963-0252/23/054008 

  1. Vlček, J. et al. Magnetron sputtered Si–B–C–N films with high oxidation resistance and thermal stability in air at temperatures above 1500 °C. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 26, 1101–1108 (2008).
  2. Vlček, J. et al. Reactive magnetron sputtering of hard Si–B–C–N films with a high-temperature oxidation resistance. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 23, 1513–1522 (2005).
  3. Ehiasarian, A. P. et al. Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films. Journal of Applied Physics 109, 104314 (2011).