Processes

Atomic Layer Etching – Changing the Art of the Possible

The society of vacuum coaters (SVC) deserves to be better known. It was founded in 1957 during a surge in the use of vacuum coating techniques such as sputtering and evaporation. The techniques go back a very long way: that man Edison filed a patent for coating phonograph cylinders in 1892 (It will never catch on). Did you know that the shiny surface inside your crisp packet is a vacuum coating, which helps keep water out? From anti-reflection coatings on glasses and screens, to the thinnest layers making up computing chips, these techniques are everywhere.

This week I will be speaking at the SVC-2017 meeting in Providence Rhode Island. Rhode Island in the spring – someone’s got to. These days the conference has broadened out to surface engineering of all kinds, and I’ll be speaking on Atomic Layer Etching (ALEt). Plasma Technology has been working on this for almost two years, and we have filed our own patent. A technique that can remove materials while leaving the underlying materials almost undamaged has attracted a lot of interest. Click here to find out more.

Plasma etching brings chemical gases such as chlorine into contact with surfaces, together with positive ion bombardment. The ions break up the surface, letting the reactive gases in. New volatile compounds form, which leave the surface, taking some of the solid with them. The etching can be very vertical, being enabled by positive ions which have been accelerated directly towards the surface. Atomic Layer Etching separates the chemical and ion bombardment steps in time: first the chemical dose adsorbs on the surface, and then a very low energy ion bombardment removes just the chemical dose plus the bound atoms from the solid. It’s slow, but ideal if you don’t want to mash up the surface. The picture below tells the story for silicon etching with a chlorine dose and argon ions:

ALEt Diagram
ALEt diagram for silicon etching with a chlorine dose and argon ions

For more information visit www.oxford-instruments.com/ASP or for any questions send an email to Plasma-marcoms@oxinst.com

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