Atomic layer etching using metastables formed from an inert gas

Abstract

Substrate processing systems and methods for etching an atomic layer are disclosed. The methods and systems are configured to introducing a first gas into the chamber, the gas being an etchant gas suitable for etching the layer and allowing the first gas to be present in the chamber for a period of time sufficient to cause adsorption of at least some of the first gas into the layer. The first gas is substantially replaced in the chamber with an inert gas, and metastables are then generated from the inert gas to etch the layer with the metastables while substantially preventing the plasma charged species from etching the layer.

Description

Background technique [0001] Atomic layer etching is a technique known in the art for semiconductor device fabrication to perform critical etching with very fine precision. In atomic layer etching, etching is performed on thin layers while trying to avoid unnecessary subsurface damage or undesired modification. For example, atomic layer etching can be performed to etch a very thin layer covering another critical layer. Atomic layer etching may also be used, for example, when attempting to remove a layer at the end of a bulk etch step while ensuring that etching of the thin remaining layer does not result in damage to underlying layers and / or underlying structures. [0002] In particular, etching using plasma is known to have the potential to cause the aforementioned subsurface damage or modification to underlying structures and / or underlying layers. Silicon loss under the gate dielectric during plasma etch is an example of subsurface loss, i.e., even in thin gate dielectrics ...

AI Technical Summary

Problems solved by technology

In some cases, plasma etching with ion energies greater than 100 eV is known to result in damage to a depth of about 20-40 Angstroms below the surface

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