Cryoetching

Christophe Cardinaud, Aurélie Girard, Cédric Mannequin [2022, ->], Ahmed Rhallabi Post-doctoral researcher :Felipe Cemin [2022-2023],Ahmad Mortada [2022-2022],  PhD Student Jack Nos [2021-2024]

In addition to the usual field of application in deep silicon etching, cryogenic processes appear promising today for the etching of various materials (semiconductors, their oxides and nitrides, low-permittivity materials, etc.) at nanometric pattern sizes and with the need to control the etched depth to the atomic layer (ALE - atomic layer etching).
One of the interests of cryo-ALE is in the fact that the species participating in the etching are, in the first step, physisorbed on the surface of the cold substrate and then react chemically with it during an argon plasma initiated in the second step. These steps are then repeated until the desired etching depth is reached.
Achieving these application objectives requires progress in the understanding of the physical and chemical mechanisms involved in the process.
To achieve these objectives, this study is conducted for silicon compounds (Si3N4 and SiO2) for different fluorinated gases on the Optimist platform connected by ultra-vacuum transfer to a XPS between -180°C and +100°C.

Keywords        Cyclic plasma etching, cryo-ALE, physisorption, selectivity.
Expertises       Fluorine-based plasmas SF6, CF4, C4F8, In situ surface characterisation: XPS
Collaborations      GREMI Orléans, TEL Tokyo et Albany, LTM Grenoble