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Etching of HgCdTe compounds

Christophe Cardinaud, Aurélie Girard,  Post-doctoral researcher: Wilfrid Faider [2016-2017]

PhD: Jordan Piet (2019)

PROCEDE DE GRAVURE PAR PLASMA Gravure de composs semiconducteurs CdHgTe imageHg(1-x)CdxTe compounds are the materials of choice for the production of high-performance IR photodetectors, which have numerous fields of application, both in the military and civil fields.
In terms of etching, the challenge is to be able to produce patterns of micrometric dimension, with perfectly controlled geometry, in a stack of thin layers of Hg(1-x)CdxTe of variable composition (x). The depths concerned range from ~100 nanometres (electrical contact) to several micrometres (pixel definition). However, the processes used today induce defects which penalise the performance of the detectors: degradation of the electrical properties of the materials, modification of chemical composition, surface roughness, presence of residues, non-conforming pixel geometry
Our recent studies aim to explore new etching chemistries, alternatives to the "usual" CH4-H2-Ar mixture, with the objective of defining "soft" etching conditions that limit damage to the material as much as possible, while avoiding the deposition of a carbonaceous film.

Keywords         HgCdTe, Plasma etching, Infra-red photodetectors, CH4-H2 plasmas
Expertises       CH4-H2 and liquid organic molecules plasmas, In situ surface characterisation: XPS, ellipsometry, Plasma diagnostics: optical emission spectrometry, mass spectrometry, electrostatic probes.
Collaborations   CEA/Leti, DGA

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