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Christophe Cardinaud, Aurélie Girard, Ahmed Rhallabi, Post-doctoral researchers : Ahmad Mortada [2022-2023], Guillaume Le Dain [2018-2020], Wilfrid Faider [2016-2017],
PhD student : Jack Nos [2021-2024],      PhDs: Thibaut Meyer (2019), Jordan Piet (2019)

Plasma etching allows the production of patterns with micrometric or nanometric dimensions in a material. It is one of the essential steps in the manufacturing processes of integrated circuits. Since its birth in the 1980s, its constant development has been one of the driving forces behind the tremendous growth of microelectronics, telecommunications and microsystem technologies. The performance of the end device (microprocessor, memory, sensor, etc.) is closely linked to the nature of the materials used, the size of the structures and the quality of the etched surfaces.
Our research concerns the fundamental aspects of reaction mechanisms: What species are formed in the plasma? How do they interact with the materials? What are the products of interaction? are the main questions guiding our studies. These, carried out by coupling experimental and modelling approaches, have two aims

  • the understanding the physicochemical mechanisms of etching,
  • the mastering of dimensional control, surface chemistry and physical properties of the etched patterns.

Keywords :         Plasma etching, Plasma-surface interaction
Expertises :         Etching processes involving cold RF low pressure plasmas, Plasma diagnostics, In situ surface characterisation  
Collaborations : CEA/Leti-Grenoble, DGA, GREMI-Orléans,  ISCR-Rennes, KPF-Pardubice, LTM-Grenoble, C2N-Palaiseau, IJL-Nancy

Presentation of etching equipments    Alcatel reactor       Optimist platform   Nextral reactor

Etching and surface caracterisation of Ge-Sb-Se chalcogenide materials

Christophe Cardinaud, Aurélie Girard, Ahmed Rhallabi

PhD : Thibaut Meyer (2019)

PROCEDE DE GRAVURE PAR PLASMA Gravure et caractrisation de surface de matriaux chalcognures imageThe chalcogenide materials (S, Se, Te) formed in association with the elements of columns 13 (Ga, In) 14 (Si, Ge) or 15 (As, Sb) have particular or remarkable properties: excellent transmission in the mid-infrared and optical non-linearity for amorphous phases, low resistivity for crystalline phases, phase transition under electrical or thermal stress, which open the way to applications in integrated optics or for non-volatile PCRAM memories.
Device manufacturing requires structuring the material at the micrometer or nanometer scale. This step is decisive since the functionality and performance of the component depends on the chemical and physical surface quality of the structure produced.
Our work is focused on the GeSbSe family; it concerns the characterisation of solid and thin film materials made from them as well as the study of etching processes in fluorine-based plasmas (SF6, SF6-Ar, SF6-O2) or in CH4-H2-Ar mixtures with the aim of developing the knowledge on the etching mechanisms, assessing the damage induced and the viability of the processes.

Keywords :            HgCdTe, Plasma etching, Infra-red photodetectors, CH4-H2 plasmas
Expertises :           Fluorine-based and CH4-H2 plasmas, In situ surface characterisation: XPS, ellipsometry, Plasma diagnostics: optical emission spectrometry, mass spectrometry, electrostatic probes.
Collaborations :    ISCR-Rennes, KPF-Pardubice



Etching of steel in chlorine-based plasmas: modelling and characterization.

Ahmed Rhallabi, Christophe Cardinaud, Aurélie Girard, Post-doctoral researcher : Guillaume Le Dain [2018-2020]

SPOT les2 AhmedThe ANR SPOT project aims to develop a reactive plasma etching process to pattern the surface of austenitic and martensitic type steel parts down to the submicron scale. The etchings give the structured metal parts reinforced and durable tribological properties, which can be used in severe environments. Candidates for the replacement of parts usually made of more noble non-recyclable material or covered with a hard thin layer (DLC, TiN), they will then ensure economic and ecological gain. In this context, we have developed an etching simulator of steel under ICP Cl2/Ar plasma. The multi-scale approach has the advantage of predicting the spatio-temporal evolution of structures etched through masks as a function of machine parameters. The chemical composition of different types of steel is taken into account in the cellular approach based on the Monte-Carlo method, which studies the etching kinetics under the fluxes of reactive neutral species and energetic ions. The effects of certain parameters, such as the chemical composition of steels and the probability of Cl adsorption, on certain etching properties such as roughness, lateral over-etching, etch rate were highlighted. Analyzes of etched steel surfaces by XPS will allow a better understanding of the interaction mechanisms between the active species from the plasma and the steel surface. This will help to develop a surface model based on the Monte-Carlo probabilistic technique consistent with experimental observations.

Keywords              Plasma, Etching, Modelling, Steel, Chlore
Collaborations      IGL, C2N, SILSEF



Christophe Cardinaud, Aurélie Girard, Post-doctoral researcher : Ahmad Mortada [2022-2023], PhD Student Jack Nos [2021-2024]

PROCEDE DE GRAVURE PAR PLASMA Gravure temprature cryognique image

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

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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