Prof. Rémi Coquand Profile

Prof. Rémi Coquand

at CEA-LETI

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Author

Publications (4)

Proceedings Article | 10 April 2024 Poster

Impact of process parameters on grayscale MEEF

Ujwol Palanchoke, Florian Tomaso, Yorrick Exbrayat, Gaby Bélot, Marie-Line Pourteau, Ivanie Mendes, Juline Saugnier, Aurélien Fay, Sébastien Bérard-Bergery, Elodie Sungauer, Charlotte Beylier, Rémi Coquand, Arthur Bernadac

Proceedings Volume PC12956, PC129560Y (2024) https://doi.org/10.1117/12.3010850

KEYWORDS: 3D mask effects, Grayscale lithography, 3D modeling, Data modeling, 3D microstructuring, 3D acquisition, Semiconductors, Profilometers, Process control, Photoresist processing

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Proceedings Article | 13 March 2024 Presentation

Silicon nitride photonics: large scale integration and applications

Quentin Wilmart, Sylvain Guerber, Jonathan Faugier-Tovar, Eleonora Garoni , Laura Sauze, Lavinia Nistor, Ahmed Gharbi, Vincent Mathieu, Tristan Dewolf, Rémi Coquand, Christophe Lecouvey, Guillaume Rodriguez, Linda Gianini, Baptiste Routier, Leopold Virot

Proceedings Volume PC12889, PC128890C (2024) https://doi.org/10.1117/12.3001555

KEYWORDS: Silicon nitride, Quantum photonics, Thermography, Waveguides, Quantum sensing, Quantum computing, Physical vapor deposition, Photonic quantum computing, Optical sensing, Microwave radiation

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Proceedings Article | 1 May 2023 Presentation + Paper

Mask errors impact on grayscale lithography patterning

Ujwol Palanchoke, Gaby Bélot, Sébastien Bérard-Bergery, Juline Saugnier, Elodie Sungauer, Charlotte Beylier, Florian Tomaso, Marie-Line Pourteau, Ivanie Mendes, Rémi Coquand, Arthur Bernadac

Proceedings Volume 12497, 124970N (2023) https://doi.org/10.1117/12.2657600

KEYWORDS: Critical dimension metrology, 3D mask effects, Microlens, Design and modelling, Cadmium, Scanning electron microscopy, Semiconducting wafers, Error analysis, 3D acquisition, Grayscale lithography

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Proceedings Article | 26 March 2019 Presentation + Paper

Grayscale lithography process study for sub 5µm microlens patterns

Nacima Allouti, Pierre Chevalier, Sébastien Bérard-Bergery, Valérie Rousset, Benedicte Mortini, Patrick Quéméré, Florian Tomaso, Rémi Coquand

Proceedings Volume 10958, 1095809 (2019) https://doi.org/10.1117/12.2514712

KEYWORDS: Microlens, Photomasks, Grayscale lithography, Chromium, Lithography, Photoresist processing, Annealing, Oxygen, Optical lithography, Atomic force microscopy

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The advance in microlithography has greatly helped the development of micro optical elements. Large array of microlenses can now be fabricated in the same fashion as manufacturing of integrated circuit at low cost and high yield [1-2].
Because microlens array requires well-defined and continuous surface relief profile, special methods are needed to supplement the normal microlithography to produce those spherical structures [3]. Various techniques have been developed, and the most widely used is multi-step photolithography with thermal resist reflow. However, the alternative grayscale photolithography technique appears to be the one as the most flexible and versatile method [4].
Indeed, this approach is a one-level lithography process enabling the development of 3D profiles in a photoresist masking layer. In addition, with the need to maintain or improve image quality at an ever-smaller pixel size, grayscale technic can offer one way to compensate the loss of the photosensitive area by achieving zero-gap microlens. One other advantage of grayscale is the possibility to have, from a single lithography, objects of different shapes, but also at the same time of different sizes (especially heights); which is possible with classical lithography only by doing multi-patterning.
There are several options for performing grayscale lithography, for example the HEBS mask (high energy beam sensitive) which darkens under exposure to electrons. The option that has been chosen is to use a grayscale reticle, with varying chromium features densities that locally modulate the intensity of transmitted UV light. Being non-uniformly exposed, this allows the creation of a relief structure in the resist layer after development. The resist height after development depends on the intensity of the incident light, the exposure time and the contrast of the resist. So contrary to conventional lithography where the goal is to achieve straight resist pattern profiles, grayscale lithography enables the realization of progressive profiles, which requires smooth resist contrast curve. The other specificity of these resists is that they must crosslink without flowing.
In this paper, we evaluate resists from different suppliers to generate microlenses smaller than 5μm via a grayscale mask. The study consists in establishing the contrast curves of these resists according to different process parameters, giving the designer great control of grayscale levels that can be achieved for a given resist. Then, pattern various microlenses shapes in these resists to evaluate the residual resist thickness according to the gray levels. With the final objective of establishing a relationship between these contrast curves and the profile variations at the microlens level to compute a suitable and accurate grayscale mask [5].

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