Spin-on siloxane polymers in image sensor applications

Tässä työssä esitellään siloksaani-pohjaisten spin-on polymeerien tuomia etuja CMOS-kuvakennojen toimintaan. Ensimmäisessä osassa tutustutaan valon perusominaisuuksiin ja kuinka se käyttäytyy kulkiessaan väliaineessa sekä rajapintojen yli. Lisäksi käydään läpi nykyisin yleisimmin käytössä olevien kuvakennojen toimintaa sekä rakennetta. Työn kokeellisessa osuudessa tullaan osoittamaan mitä etuja siloksaani-pohjaisilla polymeereillä on kennojen valmistuksessa tavallisesti käytettyihin eristekerroksiin verrattuna. Työn aikana tutkittiin erityisesti Silecsin valmistamien korkean taitekertoimen spin-on polymeerikalvojen soveltuvuutta kennon valokanavarakenteeseen. Parannukset erityisesti pieniä pikseleitä hyödyntävien CMOS-kuvakennojen kvanttihyötysuhteeseen sekä pikselien väliseen ylikuulumiseen havainnollistetaan sekä optisen mallinnuksen että käytännön mittausten avulla. IBM:n 2.2 µm pikselikoon CMOS-kuvakennossa saavutettiin valokanavarakenteen avulla 24% parannus kvanttihyötysuhteessa ja 19% parannus ylikuulumisessa. Lisäksi työssä arvioidaan matalan taitekertoimen omaavien polymeerikalvojen soveltuvuutta kennojen passivointiin ja heijastuksenestoon. Havaittiin, että mikrolinssin pinnasta syntyviä heijastuksia pystyttiin merkittävästi vähentämään säätämällä kalvon paksuus ja taitekerroin sovellukseen sopivaksi. Lopuksi havainnollistetaan suorakuvioitavien polymeerien tuomia etuja kennon valmistusprosessiin.The feasibility of siloxane based spin-on polymers in a complementary metal oxide semiconductor (CMOS) image sensor application is studied in this thesis. After an introduction to the fundamental characteristics of light and how it behaves when propagating in matter and through interfaces, the basic operation principles of the most commonly used modern image sensors are reviewed. The experimental part of the thesis will demonstrate the improvements achieved in image sensor performance when replacing conventional dielectrics with siloxane based polymers having specifically tuned refractive indices. Results from optical modelling as well as measurement data from fully functional devices are used to demonstrate the enhanced device performance. Silecs' high refractive index spin-on polymers are shown to significantly improve the quantum efficiency and reduce crosstalk of a small pixel size image sensor utilizing a lightpipe structure. Up to 24% quantum efficiency and 19% crosstalk improvement was achieved in an IBM 2.2 µm pixel size sensor when comparing to a conventional structure. Silecs' low refractive index polymer films used as passivation and anti-reflection coatings on the image sensor microlens array were also studied. Lower reflectance from the microlens surface was achieved by properly tuning the overcoat film thickness and refractive index. Additionally, the overcoat provides mechanical protection to the soft microlens material which can result in improved manufacturing yield. Finally, photosensitized siloxane polymers are demonstrated to yield excellent photopatternability with using industry standard lithographic techniques

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Laser Micromachining: An Enabling Technology for Functional Surfaces and Materials

L'abstract è presente nell'allegato / the abstract is in the attachmen

Filtrage spectral plasmonique à base de nanostructures métalliques adaptées aux capteurs d'image CMOS

Image sensors have experienced a renewed interest with the prominent market growth of wireless communication, together with a diversification of functionalities. In particular, a recent application known as Ambient Light Sensing (ALS) has emerged for a smarter screen backlight management of display-based handheld devices. Technological progress has led to the fabrication of thinner handsets, which imposes a severe constraint on light sensors' heights. This thickness reduction can be achieved with the use of an innovative, thinnest and entirely on-chip spectral filter. In this work, we present the investigation and the demonstration of plasmonic filters aimed for commercial ALS products. The most-efficient filtering structures are identified with strong emphasis on the stability with respect to the light angle of incidence and polarization state. Integration schemes are proposed according to CMOS compatibility and wafer-scale fabrication concerns. Plasmon resonances are studied to reach optimal optical properties and a dedicated methodology was used to propose optimized ALS performance based on actual customers' specifications. The robustness of plasmonic filters to process dispersions is addressed through the identification and the simulation of typical 300 mm fabrication inaccuracies and defects. In the light of these studies, an experimental demonstration of ALS plasmonic filters is performed with the development of a wafer-level integration and with the characterization and performance evaluation of the fabricated structures to validate the plasmonic solution.Les capteurs d'image connaissent un regain d'intérêt grâce à la croissance remarquable du secteur de la communication sans fil, et leurs fonctionnalités tendent à se diversifier. Plus particulièrement, une application récente connue sous le nom de capteur de luminosité ambiante (ALS de l'acronyme anglais) est apparue dans le but de proposer un ajustement intelligent du rétro-éclairage dans les appareils mobiles pourvus d'écrans. Les avancées technologiques ont permis la fabrication de smartphones toujours plus fins, ce qui impose une contrainte importante sur la hauteur des capteurs de lumière. Cette réduction d'épaisseur peut être réalisée grâce à l'utilisation de filtres spectraux innovants, plus fins et entièrement sur puce. Dans cette thèse, nous présentons l'étude et la démonstration de filtres plasmoniques adaptés à une intégration dans des produits ALS commerciaux. Les structures de filtrage les plus performantes sont identifiées avec une importance particulière accordée à la stabilité des filtres par rapport à l'angle d'incidence de la lumière et à son état de polarisation. Des schémas d'intégration compatibles CMOS et respectant les contraintes d'une fabrication à l'échelle du wafer sont proposés. Les résonances de plasmon sont étudiées afin d'atteindre des propriétés optiques optimales et une méthodologie spécifique à partir d'un véritable cahier des charges client a été utilisée pour obtenir des performances ALS optimisées. La robustesse des filtres plasmoniques aux dispersions de procédé est analysée à travers l'identification et la modélisation des imprécisions et des défauts typiques d'une fabrication sur wafer 300 mm. A la lumière de ces travaux, une démonstration expérimentale de filtres ALS plasmoniques est réalisée avec le développement d'une intégration à l'échelle du wafer et avec la caractérisation et l'évaluation des performances des structures fabriquées afin de valider la solution plasmonique

Integral Optics: Lecture Notes

An introduction is given to the principles of integrated optics and optical guided-wave devices. The characteristics of dielectric waveguides are summarized and methods for their fabrication are described. An illustration is given of recent work on devices including directional couplers, filters, modulators, light deflectors, and lasers. The textbook reflects the latest achievements in the field of integrated optics, which have had a significant impact on the development of communication technology and methods for transmitting and processing information

Glassy Materials Based Microdevices

Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries. The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome