Laser-assisted deposition of thin films from gas-phase and surface-adsorbed molecules

Herman, Irving P.

doi:10.1021/cr00096a005

Cited by 192 publications

(71 citation statements)

References 113 publications

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“…En el primer tipo de proceso, (capa C0 2 -silano), cuando se utiliza una mezcla de SiH 4 -NH 3 'y para activar la mezcla un láser IR (C0 2 , 10,6 fxm en continuo), tiene lugar un calentamiento del gas, alcanzándose valores lo suficientemente elevados para que se produzca la pirólisis del silano (E act = 52 kcal/mol), mientras el amoníaco NH 3 (E act = 92 kcal/mol) reacciona con los productos descompuestos en la fase gaseosa, formando aminosilanos intermedios (Si x N y H z ) (9). Estas capas, en general, tienen un alto índice de refracción (Tabla I) y un alto contenido de hidrógeno y silicio comparado con el nitrógeno (10), como confirman los espectros de infrarrojo (Fig.l, …”

Section: Capas Originalesunclassified

“…Posteriormente, el silano reacciona con los productos de la descomposición del amoníaco para producir aminosilanos (9). Estas capas tienen un valor del índice de refracción n = 1.8, típico de un nitruro de silicio (11) y son ricas en hidrógeno y nitrógeno, lo cual es evidente por la relativa abundancia de los grupos N-H (N-H y NH 2 ) y Si-H (Si-H y Si-H 2 ) que se observan en el espectro infrarrojo (Fig.l, …”

Section: Espectro I A)unclassified

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Capas de a-SiN:H modificadas mediante la irradiación con un láser de excímero

Banerji¹,

Serra²,

Chiussi³

et al. 1998

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Resumen Utilizando una mezcla de silano/amoníaco o disilano/amoníaco se obtuvieron capas de nitruro de silicio amorfo hidrogenado (a-SiN:H) mediante depósito químico en fase vapor asistido por láser C0 2 y ArF, ambos en configuración paralela. Estas capas se sometieron a irradiación con un láser excímero de ArF en atmósfera inerte. Las variaciones, tanto en su composición química como en su índice de refracción y morfología superficial se estudiaron sistemáticamente mediante espectroscopia infrarroja por transformada de Fourier (FTIR), espectroscopia dispersiva de rayos X (EDS), elipsometría y microscopía de fuerzas atómicas (AFM), respectivamente. Las modificaciones observadas involucran por una parte una gran reducción, con los primeros pulsos de irradiación, del hidrógeno enlazado (Sili y N-H), acompañado por una progresiva incorporación de oxígeno (Si-0 y Si-OH) y una reducción de los enlaces Si-N. Este comportamiento se atribuye a la fotoquímica inducida por la radiación ultravioleta, donde el agua incorporada eri las capas, entre sucesivas irradiaciones, desempeña un papel muy importante. La comparación entre las diferentes capas indica que la cantidad de hidrógeno enlazado en las capas y su morfología superficial influyen en la resistencia de las mismas a la oxidación.Palabras clave: LCVD. Capa delgada. Nitruro de silicio. Irradiación. Láser ArF. a-SiN:H films modified by ArF excimer láser irradiation AbstractHydrogenated amorphous silicon nitride (a:SiN:H) films produced by C0 2 and ArF laser-induced CVD in parallel configuration using silane/ammonia or disilane/ammonia gas mixtures were subjected to room temperature múltiple pulse ArF excimer láser irradiations in an inert gas atmosphere. Modifications in their chemical composition, refractive index, and surface morphology were systematically followed up through Fourier-transform infrared spectroscopy (FTIR), energy dispersive x-ray spectroscopy (EDS), single wavelength ellipsometry and atomic forcé microscopy (AFM), respectively. The observed film modifications involving large reductions in hydrogen (Si-H and N-H ) with the first few shots accompanied by a progressive incorporation of oxygen (Si-0 and Si-OH) and a reduction of Si-N bonds that are attributed to UV-induced photochemistry where the atmospheric water incorporated in the films between successive irradiations plays an important role.Comparison among the different films indicated that the extent of bonded hydrogen in the films and their surface morphology influence their oxidation resistance.

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Section: Capas Originalesunclassified

Section: Espectro I A)unclassified

Capas de a-SiN:H modificadas mediante la irradiación con un láser de excímero

Banerji¹,

Serra²,

Chiussi³

et al. 1998

REVMETAL

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“…Using light as a source of energy to drive deposition reactions has been studied for many years (Herman 1989;Haigh and Aylett 1988). The outcome of these studies has indicated that there are three typical routes for the deposition to occur.…”

Section: Depositionmentioning

confidence: 99%

“…Compound semiconductor deposition is "very complex and poorly understood" (Herman 1989). As with the elemental semiconductors, photo-induced thermal deposition can be used to produce GaAs, and GaP semiconductors as well as the ternary III-V semiconductors: GaAsP, AlGaAs, and InGaAs.…”

Section: Iii-v Semiconductorsmentioning

confidence: 99%

High-flux solar photon processes: Opportunities for applications

Steinfeld¹,

Coy²,

Herzog³

et al. 1992

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EXECUTIVE SUMMARYThe overall goal of this study was to identify new high-flux solar photon (HFSP) processes which show promise of being feasible and in the national interest. Electric power generation and hazardous waste destruction were excluded from this study at sponsor request.Our specific objectives were: * to survey pertinent information bases; · to construct and assemble in prescribed electronic form a bibliography of relevant literature; * to prepare an initial list of potentially promising HFSP applications; to define a set of criteria for evaluating potential HFSP applications; * to carry out more detailed evaluations of some of the more promising applications; · to provide recommendations on HFSP process applications indicating special promise; * to discuss the status of current relevant research; and * to recommend research needed to advance basic understanding of HFSP applications and to further their potential for practicality.Our approach was to carry out the project with a core team of researchers providing expertise over a broad array of foundational topics, viz., chemical physics, optics, spectroscopy, photochemistry, high-temperature reactions, industrial chemistry, and chemical process engineering. Because of the wide range of scientific and engineering disciplines relevant to the study goals and the relatively short time available for the study, members of the core team carried out intense, round-table discussions with invited experts in a diverse sphere of pertinent disciplines, e.g., pure and applied optics, solar energy, furnace design, combustion, materials science and engineering, etc. Core team members conferred with experts at the Solar Energy Research Institute (SERI) (now known as the National Renewable Energy Laboratory, NREL) and the University of Chicago, and with participants in related studies being conducted by the National Academy of Sciences and SRI International, Inc. PC-compatible software was used to carry out an in-depth survey of post-1985 literature and to assemble in electronic form a bibliographic data base of important publications. Our approach emphasized the importance of delineating critical scientific and engineering foundations for identifying, evaluating, and discriminating among potentially promising options for HFSP applications. For example, limitations on solar photon intensity and wavelength and temporal variations in solar insolation impact process capacity, duty cycle, and controllability. Competition from alternative sources of intense photon fluxes was also considered in some detail. Formal economic and engineering cost estimates were outside our charter, but the study noted the importance of considering both conventional and externalized factors (e.g., environmental impacts, national security, global competitiveness, quality of fossil or other energy displaced) in determining overall costs of HFSP and competing options.Our overall conclusion is that there is promise for new applications of concentrated solar photons, especially in certain aspects of ...

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“…These laser forward transfer techniques, known as laser direct-write (LDW), belong to a class of processes capable of generating a high-resolution pattern without the need for lithogaphic processes afterwards. Other examples of laser direct-write techniques include pyrolitic or photolytic decomposition of gas-or liquid-phase precursors, also known as laser CVD or laser-assisted deposition (Osgood, 1985;Herman, 1989). However, these non-forward transfer techniques will not be discussed in this chapter because they are not ablative in nature.…”

Section: Introductionmentioning

confidence: 99%