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Ätzverfahren zum Materialabtrag an Festkörpern und dessen Verwendung sowie Vorrichtung hierzu

Removing material from solids, especially semiconductor wafers, employs liquid jet containing e.g. halogen compound which is irradiated to produce highly-reactive free radicals
: Mayer, K.; Kray, D.; Bauman, S.

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DE 102006019461 A: 20060426
DE 102006019461 A: 20060426
Patent, Elektronische Publikation
Fraunhofer ISE ()

(A1) Vorliegende Erfindung beschreibt ein Verfahren zum Materialabtrag an Festkörpern mittels mindestens einem Flüssigkeitsstrahl, der durch eine Düse erzeugt wird, bei dem zur Unterstützung des Materialabtrags ein aktivierbares Ätzmedium, das der Trägerflüssigkeit zugesetzt ist, aktiviert wird, wobei Aktivierung des aktivierbaren Ätzmediums nach Austritt aus der den Flüssigkeitsstrahl erzeugenden Düse erfolgt. Ebenso wird die Verwendung des Verfahrens sowie eine diesbezügliche Vorrichtung beschrieben.


DE 102006019461 A1 UPAB: 20080208 NOVELTY - An etchant capable of being activated, is added to the liquid jet (1). It is activated after leaving the nozzle which produces the jet. Activation is effected by irradiation using an annular radiation source (3) close to the jet. Irradiation is at right angles to the jet. A reflective surface (2, 2') at least part-surrounds the jet. Photo- and/or thermochemical activation takes place. Irradiation takes place in the W band of electromagnetic radiation, resulting in photochemical activation. DETAILED DESCRIPTION - Alternatively, infra red radiation promotes thermochemical activation. In a further variant, the visible waveband is used, causing photochemical activation. The light is incoherent and continuous, or it is pulsed. Ultraviolet light is provided by e.g. a mercury lamp, photodiode and/or a flash lamp. In addition, the location on the solid where the jet impinges, is irradiated using one of the above methods. The etchant is a water-free halogen- containing organic or inorganic compound or mixture. It is a straight chain, branched, aliphatic, cycloaliphatic and/or aromatic C1-C12 hydrocarbon which is at least partially halogenated. It is e.g. carbon tetrachloride, chloroform, bromoform, dichloromethane or a mixture of them. A wide range of further examples is specified in accordance with these principles, including diverse sulfur-, phosphorous- and ammonium compounds. Lewis-acids may be employed, especially boron trichloride or aluminum trichloride. The etchant includes at least one radical initiator, e.g. dibenzoyl peroxide or azo-isobutyronitrile. A radiation absorber is included, e.g. a dye, especially eosin, fluoroscene, phenolphthalein and/or Bengal red. It is alternatively a polycyclic aromatic compound, especially pyrene or napthacene. A solid body of silicon is used. AN INDEPENDENT CLAIM IS INCLUDED FOR corresponding apparatus. USE - To etch material from solids including semiconductor wafers, using an activated liquid jet. To cut, microstructure, dope solids, make local deposits, cut trenches and/or conduct metallization of solids or silicon wafers. (All claimed). Wafers may be cut from the single crystal by parallel jets. ADVANTAGE - The apparatus used, is not damaged by the etchant. This is because the etchant is not activated until after it has left the nozzle and is in flight. Virtually all of the activated etchant has sufficient life to reach and act upon the solid. Illumination of the jet at right angles, minimizes irradiation of and consequent undesired effects on the solid, avoiding problems of earlier laser-irradiation systems. Process efficiency is increased by mirrors, which are optionally elliptical, with the source at one focus, the jet at the other. Irradiation generates highly-reactive free radicals of e.g. chlorine, which etch silicon both directly and rapidly. Technical implementation is simple. Outstanding material removal is assured. Reactions are further discussed in the disclosure.