WO2004104635A1 - Dispositif de detection de rayons x et procede de fabrication - Google Patents

Dispositif de detection de rayons x et procede de fabrication Download PDF

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Publication number
WO2004104635A1
WO2004104635A1 PCT/DE2004/001077 DE2004001077W WO2004104635A1 WO 2004104635 A1 WO2004104635 A1 WO 2004104635A1 DE 2004001077 W DE2004001077 W DE 2004001077W WO 2004104635 A1 WO2004104635 A1 WO 2004104635A1
Authority
WO
WIPO (PCT)
Prior art keywords
barrier layer
layer
detector elements
arrangement according
sensitive layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DE2004/001077
Other languages
German (de)
English (en)
Inventor
Jürgen Schreiber
Tilo Baumbach
Ole Hirsch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
Original Assignee
Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV filed Critical Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
Publication of WO2004104635A1 publication Critical patent/WO2004104635A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
    • G01T1/2914—Measurement of spatial distribution of radiation
    • G01T1/2921—Static instruments for imaging the distribution of radioactivity in one or two dimensions; Radio-isotope cameras
    • G01T1/2928—Static instruments for imaging the distribution of radioactivity in one or two dimensions; Radio-isotope cameras using solid state detectors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/301—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices being sensitive to very short wavelength, e.g. being sensitive to X-rays, gamma-rays or corpuscular radiation

Definitions

  • the invention relates to an arrangement for the detection of X-rays and a method for producing such arrangements. It can be used in a wide variety of areas of technology, such as non-destructive testing, in medical diagnostics, but also for many safety-related applications.
  • X-ray technology has been used for a long time and in the recent past developments have been made to use X-rays in conjunction with electronic evaluation as so-called digital X-ray pixel systems.
  • X-rays incident on them can be detected in a spatially resolved manner and a digital image can be made available in electronic form.
  • the electronic signal values obtained in this way can be stored and evaluated.
  • a visual representation is also immediately or later with a delay
  • a layer formed from polycrystalline mercury iodide can be coated on both sides, with semiconductor transistor elements as at least on one side of such a polycrystalline layer Thin film transistors have been formed.
  • EP 0 784 801 proposes using parals or humiseal for this purpose.
  • these substances have disadvantages because of their electrical properties and their limited protective action with regard to the electrode materials used and the chemically aggressive polycrystalline semiconducting materials, so that the signal-to-noise ratio is deteriorated and there are failures of individual flat areas on a detector system designed in this way, e.g. the so called "dark lines”.
  • At least one such passivation layer has to be formed by means of an additional manufacturing step that is different from other process technologies.
  • the arrangement according to the invention for the detection of X-rays has a sensitive layer made of a semiconducting material that absorbs X-rays.
  • This sensitive layer can be in the form of a planar structure and is bordered on two opposite sides.
  • a cover electrode made of an electrically conductive material is electrically conductively contacted with this layer, which is exposed to the incident X-ray or gamma radiation.
  • Such a cover electrode can also be designed as a closed flat element.
  • a barrier layer has been formed between the sensitive layer and the detector elements.
  • the layer thickness of this barrier layer can be limited to a few nanometers and should not exceed a maximum layer thickness of 500 nm, preferably 100 nm. There- it should be ensured that the barrier layer forms at least one closed layer, whereby this can already be achieved with a minimum layer thickness of 2 to 3 nm.
  • the negative influence of aggressive semiconducting materials with respect to the electrodes of materials forming semiconductor transistor elements can be completely prevented.
  • the electrical properties of a suitable barrier layer have a very advantageous effect on the sensitivity.
  • the extremely small required layer thickness of the barrier layer is particularly advantageous here, since a considerably increased electrical conductivity is achieved, starting from the sensitive layer in the direction of the detector elements.
  • barrier layer regions with increased electrical conductivity, which in turn are enclosed by separating webs.
  • Separators are either formed from a dielectric material or have a significantly increased specific electrical resistance compared to the barrier layer regions.
  • a corresponding barrier layer area is locally assigned to each detector element, and electrical separation is ensured by the separating webs and, if appropriate, additionally electrically insulating areas which are formed around the detector elements.
  • barrier layer areas can be dimensioned this way be that the ratio of their respective layer thicknesses in relation to a maximum area extension along an axis of at least 1: 150 can be maintained.
  • the ratio of the layer thickness to a surface diagonal of a barrier layer region formed in a square or rectangular shape can easily adhere to this ratio, wherein ratios of 1: 500 or even 1: 1000 are also possible.
  • the individual barrier layer areas should be adapted in surface shape and in their dimensions to the respective shape and size of the electrodes of detector elements assigned to them.
  • the individual detector elements with the barrier layer regions forming a detector array should be electrically insulated from one another in such a way that local crosstalk to neighboring elements can be prevented.
  • the specific electrical resistance of the amorphous carbon in the barrier layer regions can be in the range between 10 and 1000 ⁇ cm, this being able to be influenced by influencing various parameters during the deposition of such layers in a vacuum.
  • the proportions of graphitic carbon (Sp 2 ) and the proportions of diamond-like carbon (Sp 3 ) can be varied, the specific electrical resistance being able to be reduced as the Sp 2 proportion increases. With an increased Sp 3 content, the density of such a layer can be increased, which in turn means that a reduced layer thickness of such a barrier layer can be used.
  • a barrier layer can also by galvanic deposition of a suitable metal or a suitable metal alloy.
  • the deposition can take place directly on an array which is formed from detector elements.
  • a particularly suitable metal for this is palladium, which can also be electrodeposited in combination with nickel as a palladium-nickel alloy.
  • barrier layers When galvanically forming barrier layers, it is advantageous to subsequently planarize the surface of the barrier layer formed, to which the sensitive layer is then to be subsequently applied.
  • the planarization can be carried out, for example, by mechanical-chemical polishing.
  • a thin coating which consists of BCB, polyimide or another resistant polymer, on the galvanically deposited barrier layer.
  • webs made of a dielectric material can be used or formed.
  • Such webs can for example consist of Si0 2 or organic materials that have been obtained by means of photolithographic processes.
  • the webs can advantageously be formed from dielectric material when producing an array of a plurality of detector elements.
  • Such detector elements can have been designed in the form of conventional thin-film transistors.
  • the detector elements are complementary metal oxide semiconductor elements (CMOS). These are available as standard components, the individual CMOSs being able to be dimensioned very small and, accordingly, a very high spatial resolution capability can be achieved in an arrangement according to the invention. For example, maximum dimensions of individually detectable areas below an area size of 50 x 50 ⁇ m can be achieved. Each individual COMS can deliver a discrete measurement signal in direct form, so that high-resolution area detection can be achieved. However, higher functionality can also be achieved. In this way, an integrating measurement, a recording of individual events or an energy-dependent detection can be carried out.
  • Other semiconductor transistor elements such as thin-film ASICs, can also be used as detector elements.
  • the suitable detector elements are not limited to the designated semiconductor transistor elements.
  • ITO indium tin oxide
  • the surface of an array arrangement of semiconductor transistor elements can be leveled by means of BGB (bencocyclobutene).
  • the cover electrode already mentioned can have been formed directly on the surface of the sensitive layer as a metallic thin film.
  • a cover electrode from graphitic carbon.
  • an appropriate dispersion (Aquadag) is applied to the surface and, after drying, a closed cover electrode made of graphitic carbon is obtained.
  • This graphitic carbon can additionally covered with a thin metal layer, e.g. gold.
  • the sensitive layer can be formed from amorphous selenium or silicon, but also from mono- or polycrystalline materials.
  • a targeted selection of the layer thickness of the sensitive layer can also have been made for the various application possibilities of an arrangement according to the invention.
  • reduced layer thicknesses on sensitive layers which are used on arrangements according to the invention for medical diagnostics can be much smaller than in the case of arrangements which e.g. used in non-destructive material testing.
  • the arrangements according to the invention can be produced in such a way that surfaces of detector elements arranged discretely to one another, which if possible form a continuous array, are coated with a barrier layer made of diamond-like carbon in a vacuum.
  • a sensitive layer which consists of a polycrystalline, semiconducting material that absorbs X-ray or gamma radiation, is in turn applied.
  • an electrically conductive layer is formed on the surface of this sensitive layer as a cover electrode, which covers the entire surface of the sensitive layer. It is not necessary to structure such a cover electrode in a plurality of surface areas which are electrically insulated from one another.
  • the individual metallic barrier layer areas are separated from one another by separators made of dielectric material.
  • Such dielectric separators can be formed between the individual detector elements already during the manufacture of an array consisting of a plurality of detector elements.
  • the barrier layer is formed from diamond-like carbon in a vacuum
  • a pulsed plasma can be used, and graphite can be used as the target material.
  • the plasma can be produced in a manner known per se pulsed laser radiation, pulsed arc discharge or in combination, can be generated as a so-called laser-are process.
  • the sensitive layer and here in particular a sensitive layer, is composed of mercury iodide or lead iodide, as described in EP 0 784 801 B1.
  • the cover electrode can subsequently also be formed in vacuum as a metallic thin layer.
  • the sensitive layer can also be formed by a screen printing process.
  • the individual detector elements can then each individually, optionally with the interposition of
  • Gain stages can be connected to an electronic evaluation unit and in turn the individual signals can be stored, processed or displayed as an image for a visual evaluation.
  • the arrangement according to the invention is characterized in that a high sensitivity can be achieved with a simultaneously reduced spatial resolution, even with a significantly reduced X-ray intensity.
  • reliable long-term operation can be ensured without failure of individual detector elements or detection areas. It has a particularly favorable effect here that corresponding contacting methods, such as bonding or flip-chip technology, can be dispensed with.
  • Figure 1 shows in schematic form a structure of an example of an arrangement according to the invention.
  • detector elements 2 are formed discretely on one another as CMOS. These have a contact surface 2 'made of aluminum.
  • the barrier layer 4 which is formed from diamond-like carbon, is in turn arranged on this.
  • the barrier layer 4 has a thickness of 20 nm.
  • the aluminum contact surfaces 2 ' are separated here by webs 3 made of silicon dioxide, so that electrical insulation of the individual detector elements 2 is achieved.
  • a full-surface formation of a barrier layer 4 made of amorphous carbon was carried out and subsequently, using a laser beam, as an example of a suitable energy beam, a locally targeted influencing of the amorphous carbon of the barrier layer 4 performed.
  • a laser beam as an example of a suitable energy beam
  • electrically conductive barrier layer regions 4 ′ with an increased sp 2 component and separating webs 5 surrounding them with an increased sp 3 component can be formed.
  • the specific resistance of the carbon was increased to approx. 10 9 ⁇ cm and thus reached at least 10 5 ⁇ cm.
  • a sensitive layer 1 of mercury iodide was then formed.
  • a layer thickness of approx. 200 ⁇ m can be selected for medium X-ray energies.
  • Aquadag was applied to the sensitive layer 1 as a graphite dispersion, which can be achieved, for example, by screen printing or spin coating. After drying, the top electrode 7 was then formed from graphitic carbon.
  • such arrangements could be formed with a total area size of approx. 110 x 110 mm and an area resolution for the detection for individual pixels or pitches below 50 ⁇ m could be achieved.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Solid State Image Pick-Up Elements (AREA)
  • Measurement Of Radiation (AREA)
  • Light Receiving Elements (AREA)

Abstract

L'invention concerne un dispositif de détection de rayons X et un procédé de fabrication de celui-ci. Ledit dispositif peut être employé dans le test non destructif de matériaux, dans le diagnostic médical, ainsi que dans diverses applications de sécurité. L'invention vise à obtenir, à coûts réduits, une résolution élevée, un fonctionnement fiable à long terme, et une sensibilité augmentée. A cet effet, le dispositif selon l'invention comporte une couche sensible en matériau à semiconducteurs absorbant les rayons X. Sur un côté de la couche sensible, une électrode de couverture est mise en contact électrique, et l'autre côté comporte des éléments de détection isolés électriquement l'un par rapport à l'autre. Par ailleurs, la couche sensible, de préférence réalisée dans un matériau à semiconducteurs polycristallin, contient une couche barrière de préférence conçue en tant que couche de carbone amorphe. La couche barrière comporte des zones de couche barrière reliées électriquement à des éléments de détection individuels, séparées par des entretoises de séparation réalisées dans un matériau diélectrique ou présentant une résistance électrique supérieure.
PCT/DE2004/001077 2003-05-20 2004-05-19 Dispositif de detection de rayons x et procede de fabrication Ceased WO2004104635A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10323584A DE10323584B4 (de) 2003-05-20 2003-05-20 Anordnung zur Detektion von Röntgenstrahlung und Verfahren zu deren Herstellung
DE10323584.1 2003-05-20

Publications (1)

Publication Number Publication Date
WO2004104635A1 true WO2004104635A1 (fr) 2004-12-02

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PCT/DE2004/001077 Ceased WO2004104635A1 (fr) 2003-05-20 2004-05-19 Dispositif de detection de rayons x et procede de fabrication

Country Status (2)

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DE (1) DE10323584B4 (fr)
WO (1) WO2004104635A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0415541A1 (fr) * 1989-07-29 1991-03-06 Shimadzu Corporation Détecteur d'image radiative à base de semi-conducteur et sa méthode de fabrication
EP1045450A2 (fr) * 1999-04-13 2000-10-18 Agilent Technologies Inc. Réseau de capteurs d'image
WO2000072386A1 (fr) * 1999-05-19 2000-11-30 Commissariat A L'energie Atomique Dispositif de detection de rayonnement a forte dynamique
US6285029B1 (en) * 1998-07-27 2001-09-04 Imarad Imaging Systems Ltd. Semiconductor gamma-ray detector
US20020158207A1 (en) * 1996-11-26 2002-10-31 Simage, Oy. Forming contacts on semiconductor substrates for radiation detectors and imaging devices

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996010194A1 (fr) * 1994-09-29 1996-04-04 Yissum Research Development Company Of The Hebrew University Of Jerusalem Systeme de radiodetection et son procede de fabrication
US5498880A (en) * 1995-01-12 1996-03-12 E. I. Du Pont De Nemours And Company Image capture panel using a solid state device
EP0791230B1 (fr) * 1995-09-12 2008-08-13 Koninklijke Philips Electronics N.V. Capteur d'images radiographiques
US6060714A (en) * 1998-01-23 2000-05-09 Ois Optical Imaging Systems, Inc. Large area imager with photo-imageable interface barrier layer
IL143853A0 (en) * 2001-06-19 2002-04-21 Real Time Radiography Ltd Laminated radiation detector and process for its fabrication

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0415541A1 (fr) * 1989-07-29 1991-03-06 Shimadzu Corporation Détecteur d'image radiative à base de semi-conducteur et sa méthode de fabrication
US20020158207A1 (en) * 1996-11-26 2002-10-31 Simage, Oy. Forming contacts on semiconductor substrates for radiation detectors and imaging devices
US6285029B1 (en) * 1998-07-27 2001-09-04 Imarad Imaging Systems Ltd. Semiconductor gamma-ray detector
EP1045450A2 (fr) * 1999-04-13 2000-10-18 Agilent Technologies Inc. Réseau de capteurs d'image
WO2000072386A1 (fr) * 1999-05-19 2000-11-30 Commissariat A L'energie Atomique Dispositif de detection de rayonnement a forte dynamique

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Publication number Publication date
DE10323584A1 (de) 2004-12-30
DE10323584B4 (de) 2006-05-04

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