WO2017213622A1 - Grille intégrée de scintillateur à photodiodes - Google Patents

Grille intégrée de scintillateur à photodiodes Download PDF

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Publication number
WO2017213622A1
WO2017213622A1 PCT/US2016/036054 US2016036054W WO2017213622A1 WO 2017213622 A1 WO2017213622 A1 WO 2017213622A1 US 2016036054 W US2016036054 W US 2016036054W WO 2017213622 A1 WO2017213622 A1 WO 2017213622A1
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WIPO (PCT)
Prior art keywords
array
layer
grid holes
grid
silicon wafer
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PCT/US2016/036054
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English (en)
Inventor
Madhukar B. Vora
Brian Rodricks
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Terapede Systems Inc.
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Priority to PCT/US2016/036054 priority Critical patent/WO2017213622A1/fr
Priority to CN201710138113.1A priority patent/CN109342465B/zh
Publication of WO2017213622A1 publication Critical patent/WO2017213622A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/2018—Scintillation-photodiode combinations
    • G01T1/20188—Auxiliary details, e.g. casings or cooling
    • G01T1/20189—Damping or insulation against damage, e.g. caused by heat or pressure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14629—Reflectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H01L27/14658—X-ray, gamma-ray or corpuscular radiation imagers
    • H01L27/14663—Indirect radiation imagers, e.g. using luminescent members
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/03—Investigating materials by wave or particle radiation by transmission
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/10—Different kinds of radiation or particles
    • G01N2223/101—Different kinds of radiation or particles electromagnetic radiation
    • G01N2223/1016—X-ray
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/50—Detectors
    • G01N2223/505—Detectors scintillation

Definitions

  • the present disclosure relates to X-ray imaging and, more particularly, to an integrated scintillator grid with photodiodes.
  • Solid-state digital X-ray detectors also referred to as X-ray sensors, of an X-ray imaging system can be constructed by employing either of two physical detection methods, so- called direct and indirect conversion methods.
  • a direct conversion method makes use of direct production of electrons by X-rays in elemental compounds such as amorphous silicon or selenium, lead oxide, lead iodide, thallium bromide, or various gadolinium compounds. In this case, the electrons are collected via electric fields and electrodes attached to thin film transistors.
  • an indirect conversion method employs conversion of X-ray interactions to flashes of light in well-known scintillating materials such as thallium-activated cesium iodide or gadolinium oxysulfate.
  • the light flashes are sensed by photodiodes, and the resulting electron currents are again collected by attached transistor electronics.
  • FIG. 1 is a cross-sectional view of a structure of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with an embodiment of the present disclosure.
  • FIG. 2 is a cross-sectional view of a structure of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with another embodiments of the present disclosure.
  • FIG. 3A is a cross-sectional view of a structure of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with yet another embodiments of the present disclosure.
  • FIG. 3B is an enlarged view of the dash-lined portion of the structure of FIG. 3 A.
  • FIG. 4A is a cross-sectional view of an optical guide structure in accordance with an embodiment of the present disclosure.
  • FIG. 4B is an enlarged view of the dash-lined portion of the optical guide structure of FIG. 4A.
  • FIG. 5A shows a cross-sectional view of a structure of an integrated scintillator grid with photodiodes of an X-ray imaging system during a fabrication process in accordance with an embodiment of the present disclosure.
  • FIG. 5B shows a cross-sectional view of the structure of FIG. 5 A in a subsequent stage of the fabrication process in accordance with an embodiment of the present disclosure.
  • FIG. 5C shows a cross-sectional view of the structure of FIG. 5B in a subsequent stage of the fabrication process in accordance with an embodiment of the present disclosure.
  • FIG. 5D shows a cross-sectional view of the structure of FIG. 5C in a subsequent stage of the fabrication process in accordance with an embodiment of the present disclosure.
  • FIG. 6 is a top view and a cross-sectional view of a structure of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with still another embodiments of the present disclosure.
  • FIG. 7A is a cross-sectional view of a conventional X-ray imaging system in operation.
  • FIG. 7B is a cross-sectional view of another conventional X-ray imaging system in operation.
  • FIG. 8 is a cross-sectional view of an X-ray imaging system in accordance with an embodiment of the present disclosure in operation.
  • FIG. 9 is a flowchart of a fabrication process of a structure of an integrated scintillator grid with photodiodes in accordance with an embodiment of the present disclosure.
  • FIG. 1 illustrates a structure 100 of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with an embodiment of the present disclosure.
  • structure 100 includes a silicon wafer 102.
  • Silicon wafer 102 may include a device layer 104, an insulator layer 106 and a handle substrate 108.
  • silicon wafer 102 may be a silicon-on-insulator (SOI) wafer with a layer of buried oxide, which may be insulator layer 106.
  • thickness of the handle substrate 108 may be approximately 500 microns.
  • thickness of the buried oxide of the SOI wafer may be approximately 2500 angstroms.
  • device layer 104 may be an epi layer and may have a thickness of approximately 6 microns.
  • Device layer 104 may have an array of photodiodes constructed therein. That is, an array of photodiodes may be provided in device layer 104 on a first side (e.g., the top side of silicon wafer 102 shown in FIG. 1) of silicon wafer 102. The following description of a given photodiode of the array of photodiodes applies to each photodiode of the array. As shown in FIG. 1, each photodiode of the array of photodiodes may include a p region 126 formed in an n epi region 128 to form a PN diode. A contact diffusion of p+ impurities may be formed as a p+ region 124.
  • n+ isolation regions may be placed in n epi region 128 to isolate a depletion region 130 formed around the PN diode.
  • depletion regions 130 are indicated by dashed lines around the p region 126.
  • Structure 100 may additionally include an array of metal contacts 120 each of which is aligned with and corresponds to a respective photodiode of the array of photodiodes. Additionally, contacts 122 may be formed between the metal contacts 120 and photodiodes so that each photodiode is electrically connected to the respective metal contact 120.
  • Handle substrate 108 may have an array of grid holes 116 constructed therein. That is, an array of grid holes 116 may be provided in handle substrate 108 on a second side (e.g., the bottom side of silicon wafer 102 shown in FIG. 1) of silicon wafer 102. Grid holes 116 may be etched into the second side of silicon wafer 102 by any suitable process. In some embodiments, width of each grid hole 116 may be approximately 90 microns or more and thickness of sidewalls 114 of grid holes 116 may be approximately 10 microns or more. A layer of scintillating material 110 may be disposed over the array of grid holes 116 on the second side of silicon wafer 102 to cover up the array of grid holes 116.
  • a layer of reflective material 112 may be disposed on the layer of scintillating material 110.
  • scintillating material 110 may include CsLTa or Gaddox.
  • reflective material 112 may include aluminum (Al).
  • an object may be placed between an X-ray source and an X-ray imaging system in which the structure 100 of an integrated scintillator grid with photodiodes is implemented. Incident X-rays on the X-ray imaging system will mirror the nature of the object. Dense parts of the object tend to absorb significant amount of the X-rays and lighter parts of the object tend to let through most of the X-rays. As a result, spatial distribution of the X-ray dose represents the image of the object.
  • X-rays 140 coming through an object are radiated on the second side (e.g., the bottom side) of silicon wafer 102.
  • X-rays 140 will go through the layer of reflective material 112 and go into the layer of scintillating material 110 up to a distance D measured from an interface between the layer of reflective material 112 and the layer of scintillating material 110.
  • Distance D depends on the type of scintillating material 110 used. When CsLTA is utilized in scintillating material 110 the distance D may be approximately 300 microns. Thickness of the scintillating material 110 in FIG.
  • each of the PN diodes may be designed such that most of the light is absorbed in the depletion layer 130 above and around the PN diode. Light photon in the depletion layer 130 will generate electron-hole pairs.
  • the electric field in the depletion region 130 will cause holes 146 (shown as “h” in FIG. 1) to travel towards p region 126, p+ region 124 and contact 122, thereby generating photocurrent at a fixed bias voltage.
  • This current can be sensed and can be related to incident X-ray radiation.
  • An alternative way to sense X-ray photons is to pre-charge the PN diodes with a fixed voltage, such as 2.0V for example, through a MOS transistor prior to radiating with X-rays and turn off the MOS transistor, before radiating with X-rays.
  • a fixed voltage such as 2.0V for example
  • Light generated by the scintillating material 110 will be converted to hole-electron pairs and the PN diodes will start discharging to a voltage level corresponding to the incident light 144 or X-rays 140.
  • the voltage on the PN diode can be sensed and amplified using more MOS transistors.
  • a sense chip having an array of sensing circuits as described above may be formed over the first side (e.g., top side) of silicon wafer 102 such that each sensing circuit of the array of sensing circuits is configured to sense an electrical signal in a respective photodiode of the array of photodiodes corresponding to electron-hole pairs in the respective photodiode caused by light absorbed by the respective photodiode.
  • Each sensing circuit along with its corresponding photodiode may form a pixel.
  • Silicon wafer 102 which an array of photodiodes in the device layer 104 and an array of grid holes 116 in the handle substrate 108, may be referred to as a photo chip hereinafter.
  • Each pair of photodiode and its corresponding grid hole 116 may be referred to as a photo pixel hereinafter.
  • the circuit needed to pre-charge and sense the electrical signal in a corresponding photodiode may be referred to as sense pixel hereinafter.
  • An array of sense pixels along with peripheral circuits to select and sense the electrical signals, e.g., voltage, generated by photodiodes is placed on top of the array of photo pixels so that all the photodiodes under the sense chip are addressed by all the sense pixels in the sense chip.
  • Each sense pixel may include a contact pad that is aligned to a contact pad in the corresponding photo pixel that is connected to the respective photodiode. Thus, a sense pixel is connected to photo pixels.
  • X-rays 140 When X-rays 140 are radiated as shown in Figure 1, it is converted into light 142 by the layer of scintillating material 110 and in turn light 144 traveling through each grid hole 116 is converted to electron-hole pairs in the respective photodiode under the grid hole 116. Electron-hole pairs will recombine in the photodiodes and a voltage corresponding to X-rays 140 or light 144 in the grid hole will be generated.
  • Sense chip may be designed to sense electrical signals, e.g., voltage, from all the photodiodes, convert the sensed electrical signals into digital data and stream the digital data out to a digital signal processor (DSP) for signal processing and generation of an image of the object.
  • DSP digital signal processor
  • the proposed scheme provides a number of advantages over conventional designs of the X-ray detector or sensor in an X-ray imaging systems. Firstly, structure 100 as shown in FIG. 1 does not require filling of the grid holes 116. Secondly, while the X-ray-to-light conversion efficiency is about 6% for conventional designs in which grid holes are filled with scintillating material, the proposed scheme can result in an X-ray-to-light conversion efficiency of more than 50%. Moreover, the proposed scheme can achieve very high modular transfer function or contrast.
  • FIG. 2 is a cross-sectional view of a structure 200 of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with another embodiments of the present disclosure.
  • Structure 200 may be similar or identical to structure 100 in various aspects and, thus, detailed description of structure 200, except for any difference, is not provided in the interest of brevity.
  • the grid holes are filled with a filler material 216.
  • filler material 216 may be a transparent solid material such as, for example, silicon dioxide (S1O2), polyimide coatings or any transparent glass. This feature provides firmness to the silicon wafer of structure 200 for mechanical handling.
  • filler material 216 may be a scintillating material such as, for example, CsLTa.
  • the scintillating material e.g., CsLTa
  • CsLTa may be deposited in the grid holes by evaporation or by melting powder CsI:Ta.
  • an additional layer of CsLTa may be deposited over the array of filled grid holes.
  • about 300 microns of CsLTa may be deposited in the grid holes and additional 300 microns of CsLTa may be deposited on the top of the array of filled grid holes.
  • One main advantage of this feature is that CsLTa in the grid holes will pick up X-rays that have not been absorbed in the CsLTa layer that is deposited over the array of filled grid holes.
  • FIG. 3A is a cross-sectional view of a structure 300 of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with yet another embodiments of the present disclosure.
  • FIG. 3B is an enlarged view of the dash-lined portion 302 of structure 300.
  • Structure 300 may be similar or identical to structure 100 in various aspects and, thus, detailed description of structure 300, except for any difference, is not provided in the interest of brevity.
  • silicon sidewalls 304 of the grid holes are coated with a cladding material 306 with suitable refractive index.
  • the grid holes are filled with appropriate glass 308 to form a structure similar to fiber optic cable. This design will improve the light transmission through the grid holes significantly.
  • FIG. 4A is a cross-sectional view of an optical guide structure 400 in accordance with an embodiment of the present disclosure.
  • FIG. 4B is an enlarged view of the dash-lined portion 402 of optical guide structure 400.
  • optical guide structure 400 includes a silicon wafer 402.
  • Silicon wafer 402 may have an array of grid holes 406 constructed therein. Grid holes 406 may be etched into silicon wafer 402 by any suitable process. In some embodiments, width of each grid hole 406 may be approximately 90 microns or more and thickness of sidewalls 404 of grid holes 406 may be approximately 10 microns or more.
  • a layer of scintillating material 408 may be disposed over the array of grid holes 406 to cover up the array of grid holes 406. Additionally, a layer of reflective material 410 may be disposed on the layer of scintillating material 408. In some embodiments, scintillating material 408 may include CsLTa or Gaddox. In some embodiments, reflective material 410 may include aluminum.
  • silicon sidewalls 404 of grid holes 406 are coated with a cladding material 412 with suitable refractive index.
  • Grid holes 406 may be filled with appropriate glass 414 to form a structure similar to fiber optic cable. This design will improve the light transmission through the grid holes 406 significantly.
  • FIGS. 5 A - 5D show a cross-sectional view of a structure 500 of an integrated scintillator grid with photodiodes of an X-ray imaging system during a fabrication process in accordance with an embodiment of the present disclosure.
  • Structure 500 may be similar or identical to structure 100 (grid holes not filled) or structure 200 (grid holes filled with filler material) in various aspects and, thus, detailed description of structure 500, except for any difference, is not provided in the interest of brevity.
  • structure 500 includes a silicon wafer.
  • Silicon wafer may include a device layer, an insulator layer and a handle substrate.
  • silicon wafer may be a SOI wafer with a layer of buried oxide, which may be insulator layer.
  • Device layer may have an array of photodiodes constructed therein. That is, an array of photodiodes may be provided in device layer on a first side (e.g., the top side of silicon wafer shown in FIG. 5A) of silicon wafer.
  • Handle substrate may have an array of grid holes constructed therein. That is, an array of grid holes may be provided in handle substrate on a second side (e.g., the bottom side of silicon wafer shown in FIG.
  • a layer of scintillating material such as CsLTa or another scintillating material, is deposited on the back side of the silicon wafer.
  • thickness of the layer of scintillating material may be 300 microns.
  • the layer of scintillating material is etched to form an array of scintillators (or islands of scintillating material) isolated from each other such that each scintillator covers a respective grid hole of the array of grid holes.
  • a layer of poly(p-xylylene) polymers (not shown), such as Parylene, may be deposited to protect the scintillating material from moisture. Parylene is the trade name for a variety of chemical vapor deposited poly(p-xylylene) polymers used as moisture and dielectric barriers.
  • a layer of reflective material such as aluminum or another suitable material, is deposited over the array of scintillators.
  • aluminum can reflect light back into grid holes thereby increasing the light that enters the grid holes.
  • aluminum reduces loss of light going sideways.
  • aluminum blocks the light in a given grid hole going to neighboring grid hole(s).
  • FIG. 6 shows a top view and a cross-sectional view of a structure 600 of an integrated scintillator grid with photodiodes of an X-ray imaging system in accordance with still another embodiments of the present disclosure.
  • Structure 600 may be similar or identical to structure 100 (grid holes not filled) or structure 200 (grid holes filled with filler material) in various aspects and, thus, detailed description of structure 500, except for any difference, is not provided in the interest of brevity.
  • thickness "a" of handle substrate of the SOI wafer is approximately 300 microns
  • thickness "b" of the layer of scintillating material is approximately 200 microns.
  • a holding ring may be utilized to contain the layer of scintillating material, e.g., CsLTa, therein.
  • FIG. 7A is a cross-sectional view of a conventional X-ray imaging system 710 in operation.
  • an X-ray pulse in the scintillator may scatter in a wide scattering angle (represented by the two angled lines with arrows) and be sensed by any one of the photo sensors within the scattering angle.
  • the detected image of an object may have less-than ideal resolution and may be blurry.
  • FIG. 7B is a cross-sectional view of another conventional X-ray imaging system 720 in operation.
  • an X-ray pulse in the scintillator within sidewalls of a collimating structure e.g., grid holes
  • This design tends to have a less-than-optimal X-ray-to-light conversion efficiency.
  • FIG. 8 is a cross-sectional view of an X-ray imaging system 800 in accordance with an embodiment of the present disclosure.
  • X-ray imaging system 800 may utilize a structure similar to any of structures 100, 200, 300 and 500 as well as optical guide structure 400 as described above.
  • each of incoming X-ray pulses has a relatively wider scattering angle when in the scintillator and a relatively narrower scattering angle when within the collimating structure, e.g., grid holes. This design results in optimal X-ray-to-light conversion efficiency.
  • FIG. 8 is a cross-sectional view of an X-ray imaging system 800 in accordance with an embodiment of the present disclosure.
  • X-ray imaging system 800 may utilize a structure similar to any of structures 100, 200, 300 and 500 as well as optical guide structure 400 as described above.
  • each of incoming X-ray pulses has a relatively wider scattering angle when in the scintillator and a relatively narrower scattering angle when within the collimating structure,
  • Process 900 is a flowchart of a fabrication process 900 of a structure of an integrated scintillator grid with photodiodes in accordance with an embodiment of the present disclosure.
  • Process 900 wholly or partially, may be implemented to fabricate any of structures 100, 200, 300 and 500 as well as optical guide structure 400 as described above. Further, process 900 may include one or more operations, actions, or functions depicted by one or more blocks 10, 920, 930, 940, 950 and 960. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation.
  • process 900 may form an array of photodiodes on a first side of a silicon wafer.
  • process 900 may form an array of photodiodes, which are electrically isolated from each other, in a device layer on a first side of a silicon wafer.
  • process 900 may form an array of grid holes on a second side of the silicon wafer opposite the first side.
  • process 900 may form an array of grid holes on a second side of the silicon wafer opposite the first side thereof, with each grid hole of the array of grid holes aligned with a respective photodiode of the array of photodiodes.
  • process 900 may dispose a layer of scintillating material over the array of grid holes on the second side of the silicon wafer.
  • process 900 may dispose a layer of reflective material on the layer of scintillating material.
  • process 900 may form an array of sensing circuits configured to sense electrical signals in the photodiodes.
  • process 900 may form an array of sensing circuits such that each sensing circuit of the array of sensing circuits is configured to sense an electrical signal in a respective photodiode of the array of photodiodes corresponding to electron- hole pairs in the respective photodiode caused by light absorbed by the respective photodiode.
  • process 900 may bond the array of sensing circuits to the array of photodiodes.
  • process 900 may bond the array of sensing circuits to the array of photodiodes on the first side of the silicon wafer such that each sensing circuit of the array of sensing circuits is electrically connected to the respective photodiode.
  • the silicon wafer may include a silicon-on-insulator (SOI) wafer.
  • SOI silicon-on-insulator
  • the grid holes on the second side of the SOI wafer may reach an insulator of the SOI wafer.
  • the scintillating material may include CsLTa.
  • the reflective material may include aluminum (Al).
  • the method in disposing the layer of scintillating material over the array of grid holes, may perform operations including: filling the grid holes with the scintillating material; and depositing the layer of scintillating material over the array of grid holes which are filled with the scintillating material.
  • a thickness of the layer of scintillating material may be greater than or equal to a depth of the grid holes.
  • the method may further include filling the grid holes with a filler material.
  • the filler material may include a transparent solid material.
  • the transparent solid material may include silicon dioxide (Si0 2 ), polyimide, or glass.
  • the filler material may include a scintillating material.
  • the scintillating material may include CsLTa.
  • the method may further include, prior to filling the grid holes with the filler material, coating a layer of refractive material on sidewalls of the grid holes.
  • the method may further include, prior to disposing the layer of reflective material on the layer of scintillating material, etching the layer of scintillating material into an array of scintillators such that each scintillator of the array of scintillators is physically separate from each other and covers a respective grid hole of the array of grid holes.
  • the method may further include depositing a layer of poly(p-xylylene) polymers on the array of scintillators.
  • a structure implemented in an X-ray imaging system may include a silicon wafer.
  • the silicon wafer may include a first side and a second side opposite the first side.
  • the silicon wafer may also include an array of photodiodes on the first side of the silicon wafer with the photodiodes electrically isolated from each other.
  • the silicon wafer may further include an array of grid holes on the second side of the silicon wafer. Each grid hole of the array of grid holes may be aligned with a respective photodiode of the array of photodiodes.
  • the structure may also include a layer of scintillating material disposed over the array of grid holes on the second side of the silicon wafer.
  • the structure may further include a layer of reflective material disposed on the layer of scintillating material.
  • the silicon wafer may include a silicon-on-insulator (SOI) wafer.
  • SOI silicon-on-insulator
  • the grid holes on the second side of the SOI wafer may reach an insulator of the SOI wafer.
  • the scintillating material may include CsLTa.
  • the reflective material may include aluminum (Al).
  • the grid holes may be filled with a filler material.
  • the filler material may include a transparent solid material.
  • the transparent solid material may include silicon dioxide (Si0 2 ), polyimide, or glass.
  • the filler material may include a scintillating material.
  • the scintillating material may include CsLTa.
  • a thickness of the layer of scintillating material may be greater than or equal to a depth of the grid holes.
  • the structure may further include a layer of refractive material on sidewalls of the grid holes.
  • the layer of scintillating material may include an array of scintillators such that each scintillator of the array of scintillators is physically separate from each other and covers a respective grid hole of the array of grid holes.
  • the structure may further include a layer of poly(p- xylylene) polymers deposited on the array of scintillators.
  • the structure may further include an array of sensing circuits.
  • Each sensing circuit of the array of sensing circuits may be electrically connected to the respective photodiode.
  • Each sensing circuit of the array of sensing circuits may be configured to sense an electrical signal in a respective photodiode of the array of photodiodes corresponding to electron-hole pairs in the respective photodiode caused by light absorbed by the respective photodiode.
  • a structure implemented in an X-ray imaging system may include a silicon wafer.
  • the silicon wafer may include a first side and a second side opposite the first side.
  • the silicon wafer may also include an array of grid holes on the second side of the silicon wafer. Each grid hole of the array of grid holes may be aligned with a respective photodiode of the array of photodiodes.
  • the structure may also include a layer of scintillating material disposed over the array of grid holes on the second side of the silicon wafer.
  • the structure may further include a layer of reflective material disposed on the layer of scintillating material.
  • the silicon wafer may include a silicon-on-insulator (SOI) wafer.
  • SOI silicon-on-insulator
  • the grid holes on the second side of the SOI wafer may reach an insulator of the SOI wafer.
  • the scintillating material may include CsLTa.
  • the reflective material may include aluminum (Al).
  • the grid holes may be filled with a filler material.
  • the filler material may include a transparent solid material.
  • the transparent solid material may include silicon dioxide (Si0 2 ), polyimide, or glass.
  • the filler material may include a scintillating material.
  • the scintillating material may include CsI:Ta.
  • a thickness of the layer of scintillating material may be greater than or equal to a depth of the grid holes.
  • the structure may further include a layer of refractive material on sidewalls of the grid holes.
  • the layer of scintillating material may include an array of scintillators such that each scintillator of the array of scintillators is physically separate from each other and covers a respective grid hole of the array of grid holes.
  • the structure may further include a layer of poly(p- xylylene) polymers deposited on the array of scintillators.
  • a method of fabricating an X-ray imaging system may include: forming an array of photodiodes, which are electrically isolated from each other, in a device layer on a first side of a silicon wafer; forming an array of grid holes on a second side of the silicon wafer opposite the first side thereof, each grid hole of the array of grid holes aligned with a respective photodiode of the array of photodiodes; disposing a layer of scintillating material over the array of grid holes on the second side of the silicon wafer; disposing a layer of reflective material on the layer of scintillating material; forming an array of sensing circuits such that each sensing circuit of the array of sensing circuits is configured to sense an electrical signal in a respective photodiode of the array of photodiodes corresponding to electron-hole pairs in the respective photodiode caused by light absorbed by the respective photodiode; and bonding the array of sensing circuits to the array of photod
  • the silicon wafer may include a silicon-on-insulator (SOI) wafer.
  • SOI silicon-on-insulator
  • the grid holes on the second side of the SOI wafer may reach an insulator of the SOI wafer.
  • the scintillating material may include CsLTa.
  • the reflective material may include aluminum (Al).
  • the method in disposing the layer of scintillating material over the array of grid holes, may perform operations including: filling the grid holes with the scintillating material; and depositing the layer of scintillating material over the array of grid holes which are filled with the scintillating material.
  • a thickness of the layer of scintillating material may be greater than or equal to a depth of the grid holes.
  • the method may further include filling the grid holes with a filler material.
  • the filler material may include a transparent solid material.
  • the transparent solid material may include silicon dioxide (Si0 2 ), polyimide, or glass.
  • the filler material may include a scintillating material.
  • the scintillating material may include CsLTa
  • the method may further include, prior to filling the grid holes with the filler material, coating a layer of refractive material on sidewalls of the grid holes.
  • the method may further include, prior to disposing the layer of reflective material on the layer of scintillating material, etching the layer of scintillating material into an array of scintillators such that each scintillator of the array of scintillators is physically separate from each other and covers a respective grid hole of the array of grid holes.
  • the method may further include depositing a layer of poly(p-xylylene) polymers on the array of scintillators.
  • terms such as “above”, “below”, “upper”, “lower”, “top”, “bottom”, “horizontal”, “vertical” and “side”, for example, describe positions relative to an arbitrary axis of an element.
  • the terms “above” and “below” refer to positions along an axis, where “above” refers to one side of an element while “below” refers to an opposite side of an element.
  • the term “side” refers to a side of an element that is displaced from an axis, such as the periphery of the element, for example.

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Abstract

Les divers modes de réalisation, selon la présente invention, concernent une structure mise en œuvre dans un système d'imagerie par rayons X. Selon un aspect de la présente invention, une structure mise en œuvre dans un système d'imagerie par rayons X comporte une tranche de silicium comprenant un premier côté et un deuxième côté, opposé au premier côté. La tranche de silicium comprend également un réseau de photodiodes sur le premier côté de la tranche de silicium, les photodiodes étant électriquement isolées les unes des autres ainsi qu'un réseau de trous de grille sur le deuxième côté de la tranche de silicium. Chaque trou de grille du réseau de trous de grille est aligné avec une photodiode respective du réseau de photodiodes. La structure comprend également une couche de matériau scintillant disposée sur le réseau de trous de grille sur le deuxième côté de la tranche de silicium. La structure comprend en outre une couche de matériau réfléchissant disposée sur la couche de matériau scintillant.
PCT/US2016/036054 2016-06-06 2016-06-06 Grille intégrée de scintillateur à photodiodes WO2017213622A1 (fr)

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CN110416347A (zh) * 2019-07-30 2019-11-05 深圳大学 一种数字x射线图像探测器及其制备方法
CN110504278A (zh) * 2019-08-28 2019-11-26 无锡中微晶园电子有限公司 一种防串流光敏二极管芯片及其制造方法
CN110514682B (zh) * 2019-09-02 2024-05-14 中国科学院上海应用物理研究所 一种x射线小角散射与x射线成像联用的光学系统
CN111863849B (zh) * 2020-07-29 2022-07-01 上海大学 一种x射线平板探测器及其制备方法

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