This application claims priority of Taiwan Application No. 107112576, filed on Apr. 12, 2018, the entirety of which is incorporated by reference herein.
The disclosure relates to an X-ray sensing device and a manufacturing method thereof, and in particular it relates to an X-ray sensing device having a columnar scintillator.
X-rays are widely used in the digital age. Example range from non-destructive detection in industrial applications to non-invasive imagery in the medical field. X-rays are frequently used in biomedical research, disease diagnosis, baggage inspection, and forensic science. X-rays are becoming more common in daily life and in technological applications, and have become an indispensable tool for modem technology.
X-ray sensing devices can detect X-rays and convert them into electronic signals to generate digital images. In general, X-ray sensing devices can be classified as indirect conversion type or direct conversion type. An indirect X-ray sensing device converts X-ray photons into visible light photons by using a scintillator formed of an X-ray conversion material, and converts visible light photons into electrons by photoelectric coupling elements. In addition, the electronic signals are converted into digital images by a thin-film transistor (TFT) or a complementary metal oxide semiconductor (CMOS) and related electronic components. The direct conversion type X-ray sensing device converts X-ray photons directly into electron-hole pairs by using a scintillator, and then converts the electronic signals into digital images by TFT or CMOS and related electronic components.
In the structure of a conventional X-ray sensing device, a bulk of a scintillator or a plate of a scintillator are mostly used. However, the manufacturing cost of the scintillator having large dimensions is high, and the crystal growth process for a scintillator having large dimensions is also more time consuming. On the other hand, in some X-ray sensing devices, an adhesive layer has to be used between the scintillator and the pixel array substrate (for example, it may include a photoelectric coupling element, TFT or CMOS). However, the adhesive layer may cause a decrease in image resolution or crosstalk interference in the signals.
In addition, whether the X-ray conversion material can be applied to a large-dimension process and whether sufficient conversion efficiency can be provided in the large-dimension process to reduce the dose of X-ray irradiation are also problems that should be taken into consideration in the conventional process.
Accordingly, further simplification of the process for manufacturing X-ray sensing devices and improving their performance are still topics that the industry is devoted to researching.
In accordance with some embodiments, the present disclosure provides an X-ray sensing device. The X-ray sensing device includes a substrate, a first material layer, a circuit element, a photoelectric sensing element and a columnar structure. The first material layer is disposed over the substrate. The circuit element is disposed at a bottom portion of the first material layer. The photoelectric sensing is element disposed over the circuit element. The columnar structure is correspondingly disposed over the photoelectric sensing element and is in contact with the photoelectric sensing element. The columnar structure includes a scintillator material. The X-ray sensing device further includes a pad disposed on a top surface or a bottom surface of the first material layer and is coupled to the circuit element.
In accordance with some embodiments, the present disclosure provides an X-ray sensing device. The X-ray sensing device includes a substrate, a first material layer, a circuit element and a columnar structure. The first material layer is disposed over the substrate. The circuit element is disposed at a bottom portion of the first material layer. The columnar structure is disposed over the circuit element and is in contact with the circuit element. The columnar structure includes a scintillator material. The X-ray sensing device further includes a pad disposed on a top surface or a bottom surface of the first material layer and is coupled to the circuit element.
In accordance with some embodiments, the present disclosure provides a method for manufacturing an X-ray sensing device. The method includes providing a carrier substrate, forming a first material layer over the substrate, patterning the first material layer to form an opening that exposes a portion of the surface of the photoelectric sensing element, and filling a scintillator material in the opening to form a columnar structure. A circuit element is disposed at a bottom portion of the first material layer, and a photoelectric sensing element is disposed over the circuit element. In addition, the columnar structure is in contact with the photoelectric sensing element.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The disclosure may be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The X-ray sensing device of the present disclosure and the manufacturing method thereof are described in detail in the following description. In the following detailed description, for purposes of explanation, numerous specific details and embodiments are set forth in order to provide a thorough understanding of the present disclosure. The specific elements and configurations described in the following detailed description are set forth in order to clearly describe the present disclosure. It will be apparent, however, that the exemplary embodiments set forth herein are used merely for the purpose of illustration, and the inventive concept may be embodied in various forms without being limited to those exemplary embodiments. In addition, the drawings of different embodiments may use like and/or corresponding numerals to denote like and/or corresponding elements in order to clearly describe the present disclosure. However, the use of like and/or corresponding numerals in the drawings of different embodiments does not suggest any correlation between different embodiments. In addition, in this specification, expressions such as “a first material layer disposed on/over a second material layer”, may indicate the direct contact of the first material layer and the second material layer, or it may indicate a non-contact state with one or more intermediate layers between the first material layer and the second material layer. In the above situation, the first material layer may not be in direct contact with the second material layer.
In addition, in this specification, relative expressions are used. For example, “lower”, “bottom”, “higher” or “top” are used to describe the position of one element relative to another. It should be appreciated that if a device is flipped upside down, an element that is “lower” will become an element that is “higher”.
It should be understood that, although the terms “first”, “second”, “third” etc. may be used herein to describe various elements, components, regions, layers, portions and/or sections, these elements, components, regions, layers, portions and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, portion or section from another region, layer or section. Thus, a first element, component, region, layer, portion or section discussed below could be termed a second element, component, region, layer, portion or section without departing from the teachings of the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should be appreciated that, in each case, the term, which is defined in a commonly used dictionary, should be interpreted as having a meaning that conforms to the relative skills of the present disclosure and the background or the context of the present disclosure, and should not be interpreted in an idealized or overly formal manner unless so defined.
It should be understood that this description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. The drawings are not drawn to scale. In addition, structures and devices are shown schematically in order to simplify the drawing.
In accordance with some embodiments of the present disclosure, the X-ray sensing device is provided. The X-ray sensing device has the columnar structure containing the scintillator materials. The columnar structure is correspondingly disposed over the photoelectric sensing element and is in direct contact with the photoelectric sensing element or the circuit element. In such a configuration, the amount of scintillator materials can be saved, and the detective quantum efficiency (DQE) and resolution of imaging of the X-ray sensing devices can be improved. In addition, in accordance with some embodiments of the present disclosure, the X-ray sensing device is fabricated by simple semiconductor processes, and the fabricated columnar structure can be accurately aligned with the photoelectric sensing element or the circuit element. Accordingly, the process efficiency and product yield can be improved.
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In addition, in accordance with some embodiments, a thinning process may be performed on the first material layer 102 that is formed on the carrier substrate 108. The first material layer 102 may be thinned to an appropriate thickness so that the subsequent processes (e.g., the patterning process) may be carried out successfully. In some embodiments, the thinned first material layer 102 has a first height H1 ranging from about 50 μm to about 700 μm.
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Moreover, the columnar structure 114 has a second height H2. In some embodiments, the second height H2 of the columnar structure 114 is in a range from about 50 μm to about 700 μm. In addition, the top portion of the columnar structure 114 has a first width W1 and the bottom portion of the columnar structure 114 has a second width W2. In some embodiments, the first width W1 of the columnar structure 114 is different from the second width W2 of the columnar structure 114. In some embodiments, the first width W1 is greater than the second width W2. In addition, the aspect ratio of the columnar structure 114 is in a range from about 1:1 to about 2:1 in accordance with some embodiments.
In some embodiments, the aspect ratio of the columnar structure 114 can be defined as the ratio of the second height H2 of the columnar structure 114 to the first width W1 of the top portion of the columnar structure 114, i.e. H2/W1. In other embodiments, the aspect ratio of the columnar structure 114 can be defined as the ratio of the second height H2 of the columnar structure 114 to the second width W2 of the bottom portion of the columnar structure 114, i.e. H2/W2. In other embodiments, the aspect ratio of the columnar structure 114 can be defined as the ratio of the second height H2 of the columnar structure 114 to any width W3 of the columnar structure 114, i.e. H2/W3. It should be noted that an appropriate range of the aspect ratio allows the columnar structure 114 to efficiently transmit visible light photons or electrons.
On the other hand, the photoelectric sensing element 104 has a fourth width W4. The fourth width W4 of the photoelectric sensing element 104 is greater than the second width W2 of the columnar structure 114. In some embodiments, the fourth width W4 of the photoelectric sensing element 104 is in a range from about 1 um to about 200 um.
As described above, the X-ray sensing device 10 as shown in
Furthermore, a second material layer (not illustrated) may be formed over the top surface 102a of the first material layer 102 in accordance with some embodiments. The second material layer may cover the first material layer 102 and be in contact with the first material layer 102 and the scintillating material 112. The second material layer may be used to further reduce crosstalk interference of the adjacent sensing elements or pixels. In some embodiments, the material of the second material layer may include tantalum oxides (TaO2), copper (Cu), aluminum (Al) or a combination thereof.
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As described above, the X-ray sensing device 20 as shown in
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Next, a conductive layer 118 is formed over the dielectric layer 116. The conductive layer 118 may be formed of conductive materials. In some embodiments, the conductive material may include copper (Cu), aluminum (Al), molybdenum (Mo), tungsten (W), gold (Au), chromium (Cr), nickel (Ni), platinum (Pt), titanium (Ti), iridium (Ir), rhodium (Rh), copper alloys, aluminum alloys, molybdenum alloys, tungsten alloys, gold alloys, chromium alloys, nickel alloys, platinum alloys, titanium alloys, iridium alloys, rhodium alloys, any other applicable conductive material, or a combination thereof. In some embodiments, the conductive layer 118 may be formed by a chemical vapor deposition (CVD) process, a physical vapor deposition (PVD) process, an electroplating process, an electroless plating process, any other applicable process, or a combination thereof. The physical vapor deposition process may include a sputtering process, an evaporation process, or a pulsed laser deposition (PLD) process.
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In this embodiment, since the columnar structure 114 has the conductive layer 118, the columnar structure 114 may also serve as a via to provide additional electrical connection to the columnar structure 114. In addition, the conductive layer 118 is also disposed aligned with the photoelectric sensing element 104, and has anti-scattering effect to prevent scattered X-rays from entering the X-ray sensing device. Therefore, the quality of the generated image may be further improved.
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Moreover, the pad 120 may be further coupled to an external circuit (not illustrated) through a solder ball 122 to electrically connect the X-ray sensing device 30 to the external circuit. The solder ball 122 is disposed below the circuit element 106, and is coupled to the circuit element 106 through the pad 120 disposed on the bottom surface 102b of the first material layer 102. The solder ball 122 may be formed of any suitable material. In some embodiments, the solder ball 122 may include tin (Sn), silver (Ag), copper (Cu), any other applicable material, or a combination thereof.
Furthermore, the solder ball 122 may be disposed over the substrate 108′ for the subsequent packaging processes of X-ray sensing device 30 in accordance with some embodiments. In some embodiments, the substrate 108′ may be a silicon substrate, a glass substrate, a polymer substrate, a polymer-based composite substrate, or a combination thereof, but it is not limited thereto. In some embodiments, the material of the substrate 108′ may include glass, quartz, sapphire, polycarbonate (PC), polyimide (PI), polyethylene terephthalate (PET), any other applicable material, or a combination thereof.
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In addition, it should be understood that although the X-ray sensing devices shown in
To summarize the above, the X-ray sensing device provided in the embodiments of the present disclosure includes the columnar structure containing the scintillator materials. In such a configuration, the amount of scintillator materials can be saved, and the detective quantum efficiency and resolution of imaging of the X-ray sensing devices can be improved. In addition, in accordance with some embodiments of the present disclosure, the X-ray sensing device is fabricated by simple semiconductor processes, and the fabricated columnar structure can be accurately aligned with the photoelectric sensing element or the circuit element. Accordingly, the process efficiency and product yield can be improved.
Furthermore, in accordance with some embodiments of the present disclosure, there is no need to use an adhesive layer to fix the elements (for example, the adhesive layer is not required to fix the photoelectric sensing element with the circuit element, or the adhesive layer is not required to fix the photoelectric sensing element with the columnar structure and so on). Therefore, the crosstalk interference of the signals may be reduced.
Although some embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, it will be readily understood by one of ordinary skill in the art that many of the features, functions, processes, and materials described herein may be varied while remaining within the scope of the present disclosure. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Number | Date | Country | Kind |
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107112576 | Apr 2018 | TW | national |