Patent Description:
In medical or industrial radiography, a digital X-ray detector has been widely used. Such a digital X-ray detector may be commonly referred to as an X-ray detector or an image detector. Further, such a digital detector may be classified into an indirect conversion type X-ray detector and a direct conversion type X-ray detector. The indirect conversion type X-ray detector i) converts X-rays (e.g., X-ray photons) into visible light (e.g., light photons) using a scintillator and ii) converts the visible light into an electric signal. The direct conversion digital detector directly converts X-rays into an electric signal using a photoconductive layer.

As described, an X-ray detector detects X-ray signals that are radiated from an X-ray source, have passed through a target object, and reached to the X-ray detector. The X-ray detector converts the detected X-ray signals into electric signals. Such an X-ray detector includes a pixel array panel including a plurality of pixels. Each pixel includes a light receiving element (e.g., photoconductor or photodiode) and a driving element for driving the light receiving element of each pixel.

Such an X-ray detector (e.g., photodiode) may be manufactured using a thin-film transistor (TFT) process or a complementary metal-oxide-semiconductor (CMOS) process. The TFT process is advantageous for manufacturing a large surface X-ray detector with a low manufacture unit price. The CMOS process is advantageous for manufacturing a high image quality X-ray detector generating comparably low radiation dose and having a dynamic imaging capability. However, the TFT process may have limitations for manufacturing a high image quality X-ray detector because it is difficult to form metal lines in a nanometer level due to a high temperature chamber and an amorphous process. The CMOS process may have limitations for manufacturing a large surface X-ray detector because of a silicon wafer size.

Therefore, there is a demand for a mass production method for manufacturing a large surface X-ray detector having a high image quality and generating a comparably low radiation dose.

<CIT> discloses a 3D high resolution indirect X-ray sensor which includes a silicon wafer that includes an array of photodiodes thereon with each of the photodiodes having a contact on a front side of the silicon wafer and self-aligned with a respective grid hole of an array of grid holes that are on a back side of the silicon wafer. Each of the grid holes is filled with a scintillator configured to convert beams of X-ray into light. The indirect X-ray sensor also includes one or more silicon dies with an array of photo-sensing circuits each of which including a contact at a top surface of the one or more silicon dies. Contact on each of the photodiodes is aligned and bonded to contact of a respective photo-sensing circuit of the array of photo-sensing circuits of the one or more silicon dies.

Moreover, reference is made to <CIT> and <CIT> as relevant prior art.

In accordance with the present invention, an X-ray detector with the features of claim <NUM> may include a plurality of pixel driving micro integrated chips (ICs) printed on a top of a photodiode layer, using a micro-transfer printing technology.

The X-ray detector may further include a plurality of pixel driving micro integrated chips on photodiodes, each to form a three dimensional structure with an inter-layer dielectric (ILD) metal contact and a bottom photodiode layer in order to maximize a fill factor (e.g., an area ratio of a photodiode area in a unit pixel), to improve an absorption ratio of X-ray (e.g., X-ray photons), and to minimize an X-ray exposure dose.

The X-ray detector may further be a back side illumination (BSI) type detector and include a pixel driving micro IC printed on a top of a photodiode layer, using a micro-transfer printing technology.

The X-ray detector may further include a plurality of pixel driving micro ICs which is formed on a source silicon wafer, transferred onto a stamp, and printed on a photodiode layer as a target panel through the stamp.

The X-ray detector may further include i) a photodiode layer fabricated through a thin film transistor (TFT) process and ii) a plurality of pixel driving micro ICs fabricated separately from the photodiode layer, fabricated on a source silicon wafer through a complementary metal oxide semiconductor (CMOS) process, and printed on the photodiode layer.

The X-ray detector may further have a photodiode layer including i) a plurality of photodiodes formed as a continuous layer in order to minimize a unit manufacture price or ii) a plurality of photodiodes formed in an Island array structure in order to minimize the crosstalk of electric signals generated from adjacent pixels.

The X-ray detector may further have a comparatively light weight and an improved durability by removing a passivation layer (e.g., glass substrate) of a panel substrate using a laser lift off technique.

The X-ray detector may further be provided for including a photodiode layer including a plurality of photodiodes and configured to receive X-ray (e.g., X-ray photons) that have passed through a target object and convert the received X-ray (e.g., X-ray photons) to electric signals, and a driver layer formed on the photodiode layer and including a plurality of micro driving integrated chips each coupled to two or more photodiodes in the photodiode layer. The plurality of pixel driving integrated chips may be manufactured separately from the photodiode layer and printed on the photodiode layer using a micro-transfer printing method.

Each one of the plurality of pixel driving integrated chips may be coupled to two or more photodiodes in the photodiode layer and controls the coupled photodiodes, especially to four photodiodes.

Each one of the plurality of pixel driving integrated chips may include a timing generator configured to generate a timing signal to sequentially control the coupled photodiodes, a plurality of switches each coupled to corresponding photodiode, and a pixel driver transistor configured to sequentially turn on the plurality of switches according to the generated timing signal.

The photodiode layer may be manufactured using a thin-film transistor (TFT) process. The plurality of pixel driving integrated chips may be manufactured on a source wafer using a complementary metal-oxide-semiconductor (CMOS) process, transferred onto an elastomer stamp, and printed on the photodiode layer using the elastomer stamp through the micro-transfer printing method.

The X-ray detector may further include a scintillator layer formed on the driver layer as a front side illumination type X-ray detector and configured to convert X-ray photons to visible light photons.

The X-ray detector may further include a scintillator layer formed on the photodiode layer as a back side illumination type X-ray detector and configured to convert X-ray photons to visible light photons.

Each one of the plurality of pixel driving integrated chips may be formed on the photodiode layer to form a three-dimension structure with corresponding metal contacts and a corresponding common bottom layer of a corresponding photodiode.

An adhesive layer made of predetermined resin may be formed on the photodiode layer for printing the plurality of micro driving integrated chips thereon.

The plurality of micro driving integrated chips may be fabricated on a source silicon wafer, the plurality of fabricated micro driving integrated chips may be transferred onto an elastomer stamp, and the plurality of fabricated micro driving integrated chips may be printed on the photodiode layer by stamping the elastomer stamp on the photodiode layer.

The printing operation may include fabricating the plurality of micro driving integrated chips on a source silicon wafer, transferring the plurality of fabricated micro driving integrated chips onto an elastomer stamp, and printing the plurality of fabricated micro driving integrated chips on the photodiode layer by stamping the elastomer stamp on the photodiode layer.

The fabricating of the plurality of micro driving integrated chips may include performing a complementary metal oxide semiconductor (CMOS) process to fabricate the plurality of micro driving integrated chips on the source wafer, and the forming of the photodiode layer may include performing a thin-film transistor (TFT) process to fabricate the photodiode layer.

The manufacturing of the X-ray detector may further include forming an adhesive layer on the photodiode layer for printing the plurality of micro driving integrated chips on the photodiode layer, wherein the plurality of micro driving integrated chips is transferred onto an elastomer stamp, and the plurality of transferred micro driving integrated chips on the elastomer stamp is printed on the photodiode layer.

The forming of the metal contact layers may include forming the metal contact layers for coupling each one of the plurality of micro driving integrated chips to corresponding four adjacent photodiodes in the photodiode layer, wherein the each one micro driving integrated chip is configured to sequentially or simultaneously control the coupled four adjacent photodiodes.

The manufacturing of the X-ray detector may further include forming a scintillator layer formed on the driver layer as a front side illumination type X-ray detector.

The manufacturing of the X-ray detector may further include removing the insulating substrate, for example, glass substrate of the photodiode layer using a laser lift off technique, flipping the driver layer and the photodiode layer and placed the flipped resultant on an adhesive layer formed on a carrier substrate, and forming a scintillator layer formed on a bottom common electrode layer of the photodiode layer as a back side illumination type X-ray detector.

In the printing a plurality of micro driving integrated chips on the photodiode layer, each one of the plurality of pixel driving integrated chips may be placed to form a three dimensional structure with corresponding metal contacts and a corresponding common bottom layer of a corresponding photodiode.

In accordance with at least one embodiment, an X-ray detector may be provided to have a comparatively simple structure that allows to be manufactured in a mass production method while providing a high image quality. In particular, the X-ray detector may include i) a photodiode layer including a plurality of pixels in a form of matrix which is fabricated independently from other elements, such as pixel driving micro integrated chips, and ii) a plurality of pixel driving micro integrated chips (ICs) that is fabricated separately from the photodiode layer and printed on a top of the photodiode layer, using a micro-transfer printing technology, and each pixel driving micro integrated chip may be coupled to multiple pixels (e.g., photodiodes) to simultaneously and sequentially control the coupled multiple pixels. The photodiode layer may be fabricated using a thin-film transistor (TFT) process which is advantageous in manufacturing a large surface detector at a low unit manufacturing price, and the pixel driving micro integrated chip may be fabricated using a complementary metal-oxide-semiconductor (CMOS) process which is advantages in manufacturing a detector with high precision and high quality. In particular, the pixel driving micro integrated chips may be formed on a source silicon wafer, transferred on an elastomer stamp, and printed on the photodiode layer using the elastomer stamp. Accordingly, the X-ray detector according to an embodiment may be manufactured through a mass production method while maintaining the high image quality. Furthermore, since one pixel driving micro integrated chip controls multiple pixels, the X-ray detector may require comparatively less metal lines (e.g., data lines and gate lines) and fewer fabricating steps.

In accordance with at least one embodiment, the X-ray detector may be a front side illumination type detector. In this case, i) a photodiode layer including a plurality of photodiodes may be fabricated, ii) the plurality of pixel driving micro integrated chips may be printed on the photodiode layer, and iii) a scintillator layer may be formed on the top of the plurality of pixel driving micro integrated chips printed on the photodiode layer. Each pixel driving micro integrated chip does not block a corresponding pixel. Instead, each pixel droving micro integrated chip may form a three-dimensional structure with an inter-layer dielectric (ILD) metal contacts and a bottom photodiode layer. Accordingly, a fill factor of the front-side illumination type X-ray detector may be maximized while requiring comparatively fewer manufacturing steps. Due to such a maximized fill factor, the X-ray detector may have a comparatively high absorption ratio of X-ray photons, thereby minimizing an X-ray exposure dose to a target object (e.g., patient).

In accordance with another embodiment, the X-ray detector may be a back side illumination type detector. In this case, i) a photodiode layer including a plurality of pixels (e.g., photodiodes) may be fabricated on a insulating substrate, for example, glass substrate, ii) the plurality of pixel driving micro integrated chips may be printed on the photodiode layer, iii) the insulating substrate, for example, glass substrate may be removed by a laser lift off technique, iv) the resultant may be flipped and placed on a carrier substrate, and v) a scintillator layer may be formed on the top of the bottom electrode layer. Accordingly, photodiodes in the photodiode layer may receive light protons from the scintillator layer without being blocked by the pixel driving micro IC and metal contacts thereof.

In accordance with yet another embodiment, an X-ray detector may include a photodiode layer (e.g., photodiode layer) that is formed as a continuous layer. Such a structure may allow minimizing a unit manufacturing price.

In accordance with further another embodiment, an X-ray detector may include a photodiode layer includes a plurality of photodiodes in a form of an island array structure. Such a structure of the X-ray detector may minimize the crosstalk of electric signals generated between pixels.

In accordance with still another embodiment, an X-ray detector may have a comparatively light weight by removing a glass layer (e.g., a passivation layer of a panel substrate) using a laser lift off technique. Since the X-ray detector includes no insulating substrate, for example, glass substrate, the X-ray detector may have enhanced durability.

Hereinafter, the X-ray detector and the method for manufacturing the same according to embodiments will be described with reference to the accompanying drawings. For convenience of describing and ease of understanding, an X-ray detector may be representatively denote a detector receiving X-ray (e.g., X-ray photons) passed through a target object and generating electric signals by converting the received X-ray photons. However, the embodiments of the present disclosure are not limited thereto. The X-ray detector may be referred as an imaging detector, an image sensor, a digital detector, and so forth.

<FIG> is a view illustrating an X-ray detector receiving X-ray (e.g., X-ray photons) transmitted form an X-ray source and passed through a target object in accordance with at least one embodiment.

Referring to <FIG>, X-ray detector <NUM> and X-ray source <NUM> may be respectively installed and disposed to face each other. X-ray source <NUM> may generate X-ray (e.g., X-ray photons) and radiate the generated X-ray toward target object <NUM>, such as a patient.

X-ray detector <NUM> may i) receive X-ray (e.g., X-ray photons) that are generated from X-ray source <NUM> and passed through target object <NUM> and ii) convert the received X-ray (e.g., X-ray photons) indirectly or directly to electric signals in accordance with at least one embodiment. X-ray detector <NUM> may have a rectangular shape in plan, but the shape of X-ray detector <NUM> is not limited to thereto.

In accordance with at least one embodiment, X-ray detector <NUM> may be an indirect type X-ray detector that receives X-ray (e.g., X-ray photons) passed through target object <NUM>, converts the X-ray (e.g., X-ray photons) to visible light photons, and converts the visible light photons into the electric signals. Accordingly, X-ray detector <NUM> may include a scintillator layer for converting X-rays photons into visible light photons. Such a scintillator layer may be made of cesium iodide (CsI), but the embodiments of the present disclosure are not limited thereto. For example, X-ray detector <NUM> may be a direct type X-ray detector that converts the X-ray (e.g., X-ray photons) directly to electrical signals. In case of the direct type X-ray detector, X-ray detector <NUM> may exclude the scintillator layer.

In accordance with at least one embodiment, X-ray detector <NUM> may include a plurality of pixel driving micro integrated chips (ICs) that are separately fabricated from a photodiode layer by using a manufacturing method allowing high precision fabrication different from that for manufacturing a photodiode layer and are printed on a top of a photodiode layer, using a micro-transfer printing technology. Therefore, such a structure of X-ray detector <NUM> may allow to be manufactured in mass production while maintaining high image quality and generating comparatively less X-ray does in accordance with at least one embodiment.

In X-ray detector <NUM>, each pixel driving micro IC may form a three dimensional structure with an inter-layer dielectric (ILD) metal contact and a bottom photodiode layer in accordance with at least one embodiment. Such a structure of X-ray detector <NUM> may maximize a fill factor, improve an absorption ratio of X-ray photons, and minimize an X-ray exposure dose of target object <NUM>. Herein, the fill factor denotes an area ratio of a photodiode area in a unit pixel.

In accordance with another embodiment, X-ray detector <NUM> may be a back side illumination (BSI) type. In case of the back side illumination type X-ray detector, a driver layer including pixel driving micro integrated chips is placed beneath a photodiode layer, and a scintillator layer is formed above a bottom electrode of the photodiode layer. Accordingly, the pixel driving micro integrated chips and metal contact layers do not block light photons to reach the photodiode layer. Such a structure of back side illumination type X-ray detector <NUM> further improves the fill factor in accordance with another embodiment of the present disclosure.

In accordance with at least one embodiment, X-ray detector <NUM> may include i) photodiode layer (e.g., photodiode layer) that is made of amorphous silicon (a-Si) or organic photodiode and formed as a continuous layer or arranged in an island array structure. In case of forming in a continuous layer, it may minimize a unit manufacture price. In case of forming in the island array structure, it may minimize crosstalk of electric signals generated between pixels.

In accordance with at least one embodiment, X-ray detector <NUM> may have a comparatively light weight and enhanced durability by removing a passivation layer and a insulating substrate, for example, glass substrate using a laser lift off technique.

Hereinafter, such a structure of X-ray detector <NUM> will be described in more detail with reference to <FIG> illustrates an internal structure of an X-ray detector in accordance with at least one embodiment.

Referring to <FIG>, X-ray detector <NUM> may include pixel area circuit <NUM>, gate driver circuit <NUM>, data driver circuit <NUM>, and control circuit <NUM> in accordance with at least one embodiment. Pixel area circuit <NUM> may be a main panel that receives X-ray photons, converts X-ray (e.g., X-ray photons) to visible light photons, and converts light photons to electric signals. That is, pixel area circuit <NUM> may be an indirect conversion type in accordance with at least one embodiment. However, the embodiments of the present disclosure are not limited thereto. For example, pixel area circuit <NUM> in another embodiment may be a direct conversion type. In the direct conversion type, pixel area circuit <NUM> excludes a scintillator layer and converts X-ray (e.g., X-ray photons) directly to electric signals.

Pixel area circuit <NUM> may include a plurality of pixels P, each serving as a unit photo-electric conversion element, arranged in matrix in accordance with at least one embodiment. Each pixel P may be a unit of a light receiving element (e.g., light conversion element). Each pixel P may include a photodiode that converts the incident light into the electrical signals. Each pixel P may be coupled to gate driver circuit <NUM> through gate lines GL formed to extend in a row direction and to data driver circuit <NUM> through data lines DL formed to extend in a column direction.

Typically, each pixel P includes a pixel driving element for controlling a corresponding pixel to read a signal accumulated therein. Unlike the typical art, pixel P does not include a pixel driving element in accordance with at least one embodiment. In accordance with at least one embodiment, pixel area circuit <NUM> may include a plurality of pixel driving micro integrated chips (ICs) that are separated fabricated from a photodiode layer and printed on the photodiode layer using a micro-transfer printing technology. The micro-transfer printing technology may use an elastomer stamp to print devices (e.g., pixel driving micro integrated chips) on a target panel (e.g., a photodiode layer).

In particular, the plurality of micro driving integrated chips may be fabricated on a source silicon wafer, for example, using a CMOS process, the plurality of fabricated micro driving integrated chips may be transferred onto an elastomer stamp, and the plurality of fabricated micro driving integrated chips may be printed on the photodiode layer by stamping the elastomer stamp on the photodiode layer.

Each of the pixel driving micro integrated chips <NUM> may be coupled to four photodiodes and sequentially control the four pixels in accordance with at least one embodiment. However, the embodiments of the present disclosure are not limited thereto. For example, one pixel driving micro integrated chip <NUM> may be coupled to two photodiodes, three photodiodes, or five photodiodes in accordance with another embodiment. That is, one pixel driving micro integrated chip <NUM> may be coupled to more than two photodiodes. The number of photodiodes coupled to one pixel driving micro integrated chip may depend on various factors influencing manufacturing efficiency or performance properties, such as a circuit design.

Each of pixel driving micro integrated chips <NUM> may switch on coupled four photodiodes, sequentially, in response to a signal from gate driver circuit <NUM>, read data from the coupled four photodiodes, and output the read data to data driver circuit <NUM>. Such a pixel driving micro integrated chip <NUM> will be described with reference to <FIG> in more detail.

Referring to <FIG> again, X-ray detector <NUM> may include gate drive circuit <NUM>, data drive circuit <NUM>, and control circuit <NUM>. Control circuit <NUM> may generate control signal, transmit the generated control signal to gate driver circuit <NUM> and data driver circuit <NUM>, and controls the operation of gate drive circuit <NUM> and data drive circuit <NUM>. Control circuit <NUM> receives the read out data D from data drive circuit <NUM> and may deliver the data D on a per-frame basis to an image processing circuit (not shown) outside X-ray detector <NUM>.

Gate driver circuit <NUM> may control the timing of output of a gate signal according to the gate control signal supplied from control circuit <NUM>. Data driver circuit <NUM> read outs the data accumulated in the pixels P. The read out data D are delivered to the control circuit <NUM>. The data drive circuit <NUM> is controlled based on the data control signal supplied from the control circuit <NUM>.

As described, X-ray detector <NUM> includes a plurality of pixel driving micro integrated chips <NUM>, each coupled to four photodiodes and controlling the coupled four photodiodes, sequentially. Such a pixel driving micro integrated chip <NUM> will be described with reference to <FIG> in more detail.

<FIG> is a circuit diagram illustrating a pixel driving micro integrated chip in accordance with at least one embodiment. Referring to <FIG>, pixel driving micro integrated chip <NUM> may be coupled to first photodiode PD1, second photodiode PD2, third photodiode PD3, and four photodiode PD4 and sequentially control four photodiodes PD1, PD2, PD3, and PD4. In particular, pixel driving micro integrated chip <NUM> may sequentially turn on corresponding switches of first to four photodiode PD1 to PD4, sequentially read data accumulated in first to four photodiodes PD1 to PD4, and sequentially output read data to data driver circuit <NUM>, in accordance with at least one embodiment.

In order to sequentially control the photodiodes, pixel driving micro integrated chip <NUM> may include timing generator <NUM>, pixel driver transistor (TR) <NUM>, and four switches <NUM> to <NUM>. For example, pixel driving micro integrated chip <NUM> may be electrically coupled to first photodiode PD1 through first switch <NUM>, electrically coupled to second photodiode PD2 through second switch <NUM>, electrically coupled to third photodiode PD3 through third switch <NUM>, and electrically coupled to fourth photodiode PD4 through fourth switch <NUM>.

Timing generator <NUM> may receive a clock signal (CLK), for example, from gate driver circuit <NUM> and generate a timing signal to sequentially switch first to fourth switches <NUM> to <NUM>. In accordance with at least one embodiment, timing generator <NUM> may be implemented with a digital counter or a shift register. In particular, a <NUM>-bit counter may be used to minimize an IC size.

Pixel driver transistor (TR) <NUM> may read data from one of photodiodes PD1to PD4 which is switched on by the timing signal from timing generator <NUM> and output the data to data driver circuit <NUM>. Such pixel driver transistor (TR) <NUM> may be implemented in a three transistor (3T) structure or a four transistor (4T) structure.

As described, four photodiodes are controlled by one pixel driver micro IC <NUM> in accordance with at least on embodiment. Such a structure of X-ray detector <NUM> minimizes metal lines coupled to pixels and driver circuits. Accordingly, the above-described structure improves a fill factor, simplifies a manufacturing process, and reduces a unit manufacturing price in accordance with at least one embodiment.

<FIG> is a cross sectional view of a predetermined section in a pixel area of an X-ray detector in accordance with one embodiment of the present disclosure.

For example, <FIG> shows a predetermined part of a pixel area of a front side illumination type X-ray detector according to one embodiment. As shown in <FIG>, the pixel area of the X-ray detector may include three major layers, photodiode layer <NUM>, driver layer <NUM>, and scintillator layer <NUM>.

In accordance with at least one embodiment, photodiode layer <NUM> may include common electrode <NUM> formed on insulating substrate <NUM>, a plurality of photodiodes <NUM> arranged on common electrode <NUM> in matrix, and top transparent pixel electrode <NUM>. For example, insulating substrate <NUM> may be a glass substrate.

A plurality of photodiodes <NUM> may receive visible light photons and convert light photons into an electrical signal. Such photodiode <NUM> may have a PIN diode structure including a P+ type region (e.g., high-concentration P type), a I type region, and an N type region. For example, the P type photoconductive material may be CdTe.

Such photodiode layer <NUM> may be manufactured using a TFT process in accordance with at least one embodiment. Accordingly, photodiode layer <NUM> may be manufactured as a large surface X-ray detector with a comparatively low manufacturing price. Furthermore, such photodiode layer <NUM> may be manufactured as a continuous layer for a comparatively low manufacturing price. Alternatively, photodiode layer <NUM> may be formed in an island array structure by patterning the continuous photodiode layer. In this case, such a structure may minimize crosstalk between adjacent photodiodes.

Driver layer <NUM> may include a plurality of pixel driving ICs <NUM> each controlling at least two of photodiodes and metal contacts connecting pixel driving ICs to corresponding photodiodes <NUM>. In an embodiment of the present disclosure, one pixel driving IC <NUM> sequentially or simultaneously controls four photodiodes. However, the embodiments of the present disclosure are not limited thereto. The number of photodiodes controlled by one pixel driving IC <NUM> may be vary according to various factors related to the X-ray detector.

In particular, a plurality of pixel driving ICs <NUM> are manufactured separately from the photodiode layer <NUM> and printed on photodiode layer <NUM> using the micro-transfer printing technology after forming contact holes in photodiode layer <NUM>. Then, metal contacts <NUM> are formed to connect pixel driving ICs <NUM> to corresponding photodiodes <NUM>. As described, the plurality of pixel driving ICs <NUM> may be manufactured using a CMOS process and printed on photodiode layer <NUM> using the micro-transfer technology. Accordingly, pixel driving ICs <NUM> may be manufactured with high precision (e.g., nanometer level) to have a high image quality.

Scintillator layer <NUM> may be formed on driver layer <NUM>. Scintillator layer <NUM> may convert X-rays into visible light. Scintillator layer <NUM> may have flexible properties. Scintillator layer <NUM> may be formed of CsI or Gadox (Gd2O2:Tb).

<FIG> is a cross sectional view of a predetermined section in a pixel area of an X-ray detector in accordance with another embodiment of the present disclosure. For example, <FIG> shows a predetermined part of a pixel area of a back side (BS) illumination type X-ray detector according to one embodiment. As shown in <FIG>, the pixel area of the X-ray detector may include driver layer <NUM>-<NUM>, photodiode layer <NUM>-<NUM>, and scintillator layer <NUM>-<NUM>. Each of driver layer <NUM>-<NUM>, photodiode layer <NUM>-<NUM>,and scintillator layer <NUM>-<NUM> of the BS illumination type X-ray detector may have a structure similar to corresponding layers of the FS illumination type X-ray detector.

As shown in <FIG>, photodiode layer <NUM>-<NUM> may be presented on driver layer <NUM>-<NUM> in the BS illumination type X-ray detector. That is, driver layer <NUM>-<NUM> and photodiode layer <NUM>-<NUM> of <FIG> may be upside down photodiode layer <NUM> and driver layer <NUM> of <FIG>. For example, driver layer <NUM>-<NUM> is formed on photodiode layer <NUM>-<NUM>, and the resultant of driver layer <NUM>-<NUM> and photodiode layer <NUM>-<NUM> is flipped in accordance with at least one embodiment. Then, the resultant may be placed on adhesive layer <NUM> on carrier substrate <NUM>. Accordingly, in the BS illumination type X-ray detector, the common electrode of photodiode layer <NUM>-<NUM> is the upper most layer of photodiode layer <NUM>-<NUM>, and pixel driver micro IC <NUM> is presented in the bottom most layer.

As shown in <FIG>, metal contact lines and pixel driver micro IC do not block photodiodes <NUM> in accordance with at least one embodiment. Accordingly, the BS illustration type X-ray detector may deliver light photons to photodiode <NUM> without loss.

Furthermore, before flipping the resultant of driver layer <NUM>-<NUM> and photodiode layer <NUM>-<NUM>, insulating substrate <NUM> may be removed using a laser lift off technology, and barrier layer <NUM> and scintillator layer <NUM> are formed on photodiode layer <NUM>-<NUM> using material having flexible property. Accordingly, the durability and the flexibility of X-ray detector may be improved.

Similar to the FS illumination type X-ray detector, photodiode layer <NUM>-<NUM> may be manufactured using a TFT process in accordance with at least one embodiment. Accordingly, photodiode layer <NUM>-<NUM> may be manufactured as a large surface X-ray detector with a comparatively low manufacturing price. Furthermore, such photodiode layer <NUM>-<NUM> may be manufactured as a continuous layer for a comparatively low manufacturing price. Alternatively, photodiode layer <NUM>-<NUM> may be formed in an island array structure by patterning the continuous photodiode layer. In this case, such a structure may minimize crosstalk between adjacent photodiodes.

Similar to the FS illumination type X-ray detector, driver layer <NUM>-<NUM> may include a plurality of pixel driving ICs <NUM> each controlling at least two of photodiodes and metal contacts connecting pixel driving ICs to corresponding photodiodes <NUM>. In an embodiment of the present disclosure, one pixel driving IC <NUM> sequentially or simultaneously controls four photodiodes. However, the embodiments of the present disclosure are not limited thereto. The number of photodiodes controlled by one pixel driving IC <NUM> may be vary according to various factors related to the X-ray detector.

Similar to the FS illumination type X-ray detector, photodiode layer <NUM>-<NUM> may include common electrode <NUM> formed on insulating substrate <NUM>, a plurality of photodiodes <NUM> arranged on common electrode <NUM> in matrix, and top transparent pixel electrode <NUM>. A plurality of photodiodes <NUM> may receive visible light photons and convert light photons into an electrical signal. Such photodiode <NUM> may have a PIN diode structure including a P+ type region (e.g., high-concentration P type), a I type region, and an N type region. For example, the P type photoconductive material may be CdTe.

Unlike the FS illumination type X-ray detector, scintillator layer <NUM>-<NUM> may be formed on photodiode layer <NUM>-<NUM>. Such scintillator layer <NUM>-<NUM> may convert X-rays into visible light. Scintillator layer <NUM>-<NUM> may include scintillator <NUM> and barrier layer <NUM> and be made of material having flexible properties. Scintillator layer <NUM> may be formed of CsI or Gadox (Gd2O2:Tb).

Hereinafter, a method of manufacturing an X-ray detector according to the embodiments of the present disclosure will be described with reference to <FIG>.

<FIG> is a flowchart illustrating a method of manufacturing an X-ray detector according to at least one embodiment of the present disclosure. <FIG> are cross-sectional views for describing a method of manufacturing a front side illumination type X-ray detector in accordance with at least one embodiment. <FIG> are cross-sectional views for describing a method of manufacturing a back side illumination type X-ray detector in accordance with at least one embodiment.

Referring to <FIG>, photodiode layer <NUM> may be formed at step <NUM>. In particular, a plurality of photodiodes <NUM> may be formed on insulating substrate <NUM> at step S6010. In particular, <FIG> illustrates a process of forming a photodiode layer in accordance with at least one embodiment.

As illustrated in <FIG>, common bottom electrode <NUM> may be formed on insulating substrate <NUM>. Insulating substrate <NUM> may be made of material having flexible property. Common bottom electrode <NUM> may be made of indium tin oxide (ITO) or indium zinc oxide (IZO). Common bottom electrode <NUM> may be an ITO glass substrate or an IZO glass substrate, but the embodiments of the present disclosure are not limited thereto. In particular, common bottom electrode <NUM> may be a transparent layer for a back side illumination type X-ray detector. However, common bottom electrode <NUM> may be not a transparent layer for a front side illumination type X-ray detector. On common bottom electrode <NUM>, a plurality of photodiodes <NUM> are formed. Photodiodes <NUM> may be made of amorphous silicon (a-Si) or organic silicon. Photodiodes <NUM> may be formed by forming a i-Si layer on common bottom electrode <NUM>, forming a p-Si layer on the i-Si layer, and forming an n-Si layer on the p-Si layer.

Top transparent pixel electrode <NUM> may be formed on photodiodes <NUM>. Top transparent pixel electrode <NUM> may be made of indium tin oxide (ITO) or indium zinc oxide (IZO). Top transparent pixel electrode <NUM> may be an ITO glass substrate or an IZO glass substrate, but the embodiments of the present disclosure are not limited thereto. In particular, Top transparent pixel electrode <NUM> may be a transparent layer for a front side illumination type X-ray detector. However, Top transparent pixel electrode <NUM> may be not a transparent layer for a back side illumination type X-ray detector. As described, such photodiode layer <NUM> may be formed using the TFT process in accordance with at least one embodiment. Photodiode layer <NUM> may be formed as a continuous layer, thereby minimizing a unit manufacturing price. Furthermore, photodiode layer <NUM> may be formed in an Island array structure through patterning. That is, as shown, a plurality of photodiodes <NUM> is formed thereon in a form of matrix. In this case, the crosstalk between adjacent photodiodes may be minimized.

Referring back to <FIG>, driver layer <NUM> may be formed on photodiode layer <NUM> at steps S6020 to S6050. In particular, <FIG> are diagrams illustrating a procedure of forming a driving layer on a photodiode layer in accordance with at least one embodiment.

At step S6020, first inter layer dielectric (ILD) layer <NUM> (e.g., ILD1) may be formed on photodiode layer <NUM> to cover all photodiodes <NUM> and gaps between adjacent pixels, and a plurality of metal contact holes <NUM> may be formed in first ILD1 layer <NUM> as shown in <FIG>. In particular, one metal contact hole <NUM> may be formed on each photodiode to expose top transparent pixel electrode <NUM>.

At step S6030, first metal contact layer <NUM> may be formed to fill first contact hole <NUM> and to extend along the top surface of ILD1 layer <NUM> in predetermined length, as shown in <FIG>.

At step S6040, second ILD layer <NUM> (ILD2) may be formed on metal contact layer <NUM> and first ILD layer <NUM> (ILD1), and second contact holes <NUM> may be formed at each photodiode <NUM> in second ILD layer <NUM> (ILD2) to expose corresponding first metal contact layer <NUM>, as shown in <FIG>.

At step S6050, print adhesive layer <NUM> may be formed on second ILD layer <NUM> (ILD2) and second contact holes <NUM>, as shown in <FIG>. Print adhesive layer <NUM> may be made of resin and a thickness of about <NUM>.

Print adhesive layer <NUM> may be formed for printing pixel driving integrated chips (ICs) <NUM> thereon. That is, print adhesive layer <NUM> on photodiode layer <NUM> may be a target panel.

At step S6060, pixel driving integrated chips (ICs) <NUM> may be printed on print adhesive layer <NUM>. Each pixel driving IC may be positioned between two adjacent pixels, as shown in <FIG>. In particular, each pixel driving IC may be position to sequentially control corresponding four photodiodes in accordance with at least one embodiment.

Hereinafter, a micro transfer printing process will be described with reference to <FIG> and <FIG> shows a micro transfer printing process for printing a plurality of pixel driving micro integrated chips on a photodiode layer in accordance with at least one embodiment.

Referring to <FIG> and <FIG>, at step S6061, pixel driving integrated chips (ICs) <NUM> may be fabricated in source silicon wafer <NUM>. A CMOS process may be performed in order to fabricate an IC with high precision (e.g., micrometer level) to provide a high image quality. Then, at step S6062, pixel driving integrated chips (ICs) <NUM> on source silicon wafer <NUM> may be transferred onto elastomer stamp <NUM>. At step S6063, pixel driving integrated chips <NUM> may be printed on print adhesive layer <NUM> on photodiode layer <NUM> by pressing elastomer stamp <NUM> on target panel <NUM> (e.g., print adhesive layer <NUM> on photodiode layer <NUM>) with predetermined conditions. At step S6064, elastomer stamp <NUM> may be removed after printing.

Referring back to <FIG>, for example, a height of each pixel driving IC may be shorter than about <NUM>. Furthermore, a thickness from bottom common electrode <NUM> to print adhesive layer <NUM> may be thinner than about Sum.

At step S6070, third contact holes <NUM> may be formed at both sides of each pixel driving IC <NUM> to expose first metal contact layer <NUM> through second ILD2 layer <NUM> and print adhesive layer <NUM>, as shown in <FIG>.

At step S6080, second metal contact layer <NUM> may be formed to fill third contact holes <NUM> and connect both ends of pixel driving IC <NUM> in accordance with at least one embodiment, as shown in <FIG>. Accordingly, each end of pixel driving IC <NUM> may be connected to corresponding photodiode <NUM>.

In accordance with another embodiment of the present disclosure, pixel driving IC <NUM> may be formed directly on first ILD layer <NUM> and connected to corresponding photodiodes <NUM> without forming second ILD layer <NUM> and print adhesive layer <NUM> when first ILD layer <NUM> has moisture proofing priority and adhesive priority, as shown in <FIG>. In this case, a manufacturing method may be further simplified.

In accordance with still another embodiment of the present disclosure, pixel driving IC <NUM> may be formed directly on second ILD <NUM> layer <NUM> and connected to corresponding pixels <NUM> without forming print adhesive layer <NUM> when second ILD <NUM> layer <NUM> has moisture proofing priority and adhesive priority, as shown in <FIG>.

Referring back to <FIG>, surface passivation layer <NUM> is formed on print adhesive layer <NUM> and pixel driving ICs <NUM> at step S6090. Scintillator layer <NUM> may be formed on the surface passivation layer <NUM> at step S6100, as shown in <FIG>.

By forming scintillator layer <NUM> on the pixel driving ICs <NUM> and passivation layer <NUM>, pixel area <NUM> of front side illumination X-ray detector <NUM> may be completely manufactured. X-ray detector <NUM> may be manufactured as a back side illumination type X-ray detector in accordance with another embodiment. Hereinafter, a method for manufacturing a pixel area of the back side illumination type X-ray detector will be described with reference to <FIG>.

<FIG> are cross-sectional views schematically illustrating a process of manufacturing a back side illumination type X-ray detector in accordance with at least one embodiment.

Referring back to <FIG>, a sacrificing layer <NUM> is formed on insulating substrate <NUM>, and a barrier layer <NUM> is formed on the sacrificing layer <NUM> at step S6010. The sacrificing layer <NUM> is formed for laser lift off (LLO). The barrier layer <NUM> is made of PI. After forming the barrier layer <NUM>, photodiode layer <NUM> and driving layer <NUM> may be formed on the barrier layer <NUM> similar to processes shown in <FIG>.

After forming photodiode layer <NUM> and driving layer <NUM> at step S6080, a laser lift-off process may be performed for removing the glass layer <NUM> and the sacrificing layer <NUM> at step S6110 as shown in <FIG>. Since glass layer <NUM> is remove, the durability of X-ray detector <NUM> may be enhanced in accordance with at least one embodiment.

Referring to <FIG>, after the laser lift-off process S6110, a flipping process is performed for flipping the resultant of photodiode layer <NUM> and driving layer <NUM> at step S6120 and placed on adhesive layer <NUM> formed on carrier substate <NUM> made of a carbon graphite at step S6130.

Referring to <FIG>, scintillator layer <NUM> is formed on barrier layer <NUM> at S6130. By forming scintillator layer <NUM> on barrier layer <NUM>, the pixel area of back side illumination type X-ray detector may be formed completely.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention.

As used in this application, the word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion.

Additionally, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

Moreover, the terms "system," "component," "module," "interface,", "model" or the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers.

The present invention can be embodied in the form of methods and apparatuses for practicing those methods. The present invention can also be embodied in the form of program code embodied in tangible media, non-transitory media, such as magnetic recording media, optical recording media, solid state memory, floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The present invention can also be embodied in the form of program code, for example, whether stored in a storage medium, loaded into and/or executed by a machine, or transmitted over some transmission medium or carrier, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code segments combine with the processor to provide a unique device that operates analogously to specific logic circuits. The present invention can also be embodied in the form of a bitstream or other sequence of signal values electrically or optically transmitted through a medium, stored magnetic-field variations in a magnetic recording medium, etc., generated using a method and/or an apparatus of the present invention.

It should be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments of the present invention.

As used herein in reference to an element and a standard, the term "compatible" means that the element communicates with other elements in a manner wholly or partially specified by the standard, and would be recognized by other elements as sufficiently capable of communicating with the other elements in the manner specified by the standard. The compatible element does not need to operate internally in a manner specified by the standard.

Claim 1:
A system to operate an X-ray detector (<NUM>) comprising:
a photodiode layer including a plurality of photodiodes (PD1, PD2, PD3, ...) and configured to receive X-ray that have passed through a target object and convert the received X-ray to electric signals; and
a plurality of pixel driving micro integrated chips ICs (<NUM>) each coupled to two or more photodiodes in the photodiode layer,
wherein the plurality of pixel driving micro integrated chips is manufactured separately from the photodiode layer and attached on the photodiode layer,
characterized in that
the pixel driving micro integrated chips each are coupled to two or more photodiodes in the photodiode layer and
the plurality of pixel driving micro integrated chips are adapted to sequentially turn on corresponding switches (<NUM>-<NUM>) of the coupled photodiodes, sequentially read data accumulated in the coupled photodiodes, and sequentially output read data to a data driver circuit.