Abstract:
A structure of X-ray detector includes a Si-rich dielectric material for serving as a photo-sensing layer to increase light sensitivity. The fabrication method of the X-ray detector including the Si-rich dielectric material needs less photolithography-etching processes, so as to reduce the total thickness of thin film layers and decrease process steps and cost.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to an X-ray detector and a fabrication method of X-ray detector, and more particularly, to an X-ray detector by utilizing a silicon-rich (Si-rich) dielectric layer as photo-sensing material and a fabrication method thereof. 
     2. Description of the Prior Art 
     In contrast to the traditional negative-type X-ray detector system, a digital X-ray flat indirect detector system has advantages of low irradiation and fast imaging of electric images. In addition, the images of digital X-ray flat indirect detector system is easily to be viewed, reformed, extracted, transferred, and analyzed. Therefore, the digital X-ray flat indirect detector system has been a mainstream in current medical digital image technology. A digital X-ray flat indirect detector system includes a sensing pixel array, and each sensing pixel includes a thin film transistor (TFT), a photo-sensing device and a luminous material that transforms X-ray into visible light. Generally, the photo-sensing devices of a traditional digital X-ray flat indirect detector system are mainly formed with P-type/intrinsic/N-type (PIN) photodiodes that are composed of amorphous silicon materials. However, a PIN photodiode has a very large thickness, which is about 1-2 micrometers (μm), and is conductive itself. Therefore, many isolation layers have to be formed around the PIN photodiode in order to avoid short defect occurring between the PIN photodiode and adjacent devices, such as sensing electrodes. As a result, the fabrication process that integrates the PIN photodiodes and the sensing pixel array having devices such as TFTs usually includes 12 to 13 steps of thin-film deposition processes and photolithography-etching processes, which spends a lot of time and costs much money. Accordingly, it is still an important issue for manufacturers of X-ray detector system to keep on researching in order to design new structure or new photo-sensing materials that can effectively replace PIN photodiodes for fabricating digital X-ray flat indirect detector system through simple processes. 
     SUMMARY OF THE INVENTION 
     It is one of the objectives of the present invention to provide an X-ray detector by utilizing Si-rich dielectric material to form photo-sensing devices, such that the above-mentioned problems of complex fabrication process and high cost of the traditional X-ray detector resulting from integrating the fabrication process of PIN photodiode and TFT elements can be solved. 
     The present invention provides a fabrication method of X-ray detector. According to the fabrication method, a substrate comprising a photo-sensing area is provided, and a patterned first conductive layer is formed on the substrate. The patterned first conductive layer comprises at least a gate positioned in the photo-sensing area. Then, a gate insulating layer is formed on the substrate to cover the surface of the gate. After that, a patterned semiconductor layer and a patterned second conductive layer are successively formed on the surface of the gate insulating layer, wherein the patterned semiconductor layer comprises a semiconductor channel region disposed on the surface of the gate insulating layer above the gate, and the patterned second conductive layer comprises a source and a drain disposed on the patterned semiconductor layer and at two sides of the semiconductor channel region respectively. Following that, a patterned dielectric layer is formed on the substrate, and the patterned dielectric layer has at least a first via hole that exposes a portion of the drain. A patterned third conductive layer is formed on the substrate, which comprises a bottom sensing electrode positioned in the photo-sensing area and is electrically connected to the drain through the first via hole. The patterned third conductive layer is positioned above the patterned semiconductor layer. A patterned Si-rich dielectric layer is formed on the substrate, disposed on the surface of the bottom sensing electrode. Then, a patterned transparent conductive layer is formed on the substrate. The patterned transparent conductive layer comprises at least a top sensing electrode covering the patterned Si-rich dielectric layer. A passivation layer is then formed on the substrate to cover the patterned transparent conductive layer. Finally, a scintillator layer is formed above the substrate and the passivation layer. The scintillator layer corresponds to the patterned Si-rich dielectric layer. 
     The present invention further provides an X-ray detector that comprises: a substrate comprising a photo-sensing area; a patterned first conductive layer disposed on the substrate, which comprises at least a gate positioned in the photo-sensing area; a gate insulating layer disposed on the substrate and covering the gate; a patterned semiconductor layer disposed on the surface of the gate insulating layer above the gate and comprising a semiconductor channel region; a patterned second conductive layer comprises at least a source and a drain disposed on the patterned semiconductor layer and positioned at two sides of the semiconductor channel region respectively; a dielectric layer disposed on the surface of the substrate and covering a portion of the patterned second conductive layer and the semiconductor channel region, wherein the dielectric layer has a first via hole that exposes a portion of the drain; a patterned third conductive layer that comprises a bottom sensing electrode positioned in the photo-sensing area, wherein the bottom sensing electrode is disposed on the patterned semiconductor layer and electrically connected to the drain through the first via hole; a patterned Si-rich dielectric layer disposed on the bottom sensing electrode; a patterned transparent conductive layer comprises a top sensing electrode disposed on the surface of the patterned Si-rich dielectric layer; a passivation layer covering the patterned transparent conductive layer; and a scintillator layer disposed above the passivation layer, corresponding to the patterned Si-rich dielectric layer. 
     The present invention even further provides a fabrication method of an X-ray detector. First, a substrate comprises a photo-sensing area is provided, and a TFT including a gate, a gate insulating layer, a patterned semiconductor layer, a source, and a drain is formed on the substrate. Then, a dielectric layer is formed on the substrate, which comprises at least a first via hole that exposes a portion of the drain. A patterned third conductive layer is formed on the substrate, wherein the patterned third conductive layer comprises a bottom sensing electrode positioned in the photo-sensing area and electrically connected to the drain through the first via hole. The patterned third conductive layer is disposed above the patterned semiconductor layer. Sequentially, a patterned Si-rich dielectric layer is formed on the substrate, which is disposed on the surface of the bottom sensing electrode. A patterned transparent conductive layer is then formed on the substrate, which comprises at least a top sensing electrode covering the patterned Si-rich dielectric layer. Finally, a passivation layer is formed on the substrate to cover the patterned transparent conductive layer, and a scintillator layer is formed above the substrate, disposed on the passivation layer. The scintillator layer corresponds to the patterned Si-rich dielectric layer. 
     It is an advantage that the X-ray detector of the present invention utilizes Si-rich dielectric materials as its photo-sensing material, such that additional dielectric layers or isolation layers are no needed to be formed for isolating the patterned Si-rich dielectric layer. Therefore, the fabrication process and cycle time can be saved. In addition, the thickness of the patterned Si-rich dielectric layer may be less than 0.5 um, which reduces the whole thickness of the X-ray detector that has several thin films and the raw material cost. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of the equivalent circuit layout of an X-ray detector according to the present invention. 
         FIG. 2  is a partial sectional schematic diagram of the X-ray detector of the present invention shown in  FIG. 1 . 
         FIGS. 3-8  are schematic diagrams showing the fabrication method and sectional-views of the X-ray detector according to a first embodiment of the present invention. 
         FIGS. 9-12  are schematic diagrams showing the fabrication method of the X-ray detector according to a second embodiment of the present invention. 
         FIG. 13  is a schematic sectional view of an X-ray detector according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 ,  FIG. 1  is an equivalent circuit layout diagram of an X-ray detector  10  according to the present invention. The X-ray detector  10  of the present invention comprises a substrate  12 , wherein a photo-sensing area  14  and a periphery area  16  at a side of the photo-sensing area  14  are disposed thereon. The photo-sensing area  14  comprises a plurality of sensing pixels  18  arranged as an array, which are defined by pluralities of scan lines  20  and readout lines  22  perpendicular to the scan lines  20 . Each sensing pixel  18  includes at least a TFT  24  and a photo-sensing device  26 . The substrate  12  further comprises a plurality of top electrode lines  28  parallel to the readout lines  22 , each of which individually passes through pluralities of sensing pixels  18  and is electrically connected to the top sensing electrodes of the photo-sensing devices  26  in the sensing pixels  18  it passes through. On the other hand, a plurality of first contact pads  30  and a plurality of second contact pads  32  are disposed in the periphery area  16 , wherein the first contact pads  30  may be electrically connected to the scan lines  20  and the second contact pads  32  may be electrically connected to the readout lines  22 . A plurality of third contact pads  33  may be selectively disposed in the periphery area  16  and electrically connected to the top electrode lines  28 . 
     Referring to  FIG. 2 ,  FIG. 2  is a sectional schematic diagram of the partial X-ray detector  10  of the present invention shown in  FIG. 1 , wherein only one sensing pixel  18  is shown in  FIG. 2  for illustration. The X-ray detector  10  of the present invention comprises a patterned first conductive layer  34  disposed on the surface of the substrate  12 . The first conductive layer  34  includes a gate  36  of the TFT  24  of each sensing pixel  18  and the first contact pads  30  positioned in the periphery area  16  (only one first contact pad  30  is shown in  FIG. 2 ). The X-ray detector  10  further comprises a gate insulating layer  38  disposed on the surface of the substrate  12  and covering the gate  36  and a portion of the first contact pad  30 . A patterned semiconductor layer  40  is disposed on the gate insulating layer  38  and comprises a semiconductor channel region  42  disposed on the surface of the gate insulating layer  38  above the gate  36 . The patterned semiconductor layer  40  may comprise amorphous silicon materials. 
     In addition, the X-ray detector  10  comprises a patterned second conductive layer  46  disposed on the gate insulating layer  38 , covering a portion of the patterned semiconductor layer  40 . A patterned doped semiconductor layer  44  may be selectively disposed between the patterned semiconductor layer  40  and the patterned second conductive layer  46 , which may be composed of doped amorphous silicon materials for example. The patterned second conductive layer  46  comprises at least a drain  52 , a source  54 , a top electrode line  28 , a second contact pad  32 , and a third contact pad  33  (shown in  FIG. 1 ). Wherein, the drain  52  and the source  54  are disposed above and at two sides of the semiconductor channel region  42 , and form the TFT  24  together with the gate  36 , the gate insulating layer  38 , and the semiconductor channel region  42 . The top electrode line  28  is disposed at a side of the TFT  24 , and the second contact pad  32  is positioned in the periphery area  16 . A patterned dielectric layer  56  is further disposed on the substrate  12  and covers the TFT  24 , the first contact pad  30 , the second contact pad  32 , and the top electrode line  28 . The patterned dielectric layer  56  has a first via hole  58  that exposes a portion of the drain  52 , a second via hole  60  that exposes the top electrode line  28 , a third via hole  62  that exposes the first contact pad  30 , and at least a fourth via hole  64  that exposes the second contact pad  32  or the third contact pad  33 . In addition, the X-ray detector  10  comprises a patterned third conductive layer  66  disposed on the surface of the patterned dielectric layer  56 , wherein portions of the patterned third conductive layer  66  are filled in the first via hole  58 , the second via hole  60 , the third via hole  62 , and the fourth via hole  64 . The patterned third conductive layer  66  includes a plurality of bottom sensing electrodes  68  in each sensing pixel  18  respectively. Each bottom sensing electrode  68  is electrically connected to the corresponding drain  52  through the first via hole  58 . In addition, the portion of the patterned third conductive layer  66  filled in the second via hole  60  may serve as a contact device  70  for electrically connecting the top electrode line  28  and a top sensing electrode  84 . However, in other embodiments, the X-ray detector  10  may not include the top electrode line  28  shown in  FIG. 2  while the portion of the patterned third conductive layer  66  electrically connected to the top sensing electrode  84  directly serves as a top electrode line itself. In addition, the patterned third conductive layer  66  disposed in the third via hole  62  serves as a first contact plug  72  for electrically connecting an external circuit and the first contact pad  30 , and the patterned third conductive layer  66  disposed in the fourth via hole  64  serves as a second contact plug  74  which is electrically connected to the second contact pad  32  or the third contact pad  33 . 
     Furthermore, the X-ray detector  10  comprises a patterned Si-rich dielectric layer  78  disposed on the surface of the bottom sensing electrode  68  for serving as photo-sensing material. The patterned Si-rich dielectric layer  78  comprises a plurality of sensor units  76  disposed in each sensing pixel  18  respectively. The material of the patterned Si-rich dielectric layer  78  can be such as Si-rich silicon oxide (SiOx), Si-rich silicon nitride (SiNy), Si-rich silicon oxynitride (SiOxNy), Si-rich silicon carbide (SiCz), Si-rich silicon oxycarbide (SiOxCz), hydrogenated Si-rich silicon oxide (SiHwOx), hydrogenated Si-rich silicon nitride (SiHwNy), hydrogenated Si-rich silicon oxynitride (SiHwOxNy) or a combination of the aforementioned materials, wherein 0&lt;w&lt;4, 0&lt;x&lt;2, 0&lt;y&lt;1.67, 0&lt;z&lt;1, or may comprise combinations of silicon, oxygen, nitrogen, carbon, hydrogen and other materials. A patterned transparent conductive layer  82  is further disposed on the surface of the patterned Si-rich dielectric layer  78 , comprising a plurality of top sensing electrodes  84  disposed in each sensing pixel  18  respectively. Each top sensing electrode  84  is electrically connected to the corresponding top electrode line  28  through the contact device  70 . As a result, the photo-sensing device  26  of each sensing pixel  18  is composed of the bottom sensing electrode  68 , the sensor unit  76 , and the top sensing electrode  84 . The X-ray detector  10  further comprises a passivation layer  90  and a scintillator layer  92 , wherein the passivation layer  90  covers the patterned transparent conductive layer  82  and a portion of the patterned third conductive layer  66 . In this embodiment, the passivation layer  90  includes an inorganic passivation layer  86  with a small thickness and a thicker organic planarization layer  88  disposed above the inorganic passivation layer  86 . The scintillator layer  92  is disposed on the surface of the organic planarization layer  88 , corresponding to the patterned Si-rich dielectric layer  78 . The scintillator layer  92  preferably covers the whole photo-sensing area  14  shown in  FIG. 1 . The scintillator layer  92  may be made of cesium iodide (CsI) or related compounds or materials for transforming the X-ray into a visible light. As shown in  FIG. 2 , when X-ray illuminates the X-ray detector  10  from the top side, the scintillator layer  92  transforms X-ray into visible light (with a wavelength of about 450-650 nanometers) downward. Under the illumination of visible light, the sensor unit  76  will produce photocurrent, which will be output as a readout signal (or called sensing signal) through the readout lines  22  in cooperation with the bottom sensing electrodes  68 , the TFTs  24 , and the scan lines  20 , such that a detected X-ray image can be obtained. 
     The fabrication method of the present invention X-ray detector  10  is shown in  FIGS. 3-8 . First, the substrate  12  is provided as shown in  FIG. 3 . The substrate  12  comprises the periphery area  16  and the photo-sensing area  14 , wherein the photo-sensing area  14  includes a plurality of sensing pixels  18  arranged as an array in the photo-sensing area  14 . Then, the patterned first conductive layer  34  is formed on the surface of the substrate  12 , which comprises the gate  34  positioned in each sensing pixel  18  and at least a first contact pad  30  positioned in the periphery area  16 . 
     Referring to  FIG. 4 , a gate insulating layer  38 , a semiconductor layer  40 ′, a doped semiconductor layer  44 ′ (such as a doped amorphous silicon layer), and a second conductive layer  46 ′ are successively formed on the substrate  12 . After that, a photoresist layer  48  is formed on the second conductive layer  46 ′, and a half-tone photomask  50  is utilized to perform a photolithography-etching process to the thin film layers on the substrate  12 . The half-tone photomask  50  includes a transparent region  50   a , an opaque region  50   b , and a half-tone region  50   c . The opaque region  50   b  corresponds to the patterns of the patterned second conductive layer  46  shown in  FIG. 2 , such as the second contact pad  32 , the third contact pad  33 , the top electrode line  28 , the drain  52 , and the source  54 . The transparent region  50   a  corresponds to a portion of the second conductive layer  46 ′ predetermined to be removed. The half-tone region  50   c  corresponds to the portion of the semiconductor channel region  42  positioned between the drain  52  and the source  54 . After the photolithography and development processes, the remaining photoresist layer  48  is shown in  FIG. 4 . 
     Sequentially, the patterned photoresist layer  48  is used as an etching mask to perform the etching process for removing portions of the second conductive layer  46 ′, the doped semiconductor layer  44 ′, and the semiconductor layer  40 ′ until the surface of the gate insulating layer  38  is exposed, so as to form the patterned second conductive layer  46 , the patterned doped semiconductor layer  44 , and the patterned semiconductor layer  40 , as shown in  FIG. 5 . The patterned second conductive layer  46  comprises the drain  52  and the source  54  disposed at two sides of the gate  34  and above the gate  34 . The portion of the patterned semiconductor layer  40  positioned between the gate  34 , the drain  52 , and the source  54  serves as the semiconductor channel region  42 . In addition, the doped semiconductor layer  44  disposed below the drain  52  and source  54  serves as an ohmic contact layer. 
     With reference to  FIG. 6 , a patterned dielectric layer  56  is then formed on the substrate  12 . The patterned dielectric layer  56  comprises the first via hole  58 , the second via hole  60 , the third via hole  62  and the fourth via hole  64  exposing portions of the drain  52 , the top electrode line  28 , the first contact pad  30 , and the second contact pad  32  or and the third contact pad  33  respectively. Referring to  FIG. 7 , a patterned third conductive layer  66  is formed on the substrate  12 . The patterned third conductive layer  66  comprises a plurality of bottom sensing electrodes  68  positioned in each sensing pixel  18  respectively, at least one contact device  70  disposed in the second via hole  60 , at least one first contact plug  72  disposed in the third via hole  62 , and at least one second contact plug  74  disposed in the fourth via hole. Wherein, the bottom sensing electrode  68 , the contact device  70 , the first contact plug  72 , and the second contact plug  74  are electrically connected to the drain  52 , the top electrode line  28 , the first contact pad  30 , and the second contact pad  32  or the third contact pad  33  respectively. 
     Following that, the patterned Si-rich dielectric layer  78  is formed on the substrate  12 . The patterned Si-rich dielectric layer  78  is disposed on the surface of the bottom sensing electrode  68  for serving as a photo-sensing material of the X-ray detector  10 , which comprises a plurality of sensor units  76  positioned in each sensing pixel  18  respectively. The patterned Si-rich dielectric layer  78  may be, such as Si-rich SiOx, Si-rich SiNy, Si-rich SiOxNy, Si-rich SiCz, Si-rich SiOxCz, hydrogenated Si-rich SiHwOx, hydrogenated Si-rich SiHwNy, hydrogenated Si-rich SiHwOxNy, or the combinations of the above materials and other materials. 
     Then, as shown in  FIG. 8 , a patterned transparent conductive layer  82  is formed on the surface of the patterned Si-rich dielectric layer  78 . The patterned transparent conductive layer  82  comprises a plurality of top sensing electrodes  84  respectively disposed in each sensing pixel  18  and electrically connected to the corresponding top electrode line  28  through the contact device  70 . Therefore, the photo-sensing device  26  in each sensing pixel  18  is composed of the bottom sensing electrode  68 , the sensor unit  76 , and the top sensing electrode  84 . 
     Sequentially, a passivation layer  90  is formed on the substrate  12 , which comprises an inorganic passivation layer  86  and an organic planarization layer  88  covering the photo-sensing area  14  but exposing the first contact plug  72  and the second contact plug  74 . Referring to  FIG. 2 , a scintillator layer  92  is then formed on the organic planarization layer  86  to cover the photo-sensing area  14 . The formation step of the scintillator layer  92  may include a coating process or an evaporation process. In other embodiment, the scintillator layer  92  may be formed through an attaching process. After the formation of the scintillator layer  92 , the fabrication of the X-ray detector  10  according to the first embodiment of the present invention is completed. As a result, the whole fabrication process of the X-ray detector  10  only needs seven photolithography-etching processes. 
     With reference to  FIG. 9  to  FIG. 12 , the fabrication process of the X-ray detector according to a second embodiment of the present invention is shown in  FIG. 9  to  FIG. 12 . The difference between this embodiment and the first embodiment includes that no half-tone photomask is used during the fabrication process. Therefore, one more photolithography-etching process is needed in this embodiment. Furthermore, the scintillator layer  92  of this embodiment is formed on another substrate. Referring to  FIG. 9 , the similar devices of the X-ray detector  10 ′ of the second embodiment is represented with the same numerals shown in the first embodiment. First, the patterned first conductive layer  34  and the gate insulating layer  38  are formed on the substrate  12  through formation processes similar to the previous embodiment. Then, a semiconductor layer and a doped semiconductor layer (not shown) are successively blanketly deposited on the substrate  12 , and a photolithography-etching process is performed to remove portions of the semiconductor layer and the doped semiconductor layer at the same time so as to form the patterned semiconductor layer  40  and the patterned doped semiconductor layer  44 . 
     Sequentially, as shown in  FIG. 10 , a second conductive layer (not shown) is deposited on the substrate  12 . After a further photolithography-etching process is performed, a portion of the second conductive layer and a portion of the doped semiconductor layer  44  are removed so as to form the patterned second conductive layer  46  that comprises the drain  52  and the source  54  at two sides of the semiconductor channel region  42  and above the gate  36 , the top electrode line  28  at a side of the gate  36 , and the second contact pad  32  (and the third contact pad  33  as shown in  FIG. 1 ) positioned in the periphery area  16 . 
     Referring to  FIG. 11 , a patterned dielectric layer  56  is then formed on the substrate  12 , wherein the patterned dielectric layer  56  comprises a first via hole  58 , a second via hole  60 , a third via hole  62 , and a fourth via hole  64  that respectively expose portions of the drain  52 , the top electrode line  28 , the first contact pad  30 , and the second contact pad  32  or the third contact pad  33 . As shown in  FIG. 12 , similar to the formation process of the first embodiment, a patterned third conductive layer  66 , a patterned Si-rich dielectric layer  78 , and a patterned transparent conductive layer  82  are successively formed on the substrate  12  so as to form electric devices such as the bottom sensing electrode  68 , the sensor unit  76 , and the top sensing electrode  84 . Then, a passivation layer  86  is formed to cover the devices on the substrate  12 , which exposes portions of the first and second contact pads  30 ,  32 . In addition, the fabrication method of the present invention X-ray detector  10 ′ further comprises providing a substrate  94  and forming a scintillator layer  92  on the surface of the substrate  94 , wherein the formation method of the scintillator layer  92  may include a coating process, an evaporation process, or an attaching process. For example, a thin film comprises CsI material may be attached onto the surface of the substrate  94 . Finally, the substrate  94  and the substrate  12  are assembled to make the scintillator layer  92  correspond to the photo-sensing area  14  or the patterned Si-rich dielectric layer  78 . Therefore, when X-ray illuminates the scintillator layer  92  on the substrate  94  from the top side, the scintillator layer  92  will transform X-ray into visible light such that the photo-sensing device  26  positioned below the scintillator layer  92  can detect the visible light. In this embodiment, only eight photolithography-etching processes are needed for completing the fabrication process of the X-ray detector  10 ′. 
     With reference to  FIG. 13 ,  FIG. 13  is a schematic diagram of an X-ray detector  100  according to a third embodiment of the present invention. In this embodiment, the TFT of the X-ray detector  100  is formed through three photolithography-etching processes, and the scintillator layer  92  is directly formed on the surface of the passivation layer  90 . It should be noted that the patterned transparent conductive layer  82  further covers the surfaces of the first and the second contact plugs  72 ,  74 . The patterned transparent conductive layer  82  preferably comprises indium tin oxide (ITO) materials. Since ITO has high stability, the patterned transparent conductive layer  82  may provide a function to protect the first and second contact plugs  72 ,  74 . 
     In addition, in other embodiments, the patterned second conductive layer  46  may do not include the top electrode line  28  shown in  FIG. 13 . In contrary, a portion of the patterned third conductive layer  66  is utilized to serve as the top electrode line and to substitute the top electrode line  28  composed of the patterned second conductive layer  46  of the third embodiment. Furthermore, in various embodiments of the present invention, the disposition of the contact device  70  can be omitted, while a portion of top sensing electrode  84  of the patterned transparent conductive layer  82  is filled into the second via hole  60  and is electrically connected to the top electrode line  28  directly. Alternatively, a portion of the patterned transparent conductive layer  82  may be used as the top electrode line, thus it is not needed to form the top electrode line  28  formed by the patterned second conductive layer  46  and the contact device  70  formed by the patterned third conductive layer  66 . 
     As a result, the X-ray detector of the present invention is a kind of X-ray flat indirect detector system, wherein the scintillator layer is used for transforming X-ray into visible light and Si-rich dielectric layer is used as the photo-sensing material of the photo-sensing device. In contrast to the prior art, it only needs seven to eight photolithography-etching processes for fabricating the essential thin-film devices of the present invention X-ray detector. Therefore, the number of photomasks used in the whole fabrication process and manufacture cost can be effectively reduced. In addition, the thickness of the Si-rich dielectric layer can be smaller than about 0.5 μm, such that the X-ray detector of the present invention has advantages of low cost and high yield. Furthermore, besides medical X-ray photography system, the present invention X-ray detector may be applied to electron microscopy or other photo-sensing devices with X-ray image scanning system or X-ray photography system. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.