WO2013038815A1 - Image sensor and radiography device - Google Patents
Image sensor and radiography device Download PDFInfo
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- WO2013038815A1 WO2013038815A1 PCT/JP2012/068903 JP2012068903W WO2013038815A1 WO 2013038815 A1 WO2013038815 A1 WO 2013038815A1 JP 2012068903 W JP2012068903 W JP 2012068903W WO 2013038815 A1 WO2013038815 A1 WO 2013038815A1
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Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14632—Wafer-level processed structures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
- H01L27/14687—Wafer level processing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
Definitions
- the present invention relates to an image sensor and a radiographic image capturing apparatus, and more particularly to an image sensor in which a plurality of conversion units are arranged two-dimensionally and a radiographic image capturing apparatus using the image sensor.
- An image sensor that captures an image by generating electric charges according to the amount of light such as visible light irradiated by a conversion unit arranged in a two-dimensional form (matrix form) and converting the electric signal into an electric signal is known.
- a conversion unit arranged in a two-dimensional form (matrix form) and converting the electric signal into an electric signal.
- an apparatus using such an image sensor for example, after converting irradiated radiation such as X-rays into light of other wavelengths such as visible light with a scintillator or the like, it is converted into energy of the irradiated light.
- various radiographic imaging apparatuses have been developed that generate charges in a converter such as a photodiode and convert them into electrical signals (that is, image data).
- This type of radiographic imaging device is known as an FPD (Flat Panel Detector) and has been conventionally formed as a so-called special-purpose machine that is integrally formed with a support base (see, for example, Patent Document 1).
- FPD Full Panel Detector
- Patent Document 1 portable radiographic image capturing apparatuses that can accommodate two-dimensionally arranged conversion units in a housing and are portable have been developed and put into practical use (for example, see Patent Documents 2 and 3).
- a plurality of conversion units A are two-dimensionally arranged on a substrate, and one of the conversion units A is arranged.
- a signal line Si is connected to the electrode Aa on the side through a thin film transistor (Thin-Film-Transistor, hereinafter referred to as TFT) as a switch element.
- TFT Thin-Film-Transistor
- the scanning line Ga to which a voltage for turning on / off the TFT is normally applied is connected to the gate electrode G of each TFT.
- S and D in FIG. 17 represent a source electrode and a drain electrode of the TFT, respectively.
- bias line B is connected to the electrode Ab on the other side of each conversion unit A.
- a bias voltage is applied to each conversion unit A from the bias power supply Pb via the bias line B.
- a bias voltage in a direction in which no current flows in each converter A that is, a so-called reverse bias voltage, is applied instead of a direction in which current flows in each converter A.
- the generated holes move to the electrode having the lower potential (ie, the electrode Ab to which the bias line B is connected), and the generated electrons are signaled via the electrode having the higher potential (ie, the TFT, for example). It moves to the electrode Aa) side connected to the line Si.
- the electrode having the lower potential ie, the electrode Ab to which the bias line B is connected
- the generated electrons are signaled via the electrode having the higher potential (ie, the TFT, for example). It moves to the electrode Aa) side connected to the line Si.
- an ON voltage is applied to the gate electrode G of the TFT, so that electrons (or holes, hereinafter collectively referred to as charges) are emitted from the conversion part A to the signal line Si.
- the electric charge flows through the signal line Si and flows into the readout circuit Cro, and is converted into image data by the readout circuit Cro.
- the image data corresponding to the electric charges generated in each conversion unit A due to the irradiation of radiation is configured to be read out.
- JP-A-9-73144 JP 2006-058124 A Japanese Patent Laid-Open No. 6-342099
- the conversion unit can be configured with a simpler structure. It was. More specifically, it has been found that the switch element of the conversion unit can be configured with a simpler structure rather than a switch element having a complicated configuration such as the above-described TFT.
- the present invention has been made in view of the above problems, and in an image sensor in which a plurality of conversion units are arranged two-dimensionally, an image using a conversion unit including a switch element with a more simplified structure. It is an object of the present invention to provide a sensor and to provide a radiographic image capturing apparatus using the sensor.
- the image sensor of the present invention includes: A plurality of converters including a first electrode and a second electrode arranged two-dimensionally on a substrate; Each resistance switch that is provided so as to be electrically connected to the first electrode of each of the conversion units, and whose resistance value changes by voltage application; Each signal line wired so as to be connected to each of the resistance switches for each column of the conversion units arranged two-dimensionally, For each row of each of the converters arranged in a two-dimensional manner, each bias line wired to be connected to the second electrode of each converter, and applying a voltage to each converter, A switching driver for switching the voltage value of the voltage applied to each bias line; Each readout circuit provided for each of the signal lines, which converts the charges discharged from the conversion unit to the corresponding signal lines into image data and reads out the image data; Control means for controlling the operation of at least the switching driver and each readout circuit to read out the image data from the respective conversion units to read out the electric charges generated in the respective conversion units by the light
- the radiographic imaging device of the present invention is The image sensor of the present invention, When irradiated with radiation, a scintillator that converts the radiation into light and outputs the light to each of the conversion units; It is characterized by providing.
- the resistance switch is used as the switch element of each conversion unit, for example, as shown in FIG. It becomes possible to further simplify.
- the resistance switch when used as the switching element of each conversion unit in this way, the on / off operation of the resistance switch, that is, the transition between the high resistance state and the low resistance state is performed via the bias line.
- the voltage applied to each converter since a TFT is not used as a switching element as in the conventional conversion unit A shown in FIG. 17, a scanning line for applying a voltage for turning on / off the TFT to an image sensor or a radiographic imaging device. There is no need to provide Ga.
- the scanning line Ga is not provided, a beneficial effect such as an increase in the degree of freedom of layout of the conversion unit, the resistance switch, the signal line, the bias line, etc. on the substrate of the image sensor or the radiographic imaging apparatus is obtained. It is done. Further, it has been necessary to repeatedly perform a complicated process for forming a TFT, but the resistance switch can be performed by a simpler method using a shadow mask, for example.
- the conversion unit can be manufactured by a simple manufacturing process, and the conversion unit, the image sensor, and the radiographic imaging device can be manufactured by a simpler production process. For this reason, it is possible to improve the productivity of the conversion unit, the image sensor, and the radiation image capturing apparatus, and it is also possible to obtain a beneficial effect that the yield in production can be improved. .
- FIG. 2 is a cross-sectional view taken along line XX in FIG. It is a perspective view showing the state which connected the connector of the cable to the connector of the radiographic imaging apparatus. It is a block diagram showing the equivalent circuit of the image sensor which concerns on this embodiment. It is an enlarged view of the conversion part of the image sensor which concerns on this embodiment.
- FIG. 6 is a cross-sectional view taken along line YY in FIG. It is a flowchart showing each process in the manufacturing process of the conversion part containing a resistance switch. It is a figure showing the state by which the signal line is arrange
- the image sensor may be configured to be used as an image sensor for other imaging devices such as a digital camera. It is possible, and the present invention is also applied to such a configuration.
- a so-called portable radiographic imaging apparatus will be described as the radiographic imaging apparatus.
- a radiographic imaging of a dedicated machine type also referred to as a fixed type
- the present invention can be applied to an apparatus.
- FIG. 1 is a perspective view showing an appearance of a radiographic image capturing apparatus according to the present embodiment
- FIG. 2 is a cross-sectional view taken along line XX of FIG.
- the radiation image capturing apparatus 100 includes a housing 2 in which a sensor panel SP including a scintillator 3 and a substrate 4 is accommodated.
- the up and down direction is represented in accordance with the up and down direction in FIGS. 1 and 2 (that is, the upper side in the figure is represented as “up” or “up”).
- the housing 2 is formed of a material such as a carbon plate or plastic, and the openings on both sides of the housing body 2A having the radiation incident surface R are closed by the lid members 2B and 2C. ing. Further, the lid member 2B on one side of the housing 2 has a power switch 37, a changeover switch 38, a connector 39, an indicator 40 composed of an LED or the like for displaying a battery state, an operating state of the radiographic imaging apparatus 1, and the like. Is arranged.
- a connector C provided at the tip of the cable Ca is connected to the connector 39, so that signals and data are transmitted / received to / from an external device via the cable Ca. It can be done.
- an antenna device 41 (see FIG. 4 described later) is provided on the lid member 2C on the opposite side of the housing 2, and an external device is connected via the antenna device 41. It is also possible to transmit and receive signals and data in a wireless manner.
- a base 31 is disposed inside the housing 2 via a lead thin plate (not shown) on the lower side of the substrate 4, and an electronic component 32 and the like are disposed on the base 31.
- the PCB substrate 33, the battery 22 and the like are attached.
- a glass substrate 34 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed.
- the buffer material 35 is provided between the sensor panel SP and the side surface of the housing 2.
- the scintillator 3 is provided at a position facing the detection unit P, which will be described later, on the substrate 4.
- the scintillator 3 is, for example, one that has a phosphor as a main component and converts it into light having a wavelength of 300 to 800 nm, that is, an electromagnetic wave centered on visible light when it receives radiation, and outputs it. .
- substrate 4 is comprised with the glass substrate, and on the surface 4a of the side facing the scintillator 3 of the board
- FIG. 4 is a block diagram showing an equivalent circuit of the image sensor 1 according to the present embodiment.
- CDS correlated double sampling circuit 16
- the conversion unit 5 On the substrate 4 (see FIG. 2) of the image sensor 1, as shown in FIG. 4, a plurality of converters 5 are arranged in a two-dimensional form (matrix form).
- the conversion unit 5 has a radiation incident from a radiation incident surface R (see FIG. 1 and the like) of the housing 2 of the radiographic imaging device 100, and is converted into visible light from the scintillator 3 (see FIG. 2).
- a radiation incident surface R see FIG. 1 and the like
- the conversion unit 5 converts the irradiated radiation (in this embodiment, light converted from the radiation by the scintillator 3) into electric charges.
- a region in which the plurality of conversion units 5 are two-dimensionally arranged that is, a region indicated by a one-dot chain line in FIG. 4) is the detection unit P of the image sensor 1.
- a photodiode is used as the conversion unit 5, but other than this, for example, a phototransistor or the like can also be used.
- each resistance switch 6 whose resistance value is changed by voltage application is electrically connected to the first electrode 5 a of each converter 5.
- a specific configuration of the conversion unit 5 including the resistance switch 6 according to this embodiment will be described later.
- a plurality of signal lines 7 are wired so as to be connected to the respective resistance switches 6 for each column of the respective converters 5 arranged in a two-dimensional manner.
- the resistance switch 6 accumulates electric charge in each conversion unit 5 when the resistance value is high resistance.
- the resistance switch 6 stores the electric charge accumulated in each conversion unit 5.
- the signal line 7 is emitted through the resistance switch 6.
- bias line 8 is connected to each of the second electrodes 5b of each conversion unit 5.
- One bias line 8 is wired for each row of each conversion unit 5 arranged two-dimensionally, and each bias line 8 is connected to each terminal of the switching driver 10. .
- a bias power supply 11 is connected to the switching driver 10.
- the switching driver 10 is a voltage having a predetermined voltage value supplied from the bias power supply 11 in a normal case, that is, in a case other than the image data reading process described later.
- Vbias that is, the above-described reverse bias voltage Vbias is applied to each bias line 8. Therefore, in a normal state, the reverse bias voltage Vbias is applied to the second electrode 5b of the conversion unit 5 via each bias line 8 and each connection line 8.
- the first power source that supplies the switching driver 10 with the voltage value of the voltage output from the bias power source 11 converted into a different voltage value between the switching driver 10 and the bias power source 11.
- the circuit 12a and the second power supply circuit 12b are connected to each other.
- the bias power supply 11 supplies the switching driver 10 with the reverse bias voltage Vbias having a predetermined voltage value.
- the first power supply circuit 12a has a voltage value lower than the reverse bias voltage Vbias.
- the second power supply circuit 12b supplies a voltage having a voltage value higher than the reverse bias voltage Vbias to the switching driver 10.
- the switching driver 10 is supplied with a voltage Vb to be applied to each bias line 8 from the bias power supply 11 and a reverse bias voltage Vbias supplied from the bias power supply 11 and the first power supply circuit 12a in a later-described image data read process.
- the resistance value of the resistance switch 6 is varied by switching between a voltage having a lower voltage value and a voltage having a voltage value higher than that supplied from the second power supply circuit 12b. This point will be described later.
- each signal line 7 is connected to each readout circuit 14 built in the readout IC 13.
- the readout circuit 14 includes an amplifier circuit 15 and a correlated double sampling circuit 16.
- An analog multiplexer 17 and an A / D converter 18 are further provided in the reading IC 13.
- the correlated double sampling circuit 16 is denoted as CDS.
- a reference potential V 0 such as 0 [V] is applied to each signal line 7 from each readout circuit 13 side.
- the amplifier circuit 15 when the image data is read from each conversion unit 5, the electric charge is transferred from each conversion unit 5 to the signal line 7 via a resistance switch 6 that is in a low resistance state as will be described later.
- the amplifier circuit 15 When discharged, the amplifier circuit 15 outputs a voltage value corresponding to the amount of discharged charges.
- the correlated double sampling circuit (CDS) 16 provided on the output side of the amplifier circuit 15 converts the voltage value Vin output from the amplifier circuit 15 before each charge is discharged from each converter 5 into each converter. After the electric charge is discharged from the unit 5, the voltage value Vfi output from the amplifier circuit 15 is subtracted, and a difference Vfi ⁇ Vin between these voltage values is output downstream as analog value image data. .
- the output analog value image data is sequentially transmitted to the A / D converter 18 via the analog multiplexer 17, and is sequentially converted into digital value image data by the A / D converter 18. Are output and stored sequentially.
- the image sensor 1 is used in the radiographic image capturing apparatus 100.
- a voltage value that is, a signal value normally output from the amplifier circuit 15 is used. Is small, the correlated double sampling circuit 15 is used.
- the signal value may be sufficiently larger than the noise signal. In such a case, it is not always necessary to use the correlated double sampling circuit 15 or the like.
- the control means 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a RAM (Random Access Memory), an input / output interface connected to the bus, an FPGA (Field Programmable Gate Array), etc. It is configured. It may be configured by a dedicated control circuit.
- CPU Central Processing Unit
- ROM Read Only Memory
- RAM Random Access Memory
- RAM Random Access Memory
- FPGA Field Programmable Gate Array
- the control means 20 controls the operation of each member of the image sensor 1.
- the switching driver 10 the bias power supply 11, the first power supply circuit 12 a, the second power supply circuit 12 b, the readout circuit 14, etc.
- control is performed such that image data is read out as image data by discharging electric charges from the respective converters 5 as described above. A specific control method in the image data reading process will be described later.
- the control means 20 is connected with a storage means 21 composed of SRAM (Static RAM), SDRAM (Synchronous DRAM) or the like, and a battery 22 for supplying power to each functional unit.
- a connection terminal 23 for charging the battery 22 by supplying power to the battery 22 from a charging device (not shown) is attached to the battery 22.
- the control unit 20 is connected to the antenna device 41 of the radiation image capturing apparatus 100 described above.
- FIG. 5 is an enlarged plan view of the conversion unit including the resistance switch according to the present embodiment
- FIG. 6 is a cross-sectional view of one conversion unit along line YY in FIG.
- the up and down direction is represented in accordance with the up and down direction in FIG. 6 representing each component of the conversion unit 5 (that is, the upper side in the figure is represented as “up”, “up”, etc.).
- the left-right direction is expressed in accordance with the left-right direction in FIGS.
- each component is described so that it can be easily seen, and the relative size, positional relationship, interval, thickness, etc. of each component do not necessarily reflect the actual configuration.
- FIG. 5 it is described that the spaces between the respective conversion units 5 are widened, but actually, the interval between the respective conversion units 5 is made as narrow as possible to improve the aperture ratio of each conversion unit 5. Configured.
- each conversion unit 5 includes the first electrode 5a and the second electrode 5b, and the second electrode 5b of the conversion unit 5 is connected to the bias line 8, respectively.
- a resistance switch 6 is electrically connected to each first electrode 5a of the conversion unit 5, and each resistance switch 6 is connected to each signal line for each column of each conversion unit 5 arranged two-dimensionally. 7 is connected.
- the 1st electrode 5a of the conversion part 5 and the one electrode 6c of the resistance switch 6 are made into the common electrode. That is, the first electrode 5 a functions as the first electrode 5 a of the conversion unit 5 and at the same time functions as one electrode 6 c of the resistance switch 6.
- the resistance switch 6 is electrically connected with the 1st electrode 5a of the conversion part 5 by making the 1st electrode 5a into a common electrode with the resistance switch 6 in this way. It has come to be.
- one electrode 6c of the resistance switch 6 is separated from the first electrode 5 of the conversion unit 5 on a body portion 6b described later of the resistance switch 6, for example.
- the electrode of the resistance switch 6 and the first electrode 5a of the conversion unit 5 can be directly connected by, for example, stacking the first electrode 5a of the conversion unit 5 thereon. .
- the resistance switch 6 is formed at an appropriate position on the substrate 4, and the conversion unit 5 is configured such that one electrode 6 c of the resistance switch 6 and the first electrode 5 a of the conversion unit 5 are connected by a conductive wire or the like. It is also possible to configure. Even with such a configuration, it is possible to electrically connect the resistance switch 6 and the first electrode 5a of the conversion unit 5.
- FIG. 7 is a flowchart showing each step in the manufacturing process of the conversion unit including the resistance switch.
- a signal line 7 made of a metal wire such as aluminum is arranged in advance on the substrate 4, and a resistance switch is placed on the substrate 4 and the signal line 7 as shown in FIG. 8B.
- 6 electrodes 6a are stacked (step S1 in FIG. 6).
- the electrode 6a of the resistance switch 6 is made of TiN (titanium nitride).
- the electrode 6a is provided with a recess in the vicinity of the portion connected to the signal line 7, as shown in FIG.
- the resistance value of the resistance switch 6 to be described later is determined by various elements, and as one of the elements, as shown in FIG. 9A, the main body 6b of the resistance switch 6 (not shown in FIGS. 9A and 9B). 5 may be changed depending on the bonding area of the electrode 6a and the electrode 6c sandwiched from above and below (that is, the first electrode 5a in the present embodiment; the same shall apply hereinafter) through the main body 6b.
- the manufacturing process it is necessary to accurately align the electrodes 6a and 6c of the resistance switch 6 and to accurately perform the relative arrangement of the electrodes 6a and 6c.
- the accuracy of alignment or the like may not always be good. That is, in the actual process, the position of the electrode 6c may be shifted from the design position with respect to the electrode 6a.
- the electrode 6a of the resistance switch 6 has a portion connected to the signal line 7 and a portion joined to the electrode 6c via the body portion 6b of the resistance switch 6. If a recess M is provided between them, even if the position of the electrode 6c stacked above is shifted in the left-right direction (see the arrow in the figure), one side of the joint portion between the electrode 6a and the electrode 6c of the resistance switch 6 is provided. The length a does not change, and the junction area is approximately a ⁇ b.
- the junction area can be a ⁇ b.
- the electrode 6a of the resistance switch 6 is thus stacked with the recess M as shown in FIG. 9A, so that the electrode 6a and the body portion 6b of the resistance switch 6 are stacked. Even if the position of the electrode 6c is shifted, it is possible to keep the junction area between the electrode 6a and the electrode 6c through the main body 6b of the resistance switch 6 from approximately a ⁇ b.
- the alignment of the electrode 6a and the electrode 6c of the resistance switch 6 is performed precisely. Even if this is difficult, it is possible to minimize the influence of the change in the junction area and accurately prevent the resistance value of the resistance switch 6 from deviating from the designed resistance value.
- the resistance switch 6a It is also possible to form the electrode 6a in a rectangular shape, for example, without providing a recess in the six electrodes 6a.
- the main body portion 6b of the resistance switch 6 is laminated above the electrode 6a of the resistance switch 6 (see FIG. 6).
- the main body portion 6b of the resistance switch 6 laminated thereon corresponds to the edge portion of the electrode 6a.
- a break occurs at the portion (see the arrow in the figure).
- the main body portion 6b of the resistance switch 6 is formed in a thin film having a thickness of about several nanometers to several tens of nanometers.
- the edge portion of the electrode 6a is not separated from the substrate 4 or the signal line 7 as described above, and is shown in FIGS. 6 and 8B. As described above, the edge portion of the electrode 6a is formed to be tapered.
- the following method can be adopted as a method of forming the edge portion of the electrode 6a in a tapered shape.
- the electrode 6a is stacked above the substrate 4 and the signal line 7 as shown in FIGS. 9A and 9B. Then, for example, the electrode 6a is laminated by using a shadow mask constituted by a base M1 having a shape so as to surround the electrode 6a and a mask material M2 having a planar opening of the electrode 6a to be formed.
- a shadow mask constituted by a base M1 having a shape so as to surround the electrode 6a and a mask material M2 having a planar opening of the electrode 6a to be formed.
- the main body 6b of the resistance switch 6 is formed above the electrode 6a (step S2 in FIG. 7).
- the main body portion 6b of the resistance switch 6 is formed so as to cover the electrode 6a (that is, cover the electrode 6a). Similarly to the above, even if the relative position of the main body portion 6b of the resistance switch 6 with respect to the electrode 6a is slightly shifted with respect to the electrode 6a, the main body portion 6b of the resistance switch 6 is reliably connected between the electrode 6a and the electrode 6c. This is because the electrode 6a and the electrode 6c are not in direct contact (that is, are not electrically connected).
- the electrode 6a and the electrode 6c can be configured not to be in direct contact with each other even if the resistor switch 6 is formed above the electrode 6a, the electrode 6a is not necessarily covered with the main body 6b of the resistor switch 6. do not have to.
- the resistance switch 6 includes a main body 6b made of titanium oxide (TiOx) whose resistance value is changed by an electric field formed in the resistance switch 6 when a voltage is applied. 6c (in the case of the present embodiment, the first electrode 5a) is sandwiched.
- the main body 6b of the resistance switch 6 can be a resistance switch using various known materials other than titanium oxide, and preferably, for example, Cu, Ni, Fe, Al, Hf, Zr, An oxide of a transition metal such as Ba, Sr, Ta, La, Si, or Y, or one having an oxygen defect is used. It is also possible to mix these metal oxides and metal oxides having different ratios such as oxygen (O) contained therein or to divide them into two layers.
- a layered structure is formed (step S3 in FIG. 7).
- the first electrode 5 a functions as the electrode 6 c on the opposite side of the electrode 6 a of the resistance switch 6 and also functions as one electrode of the conversion unit 5.
- the main body 5c of the converter 5 is laminated and formed above the first electrode 5a (step S4 in FIG. 7).
- the main body 5c of the conversion unit 5 is formed in an n-type by doping a group VI element into hydrogenated amorphous silicon (a-Si) sequentially from the lower side (that is, the resistance switch 6 side).
- a-Si hydrogenated amorphous silicon
- a layer 5d, an i layer 5e (so-called conversion layer) made of hydrogenated amorphous silicon, and a p layer 5f formed into a p-type by doping a hydrogenated amorphous silicon with a group III element are formed. .
- the light irradiated to the image sensor 1 (in this embodiment, the light irradiated to the radiation image capturing apparatus 1 is converted by the scintillator 3 (see FIG. 2)) enters the i layer 5e. Electron hole pairs are generated in the i layer 5e.
- ITO Indium * Tin * Oxide
- an insulating layer made of, for example, silicon nitride (SiN) or the like by sputtering or the like from above the main body 5c and the second electrode 5b of the converter 5 stacked in this way. 9 is formed to cover the resistance switch 6 and the main body 5c (step S6 in FIG. 7).
- a contact hole H as shown in FIG. 6 is formed in the insulating layer 9 above the second electrode 5b (step S7 in FIG. 7).
- the edge portion of the contact hole H may be formed so as to stand up from the second electrode 5b. .
- a chemical dry etching method is adopted as a method for forming the contact hole H.
- the gas is decomposed in another reaction chamber, not directly above the portion of the insulating layer 9 where the contact hole H is to be formed, and the generated radicals are transported to the portion to perform the etching process.
- the edge portion of the contact hole H can be tapered. Since the edge portion of the contact hole H is tapered, it is possible to accurately prevent the bias line 8 from being cut at the edge portion of the contact hole H.
- any technique other than chemical dry etching may be used as long as it can achieve the above-mentioned purpose. For example, if the cutting of the bias line 8 does not occur even if the plasma etching method is used, plasma is used. It is also possible to employ an etching method.
- the bias line 8 is wired on the insulating layer 9, and the bias line 8 is connected to the conversion unit 5 via the contact hole H.
- the second electrode 5b is connected (step S8 in FIG. 7).
- the bias line 8 is made of a metal wire such as aluminum.
- the bias line 8 may be wired after the surface of the insulating layer 9 is flattened by filling the concave portion of the insulating layer 9 with a resin or the like.
- the contact hole H is formed immediately above the electrode 6a of the resistance switch 6 and the main body 6b.
- the formation position of the contact hole H and the wiring of the bias line 8 are shown.
- the position is not limited to this.
- the contact hole H and the bias line 8 may be formed and wired at positions other than the above.
- the contact hole H may be provided at the end of the second electrode 5b of the conversion unit 5 or the like. It is also possible to do. It is also possible to configure the bias line 8 to be wired in a portion between the conversion units 5.
- the imaging sensor 1 is another imaging device such as a digital camera. Needless to say, the image sensor is used in a control method suitable for it.
- control means 20 (see FIG. 4) of the image sensor 1 in the radiographic image capturing apparatus 100 receives the radiation from the switching driver 10 before the radiation image capturing apparatus 100 is irradiated with radiation.
- Each resistance switch 6 is switched to a high resistance state by controlling the voltage value of the voltage applied to each second electrode 5b of each converter 5 via each bias line 8.
- each conversion unit 5 By switching the resistance switch 6 of each conversion unit 5 to a high resistance state, the irradiated radiation is converted into light by the scintillator 3, and the converted light is irradiated, whereby the i layer 5e of each conversion unit 5 is irradiated.
- the control unit 20 causes each conversion unit 5 to shift to a charge accumulation state in which charges generated in the i layer 5e of each conversion unit 5 due to radiation irradiation are accumulated in each i layer 5e. It has become.
- each conversion unit 5 performs image data read processing for reading out the charges generated in each i-layer 5e as a result of radiation irradiation as image data.
- control unit 20 controls the voltage value of the voltage applied from the switching driver 10 to each conversion unit 5 via each bias line 8 to control each resistance switch 6. Switching to the low resistance state allows each readout circuit 14 to read out image data.
- control means 20 sequentially performs this process while shifting the bias line 8 that switches the voltage value of the voltage applied from the switching driver 10, and charges are transferred from the conversion units 5 connected to the bias lines 8.
- the control means 20 sequentially discharging the signal lines 7 and sequentially reading them as image data by the respective readout circuits 14, the image data is read out from the respective converters 5.
- the resistance switch 6 mainly includes a unipolar (also referred to as non-polar) resistance switch and a bipolar resistance switch.
- a bipolar resistance switch is used as the resistance switch 6. A description will be given of the image data read processing by the control means 20 in the case of such a case.
- FIG. 13 shows that when the applied voltage V exceeds a certain threshold value of the positive voltage, the low resistance state is switched to the high resistance state, and when the applied voltage V exceeds a certain threshold value of the negative voltage, the high resistance state is changed to the low resistance state. It is a graph explaining an example of the bipolar resistance switch of the type switched to.
- the resistance value of the resistance switch 6 is not changed until the direction of the voltage V (also referred to as polarity) applied to the resistance switch 6 is reversed between positive and negative. A transition can be made between a high resistance state and a low resistance state.
- the resistance value of the resistance switch 6 transitions to a low resistance state. Further, when the resistance value of the resistance switch 6 is in a low resistance state, if the polarity of the voltage V applied to the resistance switch 6 is changed and its absolute value exceeds a predetermined voltage value Vst, the resistance of the resistance switch 6 The value transitions to a high resistance state.
- the resistance value is changed by changing the voltage value of the voltage V to be applied while changing the direction of the voltage V to be applied.
- the resistance value of the switch 6 can be varied.
- the control means 20 is configured to perform image data read processing and the like by controlling as follows.
- the resistance value of the resistance switch 6 is set to a high resistance state, and in the image data reading process, the resistance value of the resistance switch 6 is switched to a low resistance state.
- FIG. 14 shows a time such as the voltage Vb applied to the second electrode 5b of the conversion unit 5 and the voltage V applied between the electrode 6a of the resistance switch 6 and the first electrode 5a when the bipolar resistance switch 6 is used. It is a graph showing a target transition.
- each conversion unit 5 a so-called dark current (also referred to as dark charge) is normally generated due to thermal excitation by heat (temperature) of each conversion unit 5 itself, and this dark current is a high resistance. Instead of being blocked by the resistance switch 6 and flowing out to the signal line 7, it is accumulated in the main body 5 c of each converter 5. Therefore, as shown in the left end portion of FIG. 14, the voltage V of the first electrode 5a is in a state of gradually decreasing according to the amount of dark current generated.
- the control unit 20 starts reading processing of image data from each conversion unit 5. ing.
- the control means 20 reduces the voltage Vb applied to the first bias line 8a from the switching driver 10 from the reverse bias voltage Vbias so far. That is, the voltage Vb applied from the switching driver 10 to the bias line 8a is supplied from the first power supply circuit 12a from the reverse bias voltage Vbias having a predetermined voltage value supplied from the bias power supply 11 (see FIG. 4). The voltage Vb is lower than the reverse bias voltage Vbias. At this time, the voltage Vb applied to the other bias lines 8b, 8c,... Remains the reverse bias voltage Vbias.
- the resistance value of the bipolar resistance switch 6 transitions from a high resistance state to a low resistance state. To do. Therefore, the charge generated in the i layer 5e of the conversion unit 5 is released to the signal line 7 through the resistance switch 6 in a low resistance state.
- each charge flows into the corresponding readout circuit 14, As described above, the data is read out as image data by the readout circuit 14 and the like, respectively output to the storage means 21 and sequentially stored.
- the control means 20 starts the first switching driver 10 from the switching driver 10 in order to shift the resistance value of the resistance switch 6 to the high resistance state at the stage where the discharge of the electric charges from each conversion unit 5 is finished.
- the voltage Vb applied to the bias line 8a is increased at a stroke so that the voltage Vb becomes a predetermined positive voltage value.
- control means 20 has a voltage value lower than the reverse bias voltage Vbias supplied from the first power supply circuit 12a (see FIG. 4) by applying the voltage Vb applied from the switching driver 10 to the bias line 8a.
- the voltage Vb is switched to the voltage Vb having a predetermined positive voltage value supplied from the second power supply circuit 12b.
- the potential difference V between the electrode 6a of the resistance switch 6 and the first electrode 5a that is, the voltage V of the first electrode 5a is pushed up at a stretch to change to a positive voltage value and exceed a predetermined voltage value Vrs. For this reason, the resistance value of the bipolar resistance switch 6 transitions from a low resistance state to a high resistance state this time.
- the control means 20 immediately applies the switching driver 10 to the bias line 8a.
- the voltage Vb to be returned is returned to the original reverse bias voltage Vbias. That is, the control unit 20 supplies the voltage Vb applied to the bias line 8a from the switching driver 10 from the bias power supply 11 from the voltage Vb having a predetermined positive voltage value supplied from the second power supply circuit 12b.
- the reverse bias voltage Vbias having a predetermined voltage value is switched.
- the conversion units 5 connected to the bias line 8a are thus returned to the original charge accumulation state.
- the control unit 20 performs reading processing on the bias line 8b in the same manner, and reads image data from each conversion unit 5 connected to the bias line 8b. In this manner, the control unit 20 sequentially performs the image data read processing while shifting the bias line 8 for switching the voltage Vb to be applied, so that each conversion unit 5 connected to each bias line 8 ( That is, the image data is read out from all the conversion units 5).
- FIG. 15 shows an electrode 6a-first electrode 5a (that is, electrode 6c) in a unipolar resistance switch 6 of a type in which a high resistance state and a low resistance state are switched when the absolute value of the applied voltage V exceeds a threshold value. It is a graph explaining the relationship between the electric potential V between and the electric current I which flows.
- the direction (also referred to as polarity) of the voltage V applied to the resistance switch 6 is the same (ie, the applied voltage V is, for example, In a state where the voltage is a negative value), the resistance value transitions between a high resistance state and a low resistance state according to the applied voltage V.
- the voltage V to be applied is increased, and when the voltage V further increases and exceeds the threshold value Vrs on the positive voltage side, the resistance value of the resistance switch 6 transitions from the low resistance state to the high resistance state. .
- the resistance switch 6 has a resistance value in a high resistance state and a resistance value in a low resistance state from the viewpoint of the S / N ratio in the read image data. It is desirable to use one having a ratio to the value of 10 5 or more.
- each conversion unit 5 the voltage Vb applied to the second electrode 5 b of each conversion unit 5 from the switching driver 10 via each bias line 8 is read out in the same manner as described above.
- the resistance value of each resistance switch 6 is switched between a high resistance state and a low resistance state by lowering or raising in the same manner as in the above, and charges remaining in each conversion unit 5 are accurately removed. can do.
- the resistance switch 6 is used as the switch element of each conversion unit 5, for example, as illustrated in FIG.
- the structure of the conversion unit 5 can be further simplified.
- the on / off operation of the resistor switch 6, that is, a high resistance operation.
- the transition between the state and the low resistance state can be performed by varying the voltage Vb applied to the second electrode 5b of each converter 5 via the bias line 8.
- a voltage for turning on / off the TFT is applied to the image sensor 1 and the radiation image capturing apparatus 100. There is no need to provide the scanning line Ga.
- the scanning line Ga is provided in order to secure a space for providing the scanning line Ga on the substrate and to prevent a short circuit from occurring with other wirings.
- the scanning line Ga is not necessary, and it is not necessary to take the above-described measures. .
- PEP Photo Etching Process
- the resistive switches 6 and the like can be stacked by a simpler method using, for example, a shadow mask.
- the conversion unit 5 according to the present embodiment can be manufactured by a simple manufacturing process, and the conversion unit 5, the image sensor 1, and the radiation image capturing apparatus 100 according to the present embodiment are manufactured by a simpler production process. It becomes possible. For this reason, it is possible to improve the productivity of the conversion unit 5, the image sensor 1, and the radiation image capturing apparatus 100, and to obtain a beneficial effect that it is possible to improve the production yield. It becomes possible.
- the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.
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Abstract
Provided is an image sensor in which a plurality of conversion units are arrayed in a two-dimensional shape, wherein conversion units are used which include switching elements with a simpler structure than before. An image sensor (1) comprises: a plurality of conversion units (5) which are arrayed in a two-dimensional shape upon a substrate (4), further comprising first electrodes (5a) and second electrodes (5b); resistor switches (6) which are each disposed to be electrically connected to the first electrodes (5a) of each of the conversion units (5); signal lines (7) which are positioned to be connected to each of the resistor switches (6); bias lines (8) which are positioned to be connected to the second electrodes (5b) of each of the conversion units (5); a switch driver (10) to which each of the bias lines (8) is connected; read-out circuits (14) which are connected to each of the signal lines (7); and a control means (20) which controls the driving of the switch driver (10) and each of the read-out circuits (14), causing same to carry out an image data read-out process from each of the conversion units (5).
Description
本発明は、イメージセンサーおよび放射線画像撮影装置に係り、特に、複数の変換部が二次元状に配列されたイメージセンサーおよびそれを用いた放射線画像撮影装置に関する。
The present invention relates to an image sensor and a radiographic image capturing apparatus, and more particularly to an image sensor in which a plurality of conversion units are arranged two-dimensionally and a radiographic image capturing apparatus using the image sensor.
二次元状(マトリクス状)に配列された変換部で、照射された可視光等の光の光量に応じて電荷を発生させ、電気信号に変換して画像を撮影するイメージセンサーが知られている。また、そのようなイメージセンサーを利用した装置として、例えば、照射されたX線等の放射線をシンチレーター等で可視光等の他の波長の光に変換した後、変換され照射された光のエネルギーに応じてフォトダイオード等の変換部で電荷を発生させて電気信号(すなわち画像データ)に変換する放射線画像撮影装置が種々開発されている。
2. Description of the Related Art An image sensor that captures an image by generating electric charges according to the amount of light such as visible light irradiated by a conversion unit arranged in a two-dimensional form (matrix form) and converting the electric signal into an electric signal is known. . In addition, as an apparatus using such an image sensor, for example, after converting irradiated radiation such as X-rays into light of other wavelengths such as visible light with a scintillator or the like, it is converted into energy of the irradiated light. In response to this, various radiographic imaging apparatuses have been developed that generate charges in a converter such as a photodiode and convert them into electrical signals (that is, image data).
このタイプの放射線画像撮影装置はFPD(Flat Panel Detector)として知られており、従来は支持台と一体的に形成された、いわゆる専用機型として構成されていたが(例えば特許文献1参照)、近年、二次元状に配列された変換部等を筐体内に収納し、持ち運び可能とした可搬型の放射線画像撮影装置が開発され、実用化されている(例えば特許文献2、3参照)。
This type of radiographic imaging device is known as an FPD (Flat Panel Detector) and has been conventionally formed as a so-called special-purpose machine that is integrally formed with a support base (see, for example, Patent Document 1). In recent years, portable radiographic image capturing apparatuses that can accommodate two-dimensionally arranged conversion units in a housing and are portable have been developed and put into practical use (for example, see Patent Documents 2 and 3).
このようなイメージセンサー(或いは放射線画像撮影装置。以下同じ。)では、例えば図17に示すように、通常、複数の変換部Aが基板上に二次元状に配列され、各変換部Aの一方側の電極Aaに、スイッチ素子である薄膜トランジスター(Thin Film Transistor。以下、TFTという。)等を介して信号線Siが接続される。
In such an image sensor (or radiographic image capturing apparatus; the same applies hereinafter), for example, as shown in FIG. 17, usually, a plurality of conversion units A are two-dimensionally arranged on a substrate, and one of the conversion units A is arranged. A signal line Si is connected to the electrode Aa on the side through a thin film transistor (Thin-Film-Transistor, hereinafter referred to as TFT) as a switch element.
そして、TFTの開閉を制御するために、通常、TFTのゲートをオン/オフするための電圧を印加する走査線Gaが、各TFTのゲート電極Gにそれぞれ接続されるように構成される。なお、図17中のS、DはそれぞれTFTのソース電極およびドレイン電極を表す。
In order to control the opening / closing of the TFT, the scanning line Ga to which a voltage for turning on / off the TFT is normally applied is connected to the gate electrode G of each TFT. Note that S and D in FIG. 17 represent a source electrode and a drain electrode of the TFT, respectively.
また、各変換部Aの他方側の電極Abにバイアス線Bが接続されるように構成される。そして、バイアス電源Pbからバイアス線Bを介して各変換部Aにバイアス電圧が印加される。そして、通常の状態では、各変換部A内を電流が流れる方向ではなく、各変換部A内に電流が流れない方向のバイアス電圧、すなわちいわゆる逆バイアス電圧が印加される。
Further, the bias line B is connected to the electrode Ab on the other side of each conversion unit A. A bias voltage is applied to each conversion unit A from the bias power supply Pb via the bias line B. In a normal state, a bias voltage in a direction in which no current flows in each converter A, that is, a so-called reverse bias voltage, is applied instead of a direction in which current flows in each converter A.
そして、この状態で、各TFTがオフ状態とされ、イメージセンサーに光が照射されると、光の照射により各変換部A内で発生した電子と正孔が、再結合することなく、それぞれ変換部Aの対応する電極Aa、Ab側に移動する。
In this state, when each TFT is turned off and the image sensor is irradiated with light, electrons and holes generated in each conversion portion A due to light irradiation are converted without recombination. It moves to the corresponding electrode Aa, Ab side of the part A.
すなわち、発生した正孔は電位が低い側の電極(すなわち例えばバイアス線Bが接続されている電極Ab)側に移動し、発生した電子は電位が高い側の電極(すなわち例えばTFTを介して信号線Siに接続されている電極Aa)側に移動する。このようにして、各変換部Aでは、逆バイアス電圧が印加されることにより、光の照射により発生した電子や正孔がそれぞれ対応する電極Aa、Ab側に移動して分離される。
That is, the generated holes move to the electrode having the lower potential (ie, the electrode Ab to which the bias line B is connected), and the generated electrons are signaled via the electrode having the higher potential (ie, the TFT, for example). It moves to the electrode Aa) side connected to the line Si. In this manner, in each converter A, by applying a reverse bias voltage, electrons and holes generated by light irradiation move to the corresponding electrodes Aa and Ab, respectively, and are separated.
そして、この状態でTFTのゲート電極Gにオン電圧が印加されることで、電子(或いは正孔。以下まとめて電荷という。)が変換部A内から信号線Siに放出される。そして、その電荷が信号線Siを伝わって読み出し回路Croに流れ込み、読み出し回路Croで画像データに変換される。このようにして、放射線の照射により各変換部A内で発生した電荷に応じた画像データがそれぞれ読み出されるように構成される。
In this state, an ON voltage is applied to the gate electrode G of the TFT, so that electrons (or holes, hereinafter collectively referred to as charges) are emitted from the conversion part A to the signal line Si. Then, the electric charge flows through the signal line Si and flows into the readout circuit Cro, and is converted into image data by the readout circuit Cro. In this way, the image data corresponding to the electric charges generated in each conversion unit A due to the irradiation of radiation is configured to be read out.
ところで、本発明者らがイメージセンサーや放射線画像撮影装置の構成や、変換部の構成等について研究を重ねた結果、変換部をより単純な構造で構成することが可能であることが見出された。より詳しく言えば、変換部のスイッチ素子を上記のTFT等の複雑な構成を有するスイッチ素子ではなく、より単純な構造で構成することが可能であることが分かった。
By the way, as a result of repeated studies by the present inventors on the configuration of the image sensor and the radiographic imaging device, the configuration of the conversion unit, etc., it has been found that the conversion unit can be configured with a simpler structure. It was. More specifically, it has been found that the switch element of the conversion unit can be configured with a simpler structure rather than a switch element having a complicated configuration such as the above-described TFT.
そして、変換部のスイッチ素子をこのような単純な構成とすることにより、上記の従来のイメージセンサーや放射線画像撮影装置で用いられていた、TFTのゲートをオン/オフするための電圧を印加するための走査線Gaが不要になったり、変換部やイメージセンサーや放射線画像撮影装置をより簡易に生産することが可能となる等の種々の有益な効果が得られることも分かってきた。
Then, by adopting such a simple configuration for the switching element of the conversion unit, a voltage for turning on / off the TFT gate, which has been used in the above-described conventional image sensor and radiographic apparatus, is applied. It has also been found that various beneficial effects can be obtained, such as eliminating the need for the scanning line Ga, and making it possible to more easily produce the conversion unit, the image sensor, and the radiation image capturing apparatus.
本発明は、上記の問題点を鑑みてなされたものであり、複数の変換部が二次元状に配列されたイメージセンサーにおいて、構造がより単純化されたスイッチ素子を含む変換部を用いたイメージセンサーを提供し、また、それを用いた放射線画像撮影装置を提供することを目的とする。
The present invention has been made in view of the above problems, and in an image sensor in which a plurality of conversion units are arranged two-dimensionally, an image using a conversion unit including a switch element with a more simplified structure. It is an object of the present invention to provide a sensor and to provide a radiographic image capturing apparatus using the sensor.
前記の問題を解決するために、本発明のイメージセンサーは、
基板上に二次元状に配列された、第1電極および第2電極を備える複数の変換部と、
前記各変換部の第1電極とそれぞれ電気的に接続されるように設けられ、電圧印加により抵抗値が変化する各抵抗スイッチと、
二次元状に配列された前記各変換部の各列ごとに、それぞれ前記各抵抗スイッチと接続されるように配線された各信号線と、
二次元状に配列された前記各変換部の各行ごとに、それぞれ前記各変換部の第2電極と接続されるように配線され、前記各変換部に電圧を印加する各バイアス線と、
前記各バイアス線ごとに印加する電圧の電圧値を切り替える切替ドライバーと、
前記変換部から対応する前記信号線に放出された電荷を画像データに変換して読み出す、前記各信号線ごとに設けられた各読み出し回路と、
少なくとも前記切替ドライバーおよび前記各読み出し回路の動作を制御して、前記各変換部から、光の照射により前記各変換部内で発生した電荷を前記画像データとして読み出す画像データの読み出し処理を行わせる制御手段と、
を備えることを特徴とする。 In order to solve the above-described problem, the image sensor of the present invention includes:
A plurality of converters including a first electrode and a second electrode arranged two-dimensionally on a substrate;
Each resistance switch that is provided so as to be electrically connected to the first electrode of each of the conversion units, and whose resistance value changes by voltage application;
Each signal line wired so as to be connected to each of the resistance switches for each column of the conversion units arranged two-dimensionally,
For each row of each of the converters arranged in a two-dimensional manner, each bias line wired to be connected to the second electrode of each converter, and applying a voltage to each converter,
A switching driver for switching the voltage value of the voltage applied to each bias line;
Each readout circuit provided for each of the signal lines, which converts the charges discharged from the conversion unit to the corresponding signal lines into image data and reads out the image data;
Control means for controlling the operation of at least the switching driver and each readout circuit to read out the image data from the respective conversion units to read out the electric charges generated in the respective conversion units by the light irradiation as the image data. When,
It is characterized by providing.
基板上に二次元状に配列された、第1電極および第2電極を備える複数の変換部と、
前記各変換部の第1電極とそれぞれ電気的に接続されるように設けられ、電圧印加により抵抗値が変化する各抵抗スイッチと、
二次元状に配列された前記各変換部の各列ごとに、それぞれ前記各抵抗スイッチと接続されるように配線された各信号線と、
二次元状に配列された前記各変換部の各行ごとに、それぞれ前記各変換部の第2電極と接続されるように配線され、前記各変換部に電圧を印加する各バイアス線と、
前記各バイアス線ごとに印加する電圧の電圧値を切り替える切替ドライバーと、
前記変換部から対応する前記信号線に放出された電荷を画像データに変換して読み出す、前記各信号線ごとに設けられた各読み出し回路と、
少なくとも前記切替ドライバーおよび前記各読み出し回路の動作を制御して、前記各変換部から、光の照射により前記各変換部内で発生した電荷を前記画像データとして読み出す画像データの読み出し処理を行わせる制御手段と、
を備えることを特徴とする。 In order to solve the above-described problem, the image sensor of the present invention includes:
A plurality of converters including a first electrode and a second electrode arranged two-dimensionally on a substrate;
Each resistance switch that is provided so as to be electrically connected to the first electrode of each of the conversion units, and whose resistance value changes by voltage application;
Each signal line wired so as to be connected to each of the resistance switches for each column of the conversion units arranged two-dimensionally,
For each row of each of the converters arranged in a two-dimensional manner, each bias line wired to be connected to the second electrode of each converter, and applying a voltage to each converter,
A switching driver for switching the voltage value of the voltage applied to each bias line;
Each readout circuit provided for each of the signal lines, which converts the charges discharged from the conversion unit to the corresponding signal lines into image data and reads out the image data;
Control means for controlling the operation of at least the switching driver and each readout circuit to read out the image data from the respective conversion units to read out the electric charges generated in the respective conversion units by the light irradiation as the image data. When,
It is characterized by providing.
また、本発明の放射線画像撮影装置は、
上記の本発明のイメージセンサーと、
放射線が照射されると、放射線を光に変換して前記各変換部に出力するシンチレーターと、
を備えることを特徴とする。 Moreover, the radiographic imaging device of the present invention is
The image sensor of the present invention,
When irradiated with radiation, a scintillator that converts the radiation into light and outputs the light to each of the conversion units;
It is characterized by providing.
上記の本発明のイメージセンサーと、
放射線が照射されると、放射線を光に変換して前記各変換部に出力するシンチレーターと、
を備えることを特徴とする。 Moreover, the radiographic imaging device of the present invention is
The image sensor of the present invention,
When irradiated with radiation, a scintillator that converts the radiation into light and outputs the light to each of the conversion units;
It is characterized by providing.
本発明のような方式のイメージセンサーや放射線画像撮影装置によれば、各変換部のスイッチ素子として抵抗スイッチを用いるように構成したため、例えば後述する図6等に示すように、変換部の構造をより単純化することが可能となる。
According to the image sensor and the radiographic imaging apparatus of the system of the present invention, since the resistance switch is used as the switch element of each conversion unit, for example, as shown in FIG. It becomes possible to further simplify.
また、このように各変換部のスイッチ素子として抵抗スイッチを用いるように構成すると、抵抗スイッチのオン/オフ動作、すなわち高抵抗の状態と低抵抗の状態との間の遷移を、バイアス線を介して各変換部に印加する電圧を可変させることで行うことが可能となる。そして、例えば図17に示した従来の変換部Aのようにスイッチ素子としてTFTを用いないため、イメージセンサーや放射線画像撮影装置に、TFTにオン/オフ動作をさせるための電圧を印加する走査線Gaを設ける必要がなくなる。
In addition, when the resistance switch is used as the switching element of each conversion unit in this way, the on / off operation of the resistance switch, that is, the transition between the high resistance state and the low resistance state is performed via the bias line. Thus, it is possible to change the voltage applied to each converter. Further, for example, since a TFT is not used as a switching element as in the conventional conversion unit A shown in FIG. 17, a scanning line for applying a voltage for turning on / off the TFT to an image sensor or a radiographic imaging device. There is no need to provide Ga.
そして、走査線Gaを設けない分だけ、イメージセンサーや放射線画像撮影装置の基板上での変換部や抵抗スイッチ、信号線、バイアス線等のレイアウトの自由度が拡大する等の有益な効果が得られる。また、TFTを形成するために複雑な工程を繰り返し行うことが必要であったが、抵抗スイッチは、例えばシャドーマスクを用いた、より簡単な方法で行うことができる。
In addition, since the scanning line Ga is not provided, a beneficial effect such as an increase in the degree of freedom of layout of the conversion unit, the resistance switch, the signal line, the bias line, etc. on the substrate of the image sensor or the radiographic imaging apparatus is obtained. It is done. Further, it has been necessary to repeatedly perform a complicated process for forming a TFT, but the resistance switch can be performed by a simpler method using a shadow mask, for example.
そのため、変換部を簡単な製造プロセスにより製造することが可能となり、変換部やイメージセンサー、放射線画像撮影装置をより簡易な生産工程で製造することが可能となる。また、そのため、変換部やイメージセンサー、放射線画像撮影装置の生産性を向上させることが可能となるとともに、生産における歩留まりの向上を図ることが可能となるといった有益な効果を得ることも可能となる。
Therefore, the conversion unit can be manufactured by a simple manufacturing process, and the conversion unit, the image sensor, and the radiographic imaging device can be manufactured by a simpler production process. For this reason, it is possible to improve the productivity of the conversion unit, the image sensor, and the radiation image capturing apparatus, and it is also possible to obtain a beneficial effect that the yield in production can be improved. .
以下、本発明に係るイメージセンサーや放射線画像撮影装置の実施の形態について、図面を参照して説明する。
Hereinafter, embodiments of an image sensor and a radiographic imaging apparatus according to the present invention will be described with reference to the drawings.
なお、以下では、イメージセンサーを放射線画像撮影装置に適用した構成例について説明するが、この他にも、例えばイメージセンサーをデジタルカメラ等の他の撮影機器のイメージセンサーとして用いるように構成することも可能であり、このように構成した場合にも本発明が適用される。
In the following, a configuration example in which an image sensor is applied to a radiographic imaging device will be described. However, for example, the image sensor may be configured to be used as an image sensor for other imaging devices such as a digital camera. It is possible, and the present invention is also applied to such a configuration.
また、以下では、放射線画像撮影装置として、いわゆる可搬型の放射線画像撮影装置について説明するが、例えば支持台等と一体的に形成された専用機型(固定型等ともいう。)の放射線画像撮影装置に対しても適用することが可能である。
In the following, a so-called portable radiographic imaging apparatus will be described as the radiographic imaging apparatus. However, for example, a radiographic imaging of a dedicated machine type (also referred to as a fixed type) integrally formed with a support base or the like. The present invention can be applied to an apparatus.
[放射線画像撮影装置としての構成]
以下、まず、放射線画像撮影装置としての構成について説明する。図1は、本実施形態に係る放射線画像撮影装置の外観を示す斜視図であり、図2は、図1のX-X線に沿う断面図である。放射線画像撮影装置100は、図1や図2に示すように、筐体2内にシンチレーター3や基板4等で構成されるセンサーパネルSPが収納されている。 [Configuration as a radiographic imaging device]
Hereinafter, a configuration as a radiographic imaging device will be described first. FIG. 1 is a perspective view showing an appearance of a radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line XX of FIG. As shown in FIGS. 1 and 2, the radiationimage capturing apparatus 100 includes a housing 2 in which a sensor panel SP including a scintillator 3 and a substrate 4 is accommodated.
以下、まず、放射線画像撮影装置としての構成について説明する。図1は、本実施形態に係る放射線画像撮影装置の外観を示す斜視図であり、図2は、図1のX-X線に沿う断面図である。放射線画像撮影装置100は、図1や図2に示すように、筐体2内にシンチレーター3や基板4等で構成されるセンサーパネルSPが収納されている。 [Configuration as a radiographic imaging device]
Hereinafter, a configuration as a radiographic imaging device will be described first. FIG. 1 is a perspective view showing an appearance of a radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line XX of FIG. As shown in FIGS. 1 and 2, the radiation
なお、以下の説明においては、上下方向は、図1や図2中における上下方向に即して表す(すなわち図中上側を「上」や「上方」等と表す。)。
In the following description, the up and down direction is represented in accordance with the up and down direction in FIGS. 1 and 2 (that is, the upper side in the figure is represented as “up” or “up”).
本実施形態では、筐体2は、カーボン板やプラスチック等の材料で形成され、放射線入射面Rを有する筐体本体部2Aの両側の開口部が、蓋部材2B、2Cで閉塞されて形成されている。また、筐体2の一方側の蓋部材2Bには、電源スイッチ37や切替スイッチ38、コネクター39、バッテリー状態や放射線画像撮影装置1の稼働状態等を表示するLED等で構成されたインジケーター40等が配置されている。
In the present embodiment, the housing 2 is formed of a material such as a carbon plate or plastic, and the openings on both sides of the housing body 2A having the radiation incident surface R are closed by the lid members 2B and 2C. ing. Further, the lid member 2B on one side of the housing 2 has a power switch 37, a changeover switch 38, a connector 39, an indicator 40 composed of an LED or the like for displaying a battery state, an operating state of the radiographic imaging apparatus 1, and the like. Is arranged.
本実施形態では、例えば図3に示すように、コネクター39に、ケーブルCaの先端に設けられたコネクターCが接続されることにより外部装置との間でケーブルCaを介して信号やデータ等を送受信できるようになっている。また、図示を省略するが、本実施形態では、筐体2の反対側の蓋部材2Cに、アンテナ装置41(後述する図4参照)が設けられており、アンテナ装置41を介して外部装置と無線方式で信号やデータ等の送受信を行うこともできるようになっている。
In the present embodiment, for example, as shown in FIG. 3, a connector C provided at the tip of the cable Ca is connected to the connector 39, so that signals and data are transmitted / received to / from an external device via the cable Ca. It can be done. Although not shown, in the present embodiment, an antenna device 41 (see FIG. 4 described later) is provided on the lid member 2C on the opposite side of the housing 2, and an external device is connected via the antenna device 41. It is also possible to transmit and receive signals and data in a wireless manner.
図2に示すように、筐体2の内部には、基板4の下方側に図示しない鉛の薄板等を介して基台31が配置され、基台31には、電子部品32等が配設されたPCB基板33やバッテリー22等が取り付けられている。また、基板4やシンチレーター3の放射線入射面Rには、それらを保護するためのガラス基板34が配設されている。また、本実施形態では、センサーパネルSPと筐体2の側面との間に緩衝材35が設けられている。
As shown in FIG. 2, a base 31 is disposed inside the housing 2 via a lead thin plate (not shown) on the lower side of the substrate 4, and an electronic component 32 and the like are disposed on the base 31. The PCB substrate 33, the battery 22 and the like are attached. Further, a glass substrate 34 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed. In the present embodiment, the buffer material 35 is provided between the sensor panel SP and the side surface of the housing 2.
シンチレーター3は、基板4の後述する検出部Pに対向する位置に設けられるようになっている。本実施形態では、シンチレーター3は、例えば、蛍光体を主成分とし、放射線の入射を受けると300~800nmの波長の光、すなわち可視光を中心とした電磁波に変換して出力するものが用いられる。
The scintillator 3 is provided at a position facing the detection unit P, which will be described later, on the substrate 4. In the present embodiment, the scintillator 3 is, for example, one that has a phosphor as a main component and converts it into light having a wavelength of 300 to 800 nm, that is, an electromagnetic wave centered on visible light when it receives radiation, and outputs it. .
また、本実施形態では、基板4は、ガラス基板で構成されており、基板4のシンチレーター3に対向する側の面4a上には、後述する複数の変換部5や複数の信号線7、複数のバイアス線8等が設けられている。
Moreover, in this embodiment, the board | substrate 4 is comprised with the glass substrate, and on the surface 4a of the side facing the scintillator 3 of the board | substrate 4, the several conversion part 5 mentioned later, the several signal wire | line 7, and several Bias line 8 and the like are provided.
[イメージセンサーの構成]
以下、イメージセンサー1の回路構成について説明する。図4は本実施形態に係るイメージセンサー1の等価回路を表すブロック図である。なお、図4では、放射線画像撮影装置100で用いられるアンテナ装置41や後述する相関二重サンプリング回路16(図中では「CDS」と記載されている。)等も含めて示されている。 [Image sensor configuration]
Hereinafter, the circuit configuration of theimage sensor 1 will be described. FIG. 4 is a block diagram showing an equivalent circuit of the image sensor 1 according to the present embodiment. In FIG. 4, an antenna device 41 used in the radiographic image capturing apparatus 100 and a correlated double sampling circuit 16 (described as “CDS” in the drawing), which will be described later, are also shown.
以下、イメージセンサー1の回路構成について説明する。図4は本実施形態に係るイメージセンサー1の等価回路を表すブロック図である。なお、図4では、放射線画像撮影装置100で用いられるアンテナ装置41や後述する相関二重サンプリング回路16(図中では「CDS」と記載されている。)等も含めて示されている。 [Image sensor configuration]
Hereinafter, the circuit configuration of the
イメージセンサー1の基板4(図2参照)上には、図4に示すように、複数の変換部5が二次元状(マトリクス状)に配列されている。本実施形態では、変換部5は、放射線画像撮影装置100の筐体2の放射線入射面R(図1等参照)から放射線が入射し、シンチレーター3(図2参照)で放射線から変換された可視光等の光が照射されると、後述するi層5e(後述する図6参照)で電子正孔対を発生させる。
On the substrate 4 (see FIG. 2) of the image sensor 1, as shown in FIG. 4, a plurality of converters 5 are arranged in a two-dimensional form (matrix form). In the present embodiment, the conversion unit 5 has a radiation incident from a radiation incident surface R (see FIG. 1 and the like) of the housing 2 of the radiographic imaging device 100, and is converted into visible light from the scintillator 3 (see FIG. 2). When light such as light is irradiated, electron-hole pairs are generated in an i layer 5e described later (see FIG. 6 described later).
変換部5は、このようにして、照射された放射線(本実施形態ではシンチレーター3で放射線から変換された光)を電荷に変換するようになっている。そして、複数の変換部5が二次元状に配列された領域(すなわち図4に一点鎖線で示される領域)がイメージセンサー1の検出部Pとされている。
In this way, the conversion unit 5 converts the irradiated radiation (in this embodiment, light converted from the radiation by the scintillator 3) into electric charges. A region in which the plurality of conversion units 5 are two-dimensionally arranged (that is, a region indicated by a one-dot chain line in FIG. 4) is the detection unit P of the image sensor 1.
本実施形態では、変換部5としてフォトダイオードが用いられているが、この他にも例えばフォトトランジスター等を用いることも可能である。
In the present embodiment, a photodiode is used as the conversion unit 5, but other than this, for example, a phototransistor or the like can also be used.
そして、図4に示すように、各変換部5の第1電極5aには、電圧印加により抵抗値が変化する各抵抗スイッチ6がそれぞれ電気的に接続されている。なお、本実施形態に係る抵抗スイッチ6を含む変換部5の具体的な構成等については、後で説明する。
As shown in FIG. 4, each resistance switch 6 whose resistance value is changed by voltage application is electrically connected to the first electrode 5 a of each converter 5. A specific configuration of the conversion unit 5 including the resistance switch 6 according to this embodiment will be described later.
本実施形態では、二次元状に配列された各変換部5の各列ごとに、それぞれ各抵抗スイッチ6と接続されるように複数の信号線7が配線されている。そして、抵抗スイッチ6は、抵抗値が高抵抗の状態では、各変換部5内に電荷を蓄積させ、抵抗値が低抵抗の状態とされると、各変換部5内に蓄積された電荷を、抵抗スイッチ6を介して信号線7に放出させるようになっている。
In this embodiment, a plurality of signal lines 7 are wired so as to be connected to the respective resistance switches 6 for each column of the respective converters 5 arranged in a two-dimensional manner. The resistance switch 6 accumulates electric charge in each conversion unit 5 when the resistance value is high resistance. When the resistance value is set to a low resistance state, the resistance switch 6 stores the electric charge accumulated in each conversion unit 5. The signal line 7 is emitted through the resistance switch 6.
また、各変換部5の第2電極5bには、それぞれバイアス線8が接続されている。そして、バイアス線8は、二次元状に配列された各変換部5の各行ごとに1本ずつ配線されており、また、各バイアス線8は、切替ドライバー10の各端子にそれぞれ接続されている。
Further, a bias line 8 is connected to each of the second electrodes 5b of each conversion unit 5. One bias line 8 is wired for each row of each conversion unit 5 arranged two-dimensionally, and each bias line 8 is connected to each terminal of the switching driver 10. .
切替ドライバー10には、バイアス電源11が接続されており、切替ドライバー10は、通常の場合すなわち後述する画像データの読み出し処理以外の場合には、バイアス電源11から供給される所定の電圧値の電圧Vbias、すなわち前述した逆バイアス電圧Vbiasを、各バイアス線8にそれぞれ印加するようになっている。そのため、通常の状態では、各バイアス線8や各接続線8を介して変換部5の第2電極5bに逆バイアス電圧Vbiasが印加された状態になる。
A bias power supply 11 is connected to the switching driver 10. The switching driver 10 is a voltage having a predetermined voltage value supplied from the bias power supply 11 in a normal case, that is, in a case other than the image data reading process described later. Vbias, that is, the above-described reverse bias voltage Vbias is applied to each bias line 8. Therefore, in a normal state, the reverse bias voltage Vbias is applied to the second electrode 5b of the conversion unit 5 via each bias line 8 and each connection line 8.
また、本実施形態では、切替ドライバー10とバイアス電源11との間には、バイアス電源11から出力された電圧の電圧値をそれぞれ別の電圧値に変換して切替ドライバー10に供給する第1電源回路12aおよび第2電源回路12bがそれぞれ接続されている。
In the present embodiment, the first power source that supplies the switching driver 10 with the voltage value of the voltage output from the bias power source 11 converted into a different voltage value between the switching driver 10 and the bias power source 11. The circuit 12a and the second power supply circuit 12b are connected to each other.
そして、前述したように、バイアス電源11は切替ドライバー10に対して所定の電圧値の逆バイアス電圧Vbiasを供給し、後述するように、第1電源回路12aは、逆バイアス電圧Vbiasより低い電圧値の電圧を切替ドライバー10に供給し、第2電源回路12bは、逆バイアス電圧Vbiasよりも高い電圧値の電圧を切替ドライバー10に供給するようになっている。
As described above, the bias power supply 11 supplies the switching driver 10 with the reverse bias voltage Vbias having a predetermined voltage value. As described later, the first power supply circuit 12a has a voltage value lower than the reverse bias voltage Vbias. The second power supply circuit 12b supplies a voltage having a voltage value higher than the reverse bias voltage Vbias to the switching driver 10.
そして、切替ドライバー10は、後述する画像データの読み出し処理の際に、各バイアス線8に印加する電圧Vbを、バイアス電源11から供給される逆バイアス電圧Vbiasと、第1電源回路12aから供給されるそれより低い電圧値の電圧と、第2電源回路12bから供給されるそれよりも高い電圧値の電圧との間で切り替えて、抵抗スイッチ6の抵抗値を可変させるようになっているが、この点については後で説明する。
The switching driver 10 is supplied with a voltage Vb to be applied to each bias line 8 from the bias power supply 11 and a reverse bias voltage Vbias supplied from the bias power supply 11 and the first power supply circuit 12a in a later-described image data read process. The resistance value of the resistance switch 6 is varied by switching between a voltage having a lower voltage value and a voltage having a voltage value higher than that supplied from the second power supply circuit 12b. This point will be described later.
一方、図4に示すように、各信号線7は、読み出しIC13内に内蔵された各読み出し回路14にそれぞれ接続されている。本実施形態では、読み出し回路14は、増幅回路15と相関二重サンプリング回路16等で構成されている。読み出しIC13内には、さらに、アナログマルチプレクサー17と、A/D変換器18とが設けられている。
On the other hand, as shown in FIG. 4, each signal line 7 is connected to each readout circuit 14 built in the readout IC 13. In the present embodiment, the readout circuit 14 includes an amplifier circuit 15 and a correlated double sampling circuit 16. An analog multiplexer 17 and an A / D converter 18 are further provided in the reading IC 13.
なお、図4中では、相関二重サンプリング回路16はCDSと表記されている。また、本実施形態では、各読み出し回路13側から各信号線7に対して例えば0[V]等の基準電位V0が印加されるようになっている。
In FIG. 4, the correlated double sampling circuit 16 is denoted as CDS. In the present embodiment, a reference potential V 0 such as 0 [V] is applied to each signal line 7 from each readout circuit 13 side.
そして、本実施形態では、各変換部5からの画像データの読み出し処理の際に、後述するように低抵抗の状態とされた抵抗スイッチ6を介して各変換部5から電荷が信号線7に放出されると、増幅回路15は、放出された電荷量に応じた電圧値を出力するようになっている。
In the present embodiment, when the image data is read from each conversion unit 5, the electric charge is transferred from each conversion unit 5 to the signal line 7 via a resistance switch 6 that is in a low resistance state as will be described later. When discharged, the amplifier circuit 15 outputs a voltage value corresponding to the amount of discharged charges.
そして、増幅回路15の出力側に設けられた相関二重サンプリング回路(CDS)16は、各変換部5から電荷が放出される前に増幅回路15から出力されている電圧値Vinを、各変換部5から電荷が放出された後に増幅回路15から出力されている電圧値Vfiから減算し、それらの電圧値の差分Vfi-Vinをアナログ値の画像データとして下流側に出力するようになっている。
Then, the correlated double sampling circuit (CDS) 16 provided on the output side of the amplifier circuit 15 converts the voltage value Vin output from the amplifier circuit 15 before each charge is discharged from each converter 5 into each converter. After the electric charge is discharged from the unit 5, the voltage value Vfi output from the amplifier circuit 15 is subtracted, and a difference Vfi−Vin between these voltage values is output downstream as analog value image data. .
そして、出力されたアナログ値の画像データは、アナログマルチプレクサー17を介して順次A/D変換器18に送信され、A/D変換器18で順次デジタル値の画像データに変換されて記憶手段21に出力されて順次保存されるようになっている。
The output analog value image data is sequentially transmitted to the A / D converter 18 via the analog multiplexer 17, and is sequentially converted into digital value image data by the A / D converter 18. Are output and stored sequentially.
なお、本実施形態では、上記のように、イメージセンサー1が放射線画像撮影装置100に用いられており、放射線画像撮影装置100では、通常、増幅回路15から出力される電圧値(すなわち信号値)が小さいため、相関二重サンプリング回路15が用いられているが、イメージセンサー1を他の撮影装置に用いる場合には、ノイズ信号に比べて信号値が十分大きい場合もある。このような場合には、必ずしも相関二重サンプリング回路15等を用いる必要はない。
In the present embodiment, as described above, the image sensor 1 is used in the radiographic image capturing apparatus 100. In the radiographic image capturing apparatus 100, a voltage value (that is, a signal value) normally output from the amplifier circuit 15 is used. Is small, the correlated double sampling circuit 15 is used. However, when the image sensor 1 is used for another photographing apparatus, the signal value may be sufficiently larger than the noise signal. In such a case, it is not always necessary to use the correlated double sampling circuit 15 or the like.
制御手段20は、図示しないCPU(Central Processing Unit)やROM(Read Only Memory)、RAM(Random Access Memory)、入出力インターフェース等がバスに接続されたコンピューターや、FPGA(Field Programmable Gate Array)等により構成されている。専用の制御回路で構成されていてもよい。
The control means 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a RAM (Random Access Memory), an input / output interface connected to the bus, an FPGA (Field Programmable Gate Array), etc. It is configured. It may be configured by a dedicated control circuit.
そして、制御手段20は、イメージセンサー1の各部材の動作等を制御するようになっており、例えば切替ドライバー10やバイアス電源11、第1電源回路12a、第2電源回路12b、読み出し回路14等の動作を制御して、上記のように、各変換部5から電荷を放出させて画像データとして読み出す画像データの読み出し処理を行わせる等の制御を行うようになっている。なお、画像データの読み出し処理における具体的な制御の仕方については後で説明する。
The control means 20 controls the operation of each member of the image sensor 1. For example, the switching driver 10, the bias power supply 11, the first power supply circuit 12 a, the second power supply circuit 12 b, the readout circuit 14, etc. As described above, control is performed such that image data is read out as image data by discharging electric charges from the respective converters 5 as described above. A specific control method in the image data reading process will be described later.
また、図4に示すように、制御手段20には、SRAM(Static RAM)やSDRAM(Synchronous DRAM)等で構成される記憶手段21や、各機能部に電力を供給するためのバッテリー22が接続されている。また、バッテリー22には、図示しない充電装置からバッテリー22に電力を供給してバッテリー22を充電する際の接続端子23が取り付けられている。また、本実施形態では、制御手段20には、前述した放射線画像撮影装置100のアンテナ装置41等が接続されている。
As shown in FIG. 4, the control means 20 is connected with a storage means 21 composed of SRAM (Static RAM), SDRAM (Synchronous DRAM) or the like, and a battery 22 for supplying power to each functional unit. Has been. In addition, a connection terminal 23 for charging the battery 22 by supplying power to the battery 22 from a charging device (not shown) is attached to the battery 22. In the present embodiment, the control unit 20 is connected to the antenna device 41 of the radiation image capturing apparatus 100 described above.
次に、本実施形態に係るイメージセンサー1における抵抗スイッチ6を含む変換部5の具体的な構成等について説明する。図5は、本実施形態に係る抵抗スイッチを含む変換部の拡大平面図であり、図6は、図5のY-Y線に沿う、1つの変換部の断面図である。
Next, a specific configuration and the like of the conversion unit 5 including the resistance switch 6 in the image sensor 1 according to the present embodiment will be described. FIG. 5 is an enlarged plan view of the conversion unit including the resistance switch according to the present embodiment, and FIG. 6 is a cross-sectional view of one conversion unit along line YY in FIG.
なお、以下の説明においては、上下方向は、変換部5の各構成部分を表した図6中における上下方向に即して表し(すなわち図中上側を「上」や「上方」等と表し)、左右方向は、図5や図6中における左右方向に即して表すものとする。
In the following description, the up and down direction is represented in accordance with the up and down direction in FIG. 6 representing each component of the conversion unit 5 (that is, the upper side in the figure is represented as “up”, “up”, etc.). The left-right direction is expressed in accordance with the left-right direction in FIGS.
また、図5や図6では各構成部分が見易くなるように記載されており、各構成部分の相対的な大きさや位置関係、間隔、厚み等は必ずしも現実の構成を反映していない。特に、図5では、各変換部5間を広く開けるように記載されているが、実際には、各変換部5間の間隔をできるだけ狭くして、各変換部5の開口率を向上させるように構成される。
Also, in FIG. 5 and FIG. 6, each component is described so that it can be easily seen, and the relative size, positional relationship, interval, thickness, etc. of each component do not necessarily reflect the actual configuration. In particular, in FIG. 5, it is described that the spaces between the respective conversion units 5 are widened, but actually, the interval between the respective conversion units 5 is made as narrow as possible to improve the aperture ratio of each conversion unit 5. Configured.
前述したように、本実施形態では、各変換部5は第1電極5aと第2電極5bとを備え、変換部5の第2電極5bはそれぞれバイアス線8に接続されている。また、変換部5の第1電極5aにはそれぞれ抵抗スイッチ6が電気的に接続されており、二次元状に配列された各変換部5の各列ごとに各抵抗スイッチ6がそれぞれ各信号線7に接続されている。
As described above, in this embodiment, each conversion unit 5 includes the first electrode 5a and the second electrode 5b, and the second electrode 5b of the conversion unit 5 is connected to the bias line 8, respectively. In addition, a resistance switch 6 is electrically connected to each first electrode 5a of the conversion unit 5, and each resistance switch 6 is connected to each signal line for each column of each conversion unit 5 arranged two-dimensionally. 7 is connected.
そして、本実施形態の変換部5では、変換部5の第1電極5aと、抵抗スイッチ6の一方の電極6cとが共通の電極とされている。すなわち、第1電極5aが、変換部5の第1電極5aとして機能すると同時に、抵抗スイッチ6の一方の電極6cとしても機能するように構成されている。
And in the conversion part 5 of this embodiment, the 1st electrode 5a of the conversion part 5 and the one electrode 6c of the resistance switch 6 are made into the common electrode. That is, the first electrode 5 a functions as the first electrode 5 a of the conversion unit 5 and at the same time functions as one electrode 6 c of the resistance switch 6.
そして、本実施形態の変換部5では、このように、第1電極5aを抵抗スイッチ6と共通の電極とすることにより、抵抗スイッチ6が、変換部5の第1電極5aと電気的に接続されるようになっている。
And in the conversion part 5 of this embodiment, the resistance switch 6 is electrically connected with the 1st electrode 5a of the conversion part 5 by making the 1st electrode 5a into a common electrode with the resistance switch 6 in this way. It has come to be.
また、図示を省略するが、この他にも、例えば、抵抗スイッチ6の後述する本体部6b上に、抵抗スイッチ6の一方の電極6cを変換部5の第1電極5とは別体の電極として設け、さらにその上方に変換部5の第1電極5aを積層する等して、抵抗スイッチ6の電極と変換部5の第1電極5aとを直接接続するように構成することも可能である。
In addition, although not shown, for example, one electrode 6c of the resistance switch 6 is separated from the first electrode 5 of the conversion unit 5 on a body portion 6b described later of the resistance switch 6, for example. The electrode of the resistance switch 6 and the first electrode 5a of the conversion unit 5 can be directly connected by, for example, stacking the first electrode 5a of the conversion unit 5 thereon. .
さらに、例えば、抵抗スイッチ6を基板4上の適宜の位置に形成し、抵抗スイッチ6の一方の電極6cと、変換部5の第1電極5aとを導線等で接続するようにして変換部5を構成することも可能である。これらのように構成しても、抵抗スイッチ6と、変換部5の第1電極5aとを電気的に接続することが可能である。
Furthermore, for example, the resistance switch 6 is formed at an appropriate position on the substrate 4, and the conversion unit 5 is configured such that one electrode 6 c of the resistance switch 6 and the first electrode 5 a of the conversion unit 5 are connected by a conductive wire or the like. It is also possible to configure. Even with such a configuration, it is possible to electrically connect the resistance switch 6 and the first electrode 5a of the conversion unit 5.
以下、本実施形態に係るイメージセンサー1における抵抗スイッチ6を含む変換部5の具体的な構成等について、より具体的に説明するために、その製造プロセスを示しながら説明する。図7は、抵抗スイッチを含む変換部の製造プロセスにおける各工程を表すフローチャートである。
Hereinafter, in order to more specifically describe the specific configuration of the conversion unit 5 including the resistance switch 6 in the image sensor 1 according to the present embodiment, the manufacturing process will be described. FIG. 7 is a flowchart showing each step in the manufacturing process of the conversion unit including the resistance switch.
まず、図8Aに示すように、基板4上に、アルミニウム等の金属線からなる信号線7を予め配設しておき、図8Bに示すように、基板4と信号線7上に、抵抗スイッチ6の電極6aが積層される(図6のステップS1)。
First, as shown in FIG. 8A, a signal line 7 made of a metal wire such as aluminum is arranged in advance on the substrate 4, and a resistance switch is placed on the substrate 4 and the signal line 7 as shown in FIG. 8B. 6 electrodes 6a are stacked (step S1 in FIG. 6).
本実施形態では、抵抗スイッチ6の電極6aはTiN(窒化チタン)で構成されている。また、本実施形態では、電極6aは、図5に示すように、信号線7に接続される部分の近傍に凹部が設けられるようになっている。
In this embodiment, the electrode 6a of the resistance switch 6 is made of TiN (titanium nitride). In the present embodiment, the electrode 6a is provided with a recess in the vicinity of the portion connected to the signal line 7, as shown in FIG.
後述する抵抗スイッチ6の抵抗値は、種々の要素によって決まるが、その中の1つの要素として、図9Aに示すように、抵抗スイッチ6の本体部6b(図9A、図9Bでは図示省略。図5等参照)を上下から挟む電極6aと電極6c(すなわち本実施形態では第1電極5a。以下同じ。)との本体部6bを介した接合面積に依存して変化する場合がある。
The resistance value of the resistance switch 6 to be described later is determined by various elements, and as one of the elements, as shown in FIG. 9A, the main body 6b of the resistance switch 6 (not shown in FIGS. 9A and 9B). 5 may be changed depending on the bonding area of the electrode 6a and the electrode 6c sandwiched from above and below (that is, the first electrode 5a in the present embodiment; the same shall apply hereinafter) through the main body 6b.
このような場合、製造プロセスにおいて、抵抗スイッチ6の電極6aと電極6cとの位置合わせを的確に行って、電極6aと電極6cとの相対的な配置を精密に行うことが必要となるが、シャドーマスクを使う成膜工程など、実際の製造プロセスにおいては、位置合わせ等の精度が必ずしも良くない場合がある。すなわち、実際のプロセスでは、電極6aに対して電極6cの位置が、設計上の位置からずれる場合があり得る。
In such a case, in the manufacturing process, it is necessary to accurately align the electrodes 6a and 6c of the resistance switch 6 and to accurately perform the relative arrangement of the electrodes 6a and 6c. In an actual manufacturing process such as a film forming process using a shadow mask, the accuracy of alignment or the like may not always be good. That is, in the actual process, the position of the electrode 6c may be shifted from the design position with respect to the electrode 6a.
しかし、図9Aに示す本実施形態のように、抵抗スイッチ6の電極6aに、信号線7に接続される部分と、抵抗スイッチ6の本体部6bを介して電極6cに接合される部分との間に、凹部Mを設けると、上方に積層される電極6cの位置が左右方向(図中の矢印参照)にずれても、抵抗スイッチ6の電極6aと電極6cとの接合部分の1辺の長さaは変化せず、接合面積はほぼa×bとなる。
However, as in the present embodiment shown in FIG. 9A, the electrode 6a of the resistance switch 6 has a portion connected to the signal line 7 and a portion joined to the electrode 6c via the body portion 6b of the resistance switch 6. If a recess M is provided between them, even if the position of the electrode 6c stacked above is shifted in the left-right direction (see the arrow in the figure), one side of the joint portion between the electrode 6a and the electrode 6c of the resistance switch 6 is provided. The length a does not change, and the junction area is approximately a × b.
この場合、上方に積層される電極6cの位置が左右方向にずれると、図9Aに斜線を付して示す部分の面積が増減するため接合面積が増減するが、その増減はわずかであり、上方に積層される電極6cの位置が左右方向にずれても、抵抗スイッチ6の電極6aと電極6cとの本体部6bを介した接合面積はほぼa×bとなり、ほとんど変化しない。そして、実際上、接合面積をa×bとすることが可能となる。
In this case, if the position of the electrode 6c laminated on the upper side is shifted in the left-right direction, the area of the portion shown by hatching in FIG. 9A increases or decreases, so that the bonding area increases or decreases, but the increase or decrease is slight. Even if the position of the electrode 6c laminated on the right and left is shifted in the left-right direction, the joining area of the electrode 6a and the electrode 6c of the resistance switch 6 through the main body 6b is substantially a × b, and hardly changes. In practice, the junction area can be a × b.
本実施形態では、このように、抵抗スイッチ6の電極6aを、図9Aに示したような凹部Mを設けた状態で積層することにより、電極6aや抵抗スイッチ6の本体部6bの上方に積層される電極6cの位置がずれたとしても、抵抗スイッチ6の本体部6bを介した電極6aと電極6cとの接合面積がほぼa×bのまま変化しないようにすることが可能となる。
In the present embodiment, the electrode 6a of the resistance switch 6 is thus stacked with the recess M as shown in FIG. 9A, so that the electrode 6a and the body portion 6b of the resistance switch 6 are stacked. Even if the position of the electrode 6c is shifted, it is possible to keep the junction area between the electrode 6a and the electrode 6c through the main body 6b of the resistance switch 6 from approximately a × b.
そのため、抵抗スイッチ6の抵抗値が電極6aと電極6cとの本体部6bを介した接合面積に依存して変化する場合に、抵抗スイッチ6の電極6aと電極6cとの位置合わせを精密に行うことが難しい場合であっても、接合面積の変化による影響を最小限に抑え、抵抗スイッチ6の抵抗値が設計上の抵抗値からずれることを的確に防止することが可能となる。
Therefore, when the resistance value of the resistance switch 6 changes depending on the junction area of the electrode 6a and the electrode 6c via the main body 6b, the alignment of the electrode 6a and the electrode 6c of the resistance switch 6 is performed precisely. Even if this is difficult, it is possible to minimize the influence of the change in the junction area and accurately prevent the resistance value of the resistance switch 6 from deviating from the designed resistance value.
なお、抵抗スイッチ6の電極6aと電極6cとの接合面積が多少ずれて抵抗スイッチ6の抵抗値が設定値から多少ずれてもさほど影響がない場合には、図9Bに示すように、抵抗スイッチ6の電極6aに凹部を設けず、電極6aを例えば矩形状に形成することも可能である。
If the junction area between the electrode 6a and the electrode 6c of the resistance switch 6 is slightly deviated and the resistance value of the resistance switch 6 is slightly deviated from the set value, as shown in FIG. 9B, the resistance switch It is also possible to form the electrode 6a in a rectangular shape, for example, without providing a recess in the six electrodes 6a.
一方、後述するように、抵抗スイッチ6の電極6aの上方に抵抗スイッチ6の本体部6bが積層されるが(図6参照)、その際、例えば図10に示すように、電極6aのエッジ部分が基板4や信号線7から切り立った状態(すなわちテーパが設けられていない状態)になっていると、その上方に積層される抵抗スイッチ6の本体部6bが、電極6aのエッジ部分に対応する部分(図中の矢印参照)で段切れを生じてしまう場合がある。
On the other hand, as will be described later, the main body portion 6b of the resistance switch 6 is laminated above the electrode 6a of the resistance switch 6 (see FIG. 6). At this time, for example, as shown in FIG. Is in a state of being cut off from the substrate 4 and the signal line 7 (that is, a state in which no taper is provided), the main body portion 6b of the resistance switch 6 laminated thereon corresponds to the edge portion of the electrode 6a. There is a case where a break occurs at the portion (see the arrow in the figure).
特に、本実施形態では、抵抗スイッチ6の本体部6bは、厚さ数nm~数十nm程度の薄膜状に形成されるため、このような段切れが生じ易い。そして、このように段切れが生じると、その段切れを境に電流が流れ難くなり、抵抗スイッチ6が所定の機能を奏さなくなる虞れがある。
In particular, in this embodiment, the main body portion 6b of the resistance switch 6 is formed in a thin film having a thickness of about several nanometers to several tens of nanometers. When a break occurs in this way, it becomes difficult for current to flow at the break, and the resistance switch 6 may not perform a predetermined function.
そこで、このような事態が生じることを防止するために、本実施形態では、上記のように電極6aのエッジ部分を基板4や信号線7から切り立った状態とせず、図6や図8Bに示したように、電極6aのエッジ部分がテーパ状になるように形成されるようになっている。
Therefore, in order to prevent such a situation from occurring, in the present embodiment, the edge portion of the electrode 6a is not separated from the substrate 4 or the signal line 7 as described above, and is shown in FIGS. 6 and 8B. As described above, the edge portion of the electrode 6a is formed to be tapered.
このように電極6aのエッジ部分をテーパ状に形成する方法としては、例えば、以下のよう方法を採用することが可能である。
For example, the following method can be adopted as a method of forming the edge portion of the electrode 6a in a tapered shape.
すなわち、例えば図11に示すように、基板4や信号線7の上方に、電極6aを図9Aや図9Bに示したように積層する。そして、例えば、電極6aを取り囲むように形状を持つ基台部M1と、形成する電極6aの平面形状の開口部を持つマスク材M2で構成されたシャドーマスクを用いて電極6aを積層する。
That is, for example, as shown in FIG. 11, the electrode 6a is stacked above the substrate 4 and the signal line 7 as shown in FIGS. 9A and 9B. Then, for example, the electrode 6a is laminated by using a shadow mask constituted by a base M1 having a shape so as to surround the electrode 6a and a mask material M2 having a planar opening of the electrode 6a to be formed.
そして、このようにして、マスク材M2を電極6aに密着させないようにして位置合わせをし、いわばある程度浮き上がらせた状態で、例えばスパッタリング成膜を行う。このように処理すると、スパッタ分子が、電極6aとマスク材M2との隙間に回り込むようになり(図11の矢印参照)、電極6aのエッジ部分を的確にテーパ状に形成することが可能となる。
Then, in this way, alignment is performed so that the mask material M2 is not brought into close contact with the electrode 6a, so that, for example, sputtering film formation is performed in a state where the mask material M2 is lifted to some extent. When the treatment is performed in this manner, the sputtered molecules come into the gap between the electrode 6a and the mask material M2 (see the arrow in FIG. 11), and the edge portion of the electrode 6a can be accurately formed into a tapered shape. .
製造プロセスでは、続いて、図5や図6に示すように、電極6aの上方に、抵抗スイッチ6の本体部6bが形成される(図7のステップS2)。
In the manufacturing process, subsequently, as shown in FIGS. 5 and 6, the main body 6b of the resistance switch 6 is formed above the electrode 6a (step S2 in FIG. 7).
本実施形態では、抵抗スイッチ6の本体部6bは、電極6aを被覆するように(すなわち電極6aを覆い隠すように)形成されるようになっている。これは、上記と同様に、電極6aに対する抵抗スイッチ6の本体部6bの電極6aに対する相対的な位置が多少ずれても、抵抗スイッチ6の本体部6bが確実に電極6aと電極6cとの間に配設されるようにして、電極6aと電極6cとが直接接触しない(すなわち電気的に接続しない)ようにするためである。
In the present embodiment, the main body portion 6b of the resistance switch 6 is formed so as to cover the electrode 6a (that is, cover the electrode 6a). Similarly to the above, even if the relative position of the main body portion 6b of the resistance switch 6 with respect to the electrode 6a is slightly shifted with respect to the electrode 6a, the main body portion 6b of the resistance switch 6 is reliably connected between the electrode 6a and the electrode 6c. This is because the electrode 6a and the electrode 6c are not in direct contact (that is, are not electrically connected).
しかし、電極6aの上方に抵抗スイッチ6を形成しても電極6aと電極6cとが直接接触しないように構成できるのであれば、必ずしも抵抗スイッチ6の本体部6bで電極6aを覆い隠すように形成する必要はない。
However, if the electrode 6a and the electrode 6c can be configured not to be in direct contact with each other even if the resistor switch 6 is formed above the electrode 6a, the electrode 6a is not necessarily covered with the main body 6b of the resistor switch 6. do not have to.
本実施形態では、抵抗スイッチ6は、電圧が印加されることにより抵抗スイッチ6内に形成される電界によって抵抗値が変化するチタン酸化物(TiOx)で構成された本体部6bを電極6aと電極6c(本実施形態の場合は第1電極5a)とで挟む構成とされている。
In the present embodiment, the resistance switch 6 includes a main body 6b made of titanium oxide (TiOx) whose resistance value is changed by an electric field formed in the resistance switch 6 when a voltage is applied. 6c (in the case of the present embodiment, the first electrode 5a) is sandwiched.
抵抗スイッチ6の本体部6bは、チタン酸化物以外にも、公知の種々の材料を用いた抵抗スイッチを用いることが可能であり、好ましくは、例えばCu、Ni、Fe、Al、Hf、Zr、Ba、Sr、Ta、La、Si、Y等の遷移金属の酸化物等や、酸素欠陥を有するものが用いられる。また、それらの金属酸化物と、含有する酸素(O)等の比率が異なる金属酸化物とを混合したり、或いはそれらを2層に分けて形成することも可能である。
The main body 6b of the resistance switch 6 can be a resistance switch using various known materials other than titanium oxide, and preferably, for example, Cu, Ni, Fe, Al, Hf, Zr, An oxide of a transition metal such as Ba, Sr, Ta, La, Si, or Y, or one having an oxygen defect is used. It is also possible to mix these metal oxides and metal oxides having different ratios such as oxygen (O) contained therein or to divide them into two layers.
続いて、図5や図6に示すように、抵抗スイッチ6の本体部6bの上方の所定の位置に、本実施形態では電極6cと共通の電極とされる変換部5の第1電極5aが積層されて形成される(図7のステップS3)。本実施形態では、第1電極5aは、前述したように、抵抗スイッチ6の電極6aとは反対側の電極6cとして機能するとともに、変換部5の一方の電極としても機能する。
Subsequently, as shown in FIGS. 5 and 6, the first electrode 5 a of the conversion unit 5, which is a common electrode with the electrode 6 c in the present embodiment, is disposed at a predetermined position above the main body 6 b of the resistance switch 6. A layered structure is formed (step S3 in FIG. 7). In the present embodiment, as described above, the first electrode 5 a functions as the electrode 6 c on the opposite side of the electrode 6 a of the resistance switch 6 and also functions as one electrode of the conversion unit 5.
続いて、図5や図6に示すように、第1電極5aの上方に、変換部5の本体部5cが積層されて形成される(図7のステップS4)。
Subsequently, as shown in FIG. 5 and FIG. 6, the main body 5c of the converter 5 is laminated and formed above the first electrode 5a (step S4 in FIG. 7).
本実施形態では、変換部5の本体部5cは、下側(すなわち抵抗スイッチ6側)から順に、水素化アモルファスシリコン(a-Si)にVI族元素をドープしてn型に形成されたn層5dと、水素化アモルファスシリコンからなるi層5e(いわゆる変換層)と、水素化アモルファスシリコンにIII族元素をドープしてp型に形成されたp層5fとが積層されて形成されている。
In the present embodiment, the main body 5c of the conversion unit 5 is formed in an n-type by doping a group VI element into hydrogenated amorphous silicon (a-Si) sequentially from the lower side (that is, the resistance switch 6 side). A layer 5d, an i layer 5e (so-called conversion layer) made of hydrogenated amorphous silicon, and a p layer 5f formed into a p-type by doping a hydrogenated amorphous silicon with a group III element are formed. .
そして、イメージセンサー1に照射された光(本実施形態では、放射線画像撮影装置1に照射された放射線がシンチレーター3(図2参照)で変換された光)が入射してi層5eに到達すると、i層5e内で電子正孔対が発生するようになっている。
Then, when the light irradiated to the image sensor 1 (in this embodiment, the light irradiated to the radiation image capturing apparatus 1 is converted by the scintillator 3 (see FIG. 2)) enters the i layer 5e. Electron hole pairs are generated in the i layer 5e.
そして、前述したように、バイアス線8(図4参照)から変換部5の第2電極5bに逆バイアス電圧が印加されると、i層5e内で発生した電子が第1電極5a側に、正孔が第2電極b側にそれぞれ移動する。そのため、光の照射により変換部5c内で発生した電子や正孔が、再結合することなく、それぞれ対応する第1電極5aや第2電極5b側に移動して(すなわち図6ではi層5e内でそれぞれ上下方向に移動して)分離される。
As described above, when a reverse bias voltage is applied from the bias line 8 (see FIG. 4) to the second electrode 5b of the conversion unit 5, electrons generated in the i layer 5e are moved to the first electrode 5a side. The holes move to the second electrode b side. Therefore, electrons and holes generated in the converter 5c due to light irradiation move to the corresponding first electrode 5a and second electrode 5b side without recombination (that is, in FIG. 6, the i layer 5e). Within each other).
そして、変換部5の本体部5cが形成されると、さらにその上方に例えばITO(Indium Tin Oxide)等の透明電極として形成される第2電極5bが積層される(図7のステップS5)。
And when the main-body part 5c of the conversion part 5 is formed, the 2nd electrode 5b formed as transparent electrodes, such as ITO (Indium * Tin * Oxide), for example is further laminated | stacked on it (step S5 of FIG. 7).
本実施形態では、図12に示すように、このようにして積層した変換部5の本体部5cや第2電極5bの上方から、スパッタリング等の方法により例えば窒化シリコン(SiN)等からなる絶縁層9を形成して、抵抗スイッチ6や本体部5c等を被覆する(図7のステップS6)。
In the present embodiment, as shown in FIG. 12, an insulating layer made of, for example, silicon nitride (SiN) or the like by sputtering or the like from above the main body 5c and the second electrode 5b of the converter 5 stacked in this way. 9 is formed to cover the resistance switch 6 and the main body 5c (step S6 in FIG. 7).
そして、この状態で、第2電極5bの上方の位置の絶縁層9に、図6に示したようなコンタクトホールHを形成するようになっている(図7のステップS7)。
In this state, a contact hole H as shown in FIG. 6 is formed in the insulating layer 9 above the second electrode 5b (step S7 in FIG. 7).
その際、例えば異方性のプラズマエッチングの方法を用いて、絶縁層9にコンタクトホールHを形成すると、コンタクトホールHのエッジ部分が第2電極5bから切り立ったように形成される可能性がある。
At this time, if the contact hole H is formed in the insulating layer 9 by using, for example, an anisotropic plasma etching method, the edge portion of the contact hole H may be formed so as to stand up from the second electrode 5b. .
しかし、このようにコンタクトホールHのエッジ部分が切り立ったように形成されると、後述するようにコンタクトホールHに入り込んで第2電極5bと接続されるように形成されるバイアス線8(図6参照)が、やはりコンタクトホールHのエッジ部分で切れてしまう虞れがある。そして、段切れが生じると、バイアス線8から変換部5の第2電極5bに対して必要な電圧を印加することができなくなる。
However, when the edge portion of the contact hole H is formed so as to stand up like this, the bias line 8 formed so as to enter the contact hole H and be connected to the second electrode 5b as will be described later (FIG. 6). However, there is a possibility that the edge of the contact hole H will be cut off. When the step breaks, a necessary voltage cannot be applied from the bias line 8 to the second electrode 5b of the conversion unit 5.
そこで、本実施形態では、コンタクトホールHを形成する方法として、ケミカルドライエッチングの方法が採用されるようになっている。この方法では、絶縁層9のコンタクトホールHを形成したい部分の直上ではなく、別の反応室でガスを分解し、生成されたラジカルを当該部分に輸送してエッチング処理を行う。
Therefore, in this embodiment, a chemical dry etching method is adopted as a method for forming the contact hole H. In this method, the gas is decomposed in another reaction chamber, not directly above the portion of the insulating layer 9 where the contact hole H is to be formed, and the generated radicals are transported to the portion to perform the etching process.
このようなエッチング処理を行うと、絶縁層9等にダメージを与えないという特徴のほかに、ほぼ等方性エッチングに近いエッチング処理が可能となるため、図6に示したように、形成されたコンタクトホールHのエッジ部分をテーパ状にすることが可能となる。そして、コンタクトホールHのエッジ部分がテーパ状になっているため、バイアス線8がコンタクトホールHのエッジ部分で切断されることを的確に防止することが可能となる。
When such an etching process is performed, in addition to the feature that the insulating layer 9 and the like are not damaged, an etching process almost similar to an isotropic etching can be performed. Therefore, as shown in FIG. The edge portion of the contact hole H can be tapered. Since the edge portion of the contact hole H is tapered, it is possible to accurately prevent the bias line 8 from being cut at the edge portion of the contact hole H.
なお、上記の目的を達成することができる手法であれば、ケミカルドライエッチング以外の手法でも望ましく、また、例えばプラズマエッチングの方法を用いてもバイアス線8の切断等が生じないのであれば、プラズマエッチングの方法を採用することも可能である。
Any technique other than chemical dry etching may be used as long as it can achieve the above-mentioned purpose. For example, if the cutting of the bias line 8 does not occur even if the plasma etching method is used, plasma is used. It is also possible to employ an etching method.
このようにして、絶縁層9にテーパ状のコンタクトホールHが形成されると、続いて、絶縁層9上にバイアス線8が配線され、バイアス線8が、コンタクトホールHを介して変換部5の第2電極5bに接続されるようになっている(図7のステップS8)。本実施形態では、バイアス線8は、アルミニウム等の金属線で構成されている。
When the tapered contact hole H is formed in the insulating layer 9 in this way, subsequently, the bias line 8 is wired on the insulating layer 9, and the bias line 8 is connected to the conversion unit 5 via the contact hole H. The second electrode 5b is connected (step S8 in FIG. 7). In the present embodiment, the bias line 8 is made of a metal wire such as aluminum.
なお、図6等では、凹凸を有する絶縁層9上にバイアス線8を直接配線する場合を示したが、バイアス線8が不要に切断されることを防止するために、例えば、絶縁層9の凹凸をなくすように、絶縁層9の凹部に樹脂を充填する等して絶縁層9の表面を平坦化したうえで、バイアス線8を配線するように構成することも可能である。
In FIG. 6 and the like, the case where the bias line 8 is directly wired on the insulating layer 9 having projections and depressions is shown, but in order to prevent the bias line 8 from being unnecessarily cut, for example, the insulating layer 9 In order to eliminate the unevenness, the bias line 8 may be wired after the surface of the insulating layer 9 is flattened by filling the concave portion of the insulating layer 9 with a resin or the like.
また、図5や図6等では、コンタクトホールHを、抵抗スイッチ6の電極6aや本体部6b等の真上に形成する場合を示したが、コンタクトホールHの形成位置やバイアス線8の配線位置はこれに限定されない。コンタクトホールHやバイアス線8を上記以外の位置に形成、配線するように構成することも可能であり、例えば、変換部5の第2電極5bの端部等にコンタクトホールHを設けるように構成することも可能である。また、バイアス線8を、各変換部5の間の部分に配線するように構成することも可能である。
5 and 6 show the case where the contact hole H is formed immediately above the electrode 6a of the resistance switch 6 and the main body 6b. However, the formation position of the contact hole H and the wiring of the bias line 8 are shown. The position is not limited to this. The contact hole H and the bias line 8 may be formed and wired at positions other than the above. For example, the contact hole H may be provided at the end of the second electrode 5b of the conversion unit 5 or the like. It is also possible to do. It is also possible to configure the bias line 8 to be wired in a portion between the conversion units 5.
次に、以上のような構成の本実施形態に係るイメージセンサー1を用いて撮影を行う場合の画像データの読み出し処理における具体的な制御の仕方等について説明する。また、それとあわせて本実施形態に係るイメージセンサー1や放射線画像撮影装置100の作用についても説明する。
Next, a specific control method and the like in the image data reading process when shooting is performed using the image sensor 1 according to the present embodiment having the above-described configuration will be described. In addition, the operation of the image sensor 1 and the radiographic image capturing apparatus 100 according to the present embodiment will also be described.
なお、以下では、本実施形態に係る上記のイメージセンサー1を用いた放射線画像撮影装置100を用いて放射線画像撮影を行う場合について説明するが、例えばイメージセンサー1がデジタルカメラ等の他の撮影機器のイメージセンサーとして用いる場合には、それに適した制御の仕方で用いられることは言うまでもない。
In the following, a case where radiographic imaging is performed using the radiographic imaging apparatus 100 using the image sensor 1 according to the present embodiment will be described. For example, the imaging sensor 1 is another imaging device such as a digital camera. Needless to say, the image sensor is used in a control method suitable for it.
本実施形態では、放射線画像撮影装置100内のイメージセンサー1の制御手段20(図4参照)は、放射線画像撮影において放射線画像撮影装置100に対して放射線が照射される前に、切替ドライバー10から各バイアス線8を介して各変換部5の第2電極5bにそれぞれ印加する電圧の電圧値を制御して、各抵抗スイッチ6をそれぞれ高抵抗の状態に切り替えるようになっている。
In the present embodiment, the control means 20 (see FIG. 4) of the image sensor 1 in the radiographic image capturing apparatus 100 receives the radiation from the switching driver 10 before the radiation image capturing apparatus 100 is irradiated with radiation. Each resistance switch 6 is switched to a high resistance state by controlling the voltage value of the voltage applied to each second electrode 5b of each converter 5 via each bias line 8.
各変換部5の抵抗スイッチ6が高抵抗の状態に切り替えられることで、照射された放射線がシンチレーター3で光に変換され、変換された光が照射されることにより各変換部5のi層5e内で電荷が発生した際に、電荷が各変換部5内に適切に蓄積される状態になる。制御手段20は、このようにして、各変換部5を、放射線の照射により各変換部5のi層5e内で発生した電荷を各i層5e内に蓄積させる電荷蓄積状態に移行させるようになっている。
By switching the resistance switch 6 of each conversion unit 5 to a high resistance state, the irradiated radiation is converted into light by the scintillator 3, and the converted light is irradiated, whereby the i layer 5e of each conversion unit 5 is irradiated. When charge is generated in the converter, the charge is appropriately accumulated in each conversion unit 5. In this way, the control unit 20 causes each conversion unit 5 to shift to a charge accumulation state in which charges generated in the i layer 5e of each conversion unit 5 due to radiation irradiation are accumulated in each i layer 5e. It has become.
そして、上記のように各変換部5を電荷蓄積状態に移行させた後、放射線の照射が終了すると、制御手段20は、切替ドライバー10や読み出し回路14等(図4参照)の動作を制御して、各変換部5から、放射線の照射により各i層5e内で発生した電荷を画像データとして読み出す画像データの読み出し処理を行わせるようになっている。
When the irradiation of the radiation is completed after the conversion units 5 are shifted to the charge accumulation state as described above, the control unit 20 controls the operation of the switching driver 10, the readout circuit 14, and the like (see FIG. 4). Thus, each conversion unit 5 performs image data read processing for reading out the charges generated in each i-layer 5e as a result of radiation irradiation as image data.
この画像データの読み出し処理の際、本実施形態では、制御手段20は、切替ドライバー10から各バイアス線8を介して各変換部5に印加する電圧の電圧値を制御して各抵抗スイッチ6を低抵抗の状態に切り替えて、各読み出し回路14にそれぞれ画像データを読み出させるようになっている。
In this image data reading process, in the present embodiment, the control unit 20 controls the voltage value of the voltage applied from the switching driver 10 to each conversion unit 5 via each bias line 8 to control each resistance switch 6. Switching to the low resistance state allows each readout circuit 14 to read out image data.
そして、制御手段20は、この処理を、切替ドライバー10から印加する電圧の電圧値を切り替えるバイアス線8をシフトさせながら順次行わせ、各バイアス線8に接続されている各変換部5から電荷を信号線7に順次放出させ、それを各読み出し回路14で画像データとして順次読み出していくように制御することにより、各変換部5からそれぞれ画像データを読み出させるようになっている。
Then, the control means 20 sequentially performs this process while shifting the bias line 8 that switches the voltage value of the voltage applied from the switching driver 10, and charges are transferred from the conversion units 5 connected to the bias lines 8. By sequentially discharging the signal lines 7 and sequentially reading them as image data by the respective readout circuits 14, the image data is read out from the respective converters 5.
以下、制御手段20による上記の処理の具体的な制御の仕方について説明する。
Hereinafter, a specific control method of the above processing by the control means 20 will be described.
なお、抵抗スイッチ6には、後述するように、主にユニポーラ(ノンポーラ型ともいう。)の抵抗スイッチと、バイポーラ型の抵抗スイッチがあるが、まず、抵抗スイッチ6としてバイポーラ型の抵抗スイッチを用いた場合の、制御手段20による画像データの読み出し処理等について説明する。
As will be described later, the resistance switch 6 mainly includes a unipolar (also referred to as non-polar) resistance switch and a bipolar resistance switch. First, a bipolar resistance switch is used as the resistance switch 6. A description will be given of the image data read processing by the control means 20 in the case of such a case.
図13は、印加する電圧Vが正の電圧のある閾値を越えると、低抵抗の状態から高抵抗の状態に切り替わり、負の電圧のある閾値を越えると、高抵抗の状態から低抵抗の状態に切り替わるタイプのバイポーラ型抵抗スイッチの一例を説明するグラフである。
FIG. 13 shows that when the applied voltage V exceeds a certain threshold value of the positive voltage, the low resistance state is switched to the high resistance state, and when the applied voltage V exceeds a certain threshold value of the negative voltage, the high resistance state is changed to the low resistance state. It is a graph explaining an example of the bipolar resistance switch of the type switched to.
このタイプのバイポーラ型の抵抗スイッチ6では、図13に示すように、抵抗スイッチ6に印加される電圧Vの向き(極性ともいう。)を正負で逆転させることで初めて抵抗スイッチ6の抵抗値を高抵抗の状態と低抵抗の状態との間で遷移させることができる。
In this type of bipolar resistance switch 6, as shown in FIG. 13, the resistance value of the resistance switch 6 is not changed until the direction of the voltage V (also referred to as polarity) applied to the resistance switch 6 is reversed between positive and negative. A transition can be made between a high resistance state and a low resistance state.
すなわち、例えば高抵抗の状態である抵抗スイッチ6に、抵抗スイッチ6に印加する電圧Vすなわち抵抗スイッチ6における電極6a-第1電極5a間の電位Vの絶対値が所定の電圧値Vrsを越えると、抵抗スイッチ6の抵抗値が低抵抗の状態に遷移する。また、抵抗スイッチ6の抵抗値が低抵抗の状態である場合に、抵抗スイッチ6に印加される電圧Vの極性を変え、その絶対値が所定の電圧値Vstを越えると、抵抗スイッチ6の抵抗値が高抵抗の状態に遷移するようになっている。
That is, for example, when the voltage V applied to the resistance switch 6, that is, the absolute value of the potential V between the electrode 6 a and the first electrode 5 a in the resistance switch 6 exceeds a predetermined voltage value Vrs when the resistance switch 6 is in a high resistance state. The resistance value of the resistance switch 6 transitions to a low resistance state. Further, when the resistance value of the resistance switch 6 is in a low resistance state, if the polarity of the voltage V applied to the resistance switch 6 is changed and its absolute value exceeds a predetermined voltage value Vst, the resistance of the resistance switch 6 The value transitions to a high resistance state.
印加する電圧Vに応じて抵抗値が変化するタイプのバイポーラ型の抵抗スイッチ6では、このようにして、印加する電圧Vの向きを変えながら、印加する電圧Vの電圧値を変えることで、抵抗スイッチ6の抵抗値を可変させることができるようになっている。
In the bipolar resistance switch 6 of which the resistance value changes according to the voltage V to be applied, the resistance value is changed by changing the voltage value of the voltage V to be applied while changing the direction of the voltage V to be applied. The resistance value of the switch 6 can be varied.
抵抗スイッチ6として上記のようなバイポーラ型の抵抗スイッチが用いられている場合には、制御手段20は、以下のように制御して、画像データの読み出し処理等を行うように構成される。この場合、電荷蓄積状態では抵抗スイッチ6の抵抗値を高抵抗の状態とし、画像データの読み出し処理の際には抵抗スイッチ6の抵抗値を低抵抗の状態に切り替えるようにして処理が行われる。以下、図14を用いて具体的に説明する。
When the above-described bipolar resistance switch is used as the resistance switch 6, the control means 20 is configured to perform image data read processing and the like by controlling as follows. In this case, in the charge accumulation state, the resistance value of the resistance switch 6 is set to a high resistance state, and in the image data reading process, the resistance value of the resistance switch 6 is switched to a low resistance state. Hereinafter, this will be specifically described with reference to FIG.
図14は、バイポーラ型の抵抗スイッチ6を用いた場合に変換部5の第2電極5bに印加される電圧Vbや抵抗スイッチ6の電極6aと第1電極5aの間にかかる電圧V等の時間的推移を表すグラフである。
FIG. 14 shows a time such as the voltage Vb applied to the second electrode 5b of the conversion unit 5 and the voltage V applied between the electrode 6a of the resistance switch 6 and the first electrode 5a when the bipolar resistance switch 6 is used. It is a graph showing a target transition.
図14の左端の時点では、各変換部5は、既に抵抗スイッチ6の抵抗値が高抵抗の状態になっているものとする。そして、この状態では、制御手段20は、各変換部5の第2電極5bに印加する電圧をVbとして、バイアス電源11(図4参照)から供給される所定の電圧値Vbiasの逆バイアス電圧が切替ドライバー10から各バイアス線8を介して各変換部5の第2電極5bに印加されて、各変換部5が電荷蓄積状態とされているものとする。
14, it is assumed that the resistance value of the resistance switch 6 is already in a high resistance state in each conversion unit 5 at the time of the left end in FIG. In this state, the control means 20 uses the voltage applied to the second electrode 5b of each converter 5 as Vb, and the reverse bias voltage of the predetermined voltage value Vbias supplied from the bias power supply 11 (see FIG. 4) is It is assumed that each conversion unit 5 is in a charge accumulation state by being applied from the switching driver 10 to the second electrode 5b of each conversion unit 5 via each bias line 8.
この状態では、抵抗スイッチ6の抵抗値が高抵抗の状態にあるため、各変換部5のi層5e(図6等参照)内で発生した電荷が信号線7にほとんど流出しない状態になっている。以下、この状態から説明を開始する。
In this state, since the resistance value of the resistance switch 6 is in a high resistance state, the charge generated in the i layer 5e (see FIG. 6 and the like) of each converter 5 hardly flows out to the signal line 7. Yes. Hereinafter, the description starts from this state.
一方、各変換部5では、通常、各変換部5自体の熱(温度)による熱励起等によりいわゆる暗電流(暗電荷ともいう。)が常時発生しており、この暗電流が、高抵抗の抵抗スイッチ6に阻止されて信号線7に流出されずに、各変換部5の本体部5c内に蓄積される。そのため、図14の左端部分に示すように、第1電極5aの電圧Vが、発生する暗電流の量に応じて僅かずつ下がっていく状態になっている。
On the other hand, in each conversion unit 5, a so-called dark current (also referred to as dark charge) is normally generated due to thermal excitation by heat (temperature) of each conversion unit 5 itself, and this dark current is a high resistance. Instead of being blocked by the resistance switch 6 and flowing out to the signal line 7, it is accumulated in the main body 5 c of each converter 5. Therefore, as shown in the left end portion of FIG. 14, the voltage V of the first electrode 5a is in a state of gradually decreasing according to the amount of dark current generated.
図14に示すように、続いて、放射線画像撮影装置100に対して放射線が照射されると(すなわちイメージセンサー1に光が照射されると)、変換部5のi層5e内で上記のように電子正孔対が発生し、発生した電子や正孔がそれぞれ第1電極5aや第2電極5b側に移動して分離される。そのため、この時点で、抵抗スイッチ6の電極6aと第1電極5aの電位差Vが発生した電荷量に応じて大きく拡大し、第1電極5aの電圧Vが大きく低下する。
As shown in FIG. 14, when radiation is subsequently applied to the radiation image capturing apparatus 100 (that is, when light is applied to the image sensor 1), the above-mentioned is performed in the i layer 5 e of the conversion unit 5. An electron-hole pair is generated in the first electrode, and the generated electrons and holes move to the first electrode 5a and the second electrode 5b, respectively, and are separated. Therefore, at this time, the potential difference V between the electrode 6a of the resistance switch 6 and the first electrode 5a greatly increases according to the amount of charge generated, and the voltage V of the first electrode 5a greatly decreases.
そして、制御手段20は、放射線画像撮影装置100に対する放射線の照射が終了すると(すなわちイメージセンサー1に対する光の照射が終了すると)、各変換部5からの画像データの読み出し処理を開始するようになっている。
Then, when the irradiation of radiation to the radiographic image capturing apparatus 100 is completed (that is, when the irradiation of light to the image sensor 1 is completed), the control unit 20 starts reading processing of image data from each conversion unit 5. ing.
画像データの読み出し処理では、図14に示すように、制御手段20は、切替ドライバー10から最初のバイアス線8aに印加する電圧Vbを、それまでの逆バイアス電圧Vbiasから一気に下げる。すなわち、切替ドライバー10から当該バイアス線8aに印加する電圧Vbを、バイアス電源11(図4参照)から供給されている所定の電圧値の逆バイアス電圧Vbiasから、第1電源回路12aから供給されている、逆バイアス電圧Vbiasよりも低い電圧値の電圧Vbに切り替えさせる。なお、その際、他のバイアス線8b、8c、…に印加する電圧Vbは逆バイアス電圧Vbiasのままである。
In the image data reading process, as shown in FIG. 14, the control means 20 reduces the voltage Vb applied to the first bias line 8a from the switching driver 10 from the reverse bias voltage Vbias so far. That is, the voltage Vb applied from the switching driver 10 to the bias line 8a is supplied from the first power supply circuit 12a from the reverse bias voltage Vbias having a predetermined voltage value supplied from the bias power supply 11 (see FIG. 4). The voltage Vb is lower than the reverse bias voltage Vbias. At this time, the voltage Vb applied to the other bias lines 8b, 8c,... Remains the reverse bias voltage Vbias.
すると、抵抗スイッチ6の電極6aと第1電極5aの電位差Vの絶対値が所定の電圧値Vstを越えるため、バイポーラ型の抵抗スイッチ6の抵抗値が高抵抗の状態から低抵抗の状態に遷移する。そのため、低抵抗の状態になった抵抗スイッチ6を介して変換部5のi層5e内で発生した電荷が信号線7に放出される。
Then, since the absolute value of the potential difference V between the electrode 6a of the resistance switch 6 and the first electrode 5a exceeds a predetermined voltage value Vst, the resistance value of the bipolar resistance switch 6 transitions from a high resistance state to a low resistance state. To do. Therefore, the charge generated in the i layer 5e of the conversion unit 5 is released to the signal line 7 through the resistance switch 6 in a low resistance state.
そして、変換部5の本体部5c内に蓄積され第1電極5aと第2電極5bに分離されていた電子や正孔の量が減るため、第1電極5aと第2電極5bの間の電位差、すなわち上記の電圧Vと電圧Vbとの差V-Vbが、放射線の照射前の元の電位差に戻るようにして大きくなっていく。そして、それに伴って抵抗スイッチ6の電極6aと第1電極5aの電位差Vが縮小していき、第1電極5aの電圧Vが上昇していく。
And since the quantity of the electron and the hole which were accumulate | stored in the main-body part 5c of the conversion part 5, and were isolate | separated into the 1st electrode 5a and the 2nd electrode 5b reduces, the electric potential difference between the 1st electrode 5a and the 2nd electrode 5b That is, the difference V−Vb between the voltage V and the voltage Vb increases so as to return to the original potential difference before irradiation with radiation. Accordingly, the potential difference V between the electrode 6a of the resistance switch 6 and the first electrode 5a is reduced, and the voltage V of the first electrode 5a is increased.
また、低抵抗の状態になった抵抗スイッチ6を介して変換部5のi層5e内で発生した電荷が信号線7に放出されると、各電荷がそれぞれ対応する読み出し回路14に流入し、上記のようにして読み出し回路14等によりそれぞれ画像データとして読み出され、それぞれ記憶手段21に出力されて順次保存される。
Further, when the charge generated in the i layer 5e of the conversion unit 5 is released to the signal line 7 through the resistance switch 6 in a low resistance state, each charge flows into the corresponding readout circuit 14, As described above, the data is read out as image data by the readout circuit 14 and the like, respectively output to the storage means 21 and sequentially stored.
制御手段20は、各変換部5からの電荷の放出が終わった段階で、抵抗スイッチ6の抵抗値を高抵抗の状態に遷移させるために、図14に示すように、切替ドライバー10から最初のバイアス線8aに印加する電圧Vbを一気に上げて、電圧Vbが所定の正の電圧値になるようにする。
As shown in FIG. 14, the control means 20 starts the first switching driver 10 from the switching driver 10 in order to shift the resistance value of the resistance switch 6 to the high resistance state at the stage where the discharge of the electric charges from each conversion unit 5 is finished. The voltage Vb applied to the bias line 8a is increased at a stroke so that the voltage Vb becomes a predetermined positive voltage value.
すなわち、制御手段20は、切替ドライバー10から当該バイアス線8aに印加されている電圧Vbを、第1電源回路12a(図4参照)から供給されている、逆バイアス電圧Vbiasよりも低い電圧値の電圧Vbから、第2電源回路12bから供給されている、所定の正の電圧値の電圧Vbに切り替えさせる。
That is, the control means 20 has a voltage value lower than the reverse bias voltage Vbias supplied from the first power supply circuit 12a (see FIG. 4) by applying the voltage Vb applied from the switching driver 10 to the bias line 8a. The voltage Vb is switched to the voltage Vb having a predetermined positive voltage value supplied from the second power supply circuit 12b.
すると、抵抗スイッチ6の電極6aと第1電極5aの電位差Vすなわち第1電極5aの電圧Vが一気に押し上げられて正の電圧値に遷移して所定の電圧値Vrsを越える。そのため、バイポーラ型の抵抗スイッチ6の抵抗値が、今度は、低抵抗の状態から高抵抗の状態に遷移する。
Then, the potential difference V between the electrode 6a of the resistance switch 6 and the first electrode 5a, that is, the voltage V of the first electrode 5a is pushed up at a stretch to change to a positive voltage value and exceed a predetermined voltage value Vrs. For this reason, the resistance value of the bipolar resistance switch 6 transitions from a low resistance state to a high resistance state this time.
しかし、この状態では、変換部5の本体部5cにいわゆる順方向のバイアスがかかった状態になるため、抵抗スイッチ6を含む変換部5中を大きな電流が流れる状態になってしまう。
However, in this state, since a so-called forward bias is applied to the main body 5c of the conversion unit 5, a large current flows through the conversion unit 5 including the resistance switch 6.
そのため、制御手段20は、図14に示すように、当該バイアス線8aに接続されている各変換部5の抵抗スイッチ6が高抵抗の状態になると、即座に切替ドライバー10からバイアス線8aに印加する電圧Vbを元の逆バイアス電圧Vbiasに戻す。すなわち、制御手段20は、切替ドライバー10から当該バイアス線8aに印加されている電圧Vbを、第2電源回路12bから供給されている所定の正の電圧値の電圧Vbから、バイアス電源11から供給されている所定の電圧値の逆バイアス電圧Vbiasに切り替えさせる。
For this reason, as shown in FIG. 14, when the resistance switch 6 of each converter 5 connected to the bias line 8a is in a high resistance state, the control means 20 immediately applies the switching driver 10 to the bias line 8a. The voltage Vb to be returned is returned to the original reverse bias voltage Vbias. That is, the control unit 20 supplies the voltage Vb applied to the bias line 8a from the switching driver 10 from the bias power supply 11 from the voltage Vb having a predetermined positive voltage value supplied from the second power supply circuit 12b. The reverse bias voltage Vbias having a predetermined voltage value is switched.
本実施形態では、このようにして、当該バイアス線8aに接続されている各変換部5を元の電荷蓄積状態に戻すように構成される。
In this embodiment, the conversion units 5 connected to the bias line 8a are thus returned to the original charge accumulation state.
このように、抵抗スイッチ6を高抵抗の状態に切り替えるとすぐに変換部5に逆バイアス電圧Vbiasを印加する状態に戻すように構成すれば、各変換部5に順バイアスがかかっている期間が非常に短縮される。
In this way, if the resistance switch 6 is switched back to the high resistance state and immediately returned to the state in which the reverse bias voltage Vbias is applied to the conversion unit 5, the period during which each conversion unit 5 is forward-biased can be obtained. Very shortened.
そして、各変換部5に順バイアスがかかっても実際に各変換部5内を大きな電流が流れ出すまでには時定数的な遅れがあるため、上記のように各変換部5に印加する電圧Vbを即座に逆バイアス電圧Vbiasに切り替えるように構成すれば、上記のように電圧Vbを可変させても、事実上、各変換部5中を大きな電流が流れることを防止することが可能となる。
Even if a forward bias is applied to each converter 5, there is a time constant delay until a large current actually flows through each converter 5, so that the voltage Vb applied to each converter 5 as described above. Is immediately switched to the reverse bias voltage Vbias, even if the voltage Vb is varied as described above, it is practically possible to prevent a large current from flowing in each converter 5.
制御手段20は、バイアス線8aに対する上記の処理が終了すると、今度はバイアス線8bに対して同様にして読み出し処理を行い、バイアス線8bに接続されている各変換部5から画像データを読み出す。このようにして、制御手段20は、印加する電圧Vbを切り替えるバイアス線8をシフトさせながら同様に画像データの読み出し処理を順次行わせて、各バイアス線8に接続されている各変換部5(すなわち全ての変換部5)から画像データを読み出すように構成される。
When the above processing for the bias line 8a is completed, the control unit 20 performs reading processing on the bias line 8b in the same manner, and reads image data from each conversion unit 5 connected to the bias line 8b. In this manner, the control unit 20 sequentially performs the image data read processing while shifting the bias line 8 for switching the voltage Vb to be applied, so that each conversion unit 5 connected to each bias line 8 ( That is, the image data is read out from all the conversion units 5).
一方、抵抗スイッチ6としてユニポーラ型の抵抗スイッチを用いた場合も同様にして、画像データの読み出し処理等を行うことができる。図15は、印加する電圧Vの絶対値が閾値を越えると、高抵抗の状態と低抵抗の状態とが切り替わるタイプのユニポーラ型の抵抗スイッチ6における電極6a-第1電極5a(すなわち電極6c)間の電位Vと流れる電流Iとの関係を説明するグラフである。
On the other hand, when a unipolar resistance switch is used as the resistance switch 6, image data reading processing or the like can be performed in the same manner. FIG. 15 shows an electrode 6a-first electrode 5a (that is, electrode 6c) in a unipolar resistance switch 6 of a type in which a high resistance state and a low resistance state are switched when the absolute value of the applied voltage V exceeds a threshold value. It is a graph explaining the relationship between the electric potential V between and the electric current I which flows.
このタイプのユニポーラ型の抵抗スイッチ6では、図15に示すように、抵抗スイッチ6に印加される電圧Vの向き(極性ともいう。)が同一の向きである状態(すなわち印加する電圧Vが例えば負の値の電圧である状態)の中で、印加する電圧Vに応じて抵抗値が高抵抗の状態と低抵抗の状態との間を遷移する。
In this type of unipolar resistance switch 6, as shown in FIG. 15, the direction (also referred to as polarity) of the voltage V applied to the resistance switch 6 is the same (ie, the applied voltage V is, for example, In a state where the voltage is a negative value), the resistance value transitions between a high resistance state and a low resistance state according to the applied voltage V.
すなわち、このタイプのユニポーラ型の抵抗スイッチ6に例えば負の電圧Vを印加して抵抗の状態を切り替える場合、例えば、抵抗スイッチ6の抵抗値が低抵抗の状態である場合に、抵抗スイッチ6に印加される電圧Vを低下させていき、電圧Vが閾値Vrsを下回るようになると、図15に示すように、抵抗スイッチ6の抵抗値が、低抵抗の状態から高抵抗の状態に遷移する。そして、さらに電圧を低下させていき、電圧Vが閾値Vstを下回るようになると、今度は、抵抗スイッチ6の抵抗値が、高抵抗の状態から低抵抗の状態に遷移するようになっている。
That is, for example, when a negative voltage V is applied to this type of unipolar resistance switch 6 to switch the resistance state, for example, when the resistance value of the resistance switch 6 is in a low resistance state, When the applied voltage V is decreased and the voltage V falls below the threshold value Vrs, the resistance value of the resistance switch 6 transitions from a low resistance state to a high resistance state as shown in FIG. Then, when the voltage is further lowered and the voltage V becomes lower than the threshold value Vst, the resistance value of the resistance switch 6 is changed from the high resistance state to the low resistance state.
また、印加する電圧Vを上昇させていき、電圧Vがさらに上昇して正電圧側の閾値Vrsを越えた時点で、抵抗スイッチ6の抵抗値が低抵抗の状態から高抵抗の状態に遷移する。
Further, the voltage V to be applied is increased, and when the voltage V further increases and exceeds the threshold value Vrs on the positive voltage side, the resistance value of the resistance switch 6 transitions from the low resistance state to the high resistance state. .
このように印加する電圧Vに応じて抵抗値が変化するタイプのユニポーラ型の抵抗スイッチ6を用いた場合でも、例えば図16に示すように、変換部5の第2電極5bに印加する電圧Vbを可変させて、抵抗スイッチ6の電極6aと第1電極5aとの間の電圧Vを可変させることで、抵抗スイッチ6の抵抗値を可変させることができる。
Even when the unipolar resistance switch 6 whose resistance value changes in accordance with the voltage V applied in this way is used, as shown in FIG. 16, for example, the voltage Vb applied to the second electrode 5b of the conversion unit 5 , And the voltage V between the electrode 6a of the resistance switch 6 and the first electrode 5a is varied, whereby the resistance value of the resistance switch 6 can be varied.
そのため、抵抗スイッチ6としてユニポーラ型の抵抗スイッチを用いた場合でも、図14に示したバイポーラ型の抵抗スイッチ6を用いた場合と同様に、各変換部5から的確に画像データを読み出すことが可能となる。そして、図16に示すように、ユニポーラ型の場合、図14に示したバイポーラ型の場合とは異なり、変換部5に順バイアスがかかることがなくなる(すなわち電圧Vbとして正の電圧を印加する必要がなくなる)といったメリットがある。
Therefore, even when a unipolar resistance switch is used as the resistance switch 6, image data can be accurately read out from each conversion unit 5 as in the case of using the bipolar resistance switch 6 shown in FIG. It becomes. As shown in FIG. 16, in the case of the unipolar type, unlike the case of the bipolar type shown in FIG. 14, no forward bias is applied to the conversion unit 5 (that is, it is necessary to apply a positive voltage as the voltage Vb). There is a merit that
なお、前述したバイポーラ型の抵抗スイッチ6の場合も同様であるが、抵抗スイッチ6は、読み出される画像データにおけるS/N比の観点から、高抵抗の状態における抵抗値と低抵抗の状態における抵抗値との比が105以上のものが用いられることが望ましい。
The same applies to the bipolar resistance switch 6 described above, but the resistance switch 6 has a resistance value in a high resistance state and a resistance value in a low resistance state from the viewpoint of the S / N ratio in the read image data. It is desirable to use one having a ratio to the value of 10 5 or more.
また、前述したように、抵抗スイッチ6が高抵抗の状態では、各変換部5内に暗電流が蓄積され続けるため、蓄積された暗電流等を各変換部5内から各信号線7に放出されて除去する各変換部5のリセット処理が行われる場合がある。
Further, as described above, when the resistance switch 6 is in a high resistance state, dark current continues to be accumulated in each conversion unit 5, so that the accumulated dark current or the like is discharged from each conversion unit 5 to each signal line 7. In some cases, the reset process of each conversion unit 5 to be removed is performed.
この各変換部5のリセット処理においても、上記と同様にして切替ドライバー10から各バイアス線8を介して各変換部5の第2電極5bに印加する電圧Vbを、画像データの読み出し処理の場合と同様に下降させたり上昇させたりすることで、各抵抗スイッチ6の抵抗値を高抵抗の状態と低抵抗の状態との間で切り替えて、各変換部5内に残存する電荷を的確に除去することができる。
Also in the reset process of each conversion unit 5, the voltage Vb applied to the second electrode 5 b of each conversion unit 5 from the switching driver 10 via each bias line 8 is read out in the same manner as described above. The resistance value of each resistance switch 6 is switched between a high resistance state and a low resistance state by lowering or raising in the same manner as in the above, and charges remaining in each conversion unit 5 are accurately removed. can do.
以上のように、本実施形態に係るイメージセンサー1や放射線画像撮影装置100によれば、各変換部5のスイッチ素子として抵抗スイッチ6を用いるように構成したため、例えば図6等に示したように、変換部5の構造をより単純化することが可能となる。
As described above, according to the image sensor 1 and the radiographic image capturing apparatus 100 according to the present embodiment, since the resistance switch 6 is used as the switch element of each conversion unit 5, for example, as illustrated in FIG. The structure of the conversion unit 5 can be further simplified.
また、本実施形態に係るイメージセンサー1や放射線画像撮影装置100のように各変換部5のスイッチ素子として抵抗スイッチ6を用いるように構成すると、抵抗スイッチ6のオン/オフ動作、すなわち高抵抗の状態と低抵抗の状態との間の遷移を、バイアス線8を介して各変換部5の第2電極5bに印加する電圧Vbを可変させることで行うことが可能となる。そして、例えば図17に示した従来の変換部Aのようにスイッチ素子としてTFTを用いないため、イメージセンサー1や放射線画像撮影装置100に、TFTにオン/オフ動作をさせるための電圧を印加する走査線Gaを設ける必要がなくなる。
Further, when the resistor switch 6 is used as the switch element of each conversion unit 5 as in the image sensor 1 and the radiographic imaging apparatus 100 according to the present embodiment, the on / off operation of the resistor switch 6, that is, a high resistance operation. The transition between the state and the low resistance state can be performed by varying the voltage Vb applied to the second electrode 5b of each converter 5 via the bias line 8. Then, for example, since a TFT is not used as a switching element as in the conventional conversion unit A shown in FIG. 17, a voltage for turning on / off the TFT is applied to the image sensor 1 and the radiation image capturing apparatus 100. There is no need to provide the scanning line Ga.
このように、従来のイメージセンサーや放射線画像撮影装置では基板上に走査線Gaを設けるためのスペースを確保したり、他の配線との間で短絡等が生じないようにするために走査線Gaの周囲に絶縁層を設ける等の措置が必要であったが、本実施形態に係るイメージセンサー1や放射線画像撮影装置100では、走査線Gaが不要となり、上記のような措置をとる必要もなくなる。
As described above, in the conventional image sensor and radiographic apparatus, the scanning line Ga is provided in order to secure a space for providing the scanning line Ga on the substrate and to prevent a short circuit from occurring with other wirings. However, in the image sensor 1 and the radiographic imaging apparatus 100 according to the present embodiment, the scanning line Ga is not necessary, and it is not necessary to take the above-described measures. .
そのため、イメージセンサー1や放射線画像撮影装置100の基板4上での変換部5や抵抗スイッチ6、信号線7、バイアス線8等のレイアウトの自由度が拡大する等の有益な効果が得られる。
Therefore, beneficial effects such as an increase in the degree of freedom of layout of the conversion unit 5, the resistance switch 6, the signal line 7, the bias line 8, etc. on the substrate 4 of the image sensor 1 or the radiographic imaging device 100 can be obtained.
また、従来の変換部の製造プロセスでは、TFTを形成するために、成膜やレジスト塗布、露光、現像、ポストベーク、エッチング、レジスト剥離等の種々の工程からなるPEP(Photo Etching Process)を繰り返し行う必要があった。しかし、本実施形態に係る変換部5の製造プロセスにおいては、抵抗スイッチ6等の積層を、例えばシャドーマスクを用いた、より簡単な方法で行うことができる。
In addition, in the conventional conversion part manufacturing process, in order to form TFTs, PEP (Photo Etching Process) consisting of various processes such as film formation, resist coating, exposure, development, post-baking, etching, and resist stripping is repeated. There was a need to do. However, in the manufacturing process of the conversion unit 5 according to the present embodiment, the resistive switches 6 and the like can be stacked by a simpler method using, for example, a shadow mask.
そのため、本実施形態に係る変換部5を簡単な製造プロセスにより製造することが可能となり、本実施形態に係る変換部5やイメージセンサー1、放射線画像撮影装置100をより簡易な生産工程で製造することが可能となる。また、そのため、変換部5やイメージセンサー1、放射線画像撮影装置100の生産性を向上させることが可能となるとともに、生産における歩留まりの向上を図ることが可能となるといった有益な効果を得ることも可能となる。
Therefore, the conversion unit 5 according to the present embodiment can be manufactured by a simple manufacturing process, and the conversion unit 5, the image sensor 1, and the radiation image capturing apparatus 100 according to the present embodiment are manufactured by a simpler production process. It becomes possible. For this reason, it is possible to improve the productivity of the conversion unit 5, the image sensor 1, and the radiation image capturing apparatus 100, and to obtain a beneficial effect that it is possible to improve the production yield. It becomes possible.
なお、本発明が上記の実施形態に限定されず、本発明の趣旨を逸脱しない限り、適宜変更可能であることは言うまでもない。
Needless to say, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.
イメージセンサーおよびそれを用いた放射線画像撮影装置の分野において利用可能性がある。
There is a possibility of being used in the field of image sensors and radiographic imaging devices using the same.
1 イメージセンサー
4 基板
5 変換部
5a 第1電極、抵抗スイッチの電極
5b 第2電極
6 抵抗スイッチ
7 信号線
8 バイアス線
10 切替ドライバー
14 読み出し回路
20 制御手段
100 放射線画像撮影装置
V 抵抗スイッチに印加される電圧
Vb 変換部に印加する電圧 DESCRIPTION OFSYMBOLS 1 Image sensor 4 Board | substrate 5 Conversion part 5a 1st electrode, electrode 5b of resistance switch 2nd electrode 6 Resistance switch 7 Signal line 8 Bias line 10 Switching driver 14 Reading circuit 20 Control means 100 Radiation imaging device V Applied to resistance switch Voltage Vb Voltage applied to the converter
4 基板
5 変換部
5a 第1電極、抵抗スイッチの電極
5b 第2電極
6 抵抗スイッチ
7 信号線
8 バイアス線
10 切替ドライバー
14 読み出し回路
20 制御手段
100 放射線画像撮影装置
V 抵抗スイッチに印加される電圧
Vb 変換部に印加する電圧 DESCRIPTION OF
Claims (9)
- 基板上に二次元状に配列された、第1電極および第2電極を備える複数の変換部と、
前記各変換部の第1電極とそれぞれ電気的に接続されるように設けられ、電圧印加により抵抗値が変化する各抵抗スイッチと、
二次元状に配列された前記各変換部の各列ごとに、それぞれ前記各抵抗スイッチと接続されるように配線された各信号線と、
二次元状に配列された前記各変換部の各行ごとに、それぞれ前記各変換部の第2電極と接続されるように配線され、前記各変換部に電圧を印加する各バイアス線と、
前記各バイアス線ごとに印加する電圧の電圧値を切り替える切替ドライバーと、
前記変換部から対応する前記信号線に放出された電荷を画像データに変換して読み出す、前記各信号線ごとに設けられた各読み出し回路と、
少なくとも前記切替ドライバーおよび前記各読み出し回路の動作を制御して、前記各変換部から、光の照射により前記各変換部内で発生した電荷を前記画像データとして読み出す画像データの読み出し処理を行わせる制御手段と、
を備えることを特徴とするイメージセンサー。 A plurality of converters including a first electrode and a second electrode arranged two-dimensionally on a substrate;
Each resistance switch that is provided so as to be electrically connected to the first electrode of each of the conversion units, and whose resistance value changes by voltage application;
Each signal line wired so as to be connected to each of the resistance switches for each column of the conversion units arranged two-dimensionally,
For each row of each of the converters arranged in a two-dimensional manner, each bias line wired to be connected to the second electrode of each converter, and applying a voltage to each converter,
A switching driver for switching the voltage value of the voltage applied to each bias line;
Each readout circuit provided for each of the signal lines, which converts the charges discharged from the conversion unit to the corresponding signal lines into image data and reads out the image data;
Control means for controlling the operation of at least the switching driver and each readout circuit to read out the image data from the respective conversion units to read out the electric charges generated in the respective conversion units by the light irradiation as the image data. When,
An image sensor comprising: - 前記制御手段は、
前記切替ドライバーから前記各バイアス線を介して前記各変換部に印加する電圧の電圧値を制御して前記各抵抗スイッチを高抵抗の状態に切り替えて、光の照射により前記各変換部内で発生した電荷を前記各変換部内に蓄積させる電荷蓄積状態に移行させ、
前記電荷蓄積状態の後、前記画像データの読み出し処理の際には、前記切替ドライバーから前記各バイアス線を介して前記各変換部に印加する電圧の電圧値を制御して前記各抵抗スイッチを低抵抗の状態に切り替えて前記各読み出し回路にそれぞれ前記画像データを読み出させる処理を、印加する電圧の電圧値を切り替える前記バイアス線をシフトさせながら行わせることを特徴とする請求の範囲第1項に記載のイメージセンサー。 The control means includes
A voltage value of a voltage applied to each conversion unit from each switching driver via each bias line is controlled to switch each resistance switch to a high resistance state, and generated in each conversion unit by light irradiation. Transition to a charge accumulation state in which charges are accumulated in each of the conversion units,
After the charge accumulation state, when the image data is read out, the voltage value of the voltage applied from the switching driver to the converters via the bias lines is controlled to reduce the resistance switches. 2. The process of switching to a resistance state and causing each of the readout circuits to read out the image data is performed while shifting the bias line for switching the voltage value of the applied voltage. The image sensor described in 1. - 前記各変換部では、前記第1電極と、前記抵抗スイッチの2つの電極のうちの一方の電極とが共通の電極とされることにより、前記変換部の第1電極と前記抵抗スイッチとが電気的に接続するように設けられていることを特徴とする請求の範囲第1項または第2項に記載のイメージセンサー。 In each of the conversion units, the first electrode and one of the two electrodes of the resistance switch are a common electrode, whereby the first electrode of the conversion unit and the resistance switch are electrically connected. The image sensor according to claim 1, wherein the image sensor is provided so as to be connected to each other.
- 前記各変換部では、前記第1電極と、前記抵抗スイッチの2つの電極のうちの一方の電極とが直接接続されることにより、前記変換部の第1電極と前記抵抗スイッチとが電気的に接続するように設けられていることを特徴とする請求の範囲第1項または第2項に記載のイメージセンサー。 In each of the conversion units, the first electrode and one of the two electrodes of the resistance switch are directly connected to electrically connect the first electrode of the conversion unit and the resistance switch. The image sensor according to claim 1, wherein the image sensor is provided so as to be connected.
- 前記変換部と前記抵抗スイッチとが積層させて形成されていることを特徴とする請求の範囲第3項または第4項に記載のイメージセンサー。 The image sensor according to claim 3 or 4, wherein the conversion unit and the resistance switch are laminated.
- 前記抵抗スイッチは、高抵抗の状態における抵抗値と低抵抗の状態における抵抗値との比が105以上とされていることを特徴とする請求の範囲第2項から第5項のいずれか一項に記載のイメージセンサー。 The resistive switch is any one of claim 2 of the fifth term of the ratio of the resistance value in the state of the resistance value and a low resistance in a state of high resistance, characterized in that there is a 10 5 or more The image sensor according to item.
- 前記抵抗スイッチとして、ユニポーラ型の抵抗スイッチまたはバイポーラ型の抵抗スイッチが用いられており、
前記制御手段は、前記画像データの読み出し処理の際には、前記バイアス線ごとに、前記切替ドライバーから前記各バイアス線を介して前記各変換部に印加する電圧の電圧値を下げることにより前記抵抗スイッチに印加される電圧の電圧値を低下させて、前記抵抗スイッチを高抵抗の状態から低抵抗の状態に切り替えることを特徴とする請求の範囲第2項から第6項のいずれか一項に記載のイメージセンサー。 As the resistance switch, a unipolar resistance switch or a bipolar resistance switch is used,
In the reading process of the image data, the control means reduces the voltage value of the voltage applied to each conversion unit from the switching driver via the bias line for each bias line. The voltage value of the voltage applied to the switch is lowered to switch the resistance switch from a high resistance state to a low resistance state, according to any one of claims 2 to 6. The image sensor described. - 前記制御手段は、前記バイアス線ごとの前記画像データの読み出し処理が終了すると、前記切替ドライバーから前記各バイアス線を介して前記各変換部に印加する電圧の電圧値を上げることにより前記抵抗スイッチに印加される電圧の電圧値を上昇させて、前記抵抗スイッチを低抵抗の状態から高抵抗の状態に切り替えることを特徴とする請求の範囲第7項に記載のイメージセンサー。 When the reading process of the image data for each of the bias lines is completed, the control unit increases the voltage value of the voltage applied from the switching driver to the conversion units via the bias lines. The image sensor according to claim 7, wherein the resistance switch is switched from a low resistance state to a high resistance state by increasing a voltage value of an applied voltage.
- 請求の範囲第1項から第8項のいずれか一項に記載のイメージセンサーと、
放射線が照射されると、放射線を光に変換して前記各変換部に出力するシンチレーターと、
を備えることを特徴とする放射線画像撮影装置。 The image sensor according to any one of claims 1 to 8,
When irradiated with radiation, a scintillator that converts the radiation into light and outputs the light to each of the conversion units;
A radiographic imaging apparatus comprising:
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