JP3447947B2 - X-ray imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a medical X-ray diagnostic apparatus.
The present invention relates to an X-ray imaging device used for a device or the like. [0002] 2. Description of the Related Art In recent years, in the medical field, rapid treatment has been performed.
Database of patient medical data to ensure
Are moving in the right direction. X-ray image data
There is a request to create a database, and digital
Is desired. In a medical X-ray diagnostic apparatus, a conventional silver halide
Have been shot using a digital camera
After developing the film, take the scanner again.
And so on, which requires time and effort.
Recently, using a CCD camera of about 1 inch, direct image
Has been realized. But the example
For example, when taking pictures of the lungs, the area of about 40cm x 40cm
An optical device for focusing light is required for shooting.
Therefore, the size of the apparatus has become a problem. As a method for solving these problems, a-
SiTFT (amorphous silicon thin film transistor)
X-ray imaging device (hereinafter also referred to as X-ray flat panel detector)
(For example, USP 468948).
7). The configuration of this X-ray flat panel detector will be described below with reference to FIG.
Tell you. In FIG. 8, pixels ei, j (i = 1 to 2)
000, j = 1 to 2000) is a-Si TFT10
1. It is composed of a photoelectric conversion film 102 and a pixel capacitor 103,
These pixels are an array of 2000 horizontal x 2000 vertical
(Hereinafter referred to as a TFT array). Photoelectric change
A bias voltage is applied to the exchange film 102 by a power supply 104.
Is done. The a-Si TFT 101 scans with the signal line 106.
The scanning line driving circuit (shift
On / off is controlled by the transistor 107. signal
The end of the line 106 is connected to an amplifier 108 for signal detection.
ing. When light is incident, a current is applied to the photoelectric conversion film 102.
As a result, charges are accumulated in the pixel capacitor 103. Scan line drive
The scanning line is driven by the circuit 107 and connected to one scanning line.
Turn on all the a-Si TFTs 101
The transferred charge is transferred to the amplifier 108 side through the signal line 106.
Sent. The amount of charge varies depending on the amount of light entering the pixel.
As a result, the output amplitude of the amplifier 108 changes. Amplifier 108
A / D conversion of the output signal of
Can be For an X-ray flat panel detector using an a-Si TFT
Converts the incident X-rays into visible light with a phosphor,
Indirect conversion method that converts the light that has fallen into charges with the photoelectric conversion film of each pixel
In addition to the X-ray flat panel detector described above, X-rays incident on pixels are directly charged
There is a direct conversion type X-ray flat panel detector that converts the light into an X-ray. Directly
Conversion X-ray flat panel detector and indirect conversion X-ray flat panel detector
And the magnitude of the bias applied to the charge conversion film
The way of calling is different. In the case of the indirect conversion method, only the photoelectric conversion film is used.
When a negative bias of several volts is applied, light enters the photoelectric conversion film and
When it comes, each pixel is provided in parallel with the photoelectric conversion film.
Capacity (storage capacity, Cst) and capacity Cs of photoelectric conversion film itself
Charge is stored in i. In this case, the voltage applied to Cst is
The maximum number of bias voltages applied to the photoelectric conversion film
About V. On the other hand, in the direct conversion method, an X-ray
The load conversion membrane and Cst are connected in series,
Then, a high bias of several kV is applied. X-rays incident on pixels
Then, the charges generated in the X-ray charge conversion film are accumulated in Cst.
However, when the incident X-ray dose is excessive, it is accumulated in Cst.
Charge is increased and the maximum voltage of several kV is applied to Cst
Of TFT and Cst provided as a switch of the pixel.
There is a risk of breaking the insulation. Therefore, direct conversion
In the system, excessive voltage is not applied to TFT and Cst
To avoid this, if X-rays enter the pixel excessively,
The required charges are stored in Cst and the remaining charges are stored.
The load is a protection circuit consisting of a-Si TFT provided for each pixel.
And emitted outside the pixel. FIG. 7 shows a pixel area of a conventional X-ray flat panel detector.
FIG. 3 is a diagram showing a cross-sectional configuration of FIG. In FIG. 7, on a glass substrate 121,
Gate electrode 122, scanning line 123, storage capacitor line (storage capacitor
Amount of electrode portions) 124 are formed, and these
A gate insulating film 125 is formed on the upper layer side. this
The channel of the a-Si TFT is formed on the gate insulating film 125.
An a-Si film 126 serving as a formation layer is formed.
A silicon film as a stopper insulating film (not shown)
A nitride film is formed. on both ends of the a-Si film 126
In the corresponding region, n serving as a source / drain⁺a-S
An i film (not shown) is formed.⁺a-Si
The source electrode 128 and the drain electrode 127 are connected to the film
Have been. The drain electrode 127 has the same process in the same layer.
Are connected. these
An insulating film 130 is formed on the upper layer side.
The pixel electrode is formed on the insulating film 130 through the opening formed in the substrate.
131 are formed. On the upper layer side of the pixel electrode 131
An X-ray charge conversion film 132 is formed, and further thereon
A part electrode 133 is formed. In the above conventional configuration, the signal line 129 and the pixel
An insulating film between the electrode 131 and the X-ray charge conversion film 132
130 has only one layer interposed. Therefore, between the two
Large noise may be caused by the capacitive coupling of
There is. Further, the signal line 129 and the lower capacitor line 124
Only the insulating film 125 is interposed between them. But
Therefore, even in this part,
Therefore, a large noise component may be generated. Signal line
Noise components are amplified by the detection amplifier.
It is difficult to obtain accurate imaging results (diagnosis results).
Was. [0013] As described above,
In a conventional X-ray imaging apparatus, the distance between a signal line and another conductive region is large.
Large noise may be caused by the capacitive coupling of
To obtain accurate imaging results especially for weak signals.
Was difficult. The present invention has been made to solve the above-mentioned conventional problems.
The capacitance cup between the signal line and other conductive areas
Reduces ringing and results in less noisy imaging
It is an object to provide a possible X-ray imaging device. [0015] An X-ray imaging apparatus according to the present invention
Is the X that is incident on the detection unit composed of a plurality of arranged pixels.
A conversion film that converts lines into electric charges, and a conversion film
A storage capacitor for storing the charge converted by the conversion film;
The storage capacity is provided corresponding to this storage capacity.
The read out charge is read out from the thin film provided below the conversion film.
A film transistor and this thin film transistor
A scan line that supplies a signal for controlling the off state, and the scan line
Thin film transistor turned on by signal from line
Before the charge stored in the storage capacitor is sent out through the
A signal line provided below the thin film transistor;
A first insulating film serving as a gate insulating film of the thin film transistor
Provided below and above the signal line.
A second insulating film, an upper layer side and in front of the first insulating film;
A third insulating film provided below the conversion film.
(Claim 1). According to the first aspect of the present invention, the signal line and the variable
In addition to the first insulating film (gate insulating film),
The second insulating film (lower insulating film) and the third insulating film (upper insulating film)
Insulating film). Therefore, the total thickness of the insulating film
Thickness can be increased (total capacity can be reduced
Low capacitance coupling between the signal line and the conversion film
(Pixel electrode and signal line overlap)
The coupling with the pixel electrode can be reduced.
Can reduce the noise component of the signal line
You. In addition, a cup between the signal line and the scanning line or storage capacitor line
Noise due to the ring can be reduced. As described above, according to the present invention, signal lines and
Reducing capacitive coupling between other conductive regions
To obtain a detection signal with a high S / N ratio.
High performance of medical X-ray diagnostic equipment, etc.
It works. [0018] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
It will be described with reference to FIG. (First Embodiment) 1 and 2 show an X-ray detection device according to a first embodiment.
(In this example, the indirect conversion type is shown.)
FIG. 1 is a plan view showing a configuration corresponding to the configuration.
FIG. 2 is a sectional view taken along the line A-A ′ in FIG.
FIG. 1 and 2, on a glass substrate 11
Has a signal line 12 formed therein.
Silicon as a lower insulating film on the formed glass substrate
An oxide film 13 is formed. This silicon oxide film 13
Above is the gate voltage of the a-Si TFT 1 for reading out the electric charge.
The poles 14, the scanning lines (address lines) 15 and the storage capacitance lines (storage lines)
16 (including the electrode portion of the storage capacitor) in the same layer.
And a gate insulating film 17 is formed on the upper layer side.
Have been. On this gate insulating film 17, a-SiT
An a-Si film 18 serving as a channel forming layer of the FT 1 is formed.
A stopper insulating film (shown in FIG.
), A silicon nitride film is formed. a-Si
Source / drain regions are formed in regions corresponding to both ends of the film 18.
N⁺An a-Si film (not shown) is formed.
n⁺The source electrode 21 and the drain electrode 2 are formed on the a-Si film.
0 is connected, and the drain electrode 20 is connected to the connection electrode 19.
Is connected to the signal line 12 via the. An upper insulating film 17 is formed on the gate insulating film 17.
(A passivation film or the like) 22 is formed, and
The upper insulating film 2 through the connection hole provided in the upper insulating film 22
2, a pixel electrode 23 is formed. Note that here
The storage capacitor line 16, the pixel electrode 23, and the
Although the storage capacitor is formed by the edge film, the pixel electrode 23
The source electrode 21 is extended instead of
Electrode. A-S on the upper layer side of the pixel electrode 23
The photoelectric conversion film 24 using i is formed, and further thereon
Has an upper electrode 25 formed thereon. Hereinafter, the structure shown in FIGS. 1 and 2 will be manufactured.
Will be described. First, a signal line 12 is formed on a glass substrate 11.
And MoW or MoTa in 3000 Angstrom
To achieve. Subsequently, plasma CVD was used as the lower insulating film.
More SiO_TwoDeposit film 13 at 6000 Å
You. Next, a MoW film is deposited at 2500 Å.
This is patterned to form a gate electrode 14, an address
The line 15 and the capacitance line 16 are formed. Next, SiO 2 is used as the gate insulating film 17._Twofilm
3500 Å, Si_ThreeN_Four500 membrane
To form a stacked layer. On this gate insulating film 17
Then, an a-Si film 18 is formed to a thickness of 500 Å.
In addition, Si as a stopper insulating film_ThreeN_Four20 membranes
00 Å is deposited. Then, for backside exposure, etc.
After forming a resist pattern,
Gate by performing etching using
Si only on top_ThreeN_FourLeave the membrane. Next, to plasma CVD
More n⁺a-Si film is formed to a thickness of 500 Å
You. Then, this n⁺a-Si film and a-Si film
To leave the a-Si film in an island shape. Then, Mo
500 angstroms, 3500 angstroms of Al
By forming a layer stack and patterning it.
The source electrode 21 and the drain electrode 20 of the Si TFT
Form. Next, as the upper insulating film 22, Si_ThreeN
_Four2000 Angstrom film and acrylic exposure
Form 3 μm of resin, Optmer PC or BCB
Then, a contact hole is formed. Next, this insulating film
A pixel electrode 23 is formed on ITO 22 by using ITO. That
Thereafter, an a-Si photoreceptor film 24 is formed, and A
1 forms the upper electrode 25. The structure shown in FIGS. 1 and 2 is adopted.
Accordingly, between the signal line 12 and the photosensitive film 24,
Lower insulating film 13, gate insulating film 17, and upper insulating film
22 will intervene. Therefore, the total thickness of the insulating film
The signal line and pixel electrode and photoconductor can be made thicker
Significantly reduce noise due to coupling with the membrane
be able to. In particular, when a high voltage of several kV is applied,
For upper body electrode and pixel electrode whose potential is increased by strong X-ray
Signal line noise can be reduced. In addition, running with the signal line 12
The coupling between the scanning line 15 and the storage capacitance line 16
Noise can be significantly reduced. In addition, signal line
The pixel electrode 23 is also formed on the
Since the aperture ratio can be improved, for example, by about 15%,
The ratio of the signal current can be increased by about 15%, and S
It is possible to further improve the / N ratio. (Second Embodiment) 3 and 4 show an X-ray detection device according to a second embodiment.
(In this example, the direct conversion type that converts X-rays
Shown. ) Shows a configuration corresponding to one pixel.
FIG. 3 is a diagram showing the planar configuration, and FIG.
FIG. 3 is a diagram illustrating a cross-sectional configuration at A ′. 3 and 4, on a glass substrate 31
Are formed with a signal line 32 and a storage capacitor line 33,
On the glass substrate on which the signal 32 and the like are formed, the lower layer
A silicon oxide film 34 is formed as an edge film. this
A-SiT for charge reading is formed on the silicon oxide film 34;
The source electrode 37 and the drain electrode 36 of FT1 are formed.
(Source / drain of protection a-Si TFT2)
The electrodes are also formed at the same time.)
The source electrode 37 of the iTFT1 is connected to the upper electrode of the storage capacitor.
The drain electrode 36 extends through the connection electrode 35
Line 32 is connected. Also, on the lower insulating film 34
Is a-Si TFT which becomes a channel forming layer of a-Si TFT.
A film 38 is formed, and a gate
An insulating film 39 is formed. On this gate insulating film 39
The gate electrode 4 of the charge readout a-Si TFT 1
0, protection a-Si TFT2 gate electrode, scanning line (A
Dress line) 41, power supply line (bar) for protection a-Si TFT2.
Ias line) 42 is formed. Further, on the upper layer side, upper insulating films 43, 4
4 are formed on the insulating films 43 and 44.
The pixel electrode 45 is formed on the insulating film 44 through the connection hole.
I have. X-ray using a-Se on the upper layer side of the pixel electrode 45
A charge conversion film 46 is formed, and an upper electrode is further formed thereon.
47 are formed. Hereinafter, the structure shown in FIGS. 3 and 4 will be manufactured.
Will be described. First, the signal lines 32 and
MoW or MoTa is turned on for 3000 as the capacitance line 33
Gustrom formation. Subsequently, the lower insulating film 34 is formed.
By plasma CVD_Two6000 Å membrane
Trom deposited, this SiO_TwoContact hole in film
Form. Then, MoW was 2,500 Å
By forming a film and patterning it, a-Si
Forming a source electrode 37 and a drain electrode 36 of the TFT;
At the same time, an upper electrode of the storage capacitor is formed. further,
PH for source and drain electrodes_ThreePlasma treatment
Do. Next, the a-Si film 38 is coated with 1000 angstrom.
In this case, the source / drain regions
PH_ThreeN by plasma treatment⁺a-Si film is formed
It is. Next, silicon nitride is used as the gate insulating film 39.
An oxide film is formed to 3000 Å. Then, A
1 Angstrom alloy is formed to form a pattern
The gate electrode 40, the address line
41, forming a bias line 42 of the protective a-Si TFT
You. On top of this, SiN is used as an upper insulating film._xMembrane (Pashibe)
Solution film) 43 to 3000 angstroms, and
Acrylic photosensitive resin, Optmer PC or BCB (interlayer
(Insulating film) 44 is formed to a thickness of 3 μm,
To form Next, the pixel electrode 45 is formed by ITO.
After that, an X-ray charge conversion film 46 using Se is formed, and
Then, an upper electrode 47 is formed of Al thereon. The structure shown in FIGS. 3 and 4 is adopted.
Thus, the signal line 32, the pixel electrode 45, and the X-ray charge
The lower insulating film 34 and the gate insulating
The film 39 and the upper insulating films 43 and 44 are interposed.
You. Therefore, the signal line, the pixel electrode and the X-ray charge conversion film
Noise due to coupling between
Can be. Also, the signal line 32, the scanning line 41, and the via
Noise due to coupling with the wire 42 is also reduced.
be able to. Further, the signal line 32 and the storage capacitor line 33
Are arranged in parallel, so that the signal line and the storage capacitor line
Noise due to coupling can also be reduced.
You. Note that the pixel electrode 45 must be formed on the signal line 32.
To improve the aperture ratio of pixels by, for example, about 15%.
Increase the ratio of signal current by about 15%
And it is possible to further improve the S / N ratio.
You. [0034](First reference example) FIG. 5 and FIG.First reference exampleOf X-ray detection device according to
FIG. 5 shows a configuration corresponding to pixels.
FIG. 6A shows a plan configuration, and FIG.
FIG. 6B is a sectional view taken along line B-B ′ in FIG.
FIG. 3 is a diagram showing a surface configuration. In this example, the capacitance line is
Arranged in parallel to reduce stray capacitance due to capacitance lines.
You. Note that in the examples shown in FIGS.
A-Si TFT1 for taking out, a-SiTFT2 for protection,
Elementary electrode 63, signal line 61, scanning line 55, storage capacitor line 5
2. The bias line 56 of the protection a-Si TFT is drawn.
However, actually, the upper layer of the structure shown in FIG.
Electrodes, X-ray charge conversion films, X-ray charge conversion film electrodes, etc.
Has been established. The function will be briefly described.
Consists of an insulating film interposed between the pixel electrode 63 and the capacitance line 52
Generated by the X-ray charge conversion film by the incidence of X-rays
The stored charge is stored in the storage capacitor, and the read TFT 1
When the voltage reaches a certain level that does not cause dielectric breakdown,
The charge flows out of the pixel from the protection TFT 2 and is read out.
High voltage is no longer applied to TFT1 and storage capacitor
ing. The charge outflow path at this time is the bias line 56.
By setting the potential of the bias line 56, the protection T
The starting voltage of charge outflow from FT2 can be changed
You. The charge stored in each pixel scans the scanning line 55
Thus, each TFT 1 of the pixel on the scanning line
Is turned on to be taken out to the signal line 61. Taken out
The charge is transferred to an amplifier (not shown). Next, a more detailed configuration of this embodiment will be described.
You. On the glass substrate 51, a storage capacitance line 52 is formed.
And an insulating film 53 is formed thereover.
I have. However, the contact part of the voltage supply line (not shown)
In this case, the insulating film 53 is removed. Insulation
On the film 53, the gate voltage of the a-Si TFT 1 for reading is
Pole 54, gate electrode of a-Si TFT2 for protection, scanning line
55, Power supply line (bias line) for protection a-Si TFT2
56 are formed, and a drawer pad (not shown)
It is formed at the same time. On top of these are the gate insulation
A film 57 is formed. However, the drawer pad and
For through holes of protective transistors, etc.,
The gate insulating film has been removed. On the gate insulating film 57, a pixel electrode 63 is formed.
In the pixel excluding the readout TFT1 and the protection TFT2
Is formed. For the TFT 1 for reading,
An a-Si film 58 as an upper layer
Silicon nitride film 59 for the pad, n⁺a-Si film 60
Formed, n⁺a source electrode on the a-Si film 60
62 and a drain electrode 61 are formed.
FT has the same configuration)
Depending on the metal used for the rain electrode, the source and drain
The pixel electrode 63 and the signal line
61, a drawing pad (not shown), a voltage supply line (FIG.
(Not shown) are also formed. Further, on the upper layer side, a passivation film, X
Although a linear charge conversion film, an upper electrode, etc. are formed,
Omitted. According to this embodiment, the signal line and the storage capacitor line are flat.
Since they are arranged in rows, signal lines and storage capacitance lines intersect
Can reduce the effects of coupling.
Thus, noise of the signal line can be reduced. Note that, in addition to the examples shown in FIGS.
The pixel electrode extends above the protection transistor bias line 56.
It is also conceivable that the pole 63 is formed. By doing this
Thus, the effective area of the pixel can be made wider. Also,
In the examples shown in FIGS. 5 and 6, the signal lines are provided on the upper layer side.
However, if it is parallel to the capacitance line, it may be provided on another layer. Ma
Also, connect the bias line of the protection transistor in parallel with the signal line.
Coupling between signal line and bias line
Can be reduced. Further, in the example shown in FIGS.
Example of using one TFT as a TFT
However, two or more TFTs are arranged in series and
To reduce the leakage current of the protection TFT
It is also conceivable to take countermeasures against damage. Also, the arrangement of TFT
The position can also be appropriately changed within the pixel. Note that the aboveFirst and second embodiments, and
First reference exampleAt (described laterReference exampleBut basically
Same), gate electrode, source / drain electrode, scanning line,
Metals used for signal lines, capacitance lines, bias lines, pixel electrodes, etc.
For example, Ti, Cr, Ta, Mo, MoW, M
oTa, Al, ITO, Al alloy (especially Al-Zr,
Al-Nd, Al-Y alloy), a laminated structure of these metals
And so on. For gate electrodes and scanning lines, MoW or
MoTa is formed by tapering the gate of the TFT.
Since it is possible to perform
Can be formed so that the insulating film does not break
Wear. When an Al alloy is used, only the Al
Hillocks generated in the high-temperature process
Therefore, it is preferable when the size of the X-ray detector is increased.
It can be said that it is a material. The same applies to the metal forming the storage capacitance line.
MoW, MoTa, or Al alloy
Preferably. Also, for metals used as signal lines
In particular, Al or Al is used because low resistance is desired.
It is preferable to use a laminated structure, an Al alloy, or the like. The gate insulating film is made of SiO_Two, SiN
_x, SiO_xN_yHowever, with these laminated structures,
Is also good. As passivation film and interlayer insulating film, inorganic
As an insulating film, for example, SiO_TwoFilm and SiN_xFilm, organic insulation
As a film, for example, polyimides, BCB, optomer, black
Resist, fluorine resin, etc. can be used.
You may. Also, these resins are more photosensitive
This is preferable because the formation of the layer is easy and the number of steps is reduced. As a TFT, an inverted staggered edge is used.
Ching stopper type, back channel cut
-A type or the like can be used. Form TFT
In addition to amorphous silicon,
Silicon may be used, and if polysilicon is used
May form a peripheral circuit on the same glass substrate. Ma
In addition, the charge accumulated in the pixel is used for turning on / off the TFT.
Source follower principle in addition to
It is also possible to use a conventional non-destructive read method. [0048](Second reference example) FIG.Second reference exampleThe equivalent circuit structure of
FIG.This reference example is also the first reference example.the same as,
The capacitor lines are arranged in parallel with the signal lines. In FIG. 13, reference numeral 201 denotes a-
Si TFT, 202: X-ray charge conversion film, 203: protection
Iodine (for example, composed of a-Si TFT for protection)
), 204 is a storage capacity, 205 is a scanning line, and 206 is a signal.
No., 207 is a storage capacity line, 208 is a-SiT for protection
FT bias line, 209 is high voltage to X-ray charge conversion film
Supply lines.First
Reference exampleAnd so on. 210 is a detection amplifier, 21
1 is a signal detection circuit constituted by a plurality of detection amplifiers 210
(Consisting of an integrated circuit). In the configuration shown in FIG.
The signal line 206 and the capacitance line 207 are wired in parallel to the input section.
Have been. Each signal line 206 is connected to a detection
Connected to one input terminal of the output amplifier 210
207 is connected to the other input terminal of the detection amplifier 210.
ing. With such a configuration, the signal line 206 and the capacitor line
Since the potential difference from 207 is always constant, the voltage of the capacitance line
The increase in noise due to fluctuations is suppressed,
Images can be detected. In FIG. 13, the signal line 206 and the capacitance line
207 is schematically shown on the same pattern,
Connection between the line 206 and the capacitance line 207 and the signal detection circuit 211.
Followed by COG (Chip On Glass), TC
P (Tape Carrier Package), F
PC cable connection, etc. are conceivable.
The above configuration can be realized, and the same effects can be obtained.
Can be. FIG.Second reference exampleFor another example of
It is a figure showing the equivalent circuit composition. The configuration shown in FIG.
The components corresponding to the components have the same numbers.
(The same applies to other figures).This reference exampleAlso in FIG.Reference exampleAs well as
The quantity lines are arranged in parallel with the signal lines. In the example shown in FIG.
In the wiring stage up to, a plurality of capacitance lines 207 are put together,
The input terminal of the detection amplifier 210 has a capacitance line after being put together.
Is entered. In the example of FIG.
Path (eg, one integrated circuit chip) 211
Each capacitor line connected to each pixel is grouped together, and other
Each capacitance line connected to each pixel detected by the signal detection circuit is other
Of the detection circuits. The place to put together the capacity lines
The position is preferably outside the array area where the pixels are arranged.
Good. In the example of FIG. 14, the capacitance line 207 is connected to the signal detection circuit 2
Before inputting the signal to the signal detection circuit 211, the signal detection circuit 211
After input to the detection amplifier 210
You may do so. Also in this example, the signal line 206 and the capacitance line 2
07 is always constant, the voltage change of the capacitance line
The increase in noise due to motion is suppressed, and good
An image can be detected. In FIG. 14, as in the example of FIG.
Line 206 and capacitance line 207 are schematically shown on the same pattern.
Signal detection with the signal line 206 and the capacitance line 207
COG (Chip On G) is connected to the circuit 211.
las), TCP (Tape Carrier Pa)
cage), connection with FPC cable, etc.
In each case, the above configuration can be realized.
Various effects can be obtained. [0056](Third reference example) FIG.Third reference exampleShows the equivalent circuit configuration for
FIG.This reference exampleIs based on the protection diode 203.
A bias line 208 for applying a quasi-potential has a plurality of pixels arranged.
Grouped outside the array area and provided outside the array area
Connected to the power supply 231. When the protection diode exceeds a certain voltage, it turns off.
Operation, and the excess charge is stored.
Has the function of preventing the TFT from being destroyed by the above. Security
When the protection diode is turned on, current flows through the bias line.
Release the charge out of the array, but the resistance of the bias line
To avoid problems such as fluctuation of reference potential and heat generation due to
In addition, the resistance of the bias line must be as low as possible. Therefore, in this example, as shown in FIG.
The connection with the external power supply 231 is taken at multiple points.
You. The wiring width of the bias line 208 is limited to about several 100 μm.
Low resistance by using parallel wiring.
You. The scanning line drive IC 232 is connected to the external power supply 231.
By taking from the implemented TCP 233, special
Can be connected without using any cables or pads.
You. By using the configuration of this embodiment, the protection die
Suppress fluctuations in reference potential and heat generation due to the operation of the ode
Can prevent the TFT array from being destroyed.
Can be. [0060](Fourth reference example) FIG.Fourth reference exampleShows the equivalent circuit configuration for
FIG.This reference exampleIs capacitively coupled to the signal line
This is to reduce the coupling capacitance with other wirings in terms of a circuit.
Change the potential of the other wiring by the same amount as the potential change of the signal line.
By this, the potential difference between both ends of the coupling capacitance becomes zero
Charge flowing into or out of the coupling capacitance
Charge can be eliminated. Therefore, in effect
It is possible to make it equivalent to the extremely small combined capacity.
Wear. This reduces the parasitic wiring capacitance of the signal line,
Noise due to line capacitance (almost proportional to wiring capacitance)
Can be extremely small. Hereinafter, a specific description will be given with reference to FIG.
You. In this example, the signal line has a high input impedance buffer.
Amplifier, and the output of the amplifier
It controls the source. Here is the capacitance with the scanning line
Applies to gate driver ICs to reduce coupling
The gate driver IC is turned off by the output of the buffer amplifier.
The potential is controlled. OFF potential for TFT array operation
Control the off-potential because most of the time is
It is effective. First, the signal potential of the signal line is
Amplifier 2 that receives the output and creates the gate-off potential
23 and add. In other words, the original gate-off
Since the potential obtained by adding the signal line potential to the
The effects described above can be obtained. Frequency band of each amplifier
Is equivalent to the frequency band of the noise to be reduced.
It is preferable to have. In this case, the connection between the signal line and the gate line is performed.
Although the example of reducing the capacitance has been described,
Wiring with large coupling capacitance such as ias wire
It is equally applicable. [0064](Fifth reference example) FIG. 9 shows an X-ray imaging apparatus (direct conversion type X-ray imaging apparatus).
FIG. 10 is a diagram showing the entire configuration, and FIG.
FIG. 3 is a diagram illustrating a cross-sectional configuration of a SiTFT array unit. Here, as an example of an a-Si TFT, a reverse switch is used.
1 shows a structure of a tag type TFT. In the description, the pixel
The TFTs in the figure are described as TFTs for charge reading
However, in addition to the charge reading TFT, a high-voltage protection
Even if there is a TFT for the diode,
TFT and TFT for high voltage protection diode are in the same layer
, It can be explained in the same way as in the case of this example.
You. FIG. 9 shows an image pickup apparatus using an a-Si TFT.
FIG. 2 is an overall configuration diagram. The X-rays emitted from the X-ray source 151
A-SiTFT imaging device 1 passing through the subject 152
It is incident on 53. a-SiTFT imaging device 153
Is a secondary layer on the lower layer side of the X-ray charge conversion film using a-Se or the like.
An array portion in which the originally arranged a-Si TFTs are formed,
Scan line drive circuit to turn on / off a-Si TFT, test
X-rays that have passed through the body 152 are converted into analog
It is composed of a signal detection circuit and the like for converting the air signal. The converted analog signal is A /
Digitally converted by the D conversion unit 157,
Stored in the memory 158. Image memory 158 has one
Or data for several images can be stored.
Data to the address specified by the control signal from
Next memorize. In the arithmetic processing unit 159, the image memory 15
8 and take out the operation, and return the operation result
Input to the memory 158. Computed image memo
The data of the file 158 is analyzed by the D / A conversion unit 160.
Is converted into an X-ray image and displayed on the monitor 161 as an X-ray image.
It is. The charges accumulated in the pixels are detected as shown in FIG.
The signal is transferred to the amplifier 241, but the detection amplifier 241 is
It is anti-input. Therefore, it is a weak disturbance
Also affects the output, causing image quality degradation. Disturbance factors
And noise from the scanning line 205. Scan lines are
The capacitor 242 is formed by intersecting with the signal line 206 via the insulating film.
However, the power supply potential of the scanning line drive circuit fluctuates.
Then, a charge appears in the capacitance 242 at the intersection, and this charge is also detected.
This is transferred to the output amplifier 241. Accumulated in pixels
Charge on the order of
Is a major factor in image quality deterioration. Hereinafter, the manufacturing process of the array portion will be described with reference to FIG.
explain about. The Mo is placed on a silicon wafer or a glass substrate 71.
After depositing a refractory metal such as Ta or MoW,
Pattern the gate electrode 72, the scanning line 73,
A pole (storage capacitor electrode) 74 is formed. Next, the gate electrode 7
2. On the structure where the scanning lines 73 and the auxiliary electrodes 74 are formed
Deposit gate insulating film 75 (SiOx or SiNx)
You. Further, an etch made of a-Si film 76 and SiNx
The insulating film 77 for the stopping stopper is deposited, and these are patterned.
To run. For a-Si film 76 and etching stopper
The insulating film 77 is usually formed only on the TFT, but in this example,
At the intersection of the scanning line 73 and the signal line 78 in addition to the TFT section
Also formed an a-Si film 76 and an etching stopper layer 77
Structure. Next, the TFT of the TFT is made of a metal such as Al or Mo.
Source electrode 79, drain electrode 80, and signal line 78
To form After forming the signal line 78, the organic film 81 is formed.
Formed on the organic film 81, such as Al, Al alloy, Ti, etc.
The pixel electrode 82 is formed of metal or ITO, and the pixel electrode 8 is formed.
X-ray charge conversion film 83 (a-
(Formed of Se or the like). Finally, X-ray charge conversion
A high voltage supply electrode 84 is formed on the film 83. The signal line of the X-ray imaging apparatus having the above configuration
The scanning line intersection capacitance Cs-g is as shown in FIG.
In addition to the capacitance C1 of the insulating film 75, an a-Si film 76
And the capacitance C2 of the etching stopper insulating film 77.
 , C3 are connected in series. Where
In the case of only the edge film 75 (FIG. 11A),
A-Si film 76 and insulating film 7 for etching stopper
7 (FIG. 11b).
Calculate. Here, for example, both the scanning line width and the signal line width
10 μm (intersection area S = 100 μm^Two), Insulating film 75
Of 0.3 μm, relative dielectric constant ε1 of 5, a-Si
The film 76 has a thickness d2 of 50 .mu.m, a relative dielectric constant .epsilon.
The thickness d3 of the insulating film 77 for the etching stopper is set to 0.3 μm.
Assuming that m and the relative permittivity ε3 are 6, the field shown in FIG.
The capacitance C at the intersection is C = C1 = ε1 ε0 S / d1 = 5x8.854x10^-12x (10x10^-6)^Two/0.3x10^-6= 14.8 [f
F] Is calculated. When the number of scanning lines is 1,000,
Means that there is an intersection capacitance of 14.8 [pF].
Therefore, even if the power supply potential of the scanning line driving circuit fluctuates by 1 mV,
An electric charge of 4.8 [fC] is generated on the signal detection circuit side.
U. The charge stored in the pixel is of the same order.
Charge from the scanning line intersection is a major cause of image quality degradation.
It is a factor. On the other hand, as shown in FIG.
A-Si film 76 on top 75 and insulation for etching stopper
When the film 77 is further deposited, the series connection of each insulating film capacitance is performed.
Connection, and the intersection capacitance C ′ becomes C '= C1 C2 C3 / (C2 C3 + C3 C1 + C1 C2
 ) = Ε1 ε2 ε3 ε0 S / (ε2 ε3 d1 + ε3 ε1 d2
+ Ε1 ε2 d3) = 7.7 [fF] And it is reduced by about half. Therefore, the scanning line drive proportional to the intersection capacitance
The noise component from the circuit power supply is halved,
The range is improved by 6 [dB]. X-ray diagnostic equipment
In fields where a high dynamic range is required, such as
Therefore, it can be said that the structure shown in this example is very effective. Further, the a-Si film 76 and the etching
Stopper insulating film 77 is deposited at the intersection of the signal line and the scanning line.
The structure to be used is a part of the TFT manufacturing process as described above.
The structure is used. This makes the process complicated
Noise reduction without the need for
There are benefits. In the above example, the storage capacitor line 74 runs
It is formed on the same layer as the scanning line 73 and the gate electrode 72.
However, it may be formed on another layer via an insulating film. [0078](Sixth reference example) FIG.Sixth reference exampleTFT X-ray imaging device
It is a figure showing the plane composition of a ray part. The configuration shown in FIG.
The same reference numerals are given to the components corresponding to the
A detailed description is omitted. In the description, the TFT in the pixel is
Although the description has been made with reference to the TFT for reading charges,
TF for high voltage protection diode in addition to TFT for load readout
Even if there is T, the charge reading TFT and high voltage
The protection diode TFT is formed on the same layer.
Therefore, it can be explained similarly to the case of this example. In FIG. 12, a scanning line 73 is a signal line 78.
The wiring width at the part that intersects with the
ing. Here, the wiring width of the signal line 78 is Ws, and the signal line 7 is
8, the wiring width of the scanning line 73 other than the intersection with Wg is Wg, and the signal line is
The wiring width of the scanning line 73 at the intersection with 78 is n × Wg
(0 <n ≦ 1)
To consider. If the width of the scanning line 73 is always constant,
Difference capacitance Cs-g and resistance R are Cs-g = (ε × Ws × Wg) / D (1) R = (ρ × Ws) / (Wg × d) (2) It is expressed as Here, D is the thickness of the insulating film 75, and ρ is the scan.
The resistivity of the line 73 and d indicate the thickness of the scanning line 73. Next, the wiring width at the intersection with the signal line 78 is n
× Wg (0 <n ≦ 1), the intersection capacitance C′s-g
And the resistor R ' C's-g = (n * [epsilon] * Ws * Wg) / D
(1 ') R ′ = (ρ × Ws) / (n × Wg × d)
(2 ') Becomes That is, when the equations (1) and (2) are used,
The constant is equal to the time constant according to equations (1 ') and (2').
Value. Further, according to the formula (1 '), the wiring width is reduced.
As a result, the intersection capacity can be reduced. Therefore,
Noise due to fluctuations in the power supply of the scanning line drive circuit is reduced,
Can improve the dynamic range of diagnostic equipment
You. The aboveFifth and sixth reference examplesAs explained in
Then, at the intersection of the scanning line and the signal line, an a-Si film or an etching
When stacking the insulating film for the
To adopt a structure that makes it narrower than other parts
Thus, the intersection capacitance can be reduced, and
These noises can be reduced. Therefore, high dynamic range
Dynamic registration modification required for X-ray diagnostic equipment required
Become the influential method of good. Each of the above embodimentsAnd each reference exampleIn
As an X-ray charge conversion film (photoelectric conversion film), a-S
e, a-Te, PbI_TwoEtc. can be used. The embodiments of the present invention have been described above.
However, the present invention is not limited to these embodiments.
Various modifications within the scope that does not depart from the gist
It is possible to implement. [0086] According to the present invention, signal lines and other conductive regions are provided.
Can reduce the capacitive coupling between
Therefore, a detection signal having a high S / N ratio can be obtained,
It is possible to achieve higher performance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a planar configuration in a pixel region of an X-ray imaging apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram showing a cross-sectional configuration along AA ′ in FIG. 1; FIG. 3 is a diagram illustrating a planar configuration in a pixel region of an X-ray imaging apparatus according to a second embodiment of the present invention. FIG. 4 is a diagram showing a cross-sectional configuration along AA ′ in FIG. 3; FIG. 5 is a diagram showing a planar configuration in a pixel region of the X-ray imaging apparatus according to the first reference example of the present invention. FIG. 6 is a diagram showing a cross-sectional configuration along AA ′ and BB ′ in FIG. 3; FIG. 7 is a diagram showing a cross-sectional configuration in a pixel region of an X-ray imaging device according to a conventional technique. FIG. 8 is a diagram showing an equivalent circuit configuration mainly of a pixel array region of the X-ray imaging apparatus. FIG. 9 is a diagram showing an overall configuration of an X-ray imaging apparatus. FIG. 10 is a diagram showing a cross-sectional configuration in a pixel region of an X-ray imaging device according to a fifth reference example of the present invention. FIG. 11 is a diagram showing a signal line / scanning line intersection capacitance in a fifth reference example in comparison with a conventional technology. FIG. 12 is a diagram showing a planar configuration in a pixel region of an X-ray imaging apparatus according to a sixth reference example of the present invention. FIG. 13 is a diagram illustrating an example of an X-ray imaging apparatus according to a second reference example of the present invention. FIG. 14 is a view showing another example of the X-ray imaging apparatus according to the second reference example of the present invention. FIG. 15 is a diagram showing a configuration example of an X-ray imaging apparatus according to a fourth reference example of the present invention. FIG. 16 is a diagram showing a configuration example of an X-ray imaging apparatus according to a third reference example of the present invention. FIG. 17 is a diagram showing a problem of the related art. [Description of Signs] 1 ... a-Si TFT for readout 2 ... a-Si TFT for protection 11, 31, 51, 71, 121 ... substrate 12, 32, 78, 129 ... signal line 13, 34 ... lower insulating film 14, 40, 54, 72, 122 ... gate electrodes 15, 41, 55, 73, 123 ... scanning lines 16, 33, 52, 74, 124 ... storage capacitor lines 17, 39, 57, 75, 125 ... gate insulating film 18, 38, 58, 76, 126 ... Amorphous silicon films 19, 35 ... Connection electrodes 20, 36, 61, 80, 127 ... Drain electrodes 21, 37, 62, 79, 128 ... Source electrodes 22, 43, 44 ... Upper layer side Insulating films 23, 45, 63, 82, 131 ... pixel electrodes 24, 46, 83, 132 ... X-ray charge conversion films 25, 47, 84, 133 ... upper electrodes 42, 56 ... bias lines 53, 81, Reference Signs List 30 insulating films 59 and 77 stopper insulating film 60 n-type amorphous silicon films 101 and 201 a-Si TFTs for reading 102 and 202 charge conversion films 103 and 204 storage capacitors 104 power supplies 105 and 205 scanning lines 106 , 206 signal line 107 shift register 108 amplifier 151 X-ray source 152 subject 153 X-ray imaging device 157 A / D converter 158 image memory 159 arithmetic processing unit 160 D / A converter 161, an image monitor 162, a high voltage generator 163, a control unit 203, a protection diode 207, a storage capacitor line 208, a bias line 209, a high voltage supply line 210, 221, 222, 223, an amplifier 211, a signal detection circuit 224, and scanning. Line transistors 225, 226, 231 Power supply 232 IC 233 TCP

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Akira Kanno 33 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside Toshiba Institute of Industrial Science (72) Inventor Kohei Suzuki 33 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa (56) References JP-A-5-315581 (JP, A) JP-A-8-51195 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 27/14 G01T 1/24

Claims (1)

(57) [Claim 1] A conversion film for converting X-rays incident on a detection unit composed of a plurality of pixels into electric charges, and a conversion film provided for each pixel for conversion by the conversion film. A storage capacitor for storing the stored charge, a thin film transistor provided corresponding to the storage capacitor, reading the charge stored in the storage capacitor, and provided under the conversion film, and an on / off state of the thin film transistor. A signal line provided on the lower layer side of the thin film transistor, wherein a charge stored in the storage capacitor is transmitted through a thin film transistor turned on by a signal from the scanning line, A second insulating film provided below the first insulating film serving as a gate insulating film of the thin film transistor and above the signal line; X-ray imaging apparatus characterized by comprising a third insulating film provided on the lower layer side than the layer side and the converting layer.