JP2002124676A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the aperture ratio of pixels of a semiconductor device and speed up driving of the semiconductor device. SOLUTION: The semiconductor device has pixels having switching elements, control signal lines for transmitting signals for controlling the on-off of the switching elements and read signal lines for transmitting signals to be read with the switching elements set on. The switching elements are formed so as to involve spatial crossing parts of the control signal lines and the read signal lines.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device used for a digital camera, a liquid crystal display, an X-ray imaging system, and the like.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device such as an area sensor or a liquid crystal display used for a digital camera or an X-ray imaging device includes a pixel having a photoelectric conversion element and a thin film transistor or a liquid crystal element and a switching element such as a thin film transistor. Arrange two-dimensionally,
Some have a gate line for supplying a control signal to a gate electrode of a thin film transistor and a data line for outputting a signal from a source electrode of the thin film transistor.

FIG. 9 is a schematic diagram showing a configuration of a conventional area sensor. FIG. 10 is a schematic diagram of a pixel of the area sensor of FIG. FIG. 11 is a cross-sectional view illustrating a configuration of the pixel in FIG. FIG. 12 is a plan view showing the configuration of the pixel in FIG.

As shown in FIGS. 9 and 10, each pixel of the conventional area sensor includes a photodiode 7 as a photoelectric conversion element and a thin film transistor (hereinafter, referred to as "TFT") 8 as a switching element. Have. T
The source electrode 21 of the FT 8 is connected to the data lines Sig1 to N
The gate electrodes are connected to the gate lines Vg1 to VgN, respectively. The drain electrode 22 of the TFT 8 is connected to the photodiode 7 in the pixel. The bias line Vs is connected to the power supply 3.

In FIG. 9, data lines Sig1-N are routed in the vertical direction, and gate lines Vg1-N are routed in the horizontal direction. Further, each data line Sig1-N
It is connected to the reading device 1. Generally, the reading device 1 includes an amplifier, an analog multiplexer 6, and the like. On the other hand, each of the gate lines Vg1 to Ng is connected to the gate driver 2. Generally, the gate driver 2 has a shift register (not shown) and the like.

As shown in FIG. 11, the photodiode 7 includes a lower electrode 12, an n-layer 13, a semiconductor layer 14, a p-layer 15, and an upper electrode 16. The TFT 8 includes a gate electrode 17, a gate insulating film 18, a semiconductor layer 19, an ohmic layer 20, a source electrode 21, and a drain electrode 22. The wiring section includes a gate line, a gate insulating film 18, a semiconductor layer 19, an ohmic layer 20, and a data line.

Further, as shown in FIG. 12, a source electrode 21 of the TFT 8 is connected to a data line, and a drain electrode 22 is connected to one of an anode and a cathode of the photodiode 7. Further, the gate electrode is connected to the gate line. As described above, conventionally, the TFT 8 is configured to be independent, that is, one or both of the gate electrode and the source electrode 21 of the TFT 8 are provided independently of the data line and the gate line.

FIG. 13 is a schematic diagram showing the structure of a conventional liquid crystal display. FIG. 14 is a schematic diagram of a pixel of the liquid crystal display of FIG. As shown in FIGS. 13 and 14, each pixel of the conventional liquid crystal display is constituted by a liquid crystal display capacitor 10 and a TFT 8. As in the case of the above-described area sensor, the source electrode 21 of the TFT 8 is connected to the data lines Sig1 to N, and the gate electrode is connected to the gate line Vg.
1 to N respectively.

Further, one electrode of the liquid crystal display capacitor 10 and T
The drain electrode 22 of the FT 8 is mutually connected in each pixel. In this example, the data lines Sig1 to N are routed in the vertical direction, and the gate lines Vg1 to Ng are routed in the horizontal direction. Each data line Sig1-N is connected to the liquid crystal source driver 4. Generally, the source driver 4 includes a buffer amplifier, a D / A converter, and the like. Each of the gate lines Vg1 to VgN is connected to the liquid crystal gate driver 5. Generally, liquid crystal gate driver 5
Is constituted by a shift register not shown.

The pixel of the conventional liquid crystal display has the same configuration as that of the area sensor except that the photodiode 7 is replaced with the liquid crystal display capacitor 10.

As described above, the conventional area sensor,
A semiconductor device such as a liquid crystal display has a source electrode 21 and a gate electrode independent of a wiring portion. That is, the TFT 8 is provided independently of the wiring portion.

[0012]

By the way, when the aperture ratio of a pixel is high, an image has a higher definition and a higher image quality than that which is not.
High sensitivity and high resolution. Therefore, the higher the aperture ratio of the pixel, the better. The aperture ratio of a pixel is determined by the ratio of the area of the TFT of the pixel to the photoelectric conversion element or the liquid crystal display capacitance. Specifically, the aperture ratio increases as the ratio of the photoelectric conversion element or the like in the pixel increases.

However, in the conventional technique, the wiring portion and the TFT are separately formed as described above. This is because it is difficult to provide the same with the conventional exposure technology and patterning technology. For this reason, there is a limit to increasing the area of the photoelectric conversion element and the liquid crystal display capacitance in a pixel depending on the area of the TFT.

In addition, when the TFT and the wiring portion are provided independently, the parasitic capacitance of the wiring portion is increased, thereby generating noise, which may hinder a high-speed driving of the semiconductor device. However, in recent years, an exposure technique and a patterning technique have been improved, and it has become possible to provide a wiring portion and a TFT in common.

Accordingly, an object of the present invention is to increase the aperture ratio of the pixel of the semiconductor device by providing the TFT and the wiring portion in common.

Another object of the present invention is to speed up driving of a semiconductor device by providing a TFT and a wiring portion in common.

[0017]

In order to solve the above problems, the present invention provides a pixel having a switching element, a control signal line for transmitting a signal for controlling on / off of the switching element, and the switching element. In a semiconductor device having a read signal line for transmitting a signal read when turning on, the switching element is formed so as to include a spatial intersection between the control signal line and the read signal line. Features.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic diagram showing a configuration of a pixel of a semiconductor device according to Embodiment 1 of the present invention. FIG.
(A) is a top view of the pixel of FIG. FIG. 2 (b)
FIG. 3 is a cross-sectional view of the TFT 8 and the vicinity of a wiring portion in FIG.
Here, a case where an area sensor is used as a semiconductor device will be described as an example.

Each pixel of the area sensor has a photodiode 7 as a photoelectric conversion element and a TFT 8 as a switching element. Source electrode 2 of TFT8
1 is connected to the data lines Sig1 to N, and the gate electrode is connected to the gate lines Vg1 to Ng, respectively. TFT
8 is connected to the photodiode 7 in the pixel.
Is connected to

In FIG. 1, the data lines Sig1-N are routed in the vertical direction, and the gate lines Vg1-N are routed in the horizontal direction. Further, each data line Sig1-N
It is connected to the reading device 1. Generally, the reading device 1 includes an amplifier, an analog multiplexer 6, and the like. On the other hand, each of the gate lines Vg1 to Ng is connected to the gate driver 2. Generally, the gate driver 2 has a shift register (not shown) and the like. The bias line Vs is connected to the power supply 3.

As shown in FIGS. 2A and 2B, in the present embodiment, the TFT 8 is provided so as to include a spatial intersection between the gate line and the data line. The wiring section is shared. Specifically, the gate electrode is formed so as to include a portion on the gate line and in contact with a spatial intersection with the data line,
The source electrode 21 is formed so as to include a portion on the data line and in contact with the intersection.

In this embodiment, the case where the area sensor is used as the semiconductor device has been described as an example. However, the semiconductor device can be applied to a liquid crystal display by replacing the photodiode 7 with a liquid crystal display capacitor. .

(Embodiment 2) FIG. 3 is a schematic diagram showing a configuration of a pixel of a semiconductor device according to Embodiment 2 of the present invention. Generally, the ability of the TFT 8 such as the ON resistance is determined by the channel length L and the channel width W. The shorter the channel length L and the wider the channel width W, the more advantageous. Therefore, in the present embodiment, by increasing the width of the part of the gate line that contacts the spatial intersection with the data line,
The channel width W of the TFT 8 is increased.

Since the width of the gate line is determined by the resistance value required for the semiconductor device, the channel width W required for the TFT 8 is smaller than the required gate line width.
Is shorter, the channel width of the TFT 8 may be reduced by reducing the width of a portion of the gate line that contacts the spatial intersection with the data line.

(Embodiment 3) FIG. 4 is a schematic diagram showing a configuration of a pixel of a semiconductor device according to Embodiment 3 of the present invention. FIG.
As shown in FIG. 7, in the present embodiment, the portion corresponding to the source electrode 21 in the data line is made thicker and the channel length L is made shorter as in the second embodiment.

(Embodiment 4) FIG. 5 is a sectional view of a pixel of an X-ray sensor according to Embodiment 4 of the present invention. In the present embodiment, on the pixel of the semiconductor device shown in any of FIG. 2 to FIG. 4, visible light or the like such that the wavelength of radiation such as X-rays can be detected by the photodiode 7 via the protective layer 23. A phosphor layer 24 which is a wavelength converter for converting light is provided. X-rays and the like incident on the phosphor layer 24 are converted into visible light and the like, incident on the photodiode 7, generate carriers in the semiconductor layer 14, and are read by a reading device (not shown). For the phosphor layer 24, a gadolinium-based phosphor, cesium iodide, or the like is used.

(Embodiment 5) FIG. 6 is a schematic diagram showing a configuration of a pixel of a semiconductor device according to Embodiment 5 of the present invention. FIG.
7 is an equivalent circuit diagram of the pixel in FIG. FIG. 8 is a cross-sectional view of the pixel of FIG. In the present embodiment, an X-ray-to-electron conversion element 27, a capacitor 25 for accumulating charges obtained by conversion by the X-ray-to-electron conversion element 27, and a TFT 8 are provided.
Further, the drain electrode 22 of the TFT 8 and one electrode of the capacitor 25 are connected to each other, and further, an X-ray-electron conversion element 27 is connected thereto via a connection bump 26.

The X-ray-to-electron conversion element 27 is biased by a power supply (not shown).
Electrons are generated by the energy of the line. The electrons are stored in the capacitor 25 and read out as a signal by a reading device (not shown) via the TFT 8. As a material of the X-ray-electron conversion element 27, a material such as amorphous selenium, gallium arsenide, or PbI ₂ is used. As shown in FIG. 8, in the semiconductor device, the X-ray-electron conversion layer 27 is provided commonly to a plurality of pixels.

Embodiment 6 FIG. 15 is a sectional view of a semiconductor device according to Embodiment 6 of the present invention. 16 and 17 are plan views of FIG. As shown in FIG. 15, in the present embodiment, the light shielding layer 30 is provided on the TFT 8 so that the visible light generated in the phosphor layer 24 is not incident on the TFT 8. In addition, the image quality is prevented from deteriorating due to leakage due to a decrease in off-resistance.

Therefore, in the semiconductor device of the present embodiment, good image quality can be obtained without the influence of leakage of the TFT 8 due to light. The light shielding layer 30 may be formed of a metal, or may be formed of an organic or inorganic material. Although the drawing shows a state in which the light shielding layer 30 is formed in the protective layer 23, the light shielding layer 30 may be provided between the protective layer 23 and the phosphor layer 24.

As shown in FIGS. 16 and 17, the light shielding layer 30 may be provided so as to cover the upper part of the TFT 8,
It may be provided so as to cover the entire gate line.

[0033]

As described above, according to the present invention, since the switching element is formed so as to include the spatial intersection between the control signal line and the readout signal line, the aperture ratio of the pixel of the semiconductor device can be increased. In addition, the speed of driving the semiconductor device can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a pixel of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the pixel of FIG. 1;

FIG. 3 is a schematic diagram illustrating a configuration of a pixel of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a configuration of a pixel of a semiconductor device according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a pixel of an X-ray sensor according to Embodiment 4 of the present invention.

FIG. 6 is a schematic diagram illustrating a configuration of a pixel of a semiconductor device according to a fifth embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram of the pixel of FIG. 6;

FIG. 8 is a sectional view of the pixel in FIG. 6;

FIG. 9 is a schematic diagram showing a configuration of a conventional area sensor.

FIG. 10 is a schematic diagram of a pixel of the area sensor of FIG. 9;

11 is a cross-sectional view illustrating a configuration of a pixel in FIG.

FIG. 12 is a plan view illustrating a configuration of a pixel in FIG. 10;

FIG. 13 is a schematic diagram showing a configuration of a conventional liquid crystal display.

14 is a schematic diagram of a pixel of the liquid crystal display of FIG.

FIG. 15 is a schematic diagram illustrating a configuration of a pixel of a semiconductor device according to a sixth embodiment of the present invention.

FIG. 16 is a plan view of FIG.

FIG. 17 is a plan view of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 readout device 2 gate driver 3 power supply 4 liquid crystal source driver 5 liquid crystal gate driver 6 analog multiplexer 7 photodiode 8 TFT 9 D / A converter 10 liquid crystal display capacitance 11 glass substrate 12 lower electrode 13 n layer 14 semiconductor layer 15 p layer 16 Upper electrode 17 Gate electrode 18 Gate insulating film 19 Semiconductor layer 20 Ohmic layer 21 Source electrode 22 Drain electrode 23 Protective layer 24 Phosphor layer 25 Capacitor 26 Connection bump 27 X-ray electron conversion element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 31/10 H01L 31/10 A F term (Reference) 2H092 JA26 JA29 JA30 JA38 JA42 JB23 JB32 JB51 KA05 NA07 4M118 AA01 AB01 BA05 CA05 CB06 CB11 FB03 FB09 FB13 FB16 FB19 FB24 FB27 GA10 GB05 GB07 GB11 5C094 AA10 BA03 BA43 CA19 DA15 EA04 EA07 EB05 FB14 5F049 MA01 MA04 MB01 MB05 MB07 RA08 SE20 UA11 UA20 WA07 NN20 NN20 NN

Claims (10)

[Claims] A pixel having a switching element, a control signal line transmitting a signal for controlling on / off of the switching element, and a read signal line transmitting a signal read when the switching element is turned on. In the semiconductor device provided, the switching element is formed so as to include a spatial intersection between the control signal line and the read signal line. 2. The switching element is a thin film transistor, and has a gate electrode formed to include a portion of the control signal line contacting the intersection, and includes a portion of the read signal line contacting the intersection. 2. The semiconductor device according to claim 1, wherein the source electrode is formed as described above. 3. The semiconductor device according to claim 1, wherein the pixel includes a photoelectric conversion element or a liquid crystal display capacitor. 4. The semiconductor device according to claim 2, wherein a ratio between a channel length and a channel width of the thin film transistor is changed by changing a size of the intersection. 5. The semiconductor device according to claim 1, further comprising a wavelength conversion means for converting radiation into light above the pixel. 6. The semiconductor device according to claim 5, wherein said wavelength converting means is a phosphor for converting X-rays into visible light. 7. The semiconductor device according to claim 3, wherein the photoelectric conversion element is made of amorphous selenium, gallium arsenide, or PbI ₂ . 8. The semiconductor device according to claim 3, wherein the photoelectric conversion element is a PIN photodiode or an MIS sensor using amorphous silicon as a material. 9. The semiconductor device according to claim 1, wherein said switching element is made of amorphous silicon. 10. The semiconductor device according to claim 1, wherein the switching element is shielded from light by a light shielding unit.