JP5201157B2 - Infrared imaging device - Google Patents

Description

  The present invention relates to an infrared imaging device that detects infrared rays by converting them into heat.

  Among infrared imaging devices used in various fields, there is an uncooled infrared imaging device that does not require a cooling device. As a general non-cooling type infrared imaging device, an infrared detection pixel provided with an infrared absorption part and a thermoelectric conversion part on a substrate and provided to be held hollow via a support leg connected to the substrate is provided. There is something used. In this method, incident infrared rays are converted into heat by the infrared absorption unit, and a temperature change due to the heat converted by the thermoelectric conversion unit is converted into an electrical signal, which is output as a detection signal. In addition, in order to improve sensitivity to weak thermal fluctuations in the infrared imaging device, the thermal conductivity of the support legs is reduced so that the heat from the infrared absorption part received by the thermoelectric conversion part does not escape via the support legs. Is one of the important factors. For this reason, the support legs made of a material with low thermal conductivity are made thinner and longer in the design range, and the heat conductance of the support legs is improved by laying out the support legs longer and heat escape from the infrared absorption part received by the thermoelectric conversion part. Suppression is done.

  There is an infrared imaging device including a pixel area that is multi-dimensionally arranged in a two-dimensional manner by using an infrared absorption portion included in the infrared detection pixel as one pixel region. In a conventional multi-pixel infrared imaging device, a drive line for driving a thermoelectric conversion unit in each infrared detection pixel is wired along the row direction between each infrared detection pixel, and a detection signal of each infrared detection pixel is transmitted. After wiring the signal lines along the column direction between the infrared detection pixels, each infrared detection pixel is connected to one of the adjacent drive lines via a support leg, and one of the adjacent signal lines is connected to the support leg. Connected. With such a configuration, the thermoelectric conversion unit in each infrared detection pixel is driven in units of rows, and the detection results are read in time series in the column direction to obtain the imaging results for the entire pixel included in the infrared imaging device. doing.

  In proceeding with the increase in the number of pixels of the infrared imaging element, it is necessary to reduce the unit pixel size in order to reduce the size of the infrared imaging element itself. If the conventional support leg structure is used as it is, the layout length is increased. Sensitivity degradation becomes a problem due to the effect of heat conduction by the shortened support legs. Therefore, in order to realize a large number of pixels and high sensitivity, it is possible to reduce the thermal conductance of the support leg by thinning the support leg, and to suppress the escape of heat from the thermoelectric conversion part (for example, Patent Document 1).

JP 2001-28165 A (page 4, FIG. 2)

  However, in Patent Document 1, it is difficult to further reduce the thickness of the support leg in realizing the further increase in the number of pixels and the sensitivity, and it is difficult with the current manufacturing process technology, and the sensitivity deterioration due to the deterioration of the thermal conductance in the support leg. In order to suppress this, there was a problem that the line length of the support leg had to be secured. On the other hand, if the line length of the support leg is secured while the unit pixel size is reduced, the area of the infrared detection pixel is reduced, so that the area of the infrared detection pixel is sacrificed and the sensitivity is reduced due to the area reduction. There was a problem.

  The present invention has been made in order to solve the above-described problems, and an infrared imaging element capable of suppressing deterioration in sensitivity due to deterioration of thermal conductance in a support leg without sacrificing the area of the infrared detection pixel. Is what you get.

In the infrared imaging device according to the present invention, a pixel area in which infrared detection pixels that are hollowly held on the substrate by the first support leg and the second support leg are two-dimensionally arranged, and a drive signal is input to the infrared detection pixel. A drive line that commonly connects the drive poles for each row via a first support leg that holds the infrared detection pixel, and a signal pole that outputs a detection signal of the infrared detection pixel is a second that holds the infrared detection pixel A signal line commonly connected to each column through a support leg, and the drive line is one of the row directions adjacent to each infrared detection pixel using a multilayer line having two layers separated by an insulating layer. only wired to the drive electrode of each of the infrared detection pixel is obtained by the so that is connected to a drive line close to the second with respect to the infrared detection pixel.
In the infrared imaging device according to the present invention, a pixel area in which infrared detection pixels that are hollowly held on the substrate by the first support leg and the second support leg are two-dimensionally arranged, and a drive signal is sent to the infrared detection pixel. A drive line for commonly connecting the drive electrodes to be input for each row via the first support legs for holding the infrared detection pixels, and a signal pole for outputting the detection signals of the infrared detection pixels are used for holding the infrared detection pixels. A signal line commonly connected to each column through two support legs, and the signal line is arranged in a column direction adjacent to each infrared detection pixel using a multilayer line having two layers separated by an insulating layer. Only one of them is wired, and the signal electrode of each infrared detection pixel is connected to the signal line closest to the infrared detection pixel.

  In the present invention, the drive lines or signal lines connected to the rows and columns of the two-dimensionally arranged infrared detection pixels are separated by an insulating layer instead of wiring the drive lines or signal lines themselves. A part of the wiring region of the drive line or signal line is provided by using a multilayer line having two layers and wiring the two layers so that two drive lines or two signal lines are provided. Can be reduced. Thereby, a part of the reduced wiring area can be used for area expansion of the thermoelectric conversion part and securing of the length of the support leg. Therefore, it is possible to obtain an infrared imaging device capable of suppressing deterioration in sensitivity when dealing with the increase in the number of pixels.

1 is a perspective view of an infrared imaging element showing Embodiment 1 of the present invention. It is a schematic diagram of the infrared detection pixel of Embodiment 1 of this invention. FIG. 3 is a layout diagram of infrared detection pixels and support legs in the infrared imaging element showing Embodiment 1 of the present invention. It is another example of the layout figure of the infrared detection pixel and support leg in the infrared image sensor which shows Embodiment 1 of this invention. It is a layout figure of the infrared detection pixel and support leg in the infrared image sensor which shows Embodiment 2 of this invention. It is a layout figure of the infrared detection pixel and support leg in the infrared image sensor which shows Embodiment 3 of this invention. It is a schematic diagram of the infrared detection pixel in the infrared image sensor which shows Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a schematic configuration of an infrared imaging element according to Embodiment 1 for carrying out the present invention. As shown in FIG. 1, the infrared imaging element has infrared detection pixels 2 arranged on a substrate 1 in two dimensions of M rows × N columns. Here, M and N are natural numbers. The multilayer line 3 provided with the drive lines 3a and 3b is wired between the infrared detection pixel 2 and the infrared detection pixel 2 along the row direction, and each drive line is arranged in a predetermined row. And the drive scanning circuit 5 or 8. The signal line 4 is wired between the infrared detection pixel 2 and the infrared detection pixel 2 along the column direction, and each signal line is connected to the infrared detection pixel 2 and the signal scanning circuit 6 or 9 arranged in a predetermined row, respectively. And connected to. The signal scanning circuit 6 is connected to the output amplifier 7, and the signal scanning circuit 9 is connected to the output amplifier 10. The multilayer line 3 is provided with two wiring layers between the insulating layers 11 indicated by hatching on the substrate 1, and each has a first drive line 3 a and a second drive line 3 b. Further, since the first drive line 3a and the second drive line 3b are divided by the insulating layer 11, they are not electrically connected.

  The first drive line 3a and the second drive line 3b are made of, for example, aluminum, titanium, titanium nitride, tungsten, tungsten silicide, or the like. In particular, in the portion where the first drive line 3a and the second drive line 3b intersect with the signal line 4, conductive silicon and a refractory metal such as tungsten, titanium, cobalt, tantalum, platinum, molybdenum, The wiring may be made so as to be connected by silicide of these refractory metals. In this manner, by using a material having a high melting point instead of a wiring material such as aluminum, an interlayer insulating film formed in a later step can be formed by a thermal CVD (Chemical Vapor Deposition) method having a high formation temperature. it can. Further, it is preferable that the first drive line 3a and the second drive line 3b have the same wiring thickness or the same resistance value.

  FIG. 2 is a schematic diagram showing the periphery of the infrared detection pixel 2 in the section A in the infrared imaging device of FIG. 1 from the horizontal direction. In FIG. 2, 11 is an insulating film, 12 is an infrared absorbing part, 13 is an etching hole, 14 is a cavity, 15a and 15b are support legs, 16 is a thermoelectric conversion part, 17 is an insulating film, 18 is a thin film wiring, and 19 is a signal. Is a line.

  As shown in FIG. 2, a concave cavity 14 is formed in the substrate 1 by etching through an etching hole 13, and the thermoelectric conversion portion 16 is held hollow by support legs 15 a and 15 b in the cavity 14. The infrared detection pixel 2 includes a thermoelectric conversion unit 16 provided on an insulating film 17 (buried oxide film), and an infrared absorption unit 12 provided on the thermoelectric conversion unit 16.

  The infrared absorption section 12 in FIG. 2 has an umbrella structure and is an infrared absorption film such as indium oxide, zinc oxide, tin oxide, ITO (indium tin oxide) conductive oxide thin film, titanium, chromium, nichrome, etc. And a metal compound thin film such as titanium nitride and vanadium nitride and a dielectric film holding the metal compound thin film.

  The thermoelectric conversion unit 16 is configured by a temperature sensitive element whose electrical characteristics change with temperature, such as a pn junction diode or a transistor. For example, when the thermoelectric conversion unit 16 is a pn junction diode, by applying a predetermined voltage as a drive signal to the anode of the pn junction diode, the thermoelectric conversion unit 16 receives the potential signal output from the cathode from the infrared absorption unit 12. It becomes a potential signal according to the heat.

  Moreover, since the insulating film 17 is included in the heat capacity of the thermoelectric conversion unit 16, the thinner one has a smaller heat capacity. Therefore, the insulating film 17 is preferably an SOI (Silicon On Insulator) substrate in which a silicon layer is formed on a silicon substrate via a silicon oxide layer. By using this SOI substrate, a pn junction diode can be formed in the SOI layer, and the thermoelectric converter 16 can be formed. In this case, since the signal readout circuit and the temperature sensitive element can be simultaneously formed by a general-purpose semiconductor process, an infrared imaging element suitable for mass production can be manufactured with a high yield.

  The support legs 15 a and 15 b connect one support leg 15 a to the infrared detection pixel 2 and the multilayer line 3, and connect the other support leg 15 b to the infrared detection pixel 2 and the signal line 4 to thereby detect the infrared detection pixel 2. Hold the hollow. The thin film wiring 18 provided in the support leg 15a connected to the drive line is a wiring for electrically connecting the thermoelectric converter 16 and the drive line, and in the support leg 15b connected to the signal line. The thin film wiring 18 provided in the wiring is a wiring for electrically connecting the thermoelectric converter 16 and the signal line.

  Here, the operation of the infrared imaging device of the present embodiment will be described. The infrared absorption unit 12 provided in each infrared detection pixel 2 converts incident infrared rays into heat and supplies the heat to the thermoelectric conversion unit 16 of the infrared detection pixel 2. At this time, the drive scanning circuit 5 or 8 drives the thermoelectric conversion units 16 of the infrared detection pixels 2 in the corresponding row in units of rows via a drive line connected to the infrared detection pixels 2. The thermoelectric conversion unit 16 of the infrared detection pixel 2 in the row thus driven outputs a detection signal obtained by converting a temperature change caused by the supplied heat into an electric signal to a connected signal line. While this is scanned for each column by the signal scanning circuit 6 or 9, each detection signal output from the thermoelectric conversion unit 16 of the infrared detection pixel 2 in the driven row is captured and supplied to the output amplifier 7 or 10 for output. To do. When the signal scanning circuit 6 or 9 completes the capturing operation in time series, the driving scanning circuit 5 or 8 drives the next row, and the signal scanning circuit 6 or 9 performs a similar capturing operation. In this way, infrared detection signals for M rows × N columns can be obtained. Here, in order to shorten the time required for detecting one screen (for M rows × N columns), this scanning control is divided and provided in parallel by having two sets of drive scanning circuits, signal scanning circuits, and output amplifiers. It is operating.

  Next, an example of the layout of the support legs that connect the infrared detection pixels 2 to the multilayer lines 3 and the signal lines 4 will be described. FIG. 3A is a schematic view of a part of the infrared detection pixels 2 in the (m-2) th to (m + 1) th rows in FIG. 1 as viewed from above. M in this figure is shown as an arbitrary natural number of 3 or more and M-1 or less. Here, the multilayer line 3 is not wired between the infrared detection pixel 2 in the m-th row and the infrared detection pixel 2 in the m + 1-th row, and the infrared detection pixel 2 in the m-1 row and the infrared detection pixel in the m-th row. 2 and between the infrared detection pixel 2 in the (m + 1) th row and the infrared detection pixel 2 in the (m + 2) th row.

  FIG. 3B shows a cross section B of FIG. The cross section B is a connection point between the multilayer line 3 and the support leg 15a that holds the infrared detection pixels 2 in the (m-2) th row, and the first drive line 3a and the support leg 15a provided inside the multilayer line 3 are. It shows that the thin film wiring 18 provided inside is connected. FIG. 3C shows a cross section C of FIG. The section C is a connection point between the multilayer line 3 and the support leg 15a holding the infrared detection pixels 2 in the (m + 1) th row, and the second drive line 3b provided inside the multilayer line 3 and the inside of the support leg 15a. It is shown that the thin film wiring 18 provided in is connected.

  From these connection relationships, the drive line 3a provided inside the multilayer line 3 wired between the m-1 and m rows is connected to the thermoelectric conversion unit 16 in the m-2 row and driven. The line 3b is connected to the thermoelectric conversion unit 16 in the (m + 1) th row. This connection relationship is the same for the other multilayer wires 3. At this time, the inner layer for the drive line 3a provided in the multilayer line 3 adjacent to the infrared detection pixel 2 in the first row and the multilayer line 3 adjacent to the infrared detection pixel 2 in the Mth row are provided. The inner layer for the drive line 3b is not used here. Therefore, what is wired at the end need not have a multilayer structure.

  As described above, the drive line connected to each row of the two-dimensionally arranged infrared detection pixels 2 is not wired with the drive line itself, but has a multilayer line having two layers separated by an insulating layer. 3, wiring is performed so that two drive lines are provided in each of the two layers, so that one wiring region for two drive lines conventionally required for each infrared detection pixel 2 is provided. The wiring area for a minute is sufficient. Thereby, a part of the reduced wiring area can be used for expanding the area of the infrared detection pixel 2 and securing the length of the support legs 15a and 15b. Therefore, it is possible to obtain an infrared imaging device capable of suppressing deterioration in sensitivity when dealing with the increase in the number of pixels.

  In addition, the wiring length of the support legs is laid out longer by connecting the multilayered line to the thermoelectric conversion unit in the adjacent infrared detection pixel 2 instead of the thermoelectric conversion unit in the adjacent infrared detection pixel. Therefore, the thermal conductance of the support leg is improved, and the effect of suppressing the heat escape from the infrared absorption unit received by the thermoelectric conversion unit is increased.

  FIG. 4 shows another example of the routing shape of the support legs 15a and 15b. The routing shape of the support leg 15a of the m-th row infrared detection pixel and the support leg 15a of the m + 1-th row infrared detection pixel is shown. The support legs 15b of the m-th infrared detection pixels and the support legs 15b of the m + 1-th infrared detection pixels are made to have the same shape. As described above, since the routing shapes of the support legs 15a and 15b of the respective infrared detection pixels are made uniform, the inclination of the thermoelectric conversion unit 16 due to internal stress can be suppressed.

Embodiment 2. FIG.
In the first embodiment, the drive line is configured to be a multilayer line, but the signal line may be a multilayer line. FIG. 5A shows a layout diagram of the infrared detection pixels and the support legs in the infrared imaging element according to Embodiment 2 of the present invention. One of the infrared detection pixels 2 in the (n−2) th column to the (n + 1) th column is shown in FIG. It is the schematic diagram which looked at the part from the top. Here, n is an arbitrary natural number of 3 to N-1. Here, the multilayer line 4 is not wired between the infrared detection pixel 2 in the nth column and the infrared detection pixel 2 in the (n + 1) th column, and the infrared detection pixel 2 in the (n−1) th column and the infrared detection pixel in the nth column. 2 and between the infrared detection pixels 2 in the (n + 1) th column and the infrared detection pixels 2 in the (n + 2) th column.

  FIG.5 (b) shows the cross section D of Fig.5 (a). A section D is a connection point between the multilayer line 4 and the support leg 15b that holds the infrared detection pixels 2 in the (n-2) th column, and the first signal line 4a and the support leg 15b provided inside the multilayer line 4 are. It shows that the thin film wiring 18 provided inside is connected. FIG. 5C shows a cross section E of FIG. The section E is a connection point between the multilayer line 4 and the support leg 15b that holds the n + 1-th infrared detection pixels 2, and the second signal line 4b provided inside the multilayer line 4 and the inside of the support leg 15b. It is shown that the thin film wiring 18 provided in is connected.

  As shown in FIG. 5, a first signal line 4a provided inside a multilayer line 4 wired between the infrared detection pixel 2 in the (n-1) th column and the infrared detection pixel 2 in the nth column, and n The thin film wiring 18 provided in the support leg 15b holding the infrared detection pixels 2 in the -2nd column is connected, and is connected to the thermoelectric conversion unit 16 in the (n-2) th column via this. On the other hand, the second signal line 4b provided in the multilayer line 4 wired between the infrared detection pixel 2 in the (n-1) th column and the infrared detection pixel 2 in the nth column, and the infrared detection in the (n + 1) th column. The thin film wiring 18 provided in the support leg 15b holding the pixel 2 is connected to the thermoelectric conversion unit 16 in the (n + 1) th column via the thin film wiring 18.

  From these connection relations, the signal line 4a provided inside the multilayer line 4 wired between the (n-1) th column and the nth column is connected to the thermoelectric conversion unit 16 in the infrared detection pixel 2 in the (n-2) th column. The signal line 4b is connected to the thermoelectric conversion unit 16 in the infrared detection pixel 2 in the (n + 1) th column. This connection relationship is the same for the other multilayer wires 4. At this time, the inner layer for the signal line 4a provided in the multilayer line 4 adjacent to the infrared detection pixel 2 in the first column and the multilayer line 4 adjacent to the infrared detection pixel 2 in the Nth column are provided. The inner layer for the signal line 4b is not used here. Therefore, what is wired at the end need not have a multilayer structure.

  As described above, the signal line connected to each column of the two-dimensionally arranged infrared detection pixels 2 is not wired with the signal line itself, but is a multilayer line having two layers separated by an insulating layer. 4 is provided so that two signal lines are provided in each of the two layers, thereby providing one wiring area for two signal lines that are conventionally required for each infrared detection pixel 2. The wiring area for a minute is sufficient. Thereby, a part of the reduced wiring area can be used for expanding the area of the infrared detection pixel 2 and securing the length of the support legs 15a and 15b. Therefore, it goes without saying that the intended purpose can be achieved as in the first embodiment.

Embodiment 3 FIG.
In the first embodiment, the drive line is configured as a multilayer line, and in the second embodiment, the signal line is configured as a multilayer line. However, both the drive line and the signal line are configured as multilayer lines, thereby reducing the wiring area. This can be used to enlarge the pixel area of the detection pixel 2 and to secure the length of the support legs 15a and 15b. FIG. 6A shows a third embodiment of the present invention, and is a schematic view of a part of infrared detection pixels 2 from m−1 rows and n−1 columns to m + 2 rows and n + 2 columns as viewed from above. In this figure, n is an arbitrary natural number of 2 or more and N-2 or less, and m is an arbitrary natural number of 2 or more and M-2 or less. FIG. 6B shows a cross section F. Here, between the infrared detection pixel 2 in the m-th row and the infrared detection pixel 2 in the (m + 1) -th row, and between the infrared detection pixel 2 in the n-th column and the infrared detection pixel 2 in the (n + 1) -th row, the multilayer line 3 and 40 is not wired, and between the m-1 row infrared detection pixel 2 and the mth row infrared detection pixel 2 and between the m + 1 row infrared detection pixel 2 and the m + 2 row infrared detection pixel 2. A multilayer line 3 is formed between the infrared detection pixel 2 in the (n-1) th column and the infrared detection pixel 2 in the nth column and between the infrared detection pixel 2 in the (n + 1) th column and the infrared detection pixel 2 in the (n + 2) th column. Line 4 is wired.

  In this case, the thermoelectric conversion unit 16 provided in the m-th row and n-th column infrared detection pixel 2 is a multilayer line wired between the n-1th column infrared detection pixel 2 and the n-th column infrared detection pixel 2. 4 is connected via a support leg 15b, and the thermoelectric converter 16 provided in the infrared detection pixel 2 in the (n + 1) th column includes the infrared detection pixel 2 in the (n + 1) th column and the infrared detection in the (n + 2) th column. A signal line 4a provided on the multilayer line 4 wired between the pixel 2 and the pixel 2 is connected via a support leg 15b.

  As described above, the drive lines and the signal lines themselves are not wired to the drive lines and the signal lines connected to each column of the two-dimensionally arranged infrared detection pixels 2 but separated by the insulating layer. By using multilayer lines 3 and 4 having two layers and wiring the two layers so that two drive lines are provided or two signal lines are provided, each of the conventional infrared detection pixels 2 is provided. A total of two wiring areas can be reduced in the required drive lines and signal lines. Thereby, a part of the reduced wiring area can be used for expanding the area of the infrared detection pixel 2 and securing the length of the support legs 15a and 15b. Therefore, since the wiring area required for the pixels can be further reduced, it is possible to obtain an infrared imaging device that can further improve the sensitivity.

Embodiment 4 FIG.
FIG. 7 (a) shows an infrared detection pixel in the infrared imaging element showing Embodiment 4 of the present invention. In FIG. 7A, 11 is an insulating film, 12 is an infrared absorbing part, 13 is an etching hole, 14 is a cavity, 15a and 15b are support legs, 16 is a thermoelectric conversion part, 17 is an insulating film, 18 is a thin film wiring, Reference numeral 19 denotes a signal line. Here, FIG. 7A is also a schematic diagram showing a cross section A portion of the infrared imaging device of FIG. 1 from the horizontal direction. As shown in FIG. 7A, the support legs 15a and 15b are connected on the thermoelectric converter 16 so that the infrared detection pixel 2 is held hollow. With such a configuration, it depends on the layout area of the support legs 15a and 15b as shown in the layout diagram of the infrared detection pixels 2 and the support legs 15a and 15b in the m-th and m + 1-th lines in FIG. 7B. Thus, it is not necessary to reduce the area of the thermoelectric conversion unit 16.

  In addition, when the thermoelectric conversion unit 16 is composed of a pn diode, there are a component determined by physical properties such as shot noise and a component that varies depending on the structure and process method such as 1 / f noise. The performance of the noise to noise ratio is affected. This 1 / f noise has a correlation with the volume of the portion where there is a carrier trap level, generally, the entire volume of the thermoelectric conversion unit 16, and the 1 / f noise is reduced when the thermoelectric conversion unit 16 has a volume as large as possible. It is possible to achieve a noise reduction effect.

  As described above, the support legs 15a and 15b are connected on the thermoelectric conversion unit 16 as shown in FIG. 7A so as to hold the infrared detection pixel 2 in a hollow state. Since the entire volume of the thermoelectric conversion unit 16 can be ensured while ensuring the length, the suppression force against the heat escape from the infrared absorption unit received by the thermoelectric conversion unit is larger than the infrared detection pixel shown in the first embodiment. In addition, the noise can be further reduced.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Infrared detection pixel 3 Multi-layer line 4 Signal line 11 Insulating layer 3a Drive line 3b Drive line

Claims (2)

A pixel area in which infrared detection pixels that are held hollow in the substrate by the first support leg and the second support leg are two-dimensionally arranged;
A drive line for commonly connecting a drive pole for inputting a drive signal to the infrared detection pixel for each row via a first support leg for holding the infrared detection pixel;
A signal line that outputs a detection signal of the infrared detection pixel, and a signal line that is commonly connected to each column via a second support leg that holds the infrared detection pixel;
The drive line is wired only in one of the row directions adjacent to each of the infrared detection pixels using a multilayer line having two layers separated by an insulating layer ,
The infrared imaging element , wherein the drive pole of each infrared detection pixel is connected to the drive line that is second closest to the infrared detection pixel . A pixel area in which infrared detection pixels that are held hollow in the substrate by the first support leg and the second support leg are two-dimensionally arranged;
A drive line for commonly connecting a drive pole for inputting a drive signal to the infrared detection pixel for each row via a first support leg for holding the infrared detection pixel;
A signal line that outputs a detection signal of the infrared detection pixel, and a signal line that is commonly connected to each column via a second support leg that holds the infrared detection pixel;
The signal line is wired only in one of the column directions adjacent to each infrared detection pixel using a multilayer line having two layers separated by an insulating layer ,
The infrared imaging element , wherein the signal electrode of each infrared detection pixel is connected to the signal line that is second closest to the infrared detection pixel .

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