JP5443800B2 - Infrared solid-state image sensor - Google Patents

Description

  The present invention relates to an infrared solid-state imaging device.

  Since infrared rays have a feature of being more permeable to smoke and fog than visible light, infrared imaging is possible regardless of day or night. In addition, since infrared imaging can also obtain temperature information of a subject, it has a wide range of applications such as surveillance cameras and fire detection cameras in the defense field.

  In recent years, the development of “uncooled infrared solid-state imaging devices” that do not require a cooling mechanism has become active. An uncooled type or thermal type infrared solid-state imaging device converts an incident infrared ray having a wavelength of about 10 μm into heat by an infrared absorption film, and some thermoelectric conversion element generates a temperature change of a heat-sensitive part caused by the weak heat thus converted. Is converted into an electric signal. The uncooled infrared solid-state image sensor obtains infrared image information by reading out the electrical signal.

  For example, an infrared solid-state imaging device using a silicon pn junction that converts a temperature change into a voltage change by applying a constant forward current is known (for example, see Patent Document 1). This infrared solid-state imaging device has a feature that it can be mass-produced using a silicon LSI manufacturing process by using an SOI (Silicon on Insulator) substrate as a semiconductor substrate. In addition, since the row selection function is realized by utilizing the rectification characteristics of the silicon pn junction which is a thermoelectric conversion hand element, there is also a feature that the pixel structure can be configured extremely simply.

One index representing the performance of the infrared solid-state image sensor is NETD (Noise Equivalent Temperature Difference) expressing the temperature resolution of the infrared solid-state image sensor. It is important to reduce NETD, that is, to reduce the detected temperature difference corresponding to noise. For this purpose, it is necessary to increase the sensitivity of the signal and reduce the noise.
JP 2002-300475 A

  Patent Document 1 describes threshold voltage clamping processing for reducing the influence of threshold variation of amplification transistors. In this threshold voltage clamping process, when the sampling transistor is turned on, negative charges are accumulated in the gate of the amplification transistor capacitively coupled to the signal line. At this time, the voltage of the coupling capacitance between the signal line and the amplification transistor is preferably converged to (Vdd−Vref) −Vth. Here, Vdd is a bias voltage applied to the pixel by the row selection circuit, Vref is a voltage applied to the signal line from the constant current source, and Vth is a threshold voltage of the pixel. This threshold voltage clamping process can compensate for variations in the threshold voltage of the amplification transistors in each column at the time of signal readout. However, the noise component present in the signal line is held at the moment the threshold voltage is clamped. Therefore, since the information is always referred to at the time of selecting a row, there is a problem that vertical streak noise appears.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an infrared imaging device capable of reducing noise during signal readout as much as possible.

An infrared imaging device according to a first aspect of the present invention is an imaging region in which a semiconductor substrate and a plurality of infrared detection pixels for detecting incident infrared rays are arranged in a matrix on the semiconductor substrate, and each infrared detection pixel Includes an infrared absorption film that absorbs the incident infrared light and converts it into heat, and a thermoelectric conversion unit that includes a first thermoelectric conversion element that converts heat converted by the infrared absorption film into an electrical signal. And an infrared ray in the corresponding row connected to one end of the first thermoelectric conversion element of the infrared detection pixel in the corresponding row. A plurality of row selection lines for selecting detection pixels, and the first thermoelectric conversion elements of the infrared detection pixels in the corresponding columns, which are provided in the imaging region so as to correspond to the columns of the infrared detection pixels. A plurality of signal lines for reading the electric signal from the infrared detection pixel of the column is connected to the other end the corresponding and of the node to be held at the first potential of the constant is connected to a constant power supply, to each signal line A plurality of amplifiers provided correspondingly, each amplifier amplifying a difference between an electric signal read from a corresponding signal line and the potential of the node, and corresponding to each signal line A plurality of reference pixels each having a second thermoelectric conversion element, one end of the second thermoelectric conversion element of each reference pixel being connected to a corresponding signal line, and the other end being a constant second potential. A plurality of recesses arranged in a matrix corresponding to the plurality of infrared detection pixels on the surface portion of the semiconductor substrate, and the infrared detection pixels Each of the thermoelectric converters The first and second support structures are further supported above the corresponding recesses, and one end of the first support structure is connected to one end of the thermoelectric conversion element of the corresponding infrared detection pixel, and the other end corresponds. The first support wiring is connected to a row selection line to which the infrared detection pixel is connected, and the second support structure is connected to the other end of the thermoelectric conversion element of the corresponding infrared detection pixel and to the other end. And a second connection wiring connected to a signal line to which the infrared detection pixel to be connected is connected.

An infrared imaging device according to the second aspect of the present invention is a semiconductor substrate and an infrared detection pixel formed on the semiconductor substrate for detecting incident infrared rays, wherein the infrared detection pixels absorb the incident infrared rays. An infrared detection pixel having a thermoelectric conversion unit, and an infrared detection pixel having a first thermoelectric conversion element that converts the heat converted by the infrared absorption film into an electric signal; A signal line to which one end of the conversion element is connected to read out an electric signal from the infrared detection pixel, a node connected to a constant power source and held at a constant first potential, and an electric signal read out from the signal line And a second thermoelectric conversion element, one end of the second thermoelectric conversion element is connected to the signal line, and the other end is held at a constant second potential. Being said A reference pixel connected in series with one thermoelectric conversion element, and a recess is formed in the surface portion of the semiconductor substrate corresponding to the infrared detection pixel, and the infrared detection pixel includes the thermoelectric conversion unit. The first and second support structures are further supported above the recess, and one end of the first support structure is connected to one end of the thermoelectric conversion element of the infrared detection pixel, and the other end has a constant potential. The first connection wiring connected to the power supply to be supplied and the second support structure part are connected to the other end of the thermoelectric conversion element of the corresponding infrared detection pixel and the other end is connected to the signal line. Connection wiring.

  According to the present invention, it is possible to reduce noise at the time of signal reading as much as possible.

1 is a circuit diagram showing a configuration of an infrared imaging device according to a first embodiment of the present invention. The top view of the sensitive pixel used for 1st Embodiment. Sectional drawing of the sensitive pixel used for 1st Embodiment. FIG. 3 is a plan view of a specific example of an insensitive pixel used in the first embodiment. FIG. 4 is a cross-sectional view of a specific example of an insensitive pixel used in the first embodiment. Sectional drawing of the other specific example of the insensitive pixel used for 1st Embodiment. A circuit diagram showing composition of an infrared image sensor by a 2nd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
The configuration of the infrared imaging device according to the first embodiment of the present invention is shown in FIG. The infrared imaging device 1 of the present embodiment is formed on a semiconductor substrate (not shown), and includes an imaging region 10 including pixels arranged in a matrix, a readout circuit 30, a row selection circuit 40, and a column selection circuit 42. And.

The imaging region 10 includes six pixels 11 ₁ , 11 ₂ , 12 ₁₁ , 12 ₁₂ , 12 ₂₁ , and 12 ₂₂ arranged in 3 rows and 2 columns. In general, the imaging region usually includes more pixels, but in the present embodiment, it is assumed to be 6 pixels for convenience. The pixels 11 ₁ , 11 ₂ arranged in the first row are insensitive pixels (also referred to as reference pixels) that do not have sensitivity to infrared rays, and the pixels 12 ₁₁ , 12 ₁₂ , arranged in the second row and the third row, Reference numerals 12 ₂₁ and 12 ₂₂ denote sensitive pixels (also referred to as infrared detection pixels) capable of detecting infrared rays. The insensitive pixels 11 ₁ and 11 ₂ may be either thermal insensitive pixels or optical insensitive pixels. The structure of the thermal insensitive pixel or the optical insensitive pixel will be described later. Each pixel 11 ₁ , 11 ₂ , 12 ₁₁ , 12 ₁₂ , 12 ₂₁ , 12 ₂₂ includes at least one thermoelectric conversion element, for example, a diode 14 formed of a pn junction.

The anode of each diode 14 in the second row of sensitive pixel ₁₂ 11, _{12 12} are connected to the row select line 16 _1, the anode of each diode 14 of the third row of sensitive pixel ₁₂ 21, _{12 22} It is connected to the row select line 16 _2. Each of the row selection lines 16 ₁ and 16 ₂ is sequentially selected by the row selection circuit 40, and a bias voltage Vd is applied to the selected row selection line.

The cathodes of the diodes 14 of the first row of sensitive pixels 12 ₁₁ and 12 ₂₁ are connected to the first column of vertical signal lines (hereinafter also simply referred to as signal lines) 18 ₁ , and the second row of sensitive pixels. 12 _{12, 12 22} of the cathode of each diode 14 is connected to the vertical signal line 18 ₂ of the second column.

The readout circuit 30 includes operational amplifiers 31 ₁ and 31 ₂ , feedback resistors 32 ₁ and 32 ₂ , and column selection transistors 34 ₁ and 34 ₂ .

One end of the signal line 18 ₁ in the first column is connected to the anode of the insensitive pixel 11 _first diode 14 of the first column, the cathode of the insensitive pixels 11 _first diode 14 of the first row at a constant potential Vs Retained. One end of the signal line 18 ₂ of the second column is connected to an anode of a non-sensitivity pixel 11 _{and second} diode 14 of the second column, the cathode constant potential of the second row of non-sensitivity pixel 11 _{and second} diode 14 Held at Vs. The other end of the signal line 18 ₁ in the first column are connected to the negative input terminal of the operational amplifier 31 _1, the other end of the signal line 18 ₂ in the second column are connected to the negative input terminal of the operational amplifier 31 _2. The positive input terminals of the operational amplifiers 31 ₁ and 31 ₂ are connected to a common node 33. Feedback resistor 32 ₁ is provided between the negative input terminal of the operational amplifier 31 ₁ and the output terminal, a feedback resistor 32 ₂ is provided between the output terminal and the negative input terminal of the operational amplifier 31 _2. The output terminal of the operational amplifier 32 ₁ is connected to the horizontal signal line 38 through column selection transistors 34 _1, the output terminal of the operational amplifier 32 ₂ is connected to the horizontal signal line 38 through the column selection transistor 34 _2. The gates of the column selection transistors 34 ₁ and 34 ₂ are connected by a column selection circuit 42, and the column selection transistors 34 ₁ and 34 ₂ are turned on by being selected by the column selection circuit 42.

Row select line row selection circuit 40 selects, for example, by applying a bias voltage Vd to the row select line 16 _1, and the diode 14 of the sensitive pixel ₁₂ 11, _{12 12} of the row select line 16 ₁ is selected, the insensitive The series voltage Vd−Vs is applied to each series circuit composed of the diodes 14 of the pixels 11 ₁ and 11 ₂ . For example, if Vd = 0.7V and Vs = −0.7V, a voltage of 0.7V is applied to each of the series circuits.

On the other hand, the diode 14 of the sensitive pixels ₁₂ 21, _{12 22} which is connected to the row select line 16 ₂ unselected, since all are reverse biased, and the row select line 16 ₂ unselected, signal lines 18 ₁ , it is separated from the _182. That is, the diode 14 may have a pixel selection function.

When each of the sensitive pixels 12 ₁₁ , 12 ₁₂ , 12 ₂₁ , and 12 ₂₂ receives infrared rays, the pixel temperature increases. Thereby, the potential Vsl of the signal lines 18 ₁ and 18 ₂ is increased. For example, when the subject temperature changes by 1 K (Kelvin), the temperature of the sensitive pixel changes by about 5 mK. The current value of the diode 14 increases from approximately 1 μA to 20% with respect to a temperature increase of 1 ° C. under the condition of applying Vd = 0.7V. For this reason, when the temperature of the sensitive pixel changes by 5 mK, the current increases by 0.1% (1 nA).

In the infrared imaging device of this embodiment shown in FIG. 1, when a diode (thermoelectric conversion element) of a sensitive pixel and a diode (thermoelectric conversion element) of an insensitive pixel are connected in series and the node 33 is grounded, the sensitive pixel Only the increase in current is amplified by the operational amplifiers 31 ₁ and 31 ₂ . For example, if the resistance values of the feedback resistors 32 ₁ and 32 ₂ are 1 MΩ, the output voltage is 1 nA × 1 MΩ = 1 mV. That is, a change in the subject temperature 1K is output as a response of 1 mV, which is a sufficient value for a thermal infrared imaging device.

The outputs of the operational amplifiers 31 ₁ and 31 _{2 in} each column are sequentially read out by the column selection transistors 34 ₁ and 34 ₂ . The gate voltages of the column selection transistors 34 ₁ and 34 ₂ are sequentially supplied from the horizontal selection circuit 42, and the output voltages of the operational amplifiers 31 ₁ and 31 ₂ are sequentially output through the horizontal signal line 38.

As described above, the row selection line is alternately selected by the row selection circuit 40, and the temperature change of the subject is extracted as an electrical signal by the sensitive pixel connected to the selected row selection line. Are amplified by the operational amplifier, and the amplified electric signals are sequentially read out to the horizontal signal line 38 by the column selection transistors 34 ₁ and 34 ₂ .

  As described in the section of the problem to be solved, in the conventional threshold voltage clamping process, the noise component existing in the signal line is held at the moment when the threshold voltage clamping is performed, and thereafter, when the row selection line is selected. There is a problem that vertical stripe noise appears because the information is always referred to.

  On the other hand, in the infrared imaging device of this embodiment, the difference signal from the insensitive pixel is always compared and output for all the sensitive pixels, so that in principle, noise is not held, and vertical streak noise is generated. Does not occur.

  Next, the structure of the sensitive pixel of the infrared imaging device according to the present embodiment will be described with reference to FIGS. 2 is a plan view of the sensitive pixel 12 of the infrared imaging device according to the present embodiment, and FIG. 3 is a cross-sectional view taken along the cutting line AA shown in FIG. The sensitive pixel 12 is formed on an SOI substrate. This SOI substrate includes a support substrate 101, a buried insulating layer (BOX layer) 102, and an SOI (Silicon-On-Insulator) layer made of silicon single crystal, and a recess 110 is formed on the surface portion. . The sensitive pixel 12 includes a thermoelectric conversion unit 13 formed in the SOI layer and support structure units 130 a and 130 b that support the thermoelectric conversion unit 13 above the recess 110. The thermoelectric conversion unit 13 is formed so as to cover a plurality of (two in FIG. 2 and FIG. 3) diodes 14 connected in series, a wiring 120 connecting these diodes 14, and these diodes 14 and wirings 120. Infrared absorbing film 124 is provided. The support structure portion 130a includes a connection wiring 132a connected to one end of a series circuit composed of a diode having one end connected to a corresponding row selection line and the other end connected in series, and an insulating film 134a covering the connection wiring 132a. It has. The other support structure 130b includes a connection wiring 132b connected to the other end of a series circuit composed of a diode having one end connected to a corresponding vertical signal line and the other end connected in series, and an insulation covering the connection wiring 132b. And a film 134b.

  The infrared absorbing film 124 generates heat due to incident infrared rays. The diode 14 converts heat generated in the infrared absorption film 124 into an electrical signal. The support structure portions 130 a and 130 b are formed to be elongated so as to surround the periphery of the thermoelectric conversion portion 13. Thereby, the thermoelectric conversion part 13 is supported on an SOI substrate in the state substantially insulated from the SOI substrate.

  By having such a structure, the sensitive pixel 12 can store heat generated according to incident infrared rays and output a voltage based on the heat to the signal line.

  The bias voltage Vd from the row selection line is transmitted to the diode 14 through the wiring 132a. The signal that has passed through the diode 14 is transmitted to the vertical signal line through the wiring 132b.

  Next, the configuration of a specific example of the insensitive pixel of the infrared imaging device according to the present embodiment will be described with reference to FIGS. FIG. 4 is a plan view of the insensitive pixel 11 of this specific example, and FIG. 5 is a cross-sectional view taken along the cutting line BB shown in FIG. The insensitive pixel 11 is formed on the SOI substrate in the same manner as the sensitive pixel 12. However, unlike the sensitive pixel 12, the recess 110 is not formed in the region of the SOI substrate where the insensitive pixel 11 is formed. The insensitive pixel 11 includes a plurality of (two in FIG. 2 and FIG. 3) diodes 14 formed in the SOI layer of the SOI substrate and connected in series, a wiring 120 connecting these diodes 14, and one end thereof. A connection wiring 142a connected to one end of a series circuit composed of a diode connected to a power source line of a constant potential Vs and connected in series to the other end, and one end connected to a corresponding vertical signal line and the other end connected in series. A connection wiring 142b connected to the other end of the series circuit formed of the diodes, and an insulating film 125 formed so as to cover the diode 14, the wiring 120, and the connection wirings 142a and 142b.

  In the insensitive pixel (also referred to as thermal insensitive pixel) 11 configured as described above, the heat generated by the diode 14 is transferred to the surrounding insulating film 125, the buried insulating layer 102, and the bulk substrate (not shown). Spread. That is, the thermal conductance between the diode 14 and the surrounding structure is higher than that of the sensitive pixel 12. The insensitive pixel 11 of this specific example does not have the concave portion 110 and therefore does not have a heat storage function. Therefore, the insensitive pixel 11 of this specific example reflects the temperature of the SOI substrate. Such insensitive pixels are also called substrate temperature measurement pixels.

  Next, the configuration of another specific example of the insensitive pixel of the infrared imaging device according to the present embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view of the insensitive pixel 11A of this specific example. The insensitive pixel 11 </ b> A of this specific example is formed on an SOI substrate in which the concave portion 110 is formed on the surface portion, similarly to the sensitive pixel 12. The insensitive pixel 11 </ b> A includes a reflective portion 13 </ b> A formed in the SOI layer, and support structure portions 140 a and 140 b that support the reflective portion 13 </ b> A above the recess 110. The reflecting portion 13A includes a plurality of (two in FIG. 6) diodes 14 connected in series, a wiring 120 connecting these diodes 14, and an infrared reflection formed so as to cover these diodes 14 and the wiring 120. A film 150 and an infrared absorption film 124 formed so as to cover the diode 14, the wiring 120, and the infrared reflection film 150 are provided. The support structure 140a includes a connection wiring 142a connected to one end of a series circuit composed of a diode having one end connected to a power supply line having a constant potential Vs and the other end connected in series, and an insulating film covering the connection wiring 142a 144a. The other support structure 140b includes a connection wiring 142b connected to the other end of a series circuit composed of a diode having one end connected to a corresponding vertical signal line and the other end connected in series, and an insulation covering the connection wiring 142b. And a film 144b.

  The insensitive pixel 11A having such a configuration is also called an optical insensitive pixel, and is different from the sensitive pixel 12 in that the infrared reflecting film 150 is included in the infrared absorbing film 124. This optical insensitive pixel 11A is insensitive to infrared rays because it reflects infrared rays. In other respects, the structure is the same as that of the sensitive pixel 12, and therefore, the reference pixel is more suitable than the substrate temperature measurement pixel (thermal insensitive pixel) 11. For example, the Joule heat component generated when the diode 14 is energized does not exist in the thermal insensitive pixel 11 and is different from the sensitive pixel 12 in this respect, but in the optical insensitive pixel 11A, It has the same temperature component except the temperature change by infrared rays. The infrared reflection film 124 may be formed in the same layer as the wiring layer that forms the operational amplifiers 201 and 202. In this case, the manufacturing process can be shortened and the cost can be reduced.

(Second Embodiment)
Next, an infrared imaging device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a circuit diagram showing a configuration of the infrared imaging element of the present embodiment. The infrared imaging device of the present embodiment has a configuration in which one insensitive pixel and one sensitive pixel are provided in the infrared imaging device of the first embodiment shown in FIG. That is, the cathode is the insensitive pixels 11 ₁ with a diode 14 having an anode connected to a power source of constant potential Vs is connected to the vertical signal lines 18 _1, the other end one end connected to the vertical signal lines 18 ₁ node 38 a sensitive pixel 12 ₁ having a diode 14 connected to the positive side input terminal connected to node 33, an operational amplifier 31 ₁ negative input terminal is connected to the vertical signal lines 18 _1, the output terminal of the operational amplifier 311 and a, a feedback resistor 32 ₁ provided between the negative input terminal and.

In this embodiment, like the first embodiment, the sensitive pixel 12 ₁ and the insensitive pixels 11 ₁ wired in series, and Vd the voltage of the node 38. Intermediate voltage Vsl of the node between the sensitive pixel 12 ₁ and the insensitive pixels 11 ₁ is a virtual ground by grounding node 33 connected to the positive input terminal of the operational amplifier 31 _1. In this case, as in the first embodiment, only current increase caused by infrared detection is amplified by the operational amplifier 31 _1. That is, this embodiment is a single-pixel infrared detector that can always output only an infrared signal without being affected by the temperature of the sensor itself.

  Similar to the first embodiment, the present embodiment does not hold noise in principle and does not generate vertical stripe noise.

  As described above, according to each embodiment of the present invention, it is possible to reduce the noise that is generated in principle when outputting the difference between the insensitive pixel and the sensitive pixel, thereby increasing the S / N ratio. Can be achieved.

  In each of the above embodiments, the pixel is a thermoelectric conversion element that converts heat into an electric signal, and a diode is used. However, a resistor may be used.

1 Infrared imaging device 11 Insensitive pixel (thermal insensitive pixel)
11A Insensitive pixel (optical insensitive pixel)
11 ₁ , 11 ₂ Insensitive pixel 12 Sensitive pixel 12 ₁₁ , 12 ₁₂ , 12 ₂₁ , 12 ₂₂ Sensitive pixel 13 Thermoelectric converter 13A Reflector 14 Diode 16 ₁ , 16 ₂ row selection line 18 ₁ , 18 ₂ Vertical signal Line (signal line)
30 readout circuit 31 ₁ , 31 ₂ operational amplifier 32 ₁ , 32 ₂ feedback resistor 33 node 34 ₁ , 34 ₂ column selection transistor 38 node 40 row selection circuit 42 column selection circuit 101 support substrate 102 buried insulating layer 110 recess 120 wiring 124 infrared absorption Films 130a and 130b Support structure parts 132a and 132b Connection wirings 134a and 134b Insulation films 140a and 140b Support structure parts 142a and 142b Connection wirings 144a and 144b Insulation film 150 Infrared reflection film

Claims (6)

A semiconductor substrate;
An imaging region in which a plurality of infrared detection pixels for detecting incident infrared rays are arranged in a matrix on the semiconductor substrate, each infrared detection pixel absorbing the incident infrared rays and converting it into heat, and An imaging region including a thermoelectric conversion unit having a first thermoelectric conversion element that converts heat converted by the infrared absorption film into an electrical signal;
In the imaging region, the infrared detection pixels in the corresponding row are provided corresponding to the respective rows of the infrared detection pixels, and connected to one end of the first thermoelectric conversion element of the infrared detection pixels in the corresponding row. Multiple row selection lines to select,
In the imaging region, the infrared detection pixels of the corresponding column are provided corresponding to the columns of the infrared detection pixels and connected to the other ends of the first thermoelectric conversion elements of the infrared detection pixels of the corresponding column. A plurality of signal lines for reading out electrical signals from the pixels;
A node connected to a constant power source and held at a constant first potential;
A plurality of amplifiers provided corresponding to each signal line, each amplifier amplifying a difference between an electrical signal read from the corresponding signal line and the potential of the node; and
A plurality of reference pixels provided corresponding to each signal line, each having a second thermoelectric conversion element, one end of the second thermoelectric conversion element of each reference pixel being connected to the corresponding signal line, and the other end being A plurality of reference pixels held at a constant second potential;
With
A plurality of recesses arranged in a matrix corresponding to the plurality of infrared detection pixels are formed on the surface portion of the semiconductor substrate, and each of the infrared detection pixels corresponds to the thermoelectric conversion unit. The first and second support structures are further supported above the recess, and the first support structure is connected to one end of the thermoelectric conversion element of the corresponding infrared detection pixel, and the other end corresponds to the infrared detection. The first support wiring connected to the row selection line to which the pixel is connected, the second support structure is connected to the other end of the thermoelectric conversion element of the corresponding infrared detection pixel and the other end corresponds to the infrared An infrared imaging element having a second connection wiring connected to a signal line to which a detection pixel is connected. A semiconductor substrate;
An infrared detection pixel that is formed on the semiconductor substrate and detects incident infrared rays, wherein the infrared detection pixel absorbs the incident infrared rays and converts the infrared rays into heat, and heat converted by the infrared absorption film. An infrared detection pixel including a thermoelectric conversion unit having a first thermoelectric conversion element that converts the first thermoelectric conversion element into an electrical signal;
One end of the first thermoelectric conversion element is connected, and a signal line for reading an electrical signal from the infrared detection pixel;
A node connected to a constant power source and held at a constant first potential;
An amplifier that amplifies the difference between the electrical signal read from the signal line and the potential of the node;
A reference having a second thermoelectric conversion element, wherein one end of the second thermoelectric conversion element is connected to the signal line, and the other end is held at a constant second potential and connected in series with the first thermoelectric conversion element Pixels,
With
A concave portion is formed on the surface portion of the semiconductor substrate corresponding to the infrared detection pixel, and the infrared detection pixel further includes first and second support structures that support the thermoelectric conversion unit above the concave portion. A first connection wiring having one end connected to one end of the thermoelectric conversion element of the infrared detection pixel and the other end connected to a power source that supplies a constant potential; and the second support structure The structure section includes an infrared imaging element having one end connected to the other end of the thermoelectric conversion element of the corresponding infrared detection pixel and the other end connected to the signal line.   The infrared imaging element according to claim 1, wherein the reference pixel is a thermally insensitive pixel that does not have sensitivity to heat of the incident infrared ray.   3. The optically insensitive pixel according to claim 1, wherein the reference pixel is an optically insensitive pixel that is formed so as to cover the first thermoelectric conversion element and has an infrared reflection film that reflects the incident infrared ray. 4. Infrared imaging device.   The infrared imaging element according to claim 1, wherein the first and second thermoelectric conversion elements are diodes connected in series.   5. The infrared imaging element according to claim 1, wherein the first and second thermoelectric conversion elements are resistors connected in series. 6.

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