JP2001223349A - Infrared solid-state imaging device and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a thermal infrared solid-state imaging device having a small thermal infrared constant detector having a small thermal time constant and high sensitivity. An infrared solid-state imaging device that detects infrared light incident on the infrared detection unit using an infrared detection unit having a pn junction is supported on a semiconductor substrate and a recess provided in the semiconductor substrate. An infrared detector supported by legs, a pn junction element provided in the infrared detector, and a wiring layer connected to both ends of the pn junction element to extract an electric signal from the pn junction element, The pn junction element is
It has a thyristor structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal infrared solid-state imaging device, and more particularly to a thermal infrared solid-state imaging device using a thyristor as an infrared detector.

[0002]

2. Description of the Related Art FIG.
320 x 240 uncooled IRFPA using conventional silico
FIG. 12A is a perspective view of a thermal infrared solid-state imaging device having a conventional structure described in n IC process "Proc. SPIE 3698, p.556 (1999). FIG. FIG. 2 is an enlarged view of a thermal infrared detector 103 included in the device.
FIG. 12B is a sectional view taken along the line 12A-12A in FIG.
It is sectional drawing of a direction. In FIG. 12A, the protective film 108 covering the entire surface is omitted.

[0003] In a thermal infrared solid-state imaging device 200 shown in FIG. 11, a detector array 202 in which thermal infrared detectors 103 are arranged on a single crystal silicon substrate 100 in 3 rows × 3 columns,
A signal processing circuit unit 201 that processes an electric signal output from the thermal infrared detector 103 and outputs the processed signal to the outside is formed. The detector array 202 and the signal processing circuit unit 201 are covered with a protective film 108 made of silicon oxide or the like.

As shown in FIGS. 12A and 12B, in a thermal infrared detector 103, an oxide film 101 is formed on a single crystal silicon substrate 100. Infrared detector 104
Here, a single-crystal silicon layer 102 is formed over the oxide film 101. The single crystal silicon layer 102 is provided with a p-type diffusion layer 105a and an n-type diffusion layer 105b in which p-type impurities and n-type impurities are diffused.
It has become. FIGS. 12A and 12B show two sets of pn junction diodes 1 in order to increase the detection sensitivity of infrared rays.
05 are connected in series by connection wiring 106.
The pn junction diode 105 is connected to the external wiring 111 by the wiring layer 107. This gives p
The change in the electric signal of the n-junction diode 105 depends on the wiring layer 1.
07, and are sent to a signal processing circuit unit (not shown) via the external wiring 111. And such a pn junction diode 1
From the electric signal 05, the amount of infrared rays incident on the infrared detection unit 104 is detected. A cavity (recess) 109 is provided below the infrared detection unit 104, and the infrared detection unit 104
Are supported on the single crystal silicon substrate 100 by support legs 113. Thus, by providing the cavity 109 and thermally insulating the single crystal silicon substrate 100 and the infrared detecting unit 104, the heat capacity of the infrared detecting unit 104 is reduced. Thus, the amount of temperature change of the infrared detector 104 with respect to the amount of incident infrared light can be increased, and the infrared detection sensitivity can be improved.

[0005]

In the thermal infrared detector having the conventional structure, as described above, for example, two sets of pn junction diodes 105 are connected in series in order to enhance the infrared detection sensitivity. The connection wiring 106 was necessary to connect between the pn junction diodes 105. For this reason, the number of pn junction diodes 105 that can be provided in the infrared detector 104 is limited, and there is a certain limit to increasing the sensitivity of the infrared detector by increasing the number of pn junction diodes 105. Further, since the infrared detection unit 104 includes the connection wiring 106, the area of the infrared detection unit 104 has to be increased in some cases, and the heat capacity of the infrared detection unit 104 is increased. As a result, when compared to a bolometer-type thermal infrared detector of the same size or the like, there were problems such as low infrared detection sensitivity and a large thermal time constant.

Accordingly, an object of the present invention is to provide a thermal infrared solid-state imaging device having a thermal infrared detector with a smaller size, a smaller thermal time constant, and a higher sensitivity than a conventional thermal infrared detector. And

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies and have found that the use of a thyristor structure in which a p-type diffusion layer and an n-type diffusion layer are repeatedly formed eliminates connection wiring for connecting between pn junction diodes. I found that I can do it. In particular, the inventors have found that the forward blocking voltage (breakover voltage) can be reduced by increasing the impurity concentration in the pn junction of the thyristor near the junction to which a reverse bias is applied, and completed the present invention.

That is, the present invention provides an infrared solid-state imaging device for detecting an infrared ray incident on the infrared detector by using an infrared detector having a pn junction.
An infrared detection unit supported by a support leg on a concave portion provided in the semiconductor substrate, a pn junction element provided in the infrared detection unit, and both ends connected to both ends of the pn junction element,
A wiring layer for extracting an electric signal from the pn junction element, wherein the pn junction element has a thyristor structure. Thus, by providing the pn junction element having the thyristor structure in the infrared detector, the infrared detector is downsized, and a thermal infrared solid-state imaging device having an infrared detector with a small thermal time constant and a high response speed is obtained. Can be.

[0009] The pn junction element may be a Shockley diode. By using the Shockley diode, the size of the infrared detection unit can be easily reduced.

The Shockley diode has a pn junction surface to which a reverse voltage is applied when a forward voltage is applied to the Shockley diode, and a p-type impurity in a p-type region in contact with the pn junction surface. It is preferable that each of the concentration and the concentration of the n-type impurity in the n-type region is 1 × 10 ¹⁹ cm ⁻³ or more. By using such a structure, the forward blocking voltage required to bring the Shockley diode into the forward conduction state can be reduced.

The pn junction element is an SCR (Silicon Co.)
ntrolled Rectifier). Also by using the SCR, the size of the infrared detection unit can be easily reduced.

Further, according to the present invention, the two support legs are provided substantially symmetrically with respect to the infrared detecting section, and one of the support legs is provided with the wiring layer and the SCR gate wiring layer. The other supporting leg is also an infrared solid-state imaging device provided with a dummy wiring layer having substantially the same shape as the wiring layer and the gate wiring layer and electrically insulated from the SCR. By providing such a dummy wiring layer and making the structure of the support legs substantially symmetrical, the structure of the infrared solid-state imaging device can be strengthened.

The present invention is also an infrared solid-state imaging device in which a plurality of the infrared detectors and a signal processing circuit are provided on the semiconductor substrate. By providing a plurality of infrared detection units in an array, the distribution of infrared light in a two-dimensional plane can be measured, and the detection signal can be output from the signal processing circuit unit. This makes it possible to monolithically form a thermal infrared solid-state imaging device using the infrared detection unit and the signal processing circuit unit.

According to the present invention, an infrared detector including a pn junction element is formed on a semiconductor substrate, and a concave portion is formed in the semiconductor substrate below the infrared detector to support the infrared detector on the concave portion. A method for manufacturing an infrared solid-state imaging device supported by legs, a step of forming an oxide film on a semiconductor substrate,
Forming a single-crystal silicon layer in a predetermined region on the oxide film, forming a pn junction element in the single-crystal silicon layer and forming an infrared detector,
Forming a wiring layer respectively connected to both ends of the junction element, forming a protective film so as to cover the entire surface, etching the semiconductor substrate below the infrared detection unit to form a concave portion, Forming the infrared detecting portion supported on the concave portion by the support leg on the concave portion, wherein the infrared detecting portion forming step includes forming a p-type diffusion layer and an n-type diffusing layer on the single crystal silicon layer.
Forming a pn junction element having a pnpn structure in which the p-type diffusion layer and the n-type diffusion layer are connected at a pn junction surface. It is also a manufacturing method.

Further, the present invention further provides a semiconductor device comprising:
A signal processing circuit portion is formed, and a p-type diffusion layer of the signal processing circuit portion and a p-type diffusion layer of the infrared detection portion are formed in the same step, and / or an n-type diffusion layer of the signal processing circuit portion. And the n-type diffusion layer of the infrared detecting section are formed in the same step. By manufacturing the signal processing circuit unit and the infrared detection unit in the same process, the manufacturing process can be simplified.

Further, the present invention is also a manufacturing method, wherein a plurality of the infrared detecting sections are formed on a semiconductor substrate.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a top view of the infrared detector 103 used in the thermal infrared solid-state imaging device according to the first embodiment of the present invention. FIG.
FIG. 1B is a cross-sectional view taken along the line 1A-1A in FIG. In the thermal infrared solid-state imaging device according to the present embodiment, a plurality of infrared detectors 103 are arranged vertically and horizontally on a semiconductor substrate, as in the thermal infrared solid-state imaging device having the conventional structure in FIG. Connected to the unit.

As shown in FIG. 1B, the thermal infrared detector 103 includes a single crystal silicon substrate 100, and an oxide film 10 such as silicon oxide is formed on the single crystal silicon substrate 100.
1 is provided. At a predetermined position on oxide film 101, single-crystal silicon layer 102 is formed. In the single-crystal silicon layer 102, two pn junction diodes 10 having a p-type diffusion layer 105a and an n-type diffusion layer 105b are provided.
5 are joined at the pn junction surface to form a Shockley diode 120 having a pnpn structure. p
The impurity concentration of each of the diffusion layers 105a and 105b is 1 × 10 ¹⁵ cm ⁻³ or more. The area where the Shockley diode 120 is formed will become the infrared detecting unit 104 in the future. In FIG. 1A, the protective film 108 covering the entire surface is omitted.

Here, a switch element having a pnpn junction structure with respect to a pn junction diode composed of a p-type diffusion layer 105a and an n-type diffusion layer 105b as shown in FIG. 2A is called a thyristor. Figure 2 of the thyristors
As shown in FIG. 2B, a two-terminal thyristor provided with two terminals 301 is called a Shockley diode, and FIG.
As shown in (c), 3
Connect the terminal thyristor to SCR (Silicon Controlled Rectifi
er).

The wiring layer 107 is electrically connected to both ends of the Shockley diode 120 via via holes (not shown). Each wiring layer 107 is connected to an external wiring 111, and is connected to a signal processing circuit unit (not shown).
Connected to.

A concave portion (hollow portion) 109 is formed below the infrared detecting portion 104 by etching. The infrared detecting section 104 is supported on the concave portion 109 by supporting legs 113 which are left substantially symmetrically (point symmetric in FIG. 1A) on both sides of the infrared detecting section 104. As described above, the infrared detecting unit 104 is supported by being floated on the recess 109, and the infrared detecting unit 104 and the single crystal silicon substrate 100 are thermally insulated. Accordingly, the heat capacity of the infrared detection unit 104 is reduced, the temperature change of the infrared detection unit 104 with respect to the incident amount of infrared light can be increased, and the detection sensitivity of infrared light can be improved. Two support legs 1
13, a wiring layer 107 is provided.

The upper surface of the infrared detector 103 is covered with a protective film 108 such as silicon oxide. The protective film 10
Reference numeral 8 also serves to prevent etching of the single crystal silicon layer 102 on which the Shockley diode is formed when the single crystal silicon substrate 100 is etched to form the recess 109.

A plurality of infrared detectors 103 and a signal processing circuit section (not shown) are formed on a silicon substrate 100 to provide a thermal infrared solid-state imaging device as shown in FIG. Note that the p-type diffusion layer 105a of the infrared detector 103,
By forming the n-type diffusion layer 105b, the p-type diffusion layer such as a transistor formed in the signal processing circuit portion, and the n-type diffusion layer in the same process, the manufacturing process can be simplified.

Next, the operation principle of the infrared solid-state imaging device shown in FIG. 1 will be described. In the infrared detector 103 of the infrared solid-state imaging device, the infrared light incident on the infrared detection unit 104 raises the temperature of the infrared detection unit 104, and the temperature of the pn junction diode 105 constituting the Shockley diode 120 changes. The current-voltage characteristic of one pn junction diode changes according to the following equation 1.

[0025]

I = I ₀ [exp (qV / kT) −1] (Equation 1)

Here, I is current, I ₀ is saturation current, V is bias voltage, T is temperature, k is Boltzmann's constant, and q is elementary charge. Under the constant current I, the sensitivity of the bias voltage to the temperature is about 1.4 (mV / K).

As shown in the equation 1, as the temperature changes, p
Since the bias voltage applied to both ends of the n-junction diode changes, the amount of infrared light incident on the infrared detector 103 can be detected by reading the change in the bias voltage by the signal processing circuit.

Next, referring to FIG.
20 shows the current-voltage characteristic of No. 20. FIG. 4 shows the state of the energy band in each operation state of the Shockley diode 120. FIG. 4A shows a thermal equilibrium state, and FIG.
4B illustrates a forward blocking state, FIG. 4C illustrates a forward conducting state, and FIG. 4D illustrates a backward blocking state.

At the time of infrared detection, a forward bias voltage is applied to the Shockley diode 120 through the wiring layer 107 so that a current equal to or larger than a holding current for maintaining a forward conduction state flows. That is, FIG.
The forward conduction state of (c) is maintained. In the forward conduction state, most of the applied voltage is applied as a forward bias to the junctions J1 and J3, and a diffusion current mainly flows through the junctions J1 and J3. On the other hand, a drift current flows through the junction J2. Therefore, the Shockley diode 120 can be regarded as equivalent to a conventional semiconductor junction element in which two pn junction diodes 105 are connected in series by the wiring 106. That is, the thermal infrared detector 103 of the thermal infrared solid-state imaging device shown in FIG. 1 has the same infrared detection sensitivity as the thermal infrared detector 103 having the conventional structure shown in FIG.

In the infrared detector 103 of the thermal infrared solid-state imaging device according to the present embodiment, the pn junction diode 1 is used.
05 connected at the pn junction surface
20 so that the connection wiring 106
Infrared detector 1 equivalent to conventional structure without forming
03 can be formed. Therefore, the area of the infrared detection unit 104 can be reduced, and the thermal infrared solid-state imaging device can be reduced in size. In addition, the infrared detector 1
Since the heat capacity of the infrared detection unit 104 is reduced and the thermal time constant is reduced as the size of the infrared detector
04 becomes faster.

In place of the Shockley diode, the same two-terminal thyristor, SSS (Silicon Symm
etrical Switch) can also be used.

Here, the p-type diffusion layer 105a, the n-type diffusion layer 105b, the p-type diffusion layer 105a, and the n-type diffusion layer 105b
A Shockley diode 120 having a four-layer structure of
Although the case of using the infrared detection unit 104 has been described, more diffusion layers can be provided. n p
In the Shockley diode 120 in which the n-junction diode 105 is connected in series by the pn-junction surface, when the temperature of the pn-junction diode 105 changes while the forward conduction state is maintained, the current-voltage characteristic is expressed by the following equation (2). It changes according to.

[0033]

I = I ₀ [exp (qV / nkT) −1] (Equation 2)

Here, n is the number of pn junction diodes 105. In this case, under the constant current I, the sensitivity of the bias voltage to the temperature is about 1.4n (mV / K), and the number n of the pn junction diodes 105 connected in series is n.
Is proportional to Therefore, three or more pn junction diodes 1
By using the Shockley diode 120 connected in series with each other, the detection sensitivity of infrared rays can be further improved.

FIG. 5 shows nine pn junction diodes 105.
Detector 10 connected in series through a pn junction surface
FIG. 5A is a top view, and FIG.
It is sectional drawing of 5A-5A direction of (a). FIG.
Connects nine pn junction diodes 105 to the connection wiring 106
FIG. 6A is a top view, and FIG. 6B is a cross-sectional view in the 6A direction. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

Each of the infrared detectors 103 shown in FIGS. 5 and 6 has nine pn junction surfaces contributing to the detection of infrared rays, and thus has the same infrared detection sensitivity. However, FIG.
In the infrared detector 103 having the conventional structure, each pn
It is necessary to provide the connection wiring 106 between the junction diodes 105, and the connection wiring 106 and the wiring layer 10
A total of 18 via holes 112 are required to connect 7 with the pn junction diode 105. On the other hand, in the infrared detector 103 according to the present embodiment in FIG. 5, the connection wiring 106 is unnecessary for the connection between the respective pn junction diodes 105, and the wiring layer 107 and the pn junction diode 105 are connected. The number of via holes 112 is also two. For this reason, in the infrared detector 103 according to the present embodiment, the thickness of the pn junction diode 105 can be reduced and integrated at a high density.
4 have the same area, the conventional infrared detector 1
It is possible to increase the number of pn junction surfaces contributing to the detection of infrared rays as compared with 03 and improve the detection sensitivity. Conversely,
In order to obtain the same detection sensitivity, the area of the infrared detecting unit 104 may be smaller than that of the related art.
4 can be reduced in size, and the heat capacity of the infrared detection unit 104 can be reduced. Thereby, as compared with the conventional structure, the individual infrared detectors 103 can be reduced in size, the thermal infrared solid-state imaging device itself can be reduced in size, and the thermal time constant of the infrared detector 103 can be reduced. The response time to a temperature change can be shortened.

Embodiment 2 FIG. 7 is a top view of the infrared detector 103 used in the thermal infrared solid-state imaging device according to the second embodiment of the present invention. FIG. 7 (b)
It is sectional drawing of 7A-7A direction of FIG. 7 (a). In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In the thermal infrared solid-state imaging device according to the present embodiment, a plurality of infrared detection units 103 are vertically and horizontally arranged on a semiconductor substrate, similar to the thermal infrared solid-state imaging device having the conventional structure in FIG. Connected to the unit.

The infrared detector 103 according to the present embodiment
In the figure, a Shockley diode 120 is formed in the infrared detection unit 104. Further, near the pn junction interface where a reverse voltage is applied when a forward voltage is applied to the Shockley diode 120, the high concentration diffusion layer 10 is formed.
5a1 and 105b1 are provided. That is, the Shockley diode 120 has a pn junction surface to which a reverse voltage is applied when a forward voltage is applied, and the concentration of the p-type impurity in the p-type diffusion layer 105a in contact with the pn junction surface and n The concentration of the n-type impurity in the type diffusion layer 105b is 1 × 10 ¹⁹ cm ⁻³ or more. In FIG. 7, p
Sandwiched between the n-type diffusion layer 105a and the n-type diffusion layer 105b.
High concentration p-type diffusion layer 105a1, high concentration n-type diffusion layer 105
The impurity concentration of b1 is 1 × 10 ¹⁹ cm ⁻³ or more. Further, since there are the high-concentration p-type diffusion layer 105a1 and the high-concentration n-type diffusion layer 105b1, the p-type diffusion layer 105a
Alternatively, even if one of the n-type diffusion layers 105b is omitted,
The characteristics of the pn junction diode 105 remain unchanged, and higher integration is possible.

The current-voltage characteristics of the Shockley diode 120 of the present invention and the state of the energy band in each operating state are the same as those in FIGS. 3 and 4 of the first embodiment.
However, in the present embodiment, the Shockley diode 12
High-concentration p-type diffusion layer 105a sandwiching the zero pn junction J2
1. Since the impurity concentration of each of the high-concentration n-type diffusion layers 105b1 is 1 × 10 ¹⁹ cm ⁻³ or more, Zener breakdown occurs at the junction J2 with a low bias, and the potential difference on both sides of the junction J2 decreases due to the hook effect. . That is, by applying a low bias, it is possible to shift from the state of FIG. 4B to the forward conduction state of FIG. 4C which is an infrared detection state, and the forward blocking voltage (break) required for such a shift. Overvoltage) can be kept low.

In this embodiment, the case where the Shockley diode 120 having four diffusion layers is used has been described. However, by using four or more diffusion layers, infrared rays having higher infrared ray detection sensitivity can be obtained. It is also possible to form a detector. FIG. 8 shows an infrared detector 103 in which nine pn junction diodes 105 are connected in series via a pn junction surface, similarly to FIG. 5, and FIG.
FIG. 8B is a sectional view taken along the line 8A-8A in FIG. Further, in FIG. 8, the junction near the interface between the pn junction diode 105, the impurity concentration of 1 × 10 ¹⁹ cm ^-3 or more of the high-concentration p-type diffusion layer 105 a 1, a high concentration n-type diffusion layer 105
b1 is provided. High concentration p-type diffusion layer 105a1,
Each of the high-concentration n-type diffusion layers 105b1 has a thickness of 0.0
It is preferably 1 μm or more. FIG. 8 (a)
(B) is a case where the p-type diffusion layer 105a is omitted without being formed, and further high integration is achieved by using such a structure.

As described above, the plurality of pn junction diodes 1
The use of the Shockley diode 120 made of 05 makes it possible to improve the detection sensitivity of infrared rays. A high-concentration p-type diffusion layer 105a1 and a high-concentration n-type diffusion layer 1 are formed at the connection interface between the pn junction diodes 105.
By providing 05b1, the bias voltage required for shifting to the forward conduction state can be reduced.

Embodiment 3 FIG. 9 is a top view of the infrared detection unit 103 used in the thermal infrared solid-state imaging device according to the third embodiment of the present invention. FIG. 9 (b)
It is sectional drawing of 9A-9A direction of FIG. 9 (a). In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. The infrared detector 103 according to the present embodiment includes an SCR 121 instead of the Shockley diode 120 according to the first embodiment.
Is used. The SCR 121 is a p-type diffusion layer 105
a, n-type diffusion layer 105b, p-type diffusion layer 105a, and n-type diffusion layer 105b have a pnpn structure, and both ends thereof are electrically connected to wiring layer 107, respectively. Furthermore,
Central p-type diffusion layer 1 not connected to wiring layer 107
The gate wiring 114 is electrically connected to one of the gate electrode 05a and the n-type diffusion layer 105b. FIG. 9 shows a case where the gate wiring 114 is connected to the p-type diffusion layer 105a.

On both sides of the infrared detecting section 104, the supporting legs 113 are substantially symmetric (point symmetric in FIG. 9A).
Is provided. One of the two support legs 113 is provided with a wiring layer 107 and a gate wiring layer 114. On the other hand, the other support legs 113 have substantially the same shape as the wiring layer 107 and the gate wiring layer 114, but have the SCR 121
And a dummy wiring layer 115 electrically insulated from the dummy wiring layer 115 is provided. Thus, by making the structure of the support leg 113 substantially symmetric, the structure of the infrared detector 113 can be strengthened. In the case of a thyristor requiring two gate terminals 114, the dummy wiring layer 115 can be electrically connected to the thyristor and used as a gate wiring layer.

Next, the operation principle of the infrared solid-state imaging device shown in FIG. 9 will be described. SCR of infrared detector 104
A forward bias voltage is applied to both ends of the switch 121 such that a current equal to or greater than a holding current for maintaining the forward conduction state flows. When infrared light enters the infrared detection unit 104, the temperature of the infrared detection unit 104 changes,
Accordingly, the current-voltage characteristics of the SCR 121 change. As a result, the forward bias voltage changes according to the above equation (2). Therefore, by reading the change in the bias voltage caused by this temperature change in the signal processing circuit section, the amount of infrared light incident on the thermal infrared detector 103 can be detected.

FIG. 10 shows the current-voltage characteristics of the SCR 121. As shown in FIG. 10, the current-voltage characteristic of the SCR 121 is such that no current flows through the gate wiring 114 (I
_g0 ) is the same as the current-voltage characteristic of the Shockley diode 120 shown in FIG. On the other hand, when the current flowing through the gate wiring 114 is increased (for example, _Ig3 ),
The forward blocking voltage decreases.

The SCR 121 is used for infrared detection in a forward conduction state similar to the state shown in FIG. In this state, most of the applied voltage is applied to the junctions J1 and J3 as a forward bias, and the diffusion current mainly flows through the junctions J1 and J3. A drift current flows through the junction J2. Therefore, the SCR 121 can be regarded as equivalent to a case where two pn junction diodes 105 are connected in series by the connection wiring 106. Therefore, the thermal infrared detector 103 shown in FIG. 9 has the same infrared detection sensitivity as that of the conventional infrared detector 103 shown in FIG. Further, since the pn junction diodes 105 are connected not through the connection wiring but through the pn junction surface, the infrared detection unit 104 can be reduced in size. In the present embodiment, the SCR 121 is used. By introducing a current from the gate terminal, the forward blocking voltage can be controlled to be low. Further, by controlling the current introduced to the gate terminal, the SCR 121 can be switched from the forward blocking state (FIG. 4B) to the forward conducting state (FIG. 4C). Instead of SCR,
GTO (Gate Turn Off th
yristor) can be used, in which case not only switching from the forward blocking state to the forward conducting state, but also vice versa.
Therefore, for example, as shown in FIG. 11, when a plurality of infrared detectors 103 are provided on the silicon substrate 100, it is possible to read out only the signal of the infrared detector 103 arbitrarily selected. In other words, as before,
Of the signals sent from all the infrared detectors 103, only the necessary signal need not be selected by the signal processing circuit unit, and the signal processing circuit unit can be simplified.

In place of the SCR, the same GTO (GateTurn Off thyristor) is used as the same three-terminal thyristor.
In addition to r), a reverse conducting thyristor, a reverse conducting GTO thyristor, a triac, or the like can be used. Also, 3
Instead of the terminal thyristor, two gate wiring layers 114
SCS (Silicon Co.)
ntrolled Switch) can also be used.

In FIG. 9, S having four diffusion layers
The infrared detector 103 using the CR has been described.
It is also possible to use four or more diffusion layers connected via a pn junction surface. By using such a structure,
Further, the detection sensitivity of infrared rays can be improved.

[0049]

As is apparent from the above description, the infrared solid-state imaging device according to the present invention has a p-type thyristor structure.
By providing the n-junction element in the infrared detector, a thermal infrared solid-state imaging device having an infrared detector with a small thermal time constant and a high response speed can be obtained.

Further, the downsizing of the infrared detector makes it possible to downsize the thermal infrared solid-state imaging device.

Further, the pn junction diode which is highly integrated can provide more pn junction surfaces contributing to infrared detection by the high integration, and a thermal infrared solid-state imaging device having a high sensitivity infrared detector can be obtained.

When a Shockley diode is used for the infrared detector, by providing a high concentration diffusion layer,
The forward blocking voltage can be kept low.

When an SCR is used for the infrared detector, only the signal from the arbitrarily selected infrared detector can be output because the SCR has a switching function.

Further, in the manufacturing method according to the present invention, since the diffusion layer of the infrared detecting section and the diffusion layer of the signal circuit section are formed in the same step, the manufacturing steps can be simplified.

[Brief description of the drawings]

FIG. 1 is an infrared detector of a thermal infrared solid-state imaging device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a pn junction diode, a Shockley diode, and an SCR.

FIG. 3 is a current-voltage characteristic of the Shockley diode according to the first embodiment of the present invention.

FIG. 4 is an energy band diagram in each operating state of the Shockley diode according to the first embodiment of the present invention.

FIG. 5 is an infrared detector of another thermal infrared solid-state imaging device according to the first embodiment of the present invention;

FIG. 6 is an infrared detector of a thermal infrared solid-state imaging device according to a conventional structure.

FIG. 7 is an infrared detector of the thermal infrared solid-state imaging device according to the second embodiment of the present invention;

FIG. 8 is an infrared detector of another thermal infrared solid-state imaging device according to the second embodiment of the present invention;

FIG. 9 is an infrared detector of the thermal infrared solid-state imaging device according to the third embodiment of the present invention;

FIG. 10 is a current-voltage characteristic of the SCR according to the third embodiment of the present invention.

FIG. 11 is a thermal infrared solid-state imaging device according to a conventional structure.

FIG. 12 is an infrared detector of a thermal infrared solid-state imaging device according to a conventional structure.

[Explanation of symbols]

Reference Signs List 100 single-crystal silicon substrate, 101 oxide film, 102
Single crystal silicon layer, 103 infrared detector, 104
Infrared detector, 105 pn junction diode, 105a
p-type diffusion layer, 105b n-type diffusion layer, 105a1 high-concentration p-type diffusion layer, 105b1 high-concentration n-type diffusion layer, 10b1
6 connection wiring, 107 wiring layer, 108 protective film, 109
Cavity (recess), 110 etching hole, 111 external wiring, 112 via hole, 113 support leg, 114
Gate wiring layer, 115 dummy wiring layer, 120 Shockley diode, 121 SCR, 201 signal processing circuit section, 202 detector array.

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Claims (9)

[Claims] 1. An infrared solid-state imaging device for detecting infrared light incident on an infrared detection unit using an infrared detection unit having a pn junction, comprising: a semiconductor substrate; An infrared detector supported by the support leg, a pn junction element provided in the infrared detector, a wiring layer connected to both ends of the pn junction element and extracting an electric signal from the pn junction element, Wherein the pn junction element has a thyristor structure. 2. The infrared solid-state imaging device according to claim 1, wherein the pn junction element is a Shockley diode. 3. The p-type Shockley diode having a pn junction surface to which a reverse voltage is applied when a forward voltage is applied to the Shockley diode, and a p-type region in contact with the pn junction surface. 3. The infrared solid-state imaging device according to claim 2, wherein the concentration of the impurity and the concentration of the n-type impurity in the n-type region are each 1 × 10 ¹⁹ cm ⁻³ or more. 4. The infrared solid-state imaging device according to claim 1, wherein the pn junction element is an SCR. 5. The infrared detecting section, wherein the two supporting legs are provided substantially symmetrically, one of the supporting legs is provided with the wiring layer and the gate wiring layer of the SCR, and the other is provided with the other. 5. The infrared solid-state imaging device according to claim 4, wherein a dummy wiring layer having substantially the same shape as the wiring layer and the gate wiring layer and electrically insulated from the SCR is provided on the support leg. . 6. The infrared solid-state imaging device according to claim 1, wherein a plurality of the infrared detection units and a signal processing circuit unit are provided on the semiconductor substrate. 7. An infrared detector including a pn junction element is formed on a semiconductor substrate, a recess is formed in the semiconductor substrate below the infrared detector, and the infrared detector is supported on the recess by a support leg. A method for manufacturing an infrared solid-state imaging device, comprising: a step of forming an oxide film on a semiconductor substrate; a step of forming a single-crystal silicon layer in a predetermined region on the oxide film; and a pn junction element in the single-crystal silicon layer. Forming an infrared detecting section, forming an infrared detecting section, forming wiring layers respectively connected to both ends of the pn junction element, forming a protective film so as to cover the entire surface, Forming a concave portion by etching the semiconductor substrate below the infrared detecting portion, and forming the infrared detecting portion supported by a support leg on the concave portion, wherein the infrared detecting portion forming step includes: For single crystal silicon layer Forming a diffusion layer and the n-type diffusion layer, pn of pnpn structure and the p-type diffusion layer and the n-type diffusion layer is connected at the pn junction surface
A method for manufacturing an infrared solid-state imaging device, which is a step of forming a bonding element. 8. A signal processing circuit portion is formed on the semiconductor substrate, and a p-type diffusion layer of the signal processing circuit portion and a p-type diffusion layer of the infrared detection portion are formed.
The n-type diffusion layer of the signal processing circuit unit and the n-type diffusion layer of the infrared detection unit are formed in the same step. 8. The production method according to 7. 9. The manufacturing method according to claim 7, wherein a plurality of the infrared detection units are formed on a semiconductor substrate.