JP2002299703A - Thermal infrared detecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal infrared detecting element that can obtain an appropriate temperature characteristic, at a temperature higher than the room temperature. SOLUTION: This thermal infrared detecting element is provided with an insulation foundation layer 8 having a crystal structure and a bolometer thin film 9 grown epitaxially on the layer 8. The thin film 9 is composed of a material expressed by the chemical formula of Ca2-x Srx RuO4-d (where, 0<=x<=0.05 and (d) denotes a value indicating the deviation from stoichiometry of oxygen) and has a lattice constant, which is different from that of the foundation layer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal infrared detecting element using a bolometer thin film.

[0002]

2. Description of the Related Art As a thermal type infrared detecting element used in an infrared camera or the like, an element using a bolometer thin film made of vanadium oxide has been known (for example, R.I.
Murphy, et al., Proc. SPIE, 4028, p. 12 (2000)
). This bolometer thin film is formed by a sputtering method, and is a polycrystalline body having a random orientation and composed of a mixture of VO ₂ , V ₂ O ₃ and V ₂ O ₅ . The performance of the bolometer is evaluated by the temperature dependence coefficient TCR of the resistance expressed by TCR = (1 / R) (dR / dT) (1). The vanadium oxide has a TCR of about 2-3%.

However, as the thermal infrared detecting element, a more sensitive element, that is, a bolometer material having a larger TCR value is required. Particularly, at present, the pixel pitch is being reduced in order to reduce the cost and increase the resolution. However, as the pixel pitch becomes smaller, a higher TCR value is required to obtain the same camera sensitivity. Where the camera sensitivity is Noise Equivalent Temperature Differenc
e, short for NETD.

On the other hand, as a material having an extremely high TCR, a material using a metal-insulator phase transition of a VO ₂ single phase film has been studied (CD Reintsema et al., Proc. SPIE 3698 , p. 1).
90 (1999)). In this case, a very high value of TCR = 200 to 400% is obtained. However, there are disadvantages in that the TCR value is too large and thermal noise is large, and the transition is too steep to obtain a uniform TCR characteristic over the entire sensor.

[0005] Further, Mn perovskite oxide has a high TCR.
Studies have been conducted to obtain a value, but a TCR value of 3% or more at room temperature has not yet been obtained.

Further, Japanese Patent No. 3087645 discloses a semiconductor ceramic composition having a negative sudden change resistance temperature characteristic made of an LnNi-based oxide (where Ln is a rare earth element other than La and Ce or Bi). . However, since the TCR value is too large and the transition is too steep, there is a disadvantage that thermal noise is large and it is difficult to obtain uniform characteristics over a wide temperature range even when applied to an infrared sensor. Also,
It describes only bulk materials, and does not describe a thin film form useful as an electronic device.

[0007] Also, a thin film of NdNiO ₃ has been proposed (G. Catalan et al., Phys. Rev. B, 62 , p.
7892 (2000)). This document states that the metal-insulator phase transition temperature is lowered by the epitaxial strain from the substrate, and that the temperature dependence of the resistance due to the phase transition becomes gentler than that of the bulk. However, since this substance has a phase transition temperature of 200 K or less and a small TCR near room temperature, it cannot be applied to an uncooled thermal infrared detector.

[0008]

As described above, thermal infrared detecting elements using various bolometer materials have been proposed. In particular, a bolometer material using a metal-insulator phase transition has been proposed from the viewpoint of increasing the temperature dependence coefficient TCR of resistance. However, there are problems that the phase transition is too steep to obtain uniform characteristics and that the phase transition temperature is too low to be used at room temperature or higher. Could not be said to have.

The present invention has been made to solve the above-mentioned conventional problems, and has as its object to provide an infrared detecting element capable of obtaining appropriate temperature characteristics at room temperature or higher.

[0010]

SUMMARY OF THE INVENTION A thermal infrared detecting element according to the present invention includes a thermal infrared detecting element having an insulating underlayer having a crystal structure and a bolometer thin film epitaxially formed on the underlayer. The bolometer thin film has a chemical formula of Ca _2-x Sr _x RuO _4-d (where 0
.Ltoreq.x.ltoreq.0.05, where d is a value representing the deviation of oxygen from stoichiometry), and has a distortion based on a difference in lattice constant from the underlayer. .

The substance used for the bolometer thin film undergoes a phase transition between a metal phase and an insulator phase in accordance with the temperature (the high-temperature side is a metal phase and the low-temperature side is an insulator phase). The change is steep, and it is difficult to apply to an infrared detecting element. In the present invention, the substance is epitaxially grown on an underlayer to form a thin film,
A strain (epitaxial strain) based on a difference in lattice constant from the underlayer is generated, and a change in resistance due to a phase transition can be moderated. In the bulk state, x is about 0.037.
The phase transition temperature becomes higher than room temperature (about 300 K or higher) in the following cases. However, since the phase transition temperature can be increased by generating epitaxial strain, x is about 0.05 or less when the film is thinned. In this case, the phase transition temperature can be increased to room temperature or higher, and the infrared detection operation can be performed at room temperature or higher. The value of d representing the deviation of oxygen from stoichiometry is usually about -0.1 or more and about 0.2 or less.

The phase transition temperature of the substance used for the bolometer thin film is rather low. In addition, the substance is distorted in a direction in which the crystal lattice extends in a plane parallel to the interface between the underlayer and the bolometer thin film, so that the phase transition temperature increases. Therefore, the interface of two crystal axes parallel to the underlayer and the bolometer thin film, the lattice constant in the bulk state of the underlayer was a _s and b _s, the lattice constant in the bulk state of the bolometer thin film and a _b and b _b when, (a _s +
By making b _s ) larger than ( _ab + b _b ), the phase transition temperature can be increased. However, (a _s + b _s)
There (a _b + _{b b)} is too large than, the temperature dependence coefficient TCR of the resistance becomes smaller, a certain or more TCR (TCR
= To ensure 4% or _{more), (a s + b s)} / (a b +
Preferably, the value of b _b ) is less than or equal to about 1.014.

An electrode layer is connected to the bolometer thin film. To accurately detect a change in resistance of the bolometer thin film, the resistance of the electrode layer itself and the contact resistance between the bolometer thin film and the electrode layer are reduced. It is desirable. For this purpose, it is desirable to lower the phase transition temperature of the bolometer thin film in the portion in contact with the electrode layer (that is, to make the phase transition from a lower temperature to the metal phase) to stabilize the metal phase. On the other hand, the substance used for the bolometer thin film is distorted in a direction in which the crystal lattice shrinks in a plane parallel to the interface between the electrode layer and the bolometer thin film, thereby lowering the phase transition temperature.

Therefore, a bolometer thin film is epitaxially grown not only on the underlayer but also on a conductive electrode layer having a crystal structure, and the bulk of the electrode layer is moved with respect to two crystal axes parallel to the interface between the electrode layer and the bolometer thin film. when the lattice constant in the state was a _e and b _e, the lattice constant in the bulk state of the bolometer thin film and a _b and _{b b, (a e + b} e)
The (a _b + _{b b)} to be smaller than than, it is possible to lower the phase transition temperature, as a result, it is possible to lower the resistance of the metal phase described above to stabilize. However, (a
When _e + b _e) is (a _b + _{b b)} is too small than, because it may reverse the resistance _{increases, (a e + b e)} / (a b +
Preferably, the value of b _b ) is greater than or equal to about 0.975.

A thermal infrared detecting element according to the present invention is a thermal infrared detecting element comprising an insulating base layer having a crystal structure and a bolometer thin film epitaxially formed on the base layer. , The bolometer thin film comprises:
The chemical formula is RNiO _3-d (where R is a single or a plurality of rare earth elements and the average ion radius when converted into a trivalent ion is 0.121 nm or more and 0.125 nm or less, and d is the deviation of oxygen from stoichiometry. And a distortion based on a difference in lattice constant from the underlying layer.

In the present invention, for the same reason as described above, the material used for the bolometer thin film is epitaxially grown on the underlayer to cause epitaxial strain, so that the resistance change due to the phase transition becomes gentle. I have to. Further, the average ionic radius of the rare earth element when it becomes trivalent ion (when the rare earth element represented by R is single, the ionic radius of the rare earth element, and when the rare earth element represented by R is plural, Is smaller than about 0.121 nm if the ionic radius of each of the plurality of rare earth elements according to the composition ratio of the plurality of rare earth elements is less than about 0.121 nm.
If no insulator phase transition occurs and is greater than about 0.125 nm, the phase transition temperature will be lower than room temperature. Therefore,
When the average ionic radius is in the above range, the metal-insulator phase transition can be performed, the phase transition temperature can be set to room temperature or higher, and the infrared detection operation can be performed at room temperature or higher. The value of d representing the deviation of oxygen from stoichiometry is usually about -0.1 or more and about 0.2 or less.

The phase transition temperature of the substance used for the bolometer thin film is rather high. In addition, the substance is distorted in a direction in which the crystal lattice extends in a plane parallel to the interface between the underlayer and the bolometer thin film, so that the phase transition temperature decreases. Therefore, if you define a lattice constant similar to the previous invention, is made larger than the _{(a s + b s) (} a b + b b), it can be lowered phase transition temperature. However, if (a _s + b _s) is too large than (a _b + _{b b),}
Since the temperature dependence coefficient TCR of the resistance becomes small, to ensure a certain or more TCR (TCR = 4% or more), (a _s
It is preferred that the value of + b _s ) / ( _ab + b _b ) be less than or equal to about 1.024.

Also, in the present invention, a bolometer thin film is epitaxially grown not only on the underlayer but also on a conductive electrode layer having a crystal structure, similarly to the above invention, and the lattice constant is defined in the same manner as in the above invention. In this case, by making (a _e + b _e ) larger than ( _ab + b _b ), the phase transition temperature can be lowered, and the metal phase can be stabilized and the resistance can be lowered. However, (a _e + b _e) is (a _b +
When b _b) is too large than, because it may reverse the resistance increases, the value of _{(a e + b e) /} (a b + b b) about 1.02
It is preferably 1 or less.

Further, a thermal infrared detecting element according to the present invention is a thermal infrared detecting element comprising an insulating underlayer having a crystal structure and a bolometer thin film epitaxially formed on the underlayer. , The bolometer thin film comprises:
The chemical formula is RBaCo ₂ O _{5 + d} (where R is a single or a plurality of rare earth elements and the average ion radius when converted to a trivalent ion is 0.108 nm or more, and d is the deviation of oxygen from stoichiometry. Characterized by having a distortion based on a difference in lattice constant from the underlayer.

In the present invention, for the same reason as described above, the material used for the bolometer thin film is epitaxially grown on the underlayer to cause epitaxial strain, so that the resistance change due to the phase transition becomes gentle. I have to. If the average ionic radius of the rare-earth element trivalent ions is smaller than about 0.108 nm, the phase transition temperature is lower than room temperature. Therefore,
When the average ionic radius is in the above range (about 0.108 nm or more), the phase transition temperature can be set to room temperature or higher, and an infrared detection operation at room temperature or higher can be performed. The value of d representing the deviation of oxygen from stoichiometry is usually about 0 or more and about 0.7 or less. Considering the phase transition at room temperature or higher, the value is about 0.3 or more and about 0.7 or less.

In the material used for the bolometer thin film in the present invention, unlike the above-described invention, the magnitude relationship between the lattice constants of the materials used for the underlayer and the electrode layer and the transition temperature rise and fall are different. There is no clear correlation between them. However, for the undercoat layer, to ensure _{(a s + b s) /} (a b + b b) the value of With and about 1.005 or less to about 0.974 or more, a certain or more TCR (TCR = 3% or more) be able to.
With respect to the electrode _{layer, (a e + b e)} / (a b + b b)
Is about 0.977 or more and about 1.001 or less, the contact resistance between the bolometer thin film and the underlayer can be reduced.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The bolometer thin film used in the embodiment of the present invention includes (a) Ca _2-x Sr _x RuO _4-d system (b) RNiO _3-d system (c) There are three groups of substances of the RBaCo ₂ O _{5 + d} type.

These materials, in bulk state,
Metal at T _MI = 300~410 K - is a substance causing insulator transition. Here, _TMI is a metal-insulator transition temperature, and is defined as a temperature at which the resistance starts to rise sharply with a decrease in temperature when the temperature changes from a high temperature to a phase transition from a metal state to an insulator state. However, the TCR value of these substances due to the metal-insulator transition is too large to be used for a thermal infrared detecting element.

In order to perform infrared detection with higher sensitivity than in the past, it is desirable that approximately 3% ≦ TCR ≦ 40% (2). When the TCR exceeds 40%, thermal noise increases, and a high-performance infrared sensor cannot be obtained.

Further, in order to reduce the cost and increase the resolution, it is desirable that the pixel pitch be smaller than that of the related art, that is, about 15 μm.

On the other hand, NETD of about 60 to 100 mK is desirable because it can be used for various applications. Obtaining NETD = 60 to 100 mK at a pixel pitch of 15 μm is difficult with a conventional vanadium oxide bolometer, and it is desirable that the bolometer sensitivity be about two to three times higher. From this point of view, it is desirable that 4% ≦ TCR ≦ 9% (3).

Further, if a sensor having a sensitivity about 10 times or more higher than that of a conventional sensor is manufactured, a new application which has not been used in the past will be expanded. In this case, it is desirable that approximately 20% ≦ TCR ≦ 30% (4).

For use as an uncooled infrared image sensor, it is necessary to realize these TCR values near room temperature. Actually, since the temperature of the bolometer element rises to room temperature or more due to the bias current when measuring the bolometer resistance, in the temperature range of about 300 to 350 K, the equation (2), preferably the equation (3) or the equation (4) is used. It is desirable to realize the TCR value of the equation.

In order to obtain a necessary TCR value, the present inventor can adjust the TCR value to a value smaller than the maximum value in the bulk and adjust the TCR value to a constant value over a wide temperature range by the effect received from the underlayer. I found what I could do. As an underlayer of the bolometer thin film, a crystal film having uniform insulating orientation is prepared. A bolometer thin film is epitaxially grown thereon. If there is a lattice mismatch between the underlayer and the bolometer material, strain (epitaxial strain) due to the epitaxial effect occurs in the bolometer thin film, and the bolometer thin film has a lattice constant different from the original lattice constant in bulk. As a result, the metal-insulator transition is affected, resulting in a more gradual phase transition than the bulk, and a different _TMI than the bulk. By taking advantage of these phenomena,
Desirable characteristics can be obtained for the thermal infrared detecting element. That is, by providing an appropriate lattice mismatch between the underlayer and the bolometer material, the TCR value satisfying the expression (2) is set to a temperature of 300 at a thin film of each of the substances (a) to (c).
It can be obtained at ~ 350K.

When detecting infrared rays, the resistance of the bolometer is measured. Therefore, it is necessary to form a pair of electrodes. In order to obtain sufficient sensitivity, it is necessary that the resistance value of the electrode portion and the contact resistance between the electrode and the bolometer are sufficiently smaller than the resistance of the bolometer itself. Preferably, it is less than about 1/4, more preferably less than about 1/10. By forming the electrode layer first, depositing a bolometer thin film on it, and selecting the electrode layer so that the metal phase is stable at the bolometer part immediately above the electrode, it is possible to reduce the contact resistance between the electrode and the bolometer. I found it. It has also been found that if there is an appropriate lattice mismatch between the electrode layer and the bolometer material, the metal phase of the bolometer material can be stabilized by epitaxial strain.

In manufacturing an uncooled infrared image sensor, first, a signal readout circuit (R) is provided on a silicon substrate.
ead Out Integrated Circuit, called ROIC)
An electrode layer, a base layer, and a bolometer thin film not mainly composed of silicon are deposited thereon. Then, returning to the silicon process line, processing, deposition, and passivation are performed. Therefore, it is desirable that the material used for the electrode layer, the underlayer, and the bolometer thin film be a material suitable for the silicon process line, which can reduce the manufacturing cost. From such a viewpoint, it is desirable that the elements contained in the electrode layer, the underlayer, and the bolometer thin film are selected from the elements that have already been applied to the silicon process line. In this case, investment for providing a production line different from a normal silicon process line can be omitted, leading to cost reduction. Therefore, it is preferable to select a combination of elements and materials that have been applied to the silicon process line as much as possible for the electrode layer, the underlayer, and the bolometer thin film.

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

An ROIC is formed on a silicon wafer by a normal silicon process, and pixels for detecting infrared rays are formed thereon. The number of pixels is, for example, 320 × 240, and 640 × 480 for applications requiring high resolution. The size of one pixel is between about 50 μm × 50 μm to about 15 μm × 15 μm. Since reducing the chip area leads to cost reduction and increasing demand for high resolution and multiple pixels,
The size of one pixel is preferably about 15 μm × 15 μm. Since the wavelength of infrared light to be detected is about 8 to 14 μm, it is meaningless to reduce the pixel pitch to 10 μm or less due to the problem of diffraction limit.

In each pixel, a hollow structure for thermally separating the bolometer portion is provided. In the present embodiment, the following three types of methods are applied to the method of manufacturing the hollow structure.

The first method is a method of forming a bolometer after depositing a sacrifice layer, and thereafter etching the sacrifice layer to provide a void.

FIG. 1 is a diagram showing the structure of one pixel of an uncooled infrared image sensor manufactured by using the first method. An ROIC is formed on a silicon substrate 1, and a microbridge structure 2 is formed thereon. A gap 3 is formed between the silicon substrate 1 and the microbridge structure 2. The thickness of the gap 3 is about 1/4 of the measurement wavelength 8-14μm.
The wavelength is about 2.5 μm. A foot 4 is connected to the microbridge structure 2 to support the microbridge structure 2 and make electrical contact with a metal wiring 5 for reading a signal and supplying a bias current. Here, P indicates the pixel pitch, and is most preferably about 15 μm.

FIG. 2 is a sectional view of the microbridge and the like along the line AB in FIG. Micro bridge structure 2
Can be obtained by depositing a conductive electrode layer 7 and an insulating base layer 8 on an insulating base substrate 6 and depositing a bolometer thin film 9 thereon.

When infrared rays (IR) enter from above, the temperature of the microbridge rises, and the rise in temperature is detected by a bolometer. The escape of heat from the foot 4 becomes a problem. Further, in the method using the sacrificial layer, the effect of the epitaxial strain is not so remarkably obtained because the crystal orientation of the underlayer on which the bolometer thin film 9 is deposited is not so good.

The second method is SOI (Silicon on Insulato).
r) This method uses a substrate.

FIG. 3 is a diagram showing a cross-sectional structure of one pixel of an uncooled infrared image sensor manufactured by using the second method. Components corresponding to those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

An insulating buffer layer 13 is epitaxially deposited on the single crystal silicon layer 14 on the buried oxide film 11. Thereafter, an insulating underlayer 8 and a conductive electrode layer 7 are epitaxially deposited, and a bolometer thin film 9 is further deposited thereon. After that, the passivation film 12
And finally, the silicon substrate 1 below the buried oxide film 11 is etched to form a void 3.

In this method, on the single crystal silicon substrate 1,
Since all the layers are epitaxially deposited, the effect of the epitaxial strain is sufficiently exhibited. Also, 10 in the figure
Since the bolometer thin film 9 is deposited on the electrode layer 7, the bolometer thin film 9 receives epitaxial strain from the electrode layer 7. By utilizing this property, the metal phase of the bolometer thin film 9 is stabilized at the portion 10 and the contact resistance between the electrode layer 7 and the bolometer thin film 9 can be reduced by reducing the resistance at this portion. However, in this method, the expensive SOI substrate is a bottleneck for cost reduction.

Although FIG. 3 shows a structure in which there is a step between the electrode layer 7 under the bolometer thin film 9 and the underlayer 8, FIG.
As in the example shown in FIG. 1, the surface of the electrode layer 7 under the bolometer thin film 9 and the surface of the base layer 8 may be formed on the same plane. FIG. 3 shows a structure in which the underlayer 8 is deposited under the electrode layer 7 also in the foot 4, but the underlayer 8
It may be a structure without any.

The third method is SON (Silicon on Nothing)
This is a method using a substrate. How to make a SON substrate
"Ichiro Mizushima et al., Applied Physics, October 2000, p. 1187". By forming a trench in the silicon substrate and heat-treating it at about 1100 ° C in a hydrogen atmosphere, a plate-shaped void (Empty Space in Silicon, ESS)
Abbreviation). By utilizing this, a hollow structure for thermal separation is formed.

FIG. 4 is a diagram showing a cross-sectional structure of one pixel of an uncooled infrared image sensor manufactured by using the third method. Components corresponding to those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

First, a void 3 which is an ESS is formed in a single crystal silicon substrate 1. Buffer layer 13 on silicon substrate 1
Is formed epitaxially, an insulating underlayer 8 and a conductive electrode layer 7 are epitaxially deposited, and a bolometer thin film 9 is further deposited thereon. Thereafter, the whole is covered with a passivation film 12, and the foot 4 and the microbridge are separated by etching.

Although FIG. 4 shows an example in which the buffer layer 13 is first formed on the single crystal silicon substrate 1, the underlayer 8 may be formed directly on the silicon substrate 1 without the buffer layer 13. Further, FIG. 4 shows a structure in which the underlayer 8 is deposited under the electrode layer 7 also in the foot 4, but a structure in which the underlayer 8 is not provided in the foot 4 may be adopted.

Although three methods have been described above, considering the simplicity of the processing process and the deposition process, the laminated structure as shown in FIG. 4 is the least expensive. In this method, all the layers are epitaxially deposited on the single crystal silicon, so that the effect of the epitaxial strain is sufficiently exhibited. Also, the manufacturing cost of the SON substrate is lower than that of the SOI substrate. Therefore, it can be said that the third method shown in FIG. 4 is the most desirable among the above three methods.

Next, the epitaxial strain that the bolometer thin film receives from the underlayer will be described below.

FIG. 5 shows the relationship between the lattice constants when a bolometer thin film is epitaxially grown on the underlayer. 31
Represents the crystal lattice of the underlayer, and 32 represents the crystal lattice of the bolometer material.

[0051] The lattice constants of the two-dimensional crystal lattice of the underlying layer surface, and a _s and b _s. The bulk lattice constants of the bolometer material in epitaxial relation with these are given by a _b and b _b
And These lattice constants are described below for all materials in the primitive cell of perovskite oxide (pr
Take the lattice spacing that matches the imitive cell). The magnitude of the lattice mismatch is represented by the following equation.

[0052] a direction of lattice mismatch _{LM a (%) = ((} a s -a b) / a b) × 100 (5) b direction lattice mismatch _{LM b (%) = ((} b s -b _{b) / b b) × 100} (6) average lattice mismatch _{LM AV (%) = ((} (a s + b s) - (a b + b b)) / (a b + b b)) × 100 (7) Temperature dependence of resistance of bolometer thin films deposited on various substrates and underlayers was investigated. As a result, the conditions for obtaining a desirable TCR value by the effect of epitaxial strain were found as follows.

(1) It is desirable that the absolute value of the average lattice mismatch is about 10% or less. If the lattice mismatch is larger than this, the metal-insulator phase transition becomes too gradual, making it difficult to obtain the required TCR value.

(2) It is desirable that the absolute value of the lattice mismatch in either the a direction or the b direction is about 0.4% or more. If the lattice matching is better than this, the metal-insulator transition becomes so steep as to be close to the case of bulk, the TCR value becomes too large, and it becomes difficult to obtain uniform characteristics in the sensor. Also, if the lattice matching is too good, the metal-insulator transition may have hysteresis,
This is also not suitable for bolometers.

(3) The bolometer film thickness is desirably about 20 nm or more and about 200 nm or less. Outside this range, it is difficult to obtain the effect due to the epitaxial strain.

(4) It is desirable that the absolute value of the average lattice mismatch is about 2.5% or less. In this case, a desirable TCR value of about 4 to 9% is easily obtained.

(5) It is desirable that the absolute value of the lattice mismatch in either the a direction or the b direction is about 0.6% or more. In this case, a desirable TCR value of about 4 to 9% is easily obtained.

(6) When the bolometer film thickness is about 60 nm or more, the effect due to the epitaxial strain is easily obtained.

The effect of the epitaxial strain will be supplemented. The substance handled in the present invention is grown with a lattice constant different from that of the bulk under the stress from the substrate to a critical thickness of about 40 to 50 nm. When the thickness exceeds the critical thickness, the strain is relaxed and approaches the bulk lattice constant. Therefore, when a film that is slightly thicker than the critical film thickness is formed, there are a portion that has a property different from that of the bulk due to the effect of the epitaxial strain, and a portion that is close to the bulk without being affected by the effect. result,
As a whole, a metal-insulator phase transition that is more gradual than bulk occurs.

The effect of the epitaxial strain on the bolometer thin film from the electrode layer will be described. The bolometer material used in the present invention has a slight change in the crystal structure before and after the metal-insulator phase transition. Therefore, depending on how the epitaxial strain is received, the metal phase can be more stabilized than the insulator phase. By appropriately selecting the lattice constant of the electrode layer, the metal phase can be more stabilized than the insulator phase in the portion immediately above the electrode layer in the bolometer thin film.
As a result, the contact resistance between the electrode and the bolometer can be reduced. The conditions for obtaining a low contact resistance by the effect of epitaxial strain were found as follows.

[0061] (1) using a lattice constant of the electrode layer, an average lattice mismatch LM _AV ⁱ in the average lattice mismatch LM _AV ^m and the insulator phase in the metal phase of the ^{_{bolometer, | LM AV m | <|}} LM _AV ⁱ |
It is desirable to select an electrode layer such that

(2) It is desirable that the absolute value | LM _AV ^m | of the average lattice mismatch is about 10% or less. If the lattice mismatch is larger than this, the crystallinity of the bolometer thin film decreases, and the resistivity tends to increase.

The bolometer material will be described. In order to perform highly sensitive infrared detection, it is necessary that 3% ≦ TCR ≦ 40% (see Equation 5) in a temperature range of 300 to 350K. Therefore, when the temperature is lowered from a high temperature, the metal defined as the temperature at which the resistance starts to rise rapidly from the metal state
Desirably, the insulator transition temperature _TMI is about 300 K or more, more preferably about 350 K or more.

The present inventors have focused on Ca ₂ RuO ₄ as a bolometer material that causes a metal-insulator phase transition at an appropriate temperature. The fact that a bulk sample of this material undergoes a metal-insulator phase transition at about 360 K has been reported by CS Alexander et al., Phys.
Rev. B, 60 , p. 8422 (1999). G. Cao, et al., Phys. Rev. B, 6 shows that _TMI and resistivity decrease by partially substituting La or Sr for Ca in this substance.
1 , p. 5053 (2000).

Although La is not used much in the Si process, Ca is highly compatible with the Si process because it has similar properties to Sr already used in the Si process. Ru and SrRuO ₃ are already used as electrode materials in the Si process. Therefore, Ca _2-x Sr _x RuO ₄ has high compatibility with the Si process. However, the bulk metal-insulator transition of these materials is very steep and the TCR at the phase transition temperature
Is too high and the temperature range where the TCR is 4% or more is narrow, making it difficult to use for infrared image sensors.

In the present invention, a structure suitable for an infrared image sensor could be obtained by epitaxially growing the above-mentioned substance on an optimal underlayer. The inventors have found that the optimum composition for the bolometer material is Ca _2-x Sr _x RuO _4-d (where 0 ≦ x ≦ 0.05). T _MI in the case epitaxial distortion effects of this substance is not present, is expressed as T _MI = -1940x + 371.

[0067] To satisfy about 300 K or more necessary as T _MI, Sr content x is required to be about 0.037 or less. Further, in order to satisfy the desired _TMI of about 350 K or more, the Sr content x is desirably 0.011 or less. In the present invention, since it is possible to slightly raise the T _MI by the effect of epitaxial strain, it is desirable that x is about 0.05 or less. Since this T _MI of the substance is not very high, there is a need to be careful so as not to decrease T _MI by epitaxial strain.

As a result of an experiment in which thin films of this material were deposited on various substrates and underlayers, the optimum underlayer material was NdGa.
O ₃ , PrGaO ₃ , LaGaO ₃ , Sr ₂ AlTaO ₆ , and SrTiO ₃ were found. These have a lattice mismatch with Ca ₂ RuO ₄ of about 1.4.
% Or less, and the and to not lower than the bulk value T _MI of Ca ₂ RuO _4, is larger average lattice constant than towards the underlayer Ca ₂ RuO _4. When the lattice constant of the underlayer is larger, the insulating phase is stabilized and _TMI is slightly increased. Further, since this substance has a layered crystal structure, when a thin film is formed, it is easily oriented parallel to the substrate surface. In the following, the orientation shown in FIG. 5 is considered with the c-axis being the direction perpendicular to the layer among the crystal axes.

The most suitable electrode layer material is CaRuO ₃ , Ca ₃ R
u ₂ O ₇ , La _0.5 Sr _0.5 CoO ₃ , Ir, LaNiO ₃ , NiSi ₂ , Rh, CoSi ₂
And LaN. They, Ca ₂ RuO ₄ and is a lattice mismatch than about 2.5%, and Ca ₂ to RuO ₄ of T _MI lowered than the bulk value to stabilize the metal phase, towards the electrode layer is Ca ₂ The lattice constant is smaller than that of RuO ₄ .

A second suitable bolometer material is RNiO _3-d . Here, R is a rare earth element or a mixture of a plurality of rare earth elements, and d is a value representing a deviation of oxygen from stoichiometry.

R preferably has an average ion radius of about 0.125 nm or less and about 0.121 nm or more when it becomes a trivalent ion. When the ion radius is in this range, the metal-
Insulator phase transition occurs and _TMI shows a value of about 300 K or more. In RNiO _3-d , R has a 12-coordinate, and the above ionic radius is a value in the case of 12-coordination. The ion radius is RD Shannon, Acta Cryst. A32 , p.751 (1976)
In a list. The ionic radius of the 12-coordinate Sm ³⁺ is about 0.124 nm. When the value of 12 coordination is not described, the value of 9 coordination can be used as a guide, and the average ionic radius of 9 coordination is preferably about 0.1145 nm or less and about 0.1100 nm or more. The ionic radius of the 9-coordinate Eu ³⁺ is about
0.112 nm. Therefore, SmNiO _3-d or EuNiO _3-d is a substance satisfying the condition of the ionic radius. Also, by mixing two kinds of rare earth elements, Sm _1-x Pr _x NiO _3-d (0
<X ≦ 0.2).

Among the above substances, SmNiO _3-d is most preferable from the viewpoint that the composition of the thin film is easy to control because the number of elements is small and the process cost is low. JB Torrance et al., Phys. Rev. B, 45 , p. 82 shows that a bulk sample of SmNiO _3-d undergoes a metal-insulator phase transition at about 403K.
09 (1992). However, this substance in a bulk state cannot be used for an infrared image sensor because the metal-insulator phase transition is too steep and the TCR is small near room temperature. In the present invention, a material suitable for an infrared image sensor can be obtained by epitaxial growth on an optimal underlayer.

[0073] Since the T _MI in the bulk material is about 403K and too high, it is desirable to select a base layer such that the T _MI is lowered slightly by epitaxial strain. The optimal underlayer materials are LaAlO ₃ , PrSrGaO ₄ , CeO ₂ , LaSrGaO ₄ , NdGaO ₃ , Pr
GaO ₃ , LaGaO ₃ , Sr ₂ AlTaO ₆ , Ca _1-x Sr _x TiO ₃ (where 0 ≦
x ≦ 1). They are less about 2.4% lattice mismatch with the SmNiO _3, and the T _MI of SmNiO ₃ to lower slightly than the bulk value, towards the underlying layer has a larger lattice constant than SmNiO _3.

The most suitable electrode layer material is Pd, Sr ₃ Ru
_{2 O 7, Sr 2 RuO 4} , CaRuO 3, Ca 3 Ru 2 O 7, La 0 .5 Sr 0.5 CoO 3, I
r, LaNiO ₃ and NiSi ₂ were found. These are Sm
Lattice mismatch with NiO ₃ is about 2.1% or less and SmNiO ₃
To stabilize the metal phase is lowered than the bulk value T _MI, towards the electrode layer has a larger lattice constant than SmNiO _3.

In this substance system, the TCR can also be adjusted by element substitution. Ni site, Al, Fe, C
By substituting about 0 to 5% with o, Cr, Ga, Mn, etc., the metal-insulator phase transition can be moderated. Further, in the substitution of substituted and Ni sites of the rare earth element, it is possible to adjust the T _MI. The following two substances are suitable for elemental substitution.

In the first example, Sm _1-x Nd _x Ni _1-y B _y O ₃ (B = Al, F
e, Co, Cr, Ga, Mn). In this case, T _MI when there is no effect of epitaxial strain is expressed T _MI = a (403-202x) (1-10y). To meet the above 350K of desired value as T _MI is preferably Nd content x is about 0.26 or less.

In the second example, Eu _1-x Nd _x Ni _1-y B _y O ₃ (B = Al, F
e, Co, Cr, Ga, Mn). In this case, T _MI when there is no effect of epitaxial strain is expressed T _MI = a (461-260x) (1-10y). To meet the above 350 K the desired value as T _MI is preferably Nd content x is about 0.43 or less.

A third suitable material for the bolometer material is RBaCo ₂ O _{5 + d} . Here, R is a rare earth element or a mixture of a plurality of rare earth elements, and d is a positive number representing non-stoichiometry of oxygen.

[0079] To satisfy above 300 K of the required value as T _MI, average ionic radius when it becomes trivalent ions of R is about 0.1
It is desirable that the thickness be 08 nm or more. 0.108 n ion radius
Below m, the _TMI is too low. In RBaCo ₂ O _{5 + d} , R is in 9 to 10 coordination, and thus the above ionic radius is a value in the case of 9 coordination. The ionic radius of the 9-coordinate Tb ³⁺ is about 0.1095 nm. Therefore, TbBaCo ₂ O _{5 + d} satisfies the condition of ionic radius. In addition, as R, Pr, N
d, Sm, Eu, Gd, Dy can be used. Further, Eu _1-x Gd _x BaCo ₂ O _{5 + d} (0 <x <1) may be used by mixing two rare earth elements.

The fact that bulk polycrystals of this group undergo a metal-insulator phase transition has been described by A. Maignan et al., J. Soli
d State Chem. 45 , p. 247 (1999).
However, in the bulk state, the metal-insulator phase transition is too steep and the temperature range where the TCR is 4% or more is narrow, so that it cannot be used for an infrared image sensor. In the present invention, a material suitable for an infrared image sensor can be obtained by epitaxial growth on an optimal underlayer.

Here, since this substance has a layered crystal structure, when a thin film is formed, it is easily oriented parallel to the substrate surface. In the following, of the crystal axes, the direction perpendicular to the layer is c
As an axis, consider the orientation shown in FIG. This T _MI in the bulk substance group is not very high, it is necessary to be careful not to decrease T _MI by epitaxial strain.

The optimal underlayer materials are LaAlO ₃ , PrSrGaO ₄ ,
CeO ₂ , LaSrGaO ₄ , NdGaO ₃ , PrGaO ₃ , LaGaO ₃ , Sr ₂ AlTaO ₆ ,
It was found that Ca _1-x Sr _x TiO ₃ (where 0 ≦ x ≦ 1.0). These have a lattice mismatch with RBaCo ₂ O _{5 + d} of about 2.6% or less. Further, RBaCo ₂ O _{5 + d,} the difference between a _b and b _b is increased at high temperature metallic phase in comparison to the low temperature of the insulator phase. This difference is expressed by _{orthorhombicity = (b b -a b)} / (b b + a b) an amount of. Typically, in the low temperature insulator phase, orthohorho
mbicity is about 0.005, and in the hot metal phase, it is orthorhomb
icity is about 0.011. Above the base layer material are approximately equal a _s and _{b s, orthorhombicity = (b s} -a s) / (b s + a s) is about
Since it is 0.007 or less to stabilize the insulating phase by epitaxial strain serves to not lower than the bulk value T _MI.

The most suitable electrode layer material is Pd, Sr ₃ Ru
_{2 O 7, Sr 2 RuO 4} , CaRuO 3, Ca 3 Ru 2 O 7, La 0 .5 Sr 0.5 CoO 3, I
r, LaNiO ₃ , NiSi ₂ , Rh, and CoSi ₂ . These are substances whose lattice mismatch with RBaCo ₂ O _{5 + d} is about 2.3% or less and whose contact resistance is low as a result of the experiment. In this material system, the TCR can also be adjusted by elemental substitution. By replacing the Co site with Ga by about 0 to 10%, the metal-insulator phase transition can be moderated. It is also possible to partially replace Ba in this substance system with Sr.

Hereinafter, a specific example of this embodiment will be described.

(Example 1) An example in which a Ca ₂ RuO ₄ thin film is produced by an RF sputtering method will be described. RF power of 70 using a 4 inch diameter Ca ₂ RuO ₄ sintered target
W. The sputtering gas was a mixed gas of Ar 90% + O ₂ 10%, and the film was formed at a total pressure of 2 Pa. The substrate temperature was 600 ° C.

A SrTiO ₃ (100) surface was used as a substrate, and a Ca ₂ RuO ₄ thin film of about 100 nm was deposited thereon, considering this as an underlayer.
As a result of X-ray diffraction, it was confirmed that a Ca ₂ RuO ₄ epitaxial thin film having c-axis orientation was formed.

FIG. 6 shows the temperature dependence of the resistance in the in-plane direction. The horizontal axis is temperature, and the vertical axis is resistivity. About 300-350 K
4% <TCR <9% was obtained over the entire region, and good characteristics were obtained as a bolometer thin film.

(Example 2) In the same manner as in Example 1, Ca ₂ RuO ₄ thin films were deposited on various underlayers,
Was measured for TCR. FIG. 9 shows the result.

[0089] underlayer lattice constant of 9, shows the average of a _b, b _b matched to the direction of the lattice constant a _s, bulk value of b _s. a _b and b _b are in the direction of the primitive unit cell of perovskite. Therefore, there are cases where a _s and b _s are different from the original unit cell of the underlayer material. FIG.
From TCR value, the absolute value of the mean lattice mismatch LM _AV ⁱ is about 1.4
% Was found to be desirable.

[0090] (Example 3) The same procedure as in Example 1, depositing a Ca ₂ RuO ₄ thin film on the various electrode layers, the temperature dependence of the resistance was measured and estimated T _MI. Then, T _MI was examined whether lowered or elevated compared to the bulk values. The results are shown in FIG.

The LM shown in FIG._AV ^mIs the metal of the bolometer substance
It is obtained using the lattice constant of the phase. Result of FIG.
The average lattice mismatch LM_AV ^mIs less than about 2.5%
Is desirable. If the lattice mismatch is larger than this,
The crystallinity of the bolometer thin film decreases and the resistivity increases.
T_MIThat the metal phase, which is the high-temperature phase,
Means that the contact resistance is reduced.
Can be. From the results of FIG. 10, the optimal electrode layer material is
Ca_ThreeRu_TwoO₇, La_0.5Sr_0.5CoO_Three, Ir, LaNiO_Three, NiSi _Two, Rh, C
oSi_2, LaN.

(Example 4) A SmNiO ₃ thin film was prepared by a molecular beam epitaxy (MBE) method. FIG. 7 shows a schematic diagram of a molecular beam epitaxy apparatus.

As shown in FIG. 7, the vacuum vessel 21 is evacuated by a cryopump. A substrate holder 22 is provided in the vacuum container 21, and a substrate 23 is set on the substrate holder 22, and the substrate holder 22 is heated by a heater 24. A plurality of Knudsen cells 25 are provided so as to face the substrate 23, and each Knudsen cell 25 is provided.
A cell shutter 26 is provided in the opening of the. Each Knudsen cell 25 is filled with each metal of Sm, Ni, Ce, Sr, Ti, and Nd, which are constituent elements of a thin film formed in the following examples. Further, in order to cause an oxidation reaction necessary for obtaining an oxide thin film, a pure ozone gas generated by an ozone generator 27 is ejected from a nozzle 28 to irradiate the substrate 23.

In order to produce a SmNiO ₃ thin film, it is necessary to produce Ni ^3+, which requires strong oxidizing conditions. In this embodiment, pure ozone gas having a very strong oxidizing power is used, and 700 ° C.
Oxidation at a relatively low temperature of 300 ° C or higher
Successfully made ³⁺ .

In the present embodiment, the flux of the ozone gas irradiated on the substrate during the deposition of the SmNiO ₃ single phase thin film was about 9.5 × 10 ^−6.
mol · sec ^-1 · m ^-2 . The substrate temperature during film formation is about 700 ° C. Even during the process of cooling to about 200 ° C. after the film formation, irradiation with ozone gas was continued to sufficiently oxidize. As a result of X-ray diffraction, it was confirmed that an SmNiO ₃ single-phase thin film grown epitaxially was formed.

A CeO ₂ film was deposited on the underlayer by MBE. CeO ₂
During deposition of the underlayer, the ozone flux is about 1.5 × 10 ^-7 mol · s
The substrate temperature is about 700 ° C. at ec ⁻¹ · m ⁻² . Under these conditions, Ce
O ₂ grows with good crystallinity and flatness.

The SrTiO ₃ (100) surface was used as the substrate, and the underlayer was made of Ce.
An O ₂ (100) oriented film was deposited at about 100 nm, and a SmNiO _3-d thin film was deposited thereon at about 100 nm. FIG. 8 shows the temperature dependence of the resistance. The horizontal axis is temperature, and the vertical axis is resistivity. 4% <TCR <9% was obtained over the entire range of 300 to 350 K, and good characteristics were obtained as a bolometer thin film.

[0098] In addition to the ozone gas used in the present embodiment, there is also a method of generating oxygen plasma by electron cyclotron resonance and performing oxidation using the oxygen plasma. In the molecular beam epitaxy method in this embodiment, the Knudsen cell is used as a source element supply source, but an evaporation source heated by an electron gun can be used as a molecular beam supply unit. Also, a thin film can be grown by a method of supplying an organic metal molecular beam from a Knudsen cell or a gas source nozzle. In this embodiment, the thin film is manufactured by the molecular beam epitaxy method. However, the thin film can be manufactured by a sputtering method, a laser ablation method, a chemical vapor deposition (CVD) method, or the like.

In the above-described manner, SmNiO ₃ was deposited on various underlayers.
Thin films were deposited and their TCR at 300-350 K was measured. The result is shown in FIG.

From the TCR values in FIG. 11, the average lattice mismatch LM
It was found that the absolute value of _AV ⁱ was desirably 2.4% or less.

Further, in the same manner, Sm is formed on various electrode layers.
NiO ₃ thin films were deposited, the temperature dependence of the resistance was measured, and the _TMI was estimated. Then, it was investigated whether T _MI is lowered or elevated compared to the bulk values. FIG. 12 shows the result.

If the lattice mismatch is large, the resistance of the bolometer film
The rate will increase. Average lattice mismatch LM_AV ^mIs the absolute value of
It was found that it was desirable to be 2.1% or less. T_MIBut
Down means that the metal phase has stabilized
As a result, the contact resistance can be reduced. Is it the result of FIG.
The optimal electrode layer material is Pd, Sr_ThreeRu_TwoO₇, Sr_TwoRuO_Four, CaR
uO _Three, Ca_ThreeRu_TwoO₇, La_0.5Sr_0.5CoO_Three, Ir, LaNiO_Three, NiSi_Twoso
I found something.

(Example 5) A TbBaCo ₂ O _{5 + z} thin film was produced by an RF sputtering method. 4 inch diameter TbBaCo
RF power was set to 100 W using a ₂ O _{5 + z} sintered target. Sputtering gas is Ar50% + O ₂ 50% gas mixture,
The film was formed at a total pressure of 2 Pa. The substrate temperature was about 600 ° C. The substrate, that is, the SrTiO ₃ (100) plane was used for the underlayer.

As a result of X-ray diffraction, cb-axis oriented TbBaCo ₂ O
It was confirmed that a _{5 + z} epitaxial thin film was formed. As a result of measuring the temperature dependence of the resistance, a TCR of about 3 to 6% was obtained in a temperature range of 300 to 350 K.

In the above-described manner, TbBaCo
_{A 2} O _{5 + z} thin film was deposited and its TCR at 300-350K was measured. The result is shown in FIG. In the same manner, TbBaCo ₂ O _{5 + z} thin films were deposited on various electrode layers, and their contact resistances were estimated. The result is shown in FIG.

LaAlO ₃ , PrSrGaO ₄ , CeO ₂ , LaSrGaO ₄ , NdGa
O ₃ , PrGaO ₃ , LaGaO ₃ , Sr ₂ AlTaO ₆ , and Ca _1-x Sr _x TiO ₃ (where 0 ≦ x ≦ 1.0) were found to be optimal as the underlayer. Further, Pd, Sr ₃ Ru ₂ O ₇ , Sr ₂ RuO ₄ , CaRuO ₃ , Ca ₃ Ru ₂ O
₇ , La _0.5 Sr _0.5 CoO ₃ , Ir, LaNiO ₃ , NiSi ₂ , Rh, and CoSi ₂
It was found that the contact resistance was small when was used, and that it was optimal as an electrode layer.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the gist thereof. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed constituent elements. For example, even if some constituent elements are deleted from the disclosed constituent elements, they can be extracted as an invention as long as a predetermined effect can be obtained.

[0108]

According to the present invention, a thermal infrared detecting device having an appropriate temperature characteristic at a temperature equal to or higher than room temperature is obtained by using an appropriate substance for the bolometer thin film and forming the bolometer thin film epitaxially with distortion. An element can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of a thermal infrared detecting element according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a main part of the thermal infrared detection element shown in FIG.

FIG. 3 is a cross-sectional view showing a configuration of a main part of another example of the thermal infrared detection element according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a main part of still another example of the thermal infrared detection element according to the embodiment of the present invention.

FIG. 5 is a diagram for explaining lattice matching between an underlayer and a bolometer thin film according to the embodiment of the present invention.

FIG. 6 is a diagram showing an example of the temperature dependence of the resistance of the bolometer thin film according to the embodiment of the present invention.

FIG. 7 is a view showing an example of an apparatus for manufacturing a bolometer thin film according to the embodiment of the present invention.

FIG. 8 is a view showing another example of the temperature dependence of the resistance of the bolometer thin film according to the embodiment of the present invention.

FIG. 9 is a diagram showing suitability of various underlayers according to the embodiment of the present invention.

FIG. 10 is a view showing characteristics of various electrode layers according to the embodiment of the present invention.

FIG. 11 is a view showing characteristics of various underlayers according to the embodiment of the present invention.

FIG. 12 is a view showing characteristics of various electrode layers according to the embodiment of the present invention.

FIG. 13 is a view showing characteristics of various underlayers according to the embodiment of the present invention.

FIG. 14 is a view showing characteristics of various electrode layers according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 2 ... Micro bridge structure 3 ... Void 4 ... Foot 5 ... Metal wiring 6 ... Base substrate 7 ... Conductive electrode layer 8 ... Insulating base layer 9 ... Bolometer thin film 11 ... Embedded oxide film 12 ... Passivation film 13 ... Buffer layer 14 ... Single-crystal silicon layer 21 ... Vacuum container 22 ... Substrate holder 23 ... Substrate 24 ... Heater 25 ... Knudsen cell 26 ... Cell shutter 27 ... Ozone generator 28 ... Nozzle 31 ... Crystal lattice of base layer 32 ... Bolometer material Crystal lattice

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 27/14 H01L 27/14 K F term (Reference) 2G065 AB02 BA12 BA14 BA32 BA34 BE08 CA13 DA18 DA20 2G066 BA09 BA55 BB09 CA02 4M118 AA10 AB10 BA01 CA01 CB20

Claims (9)

[Claims] 1. A thermal infrared detecting element comprising an insulating base layer having a crystal structure and a bolometer thin film epitaxially formed on the base layer, wherein the bolometer thin film has a chemical formula of Ca _{2− x} Sr _x RuO
_4-d (where 0 ≦ x ≦ 0.05, d is a value representing a deviation of oxygen from stoichiometry), and has a lattice constant different from that of the underlayer. Thermal infrared detector. About wherein said base layer and two crystal axis parallel to the interface between the bolometer thin film, the underlying layer lattice constants a _s and b _s in the bulk state of the lattice constant in the bulk state of the bolometer thin film when a a _b and _{b b, (a s + b} s) is (a _b + b _b) thermal type infrared sensing device according to claim 1, wherein greater than. 3. The bolometer thin film is further epitaxially formed on a conductive electrode layer having a crystal structure, and the two crystal axes parallel to an interface between the electrode layer and the bolometer thin film are formed on the electrode. when the lattice constant in the bulk state of the layers a _e and b _e, the lattice constant in the bulk state of the bolometer thin film was a _b and b _b, (a _e +
b _e) is (a _b + _{b b)} thermal type infrared sensing device according to claim 1 or 2, characterized in smaller than. 4. A thermal infrared detecting element comprising an insulating base layer having a crystal structure and a bolometer thin film epitaxially formed on the base layer, wherein the bolometer thin film has a chemical formula of RNiO _{3−. d} (where R is a single or a plurality of rare earth elements and the average ion radius when converted into a trivalent ion is 0.121 nm or more and 0.125 n
m, d is a value represented by the following formula: d is a value representing a deviation of oxygen from stoichiometry), and has a lattice constant different from that of the underlayer. 5. A lattice constant as a _s and b _s in a bulk state of the underlayer and a lattice constant in a bulk state of the bolometer thin film for two crystal axes parallel to an interface between the underlayer and the bolometer thin film. when a a _b and _{b b, (a s + b} s) is (a _b + b _b) thermal type infrared sensing device according to claim 4, wherein greater than. 6. The bolometer thin film is further epitaxially formed on a conductive electrode layer having a crystal structure. The bolometer thin film has two crystal axes parallel to an interface between the electrode layer and the bolometer thin film. when the lattice constant in the bulk state of the layers a _e and b _e, the lattice constant in the bulk state of the bolometer thin film was a _b and b _b, (a _e +
b _e) is (a _b + _{b b)} thermal type infrared sensing device according to claim 4 or 5, wherein greater than. 7. A thermal infrared detecting element comprising an insulating base layer having a crystal structure and a bolometer thin film epitaxially formed on the base layer, wherein the bolometer thin film has a chemical formula of RBaCo ₂ O. _{5 + d} (where R is a single or a plurality of rare earth elements and the average ionic radius when converted to a trivalent ion is 0.108 nm or more, d
Is a value represented by the following formula: (a value representing the deviation of oxygen from stoichiometry) and a lattice constant different from that of the underlayer. About wherein said undercoat layer and the crystal axis of the two parallel to the interface between the bolometer thin film, the underlying layer lattice constants a _s and b _s in the bulk state of the lattice constant in the bulk state of the bolometer thin film when a a _b and _{b b, 0.974 ≦ (a s} + b s) / (a b + b b) thermal type infrared sensing device according to claim 7, characterized in that a ≦ 1.005. 9. The bolometer thin film is further epitaxially formed on a conductive electrode layer having a crystal structure. The bolometer thin film has two crystal axes parallel to an interface between the electrode layer and the bolometer thin film. when the lattice constant in the bulk state of the layer was a _e and b _e, the lattice constant in the bulk state of the bolometer thin film and a _b and _{b b, 0.977 ≦ (a e} + b e) / (a b + a b) The thermal infrared detecting element according to claim 7 or 8, wherein ≤ 1.001.