JP2000356546A - Infrared detecting element and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a small and high-performance infrared detecting element. SOLUTION: In manufacturing an infrared detecting element having a resistance change type first infrared detection unit and a pyroelectric or dielectric constant change type second infrared detection unit on the same surface of a substrate, a first infrared detection unit is provided. The same material is used for the resistor and one electrode of the second infrared detecting section, and these are formed simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detecting element for detecting a thermal element such as a human body and simultaneously measuring its temperature.

[0002]

2. Description of the Related Art In recent years, a technology for detecting infrared rays emitted from a heat body such as a human body has been applied to means for monitoring crime prevention, traffic, disasters and the like, and temperature measuring means. By using the infrared detecting element, for example, the temperature of the heat body can be measured in a non-contact manner.

[0003] Infrared detecting elements are roughly classified into quantum elements utilizing the photoelectric effect and thermal elements utilizing infrared heat. Among them, the thermal element has attracted widespread attention because it has lower sensitivity than the quantum element but does not depend on the wavelength of infrared rays and does not require cooling. Thermal elements are further classified into pyroelectric elements, variable resistance elements (bolometer type), thermocouple elements, variable dielectric constant elements (so-called dielectric bolometer elements), and the like, depending on their operation principles.

[0004] Pyroelectric elements are widely used for detecting human bodies because of their high sensitivity. The resistance change type and the dielectric constant change type are used for temperature measurement because the absolute value of the temperature can be obtained. In recent years, an ear canal thermometer using a thermal element has been proposed. This thermometer can measure body temperature in a short time by inserting the sensor unit into the ear canal. The sensor unit of the thermometer detects infrared rays from the human body by the pyroelectric effect. The sensor unit detects the temperature difference between the temperature of the piezoelectric chopper and the temperature in the ear canal, and further detects the temperature of the piezoelectric chopper by a contact thermistor. The body temperature of the subject is calculated from the temperature of the piezoelectric chopper and the temperature difference therefrom.

In an actual temperature detecting system, a plurality of different infrared detecting elements may be used in combination in order to obtain a desired function. For example, two types of detection units are provided in the system, an infrared detection unit for detecting a heating element and another infrared detection unit for measuring the temperature of the heating element. Either a pyroelectric element that uses a normal pyroelectric effect or a type that uses an electric field-induced pyroelectric effect among dielectric constant change types is used as a detecting unit for detecting a thermal body. A resistance change type or dielectric constant change type element is used for the detection unit for measurement.

[0006]

If such different types of detectors are formed on the same substrate, the subsequent assembling process can be simplified and the size of the element can be reduced. However, if these detecting portions are separately formed on the substrate, components in the components may be diffused or deteriorated due to a thermal load during the formation, and an element having desired characteristics may not be obtained. is there. In addition, since it is necessary to separately provide a signal detection wiring for each of the formed detection units, there is a limit to miniaturization of the element.

An object of the present invention is to solve the above problems and to provide a small and high-performance infrared detecting element.
It is another object of the present invention to provide a method of manufacturing an infrared detecting element capable of manufacturing such an infrared detecting element simply and with a high yield.

[0008]

According to the present invention, there is provided a method of manufacturing an infrared detecting element including a first infrared detecting section of a resistance change type and a second infrared detecting section of a pyroelectric or dielectric constant type on the same surface of a substrate. The same material is used for the resistor of the first infrared detector and one electrode of the second infrared detector, and these are formed simultaneously.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An infrared detecting element of the present invention comprises a substrate, a first infrared detecting section of a resistance change type formed on the same surface of the substrate, and a second infrared detection section of a pyroelectric or dielectric constant type. And a resistor of the first infrared detecting section and one electrode of the second infrared detecting section are made of the same conductive material.

For example, after forming a conductive film on a substrate, this film is processed to form a resistor and an electrode. This method is particularly useful for forming an electrode (hereinafter, referred to as a lower electrode) on a side sandwiched between a substrate and a pyroelectric film or a dielectric film. Further, a conductive film having a desired shape is formed as each of the resistor and the electrode by a sputtering method using a metal mask or the like. This method is particularly useful for forming an electrode (hereinafter referred to as an upper electrode) having one surface bonded to a pyroelectric film or a dielectric film and the other surface being opened. Furthermore, by simultaneously forming the wiring patterns to these infrared detection units, integration with the signal processing unit in a later process is facilitated, and the size and cost of the device can be reduced.

[0011] The substrate is preferably made of MgO single crystal. In addition, a substrate (for example, a crystallized glass substrate) formed by stacking oxide films having a rock salt type crystal structure such as MgO, NiO, or CoO, or a single crystal substrate of a semiconductor such as Si can be used. In addition, also when using a Si substrate, it is desired to provide a buffer layer made of a rock salt type crystal structure oxide such as MgO, NiO, or CoO. When an Si substrate is used, the above-described gap layer can be easily formed directly below each detection unit by an established micromachining technique.

The resistor of the resistance change type infrared detecting section (first infrared detecting section) is preferably Ni, Ti, Pt, Au,
It is made of vanadium oxide or polycrystalline silicon. In particular, an element with high sensitivity can be obtained by using vanadium oxide or polycrystalline silicon. The pyroelectric film of the pyroelectric infrared detector is preferably made of a lead-based ferroelectric. In addition, a bismuth-based ferroelectric such as SrBi ₂ Ta ₂ O ₉ can be used. The dielectric film of the dielectric constant change type infrared detector is preferably a lead lanthanum titanate (PLT) -based dielectric or barium strontium titanate (BS).
T) -based dielectric. Pt, Pd, I
r, Au, RuO ₂ or (La, Sr) CoO ₃ can be used.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 In this embodiment, an infrared detecting element provided with a resistance change type infrared detecting unit and a pyroelectric type infrared detecting unit will be described as an example. Infrared detecting element 10 of the present embodiment
0 is shown in FIG. On the upper surface of a substrate 101 made of MgO single crystal, a pyroelectric detector 110 and a resistance change detector 1
20 are arranged. The substrate 101 is obtained by cleaving an MgO single crystal on a (100) plane and mirror-polishing the surface. The pyroelectric detector 110 includes a lower electrode film 102 made of Pt, which is sequentially laminated on a substrate 101, and a composition of Pb.
Pyroelectric film 10 composed of _0.9 La _0.1 Ti _0.975 O ₃ PLT
3 and an upper electrode 104 made of a Ni film. On the other hand, the resistance change detection unit 120 includes a thermal insulating film 105 and a resistor film 108 which are sequentially stacked on the substrate 101. Thermal insulating film 105 is made of, for example, polyimide.

A gap 107 is formed between the bottom of each of the detectors 110 and 120 and the substrate 101, and the detectors 110 and 120 are fixed to the thermal insulating film 105 at their peripheral edges. , Are held by the substrate 101. By providing the gap 107, heat transfer between the detection units 110 and 120 and the substrate 101 is suppressed, and the detection units 110 and 120 can obtain high sensitivity. Forming a thermal insulating layer 105 of polyimide or the like around the detection units 110 and 120 suppresses heat transfer between the detection units 110 and 120 and the substrate 101, and forms the void 107 in the substrate 101. Therefore, it is possible to suppress a decrease in mechanical strength of the element 100 due to the above, and to prevent the element 100 from being deformed or damaged. In the present embodiment, the upper electrode 104 of the pyroelectric detection unit 110 and the resistance change detection unit 120
Are formed of the same material, and these are formed simultaneously.

Hereinafter, a specific example of a method of manufacturing the infrared detecting element 100 will be described with reference to FIG.

First, a Pt film 102a having a thickness of 250 nm is formed on a substrate 101 made of MgO single crystal by an RF magnetron butter method (FIG. 2A). Where P
The t film 102a is formed such that its film growth direction is oriented to the (100) plane. The formation of the Pt film 102a is performed, for example, under the following conditions.

[0018]

[Table 1]

Next, as shown in FIG. 2B, a pyroelectric film 103a made of PLT having a thickness of 3 μm is formed on the formed Pt film 102a by RF magnetron sputtering.
To form The pyroelectric film 103a is formed, for example, under the following conditions.

[0020]

[Table 2]

Next, as shown in FIG. 2C, the pyroelectric film 103a is processed into a desired shape. First, the pyroelectric film 10
After applying a photoresist to the surface of 3a by spin coating, the photoresist is processed into a desired shape by photolithography. Next, the portion of the pyroelectric film 103a exposed from the resist is removed by wet etching using hydrofluoric nitric acid to form the pyroelectric film 103 for the pyroelectric detector 110. After that, the photoresist remaining on the pyroelectric film 103 is removed.

Next, as shown in FIG. 2D, the exposed Pt film 102a is processed into a desired shape. That is,
Etching hole 106 for forming void 107
And an exposed portion 10 for forming the detecting portion 120 thereon.
9 is formed, and the lower electrode 102 of the detection unit 110 is obtained. Note that a wiring pattern to the signal processing unit is also formed at the same time. First, a photoresist is applied on the surface on the side of the Pt film 102a by spin coating, and then processed by photolithography into a shape similar to that of the lower electrode 102 from which the resist is to be obtained. Next, a portion of the Pt film 102a exposed from the resist is removed by sputter etching using an Ar gas, and the substrate 101 at that portion is exposed. After that, the resist is removed.

Next, as shown in FIG. 2E, a thermal insulating film 105 is formed on the upper surface of the substrate 101 so as to cover the peripheral portion of the patterned pyroelectric film 103. For example, after applying a photosensitive polyimide (for example, “Photo Nice” of Toray Industries, Inc.) by spin coating, this is processed into a desired shape by photolithography and has a thickness of 2 μm.
Is formed.

Next, as shown in FIG. 2F, the upper electrode 10 is formed on the exposed upper surface of the pyroelectric film 103 and on the upper surface of the thermal insulating film 105 formed on the exposed portion 109, respectively.
4 and the resistor film 108 are formed. For example, metal N
A nickel film having a thickness of 20 nm is formed at a rate of 4 nm / min at room temperature under a pressure of 5 × 10 ⁻⁴ Pa by an electron beam evaporation method using i as a target. After a resist is applied to the upper surface of the formed nickel film and processed into a desired shape by photolithography, the nickel film is processed into the upper electrode 104 and the resistor film 108 by wet etching using a cerium nitrate-based etchant.

Finally, an etchant (for example, phosphoric acid at 80 ° C.) is injected into the etching hole 106, and a portion of the substrate 101 immediately below the pyroelectric film 103 and the resistor film 108 is formed.
The infrared detecting element 1 shown in FIG.
00 is obtained.

As described above, the upper electrode 104 of the pyroelectric detector 110 and the resistance film 1 of the resistance change detector 120
08 are formed at the same time, an infrared detecting element having excellent characteristics can be obtained.

<Embodiment 2> In this embodiment, another preferred example of an infrared detecting element having a pyroelectric detector and a resistance change detector as in the first embodiment will be described. FIG. 3 shows an infrared detecting element of this embodiment. This infrared detecting element 20
0 includes a pyroelectric detection unit 210 and a resistance change detection unit 220 as in the infrared detection element 100 of the first embodiment. However, the lower electrode of the pyroelectric detector 210 and the resistor film 208 of the resistance change detector 220 are made of the same material.

First, the same Mg as used in Example 1 was used.
As shown in FIG. 4A, a 200-nm-thick substrate was formed on an O-single-crystal substrate 201 by RF magnetron sputtering.
An m-th Pt film 202a is formed. Further, as shown in FIG. 4B, a pyroelectric film 203a made of PLT having a thickness of 3 μm is formed on the formed Pt film 202a by the RF magnetron sutter method. The obtained pyroelectric film 203a is processed to form a pyroelectric film 203 for the pyroelectric detection unit 210 as shown in FIG.

Next, as shown in FIG. 4D, the exposed Pt film 202a is processed into a desired shape. That is,
Etching hole 20 for forming void 207
6. The lower electrode 202 of the pyroelectric detector 210 and the resistor film 208 of the resistance change detector 220 are formed. Next, as shown in FIG. 4E, a thermal insulating film 205 is formed so as to cover the peripheral portion of the pyroelectric film 203 on the substrate 201 and the resistor film 208. Next, as shown in FIG. 4F, the upper electrode 204 is formed on the exposed upper surface of the pyroelectric film 203.
Is formed by, for example, an electron beam evaporation method. Finally, an etchant (for example, phosphoric acid heated to 80 ° C.) or the like is injected into the etching hole 206, and a portion of the substrate 201 immediately below the pyroelectric film 203 and the resistor film 208 is etched, as shown in FIG. Forming a void portion 207,
The infrared detecting element 200 is obtained.

<< Embodiment 3 >> The infrared detecting element 3 of this embodiment
00 is shown in FIG. The infrared detecting element 300 includes two types of detecting units, a permittivity changing type detecting unit 310 and a resistance changing type detecting unit 320. The substrate 301 is made of the same MgO single crystal as that used in the first embodiment. The permittivity change detecting unit 310 includes a lower electrode 302 made of a Pt film sequentially laminated on a substrate 301 and a composition of Ba _0.65 Sr _0.35 TiO 2.
_3, a dielectric film 303 made of barium strontium titanate (hereinafter referred to as BST) and an upper electrode 304 made of a Ni film. On the other hand, the resistance change detection unit 32
0 is a thermal insulating film 305 sequentially laminated on the substrate 301
And a resistor film 304. The thermal insulating film 305 is
For example, it is made of polyimide. Each detector 310 and 3
A gap 307 is formed between the bottom of the substrate 20 and the substrate 301, and the detection units 310 and 320 are held by the substrate 301 at their peripheral edges, respectively. In this embodiment,
The upper electrode 304 of the pyroelectric detector 310 and the resistor film 304 of the resistance change detector 320 are made of the same material and are formed simultaneously.

Hereinafter, a specific example of the method of manufacturing the infrared detecting element 300 will be described with reference to FIG.

First, as shown in FIG.
1 with a thickness of 250 mm by the RF magnetrons butter method.
A Pt film 302a of nm is formed. Here, the Pt film 30
2a is formed such that its film growth direction is oriented to the (100) plane. The formation of the Pt film 302a is performed, for example, under the same conditions as in the first embodiment. Next, as shown in FIG.
On the formed Pt film 302a, a 3 μm-thick dielectric film 303a is formed by an RF magnetron butter method. The formation of the dielectric film 303a is performed, for example, under the following conditions.

[0033]

[Table 3]

Next, as shown in FIG. 6C, the dielectric film 303a is processed into a desired shape. First, the dielectric film 30
After applying a photoresist to the surface of 3a by spin coating, the photoresist is processed into a desired shape by photolithography. Next, the portion of the dielectric film 303a exposed from the resist is removed by wet etching using hydrofluoric nitric acid to form a dielectric film 303 for the dielectric constant change detecting unit 310. After that, the dielectric film 303
The resist remaining on the top is removed.

Next, as shown in FIG.
The exposed portion of 02a is processed into a desired shape. That is,
Etching hole 306 for forming void 307
And the lower electrode 302 of the permittivity change detecting unit 310 and an exposed portion 309 for forming the detecting unit 320 thereon.
To form First, a photoresist is applied on the surface on the side of the Pt film 302a by spin coating, and then the resist is processed into a desired shape by photolithography.
Next, the portion of the Pt film 302a exposed from the resist is removed by sputter etching using Ar gas, and the substrate 301 in that portion is exposed. After that, the resist is removed.

Next, as shown in FIG.
A thermal insulating film 305 is formed so as to cover the peripheral portion of the dielectric film 303 patterned on the upper surface of the first substrate 1. For example, a photosensitive polyimide is applied by spin coating, and further processed into a desired shape by photolithography,
A thermal insulation film 305 having a thickness of 2 μm is formed. Next, FIG.
As shown in (f), the upper electrode 304 and the resistor film 308 are formed on the exposed upper surface of the dielectric film 303 and the upper surface of the thermal insulating film 305 formed on the exposed portion 309, respectively.
Are simultaneously formed, for example, by the electron beam evaporation method as in the first embodiment. Finally, an etchant (for example, phosphoric acid at 80 ° C.) is injected into the etching hole 306, and the substrate 3
A gap 307 is formed immediately below the pyroelectric film 303 and the resistor film 308 of FIG. 1 to obtain the infrared detecting element 300 shown in FIG.

Embodiment 4 In this embodiment, another preferred example of an infrared detecting element having a permittivity change type detection unit and a resistance change type detection unit, similarly to the third embodiment, will be described.

FIG. 7 shows the infrared detecting element of this embodiment.
The infrared detection element 400 includes a dielectric constant change detection unit 410 and a resistance change detection unit 420, like the infrared detection element 300 of the third embodiment. In the infrared detecting element according to the present embodiment, the lower electrode of the permittivity change detecting section 410 and the resistor film 408 of the resistance change detecting section 420 are made of the same material.

First, the same Mg used in Example 1 was used.
On a substrate 401 made of O single crystal, as shown in FIG.
An m m Pt film 402a is formed. Next, as shown in FIG. 8B, a 3 μm-thick PLT dielectric film 403a is formed on the formed Pt film 402a by the RF magnetrons butter method, and this is further formed as shown in FIG. c)
Then, a dielectric film 403a for the dielectric constant change detecting unit 410 is formed by processing into a desired shape as shown in FIG.

Next, as shown in FIG. 8D, the portion of the Pt film 402a exposed by forming the dielectric film 403 is processed into a desired shape. That is, the etching hole 406 for forming the gap 407, the lower electrode 402 a of the dielectric constant detection unit 410, and the resistance change detection unit 4
Twenty resistor films 408 are formed. Next, as shown in FIG. 8E, a thermal insulating film 405 is formed so as to cover the periphery of the dielectric film 403 patterned on the upper surface of the substrate 401 and the resistor film 408. Next, FIG.
As shown in FIG. 7, an upper electrode 404 is formed on the exposed upper surface of the dielectric film 403 by, for example, an electron beam evaporation method. Finally, an etchant (80 ° C. phosphoric acid) is injected into the etching hole 406 to form the dielectric film 40 on the substrate 401.
A gap 407 is formed in the portion immediately below the resistor 3 and the resistor film 408, and the infrared detecting element 400 shown in FIG. 7 is obtained.

[0041]

According to the present invention, a small and compact infrared detecting element can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a structure of an infrared detecting element according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a state of each manufacturing process of the infrared detecting element.

FIG. 3 is a longitudinal sectional view showing a structure of an infrared detecting element according to another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a state of each manufacturing process of the infrared detecting element.

FIG. 5 is a longitudinal sectional view showing a structure of an infrared detecting element according to still another embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing a state of each manufacturing process of the infrared detecting element.

FIG. 7 is a longitudinal sectional view showing the structure of an infrared detecting element according to still another embodiment of the present invention.

FIG. 8 is a longitudinal sectional view showing a state of each manufacturing process of the infrared detecting element.

[Explanation of symbols]

 100, 200, 300, 400 Infrared detecting element 101, 201, 301, 401 Substrate 102, 202, 302, 402 Lower electrode 102a, 202a, 302a, 402a Pt film 103, 103a, 203, 203a Pyroelectric film 104, 204 , 304, 404 Upper electrode 105, 205, 305, 405 Thermal insulating film 106, 206, 306, 406 Etching hole 107, 207, 307, 407 Void 108, 208, 308, 408 Resistor film 109, 309 Exposed part 110, 210 Pyroelectric detector 120, 220, 320, 420 Resistance change detector 303, 303a, 403, 403a Dielectric film 310, 410 Dielectric constant detector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 37/02 H01L 37/02 (72) Inventor Ryoichi Takayama 1006 Odakadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. F term in the company (reference) 2G065 BA12 BA13 BA14 BB37 CA13 DA06 DA20 2G066 AC13 BA01 BA09 BA34 BA51 BA55 CA08 CA15

Claims (6)

[Claims] A first infrared detecting section of a variable resistance type and a second infrared detecting section of a pyroelectric or dielectric constant type formed on the same surface of the substrate, wherein the first infrared ray is provided. An infrared detecting element, wherein the resistor of the detecting unit and one electrode of the second infrared detecting unit are made of the same conductive material. 2. The infrared detecting element according to claim 1, wherein said resistor and said one electrode are formed simultaneously. 3. The infrared detecting element according to claim 1, further comprising a gap immediately below the first or second detecting portion of the substrate. 4. An infrared detecting element comprising: a substrate; a resistance-change type first infrared detection unit and a pyroelectric or dielectric constant-change type second infrared detection unit formed on the same surface of the substrate. A method for manufacturing an infrared detecting element, wherein a resistor of the first infrared detecting section and one electrode of the second infrared detecting section are simultaneously formed. 5. A step of forming a conductive thin film on the substrate, and a step of processing the conductive thin film to form a resistor of the first infrared detector and one electrode of the second infrared detector. The method for manufacturing an infrared sensing element according to claim 4, comprising: 6. A method according to claim 6, wherein a conductive thin film is formed on the substrate as a resistor of the first infrared detecting section, and at the same time, another conductive thin film is formed as one electrode of the second infrared detecting section. Item 5. The method for producing an infrared detecting element according to Item 4.