JPH1183634A - Thermal infrared ray detector and method for manufacturing temperature sensing element used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal infrared ray detector which, with its output large and easy mask matching, comprises a pattern of good yield, and a method for manufacturing a temperature sensing element used for it. SOLUTION: On an insulating substrate 12, a first thermocouple pattern 31 comprising one thermoelectric material 10 is formed together with a reflection film 33 at the same time while the reflection film 33 is centered, then, on the insulating substrate 12, a second thermocouple pattern 32v comprising the other thermoelectric material 11 is formed while a warm joint part 14 is positioned in an outside peripheral region of the reflection film 33 not overlapping with the reflection film 33, then, an insulating film 34 is formed over the entire surface of the insulating substrate 12 including the thermocouple comprising both patterns 31 and 32, the reflection film 33 and the warm joint part 14, and then, a photo-detecting film 35 is formed on the insulating film 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal infrared detector in which a thermopile thermosensitive element is provided in a container including a can and a stem, and a method of manufacturing the thermosensitive infrared sensor.

[0002]

2. Description of the Related Art As one of temperature measuring devices for measuring the temperature of an object in a non-contact manner, there is a thermal infrared detector provided with a thermosensitive element made of a thermopile in a container. This thermal infrared detector is a thermo-sensitive element consisting of a thermopile in which a plurality of thermocouples connecting two kinds of thermoelectric materials are connected in series. Wherein the temperature-sensitive element and the heat sink are accommodated in a container comprising a can and a stem having an infrared-transmissive window.

[0003] Since the infrared ray incident on the detector cannot be completely absorbed by the light-receiving portion of the temperature-sensitive element but is partially transmitted, the output of the detector is small. To compensate for this drawback, there has been proposed a thermal infrared detector provided with a temperature-sensitive element having a reflecting portion for reflecting transmitted infrared light to a light receiving portion (Japanese Patent Application Laid-Open No. Hei 6-137943).

[0004]

However, in the conventional thermal infrared detector constructed as described above, the reflection film of the temperature-sensitive element is formed by a process different from the formation of the thermocouple pattern in a silicon substrate which is an insulating substrate. And the number of steps increased accordingly. There are also the following problems. (1) The light-receiving portion of the temperature-sensitive element is formed on an insulating film such as a SiO ₂ film by a gold-black or silver-black deposited film, for example. (2) At the time of mask alignment of the second thermocouple pattern with respect to the first thermocouple pattern, a mark is created on the pattern itself or a portion that affects the pattern, and the mask is aligned using this mark. Therefore, a skilled worker is required, and there is a problem that the yield is not stable. (3) The light receiving section is located at the uppermost position of the temperature sensing element in a state of covering the hot junction, but the warm joining section is located in a substantially central region of the light receiving section. In other words, it is necessary to extend, for example, the second thermocouple pattern to the vicinity of the center of the light receiving unit in order to position the hot junction in the region. For this reason, the yield was poor due to pattern contact due to mask displacement (contact between the first thermocouple pattern and the second thermocouple pattern), pattern peeling during pattern formation, and the like. (4) There is no margin in the space between the two patterns, so that the reflection film is partially covered, and a preferable reflection area cannot be secured. Therefore, the output of the detector did not increase significantly.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned matters, and has as its object to provide a thermal infrared detector and a thermal infrared detector having a large output, easy maximization, and a pattern having a good yield. An object of the present invention is to provide a method for manufacturing a temperature-sensitive element used for a detector.

[0006]

In order to achieve the above object, the present invention provides a plurality of thermoelectric devices in which a heat sink is provided in a container comprising a can and a stem having an infrared transmitting window and two thermoelectric materials are connected. A thermosensitive element composed of a thermopile having a pair connected in series is provided so as to thermally couple the cold junction to the heat sink and to detect the amount of infrared radiation radiated from the temperature measurement target at the hot junction.
Further, a thermal type infrared detector provided with a light receiving portion that receives infrared light so as to cover the hot junction, and provided with a reflecting portion that reflects the infrared light transmitted through the light receiving portion to the light receiving portion,
The reflective portion is provided in a central region of the light receiving portion, and the thermal bonding portion is provided in an outer edge region of the light receiving portion excluding the central region.

Another aspect of the present invention relates to a method of manufacturing a thermosensitive element comprising a thermopile in which a plurality of thermocouples connecting two kinds of thermoelectric materials are connected in series, and used for a thermal infrared detector. On the insulating substrate, a first thermocouple pattern made of one thermoelectric material is formed simultaneously with the reflection film in a state where the reflection film is located at the center, and then, on the insulating substrate, the other thermoelectric material is formed. The formed second thermocouple pattern is formed in a state where the hot junction is located in the outer peripheral region of the reflection film without overlapping with the reflection film, and then, the thermocouple formed by the both patterns is formed. Forming an insulating film on the entire surface of the insulating substrate including the reflective film and the hot junction, subsequently, a light receiving film on the insulating film, in a state where the reflective film is located in the central region thereof, and The temperature is applied to the outer edge area except the central area. And forming in a state where the engagement portion is located.

Another aspect of the present invention relates to a method of manufacturing a thermosensitive element comprising a thermopile in which a plurality of thermocouples connecting two kinds of thermoelectric materials are connected in series and used for a thermal infrared detector. Forming a first thermocouple pattern made of one thermoelectric material on an insulating substrate,
A second thermocouple pattern made of the other thermoelectric material is formed on the insulating substrate at the same time as the reflective film, and the hot junction does not overlap with the reflective film in a state where the reflective film is located at the center. Formed in a state located in the outer peripheral region of the reflective film,
Subsequently, an insulating film is formed on the entire surface of the insulating substrate including the thermocouple formed by the two patterns, the reflective film, and the hot junction, and subsequently, a light-receiving film is formed on the insulating film, and a center thereof is formed. It is characterized by being formed in a state where the reflection film is located in a region and in a state where the hot junction is located in an outer edge region excluding the central region.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show a temperature-sensitive element used in a thermal infrared detector according to an embodiment of the present invention, and FIGS. 4 and 5 show examples of the thermal infrared detector.

First, the main structure of the thermal infrared detector will be described. 4 and 5, reference numeral 1 denotes a container comprising a cylindrical can 2 whose lower side is open and a plate-like stem 3 which closes the lower opening side of the can 2.
Are joined by, for example, pressing (or welding), whereby the container 1 is sealed.

In the center of the upper surface of the can 2, an opening formed by cutting the portion into a rectangular shape by an appropriate size is formed in an infrared-transmissive window (a semiconductor material such as silicon or germanium). One infrared-transmissive window) 4 is formed by soldering with a coating film on the surface of the base material. And, since the semiconductor is used as a base material, electric conductivity and heat conductivity are good. Reference numeral 5 denotes a flange formed at the open lower end of the can 2.

The stem 3 is provided with two lead pins 6 for taking out signals, and the penetrating portion 7 is glass-welded to electrically insulate the lead pin 6 and the stem 3 from each other. b is the glass welded part. Also, 8
Is a ground lead pin fixed to the stem 3 by an appropriate method.

Reference numeral 9 denotes a thermosensitive element, which is composed of two kinds of thermoelectric materials 10, 1
1. A thermopile formed by connecting a plurality of thermocouples connected in series to each other and formed in an annular shape on an insulating substrate 12 such that the cold junction 13 is located outside and the hot junction 14 is located inside. It is. 15a and 15b are contact holes for extracting signals, which are connected to the lead pins 6. Details of the temperature sensing element 9 will be described later with reference to FIGS.

Reference numeral 16 denotes a lower heat sink for holding the temperature sensing element 9, which is provided above the stem 3 via a lead pin 6. Then, the temperature sensing element 9 formed on the insulating substrate 12 is placed on the upper flat portion 19 of the heat sink 16 so as to cover the hole 16a. The lower heat sink 16 is preferably made of a material having a thermal conductivity equal to or higher than that of the first infrared-transmissive window 4 and a material other than copper, such as silicon.

Reference numeral 20 denotes a second infrared transmitting window for transmitting infrared light transmitted through the first infrared transmitting window 4, which is made of a semiconductor material such as silicon or germanium as a base material, and has a wavelength selectable on both sides of the base material. It is formed by forming a conductive multilayer film.
As a result, only infrared light of a specific wavelength is transmitted through the second infrared transmitting window 20. The second infrared transmitting window 20 is, for example, an 8 μm cut-on filter. In addition, since a semiconductor is used as a base material, electric conductivity and thermal conductivity are good.

Reference numeral 21 denotes an upper heat sink which holds the second infrared ray transmitting window 20 so as to face the first infrared ray transmitting window 4, and is formed in a donut shape. It is preferable that the upper heat sink 21 is also made of a material having good thermal conductivity equal to or higher than the first and second infrared transmitting windows 4 and 20. In addition, the second infrared transmitting window 20 is fixed to the upper surface c of the upper heat sink 21 with an adhesive having excellent thermal conductivity.

The temperature sensing element 9 is disposed so as to thermally couple the cold junction 13 to the heat sinks 21 and 16 while being sandwiched between the upper and lower heat sinks 21 and 16.

Hereinafter, the temperature sensing element 9 will be described in detail. 1 and 2, the temperature sensing element 9 is made of a thermopile in which a plurality of thermocouples connecting two kinds of thermoelectric materials 10 and 11 are connected in series, as described above. On a thin disk-shaped insulating substrate (diameter is indicated by r ₀ ) 12 made of a film material or a semiconductor material such as silicon / germanium (preferably a silicon-based material) or the like, a cold bonding portion 13 is provided on the outside, and a hot bonding portion is provided. 14 are formed in a ring shape so as to be located inside, respectively.

At the center of the temperature sensing element 9, a circular light receiving section A (diameter is indicated by r ₁ ) is provided.
In the central region R ₁ , a circular reflecting portion B (diameter is indicated by r ₂ : r ₁ > r ₂ ) in a plan view is provided concentrically with the light receiving portion A. Here, the central region R ₁ of the light receiving portion A is a reflecting portion B
Is a circular area in a plan view having the same diameter as the diameter r ₂ of FIG.

Meanwhile, temperature joint 13 is provided in the outer edge region R ₂ except for the central region R ₁ of the light receiving portion A. Here, the outer edge region R ₂ of the light receiving portion A, is a region corresponding to the annular shape having a width _{L (= r 1 -r 2)} .

Further, a mark 30 for mask alignment is formed on the reflecting portion B. That is, the first thermocouple pattern 31 made of one thermoelectric material 10 [FIG.
(See FIG. 3A), a second thermocouple pattern 32 (see FIG. 3B) made of the other thermoelectric material 11 is formed. In this case, the first thermocouple pattern 32 is formed. The mark 30 is used for mask alignment of the second thermocouple pattern 32 with respect to 31.

In this embodiment, the diameter D of the hole 22 of the upper heat sink 21 is set to be 1.5 times or less the diameter r ₁ of the light receiving portion A of the temperature sensing element 9. Further, both patterns 31, 32, a reflective film 33, and a thermal bonding portion 1 described later.
4. The insulating substrate 12 including the cold junction 13 is covered with the insulating film 34.

To form the temperature sensing element 9, first, as shown in FIG. 3A, a first thermocouple pattern 31 made of the thermoelectric material 10 is formed on the insulating substrate 12. I do. As the thermoelectric material 10, an antimony-based material is preferable.

In this case, the first thermocouple pattern 31 includes a reflection film 33 at the center of the temperature sensing element 9. That is, the reflection film 33 formed at the same time is used as the reflection portion B. This reflective film 3
3 is located at the center on the insulating substrate 12. Moreover, the reflection film 33 has the mark 30 in a part. That is, in the present invention, the thermoelectric material 10 is patterned by photolithography to form the reflection film 33 at the same time, and the mark 30 is also formed on a part of the reflection film 33. Therefore, as compared with the case where the reflection film is formed in a step different from the conventional formation of the thermocouple pattern, the number of steps is reduced and the cost is reduced. And
In this embodiment, the mark 30 is provided at the center of the reflection film 33. The reflection film 33 is, of course, the same material as the thermoelectric material 10.

Subsequently, as shown in FIG. 3B, a second thermocouple pattern 32 made of the thermoelectric material 11 is formed on the insulating substrate 12. As the thermoelectric material 11, a bismuth-based material is preferable.

As a result, the cold junction 13 is located on the outside and the hot junction 14 is located on the inside in an annular shape.
In this case, since the mark 30 is attached to a part of the reflective film 33 and the thermoelectric material 11 is patterned by photolithography, a skilled technique for mask alignment is not required, and the yield is stabilized. The resist used in the above photolithography process may be either negative type or positive type.

Further, as is apparent from FIG. 2, the temperature bonding portion 14 is not formed in the center region R ₁ of the light receiving portion A but in the outer edge region R _2.
Since the thermoelectric materials 10 and 11 were patterned in order to form the same, the pattern 3 was compared to the conventional pattern in which the hot junction was located in the center rather than the outer edge of the light receiving portion.
They can afford the spacing of 1,32, and since it is not necessary to the patterning of the thermoelectric material 10, 11 to the central region R _1, greatly reducing the contact and separation of the patterns 31 and 32 is compared with the conventional As a result, the yield can be improved.

Subsequently, as shown in FIG. 3 (C), contact holes 15a, 15
b, and an insulating film 34 is formed on the entire surface of the insulating substrate 12 including the patterns 31 and 32, the reflective film 33, and the hot and cold junctions 14 and 13. For forming the insulating film 34, a material such as polyimide or SiO ₂ is used.

Finally, as shown in FIG. 3 (D), a light receiving portion A composed of a light receiving film 35 is formed on the insulating film 34. That is, a negative resist film containing carbon is formed, and is patterned into an arbitrary shape by photolithography to form the light receiving film 35. In this case, the patterning is performed so that the central portion of the light receiving film 35 is located directly above the reflective film 33 and the outer edge of the light receiving film 35 is located immediately above the hot junction 13.

As described above, the thermal bonding portion 14 is disposed only immediately below the outer edge of the light receiving film 35, and the reflection film 33 is disposed only immediately below the central portion of the light receiving film 35, and the light transmitted through the light receiving film 35 is transmitted. The structure is such that infrared rays are reflected by the reflection film 33, and since the space between the patterns 31 and 32 can be made large, a reflection area close to approximately 100% can be secured as compared with the related art. Therefore, the output of the detector is also greatly increased.

The light-receiving film 3 is prepared by mixing carbon powder into a negative resist and patterning the mixture by photolithography.
Since the light-receiving portion A is constituted by No. 5, the adhesive strength can be increased as compared with the related art, and the reliability can be improved without peeling.

Further, the thermoelectric materials 10 and 11 and the negative resist film are patterned by photolithography to form patterns 31 and 32, a cold junction 13, a hot junction 14, and a reflection film 3.
3. Since the insulating film 34 and the light receiving film 35 are formed, a single-sided thin film structure can be obtained, the number of steps can be reduced, and the yield can be improved, as compared with the related art.

In the present invention, the reflective film at the center of the thermosensitive element may be formed simultaneously with the mask 32 by patterning the thermoelectric material 11 by photolithography.

The resist used for the formation of the light receiving film may be a positive resist other than the negative resist. Furthermore, although a combination of an antimony-based material and a bismuth-based material has been described as the thermoelectric materials 10 and 11, other thermocouple materials may be used.

[0036]

The present invention is embodied in the above-described embodiment and has the following effects.

According to the present invention, while providing the reflecting portion in the central region of the light receiving portion and providing the hot junction portion in the outer edge region excluding the central region of the light receiving portion, the space between the patterns can be made large, and Since the thermoelectric material does not need to be patterned until then, the contact and peeling of the pattern are greatly reduced as compared with the conventional case, and the yield can be improved.

Since a sufficient space can be provided between the patterns, a reflection area close to approximately 100% can be secured as compared with the conventional case. Therefore, the output of the detector is also greatly increased.

A pattern for patterning the reflective film simultaneously with the pattern can be used, whereby the number of steps can be reduced and an inexpensive thermal infrared detector can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the overall configuration of a temperature-sensitive element according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part configuration of a temperature-sensitive element in the embodiment.

FIG. 3 is a diagram for explaining a method for producing a temperature-sensitive element in the embodiment.

FIG. 4 is an explanatory diagram of an overall configuration of a thermal infrared detector including the temperature-sensitive element of the embodiment.

FIG. 5 is an exploded perspective view of a thermal infrared detector provided with the temperature-sensitive element of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Can, 3 ... Stem, 4 ... Infrared transparent window, 9 ... Thermosensitive element, 10, 11 ... Thermoelectric material, 14 ... Hot junction, 12 ... Insulating substrate, 30 ... Mark, 31 ... No. 1 thermocouple pattern, 32 ... second thermocouple pattern, 33 ... reflective film,
Reference numeral 34 denotes an insulating film, 35 denotes a light receiving film, R ₁ denotes a central region of the light receiving portion, R ₂ denotes an outer edge region of the light receiving portion, A denotes a light receiving portion, and B denotes a reflecting portion.

Claims (8)

[Claims] 1. A thermosensitive element comprising a thermopile in which a heat sink is provided in a container comprising a can having an infrared transmitting window and a stem, and a plurality of thermocouples connecting two kinds of thermoelectric materials are connected in series. A light-receiving section for thermally coupling the cold junction to the heat sink and for detecting the amount of infrared radiation radiated from the temperature measurement target at the hot junction, and further receiving infrared rays so as to cover the hot junction; A thermal infrared detector provided with a reflecting portion for reflecting infrared light transmitted through the light receiving portion to the light receiving portion, wherein the reflecting portion is provided in a central region of the light receiving portion, while the central region of the light receiving portion is provided. A thermal infrared detector characterized in that the thermal bonding portion is provided in an outer edge region except for (1). 2. A method for manufacturing a thermosensitive element used in a thermal infrared detector, comprising a thermopile in which a plurality of thermocouples in which two kinds of thermoelectric materials are connected in series, wherein a reflective film is formed on an insulating substrate. A first thermocouple pattern made of one thermoelectric material is formed simultaneously with the reflection film in a state located at the center, and then a second thermocouple pattern made of the other thermoelectric material is formed on the insulating substrate. Is formed in a state where the hot junction is located in the outer peripheral region of the reflection film without overlapping with the reflection film, and then, the thermocouple, the reflection film, and the hot junction formed by the both patterns are formed. An insulating film is formed on the entire surface of the insulating substrate including the light-receiving film on the insulating film, in a state where the reflective film is located in a central region thereof, and in an outer edge region excluding the central region. Formed with the hot junction located A method for producing a temperature-sensitive element used in a thermal infrared detector. 3. The method according to claim 2, wherein an antimony-based material and a bismuth-based material are used as the two kinds of thermoelectric materials. 4. The thermal imaging device according to claim 2, wherein the light receiving film is formed by forming a negative resist film containing carbon on the insulating film and patterning the negative resist film into an arbitrary shape. Of manufacturing a temperature-sensitive element used in a type infrared detector. 5. The method according to claim 2, wherein the reflection film is formed of the same material as the one thermoelectric material. 6. The heat according to claim 2, wherein a mark for mask alignment of the second thermocouple pattern with respect to the first thermocouple pattern is formed on the reflection film. Of manufacturing a temperature-sensitive element used in a type infrared detector. 7. A method for manufacturing a thermosensitive element used in a thermal infrared detector, comprising a thermopile in which a plurality of thermocouples connected to two kinds of thermoelectric materials are connected in series, wherein one thermoelectric material is provided on an insulating substrate. Forming a first thermocouple pattern formed of the other thermoelectric material on the insulating substrate, simultaneously with the reflection film, and the reflection film in the center In a state where it is located, the thermal bonding portion is formed so as not to overlap with the reflective film and is located in an outer peripheral region of the reflective film, and subsequently, the thermocouple, the reflective film and the temperature formed by the both patterns are formed. Forming an insulating film on the entire surface of the insulating substrate including the bonding portion, subsequently forming a light-receiving film on the insulating film, the reflective film being positioned in a central region thereof, and an outer edge excluding the central region. In the state where the hot junction is located in the area A method for manufacturing a temperature-sensitive element used for a thermal infrared detector, characterized by being formed. 8. The method according to claim 7, wherein the reflection film is formed of the same material as the other thermoelectric material.