JPH058447U - Thermopile type infrared sensor - Google Patents

Abstract

(57) [Summary] [Structure] A substrate 1 having a pit portion 4 and a heat sink 3, and a diaphragm 5 provided on the substrate 1 at the pit portion 4.
A front surface insulating film 2 and a plurality of thermocouples 8 made of different kinds of metals are connected in series, and a diaphragm 5 is provided.
The thermopile 9 serves as the hot contact portion 11 above and the cold contact portion 10 above the heat sink 3. [Effects] Since a black body whose characteristics change significantly with respect to heat and atmosphere is not used, it is possible to obtain a thermopile type infrared sensor that is stable against heat and atmosphere.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to a structure of a thermopile type infrared sensor.

[0002]

[Prior art]

  The structure and operation of the conventional thermopile type infrared sensor are shown in FIGS. 2 and 3. And explain. FIG. 2 shows a first conventional example, and FIG. 3 shows a second conventional example. Figure 2 ( 3A and FIG. 3A respectively show the structure of a conventional thermopile type infrared sensor. 2 (b) and 3 (b) are plan views of the conventional structure, respectively. It is sectional drawing which shows the structure of a mopile type infrared sensor.

[0003]   First, the structure of the thermopile type infrared sensor in the first conventional example is shown in FIG. It demonstrates using.

[0004]   As the substrate 1, a silicon (100) oriented substrate is used. On this board 1 Forms the front surface insulating film 2. Furthermore, different kinds of gold are deposited on the front surface insulating film 2. A plurality of thermocouples 8 made of metal are connected in series and a thermopile extraction electrode 12 is connected. A thermopile 9 connected to the above is provided. At this time, the cold junction 1 of the thermopile 9 0 is placed on the heat sink 3 consisting of the substrate 1 and the front surface insulating film 2, and the thermostat The hot contact portion 11 of the pile 9 is arranged on the diaphragm 5.

[0005]   Further, a black body 6 made of an ultrafine particle film of a metal such as gold (Au) or bismuth. Are arranged in the central portion of the diaphragm 5 near the hot junction 11. This black body 6 In order to prevent short circuit between the individual hot junction parts 11 of the thermopile 9, the hot junction parts 11 It is placed at a distance of several μm from.

[0006]   Further, a pit portion 4 is provided on the back surface of the substrate 1. The pit portion 4 is the substrate 1 Use a strong alkaline solution such as potassium hydroxide (KOH) or hydrazine from the back of the Then, the silicon that is the substrate 1 is anisotropically etched to form the pit portion 4. It In the pit portion 4, the entire substrate 1 is etched and only the front surface insulating film 2 remains. The front surface insulating film 2 constitutes the diaphragm 5.

[0007]   The thermopile type infrared sensor shown in FIG. 2 is used, for example, in a radiation thermometer. Used. The operation of the thermopile type infrared sensor shown in FIG. 2 is as follows. become.

[0008]   The black body 6 absorbs the infrared rays emitted from the temperature measurement object and converts it into heat, which has a small heat capacity. Of the thermopile 9 placed on the diaphragm 6 by heating The hot junction 11 is heated. At this time, the cold junction portion 10 of the thermopile 9 has a heat capacity Since it is placed on the large heat sink 3, the temperature hardly rises. this Therefore, a temperature difference occurs between the hot junction 11 and the cold junction 10. This hot junction 10 Due to the temperature difference between the cold junction 11 and the cold junction 11, thermoelectromotive force is generated in the thermopile 9, The temperature of a fixed product can be measured.

[0009]   Next, the structure of the thermopile type infrared sensor in the second conventional example is shown in FIG. It demonstrates using.

[0010]   The thermopile infrared sensor shown in FIG. 3 is the thermopile infrared sensor shown in FIG. Similar to the line sensor, the front surface insulating film 2 is formed on the substrate 1. Furthermore, this main A plurality of thermocouples 8 made of different metals are connected in series on the surface insulating film 2 and The thermopile 9 connected to the pile extraction electrode 12 is formed. At this time the thermo The cold contact part 10 of the pile 9 is on the heat sink 3, and the hot contact part 11 is the diaphragm 3 Place it on top.

[0011]   Further, as shown in FIG. 3, the insulation is formed so as to cover the hot junction 11 of the thermopile 9. An under-blackbody insulating film 7 having an edge property is provided. Method of patterning this under-blackbody insulating film 7 May use a normal photo-etching technique, or provide an opening in the metal mask. The so-called mask vapor deposition method or the like for forming the under-blackbody insulating film 7 in the opening is used. Is also good. The size of the insulating film 7 under the black body is the same as that of the black body 6 to be formed later. It should be slightly larger.

[0012]   Further, the black body 6 is provided on the insulating film 7 under the black body. The size of this black body 6 is The hot junction 11 of the thermopile 9 is slightly smaller than the size of the diaphragm 5. It should be large enough to cover all. At this time, the hot junction 11 of the thermopile 9 and the black Insulation with the body 6 is maintained by the under-blackbody insulating film 7.

[0013]   Further, as in the thermopile type infrared sensor shown in FIG. Then, the diaphragm 5 made of the front surface insulating film 2 is formed.

[0014]   Next, the operation of the thermopile type infrared sensor shown in FIG. 3 will be described below.

[0015]   Infrared rays radiated from the temperature measurement object are received by the black body 6 and converted into heat, and this heat becomes black. Conducting through the underbody insulating film 7, the hot junction 11 of the thermopile 9 and the diaphragm Heat the entire ram 5.

[0016]   At this time, the cold junction 10 of the thermopile 9 is placed on the heat sink 3. Therefore, the temperature hardly rises, and as a result, the temperature between the hot junction portion 11 and the cold junction portion 10 is increased. There is a temperature difference.

[0017]   Due to the temperature difference between the cold junction 10 and the hot junction 11, the thermopile 9 Thermoelectromotive force is generated, and temperature can be measured.

[0018]   The thermopile type infrared sensor shown in FIG. 3 is better than the thermopile shown in FIG. The distance from the black body 6 to the hot junction 11 can be set shorter than the red infrared sensor. Therefore, the output becomes high.

[0019]

[Problems to be solved by the device]

  Thermopile infrared in the conventional example of the two types of structures shown in FIGS. 2 and 3 above. The line sensor uses a red sensor to efficiently receive infrared rays emitted from the temperature measurement object. A black body 6 with a very high external absorption rate of about 80% to 90% is provided on the infrared receiving surface. is doing.

[0020]   However, the thermopile type infrared sensor shown in FIG. Short-circuit the hot junction 11 of the thermopile 9 by the black body 6 made of metal such as sunflower. To prevent this, the black body 6 cannot be directly formed on the hot junction 11 of the thermopile 9. Absent. For this reason, the thermostat is formed through the under-blackbody insulating film 7 having a thickness of at least several hundreds nm. The black body 6 is arranged on the hot contact portion 11 of the pile 9.

[0021]   As a result, in the thermopile type infrared sensor shown in FIG. The heat is transferred from the black body 6 to the hot junction 11 via the heat. Therefore, from the black body 6 to the hot junction There is a loss of about 60% of the heat conduction to 11.

[0022]   Therefore, the amount of heat of about 30% to 40% of the infrared rays incident on the black body 6 causes Since 11 is heated, it is very inefficient.

[0023]   Furthermore, in the thermopile type infrared sensor shown in FIG. As for heat conduction to 11, heat is transmitted through the front surface insulating film 2. Therefore, as shown in FIG. Thermopile type infrared sensors are more inefficient because of the higher heat loss. Become

[0024]   In addition, the black body 6 made of an ultrafine particle film of a metal such as gold or bismuth has a It is very sensitive to air and causes aggregation or alteration. For this, with blackbody 6 The infrared absorption rate of the There is a problem of getting rid of.

[0025]   Therefore, the purpose of the present invention is to solve the above-mentioned problems and to be stable against heat and atmosphere. Another object is to provide a structure of a thermopile type infrared sensor.

[0026]

[Means for Solving the Problems]

  In order to achieve the above object, the thermopile type infrared sensor of the present invention is as follows. It is characterized by adopting the structure shown in.

[0027]   That is, a substrate having a pit portion and a heat sink and a pin provided on the substrate. The front surface insulating film that becomes the diaphragm at the bottom and the thermocouples made of different metals Individually connected in series and placed on the front surface insulating film, and on the diaphragm a hot junction On the heat sink, there is a thermopile that serves as a cold junction.

[0028]   At least one of the thermocouples made of different metals is composed of an infrared absorber.

[0029]

【Example】

  An embodiment of the thermopile type infrared sensor of the present invention will be described below with reference to FIG. It FIG. 1 (a) shows a plan view of a thermopile type infrared sensor of the present invention. 1 (b) is a sectional view thereof.

[0030]   As shown in FIG. 1, a front surface insulating film 2 is formed on the front surface of the substrate 1. This one The front surface insulating film 2 is a pit formed by etching the substrate 1 from the back side. The diaphragm 5 is formed on the portion 4, and the heat sink 3 is formed on the substrate 1 together with the substrate 1. Make up.

[0031]   A plurality of thermocouples 8 made of different metals are connected in series on the front surface insulating film 2. A thermopile 9 is provided. In this thermopile 9, the cold junction 10 has a heat shield. The hot contact portion 11 is arranged on the diaphragm 3 so as to be on the diaphragm 5.   Furthermore, at least one of the thermocouples 8 made of different metals is an infrared absorber. It consists of.

[0032]   Furthermore, in order to take the output of the thermopile 9, it connects with this thermopile 9. A thermopile extraction electrode 12 is provided.

[0033]   The thermopile type infrared sensor of the present invention shown in FIG. 1 is shown in FIGS. 2 and 3. Unlike the conventional example, no black body is formed. That is, instead of a black body, a thermocouple 8 It absorbs external rays and converts them into heat.

[0034]   The operation of the thermopile type infrared sensor according to the present invention will be described below.   At least one of the thermocouples 8 receives infrared rays that are incident from the measurement object for measuring the amount of infrared rays. Is absorbed by the material and heats the thermopile 9.

[0035]   Since the hot junction 11 of the thermopile 9 is provided on the diaphragm 5, The temperature rises gently. On the other hand, the cold contact portion 10 of the thermopile 9 is Since it is provided above, the temperature hardly changes. Therefore, the hot junction 11 and the cold A temperature difference occurs between the contact portion 10. Between the cold junction 10 and the hot junction 11 A thermoelectromotive force corresponding to the temperature difference is generated in each of the thermocouples 8, and each thermoelectromotive force is generated. The forces are added together to generate a voltage in the thermopile 9.

[0036]   The generated voltage is input by extracting it from the thermopile extraction electrode 12. The amount of infrared rays emitted can be detected.

[0037]   At this time, the material itself of the thermocouple 8 constituting the thermopile 9 absorbs infrared rays, When the temperature of the hot junction 11 rises, the black body absorbs infrared rays and absorbs heat as in the conventional case. There is no loss in transmission.   Therefore, the infrared absorptivity of the thermopile 9 material itself is the infrared absorptivity of the black body. However, even if it is lower than the Absent.   Further, the area of the hot junction 11 that absorbs infrared rays of the thermopile 9 is increased. The output of the thermopile type infrared sensor is increased rather than the conventional one. It becomes possible.

[0038]   Therefore, it is not necessary to use a black body that is extremely vulnerable to heat or the atmosphere. A stable thermopile infrared sensor can be obtained.

[0039]   Further, although not shown, an insulating film is formed only on the cold junction portion 10 to prevent the formation of gold or the like. A metal film that reflects infrared rays is placed on the cold junction 10 so that the infrared rays are not visible at the cold junction 10. It is possible to absorb infrared rays only by the hot junction 11 if configured to reflect And the output becomes higher.

[0040]   Next, referring to FIG. 1, a method for manufacturing a thermopile type infrared sensor according to the present invention will be described. explain.

[0041]   As the substrate 1, a substrate having a (100) orientation of silicon is used. A silicon nitride film, a silicon oxide film, or the like is used as a plasma insulating film 2 on the front surface. It is formed by the chemical vapor deposition method.

[0042]   On this front surface insulating film 2, a thermoelectric material composed of bismuth on one side and antimony on the other side Form pair 8.

[0043]   Here, an example of using antimony as the material of the thermocouple 8 is given. Chimon has a high infrared absorption rate of about 35% over a wide wavelength range. Is a very good infrared absorber. Especially, antimony is from around room temperature Infrared rays are emitted over the entire wavelength range of infrared rays emitted from substances up to several hundred degrees Celsius. Since it absorbs, it can be applied to a radiation thermometer in a wide temperature range.

[0044]   Of course, alloyed with other substances such as tellurium added to antimony Also has a high infrared absorption rate, so the thermopile type infrared sensor of the present invention Can be applied to.

[0045]   Next, in order to extract the output of the thermopile 9, a metal such as gold is used as a normal foil. The thermopile extraction electrode 12 is formed by patterning using a photoetching technique. To achieve.

[0046]   At this time, although not shown, at the same time as the step of forming the thermopile extraction electrode 12, In order to improve the adhesiveness of the thermocouple 8 contacts made of dissimilar metals, A metal such as gold may be formed.

[0047]   As a method for forming the thermocouple 8, a photosensitive resin is exposed and developed in advance. To form a photosensitive resin having an opening in a region where a desired metal is to be formed, and then a desired resin is formed. The desired metal is formed by forming the metal by vacuum deposition and removing the photosensitive resin. The so-called lift-off method for patterning is used.

[0048]   A plurality of the thermocouples 8 are connected in series to form a thermopile 9. This The thermopile 9 has a hot contact portion 11 on a diaphragm 5 formed in a later step, The cold contact portion 10 is arranged on the heat sink 3.

[0049]   Then, using a strong alkaline solution such as hydrazine from the back surface of the substrate 1, silico Anisotropic etching is performed to form the pit portion 4. Patterning of pit section 4 As a method of etching, although not shown, the back surface of the substrate 1 is resistant to etching with a strong alkaline solution. The silicon nitride film, etc., which has a high etching property, is covered, and this silicon nitride film is patterned. To form an etching mask.

[0050]   Here, in the pit portion 4, all the silicon of the substrate 1 is etched to insulate the front surface. Only the film 2 remains, and the diaphragm 5 made of this front surface insulating film 2 is formed, The mopile type infrared sensor is completed. In addition, the substrate on which the silicon of the substrate 1 remains In the peripheral portion of the plate 1, the substrate 1 and the front surface insulating film 2 are compared with the diaphragm 5. As a result, the heat sink 3 has a very large heat capacity.

[0051]

[Effect of device]

  As described above, according to the present invention, it is highly resistant to changes in heat and atmosphere. It is possible to obtain a thermopile type infrared sensor that operates stably.   Furthermore, since no black body is formed, the structure is simplified and the cost is reduced. Can be done. Furthermore, by selecting the thermocouple material, a very wide temperature range can be obtained. Thermopile type infrared sensor that can be applied to a radiation thermometer You can get a sir.

[Brief description of drawings]

FIG. 1 is a view showing the structure of a thermopile type infrared sensor according to an embodiment of the present invention.

FIG. 2 is a view showing a structure of a conventional thermopile type infrared sensor.

FIG. 3 is a view showing a structure of a conventional thermopile type infrared sensor.

[Explanation of symbols]

1 substrate 2 Front surface insulation film 3 heat sink 4 pit section 5 diaphragm 8 thermocouple 9 Thermopile 10 Cold junction 11 Hot junction

Claims (2)

[Scope of utility model registration request] 1. A substrate having a pit portion and a heat sink, a front surface insulating film which is provided on the substrate and serves as a diaphragm in the pit portion, and a plurality of thermocouples made of different metals are connected in series. A thermopile type infrared sensor comprising: a thermopile arranged on the front surface insulating film and serving as a hot contact portion on the diaphragm and a cold contact portion on the heat sink. 2. A thermopile type infrared sensor, wherein at least one of the thermocouples made of different metals according to claim 1 is an infrared absorber.