WO2013168708A1

WO2013168708A1 - Thermopile infrared sensor and method for manufacturing same

Info

Publication number: WO2013168708A1
Application number: PCT/JP2013/062842
Authority: WO
Inventors: 恭輔尾崎; 渡部　弘也; 聡和賀
Original assignee: アルプス電気株式会社
Priority date: 2012-05-09
Filing date: 2013-05-07
Publication date: 2013-11-14
Also published as: JP2015132470A

Abstract

[Problem] The purpose of the present invention is to provide a thermopile infrared sensor and a method for manufacturing same, in which sensitivity can be improved and the formation of an infrared-absorbing film that covers the cold junction is prevented. [Solution] A thermopile infrared sensor (10) having a substrate (11), a thermopile element (30), and an infrared-absorbing film (21), having the thermopile element (30) and the infrared-absorbing film (21) formed on the substrate (11), and having a temperature difference that can be detected between the heat junction (34) and the cold junction (35) of the thermopile element (30), wherein a range-restricting member (20) for restricting the formation range of the infrared-absorbing film (21) is formed between the infrared-absorbing film (21) and the cold junction (35).

Description

Thermopile type infrared sensor and manufacturing method thereof

The present invention relates to a thermopile type infrared sensor and a manufacturing method thereof, and more particularly, to a thermopile type infrared sensor having an infrared absorption film and a manufacturing method thereof.

Infrared sensors are used in industrial equipment, thermometers, and the like to detect infrared rays from an object without contact and measure the temperature. A thermopile type infrared sensor is known as such an infrared sensor.

The conventional thermopile type infrared sensor includes a base material, a thermopile element in which two different materials are alternately connected in series, and an infrared absorption film. The base material includes a membrane as a thin portion and a base portion as a thick portion formed around the thin portion. The thermopile element has a hot junction and a cold junction, and the cold junction is formed on the base as a thick portion, and the hot junction is formed on a membrane as a thin portion. When the thermopile type infrared sensor receives infrared rays, a temperature difference occurs between the cold junction and the hot junction, and an electromotive force is generated due to the Seebeck effect. Infrared rays are detected based on this electromotive force.

In recent years, mounting of thermopile infrared sensors to mobile devices has been studied, and miniaturization is desired. In this case, since the distance between the cold junction and the hot junction of the thermopile element is reduced and it is difficult to increase the temperature difference between the contacts, the sensitivity of the thermopile infrared sensor is lowered. In order to improve the sensitivity even when the thermopile type infrared sensor is downsized, an infrared absorption film is provided so as to cover the hot junction, and infrared rays incident from the outside are absorbed by the infrared absorption film, And it is converted into heat. As a result, the temperature of the hot junction increases, the temperature difference between the cold junction and the hot junction can be effectively increased, and the sensitivity of the thermopile infrared sensor can be improved.

Such a thermopile type infrared sensor having an infrared absorption film is described in, for example, Patent Document 1 below.

JP 2000-065638 A

FIG. 13 is a plan view for explaining the problems of the thermopile infrared sensor 101 of the conventional example, and FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. As shown in FIG. 13, the thermopile element 130 in which the first thermoelectric material layer 131 and the second thermoelectric material layer 132 are alternately connected is formed on the base 110. As shown in FIG. 14, the hot junction 134 to which the first thermoelectric material layer 131 and the second thermoelectric material layer 132 are connected is formed in the membrane 112 as the thin portion 112a, and the cold junction 135 is the thick portion 111a. As shown in FIG. An infrared absorption film 121 is formed at the center of the membrane 112 so as to cover the hot junction 134.

The infrared absorbing film 121 is formed by applying a solution containing an infrared absorbing material by a screen printing method and then curing. However, since the solution containing the infrared absorbing material has fluidity, it flows outside the initial solution formation range 121a when applied and expands to the actual formation range 121b. Therefore, as shown in FIGS. 13 and 14, the infrared absorption film 121 may be formed so as to cover the cold junction 135.

In particular, when the thermopile infrared sensor 101 is downsized, the distance between the cold junction 135 and the hot junction 134 is reduced, so that the solution containing the infrared absorbing material flows and spreads, and the cold junction 135 is easily covered. Further, the distance between the adjacent first thermoelectric material layer 131 and the second thermoelectric material layer 132 is also reduced. As a result, the solution containing the infrared absorbing material easily flows through the narrow concave groove formed between the adjacent thermoelectric material layers. For this reason, the actual formation range 121b extends outside the initial solution formation range 121a.

Furthermore, in order to improve the sensitivity of the thermopile type infrared sensor 101, it is necessary to increase the temperature difference between the cold junction 135 and the hot junction 134. In order to increase the temperature rise of the hot junction 134 when infrared rays are incident from the outside, it is desirable to increase the absorption amount of infrared rays by forming the infrared absorption film 121 thick. However, if the infrared absorbing film 121 in the vicinity of the hot junction 134 is to be formed thick, the actual formation range 121b of the solution containing the infrared absorbing material is more easily spread outward than the initial solution forming range 121a. The absorption film 121 is formed to cover the cold junction 135.

As shown in FIG. 13 and FIG. 14, when the solution containing the infrared absorbing material spreads and reaches the place where it covers the cold junction 135 and is cured to form the infrared absorbing film 121, the thermopile infrared sensor 101 is formed. When infrared rays are received, not only the hot junction 134 but also the cold junction 135 rises in temperature due to the infrared absorption film 121, so the temperature difference between the hot junction 134 and the cold junction 135 becomes small. For this reason, the subject that the sensitivity of the thermopile type infrared sensor 101 falls arises.

The present invention provides a thermopile type infrared sensor capable of improving the sensitivity by solving the above problems and preventing the infrared absorption film from being formed so as to cover the cold junction, and a method for manufacturing the same. With the goal.

The thermopile type infrared sensor of the present invention includes a base material, a thermopile element, and an infrared absorption film, and the thermopile element and the infrared absorption film are formed on the base material, and the thermopile element is cooled. A thermopile infrared sensor capable of detecting a temperature difference between a contact point and a hot contact point, and a range regulating member for regulating a formation range of the infrared absorption layer is formed between the infrared absorption layer and the cold junction. It is characterized by being.

According to this, even when the solution containing the infrared absorbing material flows when forming the infrared absorbing film, the flow of the solution containing the infrared absorbing material is regulated by the range regulating member. That is, it is possible to prevent the solution containing the infrared absorbing material from flowing and spreading outside the initial solution formation range. Thereby, it can prevent that an infrared rays absorption film is formed so that a cold junction may be covered. Moreover, when the infrared rays from the outside are received, since the cold junction is not covered with the infrared absorption film, the temperature rise is suppressed and the temperature difference between the hot junction and the cold junction can be increased. Therefore, even if the area is reduced, the sensor output from the thermopile element can be increased, and the sensitivity of the thermopile infrared sensor can be improved.

According to the thermopile type infrared sensor of the present invention, it is possible to improve the sensitivity by preventing the infrared absorption film from being formed to cover the cold junction.

In the thermopile type infrared sensor of the present invention, it is preferable that the range regulating member is formed between the hot junction and the cold junction, and the infrared absorbing film is formed so as to cover the hot junction. is there. By forming the range regulating member between the hot junction and the cold junction, it is possible to prevent the solution containing the infrared absorbing material from flowing and spreading outside the formation range of the initial solution. . Therefore, it is possible to prevent the infrared absorption film from being formed so as to cover the cold junction. Moreover, since the infrared absorption film is formed so as to cover the hot junction, it is possible to suppress the temperature rise of the cold junction and effectively increase the temperature of the hot junction. Therefore, the temperature difference between the cold junction and the hot junction can be increased, and the sensitivity of the thermopile infrared sensor can be effectively improved.

In the thermopile type infrared sensor of the present invention, it is preferable that the range restricting member is formed on the warm contact and the infrared absorbing film is formed close to the warm contact. According to this, by forming the range regulating member on the hot junction, it is possible to prevent the solution containing the infrared absorbing material from flowing and spreading outside the formation range of the initial solution. Therefore, it is possible to prevent the infrared absorption film from being formed so as to cover the cold junction. Further, since the infrared absorption film is formed close to the hot junction, it is possible to suppress the temperature rise of the cold junction and effectively increase the temperature of the hot junction. Therefore, the temperature difference between the cold junction and the hot junction can be increased, and the sensitivity of the thermopile infrared sensor can be effectively improved.

In the thermopile type infrared sensor of the present invention, the thermopile element has a planar pattern having a meander-shaped thermoelectric material, and the range restricting member in a cross-sectional view in the width direction of the meander-shaped thermopile element. Is preferably formed by filling gaps between the thermoelectric materials. By forming the range regulating member in this manner, when the infrared absorption film is formed, the solution containing the infrared absorption material is less likely to flow through the gap between the thermoelectric materials adjacent in the width direction. As a result, it is possible to reliably prevent the infrared absorption film from being formed so as to cover the cold junction.

In the thermopile type infrared sensor of the present invention, the base material has a thin portion and a thick portion formed around the thin portion, and the hot junction is formed in the thin portion and the cold junction. Is formed in the thick portion, and the range restricting member is preferably formed so as to surround a central portion of the thin portion. According to this, since the hot junction and the infrared absorption film are formed in a thin portion having a small heat capacity, and the cold junction is formed in a thick portion having a large heat capacity, the temperature difference between the hot junction and the cold junction is further increased. Is possible. Further, by forming the range restricting member so as to surround the central portion of the thin-walled portion, the flow of the solution containing the infrared absorbing material is restricted, and the solution containing the infrared absorbing material is outside the initial solution forming range. Can be reliably prevented from flowing and spreading. Therefore, the sensitivity of the thermopile infrared sensor can be effectively improved.

In the thermopile type infrared sensor of the present invention, it is preferable that the range restricting member is a convex wall portion. According to this, when the infrared absorption film is formed, the solution containing the infrared absorption material is blocked by the convex wall portion and reliably prevents the solution from flowing to the cold junction side from the formation range of the infrared absorption film. can do.

In the thermopile type infrared sensor of the present invention, it is preferable that the infrared absorption film is formed higher than a height of the range regulating member. By so doing, the infrared absorption amount of the infrared absorption film is increased, and the temperature difference between the hot junction and the cold junction can be increased, so that the sensitivity of the thermopile infrared sensor can be further improved.

The manufacturing method of the thermopile type infrared sensor of the present invention is:
(A) preparing the base material on which the thermopile element is formed, setting a formation range of the infrared absorption film, and setting a range regulating member for regulating the formation range of the infrared absorption film as the formation range Forming between the cold junctions;
(B) applying a solution containing an infrared absorbing material to the formation range to form the infrared absorbing film.

According to this, even when the solution containing the infrared absorbing material flows in the step (b), the solution containing the infrared absorbing material is regulated by the range regulating member. That is, it is possible to prevent the solution containing the infrared absorbing material from flowing and spreading outside the initial solution formation range. Thereby, it can prevent that an infrared rays absorption film is formed so that a cold junction may be covered. Moreover, when the infrared rays from the outside are received, since the cold junction is not covered with the infrared absorption film, the temperature rise is suppressed and the temperature difference between the hot junction and the cold junction can be increased. Therefore, even if the area is reduced, the sensor output from the thermopile element can be increased, and the sensitivity of the thermopile infrared sensor can be improved.

According to the manufacturing method of the thermopile type infrared sensor of the present invention, it is possible to prevent the infrared absorption film from being formed so as to cover the cold junction and to improve the sensitivity.

In the method for manufacturing a thermopile type infrared sensor of the present invention, it is preferable that after the step (a), a step of forming a thin portion by removing the base material at a position overlapping the hot junction by etching is included. Thereby, the heat capacity of the location where the hot junction is formed can be reduced, and the temperature difference between the hot junction and the cold junction can be increased.

In the step (a), it is preferable that the range regulating member is formed so as to surround the central portion of the thin portion. According to this, the flow of the solution containing the infrared absorbing material is regulated, and the solution containing the infrared absorbing material can be reliably prevented from flowing and spreading outside the initial solution formation range. Therefore, it is possible to improve the sensitivity of the thermopile type infrared sensor by preventing the infrared absorption film from being formed so as to cover the cold junction.

In the manufacturing method of the thermopile type infrared sensor of the present invention, it is preferable that in the step (b), the solution is applied so that the solution is higher than the height of the range regulating member. According to this, the infrared absorption film can be formed thick using the surface tension of the solution. Therefore, the infrared absorption amount of the infrared absorption film is increased, the temperature difference between the hot junction and the cold junction can be increased, and the sensitivity of the thermopile infrared sensor can be further improved.

In the step (b), the solution is preferably applied by an ink jet printing method. According to this, when applying the solution containing the infrared absorbing material, the thin portion can be applied and formed in a non-contact manner, and the thin portion can be prevented from being destroyed in the manufacturing process.

In the step (b), the infrared absorbing film is preferably formed by curing the solution by heat curing or ultraviolet curing. According to this, the infrared ray absorbing film can be formed by curing the solution containing the infrared ray absorbing material in a short time with a simple process.

According to the thermopile type infrared sensor and the method of manufacturing the same of the present invention, even when the solution containing the infrared absorbing material flows when forming the infrared absorbing film, the flow of the solution containing the infrared absorbing material by the range regulating member Is regulated. That is, it is possible to prevent the solution containing the infrared absorbing material from flowing and spreading outside the initial solution formation range. Thereby, it can prevent that an infrared rays absorption film is formed so that a cold junction may be covered. Moreover, when the infrared rays from the outside are received, since the cold junction is not covered with the infrared absorption film, the temperature rise is suppressed and the temperature difference between the hot junction and the cold junction can be increased. Therefore, even if the area is reduced, the sensor output from the thermopile element can be increased, and the sensitivity of the thermopile infrared sensor can be improved.

According to the thermopile type infrared sensor and the manufacturing method thereof of the present invention, it is possible to prevent the infrared absorption film from being formed so as to cover the cold junction and to improve the sensitivity.

It is a top view of the thermopile type infrared sensor in the embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. The partial enlarged plan view (a) of the area | region A enclosed with the dashed-two dotted line of FIG. 1, and a partial expanded sectional view (b) are shown. It is a top view which shows the thermopile type infrared sensor in a 1st modification. FIG. 5 shows a cross-sectional view taken along line VV in FIG. 4. It is a top view which shows the thermopile type infrared sensor in a 2nd modification. Sectional drawing when it cut | disconnects by the VII-VII line of FIG. 6 is shown. It is a top view which shows the thermopile type infrared sensor in a 3rd modification. FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. It is a graph which shows the relationship between the temperature of a measuring object, and a sensor output about the thermopile type infrared sensor of this embodiment. It is process drawing which shows the manufacturing method of a thermopile type infrared sensor. It is process drawing which shows the manufacturing method of a thermopile type infrared sensor. It is a top view of the thermopile type infrared sensor in a prior art example. FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG.

Hereinafter, a thermopile type infrared sensor according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the top view of the thermopile type infrared sensor 1 of this embodiment is shown. FIG. 2 shows a cross-sectional view of the thermopile infrared sensor 1 taken along the line II-II in FIG. It should be noted that the dimensional ratios in the drawings are appropriately changed for easy understanding.

The thermopile type infrared sensor 1 of the present embodiment is configured to include a base material 10, a thermopile element 30 and an infrared absorption film 21 formed on the base material 10, as shown in FIGS. As shown in FIG. 2, the base material 10 includes a base 11 and a membrane 12. A cavity 13 is formed at the center of the base 11, and a membrane 12 is formed so as to cover the cavity 13. The membrane 12 is formed as a thin portion 12a, and a portion of the base 11 where the cavity 13 is not formed is formed around the membrane 12 as a thick portion 11a. In the present embodiment, a silicon substrate can be used as the base 11, and an insulating thin film such as a silicon nitride film or a silicon oxide film is used for the membrane 12.

As shown in FIG. 1, the thermopile element 30 has a planar pattern having a meander-shaped thermoelectric material layer, and first thermoelectric material layers 31 and second thermoelectric material layers 32 are alternately arranged in series. Connected to form a meander. And among the connection parts of the 1st thermoelectric material layer 31 and the 2nd thermoelectric material layer 32, the location located in the membrane 12 as the thin part 12a and connected is made into the warm junction 34, and it is made into the thick part 11a. A location that is located and connected to the base 11 is referred to as a cold junction 35.

The first thermoelectric material layer 31 and the second thermoelectric material layer 32 are formed using different materials. In the present embodiment, polysilicon is used as the first thermoelectric material layer 31, and the second Aluminum is used as the thermoelectric material layer 32. When a thermocouple 33 is constituted by a pair of the first thermoelectric material layer 31 and the second thermoelectric material layer 32 and a temperature difference occurs between the hot junction 34 and the cold junction 35, each thermoelectric is caused by the Seebeck effect. A thermoelectromotive force is generated in the pair 33. The thermopile element 30 is a thermocouple group in which a plurality of thermocouples 33 are connected in series, and the sum of electromotive forces of each thermocouple 33 is the output of the thermopile element 30. The output of the thermopile element 30 is taken out from the connection terminals 36 formed at both ends of the thermopile element 30. As shown in FIGS. 1 and 2, the hot junction 34 is formed in the thin portion 12a having a small heat capacity, and the cold junction 35 is formed in the thick portion 11a having a large heat capacity. A larger output can be obtained by increasing the temperature difference between the contact 34 and the cold junction 35.

As shown in FIG. 1 and FIG. 2, a range regulating member 20 and an infrared absorbing film 21 are formed on the membrane 12 as the thin portion 12a.

The infrared absorbing film 21 is formed at the center of the membrane 12 as the thin portion 12a so as to cover the hot junction 34. The infrared absorption film 21 can efficiently convert heat by absorbing incident infrared rays, and can increase the temperature difference between the hot junction 34 and the cold junction 35 by increasing the temperature of the hot junction 34. The infrared absorption film 21 can be applied and formed by a printing method such as ink jet printing or screen printing using a solution containing carbon black or metal oxide powder.

In the thermopile infrared sensor 1 of the present embodiment, the range restricting member 20 is formed to restrict the formation range of the infrared absorbing film 21, and is positioned between the hot junction 34 and the cold junction 35 and has a thin portion. It is formed so as to surround the center of the membrane 12 as 12a. An infrared absorption film 21 is formed in a region surrounded by the range regulating member 20. That is, the range restricting member 20 is formed between the infrared absorption film 21 and the cold junction 35.

In this embodiment, the range restricting member 20 can be formed of a silicon oxide film, a silicon nitride film, or the like, or may be formed of a resin material such as a resist material. As shown in FIG. 2, the range regulating member 20 is a wall having a convex cross section, and the range regulating member 20 is preferably formed to have a height of about 1 μm to 10 μm and a width of about 5 μm to 20 μm.

By providing the range restricting member 20, when the infrared absorbing film 21 is applied and formed, even if a solution containing carbon black or a metal oxide powder flows, the range restricting member 20 can be used to clog. That is, it is possible to prevent the solution from flowing and spreading outside the initial formation range and covering the cold junction 35. Accordingly, as shown in FIGS. 1 and 2, the hot junction 34 is formed so as to be covered with the infrared absorption film 21, and the cold junction 35 located outside the range regulating member 20 is covered with the infrared absorption film 21. It is prevented. When the thermopile infrared sensor 1 receives infrared rays, the temperature of the hot junction 34 is efficiently increased by the infrared absorbing film 21, and the temperature difference from the cold junction 35 not covered with the infrared absorbing film 21 is increased. Can do. Thereby, the sensor output of the thermopile element 30 can be increased, and the sensitivity of the thermopile infrared sensor 1 can be improved.

In particular, in the small thermopile type infrared sensor 1 mounted on a mobile device or the like, the range regulating member 20 is provided even when the distance between the hot junction 34 and the cold junction 35 is formed as small as about 100 μm to 500 μm. Thus, when the infrared absorption film 21 is applied and formed, it is possible to reliably prevent the solution containing the infrared absorption material from flowing and spreading outside the initial solution formation range. Therefore, the temperature difference between the hot junction 34 and the cold junction 35 can be widened, and the sensitivity of the thermopile infrared sensor 1 can be improved.

In addition, the range restricting member 20 is configured by a wall section having a convex cross section. In this case, the solution containing the infrared absorbing material is blocked by the convex wall section, and the range of the infrared absorbing film 21 is formed. It is possible to reliably prevent the flow toward the cold junction 35 side. However, the range restricting member 20 is not limited to such a shape, and the same effect can be obtained even if the cross-sectional shapes are different, and a configuration in which a plurality of range restricting members formed in a rod shape, an island shape, or the like is arranged. It may be.

3A is a partially enlarged plan view of a region A surrounded by a two-dot chain line in FIG. 1, and FIG. 3B is a partially enlarged view taken along the line III-III in FIG. A cross-sectional view is shown. As shown in FIG. 3A, the thermopile element 30 includes a first thermoelectric material layer 31 and a second thermoelectric material layer 32 having a planar pattern connected in a meander shape. The direction in which the first thermoelectric material layer 31 and the second thermoelectric material layer 32 of the thermopile element 30 extend by connecting the hot junction 34 and the cold junction 35 is the length direction (Y1-Y2 direction) of the thermopile element 30. The direction perpendicular to the length direction of the thermopile element 30 is defined as the width direction (X1-X2 direction) of the thermopile element 30. The length direction and the width direction of the thermopile element 30 change depending on the arrangement of the meandering plane pattern of the thermopile element 30, and for example, the meandering plane pattern arranged on the X1 side of the substrate 10 shown in FIG. In FIG. 2, the length direction of the thermopile element 30 is the X1-X2 direction, and the width direction is the Y1-Y2 direction.

As shown in FIG. 3 (a), the range regulating member 20 extends in the width direction of the thermopile element 30, and the first thermoelectric material layer 31, the second thermoelectric material layer 32, and the membrane 12 (thin wall portion 12a). Is formed on top. As shown in FIG. 3B, the range regulating member 20 is formed by filling a space between the first thermoelectric material layer 31 and the second thermoelectric material layer 32.

In particular, when miniaturization of the thermopile type infrared sensor 1 is attempted, the distance between the first thermoelectric material layer 31 and the second thermoelectric material layer 32 which are folded back and connected in a meander shape is reduced, and a narrow concave groove portion is formed. Form. When forming the infrared ray absorbing film, the solution containing the infrared ray absorbing material easily flows along the narrow concave groove. In the present embodiment, as shown in FIGS. 3A and 3B, the range regulating member 20 is formed by filling the space between the first thermoelectric material layer 31 and the second thermoelectric material layer 32. As a result, when the infrared absorption film 21 is formed, the solution containing the infrared absorption material hardly flows along the narrow concave groove. As a result, it is possible to reliably prevent the infrared absorption film 21 from being formed so as to cover the cold junction 35.

In order to further increase the temperature difference between the hot junction 34 and the cold junction 35, it is desirable to increase the amount of infrared rays absorbed by the infrared absorption film 21. As a method of increasing the infrared absorption amount of the infrared absorption film 21, increasing the volume of the infrared absorption film 21 can be considered. In the present embodiment, as shown in FIG. 2, the infrared ray absorbing film 21 is thicker than the height of the range regulating member 20 while preventing the solution containing the infrared absorbing material from flowing and spreading by the range regulating member 20. Can be formed. In the present embodiment, the infrared absorption film 21 is formed to have a curved surface protruding in the height direction (Z1 direction) from the top surface 20a of the range regulating member 20. Thereby, the volume of the infrared absorption film 21 can be increased, the amount of incident infrared rays can be increased, and the temperature of the hot junction 34 can be increased efficiently.

The graph shown in FIG. 10 shows the relationship between the temperature to be measured and the output of the thermopile type infrared sensor 1 for the thermopile type infrared sensor 1 of the present embodiment manufactured by changing the thickness of the infrared absorption film 21. As a comparative example, a thermopile type infrared sensor in which the infrared absorption film 21 is not formed is also shown. In the graph shown in FIG. 10, since the measurement is based on 25 ° C., a negative value is output at a temperature of 25 ° C. or lower, and a positive value is output at 25 ° C. or higher.

As shown in FIG. 10, in any infrared sensor, the sensor output tends to increase as the temperature of the measurement target increases. Moreover, it turns out that a bigger output is acquired as the infrared rays absorption film 21 is thickened compared with the case where the infrared rays absorption film 21 is not formed. For example, when the target temperature is 150 ° C., the thermopile infrared sensor 1 in which the film thickness of the infrared absorption film 21 is 4 μm can obtain about twice the sensor output as compared with the case where the infrared absorption film 21 is not formed. ing. Further, it was shown that about 1.2 times the sensor output can be obtained even when compared with the thermopile type infrared sensor 1 in which the film thickness of the infrared absorption film 21 is 2 μm.

Therefore, the thermopile type infrared sensor 1 of the present embodiment can reliably prevent the solution containing the infrared absorbing material from covering the cold junction 35 by the range regulating member 20 and increase the thickness of the infrared absorbing film 21. This indicates that the temperature difference between the hot junction 34 and the cold junction 35 can be increased to improve the sensor output. In the graph shown in FIG. 10, the film thickness of the infrared absorption film 21 is 2 μm and 4 μm. However, the present invention is not limited to this. It is also possible to further improve sensitivity by forming the infrared absorption film 21 thicker.

<First Modification>
In FIG. 4, the top view of the thermopile type infrared sensor 2 in the 1st modification of this embodiment is shown. FIG. 5 shows a cross-sectional view of the thermopile infrared sensor 2 cut along the line VV in FIG.

In the thermopile infrared sensor 2 of the first modification, the configurations of the base material 10 (base 11 and membrane 12) and thermopile element 30 are the same as those shown in FIGS. In the present modification, the range regulating member 20 is formed on the hot junction 34 as shown in FIG. The range restricting member 20 is formed on each hot junction 34 so as to surround the center of the membrane 12, and the infrared absorption film 21 is formed inside the range restricting member 20. As shown in FIG. 5, the infrared absorption film 21 is located closer to the center of the membrane 12 than the warm contact 34 and is formed close to the warm contact 34.

Even in such an embodiment, when the infrared absorption film 21 is formed, it is possible to prevent the solution containing the infrared absorption material from flowing and spreading outside the initial solution formation range to cover the cold junction 35. . Thereby, the infrared absorption film 21 is not formed so as to cover the cold junction 35. Further, since the infrared absorbing film 21 is formed close to the hot junction 34, when receiving infrared rays incident from the outside, the infrared absorbing film 21 absorbs the infrared rays and the temperature of the hot junction 34 rises. . Thereby, the temperature difference between the hot junction 34 and the cold junction 35 can be increased, and the sensitivity of the thermopile infrared sensor 2 can be improved.

In this modification, the distance between the range regulating member 20 and the cold junction 35 is set as compared with the case where the range regulating member 20 is formed between the hot junction 34 and the cold junction 35 as shown in FIGS. Can be larger. Therefore, the influence on the cold junction 35 when the infrared absorption film 21 absorbs infrared rays and the temperature rises can be reduced, and the temperature rise of the cold junction 35 can be suppressed. Therefore, the temperature difference between the hot junction 34 and the cold junction 35 can be increased more effectively.

<Second Modification>
In FIG. 6, the top view of the thermopile type infrared sensor 3 in the 2nd modification of this embodiment is shown. FIG. 7 is a cross-sectional view of the thermopile infrared sensor 3 cut along the line VII-VII in FIG.

The thermopile type infrared sensor 3 in the second modification differs from that shown in FIGS. 1 to 5 in that the range regulating member 20 is divided and arranged. The configurations of the base material 10 (base 10 and membrane 12) and the thermopile element 30 are the same.

As shown in FIG. 6, on the X1 side of the base material 10, a plurality of thermocouples 33 arranged adjacent to each other in the Y1-Y2 direction are used as a first thermocouple group 33a, and similarly, the X2 side of the base material 10 A plurality of thermocouples 33 arranged adjacent to each other on the Y1 side and the Y2 side are referred to as a second thermocouple group 33b, a third thermocouple group 33c, and a fourth thermocouple group 33d, respectively. In the present modification, the first range restricting member 20a extends across each thermocouple 33 of the first thermocouple group 33a in a direction (Y1-Y2 direction) intersecting the extending direction of each thermocouple 33. Is formed. Similarly, the second thermocouple group 33b, the third thermocouple group 33c, and the fourth thermocouple group 33d include the second range regulating member 20b, the third range regulating member 20c, and the fourth range, respectively. A regulating member 20d is formed.

Thus, even when the range regulating members 20a, 20b, 20c, and 20d are formed for each thermocouple group, when the infrared absorbing film 21 is formed, the solution is prevented from spreading to the cold junction 35 side, and the infrared rays are prevented. The absorption film 21 can be prevented from being formed so as to cover the cold junction 35.

As shown in the present modification, by forming the range regulating member 20 in a divided manner, the formation range of the infrared absorption film 21 can be changed variously, and the degree of design freedom can be increased. Therefore, even when the arrangement of the thermopile elements 30 and the shapes of the base 10 and the membrane 12 are different, the solution containing the infrared absorbing material flows and spreads outside the formation range of the initial solution, so that the cold junction 35 is formed. Covering can be effectively prevented. Thereby, it can prevent that the infrared rays absorption film 21 is formed so that the cold junction 35 may be covered.

<Third Modification>
In FIG. 8, the top view of the thermopile type infrared sensor 4 in the 3rd modification of this embodiment is shown. 9 shows a cross-sectional view of the thermopile infrared sensor 4 cut along the line IX-IX in FIG.

As shown in FIGS. 8 and 9, in the thermopile type infrared sensor 4 in the third modified example, the range regulating member 20 is formed so as to cover the base material 10 outside the formation range of the infrared absorption film 21. . The range regulating member 20 is formed from between the hot junction 34 and the cold junction 35 to the outer edge of the substrate 10, and the infrared absorption film 21 is formed to cover the hot junction 34. In the present modification, the cavity portion 13 of the base portion 11 is formed below the base portion 11.

Even in such an embodiment, when the infrared ray absorbing film 21 is formed by the range regulating member 20, the solution containing the infrared ray absorbing material flows and spreads outside the formation range of the initial solution. Can be prevented. Thereby, it can prevent that the infrared rays absorption film 21 is formed so that the cold junction 35 may be covered. In addition, when the range regulating member 20 is formed on a convex wall portion, the height of the range regulating member 20 may be limited depending on the aspect ratio, but in this modification, the limitation due to the aspect ratio is reduced. The height of the range restricting member 20 can be set relatively freely. Therefore, the infrared absorption film 21 can also be formed thick, and the infrared absorption amount can be improved and the sensitivity of the thermopile infrared sensor 4 can be improved.

In the thermopile type

infrared sensors

1, 2, and 3 shown in this embodiment and each modification, it is formed in a state where the infrared ray absorbing film 21 is in contact with the range regulating member 20, and the formation range of the infrared ray absorbing film 21 and the range regulating member. A case where the area surrounded by 20 is almost equal is shown. However, the present invention is not limited to such an embodiment, and it is sufficient that the range regulating member 20 is formed by preventing at least the infrared absorption film 21 from being formed so as to cover the cold junction 35.

Moreover, even when the configuration of the base 11, the membrane 12, and the like shown in the present embodiment is changed, the present invention can be applied and an equivalent effect can be achieved. For example, as shown in FIG. 9, the cavity 13 may be formed from the lower surface side of the substrate 10. Further, the same effect can be obtained even when the thermopile element 30 is configured by connecting a number of thermocouples 33 in which the first thermoelectric material layer 31 and the second thermoelectric material layer 32 are laminated via an insulating layer in series. Play.

<Method for manufacturing thermopile infrared sensor>
FIG. 11 and FIG. 12 show process diagrams of a method for manufacturing the thermopile infrared sensor 1 of the present embodiment. 11 (a), FIG. 11 (b), FIG. 12 (a), and FIG. 12 (b) each show a plan view, and each right diagram shows a line BB in FIG. 11 (a). Sectional drawing when each left figure is cut | disconnected in the location corresponding to is shown.

11A, a silicon wafer is prepared as the base 11, and an insulating film such as a silicon nitride film or a silicon oxide film is formed as a membrane 12 on the surface of the base 11. As shown in FIG. Then, a polysilicon film and an aluminum film are formed on the membrane 12 as the first thermoelectric material film 31 and the second thermoelectric material film 32. The first thermoelectric material film 31 and the second thermoelectric material film 32 are respectively formed by patterning using a photolithography method, and the first thermoelectric material film 31 and the first thermoelectric material film 31 as shown in the left diagram of FIG. A thermopile element 30 is formed in which two thermoelectric material films 32 are connected in series in a meander shape.

In the step of FIG. 11B, the formation range 21a of the infrared absorption film 21 to be formed in a later step is set. In the present embodiment, of the connection portions between the first thermoelectric material film 31 and the second thermoelectric material film 32, the connection portion formed at a position facing the inside of the substrate 10 is used as the hot junction 34, and the substrate A connecting portion formed at a position facing the outer periphery of the tenth is a cold junction 35. The formation range 21 a of the present embodiment is a region that surrounds the central portion of the membrane 12 and includes the hot junction 34 of the thermopile element 30. Then, the range regulating member 20 is formed between the formation range 21 a and the cold junction 35. The range restricting member 20 is a wall section having a convex cross section as shown in the right figure of FIG. 11B, and as shown in the left figure of FIG. And it is formed so that the hot junction 34 may be enclosed.

The range regulating member 20 is formed by forming a film using an insulating material such as silicon oxide or silicon nitride and patterning it by a photolithography method.

In the step of FIG. 12A, first, a plurality of etching holes 14 are formed at positions that do not overlap the thermopile element 30 of the membrane 12. Then, the base 11 is removed from the etching hole 14 by anisotropic etching using a strong alkaline etching solution such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH). Thereby, while forming the cavity 13 in the base 11, the membrane 12 as the thin part 12a can be formed.

In the step of FIG. 12B, the infrared absorption film 21 is formed in the formation range 21a set in the step of FIG. The infrared absorbing film 21 is formed by coating by an ink jet printing method using a solution containing an infrared absorbing material such as carbon black or a metal oxide powder.

In this manufacturing method, since the infrared absorption film 21 is formed by ink-jet printing, it can be printed on the membrane 12 as the thin portion 12a in a non-contact manner, and the membrane 12 is prevented from being destroyed in the manufacturing process. it can. The coating method is not limited to the ink jet printing method. For example, when forming by other coating methods such as a screen printing method, it is necessary to adjust the pressure applied to the membrane 12 to prevent the membrane 12 from being broken.

Also, since the solution containing the infrared absorbing material has fluidity, it tends to flow outside the initial solution formation range when applied. According to the manufacturing method of the thermopile type infrared sensor 1 of the present embodiment, since the range regulating member 20 is formed between the formation range 21a and the cold junction 35, the solution containing the flowing infrared absorbing material is the range regulating member. It is possible to prevent the cold junction 35 from being covered by the dam 20.

Further, as shown in FIG. 12B, the solution containing the infrared absorbing material can be formed higher than the height of the range regulating member 20 by utilizing the surface tension. By so doing, the infrared absorption film 21 is formed thicker with a curved surface protruding in the height direction than the top surface 20a of the range regulating member 20, so that the amount of infrared absorption is improved and heat conversion is efficiently performed. Is possible.

In the step of FIG. 12B, it is preferable to use a solution containing a thermosetting resin or an ultraviolet curable resin as a solution containing an infrared absorbing material. If it carries out like this, after apply | coating and forming the solution containing an infrared rays absorption material, heat processing or ultraviolet irradiation can be performed and resin can be hardened, and the infrared rays absorption film 21 can be formed in a short time by a simple process. The thermopile type infrared sensor 1 can be manufactured by the process as described above.

According to the manufacturing method of the thermopile type infrared sensor 1 of the present embodiment, the infrared absorption film 21 is prevented from being formed to cover the cold junction 35 and the infrared absorption film 21 is formed to cover the hot junction 34. can do. Thereby, when the infrared rays from the outside are received, the infrared absorption film 21 absorbs the infrared rays and effectively raises the temperature of the hot junction 34. Therefore, the temperature difference between the hot junction 34 and the cold junction 35 is increased, and the sensitivity of the thermopile infrared sensor 1 can be improved.

The thermopile infrared sensor 1 and the manufacturing method thereof according to the present embodiment are not limited to the configurations shown in FIGS. The present invention can also be applied to the first modification example and the second modification example shown in FIGS.

1, 2, 3, 4 Thermopile infrared sensor 10 Base material 11 Base portion 11a Thick portion 12 Membrane 12a Thin portion 13 Cavity 14 Etching hole 20 Range regulating member 20a Top surface 21 Infrared absorption film 21a Formation range 30 Thermopile element 31 1st Thermoelectric material layer 32 Second thermoelectric material layer 33 Thermocouple 34 Hot junction 35 Cold junction

Claims

A substrate, a thermopile element, and an infrared absorption film;
The thermopile element and the infrared absorbing film are formed on the base material,
A thermopile infrared sensor capable of detecting a temperature difference between a cold junction and a hot junction of the thermopile element,
A thermopile infrared sensor characterized in that a range regulating member that regulates the formation range of the infrared absorbing film is formed between the infrared absorbing film and the cold junction.
2. The thermopile type according to claim 1, wherein the range regulating member is formed between the hot junction and the cold junction, and the infrared absorption film is formed to cover the hot junction. Infrared sensor.
2. The thermopile type infrared sensor according to claim 1, wherein the range regulating member is formed on the hot junction and the infrared absorbing film is formed close to the hot junction.
The thermopile element has a planar pattern having a meander-shaped thermoelectric material,
4. The cross-sectional view in the width direction of the meander-shaped thermopile element, the range restricting member is formed by filling a space between the thermoelectric materials. The thermopile type infrared sensor described in the item.
The substrate has a thin part and a thick part formed around the thin part,
The hot junction is formed in the thin portion and the cold junction is formed in the thick portion,
The thermopile infrared sensor according to any one of claims 1 to 4, wherein the range restricting member is formed so as to surround a central portion of the thin portion.
The thermopile infrared sensor according to any one of claims 1 to 5, wherein the range regulating member is a convex wall portion.
The thermopile infrared sensor according to any one of claims 1 to 6, wherein the infrared absorbing film is formed higher than a height of the range regulating member.
A substrate, a thermopile element, and an infrared absorption film;
The thermopile element and the infrared absorbing film are formed on the base material,
A method for manufacturing a thermopile infrared sensor capable of detecting a temperature difference between a cold junction and a hot junction of the thermopile element,
(A) preparing the base material on which the thermopile element is formed, setting a formation range of the infrared absorption film, and setting a range regulating member for regulating the formation range of the infrared absorption film as the formation range Forming between the cold junctions;
And (b) applying a solution containing an infrared absorbing material to the formation range to form the infrared absorbing film, and a method for manufacturing a thermopile infrared sensor.
9. The manufacturing of a thermopile type infrared sensor according to claim 8, further comprising a step of forming a thin portion by etching the base material at a position overlapping with the hot junction after the step (a). Method.
10. The method for manufacturing a thermopile infrared sensor according to claim 9, wherein in the step (a), the range regulating member is formed so as to surround a central portion of the thin portion.
The thermopile mold according to any one of claims 8 to 10, wherein in the step (b), the solution is applied such that the solution is higher than a height of the range regulating member. Infrared sensor manufacturing method.
The method for manufacturing a thermopile infrared sensor according to any one of claims 8 to 11, wherein in the step (b), the solution is applied by an ink jet printing method.
The thermopile according to any one of claims 8 to 12, wherein, in the step (b), the infrared absorption film is formed by curing the solution by heat curing or ultraviolet curing. Type infrared sensor manufacturing method.