JP2005308551A - Thermopile type infrared sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermopile type infrared sensor capable of acquiring high-speed responsiveness coping sufficiently with an object moving at high speed, by heightening the speed of response without lowering sensor sensitivity. <P>SOLUTION: This sensor has a constitution wherein a thin film part 4 having a plan-viewed elongate shape is formed in a light receiving domain 6 on the center part of a silicon substrate 2, and a plurality of pairs of thermocouples 5 are arranged along long sides 4a, 4a of the thin film part 4 in the state where each warm junction 5h thereof is positioned on the thin film part 4 and each cold junction 5c is positioned on the silicon substrate 2 out of the light receiving domain 6, and the plurality of pairs of thermocouples 5 are connected in series. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention, for example, measures the surface temperature distribution of various objects such as human bodies, switchboards, and air conditioners, or checks the aging of buildings such as buildings and viaducts, diagnoses the deterioration of insulation, and further checks the temperature of food and clothing. The present invention relates to a thermopile type infrared sensor used for measuring a heat insulation effect. Specifically, a plurality of pairs of thermocouples are located on the thin film portion formed in the light receiving region at the center of the semiconductor substrate, their hot junctions are positioned on the thin film portion, and each cold junction is defined as the light receiving region. The present invention relates to a thermopile infrared sensor that is connected in series while being located on an external semiconductor substrate.

As a thermopile type infrared sensor of this type, as shown in the principle diagram of FIG. 7, an insulating thin film portion 21 such as SiO ₂ is formed in a square shape in a plan view at the center of the upper surface of a silicon substrate which is an example of a semiconductor substrate. A plurality of pairs of thermocouples 22 made of dissimilar metals such as aluminum and polysilicon, for example, 3 pairs per side, along each of the four sides of the square-shaped thin film portion 21 serving as the light receiving region. Thus, a total of 12 pairs are arranged in such a state that their respective hot junctions 22a are located on the thin film portion 21 and each cold junction 22b is located on a silicon substrate outside the thin film portion 21 (light receiving region). What connected the pair 22 in series is known (for example, refer patent document 1).
In addition, in patent document 1, although the thing of the form which has arrange | positioned each warm junction 22a of the several pairs of thermocouple 22 arrange | positioned on each of the four sides of the square-shaped thin film part 21 in the rectangular shape is disclosed, it becomes a light-receiving region The thin film portion 21 remains square.

JP 2001-194227 A

  As described above, in the conventional thermopile type infrared sensor in which a plurality of pairs of thermocouples 22 are arranged on each of the four sides of the square-shaped thin film portion 21, there is a tradeoff between sensor sensitivity and response speed. . That is, in the case where the thin film portion 21 is set in a square shape having a long side L of about 1 mm, for example, when measuring a 500K object (diameter 10 mm, distance to the object 100 mm), it is about 100 μV. While high sensitivity can be obtained, there is a problem that the sensor response speed at that time is as low as about 10 msec.

  In addition, in order to obtain a high-speed response that can cope with a measurement object moving at high speed, it is necessary to shorten the length of one side of the thin film portion. For example, in order to obtain a response speed of about 3 msec or more, as shown in FIG. 8, the length L1 of one side of the thin film portion 21 must be shortened to about 0.3 mm. However, in the case where the thin film portion 21 is set in a short square shape having a side length L1 of about 0.3 mm, compared with that shown in FIG. 7 in which the length L of one side is set as long as about 1 mm. Thus, not only the temperature difference between the light receiving time and the non-light receiving time, which is determined by the distance between the hot junction 22a of each thermocouple 22 and the edge of the thin film portion 21, is reduced to about 1/3, but the thin film portion Since the number of thermocouples 22 that can be juxtaposed with each other with the same pattern width is reduced to 4 pairs in total, that is, a total of 4 pairs per side, the sensor sensitivity is reduced to about 1/9, about 10 μV, compared to the one of FIG. There's a problem.

  The present invention has been made in view of the above circumstances, and the object thereof is to obtain a high-speed response sufficiently corresponding to an object moving at a high speed by increasing the response speed without reducing the sensor sensitivity. The object is to provide a thermopile infrared sensor.

  In order to achieve the above object, a thermopile infrared sensor according to the present invention includes a thin film portion formed in a light receiving region at a central portion of a semiconductor substrate, a plurality of pairs of thermocouples, and each of the hot contacts is connected to the thin film portion. In the thermopile infrared sensor provided in series with each cold junction being positioned on the semiconductor substrate outside the light receiving region, the thin film portion has two adjacent sides. Of these, one side is formed in an elongated shape longer than the other side, and a plurality of pairs of thermocouples are arranged along the long side of the elongated thin film portion.

  Here, the thin film portion may have, for example, an elongated trapezoidal shape, but it is particularly desirable that the thin film portion be formed in a rectangular shape as described in claim 2.

  According to the thermopile type infrared sensor of the present invention having the above-described characteristic configuration, the length of one side is shortened because the thermocouple is disposed along the long side of the thin film portion having an elongated shape such as a rectangle. Similar to the square shape, the temperature difference between light receiving and non-light receiving in the thin film portion is reduced, the response speed is increased, and high-speed response sufficiently corresponding to the object moving at high speed can be obtained it can. In addition, by arranging along the long side of the elongated shape, the number of thermocouples that can be juxtaposed per side with the same pattern width can be increased, so the temperature difference between when light is received and when it is not light is reduced. The sensor sensitivity that decreases due to this is compensated by the number of thermocouples installed, and as a result, a sensor sensitivity equivalent to or higher than that of the conventional one using a square-shaped thin film portion with a long side is obtained. Can do. Therefore, it is possible to provide a thermopile type infrared sensor excellent in high-speed response without deteriorating sensitivity by a very simple configuration improvement that only devise the shape of the thin film portion.

  In the thermopile type infrared sensor according to the present invention, as described in claim 3, the thin film portions are formed in a plurality of rows parallel to each other in a circular light receiving region, and along each long side of the thin film portions of the plurality of rows. Therefore, it is possible to detect an object of any shape with high sensitivity and high speed and to obtain a highly versatile infrared sensor. .

  Further, in the thermopile type infrared sensor according to the present invention, as described in claim 4, the thin film portions are formed in a plurality of rows parallel to each other in the rectangular light receiving region, and the long sides of the thin film portions of the plurality of rows are arranged. It is possible to detect an object having a generally rectangular shape or an elliptical shape like a human body with high sensitivity and high speed. A sensor suitable for human body detection can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partially cutaway perspective view of a thermopile type infrared sensor 1 according to a first embodiment of the present invention, FIG. 2 is a plan view, and FIG. 3 is a developed sectional view.

As shown in FIGS. 1 and 2, the thermopile infrared sensor 1 of the first embodiment is formed by forming an insulating film 3 such as a SiO ₂ film on the upper surface of a silicon substrate 2 which is an example of a semiconductor substrate. 2 is formed into a rectangular shape (an example of an elongated shape) having a short side of 0.3 mm and a long side of 6 mm, for example. The portion 4 is a rectangular light receiving region 6. A plurality of pairs, for example, 18 pairs, for example, a total of 36 pairs of thermocouples 5 along the long sides 4a and 4a of the rectangular thin film portion 4 forming the rectangular light receiving region 6 are connected to their hot junctions 5h. Are arranged on the thin film portion 4 and the cold junctions 5c are arranged on the silicon substrate 2 outside the light receiving region in parallel with a constant pattern width, and the thermocouples 5 are connected in series. It is configured.

  An infrared absorption film 7 is laminated on the hot junction 5h of each thermocouple 5 constituting the thermopile infrared sensor 1 as clearly shown in FIG. The thermocouple 5 is made of different metals such as aluminum 5A and polysilicon 5B, and is configured to generate a thermoelectromotive force in a direction in which the cold junction 5c is heated by the Peltier effect.

  As shown in the principle diagram of FIG. 4, the thermocouple type infrared sensor 1 of the first embodiment configured as described above has a thermocouple 5 along the long sides 4a and 4a of the thin film portion 4 having a rectangular shape. The temperature difference between the time of light reception and the time of non-light reception determined by the distance between the hot junction 5h of each thermocouple 5 and the long sides 4a and 4a that are the end sides of the thin film portion 4 is the length of one side. As shown in FIG. 8, it is smaller than the conventional one using the square thin film portion shown in FIG. 8 and has a fast response speed of about 3 msec or more, and a high-speed response sufficiently corresponding to a high-speed moving object is obtained. It is done.

  In addition, by disposing the thermocouples 5 along the long sides 4a and 4a of the rectangular thin film portion 4, the number of thermocouples 5 that can be juxtaposed per side with the same pattern width is increased to, for example, 36 pairs in total. Therefore, although the sensitivity of the sensor is lowered due to the small temperature difference between the light receiving time and the non-light receiving time, the reduced sensitivity can be compensated by the number of thermocouples 5 installed. As a result, sensor sensitivity equal to or higher than that of the conventional sensor using the square-shaped thin film portion shown in FIG. 7 having a long side is obtained. Therefore, it is possible to provide the thermopile type infrared sensor 1 having excellent high-speed response without reducing the sensitivity only by making the shape of the thin film portion 4 rectangular.

  FIG. 5 is a diagram showing the principle of the thermopile infrared sensor 1 according to the second embodiment of the present invention. The thermopile infrared sensor 1 according to the second embodiment is, for example, a rectangle having a short side of 0.3 mm and a long side of 6 mm. The diaphragm-shaped thin film portion 4 is divided into three in the longitudinal direction, and the rectangular thin film portions 41, 42, 43 divided into the three are within an elliptical light receiving region indicated by a virtual line 6 '. A plurality of pairs, for example, 10 pairs, 16 pairs, 10 pairs, and a total of 36 pairs of thermocouples 5 are formed along each long side of the three rows of thin film portions 41, 42, 43. The contacts 5h are positioned on the thin film portions 41, 42, 43, and the cold contacts 5c are positioned on the silicon substrate 2 outside the thin film portions 41, 42, 43, and are arranged in parallel with a constant pattern width. Connect each thermocouple 5 in series Those constructed Te.

  The thermocouple type infrared sensor 1 of the second embodiment configured as described above has a high response speed of about 3 msec or more without reducing the sensitivity, like the infrared sensor 1 of the first embodiment. Not only can the high-speed response sufficiently correspond to moving objects, but also the light-receiving area 6 'is a virtual oval shape, so any shape of objects can be detected with high sensitivity and high speed. It is possible to provide a highly versatile infrared sensor 1. In the second embodiment, the virtual light receiving region 6 ′ may be a perfect circle or an ellipse, and the same effect can be obtained even when such a shape is adopted.

  FIG. 6 is a principle diagram of the thermopile infrared sensor 1 of the third embodiment according to the present invention. The thermopile infrared sensor 1 of the third embodiment is, for example, a rectangle having a short side of 0.3 mm and a long side of 6 mm. The diaphragm-shaped thin film portion 4 is equally divided into two in the longitudinal direction, and the rectangular thin film portions 41 and 42 equally divided into two are divided into rectangular shapes as in the first embodiment. A plurality of pairs, for example, 18 pairs, for example, a total of 36 pairs of thermocouples 5 are formed along the long sides of the two thin film portions 41 and 42 in the light receiving region 6 '. The contact 5h is positioned on the thin film portions 41 and 42, and the cold junctions 5c are positioned on the silicon substrate 2 outside the thin film portions 41 and 42, and the thermocouple 5 Connected in series It is.

  The thermocouple type infrared sensor 1 of the third embodiment configured as described above has a high response speed of about 3 msec or more without reducing the sensitivity, like the infrared sensor 1 of the first embodiment. Since the light-receiving region 6 'is rectangular as well as high-speed response sufficiently corresponding to a moving object, an object having a generally rectangular or elliptical shape like a human body is highly sensitive. In addition, it is possible to provide an infrared sensor 1 that can be detected at a high speed and is particularly suitable for use for detecting a human body. Further, the thermocouple type infrared sensor 1 of the third embodiment can be easily configured compactly by making the ratio of the short side / long side small as compared with that of the first embodiment. In the third embodiment, the light receiving region 6 'may be square.

  In each of the above embodiments, the case where the total length of the long side of the rectangular thin film portion 4 is set to 6 mm has been shown. However, the sensor sensitivity is increased by increasing the number of thermocouples 5 in association with the length exceeding 6 mm. Of course, it may be larger.

1 is a partially cutaway perspective view of a thermopile type infrared sensor according to a first embodiment of the present invention. It is a top view of FIG. FIG. 3 is a developed sectional view. It is a principle figure of the thermopile type infrared sensor of 1st Example. It is a principle figure of the thermopile type infrared sensor of 2nd Example which concerns on this invention. It is a principle figure of the thermopile type infrared sensor of 3rd Example which concerns on this invention. It is a principle figure of the conventional thermopile type infrared sensor. It is a principle figure at the time of improving the response speed of the conventional thermopile type infrared sensor.

Explanation of symbols

1 Thermopile infrared sensor 2 Silicon substrate (semiconductor substrate)
4, 41, 42, 43 Rectangular thin film part 5 Thermocouple (thermocouple)
5h Hot junction 5c Cold junction 6, 6 'Light receiving area

Claims (4)

A plurality of pairs of thermocouples are positioned in the thin film portion formed in the light receiving region at the center of the semiconductor substrate, their hot junctions are positioned on the thin film portion, and each cold junction is a semiconductor outside the light receiving region. In the thermopile type infrared sensor provided connected in series in a state of being positioned on the substrate,
The thin film portion is formed in an elongated shape in which one of two adjacent sides is longer than the other side, and a plurality of pairs of thermocouples are disposed along the long side of the elongated thin film portion. A thermopile type infrared sensor.   The thermopile type infrared sensor according to claim 1, wherein the thin film portion is formed in a rectangular shape.   3. The thin film portion is formed by arranging a plurality of rows parallel to each other in a circular light receiving region, and a plurality of pairs of thermocouples are disposed along each long side of the plurality of rows of thin film portions. Thermopile infrared sensor. 3. The thin film portion is formed by arranging a plurality of rows in parallel in a rectangular light receiving region, and a plurality of pairs of thermocouples are arranged along each long side of the plurality of rows of thin film portions. Thermopile infrared sensor.

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