JPH07243908A - Infrared sensor, manufacture thereof, and infrared detection device - Google Patents

Abstract

PURPOSE:To provide an inexpensive infrared sensor with a low heat capacitance and high sensitivity and a manufacturing method thereof and provide a device for detecting infrared rays such as human beings in the posture of repose so as to automatically perform operation of air conditioner, movement of louver, and opening/closing of door. CONSTITUTION:An infrared-ray sensor in which an insulation film 2 having an infrared detection element forming part is provided on a board 6, an infrared detection element 1 is provided on the element molding part of the insulation film 2, and a cavity part 5 is formed on the lower side of the element forming part of the insulation film 2, is provided with a thin film 7 consisting of a material having good wettability at least against board etching liquid and/or a reflection plate which can easily recognize reflection light on the cavity part side of the insulation film of the element forming part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor, a method for manufacturing the same, and an infrared detector. More specifically, when the air conditioner is turned on and off, the louver of the air conditioner is moved, the door is opened and closed, etc., the pyroelectric property of detecting infrared rays of a person, the element property due to heat such as the resistance change due to temperature and the thermoelectromotive force The present invention relates to an infrared sensor that utilizes changes in temperature, its manufacturing method, and an infrared detection device.

[0002]

2. Description of the Related Art Conventionally, as a sensor capable of detecting infrared rays of a person, one using pyroelectric pyroelectric ceramics, thermoelectromotive force type thermopile, resistor type bolometer and the like have been used.

Among these, a pyroelectric sensor, which has a relatively high sensitivity and is inexpensive, is advantageously used. The pyroelectric infrared sensor is formed by providing electrodes on both front and back surfaces of a pyroelectric ceramic or single crystal. The pyroelectric infrared sensor is composed of a thin film and has a small heat capacity in order to increase its detection sensitivity. For example, in the pyroelectric sensor disclosed in JP-A-60-180180, an element is formed on a magnesium oxide substrate,
After that, the back surface of the substrate is etched to reduce the heat capacity. Further, JP-A 1-136035 and JP-A 4-158583 disclose a structure in which a groove is formed in a silicon substrate, a spacer is inserted to smooth the groove, and a pyroelectric sensing element is formed thereon. ing. Further, Japanese Patent Laid-Open No. 3-287022 discloses a method of forming a resist portion in a predetermined range on a substrate, forming a support film thereon, forming a space, and then forming a sensing element thereon. Has been done.

On the other hand, a pyroelectric sensor can detect a moving object or an object whose temperature changes, but since it measures the change in polarization due to temperature, it cannot detect a stationary object or an object with no temperature change. By the way, a chopper is needed. Such an infrared detecting device is disclosed in, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 65328, there is known a method of providing a two-dimensional image pickup apparatus including a one-dimensional pyroelectric infrared detecting element, an optical chopper and an optical scanner.

[0005]

The pyroelectric type sensor described above, in which the element is formed on the magnesium oxide substrate, has a drawback that the magnesium oxide substrate lacks stability. Further, it is difficult to embed a spacer only in a groove when forming a groove on a silicon substrate, and it is necessary to polish it in order to form a flat surface with the substrate, but polishing tends to contaminate the silicon substrate. There's a problem. Furthermore, it is difficult to form the sensing element on the supporting film in which the space is formed, and conversely, if it is attempted to form the sensing element before removing the photoresist, the pyroelectric sensor produces 400 ° C as the crystal generation temperature. Since it is necessary to set the above, it is impossible to form the sensing element because the photoresist is deformed and deteriorated. Since other thermo-electromotive force type infrared detecting elements also have low sensitivity, it is necessary to further reduce the heat capacity.

Further, as described above, an optical chopper must be provided in order to detect infrared rays in a stationary state by the pyroelectric sensor, but in the above method, a disk is used as an optical chopper to rotate the disk. Therefore, when applied to a single-row array of elements, the beginning and end of the array are located outside the chop, the middle is located inside, and the peripheral speeds are different near and far from the central axis of the blade. If the device is large, it is necessary to correct the signal. An object of the present invention is to solve the above problems and to provide an infrared sensor with a high sensitivity, in which a cavity is surely formed under the element formation portion, the heat capacity is small.

Another object of the present invention is to provide a method of manufacturing an infrared sensor which can easily and surely form a cavity below the element forming portion in order to reduce the heat capacity of the infrared detecting element. .

Still another object of the present invention is to provide an infrared detecting device capable of efficiently detecting infrared rays of a stationary object even when the pyroelectric sensor is used.

[0009]

In an infrared sensor of the present invention, an insulating coating having an infrared detecting element forming portion is provided on a substrate, and the infrared detecting element is provided on the element forming portion of the insulating coating. An infrared sensor in which a cavity is formed below the element forming portion of the coating, the thin film being made of a material having good wettability to at least the etching liquid of the substrate on the cavity side of the insulating coating of the element forming portion. Is provided.

The infrared sensing element is a pyroelectric sensing element, and a pair of comb-shaped electrodes formed so that the comb teeth are staggered on the insulating film, and provided on at least one surface side of the comb-shaped electrodes. It is possible to make the pyroelectric film thin, and since the lateral polarization is used, there is no problem even if a few pinholes are formed in the sensing element film, and a pair of electrodes is formed. Is also preferable because it can be formed in one step.

The method of manufacturing the infrared sensor of the present invention is
(A) A thin film made of a material having a high wettability with an etching solution of the substrate or a material easily soluble in the etching solution is provided in a region of the substrate where an element forming portion is provided, and (b) on the thin film and the substrate. An insulating coating is provided on the surface, and (c) an infrared detecting element is formed on the element forming portion of the insulating coating.
(D) A window portion for etching is provided near the element forming portion of the insulating coating, and (e) the substrate under the element forming portion is etched from the etching window portion to form a cavity. Characterize.

In the step of providing the insulating coating, a silicon oxide film or a silicon nitride film is previously provided at room temperature by a sputtering method and then heat-treated at 600 to 1000 ° C., or a CVD method under heating at 600 to 1000 ° C., A step of providing a silicon oxide film or a silicon nitride film by a sputtering method or oxidation is preferable because the resistance to an alkaline etching solution becomes strong.

Further, in the infrared detection device of the present invention, a plurality of pyroelectric infrared sensors are arranged in an array, and a cylindrical shutter having a plurality of holes on the front surface of the infrared sensor, the holes rotating along the arrangement direction of the infrared sensors. Is provided.

[0014]

According to the infrared sensor and the manufacturing method thereof of the present invention, a thin film having good wettability to the etching liquid of the substrate or a thin film soluble to the etching liquid is provided on the substrate side of the element forming portion of the insulating film. Since the etching solution is provided, the etching solution permeates the lower side of the element forming portion through the thin film when the substrate is etched through the window of the insulating film, and the cavity is easily formed only under the element forming portion. You can Therefore, the insulating coating can be formed very thin, and the heat capacity of the infrared sensor can be made very small.

Further, according to the infrared detecting device of the present invention,
Infrared sensors arranged in an array are equipped with a rotating body with multiple holes in front of them, so it is possible to continuously detect infrared rays from a stationary person while using a pyroelectric sensor that has high sensitivity and is inexpensive. You can

[0016]

1 is a part of an explanatory plan view showing the basic concept of an embodiment of an infrared sensor of the present invention, and FIG. 2 is a sectional view taken along the line AA. 1 and 2, reference numeral 1 denotes an infrared detecting element, which is formed on the element forming portion 2a of the insulating coating 2 provided on the substrate 6. Reference numeral 3 denotes a window portion provided in the insulating coating 2 for forming the cavity 5 in the substrate 6 below the element forming portion 2a, and the cavity 5 is formed by etching the substrate 6 from the window portion 3. There is. The substrate 6 remaining around the cavity 5 forms a lattice portion 6a, and the element forming portion 2
a is connected to the insulating coating 2 on the lattice portion 6a via the bridge portion 2b and held. As a result, the infrared detecting element 1 is held in a suspended state on the cavity 5 by the thin insulating coating 2 supported by the bridge portion 2b, and the heat capacity is reduced. The present invention is characterized in that the thin film 7 having good wettability with the etching liquid for the substrate 6 is provided on the lower side (back surface side) of the element forming portion 2a. It is preferable that a metal film or a colorant film is provided between the thin film 7 and the element forming portion, because it is easy to see for alignment in a later step. That is, as described in detail in the method of manufacturing the infrared sensor of this embodiment, the thin film 7 having good wettability with the etching liquid is provided only between the element forming portion 2a and the insulating coating 2 and the substrate 6. When the substrate 6 is etched through the window portion 3, the etching liquid easily penetrates between the thin film 7 and the substrate 6, so that only the lower side of the element forming portion 2a is etched and the cavity 5
Can be formed in a short time.

As the infrared detecting element 1, a pyroelectric type detecting element for detecting the polarization of the pyroelectric material with both electrodes, a resistor type detecting element for detecting the resistance change due to the temperature of the resistor, a thermopile caused by the temperature of a thermopile or the like. The present invention can be commonly applied to a thermoelectromotive force type detection element that detects a change in electric power and a detection element that can improve detection sensitivity by reducing a heat capacity, such as a capacitor type detection element that is driven by an alternating current. Among them, the pyroelectric detection element is particularly preferable because it has high sensitivity and low cost by reducing the heat capacity.

Pyroelectric materials used for the pyroelectric sensing element include PbTiO ₃ , LiTaO ₃ , and Pb (Ti _1-x Zr _x ).
O ₃ or the like is used, and a pyroelectric film having a perovskite structure can be obtained by heating the substrate to about 500 ° C. using these as a sputtering target and performing sputtering. As the pyroelectric material, Sr _1-x Ba _x Nb ₂ O _{5 and the} like can obtain high pyroelectricity in addition to the perovskite structure. Further, as the lower electrode provided under the pyroelectric film, platinum, gold, etc. can be preferably used because they have high resistance to the treatment in each step. However, since platinum and gold have low adhesion to the pyroelectric film or insulating coating, it is possible to interpose a chromium metal, titanium metal, titanium nitride film, or the like between the insulating coating or pyroelectric film and the electrode. It is preferable from the viewpoint of the adhesiveness of the electrodes. Further, as the upper electrode, it is preferable to use a conductive film such as nichrome, silicon carbide or carbon which has a high infrared absorption property, since infrared rays can be efficiently absorbed.

The substrate 6 may be any one that can be chemically anisotropically etched so that the cavity 5 can be formed below the element forming portion 2a.
A silicon substrate having a (0) plane or a (110) plane is particularly preferable because it is easy to form a recess only under the element formation portion 2a and the manufacturing process such as formation of the insulating coating 2 is easy. .

The insulating coating 2 can be formed on the substrate to a thickness of about 0.05 to 1 μm, and it may be any film as long as it is electrically insulating, has poor heat conduction, and has mechanical strength. A film, a silicon nitride film or a mixed film thereof is particularly preferable from the viewpoints that the above-mentioned various properties are obtained and the film is easily formed. However, silicon oxide is etched by a potassium hydroxide aqueous solution which is an etching solution for the substrate, the window 3 becomes large, and silicon nitride has an effect of preventing the gap from becoming large. Therefore, when an aqueous solution of potassium hydroxide is used as the etching solution, it is preferable to use a silicon nitride film. Moreover, since a part of the insulating coating 2 is the element forming portion 2a, it is more preferable that the insulating coating 2 has a thickness of 0.
It is preferably formed to a thickness of about 05 to 0.5 μm.

The element forming portion 2a is preferably isolated from the surroundings in order to reduce the escape of heat and the heat capacity as much as possible, but for example, two elements are orthogonal to each other by utilizing the crystallographic direction of the silicon substrate used as the substrate. Inside the quadrangle surrounded by the parallel lines, right-angled triangular window portions 3 are provided at the four corners of the quadrangle for etching the silicon substrate, and are formed in the quadrangle shape. It is preferable to have a shape in which the portion 6a and the bridge portion 2b are connected and held so that the shape can be facilitated and the heat capacity can be reduced.

As the thin film having good wettability with respect to the etching liquid of the substrate 6 described above, the etching liquid from the window 3 is likely to come into contact with the substrate 6 below the element forming portion 2a, and the element forming portion 2a
This is to enable the etching of the substrate 6 immediately below to be completed quickly and surely, and when a silicon substrate is used as the substrate 6, a zinc oxide film, an amorphous aluminum oxide (AlOx) film, a borosilicate glass film, a chip. An aluminum nitride (AlNx) film or the like can be used. Alternatively, CuO, MgO, or the like, which is easily dissolved in an alkaline solution used as an etching solution for silicon, may be used. In this case, this thin film does not remain in the infrared sensor as a product. This thin film facilitates the permeation of the etching solution into the substrate surface under the element forming portion 2a, and is 0.01 to 0.05 μm.
It is enough if a certain degree is provided. This is because if the thickness is too thick, the height of the element forming portion 2a becomes large and the electrode film or the sensing element film is easily cut at the end portion, and if it is too thin, the purpose of facilitating penetration of the etching solution cannot be achieved.

Thin film 7 having good wettability with etching solution
, The thin film 7 has a thickness of 0.01 to 0.05 μm as described above.
Since the thickness is very thin, about m, there is little color difference, and it becomes very difficult to align the mask used in the subsequent process. Therefore, it is preferable to interpose a reflective film 8 such as a metal film or a colorant film that easily recognizes the reflected light between the thin film 7 and the element forming portion 2a of the insulating coating 2. By providing the reflective film 8,
It becomes easier to observe the reflected light. This reflective film 8 is also 0.01-0.05μ
If it is provided with a thickness of about m, it contributes to the mask alignment sufficiently, and conversely, if it is thicker than this, the heat capacity of the element forming portion becomes too large and the sensitivity of the sensor decreases, which is not preferable. If the electrode of the infrared detecting element 1 is not formed on the entire surface of the element forming portion 2, a part of the infrared rays incident on the detecting element 1 part will pass through between the electrodes and escape to the cavity 5. However, when a metal film is provided as the reflective film 8, the metal film reflects the light, so that the incident heat can be efficiently absorbed. As such a metal film, for example, Cr, Ni, Mo, W, Nb, Ta, Pt, Au or the like can be used. These metal films are preferable because they can be easily formed by sputtering and sufficient reflection can be obtained. When a colorant film is used as the reflective film instead of the metal film, MnO ₂ , Cr ₂
If O ₃ , Fe ₂ O ₃ , CoO, C or the like is used, the reflected light can be easily recognized and the mask can be easily aligned.

A preferred embodiment of the present invention is as follows.

In a preferred embodiment of the infrared sensor of the present invention, an insulating coating having an infrared detecting element forming portion is provided on a substrate, the infrared detecting element is provided on the element forming portion of the insulating coating, and the insulating coating of the insulating coating is provided. An infrared sensor in which a cavity is formed below the element forming portion, wherein a reflection film that easily recognizes reflected light is provided at least on the cavity side of the insulating coating of the element forming portion. .

Even if a thin film having a good wettability with respect to the etching liquid or a thin film easily dissolved with the etching liquid is provided by providing the reflection film on the lower side of the element forming portion, which allows the reflected light to be easily recognized, The mask alignment is easy, and you can get a precise infrared sensor.

Since the reflection film is a metal film, the reflected light is clear and mask alignment is easy, and when an electrode having a gap such as a comb-shaped electrode is used as the detection element, the infrared rays transmitted through the gap are detected. It is preferable because it can be reflected and infrared rays can be effectively used.

As the metal film, Al, Cr, Ni,
It is preferable to use at least one of Nb, Ta, Au, and Pt from the viewpoint of easy film formation and high reflection efficiency.

Further, even if the reflection film is a colorant film, it is preferable that the reflected light can be easily recognized when the mask is aligned and accurate patterning can be performed.

It is preferable that a thin film made of a material having a good wettability with the etching solution for the substrate is further provided on the cavity side of the reflective film, because the substrate under the element forming portion can be etched in a short time. .

It is often used as an etching solution for a substrate that the film having good wettability with the etching solution is at least one of a zinc oxide film, an amorphous aluminum oxide film, a borosilicate glass film or an aluminum nitride film. It is preferable because it has good wettability with an alkaline solution and can accelerate the etching action.

Since the substrate is a silicon substrate having a (100) plane or a (110) plane, it is possible to form a cavity only under the element formation portion by anisotropic etching. preferable.

Further, the insulating coating is a silicon oxide film, a silicon nitride film or a zirconium oxide film,
It is preferable because it has high resistance to the etching liquid of the substrate and the film formation is easy.

Further, the element forming portion is formed in a quadrangular shape, and the four corners of the quadrangular element forming portion are held by bridge portions connected to the lattice portion of the substrate remaining around the cavity. It is preferable that the heat capacity of the element forming portion can be reduced and the sensitivity of the infrared sensor can be improved.

It is preferable that the infrared detecting element is a pyroelectric type detecting element because it has high sensitivity and can be formed at low cost.

When the infrared detection element is a pyroelectric detection element, a pair of comb-shaped electrodes formed so that the comb teeth are staggered on the insulating coating, and at least one surface side of the comb-shaped electrodes are provided. When a pyroelectric film is used as the detection element film, the pyroelectric film has a thickness of 0.2 to 5 μm so that the polarization effect can be completely achieved with a small heat capacity. Is preferred.

The sensing element film may be formed of a resistor.

A sensing element composed of the resistor comprises a pair of comb-shaped electrodes formed on the insulating coating so that the comb teeth are staggered, and a resistor film provided on at least one surface side of the comb-shaped electrodes. It is preferable that even if it is composed of, it is not necessary to perform heat treatment for obtaining crystallinity.

Since the resistor film is made of at least one of a manganese oxide-cobalt oxide-nickel oxide thermistor resistor, silicon carbide or a carbon resistor, it is easy to form and can detect even a small change in infrared rays. preferable.

The sensing element is preferably a thermoelectromotive force type sensing element or a capacitor type sensing element because it can measure the absolute temperature.

A method of manufacturing the infrared sensor of the present invention (a)
A thin film made of a material having a high wettability to an etching solution for the substrate is provided on an element forming portion on the substrate, (b) an insulating coating is provided on the thin film and on the surface of the substrate, and (c) an element of the insulating coating is formed. An infrared detecting element is formed on the portion, and (d) an etching window is provided near the element forming portion of the insulating coating,
(E) In a manufacturing method including a step of forming a cavity by etching the substrate below the element forming portion from the etching window portion, reflected light is emitted between the step (a) and the step (b). It is preferable to further include a step of providing a reflection film that can be easily recognized, because it becomes easy to perform mask alignment accurately in a later step.

A silicon substrate having a (100) plane or a (110) plane is used as the substrate, and the element formation region is formed on the plane (01
It is preferable to form a line parallel to the (0) plane and the (001) plane or a line parallel to the (111) plane because the boundary line between the etched portion and the non-etched portion can be a straight line.

A film made of an electrode and / or a sensing element material is formed on the element formation portion on the substrate surface by a lift-off method, and after forming the film, a burr remaining around the film is wiped with a cloth. The removal by wiping is preferable because the electrodes and the film of the sensing element are not cut at the boundary line.

In the infrared detecting element provided with the cylindrical shutter having a plurality of holes for rotational movement on the front surface of the array-type pyroelectric infrared sensor of the present invention, the infrared sensor has at least 2 parts including at least a peripheral surface of a truncated cone. If a plurality of cylindrical shutters are arranged and the cylindrical shutter also has at least two surfaces along the surface on which the infrared sensor is arranged, a small sensor can accurately detect infrared rays of a human still in a wide range. However, it is preferable because the position can be specified.

Next, the method for manufacturing the infrared sensor and the infrared detecting device of the present invention will be described with reference to specific examples.

[Embodiment 1] FIGS. 3 to 4 are views showing a manufacturing process of a pyroelectric infrared sensor which is an embodiment of the infrared sensor of the present invention, and are a cross sectional explanatory view and a plan explanatory view, respectively.

First, as shown in FIGS. 3 (a) and 3 (b),
For example, a thin film 7 made of a material having good wettability with an etching solution or a material easily dissolved in an etching solution in the element forming part of a substrate 6 made of an n-type silicon substrate having a (100) surface or a (110) surface A reflective film 8 made of a metal film or a colorant film is provided so that reflected light can be easily recognized. Specifically, for example, a photoresist is applied to the entire surface of the substrate 6, and the photoresist in the element forming portion is removed in a quadrangle surrounded by a plurality of two orthogonal lines parallel to the (111) plane. , A photoresist layer 9 is provided on a portion other than the element formation portion, and then the sputtering method or the CV method is used.
By the D method or the like, a thin film 7 made of a material having a good wettability, such as a zinc oxide, and a metal film made of, for example, chromium, are provided in an etching solution for a silicon substrate, for example, a KOH aqueous solution, and each of them is provided with a thickness of 0.01 to 0.05 μm. After that, the photoresist is dissolved and removed with acetone or the like, so that the thin film 7 and the reflection film 8 other than the element formation portion are removed (lift-off).

Next, as shown in FIG. 3C, the insulating coating 2 is provided on the entire surfaces of the reflective film 8 and the substrate 6. Specifically, it is formed by depositing silicon oxide or silicon nitride by the well-known CVD method or sputtering method.

In this case, after providing a silicon oxide film or a silicon nitride film by a sputtering method at around room temperature, the whole substrate is heat-treated under a nitrogen atmosphere of 600 to 1000 ° C., or at 600 to 1000 ° C. CVD method under heating,
It is preferable to provide a silicon oxide film or a silicon nitride film by a sputtering method or oxidation so that the resistance to alkali becomes strong and the substrate is not damaged during etching of the substrate.

Next, an infrared detecting element is formed on the element forming portion 2a of the insulating coating 2. Specifically, FIG. 3D to FIG.
As shown in (e), the lower electrode 11, the pyroelectric film 12, and the upper electrode 13 are sequentially formed. For example, a photoresist is applied to the entire surface, the pattern of the lower electrode 11 part and the wiring part is exposed, a metal film of Cr, Ti or the like is provided by sputtering, Pt or Au is provided thereon, and then the photoresist is applied. By removing, the metal film on the photoresist layer can also be removed (lifted off) at the same time, and the lower electrode 11 and its wiring portion can be formed (see FIG. 3D). Next, using a metal mask having a hole corresponding to the formation portion of the pyroelectric film 12, heating to about 500 ° C. and depositing a pyroelectric material such as BaTiO ₃ by sputtering, and removing the mask. Thereby, the pyroelectric film can be provided only on the lower electrode 11. Further, the upper electrode 13 and its wiring (not shown) can be formed in a predetermined shape by the lift-off method like the lower electrode. In FIG. 4 (e), the wiring from the upper electrode 13 ends on the infrared detection element film, but when a metal mask is used, the end of the film generally does not show a right-angled cut at the end of the mask and is oblique. Since the slope is formed, the wiring is not broken even if it is further extended and reaches the insulating film.

Next, an etching window is provided near the element forming portion of the insulating coating. Specifically, as shown in the plan view of FIG. 4 (f), a photoresist 25 is applied to the entire surface of the substrate 6 and exposed to remove the photoresist only in the window portion 3 to remove hydrofluoric acid and fluorine. The silicon of the substrate 6 is exposed by etching with a mixed aqueous solution of ammonium chloride. After that, the photoresist is removed.

Next, the substrate under the element forming portion is etched through the etching window to form a cavity.
Specifically, by immersing it in an etching solution such as an aqueous solution of potassium hydroxide or an organic alkali and bringing it into contact with the etching solution through the window portion 3, the etching solution is passed through the thin film 7 having good wettability to form the element forming portion 2a. Penetrating to the lower side, silicon is etched along the crystal plane of the silicon substrate,
As shown in the cross-sectional explanatory view of FIG. 4G, the cavity 5 having an inverted triangular cross section is easily formed.

The main point of the above method is that the electrode pattern, the thin film having good wettability with the etching solution, and the pyroelectric film are lift-off methods (after the pattern is exposed on the photoresist and after development, the metal film including the photoresist is formed). When the photoresist is removed after the formation, the metal film on the photoresist is also removed) to form a necessary portion. The advantage of the lift-off method is that it can be treated with a less toxic solvent such as acetone as a solvent for removing the photoresist layer.

In the lift-off method, it is effective to use an ultrasonic cleaner when removing the photoresist layer in a solvent, but after the photoresist layer is removed, burrs remain around the pattern. To do. Therefore, in order to remove the burrs, it is preferable to immerse the solvent in a soft cloth and wipe the surface of the pattern several times lightly.

[Embodiment 2] FIG. 5 is an explanatory view of a detecting element portion of another embodiment of the pyroelectric type of the infrared sensor of the present invention.
Is a plan view, and (b) is a cross-sectional view. In this embodiment, electrodes provided with a pyroelectric body sandwiched therebetween are provided as comb-shaped electrodes 14 and 15 on one surface of the pyroelectric film 10 so as to alternate with each other. The arrow 17 in FIG. 5 indicates the polarization direction.

When the infrared sensor is a pyroelectric material, ceramics having a thickness of about 100 μm have been used so far. Therefore, electrodes have been formed above and below the electrode and polarized. However, the thickness is several μ
With a thin film of about m, even if a voltage is applied in a direction parallel to the film for polarization, the film can be polarized in the thickness direction as shown by arrow 17. Further, the vibration of light is a polarization vibration in a solid, which coincides with the polarization direction. In this case, there is an advantage that even if there are some pinholes in the pyroelectric film, it can be detected as compared with the case where electrodes are formed above and below the pyroelectric film. In FIG. 5A, the electrode is formed on the upper part of the film, but it is more reliable if it is formed on the lower part of the sensing element because it is less likely to be affected by the funnel. Further, when the electrode is formed only on the lower portion, there is an advantage that it is not necessary to lower the wiring from the upper portion of the pyroelectric film having a thickness to a flat surface, and there is no fear of cutting at the end portion of the wiring.

[Embodiment 3] FIGS. 6 to 7 are cross-sectional explanatory views and plan explanatory views showing a method of manufacturing an infrared sensor according to another embodiment of the present invention in which the sensing element is a resistor.
111 is one of the comb-shaped electrodes, which are alternately opposite poles, 131
Is the other electrode, and 121 is a resistor film.

First, FIGS. 6A to 6C show FIGS.
Similar to the description of (c) in Example 1, the thin film 7 and the reflective film 8 having good wettability with the etching solution are provided on the element formation portion on the substrate 6, and the insulating coating 2 is provided on the entire surface of the substrate 6.

Then, both electrodes 111 and 131 are provided by the lift-off method as in the first embodiment. In this embodiment, both electrodes are formed as comb-shaped electrodes on the same surface as in the pyroelectric type of the second embodiment, and are provided so as to be staggered. Then, a resistor film made of, for example, a manganese oxide-cobalt oxide-nickel oxide based thermistor resistor is formed on the element forming portion 2a.
This resistor film is also formed by providing a photoresist layer on the entire surface of the substrate 6 similarly to the pyroelectric film described above, and the sensor forming portion 2 is formed.
After removing the photoresist layer only on a and forming the resistor film 121 by sputtering or the like, the photoresist layer on the photoresist layer is also removed by removing the photoresist layer with, for example, an acetone solvent. The resistor film can be formed only on the element forming portion. The resistance type infrared sensor detects the presence of infrared rays by detecting the change in resistance that changes due to the irradiation of infrared rays.Even with such a structure, the resistance between the electrodes 111 and 131 is the temperature change of the resistance film 121. It can be accurately detected because it changes depending on. Moreover, since it is not necessary to provide an electrode on the infrared irradiation side, it is possible to efficiently detect the irradiated infrared rays.

Next, as shown in FIG. 7F, the window portion 3 is provided as in the first embodiment. Then, as shown in FIG. 7 (g), an etching solution is injected from the window 3 to anisotropically etch the silicon substrate to form the cavity 5 as in the first embodiment.

In this embodiment as well, the thin film 7 having good wettability with the etching solution is a means for etching the silicon substrate to facilitate formation of a cavity under the element forming portion.
If a metal film is used as the reflection film 8, it is also effective for reflecting infrared rays escaping from the gap of the electrode. However, in this case, if the thickness of the insulating coating 2 is small and the resistance is smaller than that of the resistor film 121, the current is exclusively applied to the insulating coating 2.
Be careful because it flows inside.

As the resistor sensing element, in addition to the manganese oxide-cobalt oxide-nickel oxide type thermistor resistor thin film, silicon carbide, carbon type resistor film or the like can be used. According to the present invention, since the heat capacity of the detecting element can be reduced, even a detecting element using a resistor having a poor sensitivity can be put to practical use as an infrared sensor.
In the case of the resistor film, the sensing element film may be amorphous, so that it can be formed at room temperature, and the formation region of the sensor film can be limited by the lift-off method of photoresist.

[Embodiment 4] FIG. 8 shows an embodiment in which a shutter is formed in an infrared sensor (detection element) array for detecting a human. Reference numeral 18 is a detection element array, 19 is a drum, and a plurality of holes (pin holes) 20 are formed in the drum 19. Reference numeral 21 is a shaft for rotating or reciprocating the drum. In a pyroelectric infrared sensor (detection element), when infrared rays of a person are detected, the temperature of the pyroelectric material rises and spontaneous polarization changes, but electric charges that cannot cope with the change are detected. Therefore, the pyroelectric infrared sensor (detection element) can detect a moving person, but in order to detect a stationary person, a shutter must be attached and the temperature must be restored. Therefore, usually, a rotating body having a slit is placed to chop the light. However, in the case of a single element, this is fine, but in the case of a rotating body, the sensor elements arranged in a row have ends that pass through the outer side, the middle pass through the inner side, and the outer and inner elements have different peripheral velocities. The irradiation time will be different. The example shown in FIG. 8 is an invention made to solve this. In Figure 8, holes (pin holes)
When the 20 moves from right to left due to the rotation of the drum 19, the upper stage of the element array is detected from right to left, and when the upper stage ends,
Immediately, the next-stage hole (pinhole) 20 is opened to detect the next-stage element array from right to left.

According to the present embodiment, since chopping is performed by the drum, there is an effect that the peripheral speed is the same regardless of the position of the sensor element and the position can be accurately detected.

[Embodiment 5] FIG. 9 shows an example in which infrared sensors (detection elements) for detecting humans are three-dimensionally arranged, and a rotatable three-dimensional structure having a hole (pinhole) in front of the infrared sensor. It is an infrared detection device in which a drum having a different shape is arranged. Reference numeral 22 is an array of infrared sensors (detection elements), and 23 is a drum having a two-tiered hole. In this example, eight detection elements are arranged in a semicircular shape, and eight detection elements are arranged in a further downward direction. By doing so, it is possible to detect a person from left to right and forward and backward, and it is possible to stereoscopically detect the position of a person or the like. In this example, although the holes 24 of the drum 23 are slightly increased, basically, one hole is used to scan the upper stage, and the next lower hole is used to scan the lower stage.
This method can detect human stationary objects, but it will malfunction if there is a higher temperature part than humans,
It is necessary to detect the difference by storing the background temperature in advance.

[0066]

As described above, according to the present invention, since the lower portion of the sensor is hollowed out, a thin film having good wettability with an etching solution or a thin film soluble with an etching solution is interposed between the insulating film and the substrate. Therefore, the substrate is easily etched. As a result, it is possible to easily and surely form the cavity below the element formation portion, and to obtain a highly sensitive infrared sensor having a small heat capacity.

Further, since the etching can be carried out easily, the number of manufacturing steps can be shortened and an inexpensive infrared sensor can be obtained.

Furthermore, by providing an infrared detection device in which the array of detection elements is scanned using a perforated drum, there is an advantage that a pyroelectric infrared sensor can accurately detect even a stationary object and the position thereof. is there.

[Preferred Embodiment of the Present Invention] (1) An insulating coating having an infrared detecting element forming portion is provided on a substrate, and an infrared detecting element is provided on the element forming portion of the insulating coating. An infrared sensor in which a cavity is formed below the element formation portion, wherein an infrared sensor is provided in which at least a reflection film for easily recognizing reflected light is provided on the cavity side of the insulating coating of the element formation portion.

(2) The infrared sensor according to (1), wherein the reflective film is a metal film.

(3) The metal film is Al, Cr, Ni, M
The infrared sensor according to (2), which comprises at least one of o, Nb, and Pt.

(4) The reflective film is a colorant film (1)
Infrared sensor described.

(5) The infrared sensor according to (1), wherein a thin film made of a material having a high wettability with the etching solution for the substrate is further provided on the cavity side of the reflective film.

(6) The infrared sensor according to claim 1, wherein the film having good wettability with the etching solution comprises an amorphous aluminum oxide film or an aluminum nitride film (5).

(7) The substrate is a (100) surface or a (110)
A silicon substrate having a plane crystal face (1),
(2), (3), (4), (5), (6) or the infrared sensor according to claim 1.

(8) The insulating coating is a silicon oxide film (1), (2), (3), (4), (5), (6),
(7) or the infrared sensor according to claim 1.

(9) The insulating coating is a silicon nitride film or a zirconium oxide film (1), (2), (3),
(4), (5), (6), (7) or the infrared sensor according to claim 1.

(10) The element forming portion is formed in a quadrangular shape, and four corners of the quadrangular element forming portion are held by bridge portions connected to the lattice portion of the substrate remaining around the cavity. (1), (2), (3), (4),
(5), (6), (7), (8), (9) or the infrared sensor according to claim 1.

(11) The infrared detecting element is a pyroelectric type detecting element (1), (2), (3), (4), (5),
(6), (7), (8), (9), (10) or the infrared sensor according to claim 1.

(12) The thickness of the pyroelectric film is 0.2 to 5 μm
The infrared sensor according to claim 2, wherein

(13) The infrared detecting element is a detecting element composed of a resistor (1), (2), (3), (4),
(5), (6), (7), (8), (9), (10) or the infrared sensor according to claim 1.

(14) A sensing element comprising the resistor is provided on a pair of comb-shaped electrodes formed on the insulating film so that the comb teeth are staggered, and on at least one surface side of the comb-shaped electrodes. The infrared sensor according to (13), which comprises a resistor film.

(15) The resistor film is made of at least one of a manganese oxide-cobalt oxide-nickel oxide based thermistor resistor, silicon carbide or a carbon based resistor (1
3) Infrared sensor described.

(16) The infrared detection element is a thermoelectromotive force type detection element (1), (2), (3), (4),
(5), (6), (7), (8) or the infrared sensor according to claim 1.

(17) The infrared detecting element is a condenser type detecting element (1), (2), (3), (4),
(5), (6), (7), (8), (9), (10) or the infrared sensor according to claim 1.

(18) The method for manufacturing an infrared sensor according to claim 3, further comprising a step of providing a reflective film which makes it easy to recognize reflected light between the steps (a) and (b) of claim 3.

(19) As the substrate, a (100) plane or a (1) plane is used.
A silicon substrate of 10) plane is used, and the element formation region is formed by lines parallel to (010) plane and (001) plane or (111) plane on the plane.
4. The method for producing an infrared sensor according to claim 18, wherein the infrared sensor is formed by a line parallel to the surface.

(20) A film made of an electrode and / or a sensing element material is formed on the element forming portion on the substrate surface by a lift-off method, and after the film is formed, the film remains around the film. The method for producing an infrared sensor according to claim 3, characterized in that the burrs are removed by wiping with a cloth (18), (19), (20) or.

(21) A plurality of the pyroelectric infrared sensors are arranged on at least two surfaces including at least the peripheral surface of the truncated cone, and the cylindrical shutter is also at least 2 along the surface on which the infrared sensors are arranged. The infrared detection device according to claim 5, which is a shutter having a surface.

(22) The pyroelectric infrared sensor is (1)
Alternatively, it is the infrared sensor according to claim 1 (21) or the infrared detecting device according to claim 5.

[Brief description of drawings]

FIG. 1 is an explanatory plan view of an embodiment of an infrared sensor of the present invention.

FIG. 2 is a cross-sectional explanatory diagram of FIG.

FIG. 3 is a cross-sectional explanatory view and a plan explanatory view showing a manufacturing method of an embodiment of the infrared sensor of the present invention.

4A and 4B are a cross-sectional explanatory view and a plan explanatory view showing a manufacturing method of an embodiment of the infrared sensor of the present invention.

FIG. 5 is an explanatory diagram of an electrode structure of another embodiment of the infrared sensor of the present invention.

6A and 6B are a cross-sectional explanatory view and a plan explanatory view showing a manufacturing method of still another embodiment of the infrared sensor of the present invention.

7A and 7B are a cross-sectional explanatory view and a plan explanatory view showing a manufacturing method of still another embodiment of the infrared sensor of the present invention.

FIG. 8 is an explanatory diagram showing the relationship between an array of infrared sensors and a cylindrical chopper of an embodiment of the infrared detector of the present invention.

FIG. 9 is an explanatory diagram showing a relationship between an array of infrared sensors and a cylindrical chopper of another embodiment of the infrared detection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infrared detecting element 2 Insulating film 2a Element forming part 2b Bridge part 3 Window part 5 Cavity 6 Substrate 6a Lattice part 7 Thin film 8 Reflective film 18 Sensing element array 19 Drum 20 Hole

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G01J 5/02 Q H01L 21/306 37/02 (72) Inventor Yoshikazu Utsumi 8 chome Tsukaguchi Honcho, Amagasaki 1-1 Mitsubishi Electric Co., Ltd. Material Device Research Center (72) Inventor Masatomi Okumura 8-1-1 Tsukaguchi Honmachi, Amagasaki City Mitsubishi Electric Co., Ltd. Material Device Research Lab (72) Akira Yamada 8-chome, Tsukaguchi Honmachi, Amagasaki City 1-1 Mitsubishi Electric Corporation Material Devices Research Laboratory (72) Inventor Takehiko Sato 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Material Devices Research Laboratory

Claims (5)

[Claims] 1. An insulating coating having an infrared detecting element forming portion is provided on a substrate, an infrared detecting element is provided on the element forming portion of the insulating coating, and the infrared detecting element is provided below the element forming portion of the insulating coating. An infrared sensor having a hollow portion, wherein the thin film made of a material having a high wettability to at least the etching liquid of the substrate is provided on the hollow portion side of the insulating coating of the element forming portion. 2. The infrared sensing element is a pyroelectric sensing element, and a pair of comb-shaped electrodes formed on the insulating film so that the comb teeth are staggered, and at least one surface side of the comb-shaped electrode. 2. A pyroelectric film provided on the
Infrared sensor described. 3. A thin film made of a material having a high wettability with an etching solution of the substrate or a material easily soluble in the etching solution is provided in a region of the substrate where an element forming portion is provided, and (b) the thin film. An insulating coating is provided on the substrate and on the surface of the substrate, (c) an infrared detecting element is formed on the element forming portion of the insulating coating, and (d) an etching window is provided near the element forming portion of the insulating coating. (E) A method of manufacturing an infrared sensor, characterized in that the substrate under the element forming portion is etched from the window for etching to form a cavity. 4. The step of providing the insulating film comprises the steps of previously providing a silicon oxide film or a silicon nitride film by a sputtering method at room temperature and then performing heat treatment at 600 to 1000 ° C., or CVD under heating at 600 to 1000 ° C. The method for producing an infrared sensor according to claim 3, which is a step of providing a silicon oxide film or a silicon nitride film by a sputtering method, a sputtering method, or oxidation. 5. A plurality of pyroelectric infrared sensors are arranged on the surface of a cylinder, and a cylindrical shutter having a plurality of holes which rotate in the arrangement direction of the infrared sensors is provided on the front surface of the infrared sensor. Infrared detector.