JPH06194229A - Infrared ray sensor - Google Patents

Abstract

PURPOSE:To provide an infrared ray sensor that avoids cost-up accompanying attachment of a filter, and is provided with a filter which is not damaged even when a highly reliable package sealing method in which a reduced pressure charging of low heat conduction gas is used. CONSTITUTION:An infrared ray sensor is, on the side of infrared ray incidence, provided with an infrared ray absorption film 16, and a thermal type infrared ray detection film 2, that detects infrared ray by utilizing temperature change caused by the heat occurring at the infrared ray absorption film 16, as infrared ray is absorbed, is housed in a package, and is also provided with a filter 72 mounted on a package member, and through the filter 72, infrared ray is made incident, from the outside of the package, on the infrared ray absorption film 16. The infrared ray sensor features a filter where only a reflection preventive film 72a is provided an at least one side of a silicon package.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor of the type which detects infrared rays by utilizing a temperature change caused by heat generated by infrared absorption.

[0002]

2. Description of the Related Art Infrared sensors are classified into quantum type and thermal type. The quantum infrared sensor is a type that obtains a detection signal by guiding an electron / hole pair generated by absorption of infrared light to an external circuit. The thermal infrared sensor is a type that obtains a detection signal by utilizing a temperature change caused by heat generated by absorption of infrared rays.

The quantum infrared sensor is characterized by high sensitivity and high-speed response, but it is required to be kept at a low temperature by cooling in order to reduce noise and it is expensive, so that it is not versatile. On the other hand, the thermal type infrared sensor is one step inferior to the quantum type in terms of sensitivity and response speed, but it can be used at room temperature, consumes less power, and is relatively inexpensive, so it can be used in ordinary homes and buildings. It is put to practical use in factories etc. for sensing human bodies and objects.

Thermal infrared sensors include a pyroelectric type that detects temperature changes by the pyroelectric effect, a thermocouple / thermopile type that detects temperature changes by the Seebeck effect, and a thermistor type that detects temperature changes by the electrical resistance change of a material. is there. Such a thermal type infrared sensor usually uses a filter to remove light in a wavelength range other than infrared or only a light in a desired wavelength range (infrared of a specific wavelength range) in the infrared range. The infrared rays necessary for the infrared absorption film of the infrared detection section are made incident on the infrared absorption film. The reason for mounting the filter is that the thermal infrared sensor has poor wavelength selectivity and has sensitivity in a wide wavelength range, and it feels even light other than infrared light to be detected, causing a lot of noise and malfunctions. This is because there is an inconvenience.

For example, when infrared rays from a human body or an object are captured to sense the human body or an object, it is better to capture only the infrared rays having a peak at a wavelength corresponding to the surface temperature of the human body or the object, which may cause malfunction or disturbance noise. It is desirable to reduce the effect. The peak wavelength becomes longer as the surface temperature of the human body or object is lower. For example, infrared rays emitted from the human body are about 1
It has a peak near 0 μm. So, by the filter,
Only the infrared rays of a certain wavelength range centered on 10 μm are selectively incident on the infrared absorption film to reduce the influence of malfunction and disturbance noise.

FIG. 12 shows an example of the spectral transmittance of a filter having a transmission band centered at about 10 μm. As such a filter, as shown in FIG.
Filter 5 having wavelength selective transmission films 52 on the front and back surfaces of
0 is used. The wavelength selective transmission film 52 is a film in which a high refractive index layer and a low refractive index layer are alternately laminated several dozen to several hundred times. Materials used here include zinc sulfide and lead oxide. In addition, there is a filter in which an antireflection film made of a high refractive index material is provided on one surface of the silicon substrate instead of the wavelength selective transmission film.

In any case, the filter provided with the wavelength selective transmission film is expensive because the high refractive index layer and the low refractive index layer are stacked and deposited many times, and the cost of the mounted infrared sensor is increased. There is a problem of inviting. On the other hand, in the case of an infrared sensor, ingenuity has been attempted in the structure of the infrared detection unit itself in order to increase the sensitivity. For example, by providing an infrared absorbing film such as gold black, the infrared absorption rate can be increased, or by providing the infrared detecting portion on a thin film (thermal insulating film) having a high thermal resistance which is substantially separated from the substrate, It has been carried out to reduce the outflow of heat energy from the infrared detecting section.

In the infrared detecting section provided on the thin film, not only the infrared absorbing film but also the temperature sensitive resistor (thermistor), the extraction electrode and the like are all formed in a thin film shape. As a result, the heat associated with infrared absorption is effectively used to raise the temperature of the detection section, and the sensitivity and response speed are improved. However, there is a limit to improvement measures by devising the structure of the infrared detection unit. This is because in the case of a thin-film type infrared detection unit, the proportion of the thermal energy that flows out from the detection unit that radiates and flows through air is large, so even if the structural change of the detection unit is changed, the thermal energy will flow out. Because it cannot be effectively stopped.

Therefore, in order to reduce the heat energy that escapes from the infrared detecting section through the air and achieves high sensitivity,
The infrared detector may be housed in the package under reduced pressure. In this way, if you put the infrared detector in a decompressed state,
High sensitivity and high speed response can be achieved, and at the same time noise due to air turbulence can be reduced. However, it is difficult to adopt both the mounting of the filter and the reduced pressure state in the package at the same time. Any method of encapsulating the package for maintaining the reduced pressure state in the package for a long period of time is not essential. For example, a sealing method using an organic adhesive cannot be used because gas is generated from the adhesive. Therefore, it is conceivable to use a sealing method in which the package members are bonded together by welding or brazing, while the package member and the filter are bonded together with a low melting point glass. The problem occurs that the filter is damaged when the low melting glass is sealed.

When the filter is adhered to the package member with the low melting point glass, a temperature of 420 to 450 ° C. is required.
The wavelength selective transmission film is peeled off from the silicon substrate. In addition to depressurization, a mode in which a low thermal conductivity gas is enclosed in the package is also useful, but the same problems as in depressurization tend to occur.

[0011]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a highly reliable package encapsulation method capable of avoiding an increase in cost associated with mounting a filter and capable of decompressing and enclosing a low thermal conductive gas. An object of the present invention is to provide an infrared sensor having a filter that is not damaged even when used.

[0012]

In order to solve the above-mentioned problems, an infrared sensor according to the present invention is provided with an infrared absorption film on the infrared incident side, and a temperature caused by heat generated in the infrared absorption film due to absorption of infrared rays A thermal type infrared detecting section for detecting infrared rays by utilizing the change is housed in the package, and a filter mounted on the package member is provided, through which the infrared ray is absorbed from the outside of the package by the infrared absorbing film. In the configuration adapted to be incident on, a filter having only an antireflection film provided on at least one surface of a silicon substrate is used as the filter.

In the infrared sensor of the present invention, it is preferable that the internal space of the package is in a depressurized state or the filter is attached to the package member by low melting glass. A form in which the infrared absorbing film is a wavelength-selective infrared absorbing film having a high absorptivity for infrared rays in a specific wavelength range, particularly a form in which the wavelength-selective infrared absorbing film is made of silicon oxide, or the infrared incident side of the infrared absorbing film A form in which an infrared reflecting layer is provided on the surface opposite to the face, particularly a form in which the infrared reflecting layer is made of aluminum is also a preferable form.

In the infrared sensor of the present invention, it is also preferable that the infrared detecting section is provided on a thin film (heat insulating film) having a high thermal resistance which is substantially separated from the substrate. The heat insulating film reduces the outflow of heat energy from the infrared detecting section. In addition, if not only the infrared absorption film but also the temperature sensitive resistor (thermistor) and the extraction electrode are formed in a thin film in the infrared detection part provided on the heat insulation film, the heat due to infrared absorption can be detected. This greatly increases the temperature of the part, which is advantageous in terms of sensitivity and response speed.

The filter of the infrared sensor of the present invention usually has a thickness of about 400 to 500 μm. The silicon substrate used in this filter is usually a single crystal silicon substrate, and only the antireflection film is provided on both the front and back surfaces of this silicon substrate, or on either the front surface or the back surface. As this antireflection film,
Examples thereof include films of zinc sulfide (ZnS).

As an infrared sensor package of the present invention, a package including two package members of a stem (stem) and a cap can be mentioned. The filter is usually
Often attached to a cap. The stem and the cap are adhesively sealed by welding or brazing. Also,
A space between the filter and the cap is adhesively sealed with low melting point glass.

In the case of the present invention, a form in which a low thermal conductivity gas is enclosed in the package is also useful. When the low thermal conductivity gas is sealed, the inside of the package is usually at normal pressure, but may be pressurized or depressurized. As a low thermal conductivity gas,
Inert gas is preferred. Further, the larger the molecules of the low thermal conductivity gas, the less likely the leakage from the enclosed portion occurs. Specifically, when xenon gas is used as the low thermal conductivity gas,
Outgassing is less likely to occur, which is preferable.

[0018]

In the infrared sensor of the present invention, since the filter is provided with the antireflection film on the front and back surfaces of the silicon substrate, the film forming process of the filter is simple and short, and the filter is inexpensive. . As the filter mounted on the infrared sensor of the present invention, for example, as shown in FIG. 2, a filter which transmits infrared rays in the vicinity of 10 μm without reflection and has a portion having a high transmittance even in a wavelength range of 5 μm or less is used. Infrared selectivity is weakened by allowing light in a wide wavelength range to pass through. However, the spectral transmittance of the filter is
If there is no problem, there is no problem. If there is a problem, if a wavelength-selective infrared absorbing film such as a silicon oxide film is used as the infrared absorbing film, infrared rays are selectively absorbed as shown in FIG. Since it exhibits wavelength selectivity with a high absorption rate for infrared rays in a specific wavelength range), as a result,
The spectral absorptance of the sensor can be set as shown in FIG. 4, which makes it possible to easily perform selective detection of infrared rays of about 10 μm. That is, by using a specific material (silicon oxide) for the infrared absorbing film, it is possible to make up for the fact that the transmission characteristics of the filter are too wide, and to make the same operation as that of a conventional expensive filter.

When it is inconvenient for the infrared ray transmitted through the infrared absorbing film to be absorbed by the lower side of the infrared absorbing film, an infrared reflecting layer (for example, an aluminum layer) is formed on the surface of the infrared absorbing film opposite to the infrared incident side. There is no problem if you set up and return infrared rays. If the internal space of the package is in a decompressed state or filled with low thermal conductivity gas, the heat generated in the infrared absorption film should be effectively used to raise the temperature of the infrared detection part without flowing out through the air. Therefore, the sensitivity and response speed are improved.

When a silicon oxide film is used as an infrared absorbing film, it is easy to form a thin film and can also serve as a protective function for the infrared detecting portion. Moreover, the thermal conductivity is higher than that when gold black or the like is used. It also has the advantage that it is low in heat flow and can be suppressed. When the internal space of the package is depressurized (or gas-sealed), the processing temperature at the time of sealing (450
However, unlike the thick wavelength selective transmission film with a thickness of several μm to a few tens of μm, thermal stress is small and it is difficult to peel it off. Even if the temperature at the time of sealing is high, the filter is not damaged.

If the filter is attached to the package member by low melting point glass, the reliability of the sealing of the filter portion is high and the depressurized state and the gas sealed state in the package can be reliably maintained for a long period of time. Become.

[0022]

Embodiments of the infrared sensor of the present invention will be described below. This invention is not limited to the following embodiments. —Example 1— FIG. 1 shows the entire structure of an infrared sensor according to Example 1.

In the infrared sensor of the first embodiment, the infrared detecting element 1 having the thermal infrared detecting section 2 is housed in a package composed of a stem (base) 60 and a cap (cover) 70 which are package members. ing. The infrared detection element 1 is of a type that performs infrared detection by utilizing a temperature change caused by heat generated by infrared absorption. In the infrared sensor of the first embodiment, the internal space of the package formed by the stem 60 and the cap 70 is in a reduced pressure state. The stem 60 and the cap 70 are sealed and adhered by laser welding in vacuum.

The degree of reduced pressure is maintained at a degree of vacuum higher than 10 ^-2 Torr, for example, about 10 ^-3 Torr. The back surface of the substrate 10 of the infrared detection element 1 is die-bonded to the stem 60 made of ceramic, metal, or synthetic resin via a bonding agent 62. Rod-shaped terminals 64, 64 are attached to the stem 60 by penetrating the upper and lower surfaces of the stem 60. The upper ends of the terminals 64, 64 and the pads 32, 32 of the infrared detecting element 1 are made of gold bonding wire 6
Wiring connection is made at 6 so that driving power is supplied and infrared detection signals are taken out.

On the other hand, a window is opened in the center of the cap 70, and a filter 72 is sealed so as to close the window. This filter 72 is a filter having a thickness of 400 μm in which only antireflection films 72a, 72a of zinc sulfide are provided on the front and back surfaces of a silicon substrate, and has the spectral transmittance shown in FIG. The cap 70 is attached to the cap 70 by adhesion with a low-melting glass, and is reliably sealed so that the reduced pressure state is maintained. The processing temperature at the time of adhesion is about 450 ° C.

In the infrared detecting element 1, as shown in FIG. 1, a thermal insulating film 11 having a large thermal resistance is formed on a substrate 10 made of silicon or the like, and the infrared detecting portion 2 is formed on the thermal insulating film 11. Is provided. The thermal insulation film 11 is a multi-layered structure film formed by sandwiching a 5000 Å-thick silicon oxide film with a 1000 Å-thick silicon nitride film.
A hollow portion (heat separation space) 12 is formed in the substrate 10 on the back side of the heat insulating film 11 corresponding to the installation location of the infrared detection unit 2.
The heat insulating film 11 is in a hollow state in the hollow portion 12 and forms a so-called diaphragm structure. The presence of the heat insulating film 11 makes it difficult for heat to flow out from the infrared detecting section 2, and the heat generated by infrared absorption quickly raises the infrared detecting section 2 to a high temperature.

In the infrared detecting section 2, a lower electrode 13 made of a chromium film having a thickness of 2000 Å is formed on the heat insulating film 11, and a thickness of 2 is provided.
A temperature-sensitive resistor 14 made of an amorphous silicon carbide (SiC) film having a thickness of 1.0 μm is provided so as to be sandwiched by an upper electrode 15 made of a chrome film of 000 Å.
Then, on the upper electrode 15, an infrared absorption film 16 made of a silicon oxide film having a thickness of 1.5 μm and having a spectral absorption rate shown in FIG. 3 is provided. When it is not necessary to consider that the infrared rays transmitted through the infrared absorption film 16 are absorbed by the upper electrode 15, the spectral absorptance of the entire sensor is as shown in FIG. 4, and infrared rays having a wavelength of about 10 μm are selectively detected. Will be done. When the infrared light transmitted through the infrared absorption film 16 is absorbed by the upper electrode 15, the infrared absorption by the upper electrode 15 is added to the infrared absorption by the infrared absorption film 16.

That is, for example, if an infrared reflecting layer is provided between the upper electrode 15 and the infrared absorbing film 16, it is not necessary to consider the infrared absorption by the upper electrode 15.
When the infrared rays transmitted through the infrared absorption film 16 are incident on and absorbed by the upper electrode 15 of the chromium film, the infrared absorption characteristics of the infrared detection element show the spectral absorption rate shown in FIG.
The spectral absorptance of the sensor as a whole is as shown in Fig. 1.
It also has sensitivity to wavelengths other than about 0 μm, for example, infrared rays of 5 μm or less.

The resistance value of the temperature sensitive resistor 14 changes with temperature. In the infrared detecting element 1, since the temperature of the temperature sensitive resistor 14 changes due to the heat generated in the infrared absorbing film 16 and the resistance value changes, it goes without saying that infrared detection is performed by capturing this. Example 2 FIG. 6 shows the entire structure of the infrared sensor according to Example 2,
FIG. 7 shows the structure of the infrared detecting element of the infrared sensor of the second embodiment, and FIG. 8 shows the structure of the filter of the infrared sensor of the second embodiment.

Also in the infrared sensor of the second embodiment, the infrared detecting element 1 having the thermal infrared detecting section 2 is housed in the package consisting of the stem 60 and the cap 70 which are package members. The infrared detection element 1 is of a type that performs infrared detection by utilizing a temperature change caused by heat generated by infrared absorption. The infrared sensor of Example 2 is
The internal space of the package formed by the stem 60 and the cap 70 is in a reduced pressure state. The stem 60 and the cap 70 are
It is sealed and adhered by laser welding in vacuum.

The degree of reduced pressure is maintained at a degree of vacuum higher than 10 ^-2 Torr, for example, about 10 ^-3 Torr. The back surface of the substrate 10 of the infrared detection element 1 is die-bonded to the stem 60 made of ceramic, metal, or synthetic resin via a bonding agent 62. Rod-shaped terminals 64, 64 are attached to the stem 60 by penetrating the upper and lower surfaces of the stem 60. The upper ends of the terminals 64, 64 and the pads 32, 32 of the infrared detecting element 1 are made of gold bonding wire 6
Wiring connection is made at 6 so that driving power is supplied and infrared detection signals are taken out.

On the other hand, a window is opened in the center of the cap 70, and a filter 72 is sealed so as to close the window. The filter 72 is a filter having a thickness of 400 μm in which only the antireflection films 72a, 72a of zinc sulfide are provided on the front and back surfaces of the silicon substrate 72b, and has the spectral transmittance shown in FIG. The cap 70 is attached to the cap 70 by adhesion with a low-melting glass, and is reliably sealed so that the reduced pressure state is maintained. Processing temperature for bonding is about 450
℃.

In the infrared detecting element 1, as shown in FIG. 7, a thermal insulating film 11 having a large thermal resistance is formed on a substrate 10 made of silicon or the like, and the infrared detecting portion 2 is formed on the thermal insulating film 11. Is provided. The heat insulating film 11 is a multi-layer structure film having a total thickness of 1 μm formed by sandwiching a silicon nitride film having a thickness of 1000 Å with a silicon oxide film having a thickness of 8000 Å. A hollow portion (heat separation space) 12 is formed in the substrate 10 on the back side of the heat insulating film 11 corresponding to the installation location of the infrared detection unit 2. In this hollow portion 12, heat insulation is performed. The membrane 11 is hollow and constitutes a so-called diaphragm structure. When the heat insulating film 11 is provided, it is difficult for heat to flow out from the infrared detecting section 2,
The heat generated by the infrared absorption rapidly raises the infrared detection unit 2 to a high temperature.

In the infrared detecting section 2, a lower electrode 13 made of a chrome film having a thickness of 2000 Å and a thickness of 2 are provided on the heat insulating film 11.
A temperature-sensitive resistor 14 made of an amorphous silicon carbide (SiC) film having a thickness of 1.0 μm is provided so as to be sandwiched by an upper electrode 15 made of a chrome film of 000 Å.
Then, on the upper electrode 15, an infrared reflecting layer 17 made of an aluminum layer having a thickness of 0.3 μm and an infrared absorbing film 16 having a spectral absorption rate shown in FIG. It is configured so that it is not necessary to consider that the infrared rays that have been formed and have passed through the infrared absorption film 16 are absorbed by the upper electrode 15.

The resistance value of the temperature sensitive resistor 14 changes with temperature. In the infrared detecting element 1, since the temperature of the temperature sensitive resistor 14 changes due to the heat generated in the infrared absorbing film 16 and the resistance value changes, it goes without saying that infrared detection is performed by capturing this. Each part of the infrared sensor of Example 2 can be formed as follows.

The thermal insulating film 11 is formed by using the plasma CVD method, using monosilane and ammonia or monosilane and dinitrogen monoxide as an introduction gas, the temperature of the substrate 10 is 400 ° C. and 250 ° C., and the frequency is 13.56 MHz.
It can be formed by stacking silicon nitride and silicon oxide under the above condition. In this way, a substrate 1 made of silicon
A thermal insulation film 11 is formed on the surface of 0 and a thin film of silicon nitride is similarly formed on the back surface of the opposite surface.

Then, a 0.2 μm-thick chromium thin film for the lower electrode 13 was formed on the heat insulating film 11 by the vacuum evaporation method under the condition of the substrate temperature of 150 ° C. Then, a photoresist mask for forming the lower electrode pattern is formed on the chromium thin film by using a normal photography technique, and etching is performed in an etching solution containing cerium ammonium nitrate to form a predetermined pattern shape. The photoresist mask was removed to form the lower electrode 13.

Subsequently, an amorphous silicon carbide (SiC) film for the temperature sensitive resistor 14 is formed by plasma CVD, and a photoresist mask for forming the temperature sensitive resistor pattern is formed on the amorphous silicon carbide (SiC) film by plasma CVD. After forming and etching in an etching solution consisting of nitric acid, acetic acid and hydrofluoric acid to form a predetermined pattern,
The photoresist mask was removed to prepare the temperature sensitive resistor 14.

After forming the temperature sensitive resistor 14, a chromium upper electrode 15 is formed in the same manner as the lower electrode 13 described above, and a 0.3 .mu.m thick aluminum for forming the reflection layer 17 is formed thereon. Thin films are laminated by vacuum evaporation method, a photoresist mask for forming a reflective layer pattern is formed on the thin film by using a normal photography technique, and etching is performed in an etching solution composed of phosphoric acid, acetic acid and nitric acid, and a predetermined pattern is formed. Then, the photoresist mask was removed and the reflective layer 17 was formed. After this, the infrared absorption film 16
A thin film of silicon oxide for formation is formed by the plasma CVD method similarly to the case of the heat insulating film, and a photoresist mask for forming an infrared absorbing film pattern is formed thereon by using a normal photography technique. Etching was performed in an etching solution containing ammonium fluoride to form a predetermined pattern and then the photoresist mask was removed to form the infrared absorption film 16. The reflection layer 17 and the infrared absorption film 16 have substantially the same pattern.

After the infrared absorption film 16 is formed, an aluminum thin film having a thickness of 1.5 μm for forming the pad 32 is laminated by a vacuum vapor deposition method, and a photoresist mask for forming a pad pattern is formed thereon by using an ordinary photography technique. Was formed, and etching was performed in an etching solution containing phosphoric acid, acetic acid, and nitric acid to form a predetermined pattern shape, and then the photoresist mask was removed to form the pad 32.

Subsequently, the hollow portion (heat separation space) 12 is formed. A photoresist mask for forming a digging window is formed on the silicon nitride thin film on the back surface of the substrate 10 by using a normal photography technique, and introduced gas (carbon tetrafluoride) is used.
Patterning is performed by plasma etching under the conditions of a pressure of 400 mTorr and a power of 200 W, a window is provided, then the resist mask is removed, and the silicon nitride thin film with a window is used as a mask. Then, the hollow portion 12 was formed and the infrared detection element 1 was obtained. As conditions for anisotropic etching, potassium hydroxide was used as an etchant, the etchant concentration was 40% by weight, and the liquid temperature was 80 ° C.

After this, as shown in FIG. 6, the back surface of the substrate 10 of the infrared detecting element 1 is placed on the stem 60 made of ceramic, metal or synthetic resin, and a bonding agent (adhesive) 62.
Die-bonding via the terminals 64 and 64, and
The pads 32, 32 of the infrared detection element 1 are connected by a gold bonding wire 66, and the cap 7 with the filter 72 is attached.
0 was welded and sealed.

Since the filter 72 is not provided with a selective transmission film, it transmits infrared rays having a wavelength of 5 μm or less as shown in FIG. 2, but the infrared absorption film 16 has an emission wavelength of 5 μm or less as shown in FIG. Infrared rays having a wavelength are hardly absorbed. Moreover, since it is not necessary to consider the infrared absorption of the upper electrode 15 due to the reflective layer 17, the infrared detection element 1 shown in FIG.
As shown in FIG. 9, the spectral absorption characteristics with respect to the infrared energy radiated from a black body at 36 ° C. are as shown in FIG. 9, and the spectrum when the filter with the selective transmission film and the infrared sensor of Example 2 are combined. FIG. 10 showing absorption characteristics
Is the same as That is, it is not necessary to use a filter with a selective transmission film.

From the comparison of FIGS. 9 and 10, the absorption characteristic of the radiant energy from the black body at 36 ° C. is almost the same as that of the conventional sensor using the filter with the selective transmission film, and the total energy is almost the same. Therefore, the infrared sensor of the present invention has no problem in the application to human body sensing. -Example 3-The infrared sensor of Example 3 has the same configuration as that of Example 2 except that the sensor of Example 2 has a configuration in which xenon is enclosed in the package instead of reducing the pressure inside the package. The performance is almost the same as that of the second embodiment.

Even in the infrared sensor of the second embodiment, the infrared detecting element 1 having the thermal infrared detecting section 2 is not limited to the above embodiment. In FIG. 7, the infrared absorbing film 16 and the infrared reflecting layer 17 are realized by one thin film, that is,
As another example, a configuration in which the infrared absorption film 16 and the reflection layer 17 are replaced by a thin film (for example, an aluminum thin film) having both functions can be given. It is very preferable when the infrared reflective layer is made of aluminum having excellent infrared reflectivity.

[0046]

In the infrared sensor of the present invention, since the filter is inexpensive, the cost of the infrared sensor will not be greatly increased by mounting the filter. At most, peeling of the antireflection film does not easily occur, the filter is not damaged, and it is very practical.

When the infrared absorbing film is a wavelength selective infrared absorbing film, there is an added advantage that the lack of the spectral characteristic of the filter is eliminated. When the infrared reflecting layer provided on the surface of the infrared absorbing film opposite to the infrared incident side is provided, it is said that the inconvenience that infrared rays transmitted through the infrared absorbing film are absorbed on the lower side of the infrared absorbing film is eliminated. Added benefits.

When the internal space of the package is in a depressurized state or in a state of being filled with a low thermal conductive gas, the heat generated in the infrared absorbing film is effectively used for raising the temperature of the infrared detecting section without flowing out through the air. Therefore, there is an advantage that the sensitivity and the response speed are improved. Further, if the filter is attached to the package member by adhesion with a low melting point glass, there is an added advantage that it is possible to reliably maintain the decompressed state of the package and the sealed state of the low thermal conductive gas for a long period of time. Rich in sex.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an infrared sensor of Example 1.

FIG. 2 is a graph showing the spectral transmittance of the filter of the infrared sensor of the example.

FIG. 3 is a graph showing a spectral absorptance of a silicon oxide film for an infrared absorption film.

FIG. 4 is a graph showing an example of the spectral absorptance of the entire infrared sensor of the example.

FIG. 5 is a graph showing an example of the spectral absorptance of the entire infrared sensor of the example.

FIG. 6 is a cross-sectional view showing the overall configuration of an infrared sensor of Example 2.

FIG. 7 is a sectional view showing an infrared detection element of the infrared sensor of the second embodiment.

FIG. 8 is a cross-sectional view showing a filter of the infrared sensor according to the second embodiment.

9 is a graph showing spectral absorption characteristics of the infrared sensor of Example 2. FIG.

FIG. 10 is a graph showing the spectral absorption characteristics of the infrared sensor of the reference example.

FIG. 11 is a graph showing the spectral absorptance of the infrared detection element of the infrared sensor of the example.

FIG. 12 is a graph showing a spectral absorption rate of a filter of a conventional infrared sensor.

FIG. 13 is a cross-sectional view showing a filter of a conventional infrared sensor.

[Explanation of symbols]

 1 Infrared Detector 2 Infrared Detector 16 Infrared Absorption Film 17 Infrared Reflection Layer 60 Stem (Package Member) 70 Cap (Package Member) 72 Filter 72a Antireflection Film

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

Subsequently, an amorphous silicon carbide (SiC) film for the temperature sensitive resistor 14 is formed by plasma CVD, and a photoresist mask for forming the temperature sensitive resistor pattern is formed on the amorphous silicon carbide (SiC) film by plasma CVD. Formed and dry etching method (for example, using SF ₆ as a gas)
Existing RIE method, ion milling method using Ar ions, etc.)
Etched by, after the predetermined pattern, creating the temperature-sensitive resistor 14 by removing the photoresist mask.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Fig. 12

[Correction method] Change

[Correction content]

FIG. 12 is a graph showing the spectral transmittance of a filter of a conventional infrared sensor.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 12

[Correction method] Change

[Correction content]

[Fig. 12]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuro Ishida 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Keiji Kakite, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works Co., Ltd.

Claims (7)

[Claims] 1. A thermal infrared detecting section is provided in a package, wherein an infrared absorbing film is provided on an infrared incident side, and infrared detection is performed by utilizing a temperature change caused by heat generated in the infrared absorbing film due to absorption of infrared rays. In an infrared sensor, which is housed and has a filter attached to a package member, through which the infrared rays enter the infrared absorption film from the outside of the package, an antireflection film is used as the filter. An infrared sensor, characterized in that a filter is used, which is provided only on at least one side of a silicon substrate. 2. The infrared sensor according to claim 1, wherein the infrared absorption film is a wavelength-selective infrared absorption film having a high absorption rate for infrared rays in a specific wavelength range. 3. The infrared sensor according to claim 2, wherein the wavelength selective infrared absorbing film is made of silicon oxide. 4. The infrared sensor according to claim 1, wherein an infrared reflecting layer is provided on the surface of the infrared absorbing film opposite to the infrared incident side. 5. The infrared sensor according to claim 4, wherein the infrared reflective layer is made of aluminum. 6. The infrared sensor according to claim 1, wherein the internal space of the package is in a reduced pressure state. 7. The infrared sensor according to claim 1, wherein the mounting of the filter on the package member is bonding with a low melting point glass.