JPH03210437A - Infrared sensor and its manufacture - Google Patents

Abstract

PURPOSE:To improve measuring accuracy by integrating an infrared sensor element and a window material and compensating an output of the infrared sensor element based on a detection result of a pressure detecting means which detects a pressure inside a cavity. CONSTITUTION:Infrared rays emitted from a sample to be measured are introduced into a cavity 13 via an infrared ray input unit 18 of a window material 14 and made incident to an infrared sensor element 12 where they are converted into an electric signal to be output to have a measured value obtained. A pressure detecting means for detecting a pressure in the cavity 13 is provided while an output of the infrared sensor element 12 is compensated based on a detection result of the pressure detecting means. The pressure detecting means is a diffusion resistor layer 17 formed on the infrared ray input unit 18 to set the cavity 13 at a negative pressure. That is, a value of an output signal of the infrared sensor element 12 is compensated according to a change in an inner pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infrared sensor and a method of manufacturing the same, and particularly relates to an infrared sensor suitable for use in a thermometer that measures temperature such as body temperature without contact and a method of manufacturing the same. .

[Prior Art] Infrared sensors have generally been used as non-contact thermometers to measure the temperature of high-temperature objects, moving objects, and substances that have a small heat capacity and whose temperature changes when they come into contact. To give an example, it is used to measure the temperature of blast furnaces in steel factories, fire alarms as a sensor for disaster prevention and safety equipment, and used for security as a sensor to distinguish between animal body temperature and human body temperature. ing. In addition, infrared sensors have recently been used in large quantities to control the temperature of household microwave ovens and refrigerators.

Since these sensors measure the temperature of a distant location from a fixed location, it is not a major problem even if the measurement accuracy is poor or the measurement time is long.

On the other hand, thermometers, particularly thermometers, used in medical equipment are desirably capable of accurate measurement (l/100° C.), fast measurement (3 seconds or less), and inexpensive.

However, conventional electronic thermometers are so-called predictive thermometers that estimate the temperature in a state of thermal equilibrium from the actual measurement value and the elapsed time. In addition, current body temperature measurements are mostly under the armpits or under the tongue, and seriously ill people who have lost their physical strength or the elderly are unable to hold the thermometer during temperature measurement. There were many problems.

By the way, body temperature has traditionally been measured under the armpits or under the tongue, but from a physiological background, it is not thought that the body temperature in the armpits represents the body temperature as a whole. The most accurate method is to measure the core temperature, such as the temperature of the brain, which maintains a stable temperature during surgery.5 This is the temperature necessary for measuring body temperature during surgery. Considering these points, the temperature of the eardrum inside the ear reflects the temperature of the hypothalamus, and because the auditory canal is narrow, it is less susceptible to the influence of wind and infrared rays from the outside air, so it can be said to be the optimal temperature measurement site. .

In addition, non-contact thermometers need to detect minute amounts of infrared rays emitted from objects that have almost no difference in temperature from the outside air, such as body temperature (15 to 50 degrees Celsius), no matter how sensitive or accurate the thermometer is. If it comes into contact with even a small amount of air, it will be affected by wind and heat convection, making accurate temperature measurement impossible.

In order to reduce the effects of such disturbances, it is necessary to protect the infrared sensor by putting it in a package, and this package can also be used as a window material to guide the infrared rays emitted from the object to the infrared sensor without loss. An important issue is to consider the following.

Conventionally, infrared sensors for such non-contact thermometers have been made by covering a metal stem with an infrared sensor element attached to a metal cap member, and a window made of silicon or other material with a window in a part of the cap member. The structure was made of boards pasted together.

[Problems to be Solved by the Invention] However, since the above-mentioned conventional infrared sensor has a structure in which a metal cap member covers a metal stem,
The sealing part requires a flange, which increases the external size and increases the price, making it unsuitable for the above-mentioned in-the-ear thermometer.

Also, when the temperature is as low as body temperature, the infrared wavelength becomes longer wavelength (
8 to 12 μm) is the peak. Therefore, the window material is required to be a material that allows long wavelengths to pass through, has a low reflectance, emits little infrared radiation from the window material itself, and has excellent workability. Furthermore, in order to prevent noise from occurring due to thermal convection of gas within the window material, it is desirable to create a vacuum inside the window material, and the window material is required to have good airtightness.

However, conventional infrared sensors are insufficient in all of these respects, and vacuum leaks tend to occur from the joint between the cap member and the metal stem, resulting in changes in the internal pressure of the cavity, making it difficult to measure accurately. I couldn't.

The present invention has been made in view of such problems, and includes:
It can be miniaturized and the measurement speed is fast (in addition, it has excellent confidentiality, low noise, and stable characteristics).
Even if a vacuum leak occurs, changes in the internal pressure of the cavity can be monitored and measured values can be corrected, improving measurement accuracy and being able to be manufactured at low cost, making it suitable for use in thermometers, etc. The present invention aims to provide an infrared sensor and a method for manufacturing the same.

[Means for Solving the Problems] In order to solve the above conventional problems, an infrared sensor according to the present invention includes a support member, a semiconductor substrate supported on the support member, and a semiconductor substrate formed on the surface of the semiconductor substrate. an infrared sensor element that detects infrared rays and outputs an electrical signal according to the detected amount of the infrared rays; an infrared sensor element that has an infrared input section and a cavity corresponding to the infrared input section, and inputs via the infrared input section; and a pressure detection means for detecting the pressure inside the cavity, and configured to correct the output of the infrared sensor element based on the detection result of the pressure detection means. It is characterized by the fact that

In the infrared sensor according to the present invention, the window material is preferably a semiconductor material, particularly silicon manufactured by a floating zone method.

Further, in the infrared sensor according to the present invention, the infrared input part of the window material is formed to be deformable according to the pressure of the cavity part, and the pressure detection means is a diffusion resistance layer formed in the infrared input part, Furthermore, it is preferable that the cavity portion is set to a linear pressure state.

Further, in the method for manufacturing an infrared sensor according to the present invention, a window material having an infrared input portion and a cavity portion is formed by etching a first silicon substrate, and impurities are selectively diffused into the infrared input portion. a step of forming an infrared sensor element on the surface of the second silicon substrate and forming a silicon oxide film at least in the region where the window material is to be bonded; The cathode side and the window material are placed on the anode side to face each other, and direct anode bonding is performed in a vacuum.The window material is fixed to the surface of the second silicon substrate to cover the infrared sensor element and the cavity portion is placed under linear pressure. The method is characterized by including the step of:

[Function] In the infrared sensor configured as described above, the infrared rays emitted from the object to be measured are introduced into the cavity part through the infrared ray power part of the window material, and are incident on the infrared sensor element, and the infrared rays are emitted from the object to be measured. After being converted into an electrical signal in the sensor element, it is output and a measured value is obtained. If the inside of the cavity is maintained at a linear pressure state, noise will not be generated (and the electrical characteristics will be stabilized, allowing accurate temperature measurement).

However, if a vacuum leak occurs in the cavity and the internal pressure changes, the infrared input part will bend due to the pressure change.
This causes the resistance value of the diffused resistance layer to change, and by detecting a change in the current value in accordance with this change in resistance value, it is possible to monitor leakage of the degree of vacuum. Therefore, measurement accuracy can be improved by correcting the value of the output signal of the infrared sensor element in accordance with this change in internal pressure.

In addition, this infrared sensor has a structure that integrates an infrared sensor element manufactured by microfabrication in a semiconductor process and a window material, and because it does not include a cap member like conventional infrared sensors, the flange of the stem This eliminates the need for the window, making it possible to achieve a smaller size.Furthermore, if the window material is manufactured using a semiconductor process, the size can be further reduced. Further, in particular, by forming the window material using a silicon substrate manufactured by the floating zone method, the transmission efficiency of infrared rays is improved.

In addition, in this infrared sensor, the temperature of the temperature sensing part increases due to the incident infrared rays, but in order to prevent the temperature from escaping as much as possible, the temperature sensing part is placed on a silicon oxide film, which has a thermal conductivity two orders of magnitude lower than that of a silicon substrate. In addition, in order to reduce heat capacity, semiconductor microfabrication technology is used to make the silicon oxide film bridge thinner, narrower, and longer, and the metal from which the electrical signals are extracted is made thinner and thinner, using a metal with poor thermal conductivity, such as titanium. The measurement speed can be increased by using the

In addition, in the method for manufacturing an infrared sensor according to the present invention, the window material formed of a silicon substrate and the silicon substrate formed with an infrared sensor element are bonded in a vacuum by direct anodic bonding, so that the cavity can be easily removed. The inside of the section can be brought into a linear pressure state.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional structure of an infrared sensor according to an embodiment of the present invention.

In the figure, reference numeral 10 denotes a support member called a metal stem made of a metal such as soft iron plated with chrome or gold, and a semiconductor substrate such as a silicon substrate 1 is mounted on this support member lo.
1 is fixed. Furthermore, an infrared sensor element 12 is formed on the surface of this silicon substrate 11, and a window material 14 having a cavity portion 13 is bonded and fixed so as to cover the element 12.

The infrared sensor element 12 is a so-called bolometer element made of a silicon thin film, which detects incident infrared rays and outputs an electrical signal corresponding to the detected amount via an internal lead 15 and an external lead 16 led out vertically. It is.

This infrared sensor element 12 includes a temperature sensing part 12a whose resistance value changes depending on the amount of heat (infrared rays), and the surrounding area by preventing the heat of this temperature sensing part 12a from escaping to the support member 10 through the silicon substrate 11. and a bridge portion 12b for creating a temperature difference between the two.

Since the temperature sensing portion 12a of the infrared sensor element 12 is made of silicon, it has a negative temperature coefficient such that the electrical resistance decreases as the temperature increases.

Further, the silicon of this temperature sensing portion 12a is a thin film made by a sputtering method, and its crystal structure is an amorphous silicon structure. The principle of a detector with this amorphous silicon structure is explained using band theory.
In the forbidden band between the lower end of the conduction band and the upper end of the charge zone, there is a multilevel (), and electrons are also captured in this level. The number of electrons commensurate with the amount of energy is excited from the level in the forbidden band to the conduction band, and as a result, the number of electron carriers in the conduction band increases.

Further, holes corresponding to the number of electrons are generated at the upper end of the filled band. This increase in electrons and holes lowers the electrical resistance detected from the outside. That is, a change in electrical resistance appears that corresponds to the incident infrared energy.

Next, the window material 14 efficiently guides infrared rays from the outside to the infrared sensor element 12, and
It also serves as a pressure sensor that monitors the degree of vacuum leakage in the cavity portion 13 of No. 2.

This window material 14 is formed of a semiconductor material, such as an N-type silicon film (diaphragm), with a film thickness of several μm to several tens of μm, and has an infrared input section 18 on the surface of which is formed with a diffused resistor made of a P-type diffused layer 17. , this infrared input section 18
It is constituted by a support part 19 that supports the peripheral edge of the.

In addition, the window material 14 excluding the infrared input section 18 and the silicon substrate 1
1 is covered and protected by an insulating layer, such as an epoxy resin layer 20, serving as a protective film. The bottom of the window material 14 is bonded to the silicon substrate 11 by direct anodic bonding in a vacuum, thereby setting the cavity portion 13 in a vacuum state.

In other words, if air or nitrogen gas is filled in the cavity 13 or if the temperature sensing part 12a is exposed to the atmosphere, thermal convection may occur or wind blowing through the temperature sensing part 12a may cause noise. or the electrical characteristics may become unstable.

For this reason, the window material 14 is bonded to the silicon substrate 11 by direct anodic bonding in a vacuum, thereby making it possible to easily bring the cavity portion 13 into a vacuum state and preventing these disadvantages.

Here, "direct anode bonding" means that when bonding the window material 14 to the silicon substrate 11, a silicon oxide film is provided on the silicon substrate 11 side and also placed on the cathode side.
with the anode side facing the anode, and heat it to about 450℃ and 35℃ in a vacuum.
This means applying a voltage of 0V. In addition, cavity part 1
3 does not need to be completely vacuum, it may be in a state where the pressure is lower than atmospheric pressure, that is, in a linear pressure state, but preferably lXl0-"
Torr or less.

If a vacuum leak occurs in the cavity 13 over time and the internal pressure changes, the pressure change causes the infrared input part 18 to bend, which causes the resistance value of the P-type diffusion layer 17 to change. By detecting a change in current value in accordance with this change in resistance value via the electrode 2I formed on the upper surface of the P-type diffusion layer 17, leakage of the degree of vacuum can be monitored. Therefore, measurement accuracy can be improved by correcting the value of the output signal of the infrared sensor element 12 according to the change in the degree of vacuum.

A metal film 22 having a high reflectance of infrared rays, such as a gold (Au) film 22, is formed on the inner wall surface of the window material 14. The infrared rays that entered the cavity part 13 are reflected by the temperature sensing part 12a and the bridge part 12b, and are absorbed by the wall surface of the window material 14 and converted into heat. The infrared rays reflected by the gold film 22 are focused on the temperature sensitive section 12a.

Further, a reinforcing section 23 made of a curved surface having a certain curvature is provided at the corner of the ceiling of the cavity section 13, that is, at the connection section between the infrared input section 18 and the support section 19. The mechanical strength of the material is increased. This reinforcing portion 23 allows the thickness of the sensitive portion 18 to be made thin (approximately 2 μm), thereby improving the transmission efficiency of infrared rays.

In addition, when considering suitability as the window material 14, the three points of reflectance, transmittance, and absorption are most important.Among them, if the absorption rate is high, most of the incoming infrared rays will be absorbed by the window material 14.
In addition, the absorbed infrared rays warm the window material 14, and the window material 14 secondarily emits heat (infrared rays). As a result, the sensor will sense infrared rays from the outside (body temperature) and infrared rays from the window material 14, so it is necessary to separate these, resulting in a very complicated system. Silicon has a low absorption rate and is easy to work with, so it is optimal as the window material 14. Silicon has a high reflectance, so its transmittance is about 50%.

Furthermore, in silicon substrates, absorption waveforms due to stretching and bending such as 15i-0-1-31-C- appear at infrared wavelengths of around 10 μm, resulting in poor infrared transmittance. It is preferable to use a wafer manufactured by a floating zone (FZ) method with few atoms or oxygen atoms.

In this way, in the infrared sensor described above, the window material 14 can improve the incidence efficiency of infrared rays, and also improve the efficiency of condensing light to the temperature sensing part 12a.

Furthermore, compared to an infrared sensor with a conventional structure, the window material 14 and the infrared sensor element 12 can each be finely processed using a semiconductor process, and there is no need for a metal cap as a window material. This eliminates the need for a flange, making it possible to significantly reduce the size of the package.

FIG. 2 shows the structure of an infrared sensor according to another embodiment of the present invention.

That is, in the infrared sensor shown in FIG.
is bonded to the upper surface of the silicon substrate 11 to cover only the infrared sensor element 12. However, in this embodiment, the window material 24 is fixed to the surface of the support member 10 with adhesive, for example, in the same manner as the silicon substrate 11. , the structure is such that the entire silicon substrate 11 is covered, and the size can be reduced in this embodiment as well as in the above embodiment.

Components that are the same as those in FIG. 1 are given the same reference numerals and their explanations will be omitted. Further, the external lead 16 can be taken out downward from the support member 10 as in FIG. 1.

Next, the manufacturing method of the above infrared sensor will be specifically explained with reference to FIGS. 3(a) to 3(p), taking the sensor having the structure shown in FIG. 1 as an example. Note that FIGS. 3(a) to 3(P) show the manufacturing process of a cross-sectional structure along II-II@ in FIG. 1.

First, a silicon substrate 30 as shown in FIG. 3(a) is prepared, and as shown in FIG.
Wet oxidation is performed for several minutes to form a silicon oxide film 31 with a thickness of 5,000 yen on the surface. Subsequently, as shown in FIG. 3C, a film with a thickness of 1.5 to 1.5 mm is deposited on the silicon oxide film 31 by a vapor deposition method to serve as a sacrificial layer for forming the bridge portion 12b described above.
A 2.0 μm metal film, for example, a molybdenum film 32 is formed. In addition to the metal film, a phosphorus silicate glass (PSG) film or the like can also be used as this sacrificial layer.

Subsequently, as shown in FIG. 3D, a photoresist film 33 having a thickness of 1.0 μm is coated on the surface of the molybdenum film 32, and a sacrificial layer pattern is formed by ordinary photolithography. That is, after mask alignment, exposure and development are performed, and further heat treatment (hard baking) is performed at 140±2° C. for 90 seconds in a nitrogen (N2) atmosphere.

Next, as shown in the same figure (e), carbon fluoride (CF4) is applied using the patterned photoresist film 33 as a mask.
Plasma etching is performed to selectively remove the molybdenum film 32. Furthermore, gas pressure 5.0OTorr
, Plasma ashing (ashing) is performed for 4.5 seconds under the condition of high frequency power of 500 W, and the photoresist film 33 is removed.

Next, as shown in the same figure (f), the pressure is 0.9 Torr,
Silane (S) was used as a reaction gas at a temperature of 300±2℃
i H4) = 200SCCM, laughing gas (N, 0) =
40005CCM is poured and a film thickness of 9000±1 without added impurities is formed on the entire surface of the wafer using the CVD method (chemical vapor deposition method).
A silicon oxide film 34 of 500 layers is formed.

Next, as shown in FIG. 3(g), sputtering is performed using a silicon substrate (specific resistance: 300 Ω/CDI) as a target, and a film with a thickness of 1.0-
A silicon film 35 of 1.5 μm is formed, and an acceleration voltage of 120 KeV, a dose of 1, and OX I O'S/
Boron ion implantation was performed under the condition of cm'' to form a silicon film 3.
5 to be closer to a neutral semiconductor. Subsequently, the silicon film 35 is crystallized by heating (annealing) for 30 minutes in a nitrogen atmosphere at a temperature of 1100°C. As a result, the aforementioned temperature sensing section 1
The B constant (temperature coefficient of resistance) of 2a can be set to about 5000, and the sensitivity to temperature changes (changes in resistance value) is good.

Next, as shown in the figure (h), a photoresist film 36 with a film thickness of 1.0 μm is formed by coating on the silicon film 35, mask alignment is performed, and after exposure and development, a photoresist film 36 with a thickness of 140 ± 2 A heat treatment (hard baking) at a temperature of 0.degree. C. is performed for 90 seconds to form a pattern of the temperature sensing portion 12a.

Next, as shown in Figure (i), oxygen (o
s ) = 45 ± ISCCM, sulfur fluoride (SFa)
=135±25CCM flowing, pressure 400mToor,
The photoresist film 36 under the condition of high frequency power of 125W
The silicon film 35 is selectively removed by performing plasma etching using as a mask.

Next, as shown in the same figure (j), the electric power 5. OKW, temperature 23
Titanium (Ti
) Sputtering was performed for 91 seconds to obtain a film thickness of 0.6
A titanium film 37 with a thickness of ±0.1 um is formed. Next, the same figure (
As shown in step (k), an electrode pattern of the photoresist film 38 is formed in the same manner as in step (h) above.

Next, as shown in the same figure (I2), boron trichloride (BCffs) = 47SCCM, chlorine CC1!
, * ) = 393CCM, helium (He) = 1500
A titanium electrode film 39 is formed by dry etching for 130 seconds under conditions of a pressure of 135 Pa and a power of 320 W while flowing secM. Then the pressure is 5.0 Torr.
, plasma ashing (ashing) is performed for 4.5 seconds under the condition of high frequency power of 500 W to remove the photoresist 11138. Next, as shown in FIG. 4(m), a pattern of a photoresist film 40 is formed using photolithography for opening the sacrificial layer in the same manner as in the above-described process. Thereafter, as shown in FIG.
20=l: 45 wet etching by 10)
A molybdenum film 32 is formed on the silicon oxide film 34.
An opening 41 is formed that reaches . Subsequently, the wafer is washed with running ultrapure water five times for 5 minutes each time, and further dried by a spin dry method.

Next, as shown in Figure (0), etching is performed using the photoresist film 40 as a mask in an etching solution of phosphoric acid (H3po, ): nitric acid (HNOs): water (H,0) = 5:1:4. The molybdenum film 32 as the sacrificial layer described above is
remove.

Finally, as shown in the same figure (p), the pressure is 5.0"rorr,
Plasma ashing (ashing) is performed for 4.5 seconds under the condition of high frequency power of 500 W to remove the photoresist film 40.

In this way, the silicon film 35 and the titanium electrode film 39
It is possible to manufacture an infrared sensor element 12 having a temperature sensing portion 12a made of the above-mentioned material and a bridge portion 12b made of the silicon oxide film 34.

Next, the method for manufacturing the window material 14 will be explained in FIGS. 4(a) to 4.
This will be explained in detail with reference to (q).

First, as shown in FIG. 4(a), a semiconductor substrate, for example, a P-type silicon substrate 5o manufactured by the floating zone method and having a (110) plane, is prepared, and after cleaning both sides of this silicon substrate 50, An N-type layer (resistivity: 4 to 8 Ω·cgs) 51 is formed on one side by epitaxial growth. Note that this N-type layer 51 may be formed by diffusing N-type impurities into the surface of the silicon substrate 50 using a diffusion method.

Next, as shown in FIG. 2(b), wet oxidation is performed at a temperature of 1100° C. to form a silicon oxide film 52 with a thickness of 8000 μm on both sides. Next, as shown in the same figure (c), N
A photoresist film 53 having a thickness of 1.0 μm is coated on the surface of the mold layer 51, and a pattern corresponding to the diffused resistor is formed by ordinary photolithography for diffused resistors. That is, after mask alignment, exposure and development are performed, and further heat treatment (hard baking) is performed at 140±2° C. for 90 seconds in a nitrogen (N2) atmosphere. Next, the same figure (d)
A photoresist film 53 patterned as shown in
Wet etching is performed using hydrofluoric acid (HF) using as a mask to selectively remove the silicon oxide film 52. For etching, other etching gas (C) (
Plasma etching using F, +O) may also be used. Then, as shown in the same figure (e), the gas pressure was increased to 5.0OTo.
The photoresist film 53 is removed by plasma ashing (ashing) under the conditions of RR, high frequency power of 500 W, and time of 60 seconds.

Next, as shown in FIG. 5F, thermal oxidation is performed at a temperature of 1100° C. to form a thin silicon oxide film 54 with a thickness of about 800 mm on the front surface of the silicon substrate 50 in the region where the diffused resistor is to be formed and on the back surface. Next, boron fluoride (B
F,) at an energy of 100 KeV and a dose of 2.
Boron ions are implanted through the silicon oxide film 54 under the conditions of 0XIO"/Cl11", and dry nitrogen (
), wet oxygen (02) and dry nitrogen (N*
) in gas for 40 minutes (temperature 1100℃)
By performing drive diffusion, a P-type diffusion layer 55 as a diffusion resistance is formed.

Next, as shown in FIG. 6(g), a photoresist film 56 with a thickness of 1.0 μm is coated on both sides, and
A pattern for the infrared input section is formed in the same manner as in Figure (b)).

Next, as shown in FIG. 5(h), the photoresist film 5 is
Silicon oxide film 54 on the back side using pattern 6 as a mask
selectively etched away.

That is, hydrogen fluoride aqueous solution (HF:H, O=l:1
After performing wet etching using 0) for 75 seconds, the wafer is washed with running ultrapure water (DI) five times for 5 minutes each, and then dried by a spin dry method. Next, as shown in FIG. 5(i), selective etching is performed using the photoresist film 56 as a mask to form the infrared input section 18 together with the cavity section 13. Note that the cavity portion 13 may be formed by a method in which etching is performed after anodization.

Next, as shown in (j) of the same figure, the wafer is soaked in sulfuric acid (H,S).
After removing the photoresist film 56 by immersing it twice in a solution of hydrogen peroxide (H20*) = 2'l for 10 minutes each time, it was washed with running ultrapure water five times for 5 minutes each time, and then Dry by spin dry method. next,
In order to form a contact hole, as shown in the same figure (k),
A photoresist film 57 with a film thickness of 1.0 urn is formed by coating, and after mask alignment, exposure and development are performed, and heat treatment (hard baking) is performed at 140±2° C. for 90 seconds in nitrogen (N) gas. conduct. Then the same figure (1)
As shown in the figure, using the patterned photoresist film 57 as a mask, a hydrogen fluoride aqueous solution (HF:H,O
1810) for 45 seconds,
A contact hole 58 is formed in the silicon oxide film 52. Subsequently, the wafer is washed with running ultrapure water five times for 5 minutes each time, and further dried by a spin dry method. Subsequently, as shown in the same figure (m), the photoresist film 57 was removed by immersing it twice in a solution of sulfuric acid (H*5O4):hydrogen peroxide (HiO2) = 2 = 1 for 10 minutes each, and then the photoresist film 57 was removed. The wafer is washed with running ultrapure water five times for 5 minutes each time, and further dried by a spin dry method.

Next, as shown in the same figure (n), the temperature was 230±30℃, and the
．． Sputtering is performed for 91 seconds under OKW conditions to form an aluminum (8β) film 59 with a thickness of 1.0±O, lum. Subsequently, as shown in FIG. 3(0), a photoresist film 60 having a thickness of 1.0 μm is applied to form an electrode pattern. Subsequently, as shown in the same figure (p), after mask alignment, exposure and development were performed, and heat treatment (hard baking) at 140±2°C in nitrogen gas was performed for 9 days.
This is carried out for 0 seconds to form an electrode pattern.

Next, as shown in the same figure (q), boron trichloride (BCl2) = 47SCCM and chlorine (CA m
) = 393 CCM, helium (He) = 15
The patterned photoresist film 60 was coated under the conditions of 135 Pa of pressure and 320 W of power.
The aluminum electrode 61 is formed by dry etching for 130 seconds using as a mask. Then pressure 5
．． Plasma ashing (ashing) is performed for 4.5 seconds under the conditions of 0 Torr and high frequency power of 500 W to remove the photoresist film 60. Finally, a photoresist film is applied and formed on the back surface of the silicon substrate 50, making sure that the photoresist film does not adhere to the inner surface of the cavity part 13, and a gold (Au) film 62 is formed on top of this by tilted evaporation. Thereafter, the photoresist film is removed by ashing. In this way, the window material 14 having a structure including the infrared input section 18 and the cavity section 13 can be manufactured.

After constructing the sensor, a silicon oxide film is formed on the silicon substrate 11 side by plasma CVD at a temperature of 350°C, and then the wafer is placed on the cathode side, and the window material 14 is placed on the anode side in a vacuum ( By heating the window material 14 at approximately 450°C and applying a voltage of 350V at
is bonded onto a silicon substrate 11.

Next, the sensor assembled in this way is pellet-bonded onto the support member 11 on which the external leads 16 are arranged, followed by wire bonding of the internal leads 15, and then bottling with epoxy resin as a protective film. By drying it, an infrared sensor having the structure shown in FIG. 1 can be manufactured. The method of bonding the window material 14 is not limited to the anodic direct bonding method (it is also possible to bond using an organic adhesive such as epoxy, solder, etc.).

Note that two infrared sensors with different degrees of vacuum inside the cavity 3 were created and compared, but since pressure correction was performed, there was almost no difference in performance results.

Although the present invention has been described above with reference to Examples, the present invention is not limited to the above-mentioned Examples, and can be modified in various ways without changing the gist thereof.

For example, in the above embodiment, silicon was used as the material for the window material 14, but semiconductor materials such as germanium (Ge), zinc selenide (ZnSe), gallium arsenide (GaAs), and even thallium bromine iodide (KRS- 5),
It is also possible to use plastic materials such as thallium bromochloride (KRS-6).

[Effects of the Invention] As explained above, the infrared sensor according to the present invention has a structure in which an infrared sensor element manufactured by microfabrication in a semiconductor process and a window material are integrated, and the stem has a flange portion. Since this is not necessary, a small and inexpensive sensor can be realized.

In addition, if the window material is manufactured using a semiconductor process, it will become more compact.In particular, if it is formed using a silicon substrate manufactured by the floating zone method, the transmission efficiency of infrared rays will be improved, and the inside of the cavity will be kept under linear pressure. If it is maintained at a constant temperature, noise will not be generated (and the electrical characteristics will be stabilized, allowing accurate measurements to be made).

Further, even if a vacuum leak occurs in the cavity and the internal pressure changes, the leak in the degree of vacuum can be monitored by the pressure detection means. Therefore, detection accuracy can be improved by correcting the value of the output signal of the infrared sensor element in accordance with this change in internal pressure.

In addition, in the method for manufacturing an infrared sensor according to the present invention, the window material and the silicon substrate on which the infrared sensor element is formed are bonded by direct anodic bonding in a vacuum, making it easy to wire the inside of the cavity of the window material. It has the effect of being able to be in a pressure state.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the structure of an infrared sensor according to one embodiment of the present invention, FIG. 2 is a cross-sectional view of an infrared sensor according to another embodiment of the present invention, and FIGS. ) are a sectional view showing the manufacturing process of the infrared sensor element in Fig. 1, and Fig. 4, respectively.
Figures (a) to (q) are cross-sectional views showing the manufacturing process of the window material of Figure 1. 10...Supporting member, ll-...Silicon substrate 12...
- Infrared sensor element 12a...temperature sensing part, 12b...bridge part 3...
Cavity part, 14. 24... Window material 15... Internal lead, 16... External lead 17... P-type diffusion layer, 1
8... Infrared input part 9... Support part, 20... Epoxy resin layer

Claims (7)

[Claims] (1) A support member, a semiconductor substrate supported on the support member, and an infrared sensor element formed on the surface of the semiconductor substrate that detects infrared rays and outputs an electrical signal according to the detected amount of the infrared rays. an infrared input section; a window material having a cavity corresponding to the infrared input section and guiding infrared rays input through the infrared input section to the infrared sensor element; and a pressure detector for detecting the pressure inside the cavity section. An infrared sensor comprising means for correcting the output of the infrared sensor element based on the detection result of the pressure detecting means. (2) The infrared sensor according to claim 1, wherein the window material is formed of a semiconductor material. (3) The infrared sensor according to claim 2, wherein the semiconductor material is silicon manufactured by a floating zone method. (4) The infrared sensor according to claim 2 or 3, wherein the infrared input section of the window material is formed to be deformable according to the pressure of the cavity section. (5) The infrared sensor according to claim 4, wherein the pressure detection means is a diffusion resistance layer formed in the infrared input section. (6) The infrared sensor according to claim 5, wherein the cavity section is set to a negative pressure state. (7) The method for manufacturing an infrared sensor according to claim 6, wherein the first silicon substrate is etched to produce a window material having an infrared input portion and a cavity portion, and the window material having an infrared input portion and a cavity portion is selectively provided. a step of diffusing impurities to form a diffused resistance layer; a step of forming an infrared sensor element on the surface of the second silicon substrate and forming a silicon oxide film at least in the region where the window material is to be bonded;
The second silicon substrate is placed on the cathode side and the window material is placed on the anode side to face each other, and direct anode bonding is performed in a vacuum.The window material is fixed to the surface of the second silicon substrate and the cavity is placed under negative pressure. A method for manufacturing an infrared sensor, comprising the step of: