JP2824317B2 - PVDF oriented polarization film and method of manufacturing pyroelectric infrared sensor using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a PVDF oriented polarizing film and a method for manufacturing a pyroelectric infrared sensor using the same.

[Related Art] In recent years, researches for infrared sensors operating at room temperature, particularly for two-dimensional integration and integration thereof, have been actively conducted. Among them, a pyroelectric infrared sensor has been selected for its sensitivity and responsiveness. Therefore, it is attracting attention as having high possibility of practical use.

Pyroelectric infrared sensors, especially infrared image sensors, which have been reported so far, use a bulk pyroelectric material such as ceramics or single crystal, and a silicon substrate on which the signal follow-up circuit is formed, by soldering, indium gimp, or the like. The hybrid type connected by the mainstream was the mainstream (R. Watton et al .: SPIE
510 Infrared Technology X, 139-148, 1984.). However, in this method, when the number of elements is large, connection becomes difficult, and crosstalk between the elements becomes a problem.

For this reason, research on thinning of a pyroelectric material has recently become mainstream. In particular, forming a pyroelectric thin film on a silicon substrate is extremely useful because the sensor and the subsequent circuit can be integrated into one chip.

[Problems to be Solved by the Invention] However, it is difficult to form a pyroelectric thin film having a sufficient thickness and performance on a silicon substrate by the conventional method, and this makes a pyroelectric infrared sensor practical. Was a big problem above.

For example, attempts have been made to form a thin film of PbTiO ₃ by sputtering.However, when a silicon substrate is used as a supporting substrate, a pyroelectric thin film having a sufficient orientation has not been obtained yet (M. Okuyama et al .: Jpn.J.Appl.phy.Suppl.2
1,1,1982.).

In addition, some organic copolymers such as P (VDF-TrFE) can easily form a pyroelectric thin film on an arbitrary substrate by spin coating. In this case, however, a pyroelectric thin film is required to have a sufficient orientation. It was necessary to subject the thin film to polarization treatment with high voltage (A. Lee et al .: Thin Solid Films. 181, 24).
5-250, 1989.). However, the polarization treatment of the pyroelectric thin film has been extremely difficult because local electric field concentration occurs due to non-uniform in-plane film thickness or defects, and dielectric breakdown is likely to occur.

Polyvinylidene fluoride (PVDF) is a material suitable for two-dimensional integration of sensors due to its high performance as a pyroelectric thin film, low thermal diffusion coefficient, and easy patterning. This PVDF is classified into an I-type crystal and a II-type crystal. Ferroelectricity can be used as a pyroelectric thin film.

However, according to the conventional technique, only PVDF having a type II crystal can be obtained at the time of ordinary molding, and IDF is obtained from the type II crystal.
The transformation to the type crystal required the stretching operation of the PVDF film and the polarization treatment. For this reason, only a film-shaped thing can be obtained by the conventional manufacturing technique, and it was impossible to form a PVDF oriented polarization film having an I-type crystal on an arbitrary substrate.

Further, in the pyroelectric infrared sensor, forming the pyroelectric material as thin as possible is weight in terms of enhancing infrared detection sensitivity and responsiveness. However, in the prior art, PVDF
The thickness of the film could be reduced to only about 50 μm at most, and there was a limit to the detection sensitivity and responsiveness of the sensor from this aspect.

[Object of the Invention] The present invention has been made in view of such a conventional problem, and a first object of the present invention is to provide a PVDF orientation having an I-type crystal on a membrane electrode provided on a supporting substrate. It is an object of the present invention to provide a method for manufacturing a PVDF oriented polarization film capable of forming a polarization film.

A second object of the present invention is to provide a method for producing a pyroelectric infrared sensor using the above-mentioned method for producing a PVDF oriented polarization film, and using a PVDF oriented polarization film which is sufficiently thin as a pyroelectric material. .

[Object to solve the problem] In order to achieve the first object, a method for producing a PVDF oriented polarization film according to the present invention comprises: a spray nozzle for spraying a PVDF solution; and a membrane electrode provided on a support substrate. Are opposed to each other, and a predetermined electric field is generated between the two, whereby the spray nozzle or the PVDF solution is sprayed toward the membrane electrode, and the solvent in the spray is volatilized using a drying gas,
The PVDF contained in the spray is deposited on the membrane electrode to form a PVDF oriented polarization film.

In this case, the PVDF solution is preferably formed by dissolving PVDF at a concentration of 0.1 to 0.3 wt% in a solvent composed of dimethylformamide or the like.

This is because if the concentration of the PVDF solution is too low, the deposition rate is low, and if it is too high, the PVDF solution precipitates around the nozzle.

The solvent in the spray is preferably volatilized using an inert gas such as a nitrogen gas heated to a temperature of 40 to 80 ° C. as a drying gas.

That is, if the temperature of the nitrogen gas is too low, the solvent is not dried and removed. On the other hand, if it is too high, PVDF containing no solvent reaches the substrate, so that appropriate migration on the film cannot be obtained, and sufficient orientation and uniformity cannot be obtained. Therefore, the above-mentioned nitrogen gas temperature is appropriate.

Further, it is preferable that the electric field between the injection nozzle and the membrane electrode is ± 3.2 to 10 KV / cm on average.

This is because if the electric field between the injection nozzle and the membrane electrode is too low, the deposition rate decreases and large droplets fly, and if it is too high, spark discharge occurs. Therefore, the electric field is preferably set to a value in the above-described range.

In order to achieve the second object, a method of manufacturing a pyroelectric infrared sensor according to the present invention comprises the steps of: forming a membrane electrode on a supporting substrate at least on a bonding surface side with the substrate as an lower electrode, which is made of an etching-resistant material; A step of forming a heat insulating hole by forming a heat insulating hole by etching away a part of the membrane electrode laminating region of the support substrate; and a method of claim 1 on the membrane electrode. Using
A PVDF alignment polarization film forming step of forming a PVDF alignment polarization film, an upper electrode formation step of forming an upper electrode on the PVDF alignment polarization film, and an absorption film forming step of forming an infrared absorbing film on the upper electrode. It is characterized by including.

Here, in order to improve the in-plane uniformity of the PVDF oriented polarization film, a cylindrical focus electrode having a lower potential than the injection nozzle is provided around the movement path of the PVDF spray,
Thereby, it is preferable to control the direction of the ionized PVDF spray. Furthermore, in order to improve the surface uniformity of the film,
Preferably, the membrane electrode is rotated together with the substrate by a motor or the like.

Since the film formation method of the present invention is performed in the air, there is an advantage that a vacuum system is not required and a heating system such as an evaporation method is not required.

Further, the membrane electrode functions as a lower electrode paired with the upper electrode, and is used for generating an electric field with the injection nozzle when forming the PVDF oriented polarization film.

Further, the reason why the junction region of the membrane electrode with the support substrate is formed of an etching-resistant material is to prevent the membrane electrode from being removed by etching in the heat insulating hole forming step.

Further, the formation of the heat insulating holes is intended to reduce the heat capacity of the infrared light receiving unit, reduce the heat conduction from the infrared light receiving unit to the support substrate, and increase the sensitivity and responsiveness of the infrared sensor. The etching for forming the heat insulating hole may be performed from the upper surface side of the support substrate provided with the infrared ray receiving portion, or may be performed from the lower surface side opposite thereto. In particular, when the accuracy of the etching region is required, for example, by increasing the degree of integration of the number of elements, it is preferable to perform etching from the upper surface. The etching from the lower surface is required in a considerable amount to reach the upper surface on which the membrane electrode is formed. This is because alignment errors on the upper and lower surfaces of the support substrate and side etching are likely to occur.

This heat insulating hole forming step may be performed prior to or after the PVDF oriented polarization film forming step.

Preferably, the support substrate is formed as a silicon single crystal substrate, and the heat insulating hole forming step is preferably performed by silicon anisotropic etching.

The use of a silicon substrate as the support substrate is extremely suitable for providing not only an infrared sensor but also a signal follow-up circuit and the like on the same support substrate to integrate the entire circuit.

In addition, the fact that the heat insulating hole forming process is performed by silicon anisotropic etching with less side etching and high accuracy can reduce the variation in sensitivity of the infrared sensor and increase the degree of integration between elements. It is valid.

Preferably, the membrane electrode is formed to include a silicon nitride film formed by low-pressure CVD and a conductive thin film formed thereon.

Here, the use of a silicon nitride thin film formed by low-pressure CVD is because the internal stress of the film is a strong tension, so that the film can be maintained in a stretched state without wrinkling when formed into a thin film membrane. It is. In addition, since silicon nitride is resistant to acids and alkalis, it becomes a favorable etching-resistant material in a later step of forming a heat insulating hole.

Further, the membrane electrode is formed to include a silicon nitride film formed by low-pressure CVD, a polyimide thin film formed by spin coating the silicon nitride film, and a conductive thin film formed on the polyimide thin film. Here, the polyimide thin film is an effective reinforcing material when forming a relatively large-area membrane electrode. At that time, since the thermal conductivity of the polyimide is small, the sensitivity of the infrared sensor hardly changes. It is also compatible with IC processes.

[Operation] Next, the operation of the present invention will be described by taking a case of manufacturing a pyroelectric infrared sensor as an example.

First, a membrane electrode is formed on a supporting substrate. At this time, the support substrate side of the membrane electrode is formed using an etching resistant material. As a result, the membrane electrode remains without being etched away in the heat insulating hole forming step, and forms a thin film membrane structure.
As a result, it is possible to reduce the heat capacity and the heat conduction of the infrared detecting section sequentially formed on the membrane electrode. Reduction of the heat capacity and heat conduction of the infrared detection unit increases the temperature change speed and the temperature change amount at the time of receiving infrared light, and improves the current sensitivity and the voltage sensitivity of the sensor.

Next, a PVDF oriented polarization film having an I-type crystal structure is formed on the membrane electrode as follows.

First, when an electric field is generated between the injection nozzle and the membrane electrode, the electric field causes ionized ions to collect on the surface of the PVDF solution in the injection nozzle.

When the ions are pulled by the electric field and overcome the surface tension of the PVDF solution, the ionized droplet breaks off from the spray nozzle.

In the process of arriving at the membrane electrode, the PVDF in the detached droplet is dried to remove the solvent and ion-clustered. The drying and removal of the solvent during the spraying is carried out at a temperature.
It is preferable to use nitrogen gas heated to 40 to 80 ° C.

Then, when the ion clusters of the PVDF reach the membrane electrode, an oriented polarization film of the PVDF is formed by the effect of the ions.

As described above, according to the present invention, a PVDF oriented polarization film having an I-type crystal is formed on an arbitrary membrane electrode and a substrate.
The coating can be formed without performing the polarization treatment as in the related art, and the above-described conventional problem can be solved.

Since the ionization of the PVDF solution described above is performed by a mild process through a solvent, a so-called fragmentation reaction, such as extraction, cutting, cleavage, and recrystallization of elements, which tends to occur when ionization by electron impact is used, occurs. It is considered difficult. Further, since a heating system or a vacuum system such as vacuum evaporation is not required, low-cost and high-throughput film formation is possible.

When the PVDF oriented polarization film is formed in this way, an upper electrode paired with the membrane electrode is formed on the PVDF oriented polarization film, and further functions as an infrared light receiving unit on the upper electrode. An infrared absorbing film is coated and formed,
The manufacturing process of the infrared sensor ends.

As described above, by applying the present invention to the manufacture of a pyroelectric infrared sensor, a highly sensitive pyroelectric infrared sensor is manufactured using a PVDF oriented polarization film that is sufficiently thin on an arbitrary supporting substrate. be able to.

Further, in the method of the present invention, by using a silicon substrate as the support substrate, it is possible to form the signal follow-up circuit as one chip on the same substrate as the infrared sensor. At this time, the signal output from the pyroelectric infrared sensor usually has a high input impedance.
Impedance conversion is performed by JFET, FET, etc. However, when the follow-up circuit is formed on a separate substrate from the infrared sensor together with the detection unit as in the related art, wiring such as wire bonding is necessary until impedance conversion is performed.
Susceptible to noise. On the other hand, if an infrared sensor and a follow-up circuit can be formed on the same substrate as in the present invention, not only impedance conversion, but also an amplifier and a counter can be incorporated on the same substrate. Become.

When a silicon substrate is used as the support substrate, the heat insulating hole forming step can be performed by silicon anisotropic etching. Since silicon anisotropic etching utilizes the difference in etching grade depending on the crystal orientation, it is possible to perform processing with less side etching on the etching mask. In particular, it is extremely effective when manufacturing a sensor with a high degree of integration in which elements are closely arranged.

Further, by using a silicon nitride film formed by low-pressure CVD as the membrane electrode, since the internal stress of the film is a strong tensile force, when the thin film membrane is formed, it is stretched without wrinkling. Can be maintained. In addition, since silicon nitride is resistant to acids and alkalis, it can be a good etching-resistant material in the step of forming a heat insulating hole. In particular, it functions as a good etching material for a strong alkali which is an anisotropic etching solution for silicon.

When the membrane front electrode is formed to have a relatively large area, the membrane electrode may be broken due to ion cluster impact or the like when a PVDF thin film is formed on the membrane electrode. Therefore, when forming a large-area membrane electrode, this membrane electrode is
It is preferable to form a silicon nitride film formed by CVD, a polyimide thin film formed on the silicon nitride film, and a conductive thin film formed on the polyimide thin film. At this time, the polyimide thin film can be easily formed by spin coating, and can be an effective reinforcing material. Further, since the thermal conductivity is small and the compatibility with the IC process is good, the production yield can be improved without lowering sensitivity or lowering workability.

Also, as described above, by setting the solution concentration of the PVDF solution, supplying nitrogen gas for volatilizing the solvent during spraying, and determining the electric field between the injection nozzle and the membrane electrode, a high pyroelectricity can be obtained. It is possible to form a PVDF oriented polarization film having good properties and uniformity with good control.

[Effects of the Invention] As described above, according to the present invention, I cannot be formed on a membrane electrode or its supporting substrate.
It is possible to favorably form a PVDF oriented polarization film having a type crystal structure.

In particular, by applying the method of the present invention to a pyroelectric infrared sensor, it is possible to obtain a highly sensitive pyroelectric infrared sensor using a PVDF oriented polarizing film having a sufficiently thin and I-type crystal structure. There is an effect that can be.

Embodiment Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

First Embodiment FIG. 1 shows a preferred example of a PVDF oriented polarization film forming apparatus to which the present invention is applied.

In the film forming apparatus of the embodiment, a table 22 on which the sample 10 is placed is provided inside the casing 20, and the table 22 is driven to rotate at a predetermined speed by a motor 24.

The sample 10 is, as shown in FIG.
It is formed by providing a membrane electrode 14 made of silicon nitride formed by low-pressure CVD and aluminum formed by vacuum deposition on the surface of 12.

The film forming apparatus of the present embodiment forms a PVDF oriented polarizing film having an I-type crystal structure with a predetermined film thickness on the membrane electrode. For this reason, in the thin film formation space 20a of the casing 20, the injection nozzle 30 is arranged so as to face the membrane electrode 14. The injection nozzle 30 is supplied with a PVDF solution 80 from a syringe-type container 34 via a pipe 32.

The PVDF solution 80 is preferably formed by dissolving 0.1 to 0.3 wt% of PVDF in a dimethylformamide (DMF) solution. In the embodiment, a solution formed by dissolving 0.2 wt% is used.

Then, a voltage of 8 to 15 KV is applied between the membrane electrode 14 of the sample 10 and the injection nozzle 30 by using the first power supply 36, and an electric field of ± 3.2 to 10 KV / cm is formed between the two on average. doing. This electric field causes the PVDF solution 80 in the injection nozzle 30 to be ionized and formed into a spray form, drawn out of the nozzle 30 and sucked toward the membrane electrode 14.

Further, a nitrogen gas flow 90 heated to a temperature of 40 to 80 ° C. through a pipe 38 is provided in the thin film formation space 20 a inside the casing 20.
Sprayed PVDF supplied from the injection nozzle 30
The solution is dried and the solvent in the spray is volatilized.

In addition, a cylindrical focus electrode 40 having a lower potential than the injection nozzle 30 is disposed around the movement path of the spray-like PVDF applied from the injection nozzle 30 to the membrane electrode 14,
The direction of ionized PVDF spray is controlled. In the embodiment, the second electrode is provided between the focus electrode 40 and the membrane electrode 14.
Is applied with a potential of 4 to 8 KV.

The film forming apparatus according to the embodiment has the above configuration, and the film forming operation will be described next.

First, when a predetermined electric field is generated between the spray nozzle 30 and the membrane electrode 14 of the sample 10 by the first power supply 36, the electric field causes the PVDF solution 80 in the spray nozzle 30 to be ionized and become a spray. Drawn from the membrane electrode
Move toward 14.

In the process of this PVDF spray reaching the membrane electrode 14, the ionized PVDF solution is dried by the nitrogen gas flow 90 heated to a temperature of 40 to 80 ° C. introduced through the pipe 38, and the solvent is volatilized. .

At the same time, the moving direction of the ionized PVDF spray is controlled by the cylindrical focus electrode 40 so as to have a uniform film thickness. Further, in order to improve the uniformity of the film, the sample 10 is rotationally driven by the motor 24, whereby the PVDF film is uniformly deposited on the membrane 14.

Thus, according to the film forming apparatus of the embodiment, the sample 10
A PVDF oriented polarization film having an I-type crystal structure can be uniformly formed on the membrane electrode 14 formed thereon.

When the film deposition apparatus was actually used and the distance between the injection nozzle 30 and the membrane electrode 14 was set to 1.5 to 2.5 cm to form a PVDF oriented polarization film, the deposition rate of the PVDF orientation polarization film was determined. Was 1 μm / h. On the membrane electrode 14 on the silicon substrate 12, a 1 μm-thick PVDF oriented polarization film is deposited,
When the evaluation test was performed, the following results were obtained.

FIG. 2 shows the absorption spectrum characteristics of the PVDF oriented polarizing film by infrared polarized light.

In this absorption spectrum, a characteristic peak of the type I crystal having ferroelectricity (1280 cm ^-1 is observed,
It can be seen that the DF film contains an I-type crystal.

Comparing the spectra of the parallel polarized light and the vertically polarized light with respect to the incident surface, the absorption peak of type I is significantly larger in the case of the parallel polarized light.
It can be seen that the polarization is oriented in a direction perpendicular to.

When the pyroelectric coefficient of the PVDF film was examined, the value showed a large value of ² to 4 nCcm ^-2 K ^-1 .

When the heat resistance was evaluated, the peak of type I was 16
It was confirmed that it did not decrease even after the heat treatment at 0 ° C. for 30 minutes.

Furthermore, even if a material other than aluminum is used as the membrane electrode 14, for example, silicon, an electrode such as ITO is used,
It was confirmed that a PVDF polarization film having similar performance was formed.

As described above, it was confirmed that by using the film forming apparatus of this example, a PVDF oriented polarization film having high pyroelectricity and a thermally stable I-type crystal could be formed without performing stretching or polarization treatment. Was done.

Second Embodiment Next, a preferred example of a method for manufacturing a pyroelectric infrared sensor according to the present invention will be described.

FIG. 3 shows a pyroelectric infrared sensor formed using the manufacturing method of this embodiment.

In the infrared sensor of the embodiment, first, a silicon substrate 12 having a (100) orientation is prepared, and silicon nitride films 50 and 52 are formed on both surfaces of the silicon substrate 12 by low-pressure CVD to a thickness of 100 nm.

The silicon nitride film 52 on the back side of the silicon substrate 12
Is patterned by photo processing and RIE.
Thereafter, a portion of the silicon substrate 12 serving as an infrared detecting portion is removed by etching from the back surface side with a potassium hydroxide solution as a silicon anisotropic etching solution to form a heat insulating hole 16. Thereby, the silicon nitride film 50 provided on the front surface side of the silicon substrate 12 has a thin film membrane structure.

Next, a silicon nitride film 50 having a thin membrane structure
On the surface of the polyimide film by spin coating,
Aluminum is formed thereon as the lower electrode 54 by vacuum evaporation. Thereby, on the surface of the silicon substrate 12,
The membrane electrode 14 including the silicon nitride film 50, the polyimide film, and the lower electrode 54 is formed. In addition,
Since the silicon nitride film 50 has etching resistance,
This membrane electrode 14 is not removed by the anisotropic etching.

Thereafter, on the surface of the membrane electrode 14, a PVDF oriented polarization film 56 is formed in the same manner as in the first embodiment. Finally, aluminum is formed as an upper electrode 58 on the PVDF alignment polarization film 56, and gold black is formed as an infrared absorbing film 60 on the upper electrode 58.

Through the above manufacturing process, the pyroelectric infrared sensor of this embodiment is formed. When this pyroelectric infrared sensor is irradiated with infrared light, the infrared light absorbed by the infrared absorbing film 60 changes the orientation of the PVDF orientation polarizing film 56, and
It will be detected as a change in the electric signal output from 54, 58.

At this time, the infrared sensor of the present invention is a PVDF oriented polarizing film.
The film thickness of 56 is very thin, several μm (1 μm in the example),
Since the electrical characteristics react more sensitively to the infrared light absorbed by the infrared absorbing film 60, the detection sensitivity of the infrared light is extremely high.

In addition, the silicon substrate 12 located below the PVDF alignment polarization film 56 is removed by etching as the heat insulating hole 16. For this reason, the heat capacity and heat conduction of the infrared detecting section are significantly reduced, and the temperature change speed and the temperature change amount at the time of receiving infrared light are increased. From this aspect, the current sensitivity and the voltage sensitivity of the infrared sensor are extremely high. can do.

Table 1 shows the infrared sensitivity of the pyroelectric infrared sensor (light receiving area: 4 mm ² ) thus formed. As a comparative sample, a LiTaO ₃ single crystal sensor (thickness 50 μm, light receiving area 3.1 mm ² ) was used.

From Table 1, it can be seen that the pyroelectric infrared sensor of this embodiment is:
It can be seen that a specific detection capability equivalent to that of the conventional LiTaO ₃ single crystal sensor and a current output nearly three times as large can be obtained.

Thus, it will be understood that a pyroelectric infrared sensor having high sensitivity and high responsiveness can be manufactured according to the method of the present invention.

Third Embodiment Next, another example of the method of manufacturing the pyroelectric infrared sensor according to the present invention will be described.

FIG. 4 shows a pyroelectric infrared sensor formed using the manufacturing method of this embodiment.

In this embodiment, similarly to the second embodiment, the pyroelectric infrared sensor was manufactured by using the PVDF oriented polarization film forming step shown in the first embodiment.

That is, in the infrared sensor of the embodiment, the silicon substrate 12 having the (100) plane orientation is prepared. Then, a sacrifice layer polysilicon indicated by a broken line in the figure is formed as a sacrifice film 66 on a region of the silicon substrate 12 to be an infrared detection unit.

Next, a silicon nitride film 50 is formed on the surface of the silicon substrate 12 by low pressure CVD so as to cover the sacrificial film 66, and a lower electrode 54 is formed on the surface of the silicon nitride film 50. In the embodiment, the lower electrode 54 and the silicon nitride film 50 form the membrane electrode 14.

Then, in the region of the lower electrode 54 that will serve as the infrared detection unit,
A DF orientation polarization film 56 is formed by coating in the same manner as in the first embodiment,
An etching-resistant protective film 62 is formed on the surface of the PVDF oriented polarization film 56 by coating.

Thereafter, an etching hole 64 that reaches the sacrificial film 66 from the surface of the protective film 62 is formed by using a photo process and RIE. Then, when immersed in the silicon anisotropic etching solution later, the silicon anisotropic etching solution is introduced into the inside from the etching hole 64, and the sacrificial film 66 in the portion to be the detection unit
And the silicon substrate 12 in contact therewith is removed by etching, and a heat insulating hole 16 is formed therein. This allows
On the silicon substrate 12, a membrane structure is formed above the heat insulating hole 16.

Then, aluminum is applied to the upper electrode on the protective film 62.
58, and gold black on top of the infrared absorbing film 60
Form as

As described above, according to the manufacturing method of this embodiment, the second
Since the pyroelectric infrared sensor can be manufactured by single-side processing of the silicon substrate 12 without performing double-sided alignment or long-time anisotropic etching as in the embodiment, accurate processing is possible.

In particular, the manufacturing method of this embodiment is extremely suitable for miniaturization, integration, and arraying of pyroelectric infrared sensors.

Fourth Embodiment Next, a preferred fourth embodiment of the present invention will be described.

The feature of this embodiment is that a pyroelectric infrared sensor and a signal processing circuit are integrated on the same substrate 12 to form a so-called integrated sensor.

FIG. 5 shows an example of the integrated infrared sensor of the embodiment. In the integrated infrared sensor of the embodiment, for example, the pyroelectric infrared sensor 100 described in detail in the second and third embodiments is formed at a predetermined position on the silicon substrate 12. Further, on the same silicon substrate 12, a signal processing circuit 110 provided with an FET or an amplifier for impedance conversion of an output signal of the infrared sensor 100, a lead connecting the sensor 100 and the signal processing circuit 110, and an external And a plurality of electrodes 120 for performing the bonding.

The integrated sensor according to the present embodiment is manufactured by the following procedure.

First, a normal L is placed on a silicon substrate 12 having a (100) orientation.
Each circuit part is formed using the SI process.

Thereafter, a pyroelectric infrared sensor 100 is formed in the same manner as in the second and third embodiments. At this time, the membrane electrode 14 functioning as the lower electrode of the sensor 100 is connected to the input gate of the impedance conversion FET, and the upper electrode 58 is connected to the ground.

By doing so, according to the present embodiment, it is possible to manufacture a high-performance and high-performance integrated infrared sensor that is not easily affected by noise.

It should be noted that the present invention is not limited to the above embodiments, and various modified embodiments are possible within the scope of the present invention.

For example, in the above embodiment, a case where a silicon substrate is used as the support substrate has been described as an example. However, the present invention is not limited to this, and the support substrate may be formed using other materials as necessary.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a preferred example of a film forming apparatus used for producing a PVDF oriented polarizing film of the present invention. FIG. 2 is an explanatory view of an infrared-polarized absorption spectrum characteristic of the PVDF oriented polarizing film. FIG. 3 is an explanatory cross-sectional view showing an example of a pyroelectric infrared sensor formed by using the manufacturing method of the present invention. FIG. 4 is another pyroelectric infrared sensor formed by using the manufacturing method of the present invention. FIG. 5 is an explanatory view showing an example of an integrated sensor formed by providing a pyroelectric infrared sensor and other circuits on the same substrate. 12: Silicon substrate, 14: Membrane electrode, 16: Thermal insulation hole, 56: PVDF oriented polarization film, 58: Upper electrode, 60: Infrared absorbing film.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jiro Sakata 41-41, Chuchu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. No. 41 at Yokomichi Inside Toyota Central Research Laboratory Co., Ltd. (56) References JP-A-63-163821 (JP, A) JP-A-63-28081 (JP, A) JP-A-54-154383 (JP, A) JP-A-63-106727 (JP, A) JP-A-61-126439 (JP, A) JP-A-61-79124 (JP, A) JP-A-58-66376 (JP, A) JP-A-53-111500 (JP, A) JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 37/02 G01J 1/02 G01J 5/02

Claims (2)

(57) [Claims] An injection nozzle for injecting a PVDF solution and a membrane electrode provided on a supporting substrate are opposed to each other, and a predetermined electric field is generated between the two, so that the PVDF solution is injected from the injection nozzle into the membrane. Spraying toward the electrode, the solvent in the spray is volatilized by using a gas for drying, PVDF contained in the spray is deposited on the membrane electrode, and a PVDF oriented polarizing film is formed. PVDF
A method for forming an alignment polarization film. 2. A membrane electrode forming step of forming, as a lower electrode, a membrane electrode made of an etching-resistant material at least on a joint surface side with the substrate on a supporting substrate, and etching a part of the membrane electrode laminated region of the supporting substrate. Removing the heat insulating hole by forming a heat insulating hole; and forming a PV on the membrane electrode by using the method of claim (1).
A PVDF alignment polarization film forming step of forming a DF alignment polarization film, an upper electrode formation step of forming an upper electrode on the PVDF alignment polarization film, and an absorption film forming step of forming an infrared absorption film on the upper electrode. A method for manufacturing a pyroelectric infrared sensor, comprising: