JPH0432274A - Pvdf orientation polarized film and manufacture of pyroelectric infrared sensor using the same - Google Patents

Abstract

PURPOSE:To form a PVDF orientation polarized film having an I type crystalline by providing oppositely an injection nozzle for injecting PVDF solution and a membrane electrode, generating predetermined electric field between these nozzle and membrane, injecting the PVDF solution to the membrane electrode from the injection nozzle and depositing PVDF included in the spray of solution on the membrane electrode using a gas for drying process. CONSTITUTION:In the process that the PVDF spray reaches a membrane electrode 14, the ionized PVDF solution is dried up by a nitrogen gas flow 90 which is introduced through a pipe 38 and heated up to 40 to 80 deg.C. Thereby, the solvent is volatiled. Simultaneously, the ionized PVDF spray is controlled in the moving direction so that uniform thickness can be obtained by a cylindrical focus electrode 40. Moreover in view of improving uniformity of film, a sample 10 is rotatably driven by a motor 24 and thereby PVDF film is uniformly deposited on the membrane 14.

Description

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

[Prior Art] In recent years, much research has been conducted on infrared sensors that operate at room temperature, especially with the aim of making them two-dimensional and integrating them.
Among them, pyroelectric infrared sensors are attracting attention as having high potential for practical application due to their excellent sensitivity and responsiveness.

Pyroelectric infrared sensors, especially infrared image sensors, that have been reported so far are made by connecting a bulk pyroelectric material such as ceramics or single crystal to a silicon substrate on which a signal output circuit is formed using solder or indium bump. The mainstream was a hybrid type that connected with
at,: 5PTE 510 InfraredTe
Chnology x, 139-148.1984.
), However, with this method, when the number of elements increases,
Connection becomes difficult and crosstalk between elements becomes a problem.

For this reason, research into thinning pyroelectric materials has recently become mainstream. In particular, forming a pyroelectric thin film on a silicon substrate is extremely useful because it allows the sensor and subsequent circuits to be integrated into one chip.

[Problems to be solved by the invention] However, with conventional methods, it is difficult to form a pyroelectric thin film with sufficient thickness and performance on a silicon substrate.
This has been a major problem in putting pyroelectric infrared sensors into practical use.

For example, attempts have been made to form a PbT10s thin film by sputtering, but so far no pyroelectric thin film with sufficient orientation has been obtained when a silicon substrate is used as a supporting substrate (M, 0kuyaia etat: J
pn, J, Appl, pby, 5upp1.2
1.1.1982. ).

In addition, there are some organic copolymers such as P (VDF-TrFE) that can be easily formed on any substrate by spin coding, but in this case, in order to provide sufficient orientation, pyroelectric thin films can be easily formed on any substrate. It was necessary to polarize the thin film using high voltage (A, Lee et al.: Th
1n 5o11d Pilss, 181,245-2
50.1989. ).

However, polarization treatment for pyroelectric thin films has been extremely difficult because in-plane film thickness unevenness, defects, etc. cause local electric field concentration, which tends to cause dielectric breakdown.

Furthermore, polyvinylidene fluoride (pVDF) is a material suitable for two-dimensionalization and integration of sensors due to its high performance as a pyroelectric thin film, low thermal diffusion coefficient, and ease of patterning. This PVDF has ■ type crystal,
Type 2 crystals are available, and those that can be used as pyroelectric thin films have ferroelectric properties.

However, with conventional techniques, it is not possible to obtain PVDFL having a ■-type crystal during normal molding, and the transition from this ■-type crystal to an I-type crystal requires a stretching operation and a polarization treatment of the PVDF film. Ta. Therefore, with conventional manufacturing techniques, only a film-like product can be obtained, and it has been impossible to form a PVDF oriented polarized film having type I crystals on an arbitrary substrate.

Furthermore, in a pyroelectric infrared sensor, it is important to make the pyroelectric material as thin as possible in order to improve infrared detection sensitivity and responsiveness. However, with conventional technology, PVD
The F film could only be made as thin as about 50 μm at most, and this placed a limit on the detection sensitivity and responsiveness of the sensor.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and its first purpose is to provide oriented polarization of PVDF having ■-type crystals on a membrane electrode provided on a support substrate. An object of the present invention is to provide a method for manufacturing a PVDF oriented polarized film that can form a film.

A second object of the present invention is to produce a sufficiently thin film of PVDF as a pyroelectric material by using the method for producing an oriented PVDF polarized film.
An object of the present invention is to provide a method for manufacturing a pyroelectric infrared sensor using an oriented polarization film.

[Means for Solving the Problems] In order to achieve the first object, the method for producing a PVDF oriented polarized film of the present invention includes: a spray nozzle for spraying a PVDF solution; and a membrane electrode provided on a support substrate. By facing each other and generating a predetermined electric field between the two, P is emitted from the injection nozzle.
Spraying a VDF solution toward a membrane electrode, volatilizing the solvent in this spray using a drying gas, and depositing PVDF contained in this spray on the membrane electrode to form a PVDF oriented polarized film. It is characterized by

In this case, the PVDF solution contains 0.1 to 0.0% of PVDF in a solvent such as dimethylformamide F. ! lv
Preferably, it is formed by dissolving it at a concentration of t%.

This is because if the concentration of the PVDF solution is too low, the deposition rate will be low, whereas if it is too high, it will deposit around the nozzle.

Further, the solvent being sprayed is preferably evaporated using an inert gas such as 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 will not be removed by drying. On the other hand, if it is too high, PVDF that does not contain a solvent will reach the substrate, making it impossible to obtain an appropriate microphone 1 nosion on the film and insufficient orientation and uniformity. Therefore, the above nitrogen gas temperature is appropriate.

Further, the electric field between the injection nozzle and the membrane electrode is on average ±3.2 to 1. It is preferable to set it as OKV/cm.

This is because if the electric field between the injection nozzle and the membrane electrode is too low, the deposition rate will be reduced and large droplets will fly, whereas if it is too high, spark discharge will occur. Therefore,
The electric field is preferably set to a value within the range described above.

In addition, in order to achieve the second object, the method for manufacturing a pyroelectric infrared sensor of the present invention includes forming a membrane electrode as a lower electrode on a supporting substrate, at least on the side of the bonding surface with the substrate, which is made of an etching-resistant material. a thermal insulation hole forming step of forming a thermal insulation hole by etching and removing a part of the membrane electrode lamination area of the supporting substrate; and a method according to claim (1) on the membrane electrode. using P
a PVDF oriented polarized film forming step for forming a VDF oriented polarized film; an upper electrode forming step for forming an upper electrode on the PVDF oriented polarized film; an absorbing film forming step for 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 polarized film, a cylindrical focus electrode having a lower potential than the injection nozzle is installed around the movement path of the PVDF spray, thereby directing the ionized PVDF spray. It is preferable to control. Furthermore, in order to improve the surface uniformity of the membrane, it is preferable to rotate the membrane electrode together with the substrate using a motor or the like.

The film forming method of the present invention is advantageous in that it does not require a vacuum system and also does not require a heating system such as a vapor deposition method because it is performed in the atmosphere.

Further, the membrane electrode functions as a lower electrode paired with the upper electrode, and is used to generate an electric field between the membrane electrode and the injection nozzle when forming the PVDF alignment polarized film.

Furthermore, the joining region of the membrane electrode with the supporting substrate is formed of an etching-resistant material in order to prevent the membrane electrode from being etched away in the thermal insulation hole forming step.

Further, the formation of the thermal insulation hole is for reducing the heat capacity in the infrared light receiving section and reducing heat conduction from the infrared light receiving section to the support substrate, thereby increasing 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 light receiving section, or from the lower surface side on the opposite side.

In particular, when the degree of integration of the number of elements is not increased and precision of the etching area is required, it is preferable to perform etching from the upper surface. Etching from the bottom surface is
This is because a considerable amount is required to reach the upper surface where the membrane electrode is formed, and this tends to cause alignment errors between the upper and lower surfaces of the support substrate, zide etching, etc.

This thermal insulation hole forming step may be performed before or after the PVDF alignment polarization film forming step.

Further, the supporting substrate is preferably formed as a silicon single crystal substrate, and the step of forming the thermal insulation hole is preferably performed by silicon anisotropic etching.

In this way, using a silicon substrate as a support substrate is extremely suitable for integrating not only an infrared sensor but also a signal output circuit and the like on the same support substrate.

In addition, the fact that the thermal insulation hole formation process is performed by highly accurate silicon anisotropic etching with less side etching can reduce variations in the sensitivity of infrared sensors, and can also be used to increase the degree of integration between elements. It is valid.

Further, the membrane electrode is preferably 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 strong tension, so when it is made into a thin film membrane, it does not wrinkle and can be maintained in a tensile state. It is. Furthermore, since silicon nitride is resistant to acids and alkalis, it becomes a good etching-resistant material during the subsequent step of forming thermal insulation holes.

Further, the membrane electrode is formed to include a silicon nitride film formed by low pressure CVD, a polyimide thin film formed on this silicon nitride film by spin code, and a conductive thin film formed on this polyimide thin film. You may.

Here, the polyimide thin film becomes an effective reinforcing material when forming a membrane electrode with a relatively large area. At this time, since polyimide has a low thermal conductivity, the sensitivity of the infrared sensor hardly changes.

It also has good compatibility with IC processes.

[Function] Next, the function of the present invention will be explained using an example of manufacturing a pyroelectric infrared sensor.

First, a membrane electrode is formed on a support substrate.

At this time, the supporting substrate side of the membrane electrode is formed using an etching-resistant material. As a result, this membrane electrode remains without being etched away in the thermal insulation hole forming step, forming a thin film membrane structure. As a result, it is possible to reduce the heat capacity and heat conduction of the infrared detecting sections that are successively laminated on this membrane electrode.

Reducing the heat capacity and heat conduction of the infrared detection section increases the speed and amount of temperature change when receiving infrared light, and improves the current sensitivity and voltage sensitivity of the sensor.

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

First, when an electric field is generated between the injection nozzle and the membrane electrode, ionized ions gather on the surface of the PVDF solution within the injection nozzle due to this electric field.

The ions are pulled by the electric field, which overcomes the surface tension of the PVDF solution, causing the ionized droplets to leave the injection nozzle.

In the process of reaching the membrane electrode, the solvent is dried and removed from the PVDF in the separated droplets, and the PVDF is formed into ion clusters. The drying and removal of the solvent during the spraying is preferably performed using nitrogen gas heated to a temperature of 40 to 80°C.

When the PVDF ion clusters reach the membrane electrode, a PVDF oriented polarization film is formed by the effect of the ions.

As described above, according to the present invention, it is possible to coat an arbitrary membrane electrode and substrate with a PVDF oriented polarized film having type II crystals without performing polarization treatment as in the conventional method. can solve the following problems.

Furthermore, since the ionization of the PVDF solution mentioned above is carried out through a mild process through the solvent, so-called fragmentation reactions such as element abstraction, cutting, cleavage, and recombination, which tend to occur when ionization by electron impact is used, are less likely to occur. it is conceivable that. Furthermore, since a heating system or a vacuum system such as vacuum evaporation is unnecessary, low cost and high throughput film formation is also possible.

Once the PVDF oriented polarized film is formed in this manner, an upper electrode that is paired with the membrane electrode is formed on the PVDF oriented polarized film, and an infrared light receiving section 12 is further formed on this upper electrode. A functional infrared absorbing film is deposited and the infrared sensor manufacturing process is completed.

As described above, by applying the present invention to the production of a pyroelectric infrared sensor, a highly sensitive pyroelectric infrared sensor can be produced using a sufficiently thin PVDF oriented polarization film on any supporting substrate. be able to.

Furthermore, in the method of the present invention, by using the support substrate (2) and a silicon substrate, it becomes possible to form the signal readout path as a single chip on the same substrate as the infrared sensor. Since the signal output from the pyroelectric infrared sensor usually has a high input impedance, it is impedance-converted using a JFET, FET, etc.However, as in the past, the readout circuit along with the detection part is on a separate board from the infrared sensor. If this is the case, wiring such as wire bonding is required before the impedance is converted, making it susceptible to noise.

On the other hand, if an infrared sensor and a readout circuit can be formed on the same substrate as in the present invention, not only impedance conversion but also amplifiers, counters, etc. can be incorporated on the same substrate. It becomes possible.

Further, when a silicon substrate is used as the support substrate, the step of forming the thermal insulation hole can be performed by silicon anisotropic etching. Silicon anisotropic etching makes use of differences in etching grade depending on crystal orientation (7), so it is possible to perform processing with less side etching on the etching mask.

In particular, it is extremely effective when manufacturing highly integrated sensors in which elements are located in close proximity.

In addition, by using a silicon nitride film formed by low pressure CVD as the membrane electrode, the internal stress of the film is a strong tensile force, so when a thin film membrane is formed, it can be stretched without wrinkles. It can be maintained with Furthermore, since silicon nitride is resistant to acids and alkalis, it can serve as a material with good etching resistance during the step of forming thermal insulation holes. In particular, it functions as a good etching-resistant material against a strong alkali, which is an anisotropic etching solution for silicon.

In addition, when the membrane electrode is formed to have a relatively large area, the membrane electrode may be destroyed due to impact of ion clusters, etc. when forming a PVDF thin film on the membrane electrode. Therefore, when forming a membrane electrode with a large area, this membrane electrode
It is preferable to form a silicon nitride film formed by low pressure CVD, a polyimide thin film formed on this silicon nitride film, and a conductive thin film formed on this polyimide thin film. At this time, the polyimide thin film can be easily formed into a thin film using a spin cord, and can serve as an effective reinforcing material. In addition, its thermal conductivity is small, and I
Since it is highly compatible with the C process, it is also possible to improve the manufacturing yield without causing a decrease in sensitivity or workability.

In addition, as mentioned above, by setting the solution concentration of the PVDF solution, supplying nitrogen gas for solvent volatilization during spraying, and determining the electric field between the spray nozzle and the membrane electrode, a high pyroelectric It becomes possible to form a PVDF oriented polarized film with good properties and uniformity in a well-controlled manner.

[Effects of the Invention] As explained above, according to the present invention, a PVDF oriented polarized film having an I-type crystal structure, which could not be formed conventionally, can be satisfactorily formed on a membrane electrode or its supporting substrate. becomes possible.

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 polarized film that is sufficiently thin and has an I-type crystal structure. There is an effect that it can be done.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings.

First Embodiment FIG. 1 shows a preferred example of a PVDF orientation/distribution polarization device to which the present invention is applied.

The film forming apparatus of the embodiment includes a table 22 on which a sample 10 is placed inside a casing 2o, and this table 22 is driven to rotate at a predetermined speed by a motor 24.

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

The film forming apparatus of this embodiment forms a PVDF having an I-type crystal structure with a predetermined film thickness on the membrane electrode 14 by orientation, orientation, polarization, and so on. For this reason, a spray nozzle 3o is arranged in the thin film forming space 20a of the casing 20 so as to face the membrane electrode 14. This injection nozzle 3o is connected to a syringe-shaped container 34 through a vibrator 32.
A VDF solution 80 is provided.

This PVDF solution 80 is dimethylformamide (DM
F) It is preferably formed by dissolving PVDF in a solution of 0.1 to OJ vt%, and in the example, 0.2 wt%
A material formed by melting is used.

Then, the membrane electrode 14 of the sample 10 and the injection nozzle 3
0, apply a voltage of 8 to 15 KV using the first power supply 36, and apply an average of ±3.2 to 10 KV/a between the two.
An electric field of n is formed. Due to this electric field, the PVDF solution 80 in the injection nozzle 30 is ionized and formed into a spray, which is drawn out from the nozzle 30 and drawn toward the membrane electrode 14 .

Moreover, in the thin film forming space 20a inside the casing 20,
A nitrogen gas stream 90 heated to a temperature of 40 to 80° C. is introduced through the vibrator 38 to dry the atomized PVDF solution supplied from the injection nozzle 30 and volatilize the solvent in the atomization.

Further, a cylindrical focus electrode 40 having a lower potential than the injection nozzle 30 is placed around the movement path of the sprayed PVDF from the injection nozzle 30 to the membrane electrode 14, and controls the direction of the ionized PVDF spray. ing. In the embodiment, a potential of 4 to 8 KV is applied between the focus electrode 40 and the membrane electrode 14 using the second power source 42.

The film forming apparatus of this embodiment has the above configuration, and its film forming operation will be explained next.

First, the first power source 36 connects the injection nozzle 3o and the sample 10.
When a predetermined electric field is generated between the membrane electrode 14 of
It moves toward the membrane electrode 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 vibrator 38, and the solvent is volatilized. .

At the same time, the direction of movement of this ionized PVDF spray is controlled by the cylindrical focus electrode 40 so that it has a uniform film thickness. Further, in order to improve the uniformity of the film, the sample 1o is rotationally driven by a motor 24, so that the PVDF film is deposited uniformly on the membrane 14.

In this way, according to the film forming apparatus of the example, sample 10
On the membrane electrode 14 formed above, a PVDF film having a -type crystal structure can be formed.

When this film forming apparatus was actually used, the distance between the injection nozzle 30 and the membrane electrode 14 was set to 1.5 to 2.5 cm, and PVDF orientation distribution polarization was performed.
The VDF orientation distribution polarization-velocity was 1 μm/h. The membrane electrode 14 on the silicon substrate 12 has a film thickness of 1
When PVDF alignment, orientation, and polarization of μm was performed and an evaluation test was performed, the following results were obtained.

FIG. 2 shows absorption spectrum characteristics due to this PVDF orientation/distribution/polarization-polarized light.

This absorption spectrum shows a characteristic peak (1280an-') of type I crystals having ferroelectric properties, which indicates that this PVDF film contains type I crystals.

Furthermore, when comparing the spectra of parallel polarized light and perpendicularly polarized light with respect to the incident plane, the ■-type absorption peak is significantly larger for parallel polarized light, which indicates that the polarization of the PVDF film is oriented in the direction perpendicular to the silicon substrate 1-2 ( It turns out that there is ~.

Further, when the pyroelectric coefficient of the PVDF film was investigated, it was found to be as large as 2-4nCcrn-2.

Also, when we evaluated the heat resistance, the peak of type ■ was 16
It was confirmed that there was no decrease even after heat treatment at 0° C. for 30 minutes.

Furthermore, it was confirmed that a PVDF polarized film having similar performance could be formed even when a material other than aluminum, such as silicon or ITO, was used as the membrane electrode 14.

As described above, it was confirmed that by using the film forming apparatus of this example, it was possible to form a PVDF oriented polarized film having high pyroelectricity and thermally stable type I crystals without performing any stretching or polarization treatment. It was done.

Second Embodiment Next, a preferred example of the method for manufacturing the pyroelectric infrared sensor of 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 with a (100) plane orientation is prepared, and silicon nitride films 50.
A film is formed for 0 ns.

Then, 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 that will become an infrared detection section is etched away from the back side using a potassium hydroxide solution, which is a silicon anisotropic processing/soching solution, to form a heat insulating hole 16. As a result, the silicon nitride film 50 provided on the surface side of the silicon substrate 12 has a thin membrane structure.

Next, a silicon nitride film 50 having a thin membrane structure is
A polyimide film is formed on the surface using a spin code,
Aluminum is formed thereon as a lower electrode 54 by vacuum evaporation. As a result, a membrane electrode 1 - 4 consisting of a silicon nitride film 50 , a polyimide film, and a lower electrode 54 is formed on the surface of the silicon substrate 12 . Note that since the silicon nitride film 50 has etching resistance, the membrane electrode 14 is not removed by the anisotropic etching.

Thereafter, a PVDF alignment polarization film 6 is formed on the surface of the membrane electrode 14 in the same manner as in the first embodiment. Finally, aluminum is formed on this PVDF orientation distribution polarization 56 as an upper electrode 58, and this upper electrode 58
A goldfish is formed thereon as an infrared absorbing film 60.

Through the above manufacturing process, the pyroelectric infrared sensor of this example is formed. When this pyroelectric infrared sensor is irradiated with infrared rays, the infrared rays absorbed by the infrared absorbing film 60 change the PVDF orientation distribution polarization film 6,
This is detected as a change in the electrical signal output from the picture electrodes 54 and 58.

At this time, in the infrared sensor of the present invention, the PVDF orientation/distribution polarization film type 6 is extremely thin at several μm (1 μm in the example), and its electrical characteristics are sensitive to infrared rays absorbed by the infrared absorbing film 60. Therefore, the detection sensitivity of infrared rays is extremely high.

In addition to this, the silicon substrate 12 located on the PVDF alignment polarization membrane shape 6 is etched away as a thermal insulation hole 16. For this reason, the heat capacity and heat conduction of the infrared detection section are significantly reduced, and the speed and amount of temperature change when receiving infrared light increases.From this point of view, the current sensitivity and 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 of 4 and 2) thus formed. As a comparative sample, LiTa0. Single crystal sensor (thickness 50μ
m, and the light receiving area Ll m+s2) was used.

From Table 1, it can be seen that the pyroelectric infrared sensor of this example has the same specific detection ability as the conventional LiTaO5 single crystal sensor, and 3
It can be seen that a current output nearly twice as large can be obtained.

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

Table 1 Third Example Next, another example of the method for manufacturing the pyroelectric infrared sensor of the present invention will be described.

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

In this example, similarly to the second example, a pyroelectric infrared sensor was manufactured using the PVDF oriented polarization film forming process shown in the first example.

That is, in the infrared sensor of the embodiment, a silicon substrate 12 having a (100) plane orientation is prepared. Then, a sacrificial polysilicon layer shown by a broken line in the figure is formed as a sacrificial film 66 to cover a region of the silicon substrate 12 that will become an infrared detection section.

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

Then, P
A VDF oriented polarized film 56 is coated in the same manner as in the first embodiment, and an etching-resistant protective film 62 is coated on the surface of this PVDF oriented polarized film 56.

Thereafter, an etching hole 64 reaching the sacrificial film 66 from the surface of the protective film 62 is formed using a photo process and RIE. Then, when it is subsequently immersed in a silicon anisotropic etching solution, the silicon anisotropic etching solution is introduced into the etching hole 64, etching away the portion of the sacrificial film 66 that will become the detection part and the silicon substrate 12 that is in contact with it. A heat insulating hole 16 is formed inside it.

As a result, a membrane structure is formed on the silicon substrate 12 above the thermal insulation hole 16.

Thereafter, aluminum is formed as the upper electrode 58 on the protective film 62, and goldfish is further formed thereon as the infrared absorbing film 60.

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

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

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

A 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 an integrated infrared sensor according to the embodiment. The integrated infrared sensor of the embodiment includes, for example, the second . The pyroelectric infrared sensor 100 described in detail in the third embodiment is formed. Furthermore, an infrared sensor 1 is placed on this same silicon substrate 12.
A signal processing circuit 110 equipped with an FET, an amplifier, etc. for impedance conversion of the output signal of 00, a lead connecting the sensor 100 and the signal processing circuit 110, and a plurality of electrodes 120 for connecting with the outside. It is formed.

The integrated sensor of this example is manufactured by the following procedure.

First, each circuit section is formed on a silicon substrate 12 with a (100) plane orientation using a normal LSI process.

After that, the second. Similarly to the third embodiment (step 7), a pyroelectric infrared sensor 100 is formed. At this time, the sensor 100
The membrane electrode 1-4, which functions as a lower electrode, is connected to the input gate of the impedance conversion FET, and the upper electrode 58
are connected to ground respectively.

By doing so, according to this embodiment, it is possible to manufacture a high performance and highly functional integrated infrared sensor that is not affected by noise.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the gist of the present invention.

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

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a preferred example of a film forming apparatus used for manufacturing the PVDF oriented polarized film of the present invention, and FIG.
An explanatory diagram of absorption spectrum characteristics of an F-oriented polarized film for infrared polarized light; FIG. 3 is a cross-sectional diagram showing an example of a pyroelectric infrared sensor formed using the manufacturing method of the present invention; FIG. 5 is an explanatory cross-sectional view of another pyroelectric infrared sensor formed using the manufacturing method of the present invention, which is formed by installing a pyroelectric infrared sensor and other circuits on the same substrate. It is an explanatory view showing an example of an integrated sensor. 1-2... Silicon substrate, 14... Membrane electrode, 16... Heat insulation hole, 56... PVDF alignment polarization film, 58... Upper electrode, 60... Infrared absorption film. Agent Patent attorney Fuse Yukio (1 other person) Figure 5o0 +000 Kuki (cm'') Kaki T Figure

Claims (2)

[Claims] (1) A spray nozzle for spraying a PVDF solution and a membrane electrode provided on a support substrate are made to face each other, and a predetermined electric field is generated between the two, thereby spraying the PVDF solution from the spray nozzle onto the membrane electrode. PVDF alignment, characterized in that the solvent in the spray is evaporated using a drying gas, and the PVDF contained in the spray is deposited on the membrane electrode to form a PVDF alignment polarized film. How to form a polarized membrane. (2) A membrane electrode forming step of forming a membrane electrode as a lower electrode on the support substrate, at least the side of which is bonded to the substrate made of an etching-resistant material, and etching away a part of the membrane electrode lamination area of the support substrate. a heat insulating hole forming step of forming a heat insulating hole by using the method of claim (1) on the membrane electrode;
a PVDF oriented polarized film forming step for forming a VDF oriented polarized film; an upper electrode forming step for forming an upper electrode on the PVDF oriented polarized film; an absorbing film forming step for forming an infrared absorbing film on the upper electrode; A method for manufacturing a pyroelectric infrared sensor, comprising: