JPH11132873A - Piezoelectric detector and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a piezoelectric detector using a piezoelectric thin film that can be compact and highly sensitive with small sensitivity irregularity, by setting on a recess-like part of a detector substrate, a film formation substrate, a lower electrode film, the piezoelectric thin film and an upper electrode film, and providing the film formation substrate with a cantilever beam having an end part fixed to the detector substrate or a beam fixed at both end parts. SOLUTION: A lower electrode film 102, a piezoelectric thin film 103, an upper electrode film 104 and a diaphragm film are set on a recess-like part of a film formation substrate 101. The piezoelectric thin film 103 is constituted in a cantilever having an end part fixed to the film formation substrate 101 or a beam having both ends fixed to the film formation substrate. Since a piezoelectric body is formed of a thin film material, the piezoelectric body can be processed minutely to form a minute detector in a diversified shape easily, and the whole detector can be made compact, thus enabling integration of the detectors. The diaphragm film is formed of a film material directly formed on the film formation substrate 101 or piezoelectric thin film 103. A bond process of a diaphragm and the piezoelectric thin film 103 is eliminated, so that sensitivity irregularities due to the bond process are reduced and reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric detector,
In particular, by using a piezoelectric thin film of the piezoelectric lateral effect type,
The present invention relates to a piezoelectric detector capable of detecting minute acceleration and impact with high sensitivity, and to its manufacture.

[0002]

2. Description of the Related Art At present, dielectrics, especially ferroelectrics, include pyroelectric infrared detectors using pyroelectricity, piezoelectric elements such as acceleration sensors and actuators using piezoelectricity, and polarization inversion. Research and development are being carried out as key materials for nonvolatile memories used and capacitive elements using high dielectric constant characteristics.

[0003] A piezoelectric detector utilizes a "piezoelectric effect" in which a piezoelectric body generates electric charges when a force is applied to the piezoelectric body.
It detects a physical quantity (acceleration, pressure, etc.) and has a feature that the voltage sensitivity is extremely large.

[0004] The amount of charge generated by the piezoelectric effect is affected by the polarization direction of the piezoelectric body. Therefore, the element structure and the polarization axis orientation of the piezoelectric body are important for increasing the sensitivity of the detector. In current piezoelectric detectors, especially acceleration sensors, a sintered material is used as a detection material. The sintered body is composed of grains, but the polarization directions of the grains vary. Therefore, it is necessary to perform a polarization process and align the polarization directions in the same direction.

The structure of the piezoelectric detector is classified according to the direction of the force applied to the piezoelectric body. (1) Parallel to the electric axis (vertical effect type), (2) Right angle to the electric axis (lateral effect type), (3) In-plane displacement parallel to the electric axis. Among them, the lateral effect type structure is a structure in which a piezoelectric body is bonded to an elastic plate having a cantilever beam or a beam structure fixed at both ends, and is characterized by being small in size, high in sensitivity, and capable of detecting minute acceleration and vibration. Further, it can be applied as a high-performance actuator by the inverse piezoelectric effect.

[0006]

However, when a high electric field is applied to the sintered body to perform the polarization treatment as described above,
In particular, when a minute piezoelectric element or a plurality of piezoelectric elements are polarized, there has been a problem that it is not easy to uniformly polarize.

Also, in a manufacturing method of bonding a piezoelectric body to an elastic plate or the like in a detector having a lateral effect structure, if the bonding method is incomplete, there is a problem of causing a variation in sensitivity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piezoelectric detector and a method of manufacturing the same, and in particular, to provide a technique for forming a piezoelectric detector using a piezoelectric thin film, which can be reduced in size and sensitivity and has small sensitivity variations. It is.

[0009]

In order to solve the above-mentioned problems, a piezoelectric detector according to the present invention is provided on a detector substrate provided with a concave-shaped portion, which is formed on the concave-shaped portion provided on the detector substrate. A film substrate, a lower electrode film, a piezoelectric thin film, and an upper electrode film are provided, and the film formation substrate is a cantilever having an end fixed to the detector substrate, or a fixed both ends beam having both ends fixed. Is formed.

[0010] In the piezoelectric detector of the present invention, a lower electrode film, a piezoelectric thin film, an upper electrode film, a lower electrode film, and a lower electrode portion are provided on a concave portion provided on the film deposition substrate. And a diaphragm film, and the piezoelectric thin film forms a cantilever beam whose ends are fixed to a film-forming substrate, or a fixed-end beam whose both ends are fixed.

Further, in the piezoelectric detector of the present invention, the lower electrode film, the piezoelectric thin film, the upper electrode film, and the diaphragm film are provided on the concave portion provided on the film forming substrate. The thin film forms a cantilever beam whose end is fixed to the film-forming substrate, or a beam having both ends fixed at both ends.

In order to solve the above problems, a method of manufacturing a piezoelectric detector according to the present invention comprises the steps of: forming a lower electrode film on a film forming substrate; forming a piezoelectric thin film on the lower electrode film; Forming an upper electrode film on a piezoelectric thin film, cutting the film-forming substrate, fixing the cut film-forming substrate on a detector substrate, and cantilevering the concave shape portion provided on the detector substrate. Alternatively, the method includes a step of forming fixed beams at both ends, and a step of cutting the detector substrate to produce a detection unit structure.

Further, the method of manufacturing the piezoelectric detector according to the present invention comprises:
Forming a lower electrode film on the deposition substrate, forming a piezoelectric thin film on the lower electrode film, forming an upper electrode film on the piezoelectric thin film, placing the deposition substrate on a detector substrate And a step of disposing a piezoelectric thin film on the concave-shaped portion provided on the detector substrate, and a step of cutting the film-forming substrate and the detector substrate to produce a detector structure.

Further, in the method of manufacturing a piezoelectric detector according to the present invention, a step of bonding a film-forming substrate on a detector substrate, a step of forming a lower electrode film on the film-forming substrate bonded to the detector substrate, Forming a piezoelectric thin film on the lower electrode film, forming an upper electrode film on the piezoelectric thin film,
Forming a diaphragm film on the upper electrode film, and removing a film-forming substrate portion located below the piezoelectric thin film from the front side on which the piezoelectric thin film is formed through an etching hole provided in the lower electrode film by etching. Forming a concave portion, and cutting the film-forming substrate and the detector substrate to produce a detecting portion structure.

Further, in the method of manufacturing a piezoelectric detector according to the present invention, a step of forming a lower electrode film on a film forming substrate, a step of forming a piezoelectric thin film on the lower electrode film, A step of forming an upper electrode film, a step of forming a diaphragm film on the upper electrode film, and a step of positioning the piezoelectric thin film from the front side under the piezoelectric thin film via an etching hole provided in the lower electrode film. The method includes a step of forming a concave-shaped portion by removing a film-forming substrate by etching, and a step of cutting the film-forming substrate to produce a detection unit structure.

According to the present invention, since the piezoelectric body is a thin film material, fine processing is possible because of the above-mentioned configuration, and a detector having minute and various shapes can be easily formed, and the size of the entire detector can be reduced. This is effective in that integration of detectors and detectors becomes possible.

Further, in the above configuration, the diaphragm film is a film forming substrate,
Alternatively, it is a film material directly formed on a piezoelectric thin film.
Therefore, in the manufacturing process, a bonding step between the diaphragm and the piezoelectric thin film is not required, and the variation in sensitivity due to the bonding step can be reduced, which is effective in improving reliability.

Further, even in the case of a single crystal substrate material from which a large substrate cannot be obtained, the area of the film formation substrate can be increased by a manufacturing method in which the film formation substrate is bonded to the detector substrate and then formed. Therefore, it is effective in increasing the throughput of the element manufacturing process, and is also effective in reducing the cost of the detector.

Furthermore, a beam detector having only a piezoelectric thin film, an electrode film, and a diaphragm thin film is effective in that the beam structure has a small spring constant and can detect minute vibration with high sensitivity. .

Further, the orientation of the crystal structure of the piezoelectric thin film can be controlled, and the polarization axis can be oriented perpendicular to the surface of the film formation substrate. Therefore, it is possible to detect the generated charges effectively. further,
By a film formation method such as a sputtering method, a piezoelectric thin film in which spontaneous polarization is aligned in one direction can be formed without performing polarization processing, and it is not necessary to perform polarization processing. Therefore, it is effective in that a thin film material having uniform piezoelectric characteristics can be prepared.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for manufacturing a piezoelectric detector according to the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a cross-sectional view showing a manufacturing process of a piezoelectric detector according to an embodiment of the present invention, and FIG. A (100) MgO single crystal substrate (thickness: 300 μm) was used as the deposition substrate 101. Then, the deposition substrate 101
A lower electrode film 102, a piezoelectric thin film 103, and an upper electrode film 104 were formed thereon. Pt thin films were formed as the lower electrode film 102 and the upper electrode film 104 by a high-frequency magnetron sputtering method. The sputtering film forming conditions are as follows: the substrate temperature is 600 ° C., and the sputtering gas is Ar (95%) and oxygen (5
%), The gas pressure was 0.5 Pa, the high frequency power density was 2.5 W / cm ² (13.56 MHz), and the film formation time was 1 hour. The thickness of the film was 0.15 μm. The materials shown in Table 1 were produced as the piezoelectric thin film 103 under the specified film forming conditions. By forming the films under the conditions shown in Table 1, all the dielectrics are c-axis oriented single crystal films whose polarization axes are preferentially oriented perpendicular to the substrate surface (100).
Obtained on a MgO single crystal substrate. Next, the upper electrode 104 is
Patterned by sputter etching (Fig. 2
(A)). The etching conditions for the Pt thin film are as follows:
6 Torr, Ar gas flow rate 10 sccm, plasma power 170
It took 15 minutes under the condition of W. Next, 103 is shown in Table 2
The patterning was performed under the process conditions shown in FIG.

[0023]

[Table 1]

[0024]

[Table 2]

Subsequently, the film forming substrate 101 is set to a thickness of 10 to 20.
After polishing to about μm, it was cut into a rectangular shape having a width of about 0.1 mm and a length of about 2 mm (FIG. 2B).

The cut film-forming substrate 101 is adhered and fixed so that the piezoelectric thin film 103 is disposed on the concave-shaped portion 106 of the detector substrate 105, and then cut along a dotted line to collectively detect the film. A structure was produced. (Figure 2
(C)). In this embodiment, 105 made of glass is used,
An epoxy adhesive was used for adhesion. However, the glass substrate and the MgO single crystal substrate can be fixed by direct bonding. There is no problem even if a single crystal Si substrate is used as 105. FIG. 2C shows a case where a cantilever beam is formed, but it is also possible to manufacture a both-end fixed beam structure in this step and use it as a piezoelectric detector. After connection, 1
After the external electrode connection holes are formed by the sandblasting method at 05, the detector electrodes 108 and 1 formed on the 105 are formed.
02 and 104 were respectively connected by bonding wires 109 (FIG. 2D). 110 and 111 are 105
A field effect transistor and a resistor for impedance conversion, which are mounted on the device. Finally, the sealing cap 112 made of glass was joined to the 105 by a direct joining technique to seal the entire detector (FIG. 2E).

In the present invention, the film-formed substrate that has been thinned by polishing functions as a diaphragm. Therefore, since there is no need to bond the piezoelectric thin film and the diaphragm, variation in sensitivity can be reduced, which is effective in improving reliability.

In the present invention, since the polarization axis of the piezoelectric thin film is oriented perpendicular to the surface of the film-forming substrate, high piezoelectric characteristics can be expected without performing the polarization treatment. Therefore,
This is effective in increasing the sensitivity of the detector.

(Embodiment 2) FIG. 3 shows a piezoelectric detector according to an embodiment of the present invention, and FIG.

As the film forming substrate 201, a (100) Si single crystal substrate (400 μm thick) was used. Then, a lower electrode film 202, a piezoelectric thin film 203, and an upper electrode film 204 were formed on the deposition substrate 201. Pt thin films were formed as the lower electrode film 202 and the upper electrode film 204 by a high-frequency magnetron sputtering method. The sputtering film forming conditions were as follows: the substrate temperature was 600 ° C., the sputtering gas was a mixed gas of Ar (95%) and oxygen (5%), the gas pressure was 0.5 Pa, and the high frequency power density was 2.5 W / cm ² ( 13.56 MHz)
Thus, the film formation time was 1 hour. The film thickness is 0.15μ
m. As the piezoelectric thin film 203, lead zirconate titanate (PZT) having a composition having a rhombohedral crystal structure was produced. The difference in the production conditions from the tetragonal PZT shown in Table 1 is as follows.
If the target composition is (Pb _0.56 Zr _0.44 TiO ₃ +0.
2PbO). As a result, a (111) plane oriented PZT film in which the polarization axis was preferentially oriented perpendicular to the substrate surface was obtained on the (100) Si single crystal substrate. Regardless of the orientation of the crystal plane of the Si single crystal substrate, (11
1) A plane-oriented PZT film was obtained. Next, Pt was patterned by sputter etching to produce 204 (FIG. 4A). The etching conditions for the Pt thin film required 15 minutes under the conditions of a vacuum degree of 0.06 Torr, an Ar gas flow rate of 10 sccm, and a plasma power of 170 W. Then, 203
Was patterned under the same conditions as in the process of tetragonal PZT shown in Table 2.

Subsequently, the film forming substrate 201 is set to a thickness of 10 to 20.
After polishing to about μm, the film-forming substrate 201 was bonded and fixed so that the piezoelectric thin film 203 was disposed on the concave portion 206 provided on the detector substrate 205 (FIG. 4B).
In the present embodiment, glass 205 was used, and 201 and 205 were fixed by a direct bonding technique. Si as 205
There is no problem even if a single crystal substrate is used. Further, bonding with an adhesive is also possible. After joining, the line segment α− in FIG.
By cutting at α ′, β−β ′, and γ−γ ′, a cantilever-shaped detection unit structure was manufactured in a lump (FIG. 4D). In the present embodiment, it was cut into a size of 0.075 mm in width and 2 mm in length. In this cutting step, if only the line segment γ-γ ′ is cut, it is possible to collectively manufacture the detection unit structure having the fixed beam structure at both ends.

Finally, the detector board 205 is connected to the circuit board 20.
7 are bonded and fixed to the bonding wires 2
10 and the metal stem 212 and the cap 213
Was sealed by welding. Reference numerals 208 and 209 denote field effect transistors and resistors for impedance conversion mounted on 207.

In the present invention, the film-formed substrate thinned by polishing functions as a diaphragm. Therefore, since there is no need to bond the piezoelectric thin film and the diaphragm, variation in sensitivity can be reduced, which is effective in improving reliability.

Further, in the present invention, since the polarization axis of the piezoelectric thin film is oriented perpendicular to the surface of the film-forming substrate, high piezoelectric characteristics can be expected without performing polarization processing. This is effective in increasing the sensitivity.

Further, according to the present invention, a small-sized piezoelectric detecting structure can be efficiently and collectively manufactured by cutting the film-forming substrate after bonding it to the detector substrate. This is effective in reducing the cost of the vessel.

(Embodiment 3) FIG. 5 shows a piezoelectric detector according to an embodiment of the present invention, and FIG.

A (100) MgO single crystal substrate (thickness: 300 μm, 15 mm square) as a film forming substrate 301 was bonded directly to a 6-inch (100) Si single crystal wafer as a detector substrate 302 by direct bonding. Note that even if a glass substrate is used as 302, direct bonding is possible. Then, the film was polished to a thickness of about 10 to 20 μm (FIG. 6A). In order to reduce the thickness of the deposition substrate 301, a process by etching can be used in addition to polishing.

Next, the lower electrode film 30 is formed on the film formation substrate 301.
As No. 3, a Pt thin film was prepared. The manufacturing conditions are as follows: a high-frequency magnetron sputtering method, a substrate temperature of 600 ° C., a sputtering gas of a mixed gas of Ar (95%) and oxygen (5%), a gas pressure of 0.5 Pa, and a high-frequency input power density of 2.5.
W / cm ² (13.56 MHz), and the film formation time was 1 hour. The thickness of the film was 0.15 μm. next,
The lower electrode film 303 was patterned by sputter etching to form an etching hole 304 (FIG. 6).
(B)). The etching conditions for the Pt thin film are as follows:
6 Torr, Ar gas flow rate 10 sccm, plasma power 170
It took 15 minutes under the condition of W. Then, the piezoelectric thin film 30
5 and an upper electrode film 306 were produced. Piezoelectric thin film 30
The materials shown in Table 1 as No. 5 were produced under the specified film forming conditions. By forming the films under the conditions shown in Table 1, all the dielectrics were obtained on a (100) MgO single crystal substrate as c-axis oriented single crystal films in which the polarization axes were preferentially oriented perpendicular to the substrate surface. Next, the upper electrode 306 was patterned by sputter etching under the same conditions as the lower electrode film 303.
Subsequently, the piezoelectric thin film 305 was patterned under the process conditions shown in Table 2 (FIG. 6B). Further, a diaphragm film 307 was formed on the upper electrode film 306 (FIG. 6).
(C)). As 307, a NiCr thin film was produced by a high-frequency magnetron sputtering method. The thickness was the same as that of the piezoelectric thin film 305. The film formation condition is that the substrate temperature is 2
00 ° C, sputtering gas is Ar gas, gas pressure is 0.8P
a, High frequency input power density is 2.5 W / cm ² (13.5
6 MHz). The diaphragm film 307 is made of Pt, C
A metal material having a high Young's modulus such as r or Al is suitable, but there is no problem with an insulator such as SiO2, a resin film, or a photoresist. There is no problem even if the diaphragm film and the electrode film are made of the same material.

Subsequently, the film-forming substrate portion located below the piezoelectric thin film 305 was removed by chemical etching via the etching hole 304 provided in the lower electrode film (FIG. 6D). The etching removal of the MgO single crystal substrate was performed using a hot phosphoric acid aqueous solution (20 wt%) at 80 ° C. Next, the line segments α-α ′, β-β ′, γ-
By cutting at γ ′, δ−δ ′, and ε−ε ′, a cantilever-shaped detection unit structure was manufactured in a lump (FIG. 6).
(F)). Finally, the detector board 302 is connected to the circuit board 309.
After bonding and fixing to the bonding wire 31
2 and the metal stem 314 and the cap 315 were sealed by welding (FIG. 6 (g)). 310, 311
Denotes a field effect transistor and a resistor for impedance conversion mounted on 309.

Although the MgO substrate has been exemplified as the film forming substrate 301, it is clear that other substrates that can be etched, such as a stainless metal substrate and a Si single crystal substrate, are also effective in the present invention. .

In the present invention, the beam structure of the detecting section is composed of only the piezoelectric thin film, the upper and lower electrode films, and the diaphragm film. Therefore, since the thickness of the entire beam structure is small, the spring constant of the beam structure can be reduced. Therefore, it is effective in that even small vibration and acceleration can be detected with high sensitivity.

In the present invention, the diaphragm film is formed directly on the piezoelectric thin film. Therefore, since it is not necessary to bond the piezoelectric thin film and the diaphragm, variation in sensitivity can be reduced, which is effective in improving reliability.

Further, in the present invention, since the polarization axis of the piezoelectric thin film is oriented perpendicular to the surface of the film-forming substrate, high piezoelectric characteristics can be expected without performing the polarization treatment.
This is effective in increasing the sensitivity of the detector.

Further, it is difficult to increase the area of the MgO single crystal substrate or the like exemplified in this embodiment, and the limit is about 30 mm square. In the present invention, the piezoelectric thin film is formed after the deposition substrate is attached to the detector substrate. Accordingly, by increasing the area of the detection substrate, the efficiency of forming the piezoelectric thin film can be increased, and the throughput of the manufacturing process of the detector can be improved, which is effective in reducing the cost of the detector. .

In the present invention, the detector structure is formed by etching. Therefore, compact integration is possible, and it is also possible to create a detector in which a plurality of beam structures are arranged in parallel or two-dimensionally.

In Examples 1 to 3, the piezoelectric materials specified in Table 1 were used. However, it is apparent that the present invention is effective for other piezoelectric thin film materials. Example 1
In (3) and (3), a (100) MgO single crystal substrate was used as a film formation substrate, and in Example 2, a (100) Si single crystal substrate was used. However, it is clear that the material of the film formation substrate is not limited to these.

(Embodiment 4) FIG. 7 shows a piezoelectric detector according to an embodiment of the present invention, and FIG.

A (100) Si single crystal substrate (thickness: 400 μm) was used as the film formation substrate 401. Then, a Pt thin film was formed on the film formation substrate 401 as the lower electrode film 402 under the same conditions as in Example 2. The thickness of the film was 0.15 μm. Next, 402 was patterned by sputter etching to form an etching hole 403 (FIG. 8).
(A)). The etching conditions are the same as in Example 2. Subsequently, a piezoelectric thin film 404 and an upper electrode film 405 were formed. As the piezoelectric thin film 404, lead zirconate titanate (PZT) having a rhombohedral crystal structure was used in Example 2.
It was produced under the same conditions as described above. As a result, a (111) plane oriented PZT film in which the polarization axis was preferentially oriented perpendicular to the substrate surface was obtained on the (100) Si single crystal substrate. Note that, regardless of the orientation of the crystal plane of the Si single crystal substrate, the (111) plane orientation P
A ZT film was obtained. The upper electrode film 405 was manufactured under the same conditions as 402. After patterning 405 by sputter etching under the same conditions as 402, patterning 404 was performed under the same conditions as the tetragonal PZT process shown in Table 2 (FIG. 8A).

Further, the diaphragm film 406 is connected to the upper electrode film 40.
5 (FIG. 8B). As 406, Ni
A Cr thin film was produced by a high-frequency magnetron sputtering method. The thickness was the same as that of the piezoelectric thin film 404. The film forming conditions were as follows: the substrate temperature was 200 ° C., the sputtering gas was Ar gas, the gas pressure was 0.8 Pa, and the high frequency input power density was 2.5.
W / cm ² (13.56 MHz). The diaphragm film 406 is preferably made of a metal material having a high Young's modulus, such as Pt, Cr, or Al. However, there is no problem with an insulator such as a SiO2 film, a resin film, or a photoresist. There is no problem even if the diaphragm film and the electrode film are made of the same material.

Subsequently, the film-forming substrate portion located below the piezoelectric thin film 404 was removed by chemical etching through the etching hole 403 provided in the lower electrode film (FIG. 8C). Etching removal of Si single crystal substrate
The test was performed using a mixed solution of hydrofluoric acid, nitric acid, and acetic acid. Next, the line segments α-α ′, β-β ′, γ-γ ′,
By cutting at δ−δ ′ and ε−ε ′, a cantilevered detection unit structure was manufactured in a lump (FIG. 8).
(E)). Finally, after the film formation substrate 401 is bonded and fixed to the circuit substrate 408, each electrode is connected to a bonding wire 411.
And the metal stem 413 and the cap 414 were sealed by welding (FIG. 8 (f)). 409, 410
Reference numeral 408 denotes a field-effect transistor for impedance conversion and a resistor mounted on the transistor 408.

Although the Si substrate has been exemplified as the film formation substrate 401, if an MgO substrate is used as the 401, the piezoelectric detector having the structure shown in the fourth embodiment can be manufactured by the same process as the third embodiment. Furthermore, it is clear that other film-forming substrates, such as a stainless metal substrate, are also effective in the present invention as long as they can be etched.

In the present invention, the beam structure of the detecting section is composed of only the piezoelectric thin film, the upper and lower electrode films, and the diaphragm film. Therefore, since the thickness of the entire beam structure is small, the spring constant of the beam structure can be reduced. Therefore, it is effective in that even small vibration and acceleration can be detected with high sensitivity.

In the present invention, the diaphragm film is formed directly on the piezoelectric thin film. Therefore, since it is not necessary to bond the piezoelectric thin film and the diaphragm, variation in sensitivity can be reduced, which is effective in improving reliability.

Furthermore, in the present invention, since the polarization axis of the piezoelectric thin film is oriented perpendicular to the surface of the film-forming substrate, high piezoelectric characteristics can be expected without performing the polarization treatment.
This is effective in increasing the sensitivity of the detector.

In the present invention, the detector structure is formed by etching. Therefore, compact integration is possible, and it is also possible to create a detector in which a plurality of beam structures are arranged in parallel or two-dimensionally.

Although the piezoelectric materials specified in Table 1 were used in Examples 1 to 4, it is clear that the present invention is effective for other piezoelectric thin film materials. Example 1
In (3) and (3), a (100) MgO single-crystal substrate was used as a film-forming substrate, and in Examples 2 and 4, a (100) Si single-crystal substrate was used. However, it is clear that the material of the film-forming substrate is not limited to these. .

In the first to fourth embodiments, the field effect transistor and the resistor for impedance conversion are arranged in the same cap as the detector. However, it is clear that arranging the field effect transistor and the resistor outside the sealing cap is also effective in the present invention. Further, the field effect transistor can be omitted depending on the capacitance of the piezoelectric detector.

[0058]

As described above, according to the present invention, since the piezoelectric body is a thin film material, it is possible to perform fine processing, and it is possible to easily form a detector having minute and various shapes. This is effective in that it is possible to achieve integration and to enable integration of the detector.

In the present invention, the diaphragm film is a film material directly formed on a film-forming substrate or a piezoelectric thin film. Therefore, in the manufacturing process, a bonding step between the diaphragm and the piezoelectric thin film is not required, and the variation in sensitivity due to the bonding step can be reduced, which is effective in improving reliability.

Further, even in the case of a single crystal substrate material from which a large substrate cannot be obtained, the area of the film formation substrate can be increased by a method of forming a film after fixing the film formation substrate to the detector substrate. Therefore, it is effective in increasing the throughput of the element manufacturing process, and is also effective in reducing the cost of the detector.

Furthermore, a beam-structured detector composed only of a piezoelectric thin film, an electrode film, and a diaphragm thin film is effective in that the beam structure has a small spring constant and can detect minute vibrations with high sensitivity. .

The orientation of the crystal structure of the piezoelectric thin film can be controlled, and the polarization axis can be oriented perpendicular to the surface of the film-forming substrate. Therefore, it is possible to detect the generated charges effectively. further,
By a film formation method such as a sputtering method, a piezoelectric thin film in which spontaneous polarization is aligned in one direction can be formed without performing polarization processing, and it is not necessary to perform polarization processing. Therefore, it is effective in that a thin film material having uniform piezoelectric characteristics can be prepared.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a piezoelectric detector according to a first embodiment. FIG. 1B is a plan view of a detection unit structure of the piezoelectric detector according to the first embodiment.

FIG. 2 is a cross-sectional view of a manufacturing process of the piezoelectric detector according to the first embodiment.

3A is a cross-sectional view of a piezoelectric detector according to a second embodiment. FIG. 3B is a plan view of a detection unit structure of the piezoelectric detector according to the second embodiment.

FIG. 4 is a cross-sectional view of a manufacturing process of the piezoelectric detector according to the second embodiment.

5A is a cross-sectional view of a piezoelectric detector according to a third embodiment. FIG. 5B is a plan view of a detection unit structure of the piezoelectric detector according to the third embodiment.

FIG. 6 is a cross-sectional view illustrating a manufacturing process of the piezoelectric detector according to the third embodiment.

7A is a cross-sectional view of a piezoelectric detector according to a fourth embodiment. FIG. 7B is a plan view of a detection unit structure of the piezoelectric detector according to the fourth embodiment.

FIG. 8 is a sectional view of a manufacturing process of the piezoelectric detector according to the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Deposition substrate 102 Lower electrode film 103 Piezoelectric thin film 104 Upper electrode film 105 Detector substrate 106 Concave shape part 107 External electrode lead-out hole 108 Detector electrode 109 Bonding wire 110 Field effect transistor 111 Resistance 112 Sealing cap 201 Film formation Substrate 202 Lower electrode film 203 Piezoelectric thin film 204 Upper electrode film 205 Detector substrate 206 Concave shape portion 207 Circuit substrate 208 Field effect transistor 209 Resistance 210 Bonding wire 211 Circuit substrate electrode 212 Stem 213 Sealing cap 301 Deposition substrate 302 Detection Substrate substrate 303 lower electrode film 304 etching hole 305 piezoelectric thin film 306 upper electrode film 307 diaphragm film 308 concave shape part 309 circuit board 310 field effect transistor 311 resistor 3 2 Bonding wire 313 Circuit board electrode 314 Stem 315 Sealing cap 401 Deposition substrate 402 Lower electrode film 403 Etching hole 404 Piezoelectric thin film 405 Upper electrode film 406 Vibration plate film 407 Recessed shape part 408 Circuit board 409 Field effect transistor 410 Resistance 411 Bonding wire 412 Circuit board electrode 413 Stem 414 Sealing cap

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Ryoichi Takayama 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Kazunari Nishihara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] In a detector substrate provided with a concave shape portion, a film forming substrate, a lower electrode film, a piezoelectric thin film, and an upper electrode film are provided on the concave shape portion, and the film forming substrate has an end portion. Has a cantilever beam fixed to the detector substrate or a beam fixed at both ends. 2. A detector substrate having a film-forming substrate attached thereto, wherein a lower electrode film, a piezoelectric thin film, an upper electrode film, and a diaphragm film are provided on the concave portion provided on the film-forming substrate;
A piezoelectric detector characterized in that the piezoelectric thin film has a cantilever whose end is fixed to a film-forming substrate or a fixed-end beam whose both ends are fixed. 3. A lower electrode film, a piezoelectric thin film, an upper electrode film, and a diaphragm film are provided on a concave portion provided on a film forming substrate, and the piezoelectric thin film has its ends fixed to the film forming substrate. A piezoelectric detector comprising a cantilever beam fixed at both ends or both ends fixed at both ends. 4. A step of forming a lower electrode film on a deposition substrate, a step of forming a piezoelectric thin film on the lower electrode film, a step of forming an upper electrode film on the piezoelectric thin film, Cutting the film-forming substrate on a detector substrate, and forming a cantilever or both-end fixed beam on the concave-shaped portion provided on the detector substrate, cutting the detector substrate and detecting the detector A method for manufacturing a piezoelectric detector, comprising a step of manufacturing a structure. 5. A step of forming a lower electrode film on a deposition substrate, a step of forming a piezoelectric thin film on the lower electrode film, a step of forming an upper electrode film on the piezoelectric thin film, Fixing on the detector substrate, disposing the piezoelectric thin film on the concave-shaped portion provided on the detector substrate, and cutting the film-forming substrate and the detector substrate to produce a detector structure. The manufacturing method of the piezoelectric detector characterized by the above-mentioned. 6. A step of bonding a film forming substrate on a detector substrate, a step of forming a lower electrode film on the film forming substrate bonded to the detector substrate, and forming a piezoelectric thin film on the lower electrode film. Forming the upper electrode film on the piezoelectric thin film, forming the diaphragm film on the upper electrode film, and etching the lower electrode film from the front side where the piezoelectric thin film is formed. Forming a concave portion by etching away a film-forming substrate portion located below the piezoelectric thin film, and cutting a film-forming substrate and a detector substrate to form a detection unit structure. Manufacturing method of a piezoelectric detector. 7. A step of forming a lower electrode film on a deposition substrate, a step of forming a piezoelectric thin film on the lower electrode film, a step of forming an upper electrode film on the piezoelectric thin film, A step of forming a diaphragm film thereon, and removing a film-forming substrate portion located under the piezoelectric thin film from the front side on which the piezoelectric thin film is formed through an etching hole provided in the lower electrode film by etching to form a concave shape portion. A method of manufacturing a piezoelectric detector, comprising the steps of: forming a substrate; and cutting a film-forming substrate to produce a detection unit structure. 8. The method according to claim 1, wherein the polarization axis of the piezoelectric thin film is oriented perpendicular to the surface of the film-forming substrate.
Or the piezoelectric detector according to 3.