JP2003046160A - Piezoelectric element, actuator, and ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for forming a piezoelectric element having superior piezoelectric characteristics on a board other than a single crystal board and a device using the same. SOLUTION: A piezoelectric element 1 is equipped with a piezoelectric film 2 of PZT, a lower electrode 3 and an upper electrode 4 sandwiching the piezoelectric film 2 between them, and a base film 5 of PLT which is interposed between the piezoelectric film 2 and the lower electrode 3 and about 50 to 200 nm in thickness. The piezoelectric element 1 is provided on a board 6 such as a polycrystalline stainless steel board, an amorphous heat-resistant glass board, or a single crystal silicon board. A piezoelectric element having superior piezoelectric characteristics can be formed on a board other than a single crystal board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element having a piezoelectric layer, and an actuator and an inkjet head using the piezoelectric element.

[0002]

2. Description of the Related Art Conventionally, piezoelectric materials have been used in various devices according to their purposes. Examples of such devices include an actuator configured to apply a voltage to a piezoelectric body to cause deformation according to the voltage, and conversely, an acceleration sensor and an angular velocity sensor that generate a voltage from the deformation of the piezoelectric body. .

As a piezoelectric material, a lead-based dielectric having excellent piezoelectric characteristics, particularly Pb (Zr _1-x Ti _x ) O ₃
A perovskite type ferroelectric substance, which is abbreviated as PZT, having a composition represented by is widely used. Conventionally, a piezoelectric element is made by cutting a sintered body of piezoelectric material obtained by heat treatment,
It is formed by forming a piezoelectric layer having a shape suitable for the purpose by a process such as polishing, and then providing a pair of electrodes on each of two opposing surfaces of the piezoelectric layer.

In recent years, it has been considered to apply various devices to micromachines, microsensors, etc. by further miniaturizing various devices using these piezoelectric elements, improving their functionality, and reducing power consumption (low voltage drive). Has been done, and in various fields that were previously considered impossible,
It is expected that minute and precise control will become possible.

Therefore, in addition to the conventional manufacturing method utilizing sintering, cutting, polishing, etc., a piezoelectric thin film is formed on a substrate and the fine processing technology used in the semiconductor process or the like is used to obtain more results. Research is being conducted to develop highly accurate ultra-compact piezoelectric elements. However, in miniaturizing the piezoelectric element, it is necessary to generate a minute displacement in the piezoelectric film with high accuracy and high efficiency, or to detect a minute displacement with high accuracy and high efficiency. Many are left.

[0006]

By the way, the technique of forming a piezoelectric film on a substrate (thinning process) is
Although it is a technique that is excellent in precision, functionality, and workability, it is performed in a completely different process from the conventional fine forming technique using a sintered body. Therefore, it is necessary to realize the structures of the piezoelectric body and the piezoelectric element that are suitable for the thinning process. The CVD method, the sputtering method, and the sol-gel method are generally used as a method for producing a thin film piezoelectric body having good piezoelectric characteristics. Even when these methods are used, it is difficult to obtain good characteristics unless the PZT thin film is epitaxially grown using a single crystal substrate such as a MgO single crystal substrate or a SrTiO ₃ single crystal substrate. It was Also, in order to obtain stable piezoelectric characteristics,
On the single crystal substrate, (Pb, La) TiO ₃ , PbTi
It was necessary to form a piezoelectric film such as O ₂ . As the single crystal substrate, a MgO single crystal substrate, a SrTiO ₃ single crystal substrate, or the like is used.

However, MgO single crystal substrate and SrTiO ₃
Since a single crystal substrate and the like are very expensive and the size of the substrate is about 30 mm × 30 mm, a substrate having a large area cannot be obtained. On the other hand, a technique for forming a piezoelectric film having good piezoelectric characteristics on a substrate other than a single crystal substrate has not yet been established.

An object of the present invention is to realize a technique for forming a piezoelectric film having good piezoelectric characteristics without using a single crystal substrate, thereby providing an inexpensive and high-performance piezoelectric element and various devices using the same. To provide.

[0009]

A piezoelectric element of the present invention is a piezoelectric element provided on a substrate, wherein a substrate having a thickness in the range of 50 nm or more and 200 nm or less and the substrate is sandwiched therebetween. And a piezoelectric film provided so as to be opposed to.

From this, it has been confirmed that a piezoelectric film having good piezoelectric characteristics can be obtained regardless of the material of the substrate on which the underlying film is formed.

By further comprising a first electrode interposed between the base film and the substrate, when the substrate is an insulator, the first application of voltage to the piezoelectric body is performed. Even if the substrate is a conductor,
The first electrode can have a function of suppressing the reaction between the base film and the substrate.

By further including the second electrode provided so as to face the base film with the piezoelectric film interposed therebetween, it is possible to apply a voltage to the piezoelectric body by the second electrode.

Since the substrate is made of a polycrystal or an amorphous material, an expensive material such as a single crystal is not used, and the piezoelectric is formed on a flexible substrate. It is also possible to directly form the element. Therefore, by applying this piezoelectric element to an actuator, it is possible to obtain an actuator having a small size, high functionality, and low power consumption.

The base film is preferably made of an oxide having a cubic or tetragonal crystal structure.

It is more preferable that the underlayer film is composed of a perovskite oxide containing no Zr as a constituent element, and in particular, a PLT which is a perovskite oxide having a composition represented by (Pb, La) TiO _3. By being constituted by, it is possible to exert a remarkable effect.

The piezoelectric film is preferably composed of a perovskite oxide containing Pb, Zr and Ti.

The actuator of the present invention comprises a fixing member,
A movable member movable with respect to the fixed member; and a piezoelectric element connected to the fixed member and the movable member, wherein the piezoelectric element has a base film having a thickness of 50 nm or more and 200 nm or less; And a piezoelectric film formed in contact with the base film.

As a result, a piezoelectric film having good piezoelectric characteristics can be obtained regardless of the material of the substrate on which the underlying film is formed, so that a highly accurate and highly functional actuator using this piezoelectric element can be obtained. And by making this actuator smaller, more sophisticated, and lower in power consumption, it has become possible to apply it to micromachines and microsensors.

The fixed member is attached to the moving member, the piezoelectric element is in contact with only the moving member, and the base film is interposed between the piezoelectric film and the moving member. Therefore, the piezoelectric element can have a structure further including an upper electrode provided on the piezoelectric film.

In this case, the piezoelectric element further has a lower electrode interposed between the base film and the moving member, so that when the moving member is an insulator,
The voltage can be applied to the piezoelectric body by the first electrode, and even when the moving member is a conductor, the first electrode can be provided with the function of suppressing the reaction between the base film and the moving member. it can.

The piezoelectric element is in contact with the moving member and the fixed member, and the base film is interposed between one of the moving member and the fixed member and the piezoelectric film. It is also possible to adopt the structure which has.

In this case, since the piezoelectric element further has the first electrode interposed between the base film and the one member, the above-described operation and effect can be exhibited. .

It is preferable that the piezoelectric element further has a second electrode interposed between the base film and the other of the moving member or the fixed member.

Since at least one of the movable member and the fixed member is made of a flexible polycrystalline body or amorphous body, the functionality of the actuator can be enhanced.

It is preferable that the base film is made of a perovskite oxide containing no Zr as a constituent element.

The ink jet head of the present invention comprises a head body having a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink.
A vibrating plate is provided so as to close the concave portion of the head main body to form a pressure chamber together with the concave portion, and a piezoelectric element provided on a surface facing the surface of the vibrating plate in contact with the pressure chamber. In the inkjet head, the piezoelectric element is provided between an upper electrode facing the vibrating plate, a piezoelectric film provided between the vibrating plate and the upper electrode, and between the vibrating plate and the piezoelectric film. And a base film having a thickness of 50 nm or more and 200 nm or less.

This makes it possible, for example, to provide a piezoelectric element having a piezoelectric film having good piezoelectric characteristics on the diaphragm regardless of the material of the diaphragm. Therefore, it is possible to reduce the size of the head body of the inkjet head and reduce the manufacturing cost of the inkjet head.

It is preferable to further include a lower electrode provided between the diaphragm and the base film.

Further, since the vibrating plate is composed of a polycrystalline body or an amorphous body, it is possible to use a flexible vibrating plate and form the piezoelectric element directly thereon. It will be possible.

A polycrystalline film or an amorphous film provided between the lower electrode and the vibration plate may be further provided.

The diaphragm is preferably made of metal.

The base film is preferably made of an oxide having a cubic or tetragonal crystal structure. More preferably, the underlying film is made of a perovskite oxide that does not contain Zr as a constituent element.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a sectional view showing a structure of a piezoelectric element according to a first embodiment of the present invention. The piezoelectric element 1 of this embodiment has a thickness of 0.1 μm.
˜50 μm piezoelectric film 2, lower electrode 3 and upper electrode 4 which are a pair of electrodes sandwiching piezoelectric film 2, and the thickness interposed between piezoelectric film 2 and lower electrode 3 is approximately 50 nm to 200
nm base film 5. The entire piezoelectric element 1 is provided on a substrate 6 such as a polycrystalline stainless steel substrate, an amorphous heat-resistant glass substrate, or a single crystal silicon substrate.

2A to 2E are cross-sectional views showing the manufacturing process of the semiconductor thin film element in this embodiment.

First, in the step shown in FIG. 2A, a thickness of 50 n is formed on the substrate 6 by using a sputtering method or an evaporation method.
A Pt film 3x for the lower electrode having a thickness of m to 200 nm is formed.

Next, in the step shown in FIG. 2B, the Pt film 3
A substrate PLT film 5x having a thickness of 50 nm to 200 nm is formed on x by a sputtering, CVD or sol-gel method under the condition of a substrate temperature of 500 ° C. to 700 ° C.

Next, in the step shown in FIG. 2C, a PZT film 2x for a piezoelectric film having a thickness of 0.1 μm to 50 μm is formed on the PLT film 5x by using the sputtering, CVD or sol-gel method. To form. Furthermore, a thickness of 50 nm is formed on the PZT film 2x by sputtering or vapor deposition.
~ 300nm upper electrode platinum (Pt) or gold (A
A noble metal film 4x such as u) is formed.

Next, in the step shown in FIG. 2D, a lithography step is performed to form a resist film 9 on the noble metal film 4x.

Then, in the step shown in FIG. 2E, the noble metal films 4x and PZ are formed using the resist film 9 as an etching mask.
The T film 2x, the PLT film 5x and the Pt film 3x are patterned to form the piezoelectric element 1 including the lower electrode 3, the base film 5, the piezoelectric film 2 and the upper electrode 4. This step is performed according to the following procedure.

First, the noble metal film 4x is etched to form the upper electrode 4. As an etching method, there are a dry etching method, a wet etching method, and the like. In the case of the dry etching method, etching is performed using argon gas (Ar). On the other hand, in the case of wet etching, gold (Au) is etched using a mixed solution of potassium iodide (KI), iodine (I ₂ ) and water (H ₂ O).

After the upper electrode 4 is formed, the resist film 9 is once removed and a resist film serving as an etching mask for the PZT film 2x is formed again. At this time, if the upper electrode 4 has the same shape as the PZT film and the resist film 9 for the upper electrode 4 is also excellent in wet etching resistance, the resist film 9 for the upper electrode 4 is left as it is.
It may be used as an etching mask at the time of x patterning.

Then, the PZT film 2x and the PLT film 5x are etched to form the piezoelectric film 2 and the base film 5.
At that time, a dry etching method is used when the film thickness of the PZT film 2x or the like is thin, and a wet etching method is used when the film thickness is thick. In the case of the dry etching method, etching is performed using argon gas (Ar) as in the case of gold (Au) or platinum (Pt). In the case of wet etching, etching is performed using an ammonium fluoride solution and hydrofluoric acid. As the etching method, the buffered hydrofluoric acid placed in a beaker is warmed to about 60 ° C. and the substrate 6 is immersed therein. Buffered hydrofluoric acid is constantly stirred to maintain a constant concentration. When the etching is completed, it is washed with pure water and then dried.

After that, the resist film used for etching the PZT film 2x and the like is removed, a resist film serving as an etching mask for forming the lower electrode is formed again, and the Pt film 3x is etched to form the lower electrode 3. To do. At that time, in the case of the dry etching method, etching is performed using argon gas (Ar). On the other hand, in the case of wet etching, a mixed solution of potassium cyanide, ammonium peroxosulfate and water is used as an etching solution.

According to this embodiment, the following effects can be exhibited.

Conventionally, (Pb, La) TiO ₃ (PL
T), PbTiO ₂ etc.
It is necessary to form a base film such as a PLT film having a thickness of 5 nm to 30 nm using a single crystal substrate such as an O single crystal substrate or a SrTiO ₃ single crystal substrate, and PZ is formed on the base film.
A piezoelectric film such as a T film was epitaxially grown. However, since the MgO single crystal substrate and the SrTiO ₃ single crystal substrate are very expensive, it is difficult to reduce the cost of the piezoelectric element. In addition, the size of the substrate is 30 mm ×
Since the thickness is about 30 mm, a large-area substrate cannot be obtained.

On the other hand, in the piezoelectric element and the manufacturing method thereof according to the present embodiment, a piezoelectric film having excellent piezoelectric characteristics is formed as described later, while using a relatively inexpensive substrate such as stainless steel, glass and Si. Therefore, a piezoelectric element having excellent characteristics can be obtained at low cost.

In addition, since there are many polycrystals and amorphous bodies which are flexible unlike monocrystals,
By directly forming a piezoelectric element on a stainless steel plate or the like that is a component of various actuators, it is possible to realize a piezoelectric actuator that is small in size, has high functionality, has low power consumption, and performs a minute operation.

-Example- In order to confirm the effect of this embodiment, the piezoelectric constants of the following specific samples were measured. In the sample having the structure shown in FIG. 1, the material of the substrate 6 is changed, and the thickness of the base film 5 made of PLT is 25 nm, 50 nm, 75 n.
m, 100 nm, 125 nm, 150 nm, 175n
The change state of the piezoelectric constant d ₃₁ with respect to the change of the thickness of the underlayer film was examined by changing to eight kinds of m and 200 nm.

As the substrate 6, MgO single crystal substrate, silicon single crystal substrate, stainless steel substrate (polycrystalline material), polysilicon substrate, heat-resistant glass substrate (amorphous material), titanium substrate (polycrystalline material), iron plate ( Polycrystal), copper plate (polycrystal),
A nickel plate (polycrystal) was used.

The lower electrode 3 is made of Pt having a thickness of 100 nm.
A film, the base film 5 composition Pb _{0. 85} La _0.15 Ti
_The piezoelectric film 2 is a PLT film expressed by _0.9625 O _x , and the piezoelectric film 2 is a PZT film whose composition is expressed by PbZr _0.5 Ti _0.5 O ₃ and has a thickness of 3 μm. The base film 5 and the piezoelectric film 2 are formed by sputtering at a substrate temperature of 600 ° C. The upper electrode 4 is a 200 nm-thick Au film formed by vapor deposition.

FIG. 3 is a perspective view schematically showing a method for measuring a piezoelectric constant using a laser displacement meter in this experiment. The piezoelectric element 1 and the substrate 6 are cut out in a strip shape of 3 mm × 15 mm, and one end portion in the length direction is fixed to the fixing base 7. That is, with the piezoelectric element 1 and the substrate 6 supported in a cantilevered state, a voltage was applied between the upper electrode and the lower electrode, and the displacement was measured using a laser displacement meter (not shown). Here, as the laser displacement meter, a laser Doppler displacement meter manufactured by Graphtec Co. was used.

Here, in the coordinate system shown in FIG. 3, when the piezoelectric element 1 extends in the X direction, the voltage is v (V), the thickness of the piezoelectric film 2 is t ₁ (m), and the thickness of the substrate 6 is T ₂ (m),
When the length of the piezoelectric film 2 is 1 (m), the mechanical coupling coefficient S ₁ of the piezoelectric film 2, the mechanical coupling coefficient of the substrate 6 is S ₂ , and the piezoelectric constant of the piezoelectric film 2 is d ₃₁ , the piezoelectric element 1 The elongation dx in the X direction is expressed by the following formula (1) dx = −3d ₃₁ · S ₁ · S ₂ · t ₁ (t ₁ + t ₂ ) · l / (S ₁ ² · t ₂ ⁴ + 4S ₁ · S ₂ · t ₁ · t ₂ ³ + 6S ₁ · S ₂ · t ₁ ² · t ₂ ² + 4S ₁ · S ₂ · t ₂ · t ₁ ³ + S ₂ · 2t ₁ ⁴ ) (1) Therefore, the value of each constant is substituted into equation (1) were calculated piezoelectric constant d _31.

FIG. 4 is a diagram showing data of the piezoelectric constant d ₃₁ when various types of substrates are used and the thickness of the base film is changed to 8 types. As shown in FIG. 4, not only a MgO single crystal substrate but also a polycrystalline substrate or an amorphous substrate is used.
It was found that a relatively good piezoelectric constant d ₃₁ can be obtained when the thickness of the base film 5 is 50 nm or more and 200 nm or less. Particularly, when the thickness of the base film 5 is 100 nm or more, 150 n
In the range of m or less, the piezoelectric constant d ₃₁ is extremely high, and MgO
It was found that the amount of decrease in the piezoelectric constant d ₃₁ with respect to the value when the substrate was used (about 80 × 10 ⁻¹² m / V) was slight.

That is, it is understood that the piezoelectric element and the manufacturing method thereof according to the present embodiment can form a piezoelectric element having excellent characteristics while using a relatively inexpensive substrate such as stainless steel, glass, and Si.

Here, conventionally, even if a piezoelectric film is formed using a substrate (polycrystalline substrate or amorphous substrate) other than a single crystal substrate, good piezoelectric characteristics have not been obtained. It is considered that, like the formation of the piezoelectric film on the crystal substrate, the thickness of the base film was no more than about 30 nm. On the other hand, in the present invention, the thickness of the base film is 50 nm or more and 200
It has been found that by setting the thickness to be not more than nm, a piezoelectric film having good orientation and piezoelectric characteristics can be formed on a polycrystalline substrate or an amorphous substrate.

Since the piezoelectric film can be formed on a substrate other than the single crystal substrate, when the piezoelectric element is provided on the actuator or various devices, it becomes possible to directly provide the piezoelectric element on the members of the actuator or various devices. It was For example, on the stainless steel spring of the actuator,
It is apparent from the manufacturing process of FIGS. 2A to 2D that the lower electrode, the base film, the piezoelectric film, the upper electrode and the like can be formed. Therefore, compared with the method of using an expensive single crystal substrate (MgO substrate) as a consumable item as in the case of using the conventional transfer method, the cost is reduced by eliminating the need for the single crystal substrate and simplifying the process. Can be reduced.

However, the transfer method can also be used in the present invention. For example, the piezoelectric element may be formed on an inexpensive polysilicon substrate and then the polysilicon substrate may be removed. Even in that case, since the polysilicon substrate is much cheaper than the MgO substrate,
The manufacturing cost can be reduced.

In that case, a single crystal silicon wafer can also be used. Even a single crystal substrate may not have good lattice matching with a piezoelectric film having a perovskite structure. In the case of such a substrate, a substrate having good lattice matching with the piezoelectric film having a perovskite structure (for example, A thin base film such as a MgO substrate (thickness: 3 nm to
30 nm) and a piezoelectric film is formed on a thin undercoating film, good characteristics cannot be obtained. However, as in the present invention, on a undercoating film with a thickness in the range of 50 nm to 200 nm. Further, by forming the piezoelectric film, a piezoelectric element having good piezoelectric characteristics can be obtained.

Here, in the present invention, the piezoelectric film 2 is
The piezoelectric material preferably has a perovskite structure, and particularly includes perovskite oxide containing lead (Pb), titanium (Ti) and zirconium (Zr), barium (Ba), and titanium (Ti). More preferably, it is composed of a perovskite oxide.

In the present invention, the lower electrode 3 is preferably a metal material which can withstand an oxidizing atmosphere when forming an oxide such as perovskite, and particularly platinum (Pt),
More preferably, it is composed of a metal selected from palladium (Pd), iridium (Ir) and ruthenium (Ru) or an oxide thereof.

In the present invention, the base film 5 is preferably an oxide material having a tetragonal or cubic crystal structure suitable for growing a perovskite film, and in particular, Z
It is preferably made of an oxide material having a perovskite structure that does not contain r. Specifically, preferable materials include lead titanate (PbTiO ₃₎ and was added to lanthanum _{PbTiO 3 (Pb, La) TiO} 3 ( hereinafter, simply referred to as PLT). In addition, magnesium oxide (Mg
O), strontium titanate (SrTiO ₃ ), barium titanate (BaTiO ₃ ), strontium ruthenate (SrRuO ₃ ), nickel oxide (Ni
O), cobalt oxide (CoO), titanium oxide (T
Oxides having a cubic or tetragonal crystal structure such as iO ₂ ), zinc oxide (ZnO), and zirconium oxide (ZrO ₂ ) can also be used as the material for forming the base film.

The thickness of the base film 5 is preferably 50 nm or more and 200 nm or less. As shown in FIG. 4, when the thickness of the base film 5 is less than 50 nm, it is considered that the orientation is not good, but the piezoelectric film 2 formed on the base film 5 has a sufficiently large piezoelectric coefficient. Because I can't get it. It is also known that when the thickness of the base film 5 exceeds 200 nm, the rigidity of the base film 5 becomes too high, but the piezoelectric coefficient of the piezoelectric film 2 deteriorates. Further, as shown in FIG. 4, in order to exert the best piezoelectric characteristics, the thickness of the base film 5 is more preferably 100 nm or more and 150 nm or less.

In the present invention, the upper electrode 4 is preferably made of a metal material that can withstand an oxidizing atmosphere, and particularly platinum (Pt), palladium (Pd), iridium (I
More preferably, it is composed of a metal selected from r), ruthenium (Ru) and gold (Au) or an oxide thereof.

In the present invention, it is preferable to use a substrate other than a single crystal substrate as the substrate 6. For example, when the materials are generally classified into three categories, that is, a single crystal body, a polycrystalline body, and an amorphous body, the substrate of the present invention is preferably a polycrystalline body or an amorphous body. Specific materials preferable for forming the substrate 6 are as follows. First
Include metals such as iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), tantalum (Ta), titanium (Ti), and chromium (Cr), and one or more of these metals. Alloys or oxides of these metals or alloys. Examples of these alloys or oxides include stainless steel, titanium alloys and heat resistant glass. Another preferable material for forming the substrate 6 is a semiconductor containing carbon (C) or silicon (Si) as a main component, or an oxide thereof.

However, by applying the present invention even to a single crystal substrate having a poor lattice matching with the piezoelectric film,
A piezoelectric element having good piezoelectric characteristics can be obtained.

-Other Examples- FIG. 5 shows piezoelectric materials when various substrates are used, an amorphous silicon film is formed on the substrates, then a base film is formed, and the thickness of the base film is changed to eight types. is a diagram showing experimental data of constant d _31. The thickness of the amorphous silicon film is about 3
It is 00 nm and is formed by the CVD method. Here, the thickness of the base film 5 made of PLT is 25 nm, 50
nm, 75 nm, 100 nm, 125 nm, 150 n
m, 175 nm, and 200 nm.

As the substrate 6, MgO single crystal substrate, stainless steel substrate (polycrystalline body), silicon substrate (single crystalline body and polycrystalline body), heat resistant glass substrate (amorphous body), titanium substrate (polycrystalline body). , Iron plate (polycrystal), copper plate (polycrystal),
A nickel plate (polycrystal) was used.

The lower electrode 3 is a Pt film having a thickness of 100 nm.
The composition of the base film 5 is Pb._0.85La _0.15Ti_0.9625O_x 
The piezoelectric film 2 has a composition of PbZ.
r_{0. Five}Ti_0.5 O₃ With a PZT film with a thickness of 3 μm
is there. The base film 5 and the piezoelectric film 2 have a substrate temperature of 600 ° C.
It is formed by sputtering. The upper electrode 4 is steam
It is an Au film having a thickness of 200 nm formed by deposition.

The piezoelectric element 1 and the substrate 6 are 3 mm × 15 m
It is cut out in a strip shape of m and is supported by a cantilever as shown in FIG. 3, and a voltage is applied between the upper electrode and the lower electrode to displace using a laser displacement meter (not shown). Was measured.

As shown in FIG. 5, even in the case of this example, M
Not only gO single crystal substrates, but also polycrystalline substrates and amorphous substrates
Even if a plate is used, the thickness of the base film 5 is 50 nm or more.
Relatively good piezoelectric constant d in the range of 200 nm or less₃₁But
It turned out to be obtained. In particular, the thickness of the base film 5 is 10
In the range of 0 nm or more and 150 nm or less, the piezoelectric constant d ₃₁
Is extremely high, and the value when using a MgO substrate (about 80 ×
10^-12piezoelectric constant d for m / V)₃₁The amount of decrease in
It is.

That is, according to the piezoelectric element and the method of manufacturing the same of the present invention, even when an amorphous silicon film or the like is provided on a relatively inexpensive substrate such as stainless steel, glass, or Si, the piezoelectric characteristic It can be seen that a good piezoelectric element can be formed.

FIG. 6 shows an experiment of the piezoelectric constant d ₃₁ when various substrates were used, a polycrystalline silicon film was formed on the substrate, then a base film was formed, and the thickness of the base film was changed to 8 types. It is a figure which shows data. The thickness of the polycrystalline silicon film is about 3
It is 00 nm and is formed by the CVD method. Here, the thickness of the base film 5 made of PLT is 25 nm, 5
0nm, 75nm, 100nm, 125nm, 150n
m, 175 nm, and 200 nm.

As the substrate 6, MgO single crystal substrate, stainless steel substrate (polycrystalline body), silicon substrate (polycrystalline body),
A heat-resistant glass substrate (amorphous body), a titanium substrate (polycrystalline body), an iron plate (polycrystalline body), a copper plate (polycrystalline body), and a nickel plate (polycrystalline body) were used.

The lower electrode 3 has a thickness of 100 nm to 120 nm.
Of the Pb film and the composition of the base film 5 is Pb _0.85 La _0.15 T.
i _0.9625 O _x is a PLT film, and the piezoelectric film 2 has a composition of PbZr _0.5 Ti _0.5 O ₃ and a thickness of 3 μm.
Of the PZT film. The base film 5 and the piezoelectric film 2 are formed by sputtering at a substrate temperature of 600 ° C. The upper electrode 4 is made of Au and has a thickness of 200 nm.
It is a film.

The piezoelectric element 1 and the substrate 6 are 3 mm × 15 m
It is cut out in a strip shape of m and is supported by a cantilever as shown in FIG. 3, and a voltage is applied between the upper electrode and the lower electrode to displace using a laser displacement meter (not shown). Was measured.

As shown in FIG. 6, even in the case of this example, M
Not only gO single crystal substrates, but also polycrystalline substrates and amorphous substrates
Even if a plate is used, the thickness of the base film 5 is 50 nm or more.
Relatively good piezoelectric constant d in the range of 200 nm or less₃₁But
It turned out to be obtained. In particular, the thickness of the base film 5 is 10
In the range of 0 nm or more and 150 nm or less, the piezoelectric constant d ₃₁
Is extremely high, and the value when using a MgO substrate (about 80 ×
10^-12piezoelectric constant d for m / V)₃₁The amount of decrease in
It turned out to be

That is, it is understood that the piezoelectric element and the method for manufacturing the same according to the present invention can form a piezoelectric element having good piezoelectric characteristics while using a relatively inexpensive substrate such as stainless steel, glass, and Si.

FIG. 7 shows a piezoelectric constant d when a stainless substrate is used, a base film is formed on the stainless substrate, and the Zr composition ratio in the PZT film, which is the piezoelectric film formed thereon, is changed. It is a figure which shows the experimental data of ₃₁ .

Here, PZT (PbZr _x Ti _1-x O
The Zr composition ratio x of ₃ ) is changed to 7 types in the range of 0.40 to 0.60. The thickness of the piezoelectric film (PZT film) is about 3 μm. As the substrate 6, a stainless substrate (polycrystal) and a MgO single crystal substrate were used.

The lower electrode 3 is a Pt film having a thickness of 100 nm.
The composition of the base film 5 is Pb._0.85La _0.15Ti_0.9625O_x 
PLT film with a thickness of about 100 nm to 120 nm
And the base film 5 and the piezoelectric film 2 have a substrate temperature of 600 ° C.
Is formed by sputtering. The upper electrode 4
It is an Au film having a thickness of 200 nm formed by vapor deposition.

The piezoelectric element 1 and the substrate 6 are 3 mm × 15 m
It is cut out in a strip shape of m and is supported by a cantilever as shown in FIG. 3, and a voltage is applied between the upper electrode and the lower electrode to displace using a laser displacement meter (not shown). Was measured.

As shown in FIG. 7, when a stainless steel substrate was used, it was almost constant even when the composition ratio x of PZT varied between 0.40 and 0.60, and a MgO single crystal substrate was used. It was found that a good piezoelectric constant d ₃₁ almost equal to that in the case was obtained.

That is, it is understood that the piezoelectric element and the manufacturing method thereof according to the present invention can form a piezoelectric element having good piezoelectric characteristics while using a relatively inexpensive substrate such as stainless steel, glass, and Si.

FIG. 8 is a diagram showing experimental data of the piezoelectric constant d ₃₁ when a stainless substrate is used and the material of the base film formed on the stainless substrate is changed to 10 types.

Here, the composition of the base film 5 is Pb._0.85L
a_0.15Ti_0.9625O_x PLT, magnesia oxide
Um (MgO), strontium titanate (SrTiO 3
₃ ), Barium titanate (BaTiO 3₃ ), SrRuO
₃ (Strontium ruthenate), Nickel oxide
(NiO), cobalt oxide (CoO), titanium oxide
Tan (TiO₂ ), Zinc oxide (ZnO), oxidation
Zirconium (ZrO ₂ ) 10 types
It In addition, the thickness of the base film 5 is 25 nm, 50 nm, 75
nm, 100 nm, 125 nm, 150 nm, 175n
8 kinds of m and 200 nm are used.

The piezoelectric film 2 is a PZT film (PbZr _0.5 Ti _0.5) having a thickness of 3 μm formed by sputtering.
O ₃ film).

The lower electrode 3 is a Pt film having a thickness of 100 nm to 120 nm formed by sputtering, and the base film 5 is a PLT film having a composition of Pb _0.85 La _0.15 Ti _0.9625 O _x and a thickness of about 100 nm to 120 nm. Yes,
The base film 5 and the piezoelectric film 2 are formed by sputtering at a substrate temperature of 600 ° C. The upper electrode 4 is a 200 nm-thick Au film formed by vapor deposition.

The piezoelectric element 1 and the substrate 6 are 3 mm × 15 m
It is cut out in a strip shape of m and is supported by a cantilever as shown in FIG. 3, and a voltage is applied between the upper electrode and the lower electrode to displace using a laser displacement meter (not shown). Was measured.

As shown in FIG. 8, if the base film is cubic or tetragonal, the base film 5 has a thickness of 50 nm or more and a thickness of 200.
It was found that a relatively good piezoelectric constant d ₃₁ can be obtained in the range of nm or less. In particular, the thickness of the base film 5 is 100 nm
As described above, it was found that the piezoelectric constant d ₃₁ was extremely high in the range of 150 nm or less.

That is, it is understood that the piezoelectric element and the manufacturing method thereof according to the present invention can form a piezoelectric element having good piezoelectric characteristics.

(Second Embodiment) FIGS. 9A to 9D.
[FIG. 8] A sectional view showing various structures of a piezoelectric actuator according to a second embodiment of the present invention.

The actuator of this embodiment has, as basic elements, the piezoelectric element 1, the reinforcing member 14 made of synthetic resin and provided to hold the piezoelectric element, and the reinforcing member 1.
4, an upper electrode lead electrode 16 that fills the through hole 17 formed in the reinforcing member 14 and is connected to the upper electrode 4 of the piezoelectric element 1, and an object 18 driven by the piezoelectric element 1. It has and. Further, the reinforcing member 14 connects the fixed portion 15, the object 18 and the piezoelectric element 1 to each other, and has a portion that functions as a moving member and a portion that functions as a fixed member.

The piezoelectric element 1 has the structure as described in the first embodiment, and includes the lower electrode 3, the base film 5 formed on the lower electrode 3, and the base film 5 on the base film 5. The formed piezoelectric film 2 and the upper electrode 4 formed on the piezoelectric film 2.
It has and. The material and thickness of each of the elements 2 to 5 forming the piezoelectric element 1 can be appropriately selected within the range described in the first embodiment. As a typical example, the lower electrode 3 is a Pt film having a thickness of 100 nm, and the base film 5 has a thickness of 1 expressed by Pb _0.85 La _0.15 Ti _0.9625 O _x.
It is a 50 nm PLT film, and the composition of the piezoelectric film 2 is PbZ.
The upper electrode 4 is a PZT film having a thickness of 3 μm and represented by r _0.5 Ti _0.5 O ₃ , and the upper electrode 4 is an Au film having a thickness of 200 nm.

Then, one end of the piezoelectric element 1 is fixed to the fixing portion 15 via the lower electrode 3. The lower electrode 3 is connected to the voltage supply unit through the fixing unit 15 when the fixing unit 15 is a conductor, and is fixed when the fixing unit 15 is an insulator.
5 is provided with a lead wire to be connected to the voltage supply unit. In the upper electrode 4, since the reinforcing member 14 is an insulating layer, the upper electrode lead wire 16 passes through the through hole 17.
Connected to. At the end of the piezoelectric element 1 opposite to the end in contact with the fixed portion 15, an object 18 to be operated by the piezoelectric element 1 is provided.
Is attached.

In the structure shown in FIG. 9A, the substrate used to form the piezoelectric element 1 is removed by a method such as etching. Then, only the reinforcing member 14 has a shape retaining function.

In the structure shown in FIG. 9B, the substrate used for forming the piezoelectric element 1 is removed by a method such as etching, and the lower electrode of the piezoelectric element 1 is located in the region where the substrate is removed. 3 is provided with a protective layer 19. The protective layer 19 and the reinforcing member 14 have a shape retaining function.

In the structure shown in FIG. 9C, the substrate used for forming the piezoelectric element 1 is thinly processed by a part 15a by a method such as etching. Then, the reinforcing member 14 and the part 15a of the substrate have a shape retaining function.

In the structure shown in FIG. 9D, the substrate used for forming the piezoelectric element 1 is removed by a method such as etching, the reinforcing member 14 covers the entire piezoelectric element 1, and the fixing portion is formed. It extends to the top of 15. This structure is an example of a structure in which it is desired to directly apply a voltage to the lower electrode 3 even if the fixing portion 15 is an insulator or the fixing portion 15 is a conductor. FIG. 9D shows a case where the fixing portion 15 is a conductor. In this case, the lower electrode lead wire 20 is provided on the portion of the reinforcing member 14 located on the fixing portion 15.
To form. When the fixing portion 15 is an insulator, the lower electrode lead wire 20 can be formed on the fixing portion 15 without forming the portion of the reinforcing member 14 located above the fixing portion 15.

10A to 10E are sectional views showing a part of the manufacturing process of the actuator of this embodiment.

First, in the step shown in FIG. 10A, the Pt film 3x to be the lower electrode 3 is formed on the substrate 10 which can be the fixing portion 15 or the object 18 by the method described in the first embodiment. Then, a PLT film 5x to be the base film 5, a PZT film 2x to be the piezoelectric film 2, and a noble metal film 4x to be the upper electrode 4 are formed.

Next, in the step shown in FIG. 10B, a lithography step is performed to form a resist mask 11 on the noble metal film 4x.

Next, in the step shown in FIG. 10C, the noble metal film 4x, the PZT film 2x, the PLT film 5x and the Pt film 3x are patterned to form the lower electrode 3, the base film 5,
The piezoelectric element 1 having the piezoelectric film 2 and the upper electrode 4 is formed. The patterning method at this time is as described in the first embodiment.

Next, in the step shown in FIG. 10D, a reinforcing member 14 made of synthetic resin is formed on the substrate 10 and the upper electrode 4 by using a spinner method, a roll method, a dipping method, a spray method, an ink jet method or the like. Apply to. Then, the reinforcing member 1 is subjected to a lithography process and an etching process.
A through hole 17 for drawing out the upper electrode 4 is opened at 4.

Next, in the step shown in FIG. 10E, the through hole 17 is filled with plating and the reinforcing member 14 is formed.
After forming a metal film such as an aluminum alloy covering the above, the metal film is patterned to form the upper electrode lead-out wiring 16.

The steps shown in FIGS. 10A to 10E are similar to those shown in FIG.
This is a method for realizing any of the structures shown in (a) to (c).

That is, in the structure shown in FIG. 10E, when the portion of the substrate 10 located below the piezoelectric element 1 is removed except for both ends thereof, the structure shown in FIG. Is obtained. That is, the substrate 10 is separated into the fixed portion 15 and the object 18.

In the structure shown in FIG. 10 (e),
The portion of the substrate 10 located below the piezoelectric element 1 is
When the protective layer 19 is formed after removing only the both ends, the structure shown in FIG. 9B is obtained.

Further, in the structure shown in FIG. 10 (e), the portion of the substrate 10 located below the piezoelectric element 1 is half-etched except for both ends thereof, as shown in FIG. 9 (c). The structure is obtained.

It should be noted that Japanese Unexamined Patent Application Publication No.
By adopting the method disclosed in 1-309673, the structure shown in FIG. 9D can be easily obtained.

FIG. 11 is a perspective view showing the basic structure of a two-stage actuator for an information recording / reproducing apparatus which is an example of the actuator of the second embodiment of the present invention. 12
(A), (b) is a front view and a plan view of this two-stage actuator, respectively.

As shown in FIGS. 11 and 12 (a), the head support mechanism has a slider 24 for flying or sliding on a recording medium on which a head element 23 is mounted and which rotates or runs.
The suspension 25 supporting the suspension 25, the base plate 26 fixing the suspension 25, the load beam (not shown) for applying a load to the slider 24, and the head element 23 are electrically connected to the recording / reproducing circuit of the information recording apparatus. Signal system (not shown). The two-stage actuator is directly or indirectly connected to the printed circuit by the signal system lead wire or suspension.

The micro-actuated actuator is integral with the suspension 25 and is arranged between the slider 24 to which the head element 23 is attached and the base plate 26.

This actuator has a base material of about 10
It is made of stainless steel having a thickness of up to 30 μm and a piezoelectric film that constitutes the minute driving element 28. The minute driving element 28 including the piezoelectric element has a bending structure so as to be perpendicular to the disk surface 29.

Further, as shown in FIG. 12 (b), the minute driving element 28 has a surface perpendicular to the disk surface 29 and a surface along the center line Lce in the longitudinal direction of the suspension 25, respectively.
It is configured to form an angle of 5 degrees or more.

FIGS. 13A and 13B are plan views for explaining the movement of the suspension and the like by the minute driving element. A drive voltage having a 90-degree opposite phase is applied to each of the minute drive elements 28, and expansion and contraction are repeated. The suspension 25 and the slider 24 and head element 23 fixed to the suspension 25 by expansion and contraction are shown in FIG.
Rotate as shown in (a). Further, when the drive voltage is reversed in phase, the suspension 25, the slider 24 fixed to the suspension 25, and the head element 23.
Rotates in the opposite direction, as shown in FIG. 13 (b).

The micro-driving element 28 is arranged so as to form an angle of about 15 or more with respect to the surface perpendicular to the disk surface (center line Lce shown in FIG. 12A). This is to reduce the influence of the rotation of the disk on the slider 24 (air viscous friction force) when the angle is small (about 0 to less than 15 degrees). With the above configuration, highly accurate track positioning becomes possible.

Although stainless steel was used as the base material for the actuator in this structure, any material can be used as long as it has spring properties and heat resistance and can secure a certain degree of rigidity even if it is thin. good.

Here, in the case of the actuator of the present embodiment, in the conventional structure, after the piezoelectric element 1 is formed on a single crystal substrate such as MgO, it is processed by photolithography and fixed by a transfer process. It was transcribed to the site. At the time of the transfer, the piezoelectric element 1 and the supporting member were fixed to each other using an adhesive or a metal joint. However,
Fixing using an adhesive or metal bonding complicates the process. Moreover, there is a possibility that a positional error may occur when the piezoelectric element 1 is fixed, an inclination with respect to the mounting surface, or the like.

On the other hand, in the present embodiment, the first
According to the method described in the embodiment, it becomes possible to directly form the piezoelectric element 1 on a flexible metal plate such as a stainless plate or an insulating plate (polycrystalline body or amorphous body). There is no need to perform transfer by adhesion or metal bonding. Therefore, it is possible to reduce the manufacturing cost by eliminating the need for a separately expensive single crystal substrate such as an MgO substrate, reduce the manufacturing cost by simplifying the process, and improve the mechanical accuracy and function. In particular, it is possible to realize an actuator that is downsized, highly functionalized, and has low power consumption, and it is possible to provide an actuator suitable for a micromachine or a microsensor.

The actuator of the present invention can be mounted on various devices as described below, for example.

The actuator functions as an optical device as follows (1) A device using a device for deflecting light, for example,
Printer, projection display, barcode reader,
Scanner etc. (2) Thin film actuated mirror array (3) Micro optical element: optical switching element, focus adjustment device, variable focus mirror, etc. (4) Aperture device: optical equipment such as camera, video movie, endoscope (5) ) There is a mirror that can be changed.

The actuators functioning as pumps include the following (6) inkjet printers (7) ion generators: air purifiers, humidifiers, and dust collectors.

The actuators functioning as motors include the following (8) optical pickups and ultrasonic motors used in piezoelectric linear motors.

There are the following (9) oscillation element (10) discriminator (11) filter as a function of the actuator as a piezoelectric resonator.

The actuator functions as a sensor as follows (12) Pressure sensor (13) Acceleration sensor (14) Impact sensor (15) AE sensor (Acoustic Emission) (16) Ultrasonic sensor (17) Angular velocity sensor (18) There is a gravity sensor.

The actuator constitutes a part of the mechanism as follows (19) Micro relay (20) Ultra thin film keyboard (21) Fluid control valve (22) Hard disk drive (HDD) actuator.

(Third Embodiment) In this embodiment, an example of a piezoelectric actuator used in an HDD will be described as an application example of the actuator in the second embodiment.

14 (a) and 14 (b), respectively,
It is a perspective view showing the whole 1st generation piggyback actuator structure concerning this embodiment, and a perspective view showing the partial structure of the head part of the 2nd generation piggyback actuator.

As shown in FIG. 14A, the first-generation piggyback actuator includes a main actuator having a VCM (voice coil motor) 30 as a driving means and an auxiliary actuator having a piezoelectric element 1 as an auxiliary driving means. It is a first-generation piggyback actuator that is equipped with the main actuator and auxiliary actuator to position-control the magnetic head 34. A plurality of piezoelectric elements 1 are mounted on one upper surface of the suspension 35 formed of a stainless plate, and are arranged substantially at the center of gravity of the actuator mechanism. The same number of branch ends 31 as the piezoelectric elements 1 are provided on the upper surface of each piezoelectric element 1.
A support arm 31 having a is attached, and the tip of the support arm 31 is connected to a suspension 32. A slider 33 having a magnetic head 34 is attached to the tip of the suspension 32.
Then, the plurality of branch ends 31a are finely driven by the piezoelectric element 1. That is, each branch end 31a of the support arm 31 is simultaneously and minutely driven by the piezoelectric element 1,
The fine movement of the magnetic head 34 is adjusted.

As shown in FIG. 14B, the second-generation piggyback actuator is a main actuator using the VCM 30 shown in FIG.
4 (b) is provided with a suspension 32 connected to a main actuator via a support arm (not shown) and a slider 33 having a magnetic head 34 attached to its tip. The piezoelectric element 1 for finely controlling the slider 33 is provided between the suspension 32 and the slider 33.

The piezoelectric element 1 has the structure as described in the first embodiment, and includes a lower electrode, a base film formed on the lower electrode, and a piezoelectric film formed on the base film. It has a body film and an upper electrode formed on the piezoelectric film. The material and thickness of each element constituting the piezoelectric element 1 are
It can be appropriately selected within the range described in the first embodiment. As a typical example, the lower electrode has a thickness of 100 n.
m is a Pt film, and the base film has a composition of Pb _0.85 La _0.15 T
i _0.9625 O _x is a PLT film having a thickness of 150 nm, the piezoelectric film is a PZT film having a composition of PbZr _0.5 Ti _0.5 O ₃ and a thickness of 3 μm, and the upper electrode has a thickness of 20
It is a 0 nm Au film.

Conventionally, in the case of a piezoelectric actuator as shown in FIGS. 14A and 14B, in the conventional structure, the piezoelectric element 1 is formed on a single crystal substrate such as MgO and then photolithography is performed. Used for processing and transferred to a fixed site using a transfer process. At the time of the transfer, the piezoelectric element 1 and the support arm 3 are formed by using an adhesive or a metal joint.
1 is fixed, the piezoelectric element 1 and the suspension 32 are fixed, or the piezoelectric element 1 and the slider 33 are fixed. However, in the case of the structure shown in FIG. 14B, the size of the slider 33 is as small as a few mm or less, so that the fixing area is also very small. It is very difficult to separate and. Furthermore, when using metal bonding,
The work on the process becomes complicated. Moreover, there is a possibility that a positional error may occur when the piezoelectric element 1 is fixed, an inclination with respect to the mounting surface, or the like.

On the other hand, in the present embodiment, the first
According to the method described in the embodiment, it becomes possible to directly form the piezoelectric element 1 on the stainless steel plate.
There is no need to bond or metal bond on one side. Therefore, it is possible to reduce the manufacturing cost by eliminating the need for a separately expensive single crystal substrate such as an MgO substrate, reduce the manufacturing cost by simplifying the process, and improve the detection or recording accuracy by improving the mechanical accuracy and the function. Can be achieved.

(Fourth Embodiment) In this embodiment, an example in which the piezoelectric element 1 of the present invention is applied to an ink jet head will be described.

FIGS. 15 (a) and 15 (b) show an XV shown in FIG. 17 of the ink jet head according to the fourth embodiment of the present invention.
FIG. 5 is a cross-sectional view taken along line XV and a partially enlarged view thereof. Figure 1
FIG. 6 is a sectional view taken along line XVI-XVI shown in FIG. 17 of the inkjet head according to the fourth embodiment of the present invention.
FIG. 17 is a plan view of an inkjet head according to the fourth embodiment of the present invention.

As shown in FIGS. 15 to 17, the ink jet head of this embodiment has a plurality of pressure chamber recesses 52 having a supply port 52a for supplying ink and a discharge port 52b for discharging ink. The head main body 51 is formed. Each recess 52 of the head body 51
Are opened in a substantially rectangular shape on one outer surface (upper surface) of the head main body 51 and are arranged in one direction at a predetermined interval. In addition, in FIG. 17, each recess 52 (a nozzle hole 6 described later)
4, the vibration plate 72, the piezoelectric element 73, the upper electrode 4 and the like), only three are described in order to avoid complication.
In reality, many are provided.

The side wall of each recess 52 of the head main body 51 is
An ink flow path component 56 composed of a pressure chamber component 55 made of photosensitive glass having a thickness of about 200 μm, and the bottom wall portion of each recess 52 is fixed to the pressure chamber component 55 and a plurality of stainless steel thin plates are bonded together. It is composed of. In the ink flow path component 56, a supply ink flow path 57 connected to the supply port 52a of each recess 52 and a discharge ink flow path 58 connected to each discharge port 52b are formed. There is. Each supply ink flow path 57 is connected to an ink supply chamber 60 extending in the direction in which the recesses 52 are arranged, and the ink supply chamber 60 includes the pressure chamber component 55 and the ink flow channel component 56.
Is connected to an ink supply hole 61 that is formed in the above and is connected to an ink tank (not shown). On the surface (lower surface) of the ink flow path component 56 that faces the surface in contact with the pressure chamber component 55,
A nozzle plate 63 of a polymer resin such as polyimide having a thickness of about 20 μm is provided, and the nozzle plate 63 is provided with nozzle holes 64 having a diameter of about 20 μm which are connected to the respective ejection ink flow paths 58. . Each nozzle hole 64
Are arranged on a straight line extending in the arrangement direction of the recesses 52.

The pressure chamber component 55 of the head main body 51
A piezoelectric actuator 71 is provided on the surface (upper surface) opposite to the surface in contact with the ink flow path component 56. This piezoelectric actuator 71 is provided in a divided state for each pressure chamber 53 so as to close each recess 52 of the head main body 51 and form a pressure chamber 53 together with the recess 52. , And Ni, etc., has a vibration plate 72. Each of the diaphragms 72
It is formed in a substantially rectangular shape that is substantially the same as the pressure chamber 53 in a plan view, and is also electrically connected to each other by wiring (not shown), and also serves as a common electrode common to all piezoelectric elements 1 to be described later. Have

Further, the piezoelectric actuator 71 has a surface (upper surface) opposite to the surface of each vibration plate 72 in contact with the pressure chamber 53.
2 to 5 .mu.m each of which is provided in a portion corresponding to the pressure chamber 53 and is made of lead zirconate titanate (PZT).
The piezoelectric element 1 having a thickness of m and the vibrating plate 7 of each piezoelectric element 1.
The Pt upper electrode 4 having a thickness of 0.1 μm, which is provided on the surface (upper surface) opposite to the surface in contact with 2, and which applies a voltage to each piezoelectric element 1 together with the vibration plate 72.

The piezoelectric element 1 has the structure as described in the first embodiment, and includes the lower electrode 3, the base film 5 formed on the lower electrode 3, and the base film 5. The formed piezoelectric film 2 and the upper electrode 4 formed on the piezoelectric film 2.
It has and. The material and thickness of each element forming the piezoelectric element 1 can be appropriately selected within the range described in the first embodiment. As a typical example, the lower electrode 3
Is a Pt film having a thickness of 100 nm, and the base film 5 has a composition of P
b _0.85 La _0.15 Ti _{0.9625 Ox} thickness _150n represented by O _x
m PLT film, and the piezoelectric film 2 has a composition of PbZr _0.5.
A PZT film with a thickness of 3 μm represented by Ti _0.5 O ₃ ,
The upper electrode 4 is an Au film having a thickness of 200 nm. In the manufacturing process, after the lower electrode 3, the base film 5, the piezoelectric film 2 and the upper electrode 4 are formed on the flat metal plate, bending and patterning are performed to obtain the structure shown in FIG. Can be created.

The portion of each vibration plate 72 corresponding to the pressure chamber 53 is on the opposite side (upper side) from the side on which the pressure chamber 53 is arranged.
Curved in a convex shape. That is, the portion of each vibration plate 72 corresponding to the pressure chamber 53 has a substantially arcuate shape in both the cross section cut along the width direction of the vibration plate 72 and the cross section cut along the length direction. It projects to the side opposite to the chamber 53. As the vibration plates 72 are curved, the piezoelectric elements 1 and the upper electrodes 4 are also curved upward. It is preferable that the maximum amount of protrusion of the portion of each diaphragm 72 corresponding to the pressure chamber 53 to the side opposite to the pressure chamber 53 (the amount of protrusion of the substantially central portion of each diaphragm 72) is set to 0.05 to 10 μm. . This is because if the maximum protrusion amount is smaller than 0.05 μm, the effect of suppressing the defects of the vibration plate 72 and the piezoelectric element 1 cannot be sufficiently obtained during the production and use of the inkjet head as described later, while it is smaller than 10 μm. If it is large, on the contrary, cracks and the like are likely to occur in the diaphragm 72 and the piezoelectric element 1 during manufacturing. The more preferable range of the maximum convex amount is 0.05 to 5 μm.

Next, the operation of the ink jet head will be described. By applying a voltage between the vibrating plate 72 and the upper electrode 4, the volume of the pressure chamber 53 at the portion corresponding to the pressure chamber 53 of the vibrating plate 72 is reduced. The ink in the pressure chamber 53 is ejected from the ejection port 52b. That is, when a pulsed voltage is applied to the piezoelectric element 1 via the diaphragm 72 and the upper electrode 4, the rise of this pulse voltage causes the piezoelectric element 1 to contract in the width direction perpendicular to its thickness direction. Since the diaphragm 72 does not contract, the portion of the diaphragm 72 corresponding to the pressure chamber 53 is the pressure chamber 5
It is deformed so as to be displaced to the 3 side (to the side where the convex amount decreases). Due to this deformation, pressure is generated in the pressure chamber 53, and this pressure causes a predetermined amount of ink in the pressure chamber 53 to be discharged.
It is ejected to the outside (on the paper surface to be printed) from the nozzle hole 64 via b and the ejection ink flow path 58 and adheres to the paper surface in a dot shape. Then, the piezoelectric element 1 expands in the width direction due to the fall of the pulse voltage, and the diaphragm 72 returns to the original state. At this time, in the pressure chamber 53, from the ink supply chamber 60 to the supply ink flow path 57 and Supply port 52a
The ink is filled via the. Note that not only one color ink but also, for example, black, cyan, magenta, and yellow inks may be ejected from different nozzle holes 64 to perform color printing.

In the conventional manufacturing method, after the piezoelectric element is formed on the MgO substrate or the like, the piezoelectric element is transferred onto the vibration plate 72. Further, instead of the transfer method, it is possible to form the piezoelectric element directly on the vibration plate 72 by sputtering or the like, but in that case, the piezoelectric characteristics of the piezoelectric element were not so good.

On the other hand, in the present embodiment, the piezoelectric element 1 can be directly formed on the metal plate of stainless steel, Cr, Ni or the like by the method described in the first embodiment, which is separately expensive. It is possible to reduce the manufacturing cost by eliminating the need for a single crystal substrate such as a MgO substrate, reduce the manufacturing cost by simplifying the process, and improve the printing accuracy by improving the mechanical accuracy.

(Other Embodiments) In the above first to fourth embodiments, the substrate on which the piezoelectric element 1 is formed is made of a conductive material such as stainless steel, Cu, Ni, C.
In the case of a metal plate such as r, the piezoelectric element 1 does not need to include the lower electrode 3. This is because the substrate can function as the lower electrode. However, when the underlying film is actually a perovskite film such as a PLT film, some kind of barrier layer is necessary in order to prevent a reaction due to mutual diffusion between the underlying film and the material forming the substrate. Therefore, in the above embodiment, the Pt film is actually used as the lower electrode.

Similarly, when a conductive member is attached above the piezoelectric element 1, the conductive member can function as an upper electrode.

Furthermore, in the above-mentioned first to fourth embodiments, the lower electrode 3 and the substrate (the substrate 1 in the second embodiment are
0 or a diaphragm 72) in the fourth embodiment, a polycrystalline film such as a polycrystalline silicon film or an amorphous film may be interposed.

[0148]

According to the present invention, when the thickness is 50 nm or more, 2
Since the structure includes a base film having a thickness of 00 nm or less and a piezoelectric film provided on the base film, a piezoelectric element having good piezoelectric characteristics is provided even on a substrate that is a polycrystalline body or an amorphous body. As a result, it is possible to reduce the manufacturing cost and provide various devices using the piezoelectric element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a piezoelectric element that is a first embodiment of the present invention.

2A to 2E are cross-sectional views showing a manufacturing process of the semiconductor thin film element in the present embodiment.

FIG. 3 is a perspective view schematically showing a method for measuring a piezoelectric constant using a laser displacement meter in the experiment of the present invention.

FIG. 4 is a diagram showing data of piezoelectric constants d ₃₁ when various types of substrates are used and the thickness of a base film is changed to 8 types in the first embodiment of the present invention.

FIG. 5 is an example of the first embodiment of the present invention, in which various substrates are used, an amorphous silicon film is formed on the substrates, and then a base film is formed, and the thickness of the base film is changed to 8 types. is a diagram showing experimental data of the piezoelectric constant d ₃₁ of the case was.

FIG. 6 is a view showing that, in the example of the first embodiment of the present invention, various substrates are used, a polycrystalline silicon film is formed on the substrates, and then a base film is formed, and the thickness of the base film is changed to 8 types. is a diagram showing experimental data of the piezoelectric constant d ₃₁ obtained while.

FIG. 7 is a Zr composition in a PZT film that is a piezoelectric film formed by forming a base film on a stainless substrate using a stainless substrate in the example of the first embodiment of the present invention. is a diagram showing experimental data of the piezoelectric constant d ₃₁ when changing the ratio.

FIG. 8 is an experiment of the piezoelectric constant d ₃₁ when a stainless substrate is used and the material of the base film formed on the stainless substrate is changed to 10 kinds in the example of the first embodiment of the present invention. It is a figure which shows data.

9A to 9D are cross-sectional views showing various structures of a piezoelectric actuator according to a second embodiment of the present invention.

10A to 10E are cross-sectional views showing a part of the manufacturing process of the actuator of the second embodiment of the present invention.

FIG. 11 is a perspective view showing a basic configuration of a two-stage actuator which is an example of an actuator according to a second embodiment of the present invention.

12A and 12B are a front view and a plan view, respectively, of a two-stage actuator for an information recording / reproducing apparatus, in order.

13 (a) and 13 (b) are plan views for explaining movement of a suspension and the like by a minute driving element in a two-stage actuator.

14A and 14B are, respectively, a perspective view showing an overall structure of a first-generation piggyback actuator according to a third embodiment of the present invention, and a head portion of a second-generation piggyback actuator. It is a perspective view which shows a partial structure.

15A and 15B are a cross-sectional view and a partially enlarged view of the inkjet head according to the fourth embodiment of the present invention taken along line XV-XV shown in FIG.

16 is a cross-sectional view taken along line XVI-XVI shown in FIG. 17 of the inkjet head according to the fourth embodiment of the present invention.

FIG. 17 is a plan view of an inkjet head according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 Piezoelectric element 2 Piezoelectric film 3 Lower electrode 4 Upper electrode 5 Base film 6 substrate 7 fixed base

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 41/08 H01L 41/18 101D 41/18 101Z 41/187 41/08 D H02N 2/00 B41J 3/04 103A F Term (reference) 2C057 AF93 AG39 AG44 AG55 BA03 BA14 5D068 AA02 CC11 EE19 GG24 5D096 AA02 NN03 NN07

Claims (23)

[Claims] 1. A piezoelectric element provided on a substrate, comprising: a base film having a thickness of 50 nm or more and 200 nm or less; and a piezoelectric film provided facing the substrate with the base film interposed therebetween. A piezoelectric element comprising: 2. The piezoelectric element according to claim 1, further comprising a first electrode provided between the base film and the substrate. 3. The piezoelectric element according to claim 1, further comprising a second electrode provided so as to face the base film with the piezoelectric film interposed therebetween. 4. The piezoelectric element according to claim 1, wherein the substrate is made of a polycrystalline body or an amorphous body. 5. The piezoelectric element according to claim 1, wherein the base film is made of an oxide having a cubic or tetragonal crystal structure. Piezoelectric element. 6. The piezoelectric element according to claim 5, wherein the base film is made of a perovskite oxide containing no Zr as a constituent element. 7. The piezoelectric element according to claim 6, wherein the underlying film is composed of PLT which is a perovskite oxide having a composition represented by (Pb, La) TiO _3. element. 8. The piezoelectric element according to claim 1, wherein the piezoelectric film is composed of a perovskite oxide containing Pb, Zr, and Ti. element. 9. A fixed member, a moving member movable with respect to the fixed member, and a piezoelectric element connected to the fixed member and the moving member, wherein the piezoelectric element has a thickness of 50 nm or more and 200 nm or less. An actuator having a base film in the range of 1 and a piezoelectric film formed in contact with the base film. 10. The actuator according to claim 9, wherein the fixed member is attached to the moving member, the piezoelectric element is in contact with only the moving member, and the base film is the piezoelectric body. An actuator, wherein the piezoelectric element is interposed between a film and the moving member, and the piezoelectric element further has an upper electrode provided on the piezoelectric film. 11. The actuator according to claim 10, wherein the piezoelectric element further includes a lower electrode interposed between the base film and the moving member. 12. The actuator according to claim 9, wherein the piezoelectric element is in contact with the moving member and the fixed member, and the base film is one of the moving member and the fixed member, An actuator which is interposed between the piezoelectric film and the piezoelectric film. 13. The actuator according to claim 12, wherein the piezoelectric element further includes a first electrode interposed between the base film and the one member. . 14. The actuator according to claim 12 or 13, wherein the piezoelectric element includes a second electrode provided between the base film and the other member of the moving member and the fixed member. An actuator characterized by further comprising. 15. The actuator according to claim 9, wherein at least one of the moving member and the fixed member is a flexible polycrystalline body or amorphous body. An actuator comprising: 16. The actuator according to claim 9, wherein the underlayer film is made of a perovskite oxide that does not contain Zr as a constituent element. 17. A head main body having a pressure chamber recess having a supply port for supplying ink and a discharge port for discharging ink, and a recess for the head main unit for closing the pressure chamber together with the recess. In an ink jet head comprising a diaphragm provided to configure and a piezoelectric element provided on a surface of the diaphragm facing the pressure chamber, the piezoelectric element is provided on the diaphragm. The opposing upper electrode, the piezoelectric film provided between the vibrating plate and the upper electrode, and the thickness provided between the vibrating plate and the piezoelectric film having a thickness of 5
An ink jet head having a base film in a range of 0 nm or more and 200 nm or less. 18. The inkjet head according to claim 17, further comprising a lower electrode provided between the diaphragm and the base film. 19. The inkjet head according to claim 18, wherein the vibrating plate is made of a polycrystalline body or an amorphous body. 20. The inkjet head according to claim 18, further comprising a polycrystalline film or an amorphous film provided between the lower electrode and the vibrating plate. . 21. The ink jet head according to claim 19, wherein the vibrating plate is made of metal. 22. The ink jet head according to any one of claims 17 to 21, wherein the base film is made of an oxide having a cubic or tetragonal crystal structure. Inkjet head. 23. The inkjet head according to claim 22, wherein the base film is composed of a perovskite oxide that does not contain Zr as a constituent element.