JPH10290033A - Piezo-electric thin film element, and actuator and ink-jet type recording head using the thin film element and manufacture of piezo-electric thin film element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reduction of the oxygen concentration in a piezo-electric thin film and to improve the characteristics of a piezo-electric body in the process for forming the piezo-electric thin film element by performing heat treatment after the formation of a lower electrode and before the formation of the piezo-electric thin film under oxygen atmosphere. SOLUTION: A piezo-electric thin film element has a silicon substrate 11, a silicon oxide film 12 formed on the substrate 11, a titanium film 13 formed on the oxide film 12, a titanic-acid lead zirconate (PTZ) film 15 of the piezo-electric thin film formed on a lower electrode 14 and an upper electrode 16 formed on the film 15. Before the PTZ is annealed, the heat treatment of the lower electrode 14 is performed under the presence of oxygen. Thus, the oxygen in the piezo-electric thin film 15 is trapped in each grain boundary in the lower electrode 14. By the heat treatment of the lower electrode 14 under the oxygen atmosphere, the compound of the oxygen diffused into platium and Ti appears as round particles equally dispersed in the lower electrode 14. Therefore, the piezo-electric thin film 15 having the excellent characteristics of the piezo-electric body is obtained by preventing the reduction of the oxygen concentration in the piezo-electric thin film 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a piezoelectric thin film element. Further, the present invention relates to a piezoelectric thin film element obtained by using this manufacturing method, and an actuator using the same.

[0002]

2. Description of the Related Art This actuator converts electric energy into mechanical energy and vice versa, and is used for a pressure sensor, a temperature sensor, an ink jet recording head and the like. In an ink jet recording head, a piezoelectric thin film element is used as a vibrator serving as a driving source of ink ejection.

This piezoelectric thin film element generally has a structure including a piezoelectric thin film made of a polycrystalline body, and an upper electrode and a lower electrode arranged with the piezoelectric thin film interposed therebetween. . In general, the composition of the piezoelectric thin film is a two-component system containing lead zirconate titanate (hereinafter referred to as “PZT”) as a main component, or a three-component system obtained by adding a third component to this two-component PZT. It is a component system.

[0004] Piezoelectric thin films of these compositions can be prepared, for example, by sputtering, sol-gel, laser ablation, or C
It can be formed by a VD method or the like.

[0005] As an example of these, ferroelectrics using binary PZT are described in "Applied Physics Letters, 1991, Vol.
58, No. 11, pages 1161-1163 ". Also, JP-A-6-40035 and" Journal of The
American Ceramic Society, 1973, Vol. 56, No. 2, page
s 91-96 "discloses a piezoelectric body using binary PZT.

When the piezoelectric thin film element is applied to, for example, an ink jet recording head, the piezoelectric thin film element has a thickness of 0.4 μm to 20 μm.
A piezoelectric thin film (PZT film) having a thickness of about m is desired. Further, since a high piezoelectric strain constant is required for the piezoelectric thin film, it is generally necessary to perform a heat treatment at a temperature of 700 ° C. or more to grow crystal grains of the piezoelectric thin film.

[0007]

However, the present inventor has come to the knowledge that the heat treatment lowers the oxygen concentration in the piezoelectric thin film and deteriorates the piezoelectric strain constant. The inventor of the present invention has intensively studied the reason and obtained the following opinion. That is, platinum, which is used as the lower electrode of the piezoelectric thin film element, is rich in the property of adsorbing oxygen, as is clear from the fact that it is used as an oxidation catalyst.

[0008] Therefore, the lower electrode traps oxygen in the PZT when the PZT is sintered, and combines with the titanium diffused into the lower electrode.

In order to solve such a problem, the present invention prevents a decrease in the oxygen concentration in the piezoelectric thin film in the process of forming the piezoelectric thin film element, thereby providing a piezoelectric material having excellent piezoelectric characteristics. It is an object to provide a method for producing a thin film.

Another object of the present invention is to provide such a piezoelectric thin film. Still another object of the present invention is to provide
An object of the present invention is to provide an actuator having the piezoelectric thin film, particularly an ink jet recording head.

[0011]

In order to achieve this object, the present invention is to form an upper electrode and a lower electrode with a polycrystalline piezoelectric film interposed therebetween. In the method of manufacturing a piezoelectric thin film, wherein the piezoelectric body is formed and then heat-treated, heat treatment is performed in an oxygen atmosphere after the lower electrode is formed and before the piezoelectric thin film is formed. The oxygen atmosphere preferably has an oxygen partial pressure (by volume) of 60% or more. When the oxygen partial pressure is less than 100%, the other gas is, for example, nitrogen or argon.

Further, a piezoelectric thin-film element according to the present invention is a piezoelectric thin-film element comprising a polycrystalline piezoelectric film, and an upper electrode and a lower electrode disposed with the piezoelectric film interposed therebetween. Before forming a piezoelectric thin film on the lower electrode,
The lower electrode is formed by heat treatment in the presence of oxygen.

According to another aspect of the present invention, there is provided a piezoelectric thin-film element comprising: a polycrystalline piezoelectric film; and an upper electrode and a lower electrode disposed with the piezoelectric film interposed therebetween. In the device, the oxygen concentration ratio (r) of the piezoelectric thin film to the oxygen concentration in the piezoelectric thin film in the vicinity of the lower electrode is 0.9 to 1.2.
It is characterized in the following range. Here, the oxygen concentration (r) is displayed as follows. The neighborhood is, for example, 10
× 10 ^-9 m or less.

R = (oxygen concentration in the piezoelectric thin film / oxygen concentration in the piezoelectric film near the lower electrode) Further, the present invention relates to an actuator using the piezoelectric thin film element as a mechanical stress generating means. It is characterized by. Further, the invention is characterized in that it is an ink jet recording head provided with the actuator.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where a PZT film is formed as a piezoelectric film will be described.

(Embodiment 1) FIG. 1 is a sectional view showing the structure of a piezoelectric element according to the present invention. This piezoelectric thin-film element includes a silicon substrate 11, a silicon oxide film 12 formed on the silicon substrate 11, a titanium film (Ti / TiO ₂ / Ti) 13 formed on the silicon oxide film 12, and a lower electrode ( Ti / Pt)
A PZT film 15 formed on the PZT film 14 and an upper electrode 16 formed on the PZT film 15 are provided.

As described above, the lower electrode 14 is formed of platinum combined with a layer of titanium and titanium oxide during film formation. With the lower electrode 14 having such a configuration, the lattice constant of the lower electrode 14 and the lattice constant of the PZT film 15 can be close to each other.
Adhesion with the T film 15 can be improved.

The reason why the titanium layer made of (Ti / TiO ₂ / Ti) is formed on the silicon oxide film 12 is to enhance the adhesion between the silicon oxide film and the platinum layer. Furthermore, on platinum
The reason for forming Ti is to make the piezoelectric thin film into a columnar structure as described later.

The present inventors have further proposed that the characteristics of the piezoelectric material can be improved by making the crystal structure of the piezoelectric thin film a columnar structure. By forming titanium on platinum in an island shape, the crystal structure of the piezoelectric thin film can be adjusted to a structure that enhances the piezoelectric characteristics.

By the annealing performed after the PZT film is formed, the (Ti / TiO ₂ / Ti) of the titanium film becomes Pt or S
Nothing that diffuses into iO ₂ and forms a special layer on the lower electrode is observed even by a scanning electron microscope.

The PZT film 15 is made of a polycrystalline material, and the grain boundaries of the crystalline material are, as shown in FIGS.
And 16 in a direction substantially perpendicular to the plane. That is, the crystal grains of PZT have a columnar structure.

As the PZT film 15, a film mainly composed of a two-component system and a film mainly composed of a three-component system obtained by adding a third component to the binary system are preferably used. Binary PZT
Pb (Zr _x Ti _1-x ) O ₃ + YPbO (where 0.40 ≦ X ≦ 0.6, 0 ≦ Y ≦ 0.3)
Those having a composition represented by the following chemical formula:

Further, as a preferable specific example of the ternary PZT, a PZT having the composition represented by the following chemical formula, which is obtained by adding a third component to the above-mentioned two-component PZT, may be mentioned.

[0024] _{PbTi a Zr b (A g B} h) c O 3 + ePbO + (fMgO) n ( where, A is, Mg, Co, Zn, Cd , Mn , and N
a divalent metal selected from the group consisting of i or Sb,
Represents a trivalent metal selected from the group consisting of Y, Fe, Sc, Yb, Lu, In and Cr. B is Nb,
It represents a pentavalent metal selected from the group consisting of Ta and Sb, or a hexavalent metal selected from the group consisting of W and Te. A + b + c = 1, 0.35 ≦ a ≦ 0.5
5, 0.25 ≦ b ≦ 0.55, 0.1 ≦ c ≦ 0.4,
0 ≦ e ≦ 0.3, 0 ≦ f ≦ 0.15c, g = f = 1
/ 2, n = 0, provided that A is a trivalent metal,
And when B is not a hexavalent metal, and A is a divalent metal and B is a pentavalent metal, g is 1/3, h is 2/3, and A represents Mg and B represents Nb, and n represents 1. A more preferred specific example of a ternary system is lead magnesium niobate, that is, one in which A is Mg, B is Nb, g is 1/3, and h is 2/3.

Furthermore, in order to improve the piezoelectric characteristics of any of these binary PZT and ternary PZT, trace amounts of Ba, Sr, La, Nd, Nb, Ta,
Sb, Bi, W, Mo, Ca and the like may be added.
In particular, in a ternary system, 0.10 mol% or less of Sr, Ba
Is more preferable for improving the piezoelectric characteristics. In a three-component system, addition of Mn and Ni of 0.10 mol% or less is preferable because the sinterability is improved.

In the process of forming the piezoelectric thin film 15, a predetermined heat treatment is performed to obtain the structure as described above. According to the study by the present inventors, oxygen in PZT diffuses into the lower electrode during this heat treatment. As described later, it has been confirmed that when the lower electrode is formed by sputtering, the electrode has a columnar structure like PZT. In this crystal structure, oxygen tends to be trapped at the crystal grain boundaries, and titanium diffused in platinum forms an oxide at the crystal grain boundaries.

Therefore, the present inventor has set forth the following:
It has been proposed that the lower electrode be heat treated in the presence of oxygen before annealing PZT. FIG. 4 shows a cross section in the width direction of the piezoelectric thin film element formed by the method described below, and is a scanning microscope photograph obtained under the conditions of an acceleration voltage of 15 kV and an extraction voltage of 4.0 kV.

According to this, it can be seen that both the lower electrode and the piezoelectric film have the columnar crystal structure substantially as described above.
Oxygen in the piezoelectric thin film is trapped at each crystal grain boundary in the lower electrode. In addition, due to the heat treatment of the lower electrode in an oxygen atmosphere, the compound of oxygen and Ti diffused in the platinum appears as round particles uniformly dispersed in the lower electrode.

Next, a method for manufacturing a piezoelectric thin film element according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 5A to 5C are cross-sectional views showing the steps of manufacturing the above-described piezoelectric thin film element. In the step shown in FIG. 5A, thermal oxidation is performed on the silicon substrate 11 to form a silicon oxide film 12 having a thickness of about 0.3 to 1.2 μm on the silicon substrate 11. Next, by the sputtering method,
On the silicon oxide film 12, an overall thickness of 0.0
A titanium film 13 of about 1 μm to 0.04 μm made of Ti / TiO ₂ / Ti is formed. Next, the lower electrode 14 made of platinum is formed on the titanium film 13 by sputtering.
Is formed with a thickness of about 0.2 to 0.8 μm.

The sputtering conditions at this time are as follows. As a device, a DC sputtering device was used. The sputtering pressure condition is 0.4 Pa. The voltage condition is 1 kw for Pt, 200 w for Ti,
In the case of TiO ₂ , it is 300 w. The condition of the atmosphere gas is such that Pt and Ti are in argon, and TiO ₂ is O ₂ / Ar = 10/90.

Next, the element in the course of film formation is placed in a diffusion furnace and heated at 400 to 600 ° C. for 30 to 60 minutes in an oxygen atmosphere (oxygen partial pressure of 60% or more). Or RTA
(Rapid Thermal Annealing) Put this device in a furnace, and in an oxygen atmosphere (flow rate 5 L / min), temperature 400 to 600 ° C.
Then, heating is performed for 60 to 300 seconds.

Next, as in the step shown in FIG.
Titanium is formed in an island shape by sputtering on the lower electrode 14 formed in the step shown in FIG. By setting this titanium to a thickness of 40 to 60 angstroms, the crystal structure of the piezoelectric thin film can be strongly oriented to 100 planes.

Next, the PZT film 15 is formed thereon. This is performed, for example, by a sol-gel method. Here, it is assumed that PZT is manufactured by a multi-layer coating of eight coats using the sol-gel method. The sol-gel method is as follows.

This manufacturing method is a method in which a hydrated complex of a hydroxide of a metal component capable of forming the PZT film 15, that is, a sol is dehydrated into a gel, and the gel is heated and calcined to prepare an inorganic oxide. It is. This manufacturing method includes the following steps.

A. Step of Forming Sol Composition In this embodiment, the sol of the metal component forming the PZT film can be adjusted by hydrolyzing, for example, an acid with an alkoxide or acetate of a metal capable of forming the PZT film. In the present invention, the composition of the PZT film described above can be obtained by controlling the composition of the metal in the sol. That is, alkoxides or acetates of titanium, zirconium, lead, and other metal components are used as starting materials.

Here, there is an advantage that the composition of the metal component constituting the PZT film is substantially maintained before the PZT film (piezoelectric thin film) is finally formed. That is, there is very little change due to evaporation of the metal component, particularly the lead component, during the firing and annealing treatment, and therefore, the composition of the metal component in these starting materials matches the metal composition in the finally obtained PZT film. Will be. That is,
The composition of the gel is determined according to the piezoelectric film (PZT film in the present embodiment) to be formed.

Further, in this embodiment, in order to obtain a PZT film in which the lead component is excessive, the lead component in the sol is preferably up to 20 mol%, more preferably up to 15 mol%, than required from the stoichiometry. Preferably, it is excessive.

In the present embodiment, this sol is preferably used as a composition mixed with an organic polymer compound. The organic polymer compound absorbs the residual stress of the thin film during drying and baking, and effectively prevents the thin film from cracking. Specifically, when a gel containing the organic polymer is used, pores are generated in a gelled thin film described later. It is considered that these pores absorb the residual stress of the thin film in the pre-annealing and annealing steps described later. Here, as the organic polymer compound preferably used, polyvinyl acetate, hydroxypropyl cellulose, polyethylene glycol, polyethylene glycol monomethyl ether, polypropylene glycol,
Polyvinyl alcohol, polyacrylic acid, polyamide,
Examples include polyamic acid, acetylcellulose and derivatives thereof, and copolymers thereof.

In this embodiment, by adding polyvinyl acetate, a porous gel thin film having a large number of pores of about 0.05 μm is reduced to a size of 1 μm or less by adding hydroxypropylcellulose. And a porous gel thin film having a wide distribution can be formed.

In the present embodiment, polyethylene glycol having an average molecular weight of about 285 to 420 is preferably used. Further, as the polypropylene glycol, those having an average molecular weight of about 300 to 800 are preferably used.

In the manufacturing method according to the present embodiment, first,
This sol composition is applied on the lower electrode 14 (see FIG. 5B) on which the PZT film 15 is to be formed. The application method at this time is not particularly limited, and a method usually performed, for example,
Spin coating, dip coating, roll coating, bar coating and the like can be performed. Further, it can be applied by flexographic printing, screen printing, offset printing or the like.

The thickness of the film formed by the above coating is controlled so that the thickness of the porous gel thin film formed in the gelling step described below is 0.3 μm or less in consideration of the subsequent steps. It is preferable that the thickness be about 0.2 μm.

Next, the applied sol composition is dried naturally,
Alternatively, heat at a temperature of 200 ° C. or less. Here, the sol composition may be further applied on the dried (heated) film to increase the film thickness. In this case, the underlying film is desirably dried at a temperature of 80 ° C. or higher.

B. Step of gelling a film made of a sol composition Next, the film obtained in the step of forming a film of the sol composition is baked, and a porous gel made of an amorphous metal oxide substantially free of residual organic matter is formed. Form a thin film.

The calcination is carried out by heating the sol composition at a temperature and for a sufficient time to gel the film of the sol composition and to remove organic substances from the film. In this embodiment, the firing temperature is preferably set to 300 to 450 ° C.
More preferably, the temperature is set to 400 ° C.

The firing time varies depending on the temperature and the type of furnace used. For example, when a degreasing furnace is used,
It is preferably about 10 to 120 minutes, more preferably about 15 to 60 minutes. When a hot plate is used, it is preferably about 1 to 60 minutes, more preferably about 5 to 30 minutes.

Through the above steps, a porous gel thin film was formed on the lower electrode 14.

C. Pre-annealing step Next, the porous gel thin film obtained in the above-described step b is heated and baked to convert this film into a film made of a crystalline metal oxide film.

The calcination is performed at a temperature required to convert the porous gel thin film into a film made of a crystalline metal oxide.
It is not necessary to perform the process until the perovskite crystal occupies most of the crystal, and the process may be terminated when the gel thin film is uniformly crystallized. In this embodiment, the firing temperature is 40
The temperature is preferably in the range of 0 to 800 ° C, and more preferably in the range of 550 to 750 ° C. The firing time varies depending on the firing temperature and the type of furnace used. For example, when an annealing furnace is used, about 0.1 to 5 hours is preferable, and about 0.5 to 2 hours is more preferable. Also, R
When using a TA (Rapid Thermal Annealing) furnace,
It is preferably about 0.1 to 10 minutes, more preferably about 1 to 5 minutes.

In this embodiment, the pre-annealing step can be performed in two stages. Specifically, first, as a first step, annealing is performed at a temperature in the range of 400 to 600 ° C., and then, as a second step, 60 ° C.
Annealing can be performed at a temperature in the range of 0-800C. More preferably, as the first step, 450
Annealing can be performed at a temperature in the range of ５550 ° C., and then in a second stage at a temperature in the range of 600-750 ° C.

By this step, the porous gel thin film was converted into a film made of a crystalline metal oxide film.

D. Next, the steps a and b described above are repeated three more times, and four porous gel thin films are laminated. Then, the film is converted from a metal oxide film by the pre-annealing step of the step C. Next, island-shaped titanium is formed on the PZT in an island shape by the above-described method, and the above-described steps a and b are further repeated four times.

The number of laminated films obtained as a result of this repetition process may be appropriately determined in consideration of the final thickness of the PZT film 15. Here, the thickness is preferably 0.15 μm per layer. Needless to say, the film thickness is preferably such that cracks and the like do not occur in the next step (step e) described later.

In this repetitive process, a new porous gel thin film is formed on the previously formed film, and as a result of the subsequent pre-annealing, the newly formed porous gel thin film is substantially the same as the previously formed film. It becomes an integrated film.

Here, the substantially integrated film means not only a case where there is no discontinuous layer between the stacked layers but also a case where the finally obtained PZT film 15 according to the present embodiment is used. There may be a discontinuous layer between the laminated layers. When the steps a, b and c are further repeated, a new porous gel thin film is formed, and as a result of the subsequent pre-annealing, the new porous gel thin film is formed of the crystalline laminated film obtained above. And a substantially integrated film.

E. Next, a baking temperature of 600 to 120 is applied to the film obtained in the step d.
Annealing is performed at 0 ° C., more preferably at 800 to 1000 ° C. The firing time varies depending on the firing temperature and the type of furnace used. For example, when an annealing furnace is used, the firing time is preferably about 0.1 to 5 hours, more preferably about 0.5 to 2 hours. When an RTA furnace is used, about 0.1 to 10 minutes is preferable, and about 0.5 to 3 minutes is more preferable.

In this embodiment, the perovskite-type crystal growth step, that is, annealing can be performed in two stages. Specifically, in the first stage, 60
Annealing is performed at a temperature of about 0 to 800 ° C., and in a second stage, annealing is performed at a temperature of 800 to 1000 ° C. Also, more preferably, in the first stage, 600 to 750
Annealing is performed at a temperature of about 100 ° C.
Annealing can be performed at a temperature of ９950 ° C.

Through the above operation, PZT having a thickness of 1.2 μm and made of a columnar polycrystal grown with titanium as a nucleus is formed on the lower electrode 14.

Next, after the lower electrode is formed, the above-described heat treatment is performed prior to forming the piezoelectric thin film (the method of the present invention).
The comparison of the piezoelectric characteristics between the case where the same conditions are applied except that this is not performed (comparative method) is shown.

[0061] As described above, according to the method of the present invention, it is possible to obtain a piezoelectric thin film element having excellent piezoelectric characteristics as compared with the conventional method. In the piezoelectric thin film element obtained by the method of the present invention, the inventor has determined that the oxygen concentration in the piezoelectric thin film and the vicinity of the lower electrode 1
When the oxygen concentration in the piezoelectric film near 0 nm was compared,
The oxygen concentration in the piezoelectric film near the lower electrode was higher than that in the piezoelectric thin film, and it was confirmed that the ratio (r) was 0.95. The oxygen concentration in the piezoelectric film near the lower electrode was 35 atomic%.

The present inventors have made intensive studies and found that the ratio (r) of the two oxygen concentrations is preferably in the range of 0.9 to 1.2, and the oxygen concentration in the vicinity of the lower electrode was 30 to It is preferably in the range of 60 atomic%. On the other hand, in these characteristics of the conventional method, the ratio (r) was about 0.67, and unlike the present invention, a remarkable decrease in the oxygen concentration in the PZT film was observed. The measurement of the oxygen concentration was performed as follows.

The piezoelectric thin film was fragmented by a low-angle ion milling machine, and the composition was analyzed by TEM (transmission electron microscope). The equipment used and the low-angle ion milling were manufactured by Shahwan Fischtech Ant Hankley Linter Co., Ltd.
It is a FEG-CM200TEM manufactured by Phillip.
The applied voltage during XEDX observation by TEM was 200
kV.

The measurement results are data obtained by averaging four points, and are as follows.

[0065] (The unit of data is atomic%.) According to the present invention, the piezoelectric constant (d ₃₁ ) can be improved by 20 to 30% as compared with the conventional one.

The process shown in FIG. 5B is completed as described above, and the process shifts to a process shown in FIG. 5C. In this step, FIG.
The upper electrode 16 made of aluminum having a thickness of about 0.2 to 1.0 μm is formed on the PZT film 15 obtained in the step shown in FIG.

Thus, a piezoelectric thin film device as shown in FIG. 2 was obtained. In addition, it was confirmed that the obtained PZT film 15 did not have any cracks, and that the cross section did not have a layered discontinuous surface due to lamination.

FIG. 6 is a cross-sectional view showing one ink reservoir of an ink jet recording head using the piezoelectric thin film element according to the present invention as a vibrator.

As shown in FIG. 6, the ink jet recording head according to the third embodiment includes a silicon substrate 21 on which an ink reservoir 27 is formed, a vibration plate 22 formed on the silicon substrate 21, and a vibration plate 22. A lower electrode 23 formed at a desired position on the upper side and an ink reservoir 2 on the lower electrode 23
7, an upper electrode 25 formed on the piezoelectric thin film 24, and a second substrate 26 joined to the lower surface of the silicon substrate 21. ing.

The lower electrode 23 has the same configuration as the lower electrode described in the second embodiment. The piezoelectric thin film 24
Has the same configuration as the PZT film described in the first embodiment.

In the ink jet recording head, ink is supplied to the ink reservoir 27 via an ink channel (not shown). Here, when a voltage is applied to the piezoelectric film 24 via the lower electrode 23 and the upper electrode 25, the piezoelectric film 24 is deformed and pressure is applied to the ink in the ink reservoir 27. With this pressure, ink is ejected from a nozzle (not shown) to perform ink jet recording.

In this ink jet recording head, since the above-described piezoelectric thin film element having excellent piezoelectric characteristics is used as a vibrator, ink can be ejected with a large pressure.

[0073]

As described above, according to the method of manufacturing a piezoelectric thin film element according to the present invention, it is possible to prevent a decrease in the oxygen concentration in the piezoelectric thin film in the process of forming the piezoelectric thin film element. A piezoelectric thin film having excellent piezoelectric properties can be provided.

Further, according to the present invention, it is possible to provide a piezoelectric thin film having excellent piezoelectric properties by preventing a decrease in oxygen concentration in the piezoelectric thin film.

Further, according to the present invention, it is possible to provide an actuator having the piezoelectric thin film, particularly an ink jet recording head.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piezoelectric thin film element according to Embodiment 1 of the present invention.

FIG. 2 is a scanning electron microscope (SEM) photograph showing a cross section of a PZT film constituting the piezoelectric thin film element according to the first embodiment.

FIG. 3 is a scanning electron micrograph showing a plane of the PZT film shown in FIG. 2;

FIG. 4 is a scanning microscope (SEM) photograph showing a cross section of the piezoelectric thin film element obtained by the manufacturing process of the present invention.

FIGS. 5A to 5C are cross-sectional views illustrating a process of manufacturing the above-described piezoelectric thin film element.

FIG. 6 is a cross-sectional view showing one ink reservoir of an ink jet recording head using a piezoelectric thin film element according to the present invention as a vibrator.

[Explanation of symbols]

 11, 21 Silicon substrate 12 Silicon oxide film 13 Titanium oxide film 14, 23 Lower electrode 14B Titanium seed crystal 15 PZT film 16, 25 Upper electrode 22 Vibration plate 24 Piezoelectric thin film 26 Substrate 27 Ink pool

Claims (6)

[Claims] 1. A method of manufacturing a piezoelectric thin film, wherein an upper electrode and a lower electrode are formed with a piezoelectric film interposed therebetween, and the piezoelectric material is formed on the lower electrode and then heat-treated. A method for manufacturing a piezoelectric thin film, comprising performing a heat treatment in an oxygen atmosphere before forming a piezoelectric thin film. 2. The method according to claim 1, wherein the oxygen atmosphere has an oxygen partial pressure of 60% or more. 3. A piezoelectric thin film element comprising a polycrystalline piezoelectric film, and an upper electrode and a lower electrode disposed with the piezoelectric film interposed therebetween, wherein a piezoelectric thin film is formed on the lower electrode. A piezoelectric thin film element formed by subjecting the lower electrode to a heat treatment in the presence of oxygen before being formed. 4. A piezoelectric thin film device comprising: a piezoelectric film made of a polycrystalline body; and an upper electrode and a lower electrode disposed with the piezoelectric film interposed therebetween. A piezoelectric thin-film element, wherein the oxygen concentration ratio (r) of the piezoelectric thin film is in the range of 0.9 to 1.2. r = (oxygen concentration in piezoelectric thin film / oxygen concentration in piezoelectric film near lower electrode) 5. An actuator using the piezoelectric thin film element according to claim 3 as mechanical stress generating means. 6. An ink jet recording head comprising the actuator according to claim 5.