Thin-film piezoelectric material element, method of manufacturing the same, head gimbal assembly, hard disk drive, ink jet head, variable focus lens and sensor

A thin-film piezoelectric material element includes a lower electrode film, a piezoelectric material film, and an upper electrode film, the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially. An upper surface of the piezoelectric material film is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected, and the concave part is a curved surface concavely hollowed, the upper electrode film is formed on the concavity and convexity surface. The thin-film piezoelectric material element has a stress balancing film formed with a material having an internal stress capable of cancelling an element stress, the stress balancing film is formed on the upper electrode film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2014-198676, filed Sep. 29, 2014 and Japanese Patent Application No. 2014-239589, filed Nov. 27, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to a thin-film piezoelectric material element which has a piezoelectric material and electrodes having thin-film like shape and method of manufacturing the same, head gimbal assembly, hard disk drive, ink jet head, variable focus lens and sensor having the thin-film piezoelectric material element.

2. Related Background Art

A hard disk drive has a large recording capacity and is used as the heart of a storage device. The hard disk drive records and reproduces data to/from a hard disk (recording medium) by a thin-film magnetic head. A part, which the thin-film magnetic head is formed, is called as a head slider, and a part, which the head slider is mounted on the edge part, is a head gimbal assembly (will also be referred to as HGA).

Further, recording and reproducing of data to/from the recording medium is performed by flying the head slider from a surface of the recording medium while rotating the recording medium, in the hard disk drive.

On the other hand, it has become difficult to control a position of the thin-film magnetic head accurately by control with only a voice coil motor (VCM), because heightening a recording density of the recording medium has developed in company with increase of a capacity of the hard disk drive. Therefore formerly, a technology, which an actuator having supplementary function (a supplementary actuator) is mounted on the HGA in addition to a main actuator with the VCM, and the supplementary actuator controls a minute position that is not able to be controlled by the VCM, is known,

A technology, which the main actuator and the supplementary actuator control the position of the thin-film magnetic head, is also called two stage actuator system (dual-stage system).

In the two stage actuator system, the main actuator makes drive arms rotate to decide a position of the head slider on a specific track of the recording medium. Further, the supplementary actuator adjusts the position of the head slider minutely so that the position of the thin-film magnetic head may become an optimum position.

A micro actuator using a thin-film piezoelectric material element is known formerly as the supplementary actuator. The thin-film piezoelectric material element has a piezoelectric material and a pair of electrodes formed to sandwich the piezoelectric material, and each of them is formed to be a thin-film shape.

Further, for example, as disclosed in the JP 2003-101095 (referred to also as Patent Document 1), the thin-film piezoelectric material element having two layers structure, which two piezoelectric laminated materials including the piezoelectric material are overlaid, is known as the conventional thin-film piezoelectric material element.

The piezoelectric laminated material has a structure which the piezoelectric material and electrode films are formed on a substrate, and it sometimes cause a displacement (also referred to as crooked displacement) along the direction where it is not intended. Further, there is a problem which the piezoelectric laminated material has been curved even a condition which a voltage is not applied to, because stress of each film constituting the piezoelectric laminated material is not equal, or is not symmetrical along to the thickness direction. Accordingly, there is a problem which the piezoelectric laminated material is not able to be mounted on a desired position of the HGA, and the piezoelectric laminated material is broken when it is mounted on the HGA. However, if each piezoelectric laminated material is laminated so that the electrode films, of one pair of electrode films, connected to the outside, oppose each other, crooked displacement caused by each piezoelectric laminated material are canceled each other. Therefore, an effect, which crooked displacement in the whole thin-film piezoelectric material element is suppressed, is obtained. Further an effect, which the thin-film piezoelectric material element is mounted easily on the HGA without broken, is obtained due to canceling curve of each piezoelectric laminated material.

However, on the other hand, it is necessary for the thin-film piezoelectric material element having two layers structure to pile up the piezoelectric laminated material with adhesive. Therefore, there is a problem which both improvement of the mass production capability and lowering of the manufacturing cost are difficult in the thin-film piezoelectric material element having two layers structure.

Hence, conventional method, which a stress occurred between the piezoelectric material and the substrate is released at a manufacturing stage, thereby the crooked displacement and curve (or bowing) are able to be suppressed even the piezoelectric laminated material having single layer, is provided as the method of manufacturing the thin-film piezoelectric material element (see for example, P4897767 (referred to also as Patent Document 2)).

On the other hand, the piezoelectric laminated material having single layer is not able to avoid a generation of stress inside of the piezoelectric laminated material, because it needs a piling up of plurality of thin-films. Therefore, the piezoelectric material elements disclosed in the JP 2012-76387 (referred to also as Patent Document 3), JPH 11-87791 (referred to also as Patent Document 4) are known. The piezoelectric material elements, which electrode of one side has two layers structure and the outside of them is formed with material having small compressing stress than the inside one, so stress of the electrode entirely is relaxed, is disclosed in the Patent Document 3. Further, the piezoelectric material elements, having a structure which two piezoelectric materials are piled up sandwiching a relaxing layer, and two electrodes are arranged both side of the two piezoelectric materials, is disclosed in the Patent Document 4.

SUMMARY OF THE INVENTION

As mentioned in the above-described Patent Documents 2-4, there is a conventional proposal to try to suppress a stress in the piezoelectric laminated material having single layer.

However, in case of the method of manufacturing disclosed in the Patent Document 2, two substrates, which a plurality of thin-films are formed, need to be prepared, so there is a problem which a cost for materials increase. Further, a specific instrument and apparatus are needed when the substrates are adhered each other, so it needs another cost for that. Furthermore, a yield for the piezoelectric laminated material is likely to be decreased by performing adhering process, and two substrates are likely to peel off each other. Accordingly, in case of the method of manufacturing disclosed in the Patent Document 2, both improvement of the mass production capability and lowering of the manufacturing cost are difficult. Further, adhesive layer is likely to peel off each other and is likely to form a gap or crack in the piezoelectric laminated material.

On the other hand, the piezoelectric laminated material (thin-film piezoelectric material element) disclosed in the Patent Documents 3, 4 have a layer for relaxing a stress (stress relaxing layer).

However, in case of the piezoelectric laminated material disclosed in the Patent Document 3, the stress of the piezoelectric laminated material are only able to be decreased, originated in decrease of the stress in the electrodes. Further, in case of the piezoelectric laminated material disclosed in the Patent Document 4, the stress of the piezoelectric laminated material are only able to be decreased, originated in decrease of the stress being transmitted from one of the piezoelectric material to the other piezoelectric material. Therefore, curves (or bowing) of the piezoelectric laminated material are not able to be suppressed sufficiently in these conventional technologies. Further, the supplementary actuator used for hard disk drive does not need the crooked displacement, the crooked displacement are not able to be suppressed in these conventional technologies.

Hence, the present invention is made to solve the above problem, and its object is to make it possible to suppress curve (or bowing) and crooked displacement even the piezoelectric laminated material having a single layer, and to make it possible to manufacture a thin-film piezoelectric material element enhanced a adhesion strength of thin-films without loss of mass production capability and cost decreasing effect, in the thin-film piezoelectric material element, method of manufacturing the same, head gimbal assembly, hard disk drive, ink jet head, variable focus lens and sensor.

To solve the above problem, the present invention is a thin-film piezoelectric material element including: a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially; the piezoelectric material film has an upper surface of the upper electrode film side, and the upper surface is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected from a center surface of the concavity and convexity surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part, the upper electrode film is formed on the concavity and convexity surface, the thin-film piezoelectric material element including: a stress balancing film having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward a direction from the upper electrode film to the lower electrode film, the stress balancing film is formed on the upper electrode film so that a balance between the element stress and the internal stress is secured.

In case of the above-described thin-film piezoelectric material element, the stress balancing film has the internal stress capable of cancelling the element stress, and it is formed on the upper electrode film, thereby balance between the element stress and the internal stress is secured. Further, because the piezoelectric material film has the concavity and convexity surface, the upper electrode film is formed on the concavity and convexity surface, contact area about the piezoelectric material film and the upper electrode film is extended.

Further, it is preferable that the above-described thin-film piezoelectric material element further including: an upper adhesive film formed on the concavity and convexity surface, the upper adhesive film has a film thickness which at least half part from a lower surface of the concavity and convexity surface side to an upper surface of the stress balancing film side enter the concave part, an upper surface of the upper adhesive film of the upper electrode film side is a concavity and convexity surface according to the concavity and convexity surface of the piezoelectric material film, the upper electrode film is formed on the upper surface of the upper adhesive film.

In case of the thin-film piezoelectric material element, because the upper electrode film is formed via the upper adhesive film, adhesive strength of the piezoelectric material film and the upper electrode film is elevated.

Further, in case of the above-described thin-film piezoelectric material element, it is preferable that the upper electrode film has a film thickness which at least a part from a lower surface of the concavity and convexity surface side to an upper surface of the stress balancing film side enter the concave part, the upper surface of the stress balancing film side of the upper electrode film is a concavity and convexity surface according to the concavity and convexity surface of the piezoelectric material film, the stress balancing film is formed on the upper surface of the upper electrode film.

Because the upper surface of the upper electrode film is a concavity and convexity surface according to the piezoelectric material film, contact area with the stress balancing film is extended than a case of plane. Further, the stress balancing film formed on the upper electrode film has a stress including a stress originated in growth of crystal grains and a stress originated in the material.

Further, it is preferable that the stress balancing film is formed with the alloy material which includes iron as the main ingredient, the stress balancing film has a compressive stress which is generated in the neighborhood of grain boundary by contact of adjacent crystal grains, of plurality of crystal grains being formed on the upper electrode film at the time of depositing, caused by their growth, the stress balancing film has the internal stress including the compressive stress.

Further, it is preferable that the lower electrode film is formed as a (100) oriented film, having face-centered cubic structure, which includes the precious metals as the main ingredient, the upper electrode film includes a first metal layer formed on the concavity and convexity surface, a second metal layer formed on the first metal layer, the first metal layer is formed with the precious metals as the main ingredient, the second metal layer is formed with alloy material which has Young's modulus larger than the first metal layer and does not include the precious metals.

In case of the thin-film piezoelectric material element, the precious metals which constitute the lower electrode film and the precious metal which constitute the first metal layer are constituted with the same element.

Further, it is preferable that a thickness of the second metal layer is larger than a thickness of the first metal layer.

It is preferable that the upper electrode film has a film thickness which at least a part from a lower surface of the concavity and convexity surface side of the first metal layer to an upper surface of the stress balancing film side of the second metal layer enter the concave part, the upper surface of the stress balancing film side of the second metal layer is a concavity and convexity surface according to the concavity and convexity surface of the piezoelectric material film, the stress balancing film is formed on the upper surface of the second metal layer.

It is possible that the stress balancing film has a gap part, which is formed by mis-contact of adjacent crystal grains, between adjacent crystal grains.

Furthermore, it is preferable that the thin-film piezoelectric material element further including: a lower adhesive film formed on an upper surface of the lower electrode film of the piezoelectric material film side, the piezoelectric material film is formed on the lower adhesive film.

In case of the thin-film piezoelectric material element, it is preferable that film thicknesses of the stress balancing film and the upper electrode film are decreased in the order.

Further, the present invention provides a method of manufacturing a thin-film piezoelectric material element including a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially, the method including the following steps (1) to (4):

(1) a lower electrode film forming step of forming the lower electrode film on a substrate

(2) a piezoelectric material film forming step of forming the piezoelectric material film on the lower electrode film by sputtering, controlling deposition parameters, including deposition rate according to a deposition of the piezoelectric material, substrate temperature, gas pressure and gas composition, makes an upper surface, of the piezoelectric material film separated side from the substrate, a concavity and convexity surface includes a concave part and a convex part, the convex part is a curved surface convexly projected from a center surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part
(3) an upper electrode film forming step of forming the upper electrode film on the concavity and convexity surface
(4) a stress balancing film forming step of forming a stress balancing film, having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward the substrate, on the upper electrode film.

Further, the present invention provides a method of manufacturing a thin-film piezoelectric material element including a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially, the method including the following steps (5) to (8):

(5) a lower electrode film forming step of forming the lower electrode film on a substrate

(6) a piezoelectric material film forming step of forming the piezoelectric material film on the lower electrode film by sol-gel method, controlling deposition parameters, including number of rotations of spin-coating, drying temperature, prebake temperature, and oxygen pressure and temperature of a pressure anneal makes an upper surface, of the piezoelectric material film separated side from the substrate, a concavity and convexity surface includes a concave part and a convex part, the convex part is a curved surface convexly projected from a center surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part
(7) an upper electrode film forming step of forming the upper electrode film on the concavity and convexity surface
(8) a stress balancing film forming step of forming a stress balancing film, having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward the substrate, on the upper electrode film.

Further, it is preferable that the above-described method of manufacturing further including the following steps (9), (10), the upper adhesive film forming step, the upper electrode film forming step and the stress balancing film forming step are performed in a manner that film thicknesses of the stress balancing film, the upper electrode film and the upper adhesive film are decreased in the order, and at least half part of the upper adhesive film, from a lower surface of the concavity and convexity surface side to an upper surface of the stress balancing film side, enter the concave part.

(9) a lower adhesive film forming step of forming a lower adhesive film on an upper surface of the lower electrode film separated side from the substrate

(10) an upper adhesive film forming step of forming an upper adhesive film on the concavity and convexity surface

Further, the present invention provides a head gimbal assembly including a head slider having a thin-film magnetic head; a suspension for supporting the head slider; and a thin-film piezoelectric material element for displacing the head slider relatively to the suspension; the thin-film piezoelectric material element including: a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially; the piezoelectric material film has an upper surface of the upper electrode film side, and the upper surface is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected from a center surface of the concavity and convexity surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part, the upper electrode film is formed on the concavity and convexity surface, the thin-film piezoelectric material element including: a stress balancing film having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward a direction from the upper electrode film to the lower electrode film, the stress balancing film is formed on the upper electrode film so that a balance between the element stress and the internal stress is secured.

Further, the present invention provides a hard disk drive including a head gimbal assembly including a head slider having a thin-film magnetic head, a suspension for supporting the head slider, a thin-film piezoelectric material element for displacing the head slider relatively to the suspension; and a recording medium; the thin-film piezoelectric material element including: a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially; the piezoelectric material film has an upper surface of the upper electrode film side, and the upper surface is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected from a center surface of the concavity and convexity surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part, the upper electrode film is formed on the concavity and convexity surface, the thin-film piezoelectric material element including: a stress balancing film having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward a direction from the upper electrode film to the lower electrode film, the stress balancing film is formed on the upper electrode film so that a balance between the element stress and the internal stress is secured.

Further, the present invention provides an ink jet head including a head main body part including a plurality of nozzles and a plurality of ink chambers which communicate via each the nozzle, a thin-film piezoelectric material element being formed corresponding to the each ink chamber of the head main body part, and which is transformed so as to push out ink accommodated in each the ink chamber in accordance with recording signal; the thin-film piezoelectric material element including a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially; the piezoelectric material film has an upper surface of the upper electrode film side, and the upper surface is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected from a center surface of the concavity and convexity surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part, the upper electrode film is formed on the concavity and convexity surface, the thin-film piezoelectric material element including: a stress balancing film having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward a direction from the upper electrode film to the lower electrode film, the stress balancing film is formed on the upper electrode film so that a balance between the element stress and the internal stress is secured.

Further, the present invention provides a variable focus lens including a lens main body including a transparent substrate, a transparent resin accommodated the inside of the lens main body, a thin-film piezoelectric material element, for transforming the transparent resin, which is adhered to the lens main body; the thin-film piezoelectric material element including a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially; the piezoelectric material film has an upper surface of the upper electrode film side, and the upper surface is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected from a center surface of the concavity and convexity surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part, the upper electrode film is formed on the concavity and convexity surface, the thin-film piezoelectric material element comprising a stress balancing film having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward a direction from the upper electrode film to the lower electrode film, the stress balancing film is formed on the upper electrode film so that a balance between the element stress and the internal stress is secured.

Further, the present invention provides a sensor including a sensor main body including a concavity, a flexible member mounted to the sensor main body so as to cover the concavity, a thin-film piezoelectric material element which is adhered to the flexible member so as to transform the flexible member; the thin-film piezoelectric material element including a lower electrode film; a piezoelectric material film; and an upper electrode film; the lower electrode film, the piezoelectric material film and the upper electrode film are laminated sequentially; the piezoelectric material film has an upper surface of the upper electrode film side, and the upper surface is a concavity and convexity surface having a convex part and a concave part, the convex part is a curved surface convexly projected from a center surface of the concavity and convexity surface along a height direction, and the concave part is a curved surface concavely hollowed from the center surface and connected to the convex part, the upper electrode film is formed on the concavity and convexity surface, the thin-film piezoelectric material element including a stress balancing film having an internal stress capable of cancelling an element stress which the lower electrode film, the piezoelectric material film and the upper electrode film curve convexly toward a direction from the upper electrode film to the lower electrode film, the stress balancing film is formed on the upper electrode film so that a balance between the element stress and the internal stress is secured.

As explained above in detail, in the thin-film piezoelectric material element, method of manufacturing the same, head gimbal assembly, hard disk drive, ink jet head, variable focus lens and sensor, curve and crooked displacement are able to be suppressed even the piezoelectric laminated material having a single layer, and the thin-film piezoelectric material element enhanced a close adhesion of thin-film is able to be manufactured a without loss of mass production capability and cost decreasing effect.

The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following, embodiments of the present invention will be described with reference to the drawings. Note that the same components will be referred to with the same numerals or letters, while omitting their overlapping descriptions.

To begin with, a structure of the HGA according to the embodiment of the present invention will be explained with reference toFIG. 1toFIG. 5. Here,FIG. 1is a perspective view showing a whole of the HGA1, from front side, according to an embodiment of the present invention.FIG. 2is a perspective view showing a principal part of the HGA1from front side.FIG. 3is a perspective view showing a principal part of a suspension50constituting the HGA1from front side.FIG. 4is a perspective view showing a part of a flexure6, with enlargement, which a thin-film piezoelectric material element12bis fixed.FIG. 5is a sectional view taken along the line5-5inFIG. 4.

As illustrated inFIG. 1, the HGA1has the suspension50and a head slider60. The suspension50has a base plate2, a load beam3, the flexure6and a dumper not illustrated, and it has a structure which these parts are joined to be united one body by a weld and so on.

The base plate2is a part which is used to fix the suspension50to a drive arms209of a later-described hard disk drive201, and it is formed with a metal such as stainless steel or the like.

The load beam3is fixed on the base plate2. The load beam3has a shape in which the width gradually decreases as it is distanced more from the base plate2. The load beam3has a load bending part which generates a power for pressing the head slider60against the later-described hard disk202of the hard disk drive201.

Further, as illustrated inFIG. 1toFIG. 5, the flexure6has a flexure substrate4, a base insulating layer5, a connecting wiring11and thin-film piezoelectric material elements12a,12b, and further it has a later-described protective insulating layer25. The flexure6has a structure which the base insulating layer5is formed on the flexure substrate4, the connecting wiring11and thin-film piezoelectric material elements12a,12bare adhered on the base insulating layer5. Further, the protective insulating layer25is formed so as to cover the connecting wiring11and thin-film piezoelectric material elements12a,12b.

The flexure6has a piezoelectric elements attached structure which thin-film piezoelectric material elements12a,12bare fixed on the surface of the base insulating layer5in addition to the connecting wiring11to become a structure with piezoelectric element.

Further, the flexure6has a gimbal part10on the tip side (load beam3side). A tongue part19, which the head slider60is mounted, is secured on the gimbal part10, and a plurality of connecting pads20are formed near an edge side than the tongue part19. Connecting pads20are electrically connected to not-illustrated electrode pads of the head slider60.

This flexure6expands or shrinks thin-film piezoelectric material elements12a,12band expands or shrinks stainless part (referred to out trigger part) jut out outside of the tongue part19. That makes a position of the head slider60move very slightly around not-illustrated dimple, and a position of the head slider60is controlled minutely.

The flexure substrate4is a substrate for supporting a whole of the flexure6, and it is formed with stainless. Rear side of the flexure substrate4is fixed to the base plate2and the load beam3by weld. As illustrated inFIG. 1, the flexure substrate4has a center part4afixed to surfaces of the load beam3and the base plate2, and a wiring part4bextending to outside from the base plate2.

The base insulating layer5covers s surface of the flexure substrate4. The base insulating layer5is formed with for example polyimide, and it has a thickness of about 5 μm to 10 μm. Further, as illustrated in detail inFIG. 3, a part of the base insulating layer5, disposed on the load beam3, is divided two parts. One part of them is a first wiring part5a, the other part of them is second wiring part5b. The thin-film piezoelectric material element12aand thin-film piezoelectric material element12bare adhered on surfaces of each wiring part.

A plurality of connecting wirings11are formed on surfaces of each of the first wiring part5aand the second wiring part5b. Each connecting wiring11is formed with conductor such as copper or the like. One end parts of each connecting wiring11are connected to the thin-film piezoelectric material elements12a,12bor each connecting pad20.

The protective insulating layer25is formed with for example polyimide. The protective insulating layer25has a thickness of about 1 μm to 2 μm, for example.

Further, a not illustrated thin-film magnetic head, which re records and reproduces data, is formed on the head slider60. Furthermore, a plurality of not illustrated electrode pads are formed on the head slider60, and each electrode pad is connected to the connecting pads20.

Subsequently, the structure of thin-film piezoelectric material element will be explained with reference toFIG. 6toFIG. 8,FIG. 20in addition toFIG. 5. Here,FIG. 6is a sectional view showing a part of the thin-film piezoelectric material element12b, with enlargement, from an after-described piezoelectric material film13to a stress balancing film14.FIG. 7is a sectional view showing the piezoelectric material film13with enlargement.FIG. 8is a plan view schematically showing an upper surface of the piezoelectric material film13.FIG. 20is a sectional view showing a principal part ofFIG. 6with enlargement. Note that each film is described with emphasized concavity and convexity for convenience of illustration, inFIG. 6,FIG. 7,FIG. 20.

The thin-film piezoelectric material element12b(similar to thin-film piezoelectric material element12a), as illustrated in detail inFIG. 5, has a ground film15, a lower electrode film17, a lower adhesive film16a, the piezoelectric material film13, an upper adhesive film16b, an upper electrode film27and the stress balancing film14, and it has a laminated structure which each film is piled up in order. In the thin-film piezoelectric material element12b, the stress balancing film14is formed on the upper electrode film27so as to secure a balance between a later-described element stress F12and an internal stress F14. The thin-film piezoelectric material elements12b,12aare adhered to the surface of the base insulating layer5with not-illustrated epoxy resin.

Note that “upper” and “lower” in the present invention do not show necessarily upper side, lower side in a condition which the thin-film piezoelectric material element is adhered on the base insulating layer5. These words are terms for reasons of convenience so as to distinguish two electrode films and so on opposing each other with the piezoelectric material film13between. In the actual products, the upper electrode film27and the upper adhesive film16bare sometimes disposed lower side, and the lower electrode film17and the lower adhesive film16aare sometimes disposed upper side.

The piezoelectric material film13is formed to be a thin-film shape using a piezoelectric material such as lead zirconate titanate ((Pb (Zr,Ti) O3) which will also be referred to as “PZT” in the following) or the like. The piezoelectric material film13is formed by epitaxial growth and it has a thickness of about 2 μm to 5 μm. A piezoelectric ceramics (much of them are ferroelectric substance) such as barium titanate, lead titanate or the like, non-lead system piezoelectric ceramics not including titanium or lead are able to be used for the piezoelectric material film13instead of using PZT.

Further, in this embodiment, as illustrated inFIG. 6,FIG. 7, a surface of the upper electrode film27side of the piezoelectric material film13(referred to also as upper surface) is a concavity and convexity surface13A. The concavity and convexity surface13A has a plurality of bending convex parts13aand bending concave parts13b. In the concavity and convexity surface13A, each convex part13aand concave part13bare arranged one after the other along the concavity and convexity surface13A, and its sectional form is a wave form. Each convex part13aand concave part13bare curved surfaces which slant gently. In this embodiment, an outside part, convexly projected from a center surface13L along the height direction of the concavity and convexity surface13A, is the convex part13a, an inside part, concavely hollowed from the center surface13L and connected to the convex part13a, is the concave part13b.

Further, as illustrated inFIG. 8, each convex part13amay have a ridge part13c, and each concave part13bmay have a bottom of ravine part13d. The ridge part13cis a linear peak part which a plurality of tops are connected to be formed band shape. The bottom of ravine part13dis groove like part which a plurality of bottom parts are connected to be formed band shape along the convex part13a. Further, each ridge part13cand bottom of ravine part13dhave meandering structure respectively, and they extend along the length direction with crooking in left-right direction (direction intersecting with the thickness direction of the thin-film piezoelectric material element12b). Note that the upper surface of the piezoelectric material film13is not a surface which the convex part13aand the concave part13bhaving band shape, as illustrated inFIG. 8, are arranged one after the other, it may be a surface which a convex part and a concave part having different size and form are arranged one after the other, though they are not illustrated.

Furthermore, as illustrated inFIG. 20, a height difference between the convex part13aand concave part13b(referred to also as surface roughness) of the concavity and convexity surface13A is t13. And, a film thickness tl6b(about 35 nm) of the later-described upper adhesive film16bis almost equal to the surface roughness t13or slightly larger than the surface roughness t13. It is sufficient that at least half part from a lower surface to an upper surface of the upper adhesive film16benter the concave part13b, as illustrated inFIG. 6, almost the whole part enter the concave part13b. By this, as illustrated inFIG. 6,FIG. 8, the upper adhesive film16bhas a concavity and convexity structure according to the concavity and convexity surface13A of the piezoelectric material film13, the upper surface of the upper adhesive film16bbecomes concavity and convexity surface according to the concavity and convexity surface13A. In this case, the upper surface of the upper adhesive film16bhas a convex part and a concave part according to the concavity and convexity surface13A.

Further, a film thickness t27of the later-described upper electrode film27has a size, which at least a part from the lower surface (surface of the concavity and convexity surface13A side) to the upper surface (surface of the stress balancing film14side) of the upper electrode film27enters the concave part13b. Because the film thickness t27has such size, the upper electrode film27has also a concavity and convexity structure according to the concavity and convexity surface13A of the piezoelectric material film13, and its upper surface becomes concavity and convexity surface according to the concavity and convexity surface13A. Further, a film thickness t14(about 100 nm) of the later-described stress balancing film14is larger than the film thickness t27(t27<t14).

The ground film15is formed with zirconium oxide, yttrium oxide, magnesium oxide, rare earth elements oxide, nitride such as titanium nitride or the like. The ground film15as illustrated inFIG. 5has a first ground film15aand a second ground film15b, and it has two layers structure which the second ground film15bis formed on the first ground film15a. However, the ground film15does not need to have two layers structure.

The lower electrode film17is a thin-film (thickness about 100 nm) made of metal element which has Pt (it may include Au, Ag, Pd, Ir, Ru, Cu, in addition to Pt) as main ingredient, it is formed on the ground film15. A crystal structure of the lower electrode film17is a face-centered cubic structure. The lower adhesive film16ais a thin-film (thickness about 20 nm) made of conductive material formed by epitaxial growth such as SrRuO3(referred to also as SRO) or the like, and it is formed on an upper surface of the piezoelectric material film13side of the lower electrode film17. The piezoelectric material film13is formed on the lower adhesive film16a.

The upper adhesive film16bis a thin-film (thickness about 35 nm) made of amorphous conductive material such as SrRuO3or the like, and it is formed on the concavity and convexity surface13A of the piezoelectric material film13. As described above, the upper surface of the upper adhesive film16bbecomes a concavity and convexity surface according to the concavity and convexity surface13A.

The upper electrode film27is a polycrystal thin-film (thickness about 50 nm) with metal element which has Pt (it may include Au, Ag, Pd, Ir, Rh, Ni, Pb, Ru, Cu, in addition to Pt) as main ingredient, it is formed on the upper adhesive film16b. As described above, the upper surface of the upper electrode film27is a concavity and convexity surface according to the concavity and convexity surface13A. Further, a crystal structure of the upper electrode film27is a face-centered cubic structure.

The stress balancing film14is formed on the upper electrode film27. The stress balancing film14is a polycrystal thin-film (thickness about 100 nm) using alloy material. The stress balancing film14has an internal stress F14which is able to cancel (be able to offset) the later-described element stress F12.

The stress balancing film14is formed with alloy material which has iron (Fe) as main ingredient, for example. It is preferable that a crystal structure of the stress balancing film14is body-centered cubic structure. It is preferable that the stress balancing film14is formed with alloy material which includes Fe and at least any one of Co, Mo, Au, Pt, Al, Cu, Ag, Ta, Cr, Ti, Ni, Ir, Nb, Rb, Cs, Ba, V, W, Ru. Further, it is more preferable that the stress balancing film14is formed with alloy material which includes Fe and Co, Mo.

Here, the element stress F12is a stress which the lower electrode film17, the piezoelectric material film13and the upper electrode film27curve convexly along the direction from the upper electrode film27to the lower electrode film17(downward inFIG. 5), in thin-film piezoelectric material elements12b. The internal stress F14is a stress which the stress balancing film14has. The internal stress F14operates so as to spread the stress balancing film14toward outside, and make it curve convexly along upward.

Because the stress balancing film14having the compressive stress is formed on the upper electrode film27, the stress balancing film14pulls up the upper electrode film27upward direction, and the internal stress F14operates so as to cancel the element stress F12, thereby a balance of stress is secured. Note that the internal stress F14is a stress (resultant stress) which both a stress F14aoriginated in a material forming the stress balancing film14and a stress F14boriginated in a later-described growth of crystal grains of the stress balancing film14are composed, it is described in detail later.

Further, the stress balancing film14may have a plurality of gap parts14a,14b,14c,14d,14e, as illustrated inFIG. 11(A). Each gap part is a minute vacant space (or point defect) which is formed by mis-contact of adjacent crystal grains of crystal grains formed at deposition. In case these gap parts exist, the internal stress of the stress balancing film14become to be controlled easily, stress balance become to be performed easily.

Here,FIG. 15toFIG. 17are SEM (Scanning Electron Microscope) images showing a part of the thin-film piezoelectric material element12bmanufactured by the present inventor from the piezoelectric material film13to the upper electrode film27. As illustrated in these drawings, the upper surface of the piezoelectric material film13has the concavity and convexity structure.FIG. 18is a TEM (Transmission Electron Microscope) image showing a part of the stress balancing film14.FIG. 19is a TEM image showing a SAD (Selected Area Diffraction) pattern inFIG. 18.

Not illustrated wirings are formed on the upper electrode film27and the lower electrode film17. These wirings are connected to the connecting wirings11via electrode pads18a,18b.

The protective insulating layer25covers the surface of the base insulating layer5so as to cover all surfaces of the connecting wirings11, the thin-film piezoelectric material element12aand the thin-film piezoelectric material element12b. The protective insulating layer25is formed with polyimide for example, and it has a thickness of about 5 μm to 10 μm. It is preferable that the protective insulating layer25is manufactured together with not-illustrated cover layer of the flexure6. However, thin-film piezoelectric material elements12a,12bdo not need to be covered with the protective insulating layer25, when thin-film piezoelectric material elements12a,12bhave a protective insulating layer.

Further, the flexure6has a structure (piezoelectric element incorporated structure) which the thin-film piezoelectric material element12aand the thin-film piezoelectric material element12bare incorporated inside together with the connecting wirings11, because the protective insulating layer25is formed on the surface.

Note that the connecting wirings11, thin-film piezoelectric material element12aand thin-film piezoelectric material element12bare illustrated inFIG. 2toFIG. 4for convenience of illustration, however, they are covered with the protective insulating layer25, so they are not exposed on the surface of the flexure6.

Subsequently, a method of manufacturing the thin-film piezoelectric material element12bwill now be explained with reference toFIGS. 9(A) and9(B),FIGS. 10(A) and10(B),FIG. 12toFIG. 14. The thin-film piezoelectric material element12b(similar to the thin-film piezoelectric material element12a) is manufactured as following.

First, a substrate51made of Si (thickness of the substrate is about 100 μm to 3000 μm) is prepared, and epitaxial growth of a metal oxide thin-film such as ZrO2or the like is performed to formed the ground film15on the upper surface of the substrate51. The ground film15is able to be formed as single layer, and it is able to be formed as a pile of a plurality of layers, as illustrated inFIG. 12. It is possible that ZrO2film, rare earth elements oxide film made of rare earth elements including yttrium, and oxygen, mixture or laminated film of them are preferably able to be used as the ground film15.

Subsequently, a lower electrode film forming step is performed. In this step, epitaxial growth of metal element which has Pt as a main ingredient is performed on the ground film15by sputtering. This epitaxial growth makes the lower electrode film17. Next, a lower adhesive film forming step is performed. In this step, the lower adhesive film16ais formed with SRO for example, on upper surface of the lower electrode film17by sputtering.

After that, a piezoelectric material film forming step is performed. In this step, as illustrated inFIG. 13, epitaxial growth of piezoelectric material such as PZT or the like is performed on the lower adhesive film16aby sputtering. On that occasion, the piezoelectric material film13is formed so that the surface of the piezoelectric material has roughness and the upper surface becomes the above-described concavity and convexity surface13A, by controlling first deposition parameters.

Here, first deposition parameters are various parameters being adjusted when deposition of the piezoelectric material film13is performed by sputtering, and they have at least deposition rate, substrate temperature, gas pressure and gas composition. Numerical values of first deposition parameters, when the concavity and convexity surface13A is formed, are able to be a first piezoelectric material deposition condition.

The present inventor discovers that a PZT film is formed in accordance with composition of numerical values selected appropriately from the later-described first piezoelectric material deposition condition to appear desired roughness in the upper surface, thereby the concavity and convexity surface13A is formed, when epitaxial growth of the PZT film by sputtering is performed on the epitaxial film which the above-described ground film, lower electrode film and lower adhesive film are piled up on a silicon substrate, as a result of the various experiments.

First Piezoelectric Material Deposition Condition

deposition rate is about 0.1 to 3 μm/h, substrate temperature is about 350 to 750° C., gas pressure is about 0.01 to 10 Pa, gas composition is a mixture gas of argon and oxygen which oxygen partial pressure is set about 1 to 10%.

Therefore, in the piezoelectric material film forming step, the piezoelectric material film13having the concavity and convexity surface13A is able to be formed by controlling first deposition parameters so as to satisfy the first piezoelectric material deposition condition. In general, when substrate temperature is increased, the surface becomes rough to extend sizes of convex part and concave part easily, when substrate temperature is decreased, the sizes of convex part and concave part tend to small to be flatten the surface. The present inventor discovered the above-described first piezoelectric material deposition condition, as a result of the various experiments in view of the above.

Further, the piezoelectric material film forming step is also able to be performed as follows. In this case, epitaxial growth of piezoelectric material such as PZT or the like is performed on the lower adhesive film16aby sol-gel method. On that occasion, second deposition parameters are controlled to form the piezoelectric material film13having the concavity and convexity surface13A.

Second deposition parameters are various parameters which are adjusted when deposition of the piezoelectric material film13is performed by sol-gel method, and they have at least the number of rotations of spin-coating, drying temperature, prebake temperature and oxygen pressure and temperature of a pressure anneal. Numerical values of second deposition parameters, when the concavity and convexity surface13A is formed, are able to be a second piezoelectric material deposition condition.

The present inventor discovers that the PZT film is formed in accordance with composition of conditions selected appropriately from the later-described second piezoelectric material deposition condition to appear desired roughness in the upper surface, thereby the concavity and convexity surface13A is formed, when epitaxial growth of the PZT film by sol-gel method is performed on the epitaxial film which the above-described ground film, lower electrode film and lower adhesive film are piled up on a silicon substrate, as a result of the various experiments.

Second Piezoelectric Material Deposition Condition

number of rotations of spin-coating is about 3000 to 5000 rpm, drying temperature is about 200 to 300° C. (in oxygen), prebake temperature is about 400 to 500° C. (in oxygen), oxygen pressure and temperature of a pressure anneal is 3 to 10 atmospheric pressure and 600 to 800° C.

Subsequently, an upper adhesive film forming step is performed. In this step, the upper adhesive film16bis formed with SRO for example, on the concavity and convexity surface13A of the piezoelectric material film13by sputtering, as illustrated inFIG. 14.

As explained later, the upper electrode film27and the stress balancing film14are formed in the order on the upper adhesive film16bin later step. In this embodiment, the upper adhesive film forming step, the upper electrode film forming step and the stress balancing film forming step are performed as following so that the upper adhesive film16bhas the concavity and convexity structure similar to the concavity and convexity surface13A, and the upper electrode film27has also the concavity and convexity structure similar to the concavity and convexity surface13A. Namely, film thicknesses of the upper adhesive film16b, the upper electrode film27and the stress balancing film14are set several % (about 1 to 3%) of film thickness of the piezoelectric material film13, further film thicknesses of these films are decreased in order near to the piezoelectric material film13, namely in order of the stress balancing film14, the upper electrode film27and the upper adhesive film16b.

In this case, film thicknesses of the upper electrode film27and the upper adhesive film16bbecome extreme minute thickness which is extremely small than that of the piezoelectric material film13. Thus, because at least half part of the upper adhesive film16bfrom the lower surface to the upper surface may enter the concave part13b, the concavity and convexity structure of the concavity and convexity surface13A remains on the upper surface after the upper adhesive film16bis formed, so the upper surface does not become flat. Further, the concavity and convexity structure of the concavity and convexity surface13A remains on the upper surface after the upper electrode film27is formed.

Two layers of the upper adhesive film16band the upper electrode film27, which are formed before the stress balancing film14, are formed with small thickness than the stress balancing film14. Therefore, clear concavity and convexity structure appear on the surface (upper surface of the upper electrode film27) after these two layers are formed on the concavity and convexity surface13A. Accordingly, as explained later, the compressive stress originated in the growth of crystal grains is generated in the stress balancing film14.

Further, in the upper electrode film forming step, a growth of metal material having Pt as main ingredient is performed on the upper adhesive film16bby sputtering to form the upper electrode film27. The upper electrode film is not epitaxial growth film, it is a no-oriented polycrystal film or a preferentially oriented film with the (110) plane, or (111) plane.

As mentioned above, the lower adhesive film forming step and the upper adhesive film forming step are performed, thereby the piezoelectric material film13and the upper electrode film27are formed respectively on the lower electrode film17, the piezoelectric material film13via the lower adhesive film16a, the upper adhesive film16brespectively.

After that, the stress balancing film forming step is performed. In this step, the stress balancing film14is formed with alloy material (for example, alloy material including Fe, Co and Mo) having iron (Fe) as main ingredient, by sputtering. Thereby, the thin-film piezoelectric material element12bis obtained.

Note that the thin-film piezoelectric material element12bis manufactured with the substrate51, the substrate51is removed together with the ground film15by polishing or etching. Then a protective film made of polyimide and so on is formed, if necessary. And after a terminal is formed, the thin-film piezoelectric material elements12a,12bare adhered on a part which will become the tongue part19afterward using epoxy resin.

Here, a condition, which the upper electrode film27is formed on the piezoelectric material film13in the upper electrode film forming step, will be explained with reference toFIGS. 9(A) and9(B) andFIGS. 10(A) and10(B), as following. Note that an illustration of the upper adhesive film16bis omitted inFIGS. 9(A) and9(B) andFIGS. 10(A) and10(B).

To begin with, as illustrated inFIG. 9(A), a plurality of crystal grains27a,27b,27c,27d,27efor deposition of the upper electrode film27are formed on the concavity and convexity surface13A After that, these crystal grains27a,27b,27c,27d,27egrow. In this case, because the concavity and convexity surface13A has the concavity and convexity structure, directions of growth of each crystal grain27a,27b,27c,27d,27edo not become same direction. Therefore, as illustrated inFIG. 9(B), parts of the adjacent crystal grains begin contact caused by their growth. For example, as illustrated inFIG. 9(B), the crystal grain27b, crystal grain27c, and crystal grain27c, crystal grain27dcontact on part c1, part c2, respectively.

Further, each crystal grain27a,27b,27c,27d,27econtinues the growth, as illustrated inFIG. 10(A), repulsion force operates in the crystal grains (near grain boundary) which touch each other. The repulsion force trys to keep the crystal grains away. Then, the repulsion force operates so as to extend the upper electrode film27outward, as illustrated inFIG. 10(B). Therefore, this repulsion force appears as compressive stresses f1, f2in the whole of the upper electrode film27.

The upper electrode film27has such compressive stresses f1, f2. Compressive stresses f1, f2operate on the direction which curves the upper electrode film27upward.

Further, as explained above, because the upper electrode film27being formed in this way has also the concavity and convexity structure similar to the concavity and convexity surface13A, compressive stress F14bsimilar to compressive stresses f1, f2is generated in the stress balancing film14. This compressive stress F14bis the stress originated in the growth of crystal grains of the stress balancing film14.

(Operation and Effect of Thin-Film Piezoelectric Material Element)

As mentioned above, because the thin-film piezoelectric material element12bhas the piezoelectric material film13and the stress balancing film14, the thin-film piezoelectric material element12bhas the following operation and effect. Namely, the upper adhesive film16bis formed on the concavity and convexity surface13A of the piezoelectric material film13. But, film thickness of the upper adhesive film16bis minute thickness, the upper surface is a concavity and convexity surface similar to the concavity and convexity surface13A. Therefore, the upper electrode film27formed on the upper adhesive film16bhas internal stress being compressive stress.

Further, because the upper surface of the upper electrode film27is also the concavity and convexity surface similar to the concavity and convexity surface13A, the stress balancing film14has also the stress F14bbeing compressive stress. The stress balancing film14has internal stress including the stress F14b, originated in growth of crystal grains on a film having the concavity and convexity structure, and the stress F14aoriginated in the material, and it generates strong stress more than the thin-film which has only the stress F14aoriginated in the material. Because balance between the element stress F12and the internal stress F14is secured due to the formation of the stress balancing film14on the upper electrode film27, the thin-film piezoelectric material element12bhas highly improved stress balancing operation more than the conventional one. By this, balance of stress along to the thickness direction inside of the element is surely secured in the thin-film piezoelectric material element12b.

In a condition which the only element stress F12operates, the thin-film piezoelectric material element12bhas curved in a direction which the element stress F12operates. But, the internal stress F14operates in addition to the element stress F12, balance of the both stresses is surely secured in the thin-film piezoelectric material element12b. Therefore, the curve of the thin-film piezoelectric material element12bis suppressed sufficiently. As explained above, though the thin-film piezoelectric material element12bis a piezoelectric laminated material having a single layer, the curve of thin-film piezoelectric material element12bis suppressed sufficiently in spite of a condition which voltage is not applied, and crooked displacement is also able to be suppressed. Therefore, thin-film piezoelectric material element12bis suitable for the HGA.

Because crystal structure of the stress balancing film14is body-centered cubic structure, the stress balancing film14generates a large compressive stress in spite of small film thickness. Crystal structure of the upper electrode film27is face-centered cubic structure, the upper electrode film27generates compressive stress near the boundary to the stress balancing film14. Further, these crystal structure are different, crack and so on by external force is hardly to occur. Therefore, the thin-film piezoelectric material element12bhas high-degree reliability.

Further, because the thin-film piezoelectric material element12bhas the lower adhesive film16aand the upper adhesive film16b, adhesive strength of the lower electrode film17, the piezoelectric material film13and the upper electrode film27has been elevated. Furthermore, the concavity and convexity surface13A of the piezoelectric material film13has the concavity and convexity structure, the upper adhesive film16band the upper electrode film27have also concavity and convexity structure similar to this one. Then, because a contact area with another film is extended than the case each film is flat, adhesive strength between each film has been more elevated.

Further, because a plurality of laminated materials, piled up on the substrate in the manufacturing process, do not need adhesion in the thin-film piezoelectric material element12b, step for positioning of laminated material is not needed in the manufacturing process. Therefore, manufacturing process is able to be simplified, manufacturing cost is able to be reduced according to the above, in the thin-film piezoelectric material element12b. Accordingly, the thin-film piezoelectric material element12bis able to be manufactured without loss of mass production capability and cost decreasing effect.

Further, because adhesion about adhesive layers is not needed, adhesive layer is not likely to peel off each other and is not likely to form a gap or crack. Element reliability is improved according to the above.

And, in case the convex part13aand concave part13bof the concavity and convexity surface13A have the meandering structure, contact area between the upper adhesive film16band the concavity and convexity surface13A is enlarged. Thereby, adhesive strength of the piezoelectric material film13and the upper adhesive film16bhas been more improved, and reliability has been improved. Further, because the piezoelectric material film13is formed by epitaxial growth, the piezoelectric material film13is a film not having grain boundary, and it has good piezoelectric characteristic.

In case of the above-described piezoelectric material film13, as illustrated inFIG. 8, the convex part13aand concave part13bhave the meandering structure though, as illustrated inFIG. 21(A), it is possible that the convex part13aand concave part13bare formed by mostly straight line-shaped.

Further, as illustrated inFIG. 21(B), it is possible that the piezoelectric material film13has a plurality of meandering band shaped parts13v1,13v2,13v3,13v4which convex parts and concave parts are arranged one after the other along the longitudinal direction.

Modified Example 2

Subsequently, a thin-film piezoelectric material element112baccording to the modified example will be explained with reference toFIG. 22toFIGS. 24(A) and24(B).FIG. 22is a sectional view, similar withFIG. 5, showing a part of the flexure6which the thin-film piezoelectric material element112baccording to a modified example is fixed.FIG. 23is a sectional view showing a part of the thin-film piezoelectric material element112bwith enlargement from the piezoelectric material film13to the stress balancing film14.FIG. 24(A) is a sectional view, similar withFIG. 6, showing a principal part ofFIG. 23with enlargement, (B) is a sectional view showing a principal part of (A) with enlargement.

The thin-film piezoelectric material element112bis different in that it has an upper electrode film127in place of the upper electrode film27, as compared with the above-described thin-film piezoelectric material element12b. The upper electrode film127is different in that it has a first metal layer127aand a second metal layer127b, and it has two layers structure which the second metal layer127bis formed on the first metal layer127a, as compared with the upper electrode film27.

The first metal layer127ais formed with the precious metals (for example Pt) which is main ingredient. The second metal layer127bis formed with alloy material (for example, alloy material including Fe as a main ingredient) which has Young's modulus larger than the first metal layer127aand not including the precious metals. As illustrated inFIG. 24(B), the second metal layer127bis formed so that the thickness tb is larger than the thickness to of the first metal layer127a.

Further, the thin-film piezoelectric material element112bis formed so that the precious metal which constitutes the lower electrode film17is the same with the precious metal which constitutes the first metal layer127a. For example, both precious metals are able to be constituted with Pt as main ingredient. In the thin-film piezoelectric material element112b, the lower electrode film17is formed as a (100) oriented film, having face-centered cubic structure, made of the precious metals such as Pt or the like as main ingredient.

Further, as illustrated inFIG. 24(A), the upper electrode film127has a film thickness which a part, from the lower surface (surface of the concavity and convexity surface13A side) of the first metal layer127ato the upper surface (surface of the stress balancing film14side) of the second metal layer127b, is able to enter the concave part13b, equal to the upper electrode film27. Further, the upper surface of the second metal layer127bis a concavity and convexity surface corresponding to the concavity and convexity surface13A, the stress balancing film14is formed on the upper surface.

As mentioned above, in the thin-film piezoelectric material element112b, the upper electrode film127has the two layers structure including the first, second metal layers127a,127b, and Young's modulus of metal material constituting the second metal layer127bis larger than the Young's modulus of metal material constituting the first metal layer127a. Therefore, curve of the upper electrode film127is effectively suppressed. In case of two layers structure made of material which Young's modulus of upper side (the stress balancing film14side) is larger than the lower side as the upper electrode film127, internal stress which becomes compressive stress is enhanced more than the single layer as the upper electrode film27. Furthermore, because the thickness tb of the second metal layer127bis larger than the thickness to of the first metal layer127a, internal stress is more strengthen. Therefore, the upper electrode film127suppresses the curve of the thin-film piezoelectric material element112bpowerfully. Accordingly, the stress balancing operation of the thin-film piezoelectric material element112bis better than the thin-film piezoelectric material element12bby having the upper electrode film127.

Further, because upper surface of the upper electrode film127is a concavity and convexity surface similar to the upper electrode film27, the stress balancing film14has stress F14boriginated in growth of crystal grains in addition to the stress F14aoriginated in the material, thereby it generates strong stress. Accordingly, stress balance inside the element along to the thickness direction is surely secured in the thin-film piezoelectric material element112b, than the thin-film piezoelectric material element12b.

Crystal structure of the upper electrode film127is face-centered cubic structure, and it is different from the crystal structure of the stress balancing film14. Therefore, crack is not likely to occur from the stress balancing film14to the upper electrode film127when it receives outer force, thereby reliability of the thin-film piezoelectric material element112bis improved.

Further, because the lower electrode film17is formed as (100) oriented film having face-centered cubic structure made of precious metals such as Pt or the like as main ingredient, a compressive stress is generated effectively, on the upper surface of the piezoelectric material film13side.

Example

Present inventors form the piezoelectric material film13according to the-above described piezoelectric material deposition condition, after that, they form the stress balancing film14using alloy material including Fe, Co and Mo, thereby they form the thin-film piezoelectric material element12b. As a result, curve of the element is decreased largely, and crooked displacement along to the thickness direction is able to be suppressed. Further, they form the thin-film piezoelectric material element not having the stress balancing film14, they compared displacements (stroke sensitivities) per unit voltage along the longitudinal direction between both the thin-film piezoelectric material element, it is able to be confirmed that the stroke sensitivity of the former (the thin-film piezoelectric material element12bhaving the stress balancing film14) is improved about 40% than the stroke sensitivity of the latter.

Further, as a result of the X-ray Diffraction (XRD) measure, it is confirmed that lower electrode film made of Pt as main ingredient, lower adhesive film made of SRO and so on, and piezoelectric material film made of PZT and so on make epitaxial growth. The lower electrode film is a (100) oriented epitaxial film which (100) surface having face-centered cubic structure is oriented normal direction of film surface. Stress balancing film made of FeCoMo is a (110) oriented polycrystal film which (110) surface having body-centered cubic structure is oriented normal direction of film surface.

(Embodiments of Head Gimbal Assembly and Hard Disk Drive)

Next, embodiments of the head gimbal assembly and hard disk drive will now be explained with reference toFIG. 25.

FIG. 25is a perspective view illustrating a hard disk drive201equipped with the above-mentioned HGA1. The hard disk drive201includes a hard disk (magnetic recording medium)202rotating at a high speed and the HGA1. The hard disk drive201is an apparatus which actuates the HGA1, so as to record/reproduce data onto/from recording surfaces of the hard disk202. The hard disk202has a plurality of (4in the drawing) platters. Each platter has a recording surface opposing its corresponding the head slider60.

The hard disk drive201positions the head slider60on a track by an assembly carriage device203. A thin-film magnetic head, not illustrated, is formed on this head slider60. Further, the hard disk drive201has a plurality of drive arms209. The drive arms209pivot about a pivot bearing shaft206by means of a voice coil motor (VCM)205, and are stacked in a direction along the pivot bearing shaft206. Further, the HGA1is attached to the tip of each drive arm209.

Further, the hard disk drive201has a control circuit204controlling recording/reproducing.

In the hard disk drive201, when the HGA210is rotated, the head slider60moves in a radial direction of the hard disk202, i.e., a direction traversing track lines.

In case such HGA1and hard disk drive201are formed with the above-described thin-film piezoelectric material elements12a,12b, because curves of the thin-film piezoelectric material elements12a,12bare suppressed, mounting of the thin-film piezoelectric material elements12a,12b(fixing to the base insulating layer5) is easily performed. Further, because damage of the thin-film piezoelectric material elements12a,12bat the timing of mounting is suppressed, yield of manufacturing the HGA1and the hard disk drive201has been improved.

Further, because thin-film piezoelectric material elements12a,12bhave high stroke sensitivity in spite of a single layer, they are able to generate displacement along the longitudinal direction efficiently in comparison with a case of using the conventional thin-film piezoelectric material element, and position of the thin-film magnetic head is able to be adjusted effectively. Furthermore, thin-film piezoelectric material elements12a,12bhave high stress balancing operation to an extent of being able to suppress the crooked displacement surely, in spite of a single layer. Further, because adhesive strength of thin-films is high, the HGA1and the hard disk drive201are able to be manufactured without loss of mass production capability and cost decreasing effect.

(Embodiments of Ink Jet Head)

Next, embodiments of the Ink Jet Head will now be explained with reference toFIG. 26.

FIG. 26is a sectional view showing a summary constitution of the ink jet head301. The ink jet head301is manufactured with thin-film piezoelectric material elements312a,312b,312c. The ink jet head301has a head main body part302and thin-film piezoelectric material elements312a,312b,312c.

The head main body part302has an ink passage structure body303and a vibration member305.

The ink passage structure body303has a substrate303A which a plurality of nozzles303a,303b,303cand ink passages304a,304b,304c(3 pieces inFIG. 26) and it has a structure which a plurality of ink chambers306a,306b,306care formed so as to correspond to the each nozzle303a,303b,303cand the each ink passage304a,304b,304c. Each ink chamber306a,306b,306cis partitioned by a side wall part307, and each of them communicates via nozzles303a,303b,303cthrough ink passages304a,304b,304c. Ink, not illustrated, is accommodated in each ink chamber306a,306b,306c. The ink passage structure body303is able to be manufactured with a various kinds of material such as resin, metal, silicon (Si) substrate, glass substrate, ceramics or the like.

The vibration member305is adhered to the ink passage structure body303so as to cover a plurality of ink chambers306a,306b,306c. The vibration member305is formed with silicon oxide (SiO) for example, and it has a thickness of about 3.5 μm. Then, thin-film piezoelectric material elements312a,312b,312care adhered to the outside of the vibration member305so as to correspond to the each ink chambers306a,306b,306c. Thin-film piezoelectric material elements312a,312b,312care adhered to the vibration member305with adhesive313.

The structure of each thin-film piezoelectric material element312a,312b,312cis the same as the structure of the above-described thin-film piezoelectric material element12b. Further, each thin-film piezoelectric material element312a,312b,312chas not-illustrated electrode terminals. Not-illustrated wiring is connected to each electrode terminal.

The head main body part302and the ink jet head301are able to be manufactured as follows. To begin with, nozzles303a,303b,303cand ink passages304a,304b,304care formed on the substrate303A by machining. Next, the side wall part307, which ink chambers306a,306b,306care formed by machining or etching, is adhered to the substrate303A. Or the side wall part307is formed on the substrate303A by plating. Then, the ink passage structure body303is manufactured. After that, the vibration member305is adhered to the ink passage structure body303to manufacture the head main body part302.

Then, the substrate51is removed together with the above-described ground film15by polishing or etching, and thin-film piezoelectric material elements312a,312b,312care manufactured, further they are adhered to the vibration member305with adhesive313such as epoxy resin or the like. Then the ink jet head301is manufactured.

When electric power is supplied to thin-film piezoelectric material elements312a,312b,312cvia the wiring and electrode terminal from a not-illustrated power source concerning the ink jet head301manufactured as the above, as illustrated inFIG. 26, for example, transformation of the thin-film piezoelectric material elements312bmakes a curved part305ain the vibration member305. Then, the ink accommodated in each ink chamber306a,306b,306cis pushed out, and the ink is ejected via ink passages304a,304b,304cand nozzles303a,303b,303c.

Because curves of the thin-film piezoelectric material elements312a,312b,312care suppressed equal to the above-described thin-film piezoelectric material elements12b, adhering of thin-film piezoelectric material elements312a,312b,312cto the vibration member305is easily performed. Further, because thin-film piezoelectric material element, manufactured on the substrate another from the head main body part302, is adhered to the vibration member305, thin-film piezoelectric material elements312a,312b,312care arranged efficiently. Furthermore, because limitation for material of the substrate303A is reduced, manufacturing cost of the ink jet head301is able to be reduced than the conventional one.

Further, in the ink jet head301, limitation for material of the head main body part302is reduced than a case which a lower electrode film, a piezoelectric material film and an upper electrode film are formed on a silicon substrate and ink passages and nozzles are formed on the silicon substrate by reactive ion etching or the like, so various kinds of material are able to be used for the head main body part302. Therefore, the method with low cost than a processing such as reactive ion etching or the like is able to be used when the head main body part302is manufactured, the ink jet head301is manufactured easily. Further, nozzles and ink passages are formed respectively with another substrates, and nozzles and ink passages are joined together, after that, the thin-film piezoelectric material element is adhered to them, thereby the ink jet head is able to be manufactured, though they are not illustrated. In this case, nozzles are able to be formed by machining and ink passages are able to be formed by plating.

(Embodiments of Variable Focus Lens)

Next, embodiments of variable focus lens will now be explained with reference toFIG. 27,FIG. 28.

FIG. 27is a plan view showing a summary constitution of variable focus lens401according to the embodiment.FIG. 28is a sectional view taken along the line28-28inFIG. 27. The variable focus lens401has a lens main body part410and two thin-film piezoelectric material elements412,412.

The lens main body part410has a transparent substrate402, a metal formed casing403, a transparent elastic member404, a transparent gel like resin405and a metal ring member406.

The transparent substrate402is made of a transparent member such as glass or the like, and it is formed by a rectangular shape. The metal formed casing403is a pipe-shaped body, with a rectangular shape in a plan view, having a size corresponding to the transparent substrate402, and a pipe-shaped gap part403ais formed inside the metal formed casing403. The metal formed casing403is formed with stainless for example. The transparent elastic member404is formed with a member, having a transparency and elasticity and being transformed easily, such as a transparent polymer or the like, and it fits to the pipe-shaped gap part403aof the metal formed casing403without gap. Further, inside of the transparent elastic member404is a cylindrical gap part404a. The transparent gel like resin405is made of silicone resin or the like, and it is accommodated in the cylindrical gap part404aof the transparent elastic member404. The transparent gel like resin405presents a cylindrical shape by fitting to the inside wall of the cylindrical gap part404awithout gap. The metal ring member406is a circular loop like member having a moderate thickness, and it is placed on the surface of the transparent gel like resin405, in the cylindrical gap part404a.

And, thin-film piezoelectric material elements412a,412bare bridged over the metal ring member406and the metal formed casing403across the transparent elastic member404, and they are adhered to them with not-illustrated adhesive. Each thin-film piezoelectric material element412,412is arranged on the straight line which passes through a center of the transparent gel like resin405, so as to oppose each other intervening the center of the transparent gel like resin405.

The structure of each thin-film piezoelectric material element412,412is the same as the structure of the above-described thin-film piezoelectric material elements12b. Further, each thin-film piezoelectric material element412,412has not-illustrated electrode terminal. Not-illustrated wiring is connected to each electrode terminal.

The variable focus lens401having the above-described structure is manufactured as follows. To begin with, the substrate51is removed together with the above-described ground film15by polishing or etching, and thin-film piezoelectric material elements412,412are manufactured. Further thin-film piezoelectric material elements412,412are adhered to the lens main body part410with not-illustrated adhesive. Then, the variable focus lens401is manufactured.

When electric power is supplied to each thin-film piezoelectric material element412,412via the wiring, concerning the above-described variable focus lens401manufactured as the above, each thin-film piezoelectric material element412,412is transformed. The metal ring member406is pushed in accordance with the transformation, and thereby the transparent gel like resin405is transformed. In this way, the focus length of the variable focus lens401is able to be changed. Because curve of the thin-film piezoelectric material element412is suppressed equal to the above-described thin-film piezoelectric material elements12b, adhering of thin-film piezoelectric material element412to the lens main body part410is easily performed.

(Modified Example of Variable Focus Lens)

Next, modified example of variable focus lens will now be explained with reference toFIG. 29.FIG. 29is a sectional view showing the summary constitution of the variable focus lens451according to the modified example. The variable focus lens451has the lens main body part452and thin-film piezoelectric material elements412,412.

The lens main body part452has the transparent glass substrate453,453, sealing resin member454and the transparent gel like resin455.

The transparent glass substrates453,453has a board like form having a thin thickness, and it has a moderate elasticity capable of being curved moderately. The transparent glass substrates453,453are arranged so as to confront each other at predetermined interval. Sealing resin member454is adhered to the all surrounding of gap space between transparent glass substrates453,453. The sealed up space456is formed by the above-described transparent glass substrates453,453and the sealing resin member454, and the transparent gel like resin455, equal to the transparent gel like resin405, is accommodated in the sealed up space456.

Then, thin-film piezoelectric material elements412,412are adhered to the outside of the one of the transparent glass substrate453,453using not-illustrated adhesive. These thin-film piezoelectric material elements412have not-illustrated electrode terminals equal to the above-described variable focus lens401. Not-illustrated wiring is connected to the electrode terminals. When electric power is supplied to thin-film piezoelectric material elements412,412via the wiring, thin-film piezoelectric material elements412,412are transformed. The transformation makes a transformation (or a bending) of the transparent glass substrate453, and thereby the transparent gel like resin455is transformed. In this way, focus length of the variable focus lens451is able to be changed. Because curves of the thin-film piezoelectric material elements412,412in the variable focus lens451are also suppressed equal to the above-described thin-film piezoelectric material element12b, adhering of thin-film piezoelectric material elements412,412to the lens main body part452is easily performed.

(Embodiments of Pulse Wave Sensor)

Next, embodiments of pulse wave sensor will now be explained with reference toFIG. 30.FIG. 30is a sectional view showing a summary constitution of the pulse wave sensor501according to the embodiment. The pulse wave sensor501has a sensor main body part502and a thin-film piezoelectric material element512.

The sensor main body part502has a metal formed casing504, a sealing member505, a vibration plate503made of flexible member, metal pad507, a wiring member509and a lead510.

The metal formed casing504is formed with a metal such as aluminium, stainless or the like. The metal formed casing504is a cylindrical member with bottom, which a concavity part501ais formed at a center, and a wall part501bis formed so as to surround the concavity part501a. The sealing member505is made of member having elasticity such as silicone resin or the like, and it is adhered to part between a wall part501bof the metal formed casing504and the vibration plate503. The vibration plate503is formed to be a circular plate shape, having of 10 mm diameter, and 0.1 mm thickness. The vibration plate503is formed with a metal such as stainless or the like so that it is able to be transformed.

The metal pad507is made of Au, Cr, Cu or the like, and it is adhered to the inside (the concavity part501aside) of vibration plate503, using adhesive506bsuch as epoxy resin or the like. The metal pad507is connected to the thin-film piezoelectric material element512by a wiring member509made of Au or the like. Further, the metal pad507is also connected to the lead510by solder508. The lead510is connected to the not-illustrated power source.

Then, the thin-film piezoelectric material element512is connected to the inside (the concavity part501aside) of the vibration plate503, using adhesive506asuch as epoxy resin or the like. The structure of the thin-film piezoelectric material element512is the same as the structure of the above-described thin-film piezoelectric material elements12b. Further, the wiring member509is connected to the thin-film piezoelectric material element512.

The above-described pulse wave sensor501is used as follows. The vibration plate503is brought into contact with the human body such as not-illustrated arm or the like. Then, the pulsation of the human body is transmitted to the vibration plate503, and the vibration plate503is transformed. When the vibration plate503is transformed, the thin-film piezoelectric material element512is transformed in accordance with the transformation, and feeble electric signal (pulse wave signal), in accordance with the transformation, is outputted from the thin-film piezoelectric material element512. The electric signal is outputted in the outside via the wiring member509, the metal pad507and the lead510. When the electric signal is amplified by the not-described amplifier, the wave form of the pulse wave signal is able to be observed. In this way, the pulse wave signal is able to be detected by the pulse wave sensor501. Because curve of the thin-film piezoelectric material element512is suppressed equal to the above-described thin-film piezoelectric material element12b, adhering of thin-film piezoelectric material element512to the vibration plate503is easily performed.

Note that though the pulse wave sensor is explained as the sensor by way of example in the above-described embodiment, the present invention is also applicable to various kinds of sensors such as a pressure sensor, vibration sensor, accelerometer and load sensor or the like.

Curve and crooked displacement become to be fully suppressed in spite of the piezoelectric laminated material having a single layer by applying the present invention, further, the thin-film piezoelectric material element, enhanced a adhesion strength of thin-film, is able to be manufactured without loss of mass production capability and cost decreasing effect. The present invention is able to be utilized for the thin-film piezoelectric material element, method of manufacturing the same, head gimbal assembly, hard disk drive, ink jet head, variable focus lens and sensor having the thin-film piezoelectric material element.

This invention is not limited to the foregoing embodiments but various changes and modifications of its components may be made without departing from the scope of the present invention. Besides, it is clear that various embodiments and modified examples of the present invention can be carried out on the basis of the foregoing explanation. Therefore, the present invention can be carried out in modes other than the above-mentioned best modes within the scope equivalent to the following claims.