JP2003229611A - Thin film piezoelectric element, production method therefor and thin film piezoelectric element for hard disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to use a substrate except for a monocrystal oxide magnesium substrate. <P>SOLUTION: A laminate laminating a first electrode metal film 310A, a first thin film piezoelectric body 210A and a second electrode metal film 330A in such order; and a laminate laminating a third electrode metal film 320A, a second thin film piezoelectric body 220A, and a fourth metal film 340A in such order; are adhered on the second electrode metal film 330A and the fourth electrode metal film 340A. At least one part thereof is coated with a resin, a first terminal is provided for applying a driving voltage to the first electrode metal film 310A and the third electrode metal film 320A, and a second terminal is provided for applying a ground voltage to the second electrode metal film 330A and the fourth electrode metal film 340A. In such a thin film piezoelectric element, a silicon substrate forming an oxide magnesium film is used in place of the monocrystal oxide magnesium substrate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film piezoelectric element and a method for manufacturing the same, and more particularly to a head suitable for increasing data recording density in a magnetic disk device or the like used as an information recording device of a computer. The present invention relates to an actuator preferably used for a support mechanism.

[0002]

2. Description of the Related Art In recent years, the recording density of a magnetic disk provided in a magnetic disk device has been increasing at a high rate of tens of percent per year. A magnetic head used for recording / reproducing data on / from a magnetic disk is usually mounted on a slider, and the slider on which the magnetic head is mounted is supported by a head supporting mechanism provided in the magnetic disk device. . The head support mechanism has a head actuator arm to which a slider is attached, and this head actuator arm has a voice coil motor (VC).
It is designed to be rotated by M). Then, by controlling the voice coil motor, the head mounted on the slider is positioned at an arbitrary position on the magnetic disk.

In order to record data on the magnetic disk at a higher density, it is necessary to position the magnetic head on the magnetic disk at a higher density. However, such a configuration in which the head actuator arm is rotated by the VCM to position the magnetic head has a problem that the magnetic head cannot be positioned with higher accuracy.

Therefore, the present inventors have filed Japanese Patent Application No. 2000-322.
At 020, a new method was proposed. In this method, the head is roughly positioned by rotating the head actuator arm with the VCM as in the conventional case, but accurate positioning is performed by the thin film piezoelectric element attached to the magnetic head. With such a structure, high-accuracy and high-speed positioning is possible.

A plan view of a conventional thin film piezoelectric element is shown in FIG. This thin film piezoelectric element is a pair of elements 10A and 10B having the same structure, which are paired so as to be bilaterally symmetrical to each other, and its cross section (cross section along line XX ').
Is shown in FIG.

Each element 10A, 10 of the thin film piezoelectric element 10
Each of B has a two-layer structure, and a first electrode metal film 31A and a third electrode film 33A are formed on the upper side and the lower side of the first thin film piezoelectric body 21A located above. Further, the second thin film piezoelectric element 22A located at the lower portion is arranged below the first thin film piezoelectric element 21A, and the second electrode metal film 32A and the fourth electrode metal film are similarly formed on both surfaces thereof. 34A is provided. The third electrode metal film 33A and the fourth electrode metal film 34A are electrically short-circuited. At least a part of the thin film piezoelectric element 10 is made of a flexible resin 15
Is covered with.

An outline of the method of manufacturing this thin film piezoelectric element is shown in FIG. As shown in FIGS. 3A and 3B, the single crystal magnesium oxide substrate 41 having a (200) plane as a film formation surface, whose lattice constant of the film formation surface is similar to that of a thin film piezoelectric material.
A first (third) electrode metal film on (42) {for example, (2
00A plane preferentially oriented platinum} 31A (32A), first
A (second) piezoelectric thin film {for example, lead zirconate titanate (PZT)} 21A (22A) and a second (fourth) electrode metal film (for example, Ta / Au film) 33A (34A) are formed in this order by sputtering. Be filmed. As a result, the thin film piezoelectric material 21A
(22A) is the first (third) electrode metal film 31A (32A)
Oriented growth occurs on A), and the polarization direction is almost perpendicular to the film surface. Next, the second electrode metal film 33A and the fourth electrode metal film 34A are bonded with the adhesive 14 (FIG. 3).
(C)}. Next, the first single crystal magnesium oxide substrate 41
Are removed by etching {FIG. 3 (d)}. Next, it is formed by dry etching or the like so as to have a predetermined thin film piezoelectric element shape {FIG. 3 (e)}. As a result, the elements 10A and 10B forming the thin film piezoelectric element 10 are substantially formed.

Next, the second single crystal magnesium oxide substrate 4
The surface on which the thin film piezoelectric element is formed is covered with the coating resin 15 to prevent the thin film piezoelectric element from being damaged or deteriorated (FIG. 3 (f)), and the second remaining single crystal oxide is left. By removing the magnesium substrate 42 by etching {FIG. 3 (g)}, the element 10A and the element 10B that form the thin film piezoelectric element 10 are obtained.

The step of forming a first terminal for applying a drive voltage to the first electrode metal film 31A and the third electrode metal film 32A, and the second electrode metal film 33A and the fourth electrode metal film 34A. Illustration of the step of forming the ground voltage is omitted.

[0010]

However, in this manufacturing method, the single crystal magnesium oxide substrate had a big problem.

Single crystal magnesium oxide has a melting point of 2850.
Since the temperature is as high as ℃, it cannot be manufactured by the pulling method like a silicon single crystal. Therefore, after arc melting the raw material polycrystalline magnesium oxide in a large furnace body,
A single crystal is obtained by natural cooling. According to this method, the size of a single crystal that is usually obtained is about several cm square, and the yield thereof is only about 1/1000 with respect to the raw material polycrystalline magnesium oxide. Therefore, the single crystal magnesium oxide substrate is expensive (the price per unit area is 50 to 100 times that of the silicon substrate single crystal). Moreover, since the size of the single crystal lump obtained as described above is several cm square, the obtained substrate must be a small size of about 2 to 3 cm square, and the increase in the element manufacturing cost due to it cannot be ignored. .

Not only the thin-film piezoelectric material but also semiconductors, thin-film heads, and other devices that use a large number of thin-film processes, it is generally advantageous in terms of manufacturing cost that the substrate size is large. Therefore, in the field of semiconductor manufacturing, the size of the substrate is being increased, and the silicon substrate, which was initially 50 to 76 mm, is about to reach the 300 mm diameter age in the 21st century.

Also in the thin film piezoelectric element, in order to reduce the substrate cost and the manufacturing cost, it is desirable to use a substrate that is cheaper and has a larger diameter than the single crystal magnesium substrate.

An object of the present invention is to produce a thin film piezoelectric element inexpensively and efficiently by using another substrate instead of the single crystal magnesium oxide substrate.

[0015]

A thin film piezoelectric element of the present invention comprises a laminated body in which a first electrode metal film, a first thin film piezoelectric body, and a second electrode metal film are laminated in this order, and a third electrode metal. A film, a second thin film piezoelectric body, and a laminated body in which a fourth metal film is laminated in this order are adhered to each other by the second electrode metal film and the fourth electrode metal film, and at least a part thereof is covered with a resin. Is the first
A second terminal for applying a driving voltage to the electrode metal film and the third electrode metal film, and a second terminal for applying a ground voltage to the second electrode metal film and the fourth electrode metal film A thin film piezoelectric element comprising: a surface of at least one of the first electrode metal film and the third electrode metal film, on which the thin film piezoelectric body is not formed, which is preferentially oriented to the (200) plane. The magnesium film is formed.

According to the method of manufacturing a thin film piezoelectric element of the present invention, a first substrate is prepared by laminating a first electrode metal film, a first thin film piezoelectric body and a second electrode metal in this order on a first substrate. A step of manufacturing a second substrate in which a third electrode metal film, a second thin film piezoelectric body, and a fourth electrode metal are laminated in this order on a second substrate; the first substrate and the first substrate; After bonding the second substrate to the second electrode metal film surface and the fourth metal electrode film surface, the first substrate is removed by etching to remove the first electrode metal film and the first thin film piezoelectric film. The body, the second electrode metal film, the fourth electrode metal film, the second thin film piezoelectric body, and the third electrode metal film are processed into a predetermined shape, and at the same time, the first electrode metal film and the third electrode. A first terminal for applying a driving voltage is formed on the metal film, and the second electrode metal and the fourth electrode metal film are formed. After a step of forming a second terminal for applying a ground voltage to the substrate and a coating process with a resin for preventing an adverse effect from the external environment, the second substrate is removed to form a thin film piezoelectric element. Have a process of making,
As the first substrate and the second substrate, a single crystal silicon substrate having a surface on which a magnesium oxide film preferentially oriented in the (200) plane is formed is used.

[0017]

According to the thin-film piezoelectric material element of the present invention, at least one of the first electrode metal film and the third electrode metal film is provided with (20
Since the preferentially oriented magnesium oxide film is formed on the (0) plane, a substrate other than the single crystal magnesium oxide substrate can be adopted. Therefore, it is possible to reduce the cost of the thin film piezoelectric element by using a substrate (for example, a silicon substrate) that is cheaper than the single crystal magnesium oxide substrate and has a large diameter.

Here, the thickness of the magnesium oxide film is preferably 10 nm or more and 500 nm or less. The reason is ECR sputtering method, RF bipolar sputtering method, R
F magnetron sputtering method, plasma CVD method, ECR
-As a result of studying film formation by the CVD method or the like, the film thickness is 10 nm
In the following, it is difficult to obtain a dense magnesium oxide film having excellent crystallinity, and when the film thickness is 500 nm or more, the roughness of the film surface becomes too large, and the Pt electrode film formed thereon has only the (100) plane. This is because the (111) plane is also strongly precipitated.

It is preferable to use Pt films as the first electrode metal film and the third electrode metal film, and it is possible to form a piezoelectric thin film having predetermined characteristics even if a silicon substrate is used. That is, it is known that Pt has a property of transmitting the characteristics of the underlying layer to the upper layer. In the thin film piezoelectric element of the present invention, it is necessary to epitaxially grow the piezoelectric film on the magnesium oxide film preferentially oriented on the (200) plane. Because there is
It is preferable to employ a Pt film as the electrode metal film and the third electrode metal film.

As the second electrode metal film and the fourth electrode metal film, a laminated film composed of at least two kinds of metal films selected from Pt, Ta, Au, Rh, Cu, Ti and Cr is adopted. Is preferred. The reason is that the second electrode film and the fourth electrode film formed on the upper layer of the piezoelectric film do not need to be Pt, but since they are electrode films, they have low electrical resistance and are chemically stable. Therefore, Au, Cu, Rh, and Pt are suitable as the material. However, since the adhesiveness with the piezoelectric film is not always sufficient, Ta, Ti, This is because it is preferable to interpose an extremely thin film such as Cr.

As the first thin film piezoelectric body and the second thin film piezoelectric body, it is preferable to adopt a lead type piezoelectric material such as lead zirconate titanate, lead strontium titanate, or lead titanate. A silicon substrate / platinum film / magnesium oxide thin film can be used as an alternative to the single crystal magnesium oxide substrate.

According to the method of manufacturing a thin film piezoelectric element of the present invention, a single crystal having a (200) plane preferentially oriented magnesium oxide film formed on the surfaces of the first substrate and the second substrate. Since the silicon substrate is used, the thin film piezoelectric element can be manufactured at a low cost by adopting a silicon substrate which is cheaper than the single crystal magnesium oxide substrate and can have a large diameter.

Further description will be made.

In order to obtain a high-performance thin film piezoelectric element, it is necessary that the piezoelectric thin film is polarized in a direction perpendicular to or close to the film surface. For that purpose, it is desirable that the piezoelectric thin film has a perovskite structure and that the film surface is (001) -oriented. In order to obtain a piezoelectric thin film having such a crystal structure, a piezoelectric thin film is generally epitaxially grown using a substrate whose film-forming surface has the same lattice constant and crystal structure as the piezoelectric thin film.

Lead zirconate titanate (PZT) is used for the piezoelectric body.
Consider the case of using. Lead zirconate titanate (10
The lattice constant of the (0) plane is around 0.404 nm, the lattice constant of the (200) plane is around 0.202 nm, the lattice constant of the (200) plane of the MgO single crystal substrate is around 0.211 nm, and the lattice constant of the (200) plane of Pt is The lattice constant is around 0.196 nm.
Therefore, according to the conventional method, a Pt (200) plane as an electrode metal film is epitaxially grown on the MgO single crystal (200) plane, and a lead zirconate titanate film is further formed on the Pt (200) plane to epitaxially grow on the (100) plane. ing.

On the other hand, the present inventor adopts, instead of the single crystal MgO substrate, a Si single crystal substrate on which a MgO film preferentially oriented in the (200) plane is formed. The present inventors have completed the present invention by finding that the effect of the above can be obtained, and the cost of the thin film piezoelectric element can be reduced.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a thin film piezoelectric element and a method of manufacturing the same according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 5 is a plan view showing an example of the thin film piezoelectric element of the present invention, and a pair of elements 10 having exactly the same structure.
The thin film piezoelectric element 100 is configured by pairing 0A and 100B so as to be bilaterally symmetrical to each other.

Next, the manufacturing method will be described.

As shown in FIGS. 4A and 4B, a magnesium oxide film 510A (520A) whose film surface is preferentially oriented to the (200) surface is formed on the single crystal silicon substrate 430 (440) by the ECR sputtering method. ) Is deposited to a thickness of 200 nm.
A Pt film 310A (32) which is a first (third) electrode metal film with a film thickness of 200 nm preferentially oriented to the (200) plane is formed on the Pt film 310A
0A), a first (second) piezoelectric thin film {lead zirconate titanate (PZT) having a thin film of 2 μm} 210A (220A),
Ta (film thickness 30n as a second (fourth) electrode metal film
m) / Au (thickness 300 nm) film 330A (340A)
Are deposited in this order. Here, the Ta film plays a role of enhancing the adhesiveness between the Au film and the PZT film. With this configuration, the Pt film 310A that is the first (third) electrode metal film
(320A) is a magnesium oxide film 510A (520A).
A) is epitaxially grown with respect to (A) to have a (200) plane orientation, and a piezoelectric thin film 210A further formed thereon.
(220A) is also the first (third) electrode metal film 310A (3
20A) is epitaxially grown on the (20A) plane and is oriented in the (001) plane, and its polarization direction is substantially perpendicular to the film surface.
Next, the second electrode metal film 330A and the fourth electrode metal film 34
0A is bonded with the adhesive 140 {FIG. 4 (c)}. Next, the single crystal silicon substrate 430 is removed by etching using a potassium hydroxide solution or an ethylenediamine solution {FIG. 4 (d)}. Next, the thin film piezoelectric element is shaped into a predetermined shape by dry etching or the like (FIG. 4).
(E)}. Next, the surface on which the thin film piezoelectric element is formed on the single crystal silicon substrate 440 is covered with the coating resin 150 to prevent damage and deterioration of the thin film piezoelectric element {FIG.
(F)}, the last remaining single crystal silicon substrate 440
Is etched with a potassium hydroxide solution or an ethylenediamine solution, and the magnesium oxide film 520A formed on the single crystal silicon substrate 440 is removed with phosphoric acid {FIG. 4 (g)}, a pair of thin film piezoelectric elements. 10
A thin film piezoelectric element 100 composed of 0A and 100B is obtained.

The step of forming a first terminal for applying a drive voltage to the first electrode metal film 310A and the third electrode metal film 320A, and the second electrode metal film 330A and the fourth electrode metal film.
Illustration of the step of forming a ground voltage on the electrode metal film 340A is omitted.

In this embodiment, the single crystal silicon substrate may be provided with a thermal oxide film or without a thermal oxide film. Even a substrate without a thermal oxide film has a natural oxide film of several nm on its surface.
It is because it is formed. However, in order to enhance the reproducibility of the process, it is preferable to use a substrate with a thermal oxide film.

In the thin film piezoelectric element thus obtained, the magnesium oxide film having a thickness of 200 nm preferentially oriented on the (200) plane remains. Even if the magnesium oxide film having such a film thickness remains, the displacement amount of the thin film piezoelectric body is not significantly affected, but a larger displacement amount can be obtained without the magnesium oxide film. Therefore, in the thin film piezoelectric element manufacturing process, for example, by removing the single crystal silicon substrate 430 and then immersing the element in a phosphoric acid solution, the first magnesium oxide film 510 is formed.
A device in which A is also removed can be obtained. In this embodiment mode, after removing the single crystal silicon substrate 440, the second
Although the electrode metal film 320A of No. 1 was removed, it is also possible to leave it without removing it. In short, whether to remove both layers of the magnesium oxide film, only one layer, or not to remove them may be determined according to the required displacement amount and cost.

By using the thin film piezoelectric element manufactured as described above in the head supporting mechanism for supporting the magnetic head in the magnetic disk device, the magnetic head can be positioned with high accuracy and at high speed.

[0035]

As described above, according to the first and sixth aspects of the invention, an inexpensive and large-diameter silicon substrate is used in place of the conventional expensive and small-diameter magnesium oxide single crystal substrate, and the efficiency is improved. It is possible to provide a highly reliable thin film piezoelectric element capable of minutely displacing the head.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a thin film piezoelectric element.

FIG. 2 is a sectional view taken along line X-X ′ of FIG.

3A to 3G are diagrams illustrating an example of a conventional method for manufacturing a thin film piezoelectric element.

4 (a) to 4 (g) are diagrams illustrating a method of manufacturing a thin film piezoelectric element according to the present invention.

FIG. 5 is a plan view showing an example of a thin film piezoelectric element according to the present invention.

[Explanation of symbols]

150 coating resin 210A First thin film piezoelectric body 220A Second thin film piezoelectric body 310A First electrode metal film 320A Second electrode metal film 330A Third electrode metal film 340A Fourth electrode metal film 430 First silicon substrate 440 Second silicon substrate 510A First magnesium oxide film 520A Second magnesium oxide film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 41/18 H01L 41/22 Z 41/22 41/18 101Z (72) Inventor Hiroyuki Kita Kadoma City, Osaka Prefecture Daiji Kadoma 1006 Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideki Kuwashima Osaka Kadoma City Kadoma City 1006 Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideo Torii Osaka Kadoma City Kadoma 1006 Matsushita Electric Industrial Co., Ltd. In-house F-term (reference) 5D042 LA01 MA15 5D059 AA01 BA01 CA18 DA19 DA26 DA33 EA08 5D096 NN03 NN07

Claims (7)

[Claims] 1. A laminated body in which a first electrode metal film (310A), a first thin film piezoelectric body (210A) and a second electrode metal film (330A) are laminated in this order, and a third electrode metal film (320).
A), the second thin film piezoelectric material (220A), and the fourth metal film (34)
0A) and the second electrode metal film (330A) and the fourth electrode metal film (340).
A) and at least a part of it is bonded with resin (15
0), a first terminal for applying a driving voltage to the first electrode metal film (310A) and the third electrode metal film (320A), and the second electrode metal film (330).
A) A thin film piezoelectric element having a second terminal for applying a ground voltage to the fourth electrode metal film (340A), comprising at least the first electrode metal film (310A) or the third electrode metal. A magnesium oxide film (510A, 520A) preferentially oriented on the (200) plane is formed on one surface of the film (320A) on which the thin film piezoelectric material (210A, 220A) is not formed. Characteristic thin film piezoelectric element. 2. The magnesium oxide film (510A, 5A)
The thin film piezoelectric element according to claim 1, wherein the film thickness of 20 A) is 10 nm or more and 500 nm or less. 3. The thin film piezoelectric element according to claim 1, wherein the first electrode metal film (310A) and the third electrode metal film (320A) are Pt films. 4. The second electrode metal film (330A) and the fourth electrode metal film (340A) are made of Pt, Ta, Au,
The thin film piezoelectric element according to claim 1, wherein the thin film piezoelectric element is a laminated film including at least two kinds of metal films selected from Rh, Cu, Ti, and Cr. 5. The thin film according to claim 1, wherein the first thin film piezoelectric body (210A) and the second thin film piezoelectric body (220A) are made of a lead-based piezoelectric material. Piezoelectric element. 6. A first substrate in which a first electrode metal film (310A), a first thin film piezoelectric body (210A) and a second electrode metal (330A) are laminated in this order on a first substrate (430). A step of producing and a second substrate in which a third electrode metal film (320A), a second thin film piezoelectric body (220A) and a fourth electrode metal (340A) are laminated in this order on a second substrate (440). And the first base and the second base are bonded together by the second electrode metal film surface (330A) and the fourth metal electrode film surface (340A). The substrate (430) is removed by etching, and the first electrode metal film (310A), the first thin film piezoelectric body (210A), the second electrode metal film (330A), and the fourth electrode metal film (340A). And the second thin film piezoelectric body (220A) and the third electrode metal film (3 20A) are processed into a predetermined shape, and at the same time, the first electrode metal film (310A) and the third electrode metal film (310A)
A first terminal for applying a driving voltage to the electrode metal film (320A) is formed, and a first terminal for applying a ground voltage to the second electrode metal (330A) and the fourth electrode metal film (340A). A step of forming two terminals and a step of forming a thin film piezoelectric element by removing the second substrate (440) after performing a coating treatment with a resin (150) for preventing an adverse effect from the external environment. The first substrate (4
30) and as the second substrate (440), a magnesium oxide film (5) preferentially oriented on the (200) plane is formed on the surface.
10A, 520A) is used to form a single crystal silicon substrate, and a method for manufacturing a thin film piezoelectric element. 7. A thin film piezoelectric element for a hard disk drive having the structure according to claim 1. Description: