JP3282085B2 - Method for manufacturing piezoelectric / electrostrictive film element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various sensors such as filters, acceleration sensors and shock sensors, transformers, microphones, sound generators (such as speakers), oscillators and oscillators for power and communication, and displays and the like. Kenji Uchino (edited by Japan Industrial Technology Center) "From the Basics to Applications of Piezoelectric / Electrostrictive Actuators" (Morikita Publishing), Unimorph type actuators that generate bending displacement used in relays, servo displacement elements, etc. The present invention relates to a piezoelectric / electrostrictive film element which converts electric energy into mechanical energy, that is, converts mechanical energy into mechanical displacement or stress or vibration, and vice versa. Further, since the element manufactured according to the present invention has not only piezoelectric / electrostrictive properties but also dielectric properties, it can be used as a film-shaped capacitor element or the like.

[0002]

2. Description of the Related Art In recent years, in the fields of optics and precision machining, a displacement element for adjusting an optical path length and a position on the order of submicrons and a detection element for detecting a minute displacement as an electrical change have been desired. In response to this, the development of devices that use the reverse piezoelectric effect or the displacement based on the electrostrictive effect that occurs when an electric field is applied to a piezoelectric / electrostrictive material such as a ferroelectric material or the opposite phenomenon is being promoted. ing.

In such a field, in an actuator or the like, a conventionally known unimorph-type bending displacement type is suitably used as an element structure, and the printing quality and printing speed of a printer are improved. In order to respond to the demand for improvement, developments for miniaturization, high-density operation, low-voltage operation, and high-speed response of devices have been promoted.

In order to improve such characteristics, it is considered important to reduce the thickness of a substrate serving as a diaphragm of an element, and the applicant of the present application disclosed in the prior application (Japanese Patent Laid-Open No. 5-49270)
A first ceramic substrate having a hole or a missing portion and a thin and flat second substrate are laminated in a green sheet state, and the outer surface of a concave portion formed by closing the hole or the missing portion is formed on the first ceramic substrate. A piezoelectric / electrostrictive actuator in which a piezoelectric / electrostrictive operating portion (hereinafter, abbreviated as an operating portion) is formed on the substrate and only the portion serving as a diaphragm is made thin. According to such a structure, only the portion functioning as the actuator is thin and the thickness between the operating portions is thick, so that sufficient strength can be ensured as a whole of the ceramic substrate, and between the operating portions. It is easy to suppress the interference of vibration at the time. Further, a plurality of operating portions are formed on the same ceramic substrate surface with such a ceramic substrate structure, and a reduction in displacement when simultaneously operating each operating portion is reduced. In order to prevent the characteristics of the material itself from deteriorating, an element having a groove formed from the surface of the thick portion of the ceramic substrate to a portion deeper than the thickness of the thin portion (diaphragm) along the inner wall of the hole or the missing portion is used. Developed (Japanese Patent Application 5-16
3945).

[0005]

However, subsequent studies have revealed that the following problems exist when realizing an element structure in which the grooves are formed. Groove processing that is deeper than the thickness of the thin portion (diaphragm) is roughly divided into a method in which a ceramic substrate having a hole or a missing portion formed therein and a ceramic substrate laminated thereon are each performed in the state of a green sheet. There is a method which is performed after firing the ceramic substrate, or a method which is performed after firing each ceramic substrate and forming the operating portion. The element grooved by each method,
As compared with an element having no groove, the displacement reduction rate and the material characteristics of the piezoelectric / electrostrictive film material when a plurality of operating parts are simultaneously operated on the same ceramic substrate surface are improved. But,
The method of processing the grooves in advance in a state in which each ceramic substrate is a green sheet is advantageous in that the processing speed is faster than the case of processing after firing, but each ceramic substrate is fired to form a piezoelectric / electrostrictive operation portion. Compared with the method of forming grooves later, the rate of reduction in displacement when a plurality of operating parts are simultaneously operated on the same ceramic substrate surface is the same, but the degree of improvement in the material characteristics of the piezoelectric / electrostrictive film is I found it small. Also, in the method of forming a groove after firing the ceramic substrate, that is, before forming the piezoelectric / electrostrictive film operating portion, the material characteristics of the piezoelectric / electrostrictive film can be improved in the same manner as in the case of the green sheet state. The degree was found to be small. That is, they have found that it is preferable to form the groove after forming the piezoelectric / electrostrictive film operating portion.

On the other hand, in order to further improve the material properties, it is preferable to make the groove deep, and a large effect can be obtained by performing deep groove processing on the fired ceramic substrate. However, when many operation parts are formed on the same ceramic substrate surface as an actuator of an ink jet print head, for example, and the application to a high-density one is considered, the pitch between the operation parts is small and very thin. Since the diaphragm is made of a thin diaphragm, there is a problem that the damage due to the groove processing is large, and there is a high possibility that the diaphragm or the like is cracked. Further, when comparing the substrate after firing and the substrate in a green sheet state, the substrate after firing may be deformed due to the firing strain, or a phenomenon such as undulation may remain on the substrate. When there is a variation in the processing surface, for example, when processing is performed by a laser, the focal point varies, thereby changing the processing depth. On the other hand, if the processing is advanced while constantly monitoring the focus, it is possible to absorb the variation, but the processing speed is reduced and the productivity is reduced. Therefore, if the grooves are formed in a state where each substrate is a green sheet as described above, such a problem does not occur.
Another problem arises in that the degree of improvement in the material properties of the electrostrictive film is small.

Therefore, an object of the present invention is to prevent the occurrence rate of defects from increasing even when the operating portion is densified, without significantly reducing the reliability and productivity.
To provide a piezoelectric / electrostrictive film type element having a small displacement reduction rate when a plurality of operating parts are simultaneously operated. In particular, even if a heat treatment for integrating a ceramic substrate and an operating part is performed, An object of the present invention is to provide a piezoelectric / electrostrictive film type element in which the rate of reduction in the material characteristics of the electrostrictive material is small.

[0008]

According to the present invention, which can achieve the above object, at least one window having a predetermined size is formed and at least one window having an appropriate length is formed. A first sheet-like ceramic member in a green sheet state, the grooves of which are formed along the inner wall surface of the window portion and at appropriate intervals from the inner wall surface;
A second green plate-like second flat ceramic member that closes the windows and the first grooves is laminated on at least one surface of the first ceramic member. A ceramic substrate is formed by firing and integrating, and then a piezoelectric / electrostrictive operation comprising a lower electrode film, a piezoelectric / electrostrictive film and an upper electrode film is formed on the bottom outer surface of each closed window of the ceramic substrate. The part is formed by firing and integrating with the ceramic substrate, and thereafter, a second groove communicating with each of the first grooves is formed from an outer surface of the thick part of the ceramic substrate.

In addition, the thin second plate-shaped ceramic member is laminated on one surface of the first plate-shaped ceramic member, and the third plate-shaped ceramic member is laminated on the other surface. To form the ceramic substrate.

In order to further enhance the effects of the present invention, it is preferable that the ceramic substrate is made of a material containing zirconium oxide as a main component, which is completely or partially stabilized.

The piezoelectric / electrostrictive film may be made of a material mainly composed of lead magnesium niobate, lead zirconate and lead titanate, or lead nickel niobate and lead magnesium niobate and lead zirconate. A material mainly composed of a component composed of lead titanate, or a material mainly composed of a component composed of lead nickel tantalate and lead magnesium niobate and lead zirconate and lead titanate,
Alternatively, it is desirably made of a material mainly composed of components of lead magnesium tantalate, lead magnesium niobate, lead zirconate and lead titanate.

Further, the thickness of the thin portion of the ceramic substrate is desirably 50 μm or less.

Furthermore, it is desirable that the groove is formed by an excimer laser or a YAG laser.

[0014]

In order to previously process the first groove in the first sheet-like ceramic member in the green sheet state forming the window,
The depth of the second groove processing from the outer surface of the ceramic substrate after firing may be the thickness of the second ceramic member, and it is not necessary to process the groove with high energy beyond the thickness of the second ceramic member. Finally, since the groove is closed by the second ceramic member, it is necessary to process the second groove communicating with the groove of the first ceramic member. However, since the second ceramic member is thin, Since the groove processing can be performed at high speed and with low energy, damage to a thin portion (diaphragm) and the like can be suppressed due to the low energy, and cracks and cracks may occur in the thin portion of the ceramic substrate. Few.
Further, since the first groove to be processed into the first ceramic member corresponds to the lowermost part of the finally formed groove, if the depth is made constant, the depth of all the finally formed grooves is increased. Since the first ceramic member is processed in a green sheet state, that is, in a state in which the first ceramic member can be easily processed, the lowermost part can be easily unified. Can be reduced. That is, each of the operating portions is integrated by heat treatment in the ceramic substrate having substantially no groove, and the subsequent groove processing can advantageously reduce the deterioration of the piezoelectric / electrostrictive material properties, Moreover, the groove processing itself is advantageous in that the occurrence of the defective element and the processing speed can be improved.

The thickness of the ceramic member preferably employed in forming the element according to the present invention is 5 times as large as that of the first ceramic member forming the window and the first groove.
0 μm or more, more preferably 100 μm or more in thickness,
In addition, it is desirable that the thickness of the second ceramic member laminated on the first ceramic member is 50 μm or less, more preferably 3 to 20 μm. The third ceramic member is desirably formed with a thickness of 10 μm or more, preferably 50 μm or more.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a device according to the present invention will be described in detail with reference to the drawings. To facilitate understanding, the same reference numerals are given to components having the same structure and function throughout the drawings. 1 and 2 are explanatory views showing a method for manufacturing a device of the present invention, and FIG. 4 is a flowchart showing a manufacturing process. In FIG. 1, (8) is a plate-shaped first ceramic member in a green sheet state, (4) is a thin and flat second ceramic member in a green sheet state, and (7) is a plate-shaped green ceramic state member. This is a third ceramic member. The hole (7b) formed in the third ceramic member (7) is a hole for allowing gas and liquid to flow into and out of the cavity when used in a sensor or the like. As shown in FIG. 1, first, a plurality of windows are provided on a first ceramic member (8).
(5), and (5) are formed through the first groove (6) on both sides of each window.
a) is formed along the inner wall surface (8b) of the window (5) and at an appropriate distance from the inner wall surface. Next, a second ceramic member (4) is laminated on the front surface of the first ceramic member (8), and a third ceramic member (7) is laminated on the back surface. Then, the laminated ceramic members are fired and integrated to form a ceramic substrate (14) (FIG. 2 (b)).
Next, a lower electrode film, a piezoelectric / electrostrictive film, and an upper electrode film are formed on the surface corresponding to the upper opening surface of each window (5) and on the outer surface of the ceramic substrate (14), that is, the surface serving as a diaphragm. An operating portion (2) consisting of three layers is formed by a film forming method described later, and the operating portion (2) and the ceramic substrate (14) are integrated by firing (FIG. 2 (c)). Next, the window of the ceramic substrate (14)
The thick portions formed on both sides of (5), that is, (7a) of the third ceramic member (7), (8a) of the first ceramic member (8), and of the second ceramic member (4). A second groove (6) is inserted into a portion corresponding to the first groove (6a) on the outer surface of the portion composed of (4b).
b) is processed so as to communicate with the first groove (6a), and a target element is completed. FIG. 3 is an explanatory sectional view of the completed device taken along the line AA in FIG. 2 (d). The first groove as shown
(6a) and the second groove (6b) form the final groove (6).

The length of the groove (6) (FIG. 1 (a) and FIG.
1)) is at least 1/8 or more, preferably 1/4 or more, of the longitudinal side edge of the window (5) along the groove, and the longitudinal center of the groove is the window (5). Is preferably formed on an extension from the center of the side edge in the longitudinal direction. The depth (D3) of the groove (6) shown in FIG. 3 is at least the thickness (D1) of the diaphragm (4a).
It is desirable to form the layer so as to have a depth exceeding, and preferably, a depth shown by the following equation (1). Note that a plurality of holes (7b) may be formed according to the purpose.

[0018]

D1 ≧ D2 / 4 + D1

More preferably, it is desirable to form the layer so as to have a depth represented by the following equation (2).

[0020]

## EQU2 ## D3 ≧ D2 / 2 + D1

The shape of the groove may be V-shaped, trapezoidal, or the like, in addition to that formed in the direction perpendicular to the substrate surface as in this embodiment.

The surface on which the operating portion is formed, that is, the diaphragm (4
The thickness a) is generally 50 μm or less, preferably 3 to 20 μm, in order to obtain a high-speed response and a large displacement of the operating portion.

Further, the thickness of the third ceramic member is 1
It is formed to a thickness of 0 μm or more, preferably 50 μm or more.

As described above, according to the method of manufacturing the element of the present invention, the groove of the portion exceeding the thickness of the second ceramic member, that is, the lowermost part of the finally formed groove is formed in advance by the first ceramic in a green sheet state. Since it is necessary to perform shallow processing with low energy compared to a method of processing the entire groove after firing both members, it is less likely that cracks and cracks are generated in the thin diaphragm. Can be processed at high speed. In addition, since the lowermost portion of the groove is formed in the first ceramic member in a green sheet state, processing is easy, and the final depth of the groove can be made substantially constant. Even when a plurality of operating parts are provided, it is possible to reduce variations in characteristics among the operating parts.

FIG. 5 is an explanatory perspective view showing the appearance of a device manufactured according to the present invention, and FIG. In FIG. 5, (1) shows an element in which a plurality of operating parts (2),... (2) are formed in a zigzag pattern on the ceramic substrate (14) manufactured in the above process, and in FIG. Lower electrode film, (2
b) shows a piezoelectric / electrostrictive film, and (2c) shows an upper electrode film. Fig. 6 (b)
As shown in the figure, the groove formed deeper than the thickness of the diaphragm (4a)
(6) Each diaphragm is easily bent greatly due to the improved material properties of the piezoelectric / electrostrictive film, and with the displacement of the diaphragm,
Since the inner walls (8b) and (8b) of the cavity (5a) are also displaced inward, the volume change in the cavity can be performed easily and quickly as compared with the conventional one in which only the diaphragm is displaced. Also, even when a plurality of operating parts operate simultaneously, the force of pulling the diaphragms is buffered by the grooves, and the depth of the grooves is constant, so that the variation in the displacement of each diaphragm is reduced. Can be. Furthermore, when the structure in which the operating portions are arranged in a staggered manner as shown in FIG. 5 is used, the front and rear grooves are not located on the extension line in the longitudinal direction, as compared with a structure in a non-staggered and symmetrical arrangement. The decrease in overall mechanical strength is small, and the substrate does not undulate even when handling is performed.

Incidentally, even in the case of an element in which a closed substrate (third ceramic member) as shown in FIG. 7 is not formed, a first groove is previously formed in the first ceramic substrate in a green sheet state. If the second groove is formed on the ceramic substrate after laminating the second ceramic member and firing and integrating the operating portion, an element having the same effect as that having the closed substrate can be manufactured.

As shown in FIG. 8, two first grooves are formed in the first ceramic member, and two second grooves communicating with the first grooves are formed on the outer surface of the ceramic substrate. It is also possible to manufacture an element in which two grooves exceeding the thickness of the first ceramic member (diaphragm) are finally formed by processing. According to this structure, even when the pitch between the operation parts is wide and the width of the thick part is designed wide, the rigidity of the substrate around the operation part can be reduced by forming a plurality of grooves. Compared with the element having one groove, more excellent element characteristics can be obtained, which is preferable.

FIG. 9 (a) is a cross-sectional view of a device manufactured according to the present invention by applying the operating portion of the device proposed by the present applicant in an earlier application (Japanese Patent Application No. 5-75414). The working part covers the piezoelectric / electrostrictive film (9b) on the lower electrode film (9a), and covers the lower electrode film, and has an end on the ceramic substrate (14), as shown in FIG. It is a structure that is oversized. An incomplete joint (11) is formed between the overhang (10) and the ceramic substrate (14). Here, the incompletely connected portion refers to a connection state in which the connection between the overhang portion (10) and the ceramic substrate (14) is incomplete and the operating portion (9) can sufficiently exhibit the required performance. . (12) Smooth the upper electrode film on the ceramic substrate to prevent disconnection of the upper electrode film (9c).
(14) It is a resin layer formed to lead on. This device facilitates the alignment of the lower electrode film, the piezoelectric / electrostrictive film, and the upper electrode film for preventing short circuit due to such a structure, and can improve the productivity of the device, as well as the overhanging portion and the ceramic. This prevents the piezoelectric / electrostrictive film from being bent or generated by being bonded to the substrate. Therefore, when the device is manufactured according to the present invention using the operating portion, not only the performance of the device but also the productivity of the device can be improved. In each of the above embodiments, the case where a plurality of operating portions are provided on the ceramic substrate has been described. However, even when only one operating portion is provided, a groove similar to the above may be formed in a thick portion of the substrate. Accordingly, the material characteristics of the piezoelectric / electrostrictive film can be sufficiently brought out, and as a result, the displacement increases as a result.

Next, in order to sufficiently exhibit the material characteristics of the piezoelectric / electrostrictive film of the element manufactured according to the present invention, the ceramic substrate contains a completely stabilized or partially stabilized zirconium oxide as a main component. Desirably, it is made of a material.

In order to completely or partially stabilize the zirconium oxide, an oxide of an alkaline earth element or a rare earth element can be used, as is generally known. Preferably, yttrium oxide is used. At least one of cerium oxide, magnesium oxide and calcium oxide is used. The addition amounts of yttrium oxide are 1 mol% to 30 mol%, and cerium oxide is 6 mol%.
It is preferable that the mol% to 50 mol% and the magnesium oxide and calcium oxide are 5 mol% to 40 mol%, and it is particularly preferable that the yttrium oxide is 2 mol% to 4 mol%. This is because zirconium oxide to which yttrium oxide is added in such a range has a partially stabilized crystal phase and exhibits particularly excellent substrate characteristics.

Although a sintering aid such as clay may be added to the substrate material, at least silicon oxide, boron oxide, phosphorus oxide, and oxide are contained in the second ceramic member constituting the thin portion. It is desirable to adjust the composition and amount of the auxiliary agent so that a material that easily becomes vitrified such as germanium is not contained in an amount of 1% by weight or more. This is because, if the material that easily becomes vitrified is contained in the ceramic substrate, a reaction easily occurs during heat treatment with the piezoelectric / electrostrictive film, and it becomes difficult to control the composition of the piezoelectric / electrostrictive film.

By the way, such a ceramic substrate is
In order to effectively receive the operating characteristics of the operating portion formed thereon, in other words, the distortion and force generated therein, and effectively perform the reverse operation, the surface roughness represented by Ra is 0.03 to 0.03. It is adjusted to be within the range of 0.9 μm.

The first groove formed in the first ceramic member is processed in a state of a green sheet, and in this case, various methods are adopted. Laser machining of YAG, excimer, carbon dioxide gas, etc. utilizing the first, second, fourth harmonics, etc., machining by dicing, slicing, ultrasonic waves, etc., stamping, punching by a mold, etc. are preferable. Adopted to. On the other hand, for the second groove processing on the ceramic substrate, the above-described various lasers, mechanical processing such as dicing and slicing, and the like are suitably adopted. Among these processing methods, laser processing such as YAG or excimer, which can easily perform relatively complicated processing, is preferably employed. In this case, in order to prevent cracks and cracks in the diaphragm, ,
It is necessary to minimize heat stress. In order to reduce this thermal stress, there are various conditions in processing. For example, in the case of performing the processing as in the present application, a YAG laser (for example, Nd-YAG) is used as a laser light source.
However, the pulse width is 140nsec or less, preferably 100nse.
c Below, pulse control by Q switch (for example, 3.6KH
z) is performed, and the beam diameter of the laser light is further reduced to φ50 μm or less, preferably φ5 to
It is desirable to adopt the single mode resonance of the TEM 00 so that φ10 μm, the processing speed is 50 mm / sec or less, and the Gaussian distribution (normal distribution) is obtained as the energy distribution in the laser beam.

A predetermined lower electrode film (2a), an upper electrode film (2c) and a piezoelectric / electrostrictive film are formed on such a ceramic substrate.
In order to form the operating portion (2) by providing (2b), various known film forming methods are appropriately adopted, for example, a thick film forming method such as screen printing, spraying, dipping, coating, and the like.
A thin film forming technique such as ion beam, sputtering, vacuum deposition, ion plating, CVD, and plating is appropriately selected. In particular, to form the piezoelectric / electrostrictive film (2b),
A method of forming a thick film by screen printing, spraying, dipping, coating, or the like is suitably adopted. Because, according to those thick film forming methods, the average particle diameter is 0.01
μm or more and 5 μm or less, preferably 0.05 μm or more and 3 μm
This is because a film can be formed on a ceramic substrate using a paste or a slurry mainly containing ceramic particles of the following piezoelectric / electrostrictive material, and good element characteristics can be obtained. In addition, as for the shape of such a film, in addition to forming a pattern using a screen printing method, a photolithography method, or the like, an unnecessary portion is removed by using a laser processing method, a slicing, or a mechanical processing method such as an ultrasonic processing. And may be patterned.

Each of the lower electrode film (2a), the piezoelectric / electrostrictive film (2b) and the upper electrode film (2c) constituting the piezoelectric / electrostrictive operating section (2) is formed by the above-mentioned various film forming techniques. As a method of forming the piezoelectric / electrostrictive operating portion (2) on the outer surface of the window of the ceramic substrate by firing and integrating with the ceramic substrate, any one of the following methods is appropriately selected. (A) After the lower electrode film (2a) is formed on the outer surface of the window of the ceramic substrate, the lower electrode film (2a) is fired and integrated with the ceramic substrate, and the piezoelectric film is formed on the fired and integrated lower electrode film (2a). Then, an upper electrode film (2c) is formed on the fired / integrated piezoelectric / electrostrictive film (2b) and integrated by firing. (B) The lower electrode film (2a), the piezoelectric / electrostrictive film (2b) and the upper electrode film (2c) are combined with the lower electrode film (2a), the piezoelectric / electrostrictive film (2b) and the upper electrode film (2c). After sequentially forming films on the ceramic substrate in order, they are collectively fired and integrated with the ceramic substrate. (C) The lower electrode film (2a) and the piezoelectric / electrostrictive film (2b) are sequentially formed on the ceramic substrate in the order of the lower electrode film (2a) and the piezoelectric / electrostrictive film (2b), and then they are formed on the ceramic substrate. And an upper electrode film on the fired piezoelectric / electrostrictive film (2b).
After forming (2c), they are fired and integrated. (D) After forming the lower electrode film (2a) on the ceramic substrate, the lower electrode film (2a) and the ceramic substrate are fired and integrated, and the piezoelectric / electrostrictive is formed on the fired lower electrode film (2a). film
(2b) and the upper electrode film (2c) are formed in the order of the piezoelectric / electrostrictive film (2b) and the upper electrode film (2c), and they are fired and integrated.

When the element shown in FIG. 9 is formed by using these methods of forming the operating portion, the protrusion (10) of the piezoelectric / electrostrictive film and the ceramic substrate (14) are incompletely connected. State. When an electrode film is formed by such a film forming method, heat treatment may not always be required for integration. For example, before forming the upper electrode film (2c), an insulating coat is applied around the element with an insulating resin or the like in order to ensure insulation with the lower electrode film (2a).
As described in (b), there is a case where a resin layer (12) for preventing disconnection of the upper electrode film (9c) is formed, in which case, the formation of the upper electrode film (9c) is performed. For this, a method such as vapor deposition, sputtering or plating that does not require heat treatment is employed.

Further, as a heat treatment temperature for integrating the thus formed film and the ceramic substrate, a temperature of about 900 ° C. to 1400 ° C. is generally employed, preferably 1000 ° C. to 1400 ° C. A temperature in the range C is advantageously selected. Further, when the piezoelectric / electrostrictive film is subjected to a heat treatment, the piezoelectric / electrostrictive layer is formed at a high temperature so that the composition of the piezoelectric / electrostrictive layer does not become unstable.
It is preferable to perform heat treatment while controlling the atmosphere together with the evaporation source of the electrostrictive material. It is also recommended that a suitable cover member be placed on the piezoelectric / electrostrictive film so that the surface of the cover member is not directly exposed to the firing atmosphere and firing is performed. In this case, a material similar to the ceramic substrate is used as the cover member.

The material of the lower electrode film (2a) constituting the operating portion manufactured by the above-mentioned method is not particularly limited as long as it is a conductor that can withstand the high-temperature oxidizing atmosphere of the heat treatment temperature and the firing temperature. Instead, for example, it may be a metal simple substance or an alloy, and an insulating ceramic,
A mixture with a metal or an alloy, or even a conductive ceramic may be used. More preferably, platinum, palladium, an electrode material mainly composed of an alloy such as high melting point noble metals such as rhodium, or silver-palladium, silver-platinum, platinum-palladium, platinum and a ceramic substrate material The cermet material of the above, a cermet material of platinum and a piezoelectric / electrostrictive material, and a cermet material of platinum, a substrate material and a piezoelectric material are suitably used, and among them, a material containing platinum as a main component is more preferable. Further, as a material to be added to the electrode, glass such as silicon oxide easily reacts during heat treatment with the piezoelectric / electrostrictive film, and tends to cause deterioration of actuator characteristics. Therefore, it is desirable to avoid using glass. The substrate material to be added to the electrode is preferably about 5 to 30% by volume, and the piezoelectric material is preferably about 5 to 20% by volume. On the other hand, the material of the upper electrode film is not particularly limited.

The electrode film formed by using such a conductive material is generally 20 μm or less, preferably 5 μm
It will be formed with the following film thickness.

As the piezoelectric / electrostrictive material constituting the operating portion, any material may be employed as long as it exhibits piezoelectric or electric-field-induced strain such as an electrostrictive effect. Even if it is a crystalline material, an amorphous material, or a semiconductor material, a dielectric ceramic material or a ferroelectric ceramic material, there is no problem. The material may need to be polarized or may be unnecessary.

The piezoelectric / electrostrictive material used in the present invention is preferably lead zirconate titanate (PZT).
) -Based material, lead magnesium niobate (P
MN-based material, lead nickel niobate (P
NN-based materials, materials based on lead magnesium tungstate, materials based on lead manganese niobate, materials based on lead antimony stannate, and materials based on lead zinc niobate Material, a material mainly composed of lead titanate, a material mainly composed of lead zirconate,
A material containing lead nickel tantalate as a main component, a material containing lead magnesium tantalate as a main component, and a composite material thereof are used. In addition, lanthanum, barium, niobium, zinc, cerium, cadmium,
Materials containing oxides such as chromium, cobalt, antimony, iron, yttrium, tantalum, tungsten, nickel, manganese, lithium, strontium, magnesium, calcium, bismuth, and other compounds as additives, such as PZT-based materials There is no problem even if lanthanum is added to a material containing as a main component and the above-mentioned additives are appropriately added to the material so as to be a PLZT-based material.
Note that addition of a glass material such as silicon oxide should be avoided. This is because a lead-based piezoelectric / electrostrictive material such as a PZT-based material easily reacts with glass, making it difficult to control the composition of a desired piezoelectric / electrostrictive film, causing variations and deterioration in actuator characteristics. .

Among these piezoelectric / electrostrictive materials, a material mainly composed of components of lead magnesium niobate, lead zirconate and lead titanate, or lead nickel niobate, lead magnesium niobate and lead zirconate, Material mainly composed of lead titanate, or material mainly composed of lead nickel tantalate and lead magnesium niobate, lead zirconate and lead titanate, or lead magnesium tantalate and magnesium niobate A material mainly composed of components consisting of lead and lead zirconate and lead titanate is preferable, and furthermore, a material mainly composed of components composed of lead magnesium niobate and lead zirconate and lead titanate is particularly preferable. Since the reaction with the substrate material during the heat treatment is particularly small, for example, In addition to keeping the bonding state between the metal part and the ceramic substrate low enough not to affect the required performance of the piezoelectric / electrostrictive operating part, segregation of the components is unlikely to occur, and the processing for maintaining the composition is difficult. It is advantageously used in combination with having a high piezoelectric constant, such as being able to be suitably carried out and easily obtaining a target composition and a crystal structure, and is used in a thick film forming technique such as screen printing, spraying, dipping, and coating. It is recommended as a material for forming an electrostrictive film. In the case of a multi-component piezoelectric / electrostrictive material, the piezoelectric characteristics change depending on the composition of the components. However, in the three-component material of lead magnesium niobate-lead zirconate-lead titanate that is suitably employed in the present invention, The composition is preferably in the vicinity of the phase boundary of pseudo-cubic-tetragonal-rhombohedral, particularly lead magnesium niobate: 15 mol% to 50 mol%, lead zirconate: 10 mol% to 45 mol.
Mole%, lead titanate: A composition of 30 mol% to 45 mol% is advantageously employed because it has a high piezoelectric constant and an electromechanical coupling coefficient.

Further, the thickness of the operating portion composed of the electrode film and the piezoelectric / electrostrictive film formed as described above is generally 100 μm or less, and the thickness of the piezoelectric / electrostrictive film is In order to obtain a large displacement or the like at a low operating voltage, the thickness is preferably 50 μm or less, more preferably 3 μm or more and 40 μm or less.

Furthermore, the structure of the element manufactured here and the shape of the film-shaped operating portion are not limited at all, and any shape can be adopted according to the application, for example, a triangle, a square, etc. Even if it is a circular shape such as a polygon, a circle, an ellipse, a ring, a comb shape, a lattice shape, or a special shape obtained by combining them, there is no problem at all, and the groove formed in the thick portion also has a shape corresponding to the shape of the operating portion. By correspondingly forming, the effect of the present invention can be obtained.

Next, the effects of the present invention will be described based on experimental results. This experiment was conducted by manufacturing an element having the same working part on a substrate (15) as shown in FIG. 10 by three methods, and the displacement change rate of the working part, relative dielectric constant, number of cracks and The processing speed was measured. One of the three methods is to form a working part after laminating a first ceramic member and a second ceramic member, forming a groove in both members in the state of a green sheet, and firing the green member. (Comparative example 1), the other is a groove formed after firing and integration of the operating portion and the ceramic substrate (Comparative example 2), and the other is by the manufacturing method of the present invention (the present application). ). The element structure is such that five operating portions are arranged in a row on the same surface of a ceramic substrate. The ceramic substrate has a second ceramic member serving as a diaphragm having a thickness of 10 μm and a window portion. The thickness of the first ceramic member forming the first ceramic member was set to 150 μm, and the thickness of the third ceramic member facing the second ceramic member was set to 200 μm. A window part of a ceramic substrate forming an operating part,
That is, the dimension of the thin portion is 0.5 × 2 mm, and the pitch between the working portions is 0.6 mm. The operating part is P for the lower electrode film material.
t for the piezoelectric / electrostrictive film material,
A material made of lead zirconate-lead titanate and having a relative dielectric constant of 4300 in bulk and Au as an upper electrode film material was formed by a thick film method, and each groove was processed by a YAG laser. The displacement of each operating part was measured by evaluating the displacement when a voltage of 30 V was applied to each operating part individually or simultaneously with a laser Doppler vibrometer.

[0046]

[Table 1]

As is clear from Table 1 showing the experimental results, the manufacturing method according to the present invention has a small displacement change rate of the operating portion, and the number of cracks generated in the groove forming step is as follows.
Dramatically less than the method of Comparative Example 2, almost the same as the method of Comparative Example 1, and it can be seen that there is almost no occurrence of defects due to processing. Also, it can be seen that the processing speed of the groove is slower than the method of Comparative Example 1, but is overwhelmingly faster than the method of Comparative Example 2. On the other hand, the relative permittivity is slightly smaller than the method of Comparative Example 2, but is considerably larger than the method of Comparative Example 1.
That is, it is understood that the degree of improvement in the material characteristics of the piezoelectric / electrostrictive film is large. As described above, according to the present invention, even when the operating parts are densified, a plurality of operating parts can be operated at the same time without increasing the defect occurrence rate and without significantly reducing the reliability and productivity. In this case, it is possible to improve the reduction rate of displacement and the reduction rate of the material properties of the piezoelectric / electrostrictive film.

The present invention is not limited to the above embodiments, but may be changed, modified or improved without departing from the scope of the present invention.

[0049]

According to the present invention, since the lowermost portion of the groove is previously formed in the first ceramic member in the green sheet state forming the window, the groove is formed from the fired outer surface of the ceramic member. Since the depth may be the thickness of the thin second ceramic member, that is, the thickness of the diaphragm, there is no need to machine the groove beyond the thickness of the second ceramic member with high energy after forming the operating portion, and Cracks and cracks are less likely to occur on the diaphragm during processing. In addition, since the depth of the entire groove can be determined by processing the groove in the first ceramic member in the green sheet state, the control of the groove depth is easier and more accurate than the method of processing the entire groove after firing. In addition, it is advantageous for the displacement of the machining position, and is therefore effective for reducing the variation in the characteristics between the operating parts. As described above, according to the present invention, even when the operating portion is densified,
Improvement of the displacement reduction rate and the material property reduction rate of the piezoelectric / electrostrictive film when multiple operating parts are operated at the same time without increasing the defect occurrence rate and without significantly reducing the reliability and productivity. Can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a method for manufacturing an element according to the present invention.

FIG. 2 is an explanatory view showing a method for manufacturing an element according to the present invention.

FIG. 3 is an explanatory sectional view taken along the line AA of FIG. 2 (d).

FIG. 4 is a flowchart showing a method for manufacturing an element according to the present invention.

FIG. 5 is an explanatory diagram of an element manufactured by a method for manufacturing an element according to the present invention.

6 (a) is an explanatory view of a section taken along line BB of FIG. 5, and FIG. 6 (b) is an explanatory view of a displaced element.

FIG. 7 is an explanatory view of an element without a closed substrate.

FIG. 8 is an explanatory diagram of an element in which a plurality of grooves are formed.

FIG. 9 is an explanatory diagram of an element in which a piezoelectric / electrostrictive film is formed so as to protrude.

FIG. 10 is an explanatory diagram of an element used in an experiment.

[Description of Signs] 1. Element, 2, 9 working part, 2a, 9a lower electrode film, 2b, 9b piezoelectric / electrostrictive film, 2c, 9c upper electrode film, 7a, 8a ..Thick part, 8b..Inner wall surface, 4
..The second ceramic member, 7 the third ceramic member, 8 the first ceramic member, 4a the diaphragm,
..Window portion, 6 groove, 6a first groove, 6b second
Groove, 10 ... overhang, 11 ... imperfect connection, 1
2..Resin layer, 14,15..Ceramic substrate.

Continuation of the front page (56) References JP-A-63-149159 (JP, A) JP-A-6-252464 (JP, A) JP-A-6-350155 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) H01L 41/22 H01L 41/09

Claims (6)

(57) [Claims] At least one window portion having a predetermined size is formed, and at least one first groove having an appropriate length is formed along an inner wall surface of the window portion and from an inner wall surface thereof. A first plate-like ceramic member in a green sheet state formed at an appropriate interval, and a thin-walled member for closing the windows and the first groove on at least one surface of the first plate-like ceramic member. Laminating a second flat ceramic member in a green sheet state, and firing and integrating the laminated ceramic members to form a ceramic substrate;
Next, a piezoelectric / electrostrictive operating portion including a lower electrode film, a piezoelectric / electrostrictive film, and an upper electrode film is fired and integrated with the ceramic substrate on the bottom outer surface of each closed window of the ceramic substrate. Forming a second groove communicating with each of the first grooves from the outer surface of the thick portion of the ceramic substrate. 2. The second plate-shaped ceramic member is provided on one surface of the first plate-shaped ceramic member, and the third plate-shaped ceramic member is provided on the other surface.
2. The method for manufacturing a piezoelectric / electrostrictive film element according to claim 1, wherein said ceramic substrate is formed by laminating said plate-shaped ceramic members and integrating them by firing. 3. The method for manufacturing a piezoelectric / electrostrictive film element according to claim 1, wherein said ceramic substrate is made of a material containing zirconium oxide as a main component, which is completely or partially stabilized. 4. A piezoelectric / electrostrictive film according to claim 1, wherein said piezoelectric / electrostrictive film is made of a material mainly composed of lead magnesium niobate, lead zirconate and lead titanate, or lead nickel niobate, lead magnesium niobate and lead zirconate. Material mainly composed of lead titanate, or material mainly composed of lead nickel tantalate and lead magnesium niobate, lead zirconate and lead titanate, or lead magnesium tantalate and magnesium niobate 4. The method for manufacturing a piezoelectric / electrostrictive film type device according to claim 1, wherein said piezoelectric / electrostrictive film type device is made of a material mainly containing a component consisting of lead, lead zirconate and lead titanate. 5. The ceramic substrate according to claim 1, wherein said thin portion has a thickness of 50.
5. The method for manufacturing a piezoelectric / electrostrictive film type device according to claim 1, wherein the thickness is not more than μm. 6. The groove is formed by an excimer laser or YAG.
6. The method for manufacturing a piezoelectric / electrostrictive film type device according to claim 1, wherein the device is formed by a laser.