JP2007013009A - Piezoelectric element, electronic device and electronic equipment - Google Patents

Abstract

A piezoelectric element capable of exhibiting excellent characteristics over a long period of time, an electronic device including the piezoelectric element, and an electronic apparatus including the electronic device are provided.
A piezoelectric element 4 of the present invention includes a piezoelectric body 41 mainly composed of a piezoelectric material, and a pair of electrodes 42, 43 joined to the piezoelectric body 41. The piezoelectric body 41 is configured to be displaced or deformed by applying a voltage thereto, and at least a part of the piezoelectric body 41 to which the electrodes 42 and 43 are attached is mainly made of an inorganic material. The film 44 is covered, and at least a part of the protective film 44 is subjected to water repellent treatment.
[Selection] Figure 3

Description

  The present invention relates to a piezoelectric element, an electronic device, and an electronic apparatus.

For example, an electronic device such as an inkjet head is provided with a piezoelectric element in order to obtain the driving force (see, for example, Patent Document 1).
Such a piezoelectric element is formed, for example, by interposing a piezoelectric body composed mainly of a piezoelectric material between a pair of electrodes. Since the characteristics of the piezoelectric body are likely to deteriorate due to moisture or moisture such as a chemical solution used in the manufacturing process, for example, in Patent Document 1, a protective film is formed so as to cover the piezoelectric body.

This protective film is made of an inorganic material in order to have excellent durability and water barrier properties. Further, the protective film needs to be as thin as possible so as not to hinder the displacement of the piezoelectric body.
However, when a protective film made of an inorganic material is thinly formed as described above, a defective portion such as a pinhole or a crack is generated, and the water barrier property of the protective film may be impaired. As a result, it is difficult for the piezoelectric element according to Patent Document 1 to exhibit excellent characteristics over a long period of time due to the penetration of moisture from the defect portion.

JP-A-11-235818

  An object of the present invention is to provide a piezoelectric element that can exhibit excellent characteristics over a long period of time, an electronic device including the piezoelectric element, and an electronic apparatus including the electronic device.

Such an object is achieved by the present invention described below.
The piezoelectric element of the present invention includes a piezoelectric body mainly composed of a piezoelectric material,
A pair of electrodes joined to the piezoelectric body;
A piezoelectric element configured to displace or deform the piezoelectric body by applying a voltage to the pair of electrodes,
At least a part of the piezoelectric body provided with the electrode is covered with a protective film mainly composed of an inorganic material,
A water repellent treatment is performed on at least a part of the protective film.

Thereby, even if a defect part such as a pinhole or a crack occurs in the protective film, moisture such as a chemical solution used in the manufacturing process can be prevented from entering through the defect part. As a result, deterioration of the characteristics of the piezoelectric body due to moisture can be prevented, and the characteristics of the piezoelectric element can be made excellent over a long period of time.
In other words, even with a thin protective film that is prone to defects such as pinholes and cracks, the deterioration of the piezoelectric characteristics due to moisture should be reliably prevented, and the characteristics of the piezoelectric element should be excellent over a long period of time. Can do. Such a thin protective film can minimize the hindrance to displacement of the piezoelectric body, so that the characteristics of the piezoelectric element can be improved.

In the piezoelectric element of the present invention, it is preferable that the piezoelectric body is interposed between the pair of electrodes.
Thereby, the piezoelectric element of the present invention can be applied to a piezoelectric element. The present invention reduces the thickness of the protective film and reduces the responsiveness of the displacement of the piezoelectric body while preventing the deterioration of the piezoelectric body due to moisture even when the displacement amount of the piezoelectric body is large, such as a piezo element. It can be excellent. Thus, the present invention is particularly effective when the displacement of the piezoelectric body is large and cracks are likely to occur in the protective film, such as a piezo element.

In the piezoelectric element of the present invention, it is preferable that the water repellent treatment is to inject ions that can impart water repellency into the protective film.
Thereby, water repellent treatment can be performed on the protective film while suppressing the thickness of the protective film. In this case, since the protective film is thin, the response of displacement of the piezoelectric body can be further improved.
In the piezoelectric element of the present invention, it is preferable that the water repellent treatment is to form a water repellent film made of a water repellent material on the outer surface of the protective film.
Thereby, the water-repellent treatment can be performed on the protective film relatively easily.

In the piezoelectric element of the present invention, the piezoelectric body has a layered shape, and when the thickness of the piezoelectric body is A [nm] and the thickness of the water repellent film is B [nm], B / A Is preferably 1/5000 to 1/10.
Accordingly, the water barrier property of the protective film can be further improved while preventing the water repellent film from inhibiting the displacement of the piezoelectric body.
In the piezoelectric element of the present invention, when the thickness of the water repellent film is B [nm] and the thickness of the protective film is C [nm], B / C is 1/100 to 1/10. It is preferable.
Accordingly, the water barrier property of the protective film can be further improved while preventing the water repellent film from inhibiting the displacement of the piezoelectric body.

In the piezoelectric element of the present invention, the piezoelectric body has a layered shape, and when the thickness of the piezoelectric body is A [nm] and the thickness of the protective film is C [nm], C / A is It is preferably 1/500 to 1/10.
Thereby, it is possible to further improve the water barrier property of the protective film while preventing the protective film from inhibiting the displacement of the piezoelectric body.

In the piezoelectric element of the present invention, the degree of water repellency by the water repellency treatment is preferably a water contact angle of 70 to 120 °.
Thereby, it can prevent more reliably moisture | moisture content, such as a chemical | medical solution used for humidity and a manufacturing process, to penetrate | invade through a defect | deletion part.
In the piezoelectric element according to the aspect of the invention, it is preferable that the water repellent treatment is performed on the entire outer surface of the protective film.
As a result, it is possible to more reliably prevent deterioration of the piezoelectric body due to moisture and also prevent deterioration of the electrode due to moisture.

The electronic device of the present invention includes the piezoelectric element of the present invention.
Thereby, an electronic device having excellent characteristics over a long period of time can be provided.
In the electronic device according to the aspect of the invention, it is preferable that the piezoelectric element is bonded to a substrate, and the protective film covers a portion of the outer surface of the piezoelectric element that is not covered with the substrate.
Thereby, the characteristics of an electronic device such as an actuator can be made excellent over a long period of time.

In the electronic device of the present invention, it is preferable that the substrate is formed by an etching process, and the protective film also has a function of protecting from a chemical solution used for the etching.
Thereby, the manufacturing process of the electronic device can be simplified and the yield can be prevented from decreasing.
An electronic apparatus according to the present invention includes the electronic device according to the present invention.
Thereby, an electronic device having excellent characteristics over a long period of time can be provided.

Hereinafter, a piezoelectric element, an electronic device, and an electronic apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
In the following description, a piezoelectric element will be described as an example of the piezoelectric element of the present invention, an inkjet head as an electronic device of the present invention, and an inkjet printer as an electronic apparatus of the present invention.

<Inkjet printer (electronic equipment)>
First, an inkjet printer will be described as an example of the electronic apparatus of the present invention, that is, an electronic apparatus including the electronic device of the present invention.
FIG. 1 is a schematic view showing an embodiment of an ink jet printer as an example of the electronic apparatus of the present invention. In the following description, in FIG. 1, the upper side is referred to as “upper part” and the lower side is referred to as “lower part”.

An ink jet printer 300 shown in FIG. 1 includes an apparatus main body 302, a tray 321 on which recording paper (recording medium) P is installed at the upper rear side, a paper discharge port 322 for discharging the recording paper P on the lower front side, and an upper part. An operation panel 307 is provided on the surface.
The operation panel 307 includes, for example, an organic EL display, a liquid crystal display, an LED lamp, and the like, and a display unit (not shown) that displays an error message and the like, and an operation unit (not shown) that includes various switches and the like. And.
Further, inside the apparatus main body 302, a printing apparatus (printing means) 304 mainly including a reciprocating head unit 303 and a paper feeding apparatus (paper feeding means) for feeding recording paper P to the printing apparatus 304 one by one. 305, a control unit (control unit) 306 that controls the printing device 304 and the paper feeding device 305, and a power source unit (not shown) that supplies power to each unit.

Under the control of the control unit 306, the paper feeding device 305 intermittently feeds the recording paper P one by one. The recording paper P passes near the lower part of the head unit 303. At this time, the head unit 303 reciprocates in a direction substantially perpendicular to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocating motion of the head unit 303 and the intermittent feeding of the recording paper P are the main scanning and sub-scanning in printing, and ink jet printing is performed.
The printing apparatus 304 includes a head unit 303, a carriage motor 341 that serves as a drive source for the head unit 303, and a reciprocating mechanism 342 that reciprocates the head unit 303 in response to the rotation of the carriage motor 341.

The head unit 303 has an ink jet head 1 which is an electronic device of the present invention, an ink cartridge 331 for supplying ink to the ink jet head 1, and a carriage 332 on which the ink jet head 1 and the ink cartridge 331 are mounted at the lower part thereof. ing.
Note that full-color printing is possible by using an ink cartridge 331 that is filled with ink of four colors, yellow, cyan, magenta, and black (black). In this case, the head unit 303 is provided with the inkjet head 1 corresponding to each color.

The reciprocating mechanism 342 has a carriage guide shaft 342A supported at both ends by a frame (not shown), and a timing belt 342B extending in parallel with the carriage guide shaft 342A.
The carriage 332 is supported by the carriage guide shaft 342A so as to be reciprocally movable, and is fixed to a part of the timing belt 342B.
When the timing belt 342B travels forward and backward via a pulley (not shown) by the operation of the carriage motor 341, the head unit 303 reciprocates while being guided by the carriage guide shaft 342A. During this reciprocation, ink is appropriately discharged from the inkjet head 1 and printing on the recording paper P is performed.

The sheet feeding device 305 includes a sheet feeding motor 351 serving as a driving source thereof, and a sheet feeding roller 352 that is rotated by the operation of the sheet feeding motor 351.
The paper feed roller 352 includes a driven roller 352a and a drive roller 352b that are vertically opposed to each other with a feeding path (recording paper P) of the recording paper P interposed therebetween. The drive roller 352b is connected to the paper feed motor 351. As a result, the paper feed roller 352 can feed a large number of recording sheets P set on the tray 321 one by one toward the printing apparatus 304. Instead of the tray 321, a configuration may be adopted in which a paper feed cassette that accommodates the recording paper P can be detachably mounted.

The control unit 306 performs printing by controlling the printing device 304, the paper feeding device 305, and the like based on print data input from a host computer such as a personal computer or a digital camera.
Although not shown, the control unit 306 mainly includes a memory for storing a control program for controlling each unit, a piezoelectric element driving circuit for driving a piezoelectric element (vibration source) of the present invention, which will be described later, and a printing device 304 (carriage). A driving circuit for driving the motor 341), a driving circuit for driving the paper feeding device 305 (paper feeding motor 351), a communication circuit for obtaining print data from the host computer, and a data processing circuit for processing the print data, And a CPU that is electrically connected to each unit and performs various controls in each unit.
Further, the CPU includes, for example, environmental conditions (for example, temperature, humidity, etc.) around the ink jet head 1, ink ejection status, printing status on the recording paper (recording medium) P, supply status of the recording paper P, recording Various sensors capable of detecting the ink solvent concentration and the like in the atmosphere in the vicinity of the printing portion of the paper P are electrically connected to each other.

  In such an ink jet printer 300, first, the CPU obtains print data via a communication circuit and stores it in a memory. Next, the data processing circuit processes this print data. Next, the CPU outputs a drive signal to each drive circuit based on the processing data and detection data of various sensors. The printing device 304 and the paper feeding device 305 are operated by this drive signal. As a result, printing is performed on the recording paper P.

<Inkjet head (electronic device)>
Next, the above-described inkjet head 1 will be described in detail as an example of the electronic device of the present invention, that is, the electronic device including the piezoelectric element of the present invention.
FIG. 2 is a partial cross-sectional exploded perspective view showing the inkjet head 1, and FIG. 3 is a cross-sectional view taken along the line AA in FIG. In the following, for convenience of explanation, in FIG. 2, the upper side is “upper” or “upper”, the lower side is “lower” or “lower”, the front side of the page is “left”, and the rear side of the page is “right”. In FIG. 3, the upper side is referred to as “upper” or “upper”, the lower side as “lower” or “lower”, the left side as “left”, and the right side as “right”.

  In the inkjet head 1 shown in FIGS. 2 and 3, a nozzle substrate 3 having a plurality of nozzle holes 32 is bonded to the upper surface of the cavity substrate 2, and a plurality of nozzle substrates 3 are interposed between the cavity substrate 2 and the nozzle substrate 3. A plurality of ink discharge chambers 22 are defined so as to correspond to the nozzle holes 32. A plurality of piezoelectric elements 4 serving as ink ejection drive sources are bonded to the lower surface of the cavity substrate 2 so as to correspond to the plurality of ink ejection chambers 22.

More specifically, the cavity substrate 2 is provided with a groove for forming one shared ink chamber 21 and a plurality of ink discharge chambers 22, and the nozzle substrate 3 has one common ink chamber 21 and Grooves for forming a plurality of ink orifices 31 that communicate with the plurality of ink discharge chambers 22 are formed. The cavity substrate 2 and the nozzle substrate 3 are joined to each other, so that a common ink chamber 21, an ink orifice 31, and a plurality of ink discharge chambers 22 are defined between them. Each of the cavity substrate 2 and the nozzle substrate 3 is made of, for example, silicon as a main material.
A nozzle hole 32 is formed in the nozzle substrate 3 at a position corresponding to the tip side portion of each ink discharge chamber 22, and the nozzle hole 32 communicates with the ink discharge chamber 22.

The lower wall portion of each ink discharge chamber 22 of the cavity substrate 2 is thin and functions as a vibration plate 23 that can be elastically displaced in the out-of-plane direction, that is, in the vertical direction in FIG.
In the cavity substrate 2, an ink supply port 24 for supplying ink from the outside into the common ink chamber 21 is formed in the lower wall portion of the common ink chamber 21. Ink is supplied from an external ink tank (not shown) to the common ink chamber 21 through the ink supply port 24. The ink supplied to the common ink chamber 21 is supplied to each ink discharge chamber 22 through each ink orifice 31.

  The piezoelectric element 4 is bonded to the lower surface of each diaphragm 23 of the cavity substrate 2. That is, the plurality of piezoelectric elements 4 are bonded to the lower surface of the cavity substrate 2 so as to correspond to the plurality of diaphragms 23. Each piezoelectric element 4 is connected to a voltage application means (not shown), and is adapted to vibrate (displace) the diaphragm 23 of the cavity substrate 2 when a voltage is applied. The piezoelectric element 4 will be described in detail later.

  In the ink jet head 1 as described above, when a voltage applying unit (not shown) applies a driving voltage to the piezoelectric element 4, the vibration plate 23 is deflected and displaced to the opposite side of the nozzle substrate 3, and the volume of the ink discharge chamber 22 is increased. . Next, when the drive voltage is released, the diaphragm 23 is restored by its elastic restoring force, and the volume of the ink discharge chamber 22 is rapidly contracted. Due to the ink pressure generated at this time, a part of the ink filling the ink discharge chamber 22 is discharged as an ink droplet from the nozzle hole 32 communicating with the ink discharge chamber 22.

<Piezoelectric element>
Next, the piezoelectric element 4 (piezo element) described above will be described in detail as an example of the piezoelectric element of the present invention.
Each piezoelectric element 4 includes a piezoelectric body (piezoelectric layer) 41 composed of a piezoelectric material as a main material, and a pair of electrodes 42 and 43 that sandwich the piezoelectric body 41. The upper electrode 42 is joined to the lower surface of the diaphragm 23, and a protective film 44 is provided so as to cover the piezoelectric body 41 to which the lower electrode 43 is attached.
In such a piezoelectric element 4, the piezoelectric body 41 is driven by being displaced (deformed) by applying a voltage between the electrode 42 and the electrode 43. Thereby, the diaphragm 23 is vibrated. In such a piezoelectric element 4, the piezoelectric body 41 is interposed between the pair of electrodes 42 and 43, and constitutes a piezoelectric element.

The piezoelectric body 41 is formed so as to substantially cover the entire lower surface of the diaphragm 23. The shape and size of the piezoelectric body 41 are not limited to this as long as the diaphragm 23 can vibrate.
Examples of the piezoelectric material constituting the piezoelectric body 41 include zinc oxide, aluminum nitride, lithium tantalate, lithium niobate, potassium niobate, lead zirconate titanate (PZT), barium titanate, crystal, and various other types. Among these, one or more of these can be used in combination, and in particular, zinc oxide, aluminum nitride, lithium tantalate, lithium niobate, potassium niobate and lead zirconate titanate Those mainly comprising at least one of them are preferred. By configuring the piezoelectric body 41 with such a material, the piezoelectric element 4 can be driven at a higher frequency.

The electrode 42 is longer than the piezoelectric body 41 and can be connected to a power source (not shown) on the lower surface of the cavity substrate 2.
On the other hand, the electrode 43 is longer than the length of the piezoelectric body 41 and shorter than the length of the electrode 42. Therefore, the electrode 43 can be connected to a power source (not shown) on the electrode 42.
In addition to the piezoelectric body 41, an insulating layer 45 is interposed between the electrode 42 and the electrode 43 to prevent a short circuit therebetween.

The constituent materials of the electrodes 42 and 43 are not particularly limited as long as they have conductivity. For example, Pd, Pt, Au, Ag, W, Ta, Mo, Al, Cr, Ti, Ir, Cu Or conductive materials such as alloys containing these, conductive oxides such as ITO, FTO, ATO, SnO ₂ , carbon-based materials such as carbon black, carbon nanotubes, fullerenes, polyacetylene, polypyrrole, PEDOT (poly-ethylene dioxythiophene) Examples thereof include conductive polymer materials such as polythiophene, polyaniline, poly (p-phenylene), polyfluorene, polycarbazole, polysilane or derivatives thereof, and one or more of these are used in combination. be able to. The conductive polymer material is usually used in a state of being doped with a polymer such as iron oxide, iodine, inorganic acid, organic acid, polystyrene sulphonic acid and imparted with conductivity. Among these, as materials for the electrodes, those mainly composed of Pt, Ni, Cu, Co, Au, Pd, Ag, Cr, Ti, Ir, Al or alloys containing these are preferably used.

The protective film 44 is formed so as to cover the plurality of piezoelectric elements 4. In the present embodiment, the plurality of piezoelectric elements 4 are covered with one protective film 44.
More specifically, the protective film 44 is provided on the side opposite to the cavity substrate 2 so as to cover the piezoelectric body 41.
The protective film 44 also covers a part of the electrode 43 except for the connection portion with the power source. Thereby, deterioration of the electrode 43 can be prevented, and deterioration of the piezoelectric body 41 due to moisture can be more reliably prevented.

The protective film 44 is mainly composed of an inorganic material, has a water barrier property, and has a function of preventing deterioration of the piezoelectric body 41 due to moisture.
The inorganic material is not particularly limited as long as the protective film 44 can have a water barrier property, and various inorganic materials can be used. For example, the inorganic material includes Al, Si, Ta, Nb, Ti, Ir, Zr, Ni, Pd, Pt, Au, Ag, Cu, W, Mo, Cr, Zn, or an alloy, oxide, A nitride, an oxynitride, etc. are mentioned, Among these, it can use 1 type or in combination of 2 or more types.

  At least a part of the protective film 44 is subjected to water repellent treatment. Thereby, even if a defect portion such as a pinhole or a crack is generated in the protective film 44, it is possible to prevent moisture or moisture such as a chemical solution used in the manufacturing process from entering through the defect portion. As a result, deterioration of the characteristics of the piezoelectric body 41 due to moisture can be prevented, and the characteristics of the piezoelectric element 4 can be made excellent over a long period of time.

  In other words, even the thin protective film 44 in which a defect such as a pinhole or a crack is likely to occur can surely prevent the deterioration of the characteristics of the piezoelectric body 41 due to moisture, and have excellent characteristics of the piezoelectric element 4 over a long period of time. It can be. Such a thin protective film 44 can suppress the displacement of the piezoelectric body 41 to a minimum, so that the characteristics of the piezoelectric element 4 can be made excellent.

  In this embodiment, as described above, the piezoelectric element 4 constitutes a piezoelectric element. However, the present invention is not limited to piezoelectricity caused by moisture even when the displacement of the piezoelectric body 41 is large as in the piezoelectric element. While preventing the body 41 from being deteriorated, the thickness of the protective film 44 can be reduced, and the displacement response of the piezoelectric body 41 can be made excellent. As described above, the present invention is particularly effective when the displacement amount of the piezoelectric body 41 is large and a crack is likely to occur in the protective film 44 as in a piezo element.

The water repellent treatment is not particularly limited as long as it can impart water repellency to the outer surface of the protective film 44. For example, ions that can impart water repellency such as fluorine ions are implanted (implanted). One or a combination of two or more methods, a method of forming a water-repellent film having water repellency on the outer surface of the protective film 44, and the like can be used. This water repellent treatment will be described in detail later.
The protective film covering the piezoelectric body 41 of each piezoelectric element 4 may be formed as a separate body. Further, if the protective film is formed so as to cover at least a part of the piezoelectric body 41 of the piezoelectric element 4, the effect of the present invention can be obtained.

Here, an example (first example) of a method for manufacturing the piezoelectric element 4 (piezo element) described above will be described in detail.
(First example)
FIG. 4 is a view (longitudinal sectional view) for explaining a first example of the method for manufacturing the piezo element 4 of the present embodiment. 4 shows a cross section corresponding to the cross section taken along the line AA in FIG. In the following, for convenience of explanation, the upper side in FIG. 4 is referred to as “upper” and the lower side is referred to as “lower”.

The manufacturing method of the piezoelectric element 4 in the first example includes [1A] a step of preparing a substrate 2a for manufacturing the cavity substrate 2, a [1B] step of forming an electrode 42, and [1C] a piezoelectric body 41. Forming, [1D] forming the insulating layer 45, [1E] forming the electrode 43, [1F] forming a pre-treatment protective film for the protective film 44, [1G] Forming a protective film 44 by subjecting the protective film before treatment to a water repellent treatment. Hereinafter, each process will be described in detail.
[1A]
First, as a substrate for manufacturing the cavity substrate 2, as shown in FIG. 4A, for example, a substrate 2a made of silicon as a main material is prepared.

[1B]
Next, as shown in FIG. 4B, an electrode 42 is formed on one surface of the substrate 2a.
More specifically, after forming a conductive film on one surface of the substrate 2a, an unnecessary portion of the conductive film is removed to form the electrode 42.
As the constituent material of the conductive film, the same constituent materials as those of the electrodes 42 and 43 as described above can be used.

Examples of the method for forming the conductive film include chemical vapor deposition (CVD) such as plasma CVD, thermal CVD, and laser CVD, vacuum deposition, sputtering (low temperature sputtering), dry plating methods such as ion plating, electrolytic plating, and immersion. Examples thereof include wet plating methods such as plating and electroless plating, thermal spraying methods, sol-gel methods, MOD methods, and metal foil bonding.
When removing the unnecessary portion of the conductive film, for example, a planar photoresist corresponding to the electrode 42 is formed on the conductive film by photolithography. Then, after etching the conductive film using this photoresist as a mask, the photoresist is peeled and removed. Thereby, as shown in FIG.4 (b), the electrode 42 is formed on one surface of the board | substrate 2a.
As an etching method of this conductive film, for example, one or more of physical etching methods such as plasma etching, reactive ion etching, beam etching, and light assist etching, and chemical etching methods such as wet etching are used. Can be used in combination.

[1C]
Next, as shown in FIG. 4C, the piezoelectric body 41 is formed on the electrode 42.
As a method of forming the piezoelectric body 41, the same method as the method of forming the electrode 42 described above can be used.
[1D]
Next, as illustrated in FIG. 4D, an insulating layer 45 is formed on the electrode 42 so as to be adjacent to the piezoelectric body 41.
As a method for forming the insulating layer 45, the same method as the method for forming the electrode 42 described above can be used.

[1E]
Next, as shown in FIG. 4E, the electrode 43 is formed on the piezoelectric body 41 and the insulating layer 45.
As a method for forming the electrode 43, the same method as the method for forming the electrode 42 described above can be used.

[1F]
Next, as shown in FIG. 4F, a pre-treatment protective film 44 a for the protective film 44 is formed so as to cover the electrode 43 and the side surface of the piezoelectric body 41.
More specifically, the pre-treatment protective film 44a mainly made of an inorganic material is formed in the same manner as the method for forming the electrode 42 described above.

[1G]
Next, as shown in FIG. 4G, ions that can impart water repellency such as fluorine ions are implanted (implanted) into the pre-treatment protective film 44a to form the protective film 44. Thereby, the piezoelectric element 4 is formed. Thereafter, as shown in FIG. 4G, the common ink chamber 21 is formed on the other surface (the surface opposite to the surface on which the piezoelectric element 4 is formed) of the substrate 2a on which the piezoelectric element 4 is thus formed. The cavity substrate 2 is obtained by forming the groove 21 a for the ink discharge and the groove 22 a for the ink discharge chamber 22.

When a method of implanting (implanting) ions capable of imparting water repellency such as fluorine ions is used as the water repellent treatment applied to the pretreatment protective film 44a, specifically, the pretreatment protective film 44a mainly composed of an inorganic material. An electric field is applied while supplying a gaseous fluorine compound in a state where the substrate 2a on which is formed is set (installed) in the chamber. As a result, the gaseous fluorine compound is turned into plasma and fluorine plasma is generated. The fluorine plasma is irradiated on the outer surface of the pre-treatment protective film 44a, and is adsorbed, bonded, etc. to the outer surface of the pre-treatment protective film 44a. As a result, the vicinity of the outer surface of the pre-treatment protective film 44a is fluorinated, and the protective film 44 having water repellency at least on the outer surface (only the whole or only near the outer surface) is obtained.
According to this method, the outer surface of the pre-treatment protective film 44a can be fluorinated uniformly over the entire surface, and the protective film 44 having water repellency uniformly (without unevenness) can be obtained on the outer surface.

As the constituent material of the pretreatment protective film 44a, the same constituent material as that of the protective film 44 described above can be used.
When the thickness of the piezoelectric body 41 is A [nm] and the thickness of the protective film 44 or the protective film 44a before processing is C [nm], C / A is 1/500 to 1/10. Preferably, C / A is more preferably 1/500 to 1/20. Thereby, it is possible to make the water barrier property of the protective film 44 more excellent while preventing the protective film 44 from inhibiting the displacement of the piezoelectric body 41.

In the present embodiment, the piezoelectric body 41 is configured by one layer, but the piezoelectric body 41 may be configured by stacking a plurality of layers. In this case, the thickness of the piezoelectric body 41 refers to the total thickness of the stacked layers.
In addition, the thickness of the protective film 44 or the pre-treatment protective film 44a is preferably 10 to 150 nm, and more preferably 20 to 100 nm. Thereby, it is possible to make the water barrier property of the protective film 44 more excellent while preventing the protective film 44 from inhibiting the displacement of the piezoelectric body 41.

Further, the gaseous fluorine compound is not particularly limited. For example, tetrafluoromethane (CF ₄ ), tetrafluoroethylene (C ₂ F ₄ ), propylene hexafluoride (C ₃ F ₆ ), eight fluorine Butylene chloride (C ₄ F ₈ ), SF _{6 and the} like can be mentioned, and one or more of these can be used in combination.
Such a gaseous fluorine compound may be supplied together with an inert gas such as helium gas, argon gas, or neon gas. As a result, fluorine plasma can be generated under a relatively high pressure (for example, under atmospheric pressure), and the fluorine plasma treatment can be performed more easily.

The flow rate when supplying the gaseous fluorine compound is preferably about 10 to 500 ml / min, and more preferably about 10 to 300 ml / min.
The discharge power is preferably about 100 to 1500 W, and more preferably about 300 to 500 W.
The treatment temperature is preferably about 10 to 200 ° C, more preferably about 50 to 100 ° C.
More specifically, for example, when helium and tetrafluoromethane are used as gaseous fluorine compounds and fluorine plasma is generated by atmospheric pressure plasma, the flow rate of helium and the flow rate of tetrafluoromethane are 10 respectively. It is preferable that the discharge power is about 700 W / min.

For example, when tetrafluoride methane or SF ₆ is used as a gaseous fluorine compound and fluorine plasma is generated by vacuum plasma, the degree of vacuum is 1 to 100 Pa, and the flow rate of tetrafluoromethane or SF ₆ is It is preferable to set the discharge power to about 10 to 500 ml / min and the discharge power to about 800 to 1500 W.
By setting the flow rate, discharge power, and treatment temperature of the gaseous fluorine compound within the above ranges, water repellency can be more easily and reliably imparted to at least the vicinity of the outer surface of the protective film before treatment.

As described above, when the method of injecting ions capable of imparting water repellency to the outer surface of the pre-treatment protective film is used as the water repellent treatment, the thickness of the protective film 44 is suppressed and the pre-treatment protective film 44a is formed. Water repellent treatment can be performed. In this case, since the thickness of the protective film 44 is thin, the displacement responsiveness of the piezoelectric body 41 can be further improved.
The water repellent treatment as described above is preferably performed on the entire outer surface of the protective film 44. Thereby, the deterioration of the piezoelectric body 41 due to moisture can be prevented more reliably.
The piezoelectric element 4 can be obtained as described above.

After the piezoelectric element 4 is thus formed, the common ink chamber 21 is formed on the other surface of the substrate 2a (the surface opposite to the surface on which the piezoelectric element 4 is formed) as shown in FIG. The cavity substrate 2 is obtained by forming the groove 21 a for the ink discharge and the groove 22 a for the ink discharge chamber 22.
The method for forming the grooves 21a and 22a is not particularly limited, and for example, wet etching or dry etching can be used. When the grooves 21a and 22a are formed, the piezoelectric body 41 is covered with the water-repellent protective film 44, so that deterioration of the piezoelectric body 41 due to moisture such as a developing solution, an etching solution, and a cleaning solution is prevented during etching. can do. That is, the protective film 44 also has a function of protecting from a chemical solution such as an etching solution used for this etching. Thereby, the manufacturing process of the electronic device can be simplified and the yield can be prevented from decreasing.

The ink jet head 1 can be obtained by bonding the nozzle substrate 3 to the cavity substrate 2 thus obtained.
In the manufacturing method of the piezoelectric element 4 described above, the electrode 42, the piezoelectric body 41, the insulating layer 45, the electrode 43, and the protective film 44 are sequentially formed. By removing a part of the electrode 42, the electrode 42, the piezoelectric body 41, the insulating layer 45, the electrode 43, and the protective film 44 can be collectively formed.

Next, another example (second example) of the method for manufacturing the piezoelectric element 4 (piezo element) described above will be described in detail.
(Second example)
FIG. 5 is a diagram (longitudinal sectional view) for explaining a second example of the manufacturing method of the piezo element 4 of the present embodiment. 5 shows a cross section corresponding to the cross section taken along the line AA in FIG. In the following, for convenience of explanation, the upper side in FIG. 4 is referred to as “upper” and the lower side is referred to as “lower”.

Hereinafter, the second example of the method for manufacturing the piezoelectric element 4 will be described focusing on the differences from the first example of the method for manufacturing the piezoelectric element 4 described above, and the description of the same matters will be omitted.
The method of manufacturing the piezoelectric element 4 in the second example includes [2A] a step of preparing a substrate 2a for manufacturing the cavity substrate 2, [2B] a step of forming an electrode 42, and [2C] a piezoelectric body 41. Forming, [2D] insulating layer 45, [2E] forming electrode 43, [2F] forming a pre-treatment protective film for protective film 44, [2G] Forming a protective film 44 by subjecting the protective film before treatment to a water repellent treatment.
The second example is the same as the first example except for the step [2G]. That is, steps [2A] to [2F] in the second example are the same as steps [2A] to [2F] in the first example.

[2G]
As shown in FIG. 5G, a protective film 44 is formed by forming a water-repellent water-repellent film 44b on the outer surface of the pre-treatment protective film 44a. Thereby, the piezoelectric element 4 is formed. After that, as shown in FIG. 5G, the common ink chamber 21 is formed on the other surface (the surface opposite to the surface on which the piezoelectric element 4 is formed) of the substrate 2a on which the piezoelectric element 4 is thus formed. The cavity substrate 2 is obtained by forming the groove 21 a for the ink discharge and the groove 22 a for the ink discharge chamber 22.

  When using a method of forming a water-repellent water-repellent film 44b on the outer surface of the pre-treatment protective film 44a as the water-repellent treatment applied to the pre-treatment protective film 44a, more specifically, for example, the pre-treatment protective film 44a After the water repellent film-forming material is supplied to the outer surface, it can be formed by drying it as necessary. In this case, the water repellent film 44b may be formed so as to cover one whole surface of the substrate 2a and then remove unnecessary portions, or only a necessary portion on one surface side of the substrate 2a. Alternatively, it may be formed selectively.

  As a method for selectively supplying the water-repellent film forming material to the outer surface of the pre-treatment protective film 44a, for example, a pad or stamper impregnated with the water-repellent film-forming material may be used. Examples thereof include a method of contacting the surface and a method of discharging a water repellent film forming material onto the outer surface of the pre-treatment protective film 44a by an ink jet method, and the former method is preferably used. According to such a method, the water repellent film can be selectively formed on the outer surface of the pre-treatment protective film 44a relatively easily and reliably.

Examples of the constituent material of the water repellent film 44b include a coupling agent having a functional group exhibiting water repellency, a water repellent organic material, and the like.
As the water repellent film forming material, a solution or dispersion prepared by mixing these with a solvent or dispersion medium can be used.
As the coupling agent, for example, a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, a zirconium coupling agent, an organic phosphate coupling agent, a silyl peroxide coupling agent, or the like is used. be able to.

Examples of the functional group exhibiting water repellency include a fluoroalkyl group, an alkyl group, a vinyl group, an epoxy group, a styryl group, and a methacryloxy group.
Specific examples of the coupling agent include, for example, tridecafluoro-1,1,2,2 tetrahydrooctyltriethoxysilane, tridecafluoro-1,1,2,2 tetrahydrooctyltrimethoxysilane, and tridecafluoro-1 , 1,2,2 tetrahydrooctyltrichlorosilane, octadecyltrimethoxysilane, vinyltrimethoxysilane and the like.

  On the other hand, examples of the water repellent organic material include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), and perfluoroethylene. -Fluorine resin such as propene copolymer (FEP) and ethylene-chlorotrifluoroethylene copolymer (ECTFE).

  Examples of the solvent or dispersion medium include inorganic solvents such as nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, and ethylene carbonate, methyl ethyl ketone (MEK), acetone, diethyl ketone, and methyl. Ketone solvents such as isobutyl ketone (MIBK), methyl isopropyl ketone (MIPK), cyclohexanone, alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol (DEG), glycerin, diethyl ether, diisopropyl ether, 1, 2 -Dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme), diethylene glyco Ether solvents such as ruethyl ether (carbitol), cellosolv solvents such as methyl cellosolve, ethyl cellosolve, phenyl cellosolve, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, cyclohexane, toluene, xylene, benzene, trimethyl Aromatic hydrocarbon solvents such as benzene and tetramethylbenzene, aromatic heterocyclic solvents such as pyridine, pyrazine, furan, pyrrole, thiophene and methylpyrrolidone, N, N-dimethylformamide (DMF), N, N- Amide solvents such as dimethylacetamide (DMA), halogen compound solvents such as dichloromethane, chloroform, 1,2-dichloroethane, ester solvents such as ethyl acetate, methyl acetate, ethyl formate, dimethyl sulfoxide (DMSO), sulfolane, etc. Various organic solvents such as sulfur compound solvents, nitrile solvents such as acetonitrile, propionitrile, acrylonitrile, organic acid solvents such as formic acid, acetic acid, trichloroacetic acid, trifluoroacetic acid, or mixed solvents containing these Can be mentioned.

The concentration of the constituent material of the water-repellent film 44b in the water-repellent film forming material is preferably as follows, for example, depending on the type of constituent material.
In the case of a coupling agent, the amount is preferably about 0.01 to 0.5 wt%, more preferably about 0.1 to 0.3 wt%. Moreover, in the case of an organic material, it is preferable that it is about 0.01-0.5 wt%, and it is more preferable that it is about 0.1-0.3 wt%.

  When a solution of a coupling agent is used as the material for forming the water repellent film, when the coupling agent is applied to the outer surface of the protective film 44a before treatment by immersing in the solution of the coupling agent, the immersion time is 1 to 60 minutes. It is preferable that the liquid temperature is 20 to 60 ° C., and the concentration (when ethanol or pure water is used as a solvent) is preferably 0.1 to 10%.

Further, when drying the solution of the coupling agent applied to the outer surface of the pre-treatment protective film 44a, when using a hot plate, it is preferable that the drying temperature is 50 to 150 ° C. and the drying time is 3 to 6 minutes. When an oven is used, the drying temperature is preferably 50 to 200 ° C. (especially 100 to 200 ° C. in the case of a steam atmosphere), and the drying time is preferably 10 to 60 minutes. When lamp annealing (vacuum atmosphere) is used, the light intensity is 1 ～50W, about vacuum 100 Pa (also available in normal or _{N 2} purge) and, Pt (wavelength 257 nm) as a heat source, Au (wavelength 200 to 500 nm), preferably used Si (wavelength 200 to 1000 nm) .

As described above, when the method of forming the water repellent film 44b made of a material having water repellency on the outer surface of the pre-treatment protective film 44a is used as the water repellent treatment, the pre-treatment protective film can be relatively easily performed. 44a can be subjected to water repellent treatment.
In this case, when the thickness of the piezoelectric body 41 is A [nm] and the thickness of the pre-treatment protective film 44a is B [nm], B / A is preferably 1/500 to 1/10. B / A is more preferably 1/500 to 1/50. Thereby, the water barrier property of the protective film 44 can be further improved while preventing the water repellent film 44 b from inhibiting the displacement of the piezoelectric body 41.

Further, when the thickness of the water repellent film 44b is B [nm] and the thickness of the pre-treatment protective film 44a is C [nm], B / C is preferably 1/100 to 1/10. B / C is more preferably 1/100 to 1/10. Thereby, it is possible to make the water barrier property of the protective film 44 more excellent while preventing the protective film 44 from inhibiting the displacement of the piezoelectric body 41.
Further, the thickness of the water repellent film 44b is preferably 1 to 10 nm, and more preferably 1 to 5 nm. Thereby, the water barrier property of the protective film 44 can be further improved while preventing the water repellent film 44 b from inhibiting the displacement of the piezoelectric body 41.

The degree of water repellency by the water repellent treatment is preferably a water contact angle of 70 to 120 °, more preferably a water contact angle of 90 to 120 °. Thereby, it is possible to prevent moisture and moisture such as a chemical solution used in the manufacturing process from entering through the defect portion of the protective film 44 with more certainty.
Even in the above manner, the piezoelectric element 4 can be obtained.

After the piezoelectric element 4 is thus formed, the common ink chamber 21 is formed on the other surface of the substrate 2a (the surface opposite to the surface on which the piezoelectric element 4 is formed) as shown in FIG. The cavity substrate 2 is obtained by forming the groove 21 a for the ink discharge and the groove 22 a for the ink discharge chamber 22.
Also in this case, since the piezoelectric body 41 is covered with the water-repellent protective film 44 when the grooves 21a and 22a are formed, the piezoelectric body 41 due to moisture such as a developing solution, an etching solution, and a cleaning solution is used during the etching. Can be prevented. That is, the protective film 44 also has a function of protecting from a chemical solution such as an etching solution used for this etching. Thereby, the manufacturing process of the electronic device can be simplified and the yield can be prevented from decreasing.
The ink jet head 1 can be obtained by bonding the nozzle substrate 3 to the cavity substrate 2 thus obtained.

As described above, the piezoelectric element, the electronic device, and the electronic apparatus of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each part is an arbitrary function having the same function. It can be replaced with the configuration of In addition, any other component may be added to the present invention.
The piezoelectric element of the present invention includes a piezoelectric body mainly composed of a piezoelectric material and a pair of electrodes joined to the piezoelectric body, and applying a voltage to the pair of electrodes allows the piezoelectric body to be As long as it is configured to be displaced or deformed, it is not particularly limited and can be applied to a surface acoustic wave element as disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-312198, in addition to a piezoelectric element. .

The electronic device of the present invention is not particularly limited as long as it includes the piezoelectric element of the present invention. In addition to the inkjet head, for example, an actuator such as an optical switch or an optical attenuator driven by the piezoelectric element, or a piezoelectric The present invention can be applied to a vibrator driven by an element.
Further, the ink jet head in the above-described embodiment is not limited to the ink jet printer, and can be used for other liquid droplet ejection apparatuses. For example, other droplet discharge devices include those used for the production of protein chips and DNA chips, the production of color filters for organic EL production devices and liquid crystal display devices, and the production of wiring boards by the ink jet method.

  The electronic apparatus of the present invention is not particularly limited as long as it includes the electronic device of the present invention. In addition to an inkjet printer, for example, a personal computer (mobile personal computer), a mobile phone, a digital still camera, a television Video cameras, viewfinder type, monitor direct-view type video tape recorders, laptop personal computers, car navigation devices, pagers, electronic notebooks (including those with communication functions), electronic dictionaries, calculators, electronic game machines, word processors, Workstations, videophones, crime prevention TV monitors, electronic binoculars, POS terminals, devices with touch panels (for example, cash dispensers and ticket vending machines at financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs) Display device, Sound wave diagnostic device, endoscope display device), fish detector, various measuring instruments, instruments (for example, vehicle, aircraft, ship instruments), flight simulator, other various monitors, projection display devices such as projectors Etc. can be applied.

1 is a diagram illustrating a schematic configuration of an ink jet printer that is an example of an embodiment of an electronic apparatus according to the invention. It is a disassembled perspective view which shows the inkjet head (electronic device) with which the inkjet printer of FIG. 1 was equipped. It is the sectional view on the AA line in FIG. It is a figure for demonstrating the 1st example of the manufacturing process of the piezoelectric element shown in FIG. It is a figure for demonstrating the 2nd example of the manufacturing process of the piezoelectric element shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet head 2 ... Cavity substrate 2a ... Substrate 21 ... Common ink chamber 22 ... Ink discharge chamber 23 ... Vibration plate 24 ... Ink supply port 3 ... Nozzle substrate 300 ... Inkjet printer 302 ... Main body 303 …… Head unit 304 …… Printing device 305 …… Feeding device 306 …… Control unit (control means) 307 …… Operation panel 31 …… Ink orifice 32 …… Nozzle hole 321 …… Tray 322 …… Discharge Paper mouth 331 ... Ink cartridge 332 ... Carriage 341 ... Carriage motor 342 ... Reciprocating mechanism 342A ... Carriage guide shaft 342B ... Timing belt 351 ... Paper feed motor 352 ... Paper feed roller 352a ... Driven roller 352b …… Drive roller 4 …… Piezoelectric element 41 …… Piezoelectric body 42, 43 …… Electrode 44 …… Protective film 44a …… Pre-treatment protective film 44b …… Water-repellent film 45 …… Insulating layer

Claims (13)

A piezoelectric body mainly composed of a piezoelectric material;
A pair of electrodes joined to the piezoelectric body;
A piezoelectric element configured to displace or deform the piezoelectric body by applying a voltage to the pair of electrodes,
At least a part of the piezoelectric body provided with the electrode is covered with a protective film mainly composed of an inorganic material,
A piezoelectric element, wherein a water repellent treatment is applied to at least a part of the protective film.   The piezoelectric element according to claim 1, wherein the piezoelectric body is interposed between the pair of electrodes.   3. The piezoelectric element according to claim 1, wherein the water repellent treatment is to inject ions capable of imparting water repellency into the protective film.   3. The piezoelectric element according to claim 1, wherein the water repellent treatment is to form a water repellent film made of a water repellent material on an outer surface of the protective film.   The piezoelectric body is layered, and when the thickness of the piezoelectric body is A [nm] and the thickness of the water repellent film is B [nm], B / A is 1 / 5000-1 / The piezoelectric element according to claim 4, wherein the piezoelectric element is 10.   6. The B / C is 1/100 to 1/10 when the thickness of the water repellent film is B [nm] and the thickness of the protective film is C [nm]. Piezoelectric element.   The piezoelectric body is layered, and when the thickness of the piezoelectric body is A [nm] and the thickness of the protective film is C [nm], C / A is 1/500 to 1/10. The piezoelectric element according to any one of claims 1 to 6.   The piezoelectric element according to claim 1, wherein the degree of water repellency by the water repellency treatment is a water contact angle of 70 to 120 °.   The piezoelectric element according to claim 1, wherein the water repellent treatment is applied to the entire outer surface of the protective film.   An electronic device comprising the piezoelectric element according to claim 1.   The electronic device according to claim 10, wherein the piezoelectric element is bonded to a substrate, and the protective film covers a portion of the outer surface of the piezoelectric element that is not covered with the substrate.   The electronic device according to claim 11, wherein the substrate is formed by an etching process, and the protective film also has a function of protecting from a chemical solution used for the etching.   An electronic apparatus comprising the electronic device according to claim 10.

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