JP4250593B2 - Dielectric element, piezoelectric element, ink jet head, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a dielectric element that can be applied as a capacitor, a sensor, a transducer, an actuator, and the like, a piezoelectric body (electrostrictive body) element using the dielectric element, an inkjet head, and a manufacturing method thereof. This dielectric element is particularly suitable as a ferroelectric memory, a MEMS element, a memory head, an optical shutter, a piezoelectric body of a speaker, and the like.

While a dielectric material having a high relative dielectric constant is demanded as a capacitor, a ceramic material such as BaTiO ₃ is becoming thinner in order to reduce the size of the capacitor. However, the relative permittivity of materials such as BaTiO ₃ and Pb (Zr, Ti) O ₃ is at most about 1500 for ceramic materials, and further thinning makes it more difficult to sinter, and there is a problem of defect structure at the interface. In addition, the electronic device may have poor characteristics. In recent years, there has been a movement to use a PZT (111) oriented film having a stable remanent polarization value as a memory as a dielectric element. An example of obtaining a (111) film is described in, for example, Japanese Patent Application Laid-Open No. 2003-179278 (Patent Document 1). In this method, in order to form a (111) orientation film on a Si substrate, a YSZ (111) orientation film serving as a buffer layer is provided on the Si substrate, and SrRuO ₃ (SRO) (111) is utilized using the lattice. To obtain a PZT (111) film. However, with this method, it is necessary to form a buffer layer, and because the stress of the buffer layer affects the performance of the device, it is necessary to control the stress. In some cases, the crystallinity of the SRO (111) film cannot be formed stably. Further, since these films are all formed by epitaxial growth, there is a problem that reproducibility is often unsatisfactory. As a method for solving this problem, a uniaxially oriented film having the same orientation that can be expected to have the same characteristics or an epitaxial film layer structure having excellent reproducibility is desired.

  In recent years, research on MEMS and piezoelectric applications has expanded as a piezoelectric body, and a piezoelectric element with good characteristics in a thin film is desired. A piezoelectric element is an element that expands and contracts by sandwiching a piezoelectric layer between electrodes and applying an electric field, and can be applied to a motor, an ultrasonic motor, an actuator, or the like.

The material used in the above application field is a PZT-based material discovered about 50 years ago. The PZT-based material has a sintering temperature of 1100 ° C. or higher, and material development using a sol-gel method, a sputtering method, an MBE method, a PLD method, a CVD method, or the like is in progress in order to adapt as a thin film element. However, when applied as a thin film, there is a problem that physical breakdown or the like is likely to occur in the film or at the film interface. Therefore, attempts have been made to devise the crystal structure of the piezoelectric layer to obtain a film having a large piezoelectric constant and good pressure resistance. As an example of using an (001) alignment film by sputtering as an inkjet head, there is JP-A-8-116103 (Patent Document 2). In this method, an oriented electrode is provided on a substrate to control the crystal structure of the piezoelectric film. However, in this method, the (001) oriented Pt electrode is formed on the single crystal MgO substrate with good crystallinity. However, the single crystal MgO substrate is expensive and has a small substrate size. The application is often limited. In addition, since a deliquescent MgO (111) surface is used to form a (111) oriented piezoelectric film, improvement is still necessary from the viewpoint of stable film formation of a Pt (111) crystal film. It was happening.
JP2003-179278 JP-A-8-116103

  The present invention aims to solve the above-described problems, and a dielectric layer having a preferentially or uniaxially oriented crystal structure is provided on a general-purpose substrate for film formation for producing a dielectric layer. Is based on finding ways to

That is, the first aspect of the dielectric element according to the present invention is a dielectric element having a lower electrode layer, a dielectric layer and an upper electrode layer in this order on a substrate,
At least one of the lower electrode layer and the upper electrode layer has a first electrode layer mainly containing a metal and a second electrode layer mainly containing an oxide,
The first electrode layer, the second electrode layer, and the dielectric layer each have a preferential or uniaxial crystal structure,
The half-value width obtained by fitting the pseudo-Voit function based on the peak by X-ray diffraction measurement in the preferred orientation axis or the uniaxial orientation axis of the first electrode layer, the second electrode layer, and the dielectric layer, When f1, f2, and f3, the following general formula (1):
f3>f2> f1 ≧ 0.1 ° (1)
And f1 is not less than 0.1 ° and not more than 10 °.

  Said 1st aspect WHEREIN: It is preferable that the metal contained in said 1st electrode layer forms a face centered cubic crystal, and is (111) orientation. The second electrode layer is mainly composed of a perovskite oxide and has (111) preferred orientation or uniaxial orientation, and (101) in X-ray diffraction not in a direction perpendicular to the surface of the second electrode layer. It is preferable that the half width f2 by fitting the peak pseudo-voy function is 0.5 ° or more and 3.0 ° or less. Further, the dielectric layer has a perovskite structure and has a (111) preferential orientation or a uniaxial orientation, and by fitting a pseudovoid function of the (101) peak in X-ray diffraction not in a direction perpendicular to the surface of the dielectric layer. It is preferable that the obtained half width f3 is 1.0 ° or more and 6.0 ° or less.

A second aspect of the dielectric element according to the present invention is a dielectric element having a lower electrode layer, a dielectric layer, and an upper electrode layer in this order on a substrate,
The lower electrode layer has a (111) orientation mainly composed of a face-centered cubic metal, and a half-value width obtained by fitting a pseudo-vode function of the (111) peak in X-ray diffraction is 0.1 ° or more. A first electrode layer of 10 ° or less, a (111) orientation layer that is adjacent to the first electrode layer and contains a metal oxide as a main component, and a pseudovoid function of the (101) peak in X-ray diffraction A second electrode layer having a half width of 0.5 ° or more and 11 ° or less obtained by fitting,
The dielectric layer has a (111) orientation of a perovskite structure, and a half-value width obtained by fitting a pseudo-vode function of the (101) peak in X-ray diffraction is 1.0 ° or more and 12 ° or less. It is characterized by this. In the second aspect, it is preferable that the substrate is a Si substrate, and an SiO ₂ layer having a thickness of at least 5 nm is provided as an intermediate layer on the substrate.

  Furthermore, in the first and second aspects described above, the (111) crystal orientation of the dielectric layer is preferably 80% or more, and more preferably 99% or more.

Furthermore, a third aspect of the dielectric element according to the present invention is a dielectric element having a lower electrode layer, a dielectric layer, and an upper electrode layer in this order on a substrate,
At least one of the lower electrode layer and the upper electrode layer has a first electrode layer mainly containing a metal and a second electrode layer mainly containing an oxide,
The first electrode layer, the second electrode layer and the dielectric layer are each a single crystal layer,
When the half-value widths obtained by fitting the pseudo-Voit function based on the X-ray diffraction measurement peaks in the first electrode layer, the second electrode layer, and the dielectric layer are f1, f2, and f3, respectively. The following general formula (1):
f3>f2> f1 ≧ 0.1 ° (1)
And f1 is 0.1 ° or more and 3 ° or less.

In addition, the fourth aspect of the dielectric element according to the present invention is as follows.
A (100) single crystal film comprising Y ₂ O _{3 in an amount} of 1% by weight to 20% by weight and the balance being ZrO ₂ ;
A first electrode layer of a (111) single crystal film made of face centered cubic metal;
A second electrode layer of a (111) single crystal film made of a perovskite oxide conductive material ;
A (111) single crystal dielectric layer made of a perovskite oxide;
On the Si (100) substrate in this order.

  The dielectric element having the above configuration can be used as a piezoelectric element.

  An inkjet head according to the present invention includes a liquid path communicating with a discharge port that discharges a liquid, and a piezoelectric element that applies energy for discharging the liquid from the discharge port to the liquid in the liquid path. The piezoelectric element includes a dielectric element having the above-described configuration. An ink jet recording apparatus can be configured using this ink jet head.

A method for manufacturing a dielectric element according to the present invention is a method for manufacturing a dielectric element having the above-described configuration,
When the temperature of the substrate when forming the first electrode layer is T1, the temperature of the substrate when forming the second electrode layer is T2, and the temperature of the substrate when forming the dielectric layer is T3, Equation (2):
T2 ≧ T3> T1 (2)
It is preferable to set the temperature of the substrate so as to satisfy the above.

  According to the present invention, even when a general-purpose material substrate is used, in a dielectric element having a structure in which an oxide electrode and a dielectric layer are stacked on a face-centered cubic metal film, half of the peak by the reciprocal lattice map of each layer is obtained. It is possible to obtain a dielectric element having a specific value width. Furthermore, the film formation temperature of the dielectric layer of this element can be lowered, and a stress-relaxed layer is obtained, which eliminates the need for substrate selectivity and provides a dielectric element with good reproducibility with little difference in manufacturing characteristics. be able to. This dielectric element is suitable as a piezoelectric body for an inkjet head or as a capacitor, sensor, transducer, actuator, etc., and also as a ferroelectric memory, MEMS element, memory head, optical shutter, speaker piezoelectric body, etc. Is.

  First, the first aspect of the dielectric element of the present invention will be described. The dielectric element according to the present invention has a structure in which a lower electrode layer, a dielectric layer, and an upper electrode layer are laminated in this order on a substrate. At least one of these upper and lower electrode layers has at least a first electrode layer mainly composed of metal and a second electrode layer mainly composed of oxide. The upper and lower electrode layers and the dielectric layer independently have a preferential or uniaxial crystal structure. Further, it is obtained by fitting a pseudo-void function of peaks obtained by reciprocal lattice mapping of X-ray diffraction measurement (XRD measurement) in the preferential alignment axis or uniaxial alignment axis of the first electrode layer, the second electrode layer, and the dielectric layer. The dielectric element is characterized by satisfying the following general formula (1) and f1 being not less than 0.1 ° and not more than 10 ° when the half widths obtained are f1, f2, and f3, respectively.

f3>f2> f1 ≧ 0.1 ° (1)
By adopting the above-described configuration, the dielectric element according to the present invention eliminates the need for substrate selectivity and has a stable characteristic. In addition, when this configuration is adopted, the dielectric layer can be formed by crystal film formation at a low film formation temperature. Furthermore, when a device is formed, a material system in which stress change before and after substrate removal and dielectric layer patterning is small and there are few problems such as cracking and peeling can be provided.

  The first electrode layer has a (111) orientation with a face-centered cubic structure, and f1 is a half width obtained by fitting a pseudo-voith function of the (111) peak.

  The second electrode layer is composed mainly of perovskite oxide, and has a (111) preferred orientation or a uniaxial orientation and a half-value width by fitting of a pseudovoid function of a (101) peak not in the direction perpendicular to the plane of the second electrode layer. It is preferable that f2 is 0.5 ° or more and 11 ° or less. More preferably, it is 0.5 ° or more and 3.0 ° or less.

  The material constituting the first electrode layer may be any material as long as it is a metal material that becomes a face-centered cubic crystal, for example, Ni, Pt, Pb, Ir, Cu, Al, Ag, and γ-Fe. Etc. can be illustrated. Particularly preferred are Ni, Pt and Ir. The reason why the face-centered cubic crystal is preferred is that it adopts the (111) orientation in the natural orientation film, and the (111) orientation can be easily obtained under a wide range of film formation conditions regardless of the substructure and the electrode configuration. Because. In addition, the half width of these films must be 0.1 ° or more by fitting with a pseudo-Voit function.

  It can be seen that a second electrode layer for forming a (111) -oriented dielectric layer (dielectric film) with good characteristics can be formed on the first electrode layer having a specific half width. Invented.

  When the half width f1 of the (111) peak in the reciprocal lattice mapping of the first electrode layer is less than 0.1 °, the crystallinity of the electrode layer is good, but the substrate restraint and the stress in the film become strong, Not suitable for device development. In addition, when the half width exceeds 10 °, the crystal control of the second electrode layer placed thereon cannot be performed, and eventually the crystallinity of the dielectric layer becomes random, and the dielectric characteristics, piezoelectric characteristics It may be a poor system.

  The second electrode layer has (111) preferred orientation or uniaxial orientation, and the half-value width obtained by fitting the pseudovoid function of the (101) peak of reciprocal lattice mapping is preferably 0.5 ° or more and 11 ° or less. More preferably, it is 0.5 ° or more and 3.0 ° or less. The dielectric layer provided on the second electrode layer has a perovskite structure and has a (111) preferred orientation or a uniaxial orientation, and a half-value width obtained by fitting a pseudovoid function of the (101) peak of reciprocal lattice mapping. It is preferable that f3 is 1.0 ° or more and 12 ° or less. More preferably, it is 1.0 degree or more and 6.0 degrees or less. Here, the half width of the (101) peak is specified because it appears at a position close to the (111) peak of the metal material. Therefore, it is more accurate to represent a peak other than (111). This is because a half width is obtained and preferable. In this case, measurement is performed by measuring the (101) peak that appears in the vicinity of Ψ = 35 deg. Although the peak position varies depending on the material as appropriate, it is desirable to select and judge a peak with less overlap as described above in order to achieve more accuracy.

  When the half width is in the above range, there are few troubles in the manufacturing process, and a device having good characteristics can be obtained. A discontinuous layer or a very thin film layer may be inserted between the above-mentioned layers as long as the function of the target dielectric element can be maintained.

  In the production of the dielectric element, after providing the electrode layer A having the first and second electrode layers on the production substrate, the dielectric layer and the electrode layer B are further laminated to form a dielectric. When the structure of the element is obtained, but the production substrate is used as it is as the substrate of the dielectric element, the electrode layer A becomes the lower electrode on the substrate side, and the electrode layer B becomes the upper electrode. Alternatively, when the production substrate is deleted and the substrate is disposed on the electrode layer B side, the electrode layer B becomes the lower electrode on the element substrate side, and the electrode layer A becomes the upper electrode.

  Next, a second aspect of the dielectric element of the present invention will be described. The dielectric element according to the second aspect has a (111) orientation mainly composed of a face-centered cubic metal on a substrate, and a half-value width of a (111) peak due to fitting of a pseudo-Voit function is 0.1. (111) orientation layer mainly composed of a metal electrode adjacent to the first electrode layer with an angle of not less than 10 ° and not more than 10 °, and a (101) peak half-value width of 0.5 ° or more by fitting of a pseudo-Voit function A lower electrode layer having a second electrode layer of 11 ° or less; and a (111) orientation of a perovskite structure and a (101) peak half-value width of 1.0 to 12 ° by fitting with a pseudo-Voit function A dielectric element having a dielectric layer; an upper electrode layer in this order.

  The half width of the first electrode layer is preferably 0.3 ° or more and 3 ° or less. A preferred half width of the second electrode layer is 1.0 ° or more and 5 ° or less. The preferred half width of the dielectric layer (piezoelectric layer) is 2.0 ° or more and 6 ° or less. It is desirable that the relationship of f3> f2> f1 is established when the peak half width of each layer is f1 (first electrode layer), f2 (second electrode layer), and f3 (dielectric layer). A different layer of a thin film may exist between the first electrode layer and the second electrode layer as long as the function of the target dielectric element can be maintained. It is preferable that the relationship is adjacent to. The same applies between the second electrode layer and the dielectric layer.

As the substrate in the above _second embodiment, the element of the present invention can be stably produced without changing the manufacturing process even when the SiO ₂ layer of the oxide layer is present on the Si substrate as an intermediate layer of 5 nm or more as the anchor layer. Can be made.

  In the first and second aspects, the dielectric layer preferably has a (111) crystal orientation of 80% or more. This improves the dielectric characteristics and piezoelectric characteristics. More preferably, the (111) oriented dielectric layer has a (111) crystal orientation of 90% or more, and more preferably 99% or more.

A third aspect of the present invention is a configuration relating to a (111) single crystal dielectric element,
A dielectric element having a lower electrode layer, a dielectric layer and an upper electrode layer in this order on a substrate,
At least one of the lower electrode layer and the upper electrode layer has a first electrode layer mainly composed of metal and a second electrode layer mainly composed of oxide, the first electrode layer, Each of the second electrode layer and the dielectric layer is a single crystal layer, and is based on a peak by X-ray diffraction measurement in the first electrode layer, the second electrode layer, and the dielectric layer. When the half-value widths obtained by the fitting are f1, f2, and f3, respectively, the following general formula (1):
f3>f2> f1 ≧ 0.1 ° (1)
And f1 is not less than 0.1 ° and not more than 3 °.

Furthermore, as a fourth aspect of the present invention, Y ₂ O ₃ is contained in an amount of 1% by weight to 20% by weight, and the remainder is made of a (100) single crystal film made of ZrO ₂ and a face centered cubic metal ( 111) a first electrode layer of a single crystal film; a second electrode layer of a (111) single crystal film made of a perovskite oxide conductive material; and a (111) single crystal dielectric made of a perovskite oxide. A dielectric element having a body layer on a Si (100) substrate in this order.

  By adopting the above configuration, the above-mentioned problems can be solved and a (111) single crystal dielectric layer can be obtained with good reproducibility.

  A preferred layer structure is PZT (111) / SRO (111) / Pt (111) / YSZ (100) / Si (100).

  The degree of crystal orientation is calculated from the ratio of the peak intensity due to the main orientation of the sum of the peak intensity in each direction from θ-θ of XRD measurement. In the case of a single crystal dielectric element, only the peak due to a single orientation is observed, and it is observed from the pole figure that the in-plane orientation is also aligned.

  When the perovskite oxide electrode layer is formed directly on YSZ (100), the same applies to, for example, SRO. However, it does not become a (111) film and can easily adopt a (110) orientation. Therefore, it is necessary to interpose a face-centered cubic metal layer as in the above configuration.

  A piezoelectric element can be obtained by using the structure of the dielectric element having the above structure and using a layer having a function as a piezoelectric body for the dielectric layer.

  Hereinafter, the material for forming each layer of the dielectric element will be described.

The material for forming the first electrode layer is as described above. As a material for forming the second electrode layer, a perovskite oxide conductive material can be selected and used. Examples of the perovskite-based oxide include a compound in which La _1-x Sr _x VO ₃ is 0.23 <x ≦ 1, a compound in which Gd _1-x Sr _x VO ₃ is 0.4 <x <0.5, La _1-x Sr a compound in which 0 <x <1 in _x CoO ₃ , a compound in which 0 <x <1 in Ca _1-x Sr _x RuO ₃ , a compound in which x ≠ 0 in (Ba, Ca, Sr) TiO _3-x , SrRuO ₃ , CaRuO ₃ , BaPbO ₃ , La ₂ SrCu ₂ VO _6.2 , SrCrO ₃ , LaNiO ₃ , LaCuO ₃ , BaRuO ₃ , SrMoO ₃ , CaMoO ₃ , BaMoO ₃ , SrIrO _{3 and the} like. SrRuO ₃ , LaNiO ₃ , BaPbO ₃ , and CaRuO ₃ are preferable.

The dielectric layer or piezoelectric layer is a perovskite oxide, Pb (Zr _x Ti _1-x ) O ₃ which may contain La, Nb, Si, Ca, Sr as a dopant, preferably 0. It is a compound where 2 <x <0.8. In addition to PZT, BaTiO ₃ —SrTiO ₃ and BaTiO ₃ —BaZrO ₃ materials can be used. In particular, a dielectric layer, a piezoelectric layer, or a ferroelectric layer having a (111) plane parallel to the substrate surface.

  When the PZT (111) film is formed on the face-centered cubic (111) metal film on the YSZ film, even if the PZT film is directly formed on the PZT (111) film, the crystallinity is deteriorated. Such a problem can be solved by interposing a perovskite oxide (111) layer as in the third embodiment.

Also in this case, the film thickness of each electrode is preferably in the range described later in order to maintain single crystallinity. The Y ₂ O ₃ content in the YSZ film is preferably 1% by weight or more and 20% by weight or less from the viewpoint of single crystallinity. Further, the composition in the YSZ film is not a gradient composition, and the range of composition variation is preferably within ± 5%.

An ink jet head can be formed using a piezoelectric element utilizing the structure of the dielectric element. Since the ink jet head has the piezoelectric element having the above-described configuration, the ink jet head has a high durability and a stable performance. An example of the configuration of this inkjet head will be described with reference to FIGS. FIG. 1 is a schematic diagram of an ink jet head, where 1 is a discharge port for discharging a liquid such as ink, 2 is a communication hole (liquid channel) connecting the individual liquid chamber 3 and the discharge port 1, 4 is a common liquid chamber, and 5 is A diaphragm, 6 is a lower electrode, 7 is a piezoelectric layer, and 8 is an upper electrode. As shown in the figure, the piezoelectric layer 7 has a rectangular planar shape in the surface direction of the diaphragm 5. This shape may be an ellipse, a circle, a parallelogram, etc. in addition to a rectangle. The piezoelectric layer 7 will be described in more detail with reference to FIG. 2 is a cross-sectional view of the piezoelectric layer in FIG. 1 in the width direction (direction perpendicular to the diaphragm 5). 9 is a second electrode layer, 7 is a piezoelectric layer, 5 is a diaphragm, 6 is a first electrode layer, and 8 is an upper electrode. 12 is an individual liquid chamber, and 11 is a partition of the liquid chamber. In the figure, the second electrode layer is also patterned in the same manner as the piezoelectric layer, but may be the same as the first electrode layer 6. A mode in which an anchor layer is provided between the first electrode layer 6 and the diaphragm 5 (or the substrate) is a preferable mode. As a material used for the anchor layer, metal materials such as Ti, Cr, Pb, and Ni and oxides such as TiO ₂ are preferable. The thickness of the anchor layer is 0.5 nm to 50 nm, preferably 1 nm to 20 nm. The material constituting the anchor layer may be a laminate of the above materials. The upper electrode may also have a multilayer structure having a first electrode layer and a second electrode layer. The cross-sectional shape of the film composed of 7 and 9 is shown as a rectangle, but may be a trapezoid or an inverted trapezoid. Further, the configuration order of 8, 6 and 9 may be reversed upside down. That is, the upper electrodes 9 and 6 may be formed on the piezoelectric film in the order of 7 (piezoelectric film) / 9 (second electrode layer) / 6 (first electrode layer). The reason why the configuration is reversed in this way is due to the device manufacturing method, and even when the configuration is reversed, the effect of the present invention can be obtained in the same manner.

  The first electrode layer 6 and the second electrode layer 9 or the first electrode layer 6 serving as the lower electrode are drawn out to a portion where the piezoelectric film 7 does not exist, and the upper electrode is opposite to the lower electrode (not shown) ) And connected to the drive power supply.

As a constituent material of the diaphragm, a material capable of forming a plate-like member having a Young's modulus of 50 Gpa or more, preferably 60 Gpa or more can be used. For example, SiO ₂ , SiN, SiNO, ZrO ₂ (including a stabilizing element), Examples thereof include Si (which may include a dopant), SUS, Ti, Cr, Ni, and Al. The thickness of the diaphragm 5 can be 0.5 to 10 μm, preferably 1.0 to 6.0 μm. Moreover, the thickness of an electrode layer is 0.05-0.6 micrometer, Preferably, it can be 0.08-0.3 micrometer. When the electrode layer is composed of at least two layers of the first electrode layer and the second electrode layer, the thickness of the first electrode layer can be set to 5 nm to 450 nm, preferably 10 nm to 200 nm. . The film thickness of the second electrode layer can be 5 nm to 250 nm, preferably 10 nm to 150 nm. The width Wa (see FIG. 5) of the individual liquid chamber 12 can be set to 30 to 180 μm. The length Wb (see FIG. 5) can be set to 0.3 to 6.0 mm, although it depends on the discharged droplet amount. . The cross-sectional shape of the surface perpendicular to the opening direction of the discharge port 1 is circular or star-shaped, and the diameter is preferably 7 to 30 μm. It is preferable that the cross-sectional shape of the surface along the opening direction of the discharge port has a taper shape expanded in the direction of the communication hole 2. The length of the communication hole 2 is preferably 0.05 mm to 0.5 mm. If the length is longer than this, the droplet discharge speed may be reduced. On the other hand, if it is less than this, there is a fear that the variation in the ejection speed of the droplets ejected from each ejection port becomes large.

  An ink jet recording apparatus can be configured using the ink jet head having the above configuration.

  According to the piezoelectric element having the above-described configuration, an ink jet head having a stable ejection characteristic, a long life, and a good performance can be achieved. 8 and 9 are schematic views of an ink jet recording apparatus using the ink jet head of the present invention. FIG. 9 shows an operation mechanism part from which the outer casings 81 to 85 and 87 of FIG. 8 are removed. An automatic feeding unit 97 that automatically feeds recording paper as a recording medium into the apparatus main body, and a recording paper sent from the automatic feeding unit 97 is guided to a predetermined recording position, and from the recording position to the discharge port 98. And a transport unit 99 that guides the recording paper, a recording unit that records on the recording paper transported to the recording position, and a recovery unit 90 that performs recovery processing on the recording unit. The ink jet head of the present invention is disposed and used on a carriage 92. Although FIG. 8 shows an example of a printer, the ink jet head of the present invention may be used in a facsimile, a multifunction machine, a copying machine, or an industrial discharge apparatus.

  Next, a method for manufacturing the dielectric element having the above configuration will be described. First, a first electrode layer, a second electrode layer, and a dielectric layer are formed in this order on a manufacturing substrate. At that time, the second electrode layer and the dielectric layer are preferably formed under the heating of the production substrate. In this case, the dielectric layer is preferably a (111) -oriented dielectric layer from the viewpoint of productivity and the like. .

  FIG. 3 shows a specific example of the dielectric element manufacturing method of the present invention. This manufacturing method includes at least a step of providing the first electrode layer 22 on the substrate 21, a step of providing the second electrode layer 23, and a step of providing the dielectric layer 24. The dielectric element also has an upper electrode 26. As the substrate 21, a Si substrate, a SUS substrate, or the like is selected. The characteristics of this method are not limited to the crystallinity and crystal orientation of the substrate, and any substrate material having heat resistance up to 600 ° C. may be used. However, it is preferable to select a Si (110) substrate, a Si (100) substrate, or a SUS substrate for device formation in a later process. Selection of an invar material having a low thermal expansion coefficient as the SUS substrate is a preferred embodiment. Further, since the present invention does not use the crystal structure of the substrate, an element having the same structure can be obtained even if an oxide film is formed on the Si substrate. This does not require a substrate etching operation for removing the oxide film, and has an advantage in the manufacturing process.

  As the film formation method of the electrode layer and the dielectric layer, sputtering method, MO-CVD method, laser ablation method, sol-gel method, MBE method, etc. can be used, preferably sputtering method, MO-CVD method, sol-gel method, More preferred are the MO-CVD method and the sputtering method.

  As a method of providing the first electrode layer on the substrate 21, a method of forming a film on the substrate without heating or at low temperature is preferable. Thereby, the first electrode layer becomes a film that does not have a large stress. As described above, it is necessary to select a face-centered cubic metal material having heat resistance under heating conditions in the subsequent process as described above. It is preferable to select a film of 0.1 ° to 10 °.

  In the dielectric element manufacturing method according to the present invention, the substrate temperature at the time of forming the first electrode layer is T1, the substrate temperature at the time of forming the second electrode layer is T2, and the substrate temperature at the time of forming the dielectric layer is When T3, it is preferable that the relational expression of T2 ≧ T3> T1 is satisfied. Specifically, T1 is preferably room temperature or higher and 350 ° C or lower, and more preferably 100 ° C or higher and 350 ° C or lower. T2 is 300 ° C. or higher and 800 ° C. or lower, and T3 is preferably 450 ° C. or higher and lower than 600 ° C. When T3 is T2 or less, the device is maintained while maintaining good characteristics without incurring damage such as composition shift such as oxygen loss to the second electrode layer which is an oxide electrode when forming the dielectric layer. Can be produced.

  The second electrode layer is preferably formed by a method in which the perovskite oxide is formed under substrate heating. The heating temperature is 300 ° C. or higher and 800 ° C. or lower, and preferably 450 ° C. or higher and 620 ° C. or lower. Under these conditions, the oxide electrode layer having the half width of 0.5 ° to 11 ° can be formed. Further, the dielectric layer of the present invention can be obtained by forming a dielectric layer while heating the substrate. In particular, by forming a dielectric layer on the second electrode layer, a (111) crystalline thin film having a perovskite structure can be formed as a dielectric layer at a lower temperature. The substrate temperature is as described above. For example, film formation at around 500 ° C. is good, and substrate heating at 450 ° C. or more and 550 ° C. or less is good. In addition, by adjusting conditions such as gas pressure, a dielectric layer having a half-value width of 1.0 ° to 12 ° (more preferably 1.0 ° to 6.0 °) can be obtained. it can. As a condition other than the substrate temperature according to the MO-CVD method, it is preferable to adopt a pulse MO-CVD method in which a source gas is not supplied continuously but intermittently supplied onto the substrate.

  A dielectric element manufacturing method used as the third aspect includes a step of forming YSZ (100) on a Si (100) substrate, a step of forming a face-centered cubic metal film, and a perovskite oxide electrode. This is a manufacturing method including a step of forming a film, a step of forming a (111) dielectric layer, and a step of forming another electrode on the dielectric layer.

In the YSZ film formation, the substrate temperature is heated to about 800 ° C., and the film formation is performed to fit the lattice constant of the Si substrate to obtain an epitaxial film formation. As a manufacturing method, it is preferable to form a film by a sputtering method. In particular, it is preferable to use a substrate having a SiO ₂ layer having a thickness of 15 nm or less on a Si substrate. Since the SiO ₂ layer reacts with the Zr metal to be formed and disappears, it needs to be a thin film in the above range. Next, a face-centered cubic metal (111) film is formed on the YSZ, and a perovskite oxide electrode layer is further formed, so that the oxide electrode layer also becomes a (111) single crystal layer.

  As a method of forming the dielectric layer (111), the method described above is employed.

  The above-described dielectric element manufacturing method can be applied to an inkjet head manufacturing method using a dielectric element as a piezoelectric element, and typically includes the following two methods.

  The first method is a step of forming a first electrode layer on a substrate without heating or under heating, a step of forming a second electrode layer of conductive orientation mainly composed of a metal oxide under heating, And an (111) oriented dielectric layer forming step, an upper electrode forming step, an individual liquid chamber forming step, and a liquid ejection port forming step.

  The second method is a step of forming a first electrode layer on the first substrate without heating, a step of forming a second electrode layer of a conductive orientation mainly composed of a metal oxide under heating, And a step of forming a (111) oriented dielectric layer, a step of bonding the (111) oriented dielectric layer onto an electrode layer provided on a second substrate, a step of removing the first substrate, and forming an individual liquid chamber. An inkjet head manufacturing method including at least a process and a process of forming a liquid discharge port. The step of bonding the (111) oriented dielectric layer onto the second substrate may be a method of bonding to the second substrate with the diaphragm.

  The first manufacturing method is the same as the dielectric element manufacturing method until the step of providing the piezoelectric layer, and further includes at least a step of removing a part of the substrate 21 and a step of forming an ink discharge port. Is the method. An individual liquid chamber (3 in FIG. 1 or 12 in FIG. 2) is formed by removing a part of the substrate. The individual liquid chamber can be manufactured by wet etching, dry etching, or sand milling of the substrate. A plurality of individual liquid chambers can be formed on the substrate with a certain number of pitches. As shown in FIG. 4 illustrating the planar arrangement of the inkjet head, it is a preferred embodiment that the individual liquid chambers 12 are arranged in a staggered arrangement. In FIG. 4, 12 regions indicated by broken lines are individual liquid chambers to which pressure is applied, and 7 is a patterned piezoelectric element portion. The piezoelectric film of the piezoelectric element portion is composed of at least the dielectric layer of the present invention and the upper electrode. Reference numeral 5 denotes a diaphragm portion and a lower electrode. Unlike the diaphragm, the lower electrode may be patterned as shown in FIG. At least the electrode immediately below the dielectric layer has a laminated structure of a first electrode layer and a second electrode layer. The shape of the individual liquid chambers is shown as a parallelogram. When the substrate selectivity of the first and second aspects is not required, a Si (110) substrate is used as the substrate, and wet etching with alkali is used. In order to obtain such a shape when the individual liquid chamber is created by performing the above, it is representatively illustrated. Other than this, a rectangle may be used. In the case of the parallelogram shown in FIG. 5, the piezoelectric film is also preferably patterned into a parallelogram in order to shorten the distance between the discharge ports 1 and 1 ′. A plan view of the entire individual liquid chamber is shown in FIG. 5, and the upper electrode 26 is joined to the drive circuit using 13 regions extended from the individual liquid chamber 12. Reference numeral 14 denotes a restriction of the flow path from the common liquid chamber to the individual liquid chamber. In FIG. 5, the piezoelectric film exists up to this portion, but this need not be the case.

The ink discharge port is formed into an element by a method of bonding a substrate provided with the discharge port 1 or bonding a substrate on which the discharge port 1 and the communication hole 2 are formed. The discharge port can be formed by etching, machining, or laser beam irradiation. The substrate on which the discharge ports are formed may be the same as or different from the substrate on which the piezoelectric layer is formed. Substrates selected in different cases include SUS substrates, Ni substrates, etc., and the difference in thermal expansion coefficient from the substrate on which the piezoelectric layer is formed is 1 × 10 ⁻⁸ / ° C. to 1 × 10 ⁻⁶ / ° C. Preferably, the material is selected.

  As a method for bonding the substrates, a method using an organic adhesive may be used, but a method using metal bonding with an inorganic material is preferable. The materials used for metal bonding are In, Au, Cu, Ni, Pb, Ti, Cr, Pd, etc., which can be bonded at a low temperature of 300 ° C. or less, and the difference in thermal expansion coefficient from the substrate is small. In addition to avoiding problems due to warping of elements when scaled, there is no damage to the piezoelectric layer, which is preferable.

Next, the second manufacturing method will be described. The second manufacturing method is a method of transferring a piezoelectric layer (dielectric layer) provided on the first substrate to the second substrate. Until the piezoelectric layer is provided, the method is the same as that shown in FIG. 3, but the diaphragm 5 is formed on the upper electrode without patterning the piezoelectric layer and transferred to the second substrate. Alternatively, an electrode and / or a diaphragm is formed on the piezoelectric layer, the diaphragm is bonded to the second substrate, and transfer is performed including the piezoelectric layer. In the second substrate, for example, the individual liquid chamber 12, the communication hole 2, and the common liquid chamber 4 are formed by steps a to e shown in FIG. Step a is a mask formation step corresponding to the individual liquid chamber on the second substrate, step b is a step processed by etching or the like from the top (the hatched portion means the processing portion), and step c is the mask removal and communication hole 2 The mask creation process for the above, d is a communication hole and common liquid chamber forming process by processing of the hatched portion by etching or the like, e is a schematic view of the state where the individual liquid chamber, the communication hole, and the common liquid chamber are formed by removing the mask It was shown to. f indicates a state in which the discharge port and the substrate on which a part of the common liquid chamber is formed are joined. It is preferable that the substrate surface 16 with the discharge port is subjected to water repellent treatment.
The state of e or f in FIG. 6 is used for the second substrate to be bonded to the piezoelectric layer of the first substrate. When there is no diaphragm on the piezoelectric layer, a second substrate provided with a diaphragm on the individual liquid chamber 12 in the state e or f of FIG. 6 is used. FIG. 7 shows a state where the first substrate is removed and the piezoelectric layer is patterned after bonding. The stacking order of the electrodes from the diaphragm 5 side of the upper electrode 8 in FIG. 7 is the order of the second electrode layer and the first electrode layer.

  In addition, as described as an alternative to the latter method, a piezoelectric body in which a diaphragm is formed on a second substrate, a piezoelectric layer is transferred thereon, and the first substrate is removed The layer may or may not be patterned. When this step is taken, it is preferable to use the metal bonding layer as the lower electrode.

  As a feature of the manufacturing method of the ink jet head of the present invention, the manufacturing process includes patterning of the piezoelectric layer and / or the first substrate removal process. At this time, the first electrode layer made of metal is used. It can be used as an etching stop layer and is preferable in terms of the process. Further, when the half width is in the above range, there is an advantage that there is little change in stress before and after removing the substrate and before and after patterning of the piezoelectric layer, and there are few problems such as cracking, peeling and warping. Furthermore, this means that it is easy to deal with a large-area substrate, and the cost per device can be reduced and the manufacturing throughput can be improved. In addition, there is a similar effect at the time of patterning the piezoelectric layer, and an element with little characteristic change from the film forming process can be obtained, which is very advantageous.

  Next, the present invention will be described with reference to examples.

Example 1
As a first electrode layer, Pt was formed by sputtering at a substrate temperature of 300 ° C. to a thickness of 100 nm on a Si substrate on which a SiO ₂ layer of a thermal oxide film was formed with a thickness of 100 nm. Further, SrRuO ₃ (SRO) was formed to a thickness of 15 nm at a substrate temperature of 600 ° C. by pulse MO-CVD. Further, a dielectric layer made of Pb (Zr, Ti) O ₃ was similarly deposited on the SRO at a substrate temperature of 500 ° C. and 290 nm by a pulse MO-CVD method so that the Zr / Ti ratio was 47/53. The crystal orientation of each film by XRD measurement of this element is (111) orientation is 99% or more parallel to the substrate surface, and the half width by fitting of the pseudo-Voit function is as shown in FIGS. The half width f3 of the dielectric layer is 3.9 °, the half width f2 of the second electrode layer is 1.7 °, and the half width f1 of the first electrode layer is 0.46 °. It was. As described above, the dielectric layer and the second electrode layer were measured using the (101) peak.
An SRO film having a thickness of 100 nm was formed thereon as an upper electrode to obtain a dielectric element of the present invention. As a result of electrical measurement, the remanent polarization value 2Pr was 47 μC / cm ² and the coercive electric field Ec was 71 kV / cm, showing good characteristics, and sufficient results for a ferroelectric memory were obtained.

(Example 2)
Next, an example of the piezoelectric body of the present invention will be described.

A SiN layer was sputtered to a thickness of 1.5 μm on a 200 μm thick Si (110) substrate. On top of this, Ti is 5 nm thick as an anchor layer, Ir electrode is 50 nm thick, and the substrate temperature is 200 ° C. by rf-sputtering. Further, the second electrode layer of SRO is formed at the substrate temperature 600 ° C. by the same method. The film was formed with a thickness of 100 nm. Further, Pb (Zr, Ti) O ₃ having a Zr / Ti ratio of 48/52 was formed as a piezoelectric layer at 2.5 μm. On top of this, Pt / Cr was formed as an upper electrode, a plurality of piezoelectric layers were patterned with a width of 45 μm and a length of 3 mm, and the Si substrate was partially removed by wet etching to separate individual liquids with a width of 58 μm and a length of 2.2 mm. A chamber was formed. A piezoelectric body having a cross-sectional shape shown in FIG. 2 was obtained for one patterning. Here, a device having a pitch of 84 μm for each discharge port was formed. During this production, the first electrode layer functioned well as an etch stop layer. When a displacement of 20 V was applied to this element and the amount of displacement was measured, a good value of 0.15 μm was measured.
The structure of this piezoelectric body is that all layers of PZT / SRO / Ir have a (111) orientation of 99%, and the half width was measured in the same manner as in Example 1, and f1 = 0.53 ° and f2 = 2. 0.1 °, f3 = 4.5 °.

  The SUS substrate shown in FIG. 10 provided with the communication hole 2, the discharge port 1, and the ink supply path was joined to this element to obtain the ink jet head of the present invention.

  From this element, ejection of droplets was confirmed with good characteristics by driving at a voltage of 20V. Moreover, it was a thing with few characteristic differences in every some discharge outlet. Moreover, the characteristic difference between devices was also small.

(Example 3)
Next, as an ink jet head manufacturing method, an example using steps different from those in Example 2 will be described.

A second electrode layer of LaNiO ₃ (60 nm thickness) is laminated on the first electrode layer of Pt (100 nm thickness) (deposition at a substrate temperature of 250 ° C.) on a Si (100) substrate, and Zr / Pb (Zr, Ti) O ₃ having a Ti ratio of 50/50 was formed to a thickness of 3.0 μm. The substrate temperature during film formation was as follows: T1 was room temperature, T2 was 650 ° C., and T3 was 520 ° C. A Pt / Ti electrode having a film thickness of 200 nm was formed on the piezoelectric layer, and a SiN layer serving as a vibration plate was formed thereon with a thickness of 2.0 μm. This substrate was bonded to a second Si substrate processed in the state of e) in FIG. 6 at 150 ° C. via an Au layer. After bonding, the Si (100) substrate was removed by etching with alkali. Thereafter, the first and second electrode layers were patterned by ICP, and the piezoelectric layer was patterned by a mixed acid etchant, leaving the piezoelectric layer on the individual liquid chamber. This was joined to a SUS plate having a 20 [mu] m [Phi] discharge opening, thereby obtaining an ink jet head of the present invention. The ejection characteristics were evaluated, and the same results as in Example 2 were obtained.

  The orientation of each film at this time was 99% for (111), and the half widths f1, f2, and f3 were 0.56 °, 2.0 °, and 3.3 °. In addition, when the first substrate was a Si (110) substrate, an element whose characteristics were not significantly changed was obtained.

(Example 4 and Comparative Example 1)
Forming a TiO ₂ layer on the Si substrate SiO ₂ layers with 20 nm, was formed of Pt (111) at 70nm thick at the substrate temperature of 200 ° C.. On top of this, ferroelectric characteristics were evaluated when a PZT (111) film (Zr / Ti = 40/60) was directly formed and when a PZT film was formed through a 40 nm thickness of an SRO (111) layer. . Both PZT films were formed by pulse MO-CVD at a substrate temperature of 500 ° C. and a thickness of 300 nm. Further, the SRO film was formed while heating the substrate at 600 ° C. In the case of the present invention having SRO, the remanent polarization value 2Pr was 44 μC / cm ² , whereas in the case without the SRO layer, it was 21 μC / cm ² . The half widths f1, f2, and f3 at this time were 0.63 °, 2.9 °, and 4.4 °, respectively.

(Comparative Example 2)
A (111) film was formed by sputtering Pt (100 nm thickness) on a MgO (111) single crystal substrate at a substrate temperature of 600 ° C. An SRO layer (15 nm thickness) was placed on this at 650 ° C., and a PZT film having a Zr / Ti ratio of 48/52 was formed at 600 ° C. by sputtering. The half widths of these layers were 0.09 °, 0.48 °, and 1.5 ° for f1, f2, and f3, respectively. Although the half width of PZT was relatively large, there was a portion where peeling occurred after bonding to the second substrate in the same process as in Example 3, and there was a need for improvement. Further, when no PbTiO ₃ layer was interposed between Pt and PZT, the variation in crystallinity of PZT was large.

(Example 5 and Comparative Example 3)
After cleaning the Si (100) substrate and removing the oxide film on the surface, an oxide film was formed by H ₂ O ₂ treatment, and a Zr layer was formed by sputtering with a metal target. The substrate heating temperature was 800 ° C. After depositing Zr, a YSZ layer was deposited in a target containing 30% Y component. The YSZ layer was a (100) -oriented single crystal epitaxial film.

  The total film thickness of the two layers was set to 30 to 60 nm, and the Pt layer was formed to 50 to 80 nm at 600 ° C. with substrate heating. The half width f1 of the Pt layer was 0.10 °. An SRO layer was formed thereon at 600 ° C. to a thickness of 150 nm. Both the Pt layer and the SRO layer were (111) single crystal layers. When a PZT film was formed thereon, a (111) single crystal layer could be obtained. At this time, f2 and f3 were 0.4 ° and 1.5 °, respectively. For comparison, when a PZT film was formed on a Pt (111) layer without an SRO layer, it did not become a single crystal layer, but a film with a random orientation in the in-plane direction, and ( 110) The film also contained the component.

  Further, even when the single crystal property was deteriorated to a half-value width f1 measured from the Pt (111) single crystal layer up to 3.0 °, the single crystal layer could be formed up to the dielectric layer. When the crystallinity exceeds 1, the single crystallinity disappears, and not only the uniaxial orientation but other orientation peaks are observed.

It is the schematic of an inkjet head. It is sectional drawing of a piezoelectric material element. It is the schematic which shows the manufacturing process of the dielectric material concerning this invention. It is a top view of an inkjet head. It is a top view of the separate liquid chamber of an inkjet head. It is the schematic which shows the 2nd board | substrate manufacturing process of an inkjet head. It is sectional drawing of the long direction of an inkjet head. It is a general-view figure of an inkjet recording device. It is the schematic of the inkjet recording device except the exterior. It is board | substrate sectional drawing which has a communicating hole and a discharge outlet. It is a graph which shows half value width data (the result of having performed pseudo Voith function fitting by the peak of a reciprocal lattice map). It is a graph which shows half value width data (the result of having performed pseudo Voith function fitting by the peak of a reciprocal lattice map). It is a graph which shows half value width data (the result of having performed pseudo Voith function fitting by the peak of a reciprocal lattice map).

Explanation of symbols

1: liquid discharge port 2: communication hole 3: individual liquid chamber 4: common liquid chamber 7: piezoelectric layer 12: individual liquid chamber 13: upper electrode 21: substrate 22: first electrode layer 23: second electrode layer 24: Dielectric layer

Claims (13)

A dielectric element having a lower electrode layer, a dielectric layer and an upper electrode layer in this order on a substrate,
At least one of the lower electrode layer and the upper electrode layer has a first electrode layer mainly containing a metal and a second electrode layer mainly containing an oxide,
The first electrode layer, the second electrode layer, and the dielectric layer each have a preferential or uniaxial crystal structure,
The half widths obtained by fitting the pseudo-Voit function based on the X-ray diffraction measurement peaks in the preferential orientation axis or the uniaxial orientation axis of the first electrode layer, the second electrode layer, and the dielectric layer, respectively. , F1, f2, and f3, the following general formula (1):
f3>f2> f1 ≧ 0.1 ° (1)
And f1 is not less than 0.1 ° and not more than 10 °.   The dielectric element according to claim 1, wherein the metal contained in the first electrode layer forms a face-centered cubic crystal and has a (111) orientation.   The second electrode layer is mainly composed of perovskite oxide and has (111) preferred orientation or uniaxial orientation, and the (101) peak in X-ray diffraction that is not in the direction perpendicular to the surface of the second electrode layer. 3. The dielectric element according to claim 1, wherein a half-value width f <b> 2 by fitting of a pseudo-Voit function is 0.5 ° to 3.0 °.   The dielectric layer has a perovskite structure, is (111) preferred orientation or uniaxial orientation, and is obtained by fitting a pseudovoid function of the (101) peak in X-ray diffraction that is not in a direction perpendicular to the plane of the dielectric layer. The dielectric element according to any one of claims 1 to 3, wherein the half width f3 is not less than 1.0 ° and not more than 6.0 °. A dielectric element having a lower electrode layer, a dielectric layer and an upper electrode layer in this order on a substrate,
The lower electrode layer has a (111) orientation mainly composed of a face-centered cubic metal, and a half-value width obtained by fitting a pseudo-vode function of the (111) peak in X-ray diffraction is 0.1 ° or more. A first electrode layer of 10 ° or less, a (111) orientation layer that is adjacent to the first electrode layer and contains a metal oxide as a main component, and a pseudovoid function of the (101) peak in X-ray diffraction A second electrode layer having a half width of 0.5 ° or more and 11 ° or less obtained by fitting,
The dielectric layer has a (111) orientation of a perovskite structure, and a half-value width obtained by fitting a pseudo-vode function of the (101) peak in X-ray diffraction is 1.0 ° or more and 12 ° or less. A dielectric element characterized by the above. The dielectric element according to claim 5, wherein the substrate is a Si substrate, and an SiO ₂ layer having a thickness of at least 5 nm is provided on the substrate as an intermediate layer.   The dielectric element according to claim 1, wherein the dielectric layer has a (111) crystal orientation degree of 80% or more.   The dielectric element according to claim 7, wherein the (111) crystal orientation degree of the dielectric layer is 99% or more. A dielectric element having a lower electrode layer, a dielectric layer and an upper electrode layer in this order on a substrate,
At least one of the lower electrode layer and the upper electrode layer has a first electrode layer mainly containing a metal and a second electrode layer mainly containing an oxide,
The first electrode layer, the second electrode layer and the dielectric layer are each a single crystal layer,
When the half-value widths obtained by fitting the pseudo-Voit function based on the X-ray diffraction measurement peaks in the first electrode layer, the second electrode layer, and the dielectric layer are f1, f2, and f3, respectively. The following general formula (1):
f3>f2> f1 ≧ 0.1 ° (1)
And f1 is not less than 0.1 ° and not more than 3 °. A (100) single crystal film comprising Y ₂ O _{3 in an amount} of 1% by weight to 20% by weight and the balance being ZrO ₂ ;
A first electrode layer of a (111) single crystal film made of face centered cubic metal;
A second electrode layer of a (111) single crystal film made of a perovskite oxide conductive material ;
A (111) single crystal dielectric layer made of a perovskite oxide;
On the Si (100) substrate in this order.
  A piezoelectric element comprising the dielectric element according to claim 1.   An ink jet head comprising: a liquid path communicating with a discharge port that discharges a liquid; and a piezoelectric element that imparts energy for discharging the liquid from the discharge port to the liquid in the liquid path. An inkjet head, which is the piezoelectric element according to 11. A method for manufacturing a dielectric element according to any one of claims 1 to 10,
When the temperature of the substrate when forming the first electrode layer is T1, the temperature of the substrate when forming the second electrode layer is T2, and the temperature of the substrate when forming the dielectric layer is T3, A method for manufacturing a dielectric element satisfying the formula (2).
T2 ≧ T3> T1 (2)

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