JP5270278B2 - Method for manufacturing piezoelectric element - Google Patents

Description

  The present invention relates to a piezoelectric element including a piezoelectric film having a predetermined pattern, a manufacturing method thereof, and a liquid discharge apparatus including the piezoelectric element.

  An actuator in which a piezoelectric element including a piezoelectric film having piezoelectricity that expands and contracts as the electric field application intensity increases and decreases and an electrode that applies an electric field to the piezoelectric film in a predetermined direction is mounted on an ink jet recording head Etc. are used. As a piezoelectric material, a composite oxide having a perovskite structure such as lead zirconate titanate (PZT) is known. The piezoelectric film is not a continuous film, but is formed by a pattern composed of a plurality of convex portions mechanically separated from each other, so that expansion and contraction occur smoothly and a larger displacement amount is obtained.

  The piezoelectric film is formed with a thickness of about 1 to 5 μm, for example, in order to obtain a desired strain displacement. This thickness is thicker than a nanometer-order electrode (for example, a thickness of 200 nm). As described in Patent Document 1 and the like, conventionally, a piezoelectric film is generally patterned by dry etching.

  Dry etching is known as anisotropic etching. However, PZT or the like is a material that is difficult to be etched, and is thicker than an electrode of the order of nm, so that dry etching of the piezoelectric film is more difficult than an electrode or the like. Therefore, even if the piezoelectric film is dry-etched, it does not become completely anisotropic etching, and the side surface of the formed convex portion tends to be tapered.

  In the ink jet recording head, the uniformity of the piezoelectric characteristics of the plurality of convex portions forming the piezoelectric film has been demanded at a higher level for higher image quality. However, in dry etching with a tapered side surface, it is difficult to adjust the angle of the side surfaces of the multiple convex portions with high accuracy, and in the future, variations in the piezoelectric characteristics due to variations in the shape of the convex portions will affect the image quality. There is a possibility that it cannot be ignored. Considering the accuracy of the side surface shape of the convex portion, it is preferable that the side surface shape of the convex portion is stably a substantially vertical shape.

  A piezoelectric film such as PZT has a problem that it takes time for patterning because dry etching is difficult due to material characteristics and thickness as described above. Also, since dry etching requires a vacuum process, the apparatus is expensive and the manufacturing cost is high.

As a dielectric film patterning method,
A mask method for forming a dielectric film having a predetermined pattern by performing vapor deposition in a state where a mask having a predetermined pattern is in close contact with the substrate (Patent Document 2, etc.),
And, by forming a dielectric film on the substrate on which the resist pattern is formed, and then removing the resist pattern, the dielectric film portion located on the resist pattern is removed together with the resist pattern, and the dielectric film is patterned. A lift-off method (Patent Documents 3 and 4) is known.
Special Table 2003-532289 JP-A-9-125228 Japanese Unexamined Patent Publication No. 2000-164575 Japanese Unexamined Patent Publication No. 2005-3737

  In the mask method, the energy of the vapor deposition particles tends to change around the mask shielding part, and the film quality at the pattern edge part may change. This tendency is particularly remarkable in the case of multi-element oxides.

  Since the lift-off method forms a film on a substrate on which a resist pattern is formed, it cannot be applied to film formation at a temperature higher than the heat resistance temperature of the resist. Therefore, it cannot be applied to film formation of PZT or the like that requires a film formation temperature of about 500 to 600 ° C.

  It is conceivable to perform lift-off using a sacrificial layer having a higher heat resistance temperature instead of the resist pattern. However, even if the lift-off method is directly applied to patterning of a thick piezoelectric film of the order of μm, the thickness of the piezoelectric film is large, and it is difficult to remove the sacrificial layer and unnecessary portions of the piezoelectric film located thereon. In addition, the unnecessary portions of the piezoelectric film connected to each other are peeled off to remove the unnecessary portions, so that the smoothness of the side surfaces of the convex portions tends to be poor, pattern defects may occur, and the shape accuracy is good. It is difficult to get a good pattern.

  Patterning by selective growth overcomes the above-mentioned drawbacks, but a good film and a fragile film grow at the same time in the film forming chamber, which may cause contamination by the fragile film.

The present invention has been made in view of the above circumstances, and can easily pattern a piezoelectric film at a low cost without requiring an expensive apparatus, and has good shape accuracy of the pattern of the piezoelectric film. An object of the present invention is to provide a novel patterning technique for a piezoelectric film that does not have the problem of contamination.
An object of the present invention is to provide a method of manufacturing a piezoelectric element using the patterning technique and a piezoelectric element manufactured by the manufacturing method.

In the piezoelectric element manufacturing method of the present invention, a lower electrode, a piezoelectric film having a predetermined pattern composed of one or a plurality of convex portions, and an upper electrode are sequentially formed on a substrate, and the lower electrode and the upper electrode are In the method of manufacturing a piezoelectric element that is driven by applying an electric field therebetween,
Forming a non-patterned solid piezoelectric film on the substrate on which the lower electrode is formed (A);
A step (B) of forming a removal electrode for removing an unnecessary portion of the solid piezoelectric film having a pattern corresponding to the unnecessary portion of the solid piezoelectric film on the solid piezoelectric film;
Applying an electric field between the lower electrode and the removal electrode to generate a crack in unnecessary portions of the removal electrode and the solid piezoelectric film (C);
And (D) removing unnecessary portions of the removal electrode and the solid piezoelectric film.

In the step (B), it is preferable to form the upper electrode having a pattern corresponding to the piezoelectric film having the predetermined pattern at the same time as the removing electrode and being non-conductive with the removing electrode.
After the step (D), it may be configured to further include a step (E) of forming the upper electrode having a pattern corresponding to the piezoelectric film having the predetermined pattern.

In the step (A), it is preferable to form a columnar structure film composed of a number of columnar bodies extending in a non-parallel direction with respect to the substrate surface of the substrate as the solid piezoelectric film.
In the step (A), it is preferable to form a zone I columnar structure film in the Thornton zone model as the solid piezoelectric film.
The piezoelectric film made of a columnar structure film may have a crystal structure or an amorphous structure, but preferably has a crystal structure.

In the step (A), it is preferable to form the solid piezoelectric film having a surface roughness Ra ≧ 200 mm.
In this specification, the “surface roughness Ra” is measured by scanning a range of 2 μm × 2 μm in the tapping mode by AFM.
In the step (A), the solid piezoelectric film is preferably formed by a vapor phase method.

In the first piezoelectric element of the present invention, a lower electrode, a piezoelectric film having a predetermined pattern including one or a plurality of convex portions, and an upper electrode are sequentially formed on a substrate, and the lower electrode and the upper electrode In a piezoelectric element that is driven with an electric field applied between,
Forming a non-patterned solid piezoelectric film on the substrate on which the lower electrode is formed (A);
A step (B) of forming a removal electrode for removing an unnecessary portion of the solid piezoelectric film having a pattern corresponding to the unnecessary portion of the solid piezoelectric film on the solid piezoelectric film;
Applying an electric field between the lower electrode and the removal electrode to generate a crack in unnecessary portions of the removal electrode and the solid piezoelectric film (C);
It is manufactured by the manufacturing method which has the process (D) which removes the unnecessary part of the said electrode for removal and the said solid piezoelectric material film, It is characterized by the above-mentioned.

In the first piezoelectric element of the present invention, it is preferable that the piezoelectric film is a columnar structure film including a large number of columnar bodies extending in a non-parallel direction with respect to the substrate surface of the substrate.
In the first piezoelectric element of the present invention, the piezoelectric film is preferably a zone I columnar structure film in a Thornton zone model.
In the first piezoelectric element of the present invention, it is preferable that the piezoelectric film has a surface roughness Ra ≧ 200 mm.

In the second piezoelectric element of the present invention, a lower electrode, a piezoelectric film having a predetermined pattern including one or a plurality of convex portions, and an upper electrode are sequentially formed on a substrate, and the lower electrode and the upper electrode In a piezoelectric element that is driven with an electric field applied between,
The piezoelectric film is a zone I columnar structure film in a Thornton zone model.

In the first and second piezoelectric elements of the present invention, it is preferable that the piezoelectric film is mainly composed of one or more perovskite oxides represented by the following general formula (P).
General formula ABO ₃ (P)
(A: Element of A site, including at least one element selected from the group consisting of Pb, Ba, Sr, Bi, Li, Na, Ca, Cd, Mg, K, and lanthanide elements.
B: Element of B site, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Mg, Sc, Co, Cu, In, Sn, Ga, Zn, Cd, Fe, Ni, Hf , And at least one element selected from the group consisting of Al.
O: oxygen.
The molar ratio of the A site element, the B site element, and the oxygen element is 1: 1: 3 as a standard, but these molar ratios may deviate from the reference molar ratio within a range where a perovskite structure can be taken. )
In the present specification, “main component” is defined as a component of 80 mol% or more.

  A liquid ejection apparatus of the present invention includes the first or second piezoelectric element of the present invention and a liquid ejection member provided adjacent to the piezoelectric element, and the liquid ejection member stores liquid. And a liquid discharge port through which the liquid is discharged from the liquid storage chamber in response to application of the electric field to the piezoelectric film.

According to the present invention, a piezoelectric film can be easily patterned at low cost without requiring an expensive apparatus, the shape accuracy of the pattern of the piezoelectric film is good, and there is no problem of contamination during film formation. It is possible to provide a patterning technique for a piezoelectric film.
According to the present invention, it is possible to provide a method for manufacturing a piezoelectric element using the patterning technique and a piezoelectric element manufactured by the manufacturing method.

"Piezoelectric element, inkjet recording head"
With reference to the drawings, a piezoelectric element according to an embodiment of the present invention and the structure of an ink jet recording head (liquid ejecting apparatus) including the piezoelectric element will be described. FIG. 1 is a sectional view (a sectional view in the thickness direction of a piezoelectric element) of an ink jet recording head. In order to facilitate visual recognition, the scale of the constituent elements is appropriately changed from the actual one.

  The piezoelectric element 1 of the present embodiment is an element in which a lower electrode 20, a piezoelectric film 30, and an upper electrode 40 are sequentially laminated on a substrate 10, and is manufactured by the method for manufacturing a piezoelectric element of the present invention. is there. The piezoelectric element 1 is driven by applying an electric field in the thickness direction to the piezoelectric film 30 by the lower electrode 20 and the upper electrode 40.

  In the present embodiment, a piezoelectric film 30 composed of a plurality of convex portions 31 mechanically separated from each other is formed. More specifically, the lower electrode 20 is formed on substantially the entire surface of the substrate 10, and a piezoelectric film 30 having a pattern in which line-shaped convex portions 31 are arranged in a stripe shape is formed on the lower electrode 20. An upper electrode 40 is formed on the substrate. The pattern of the piezoelectric film 30 such as the shape, the number, and the pitch of the convex portions 31 forming the piezoelectric film 30 is not limited to that shown in the figure, and is appropriately designed. For example, the piezoelectric film 30 may be composed of a single convex portion 31.

The substrate 10 is not particularly limited, and examples thereof include substrates such as silicon, glass, stainless steel (SUS), yttrium stabilized zirconia (YSZ), alumina, sapphire, SiC, and SrTiO ₃ . As the base material 10, a laminated substrate such as an SOI substrate in which a SiO ₂ film and a Si active layer are sequentially laminated on a silicon substrate may be used.

The composition of the lower electrode 20 is not particularly limited, and examples thereof include metals such as Au, Pt, Ir, IrO ₂ , RuO ₂ , LaNiO ₃ , and SrRuO ₃ , and combinations thereof. The composition of the upper electrode 40 is not particularly limited, and examples thereof include materials exemplified for the lower electrode 20, electrode materials generally used in semiconductor processes such as Al, Ta, Cr, and Cu, and combinations thereof. The thickness of the lower electrode 20 and the upper electrode 40 is not particularly limited and is preferably 50 to 500 nm.

The composition of the piezoelectric film 30 is not particularly limited, and it is preferable that the main component is one or more perovskite oxides represented by the following general formula (P).
General formula ABO ₃ (P)
(A: Element of A site, including at least one element selected from the group consisting of Pb, Ba, Sr, Bi, Li, Na, Ca, Cd, Mg, K, and lanthanide elements.
B: Element of B site, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Mg, Sc, Co, Cu, In, Sn, Ga, Zn, Cd, Fe, Ni, Hf , And at least one element selected from the group consisting of Al.
O: oxygen.
The molar ratio of the A site element, the B site element, and the oxygen element is 1: 1: 3 as a standard, but these molar ratios may deviate from the reference molar ratio within a range where a perovskite structure can be taken. )

As the perovskite oxide represented by the general formula (P),
Lead titanate, lead zirconate titanate (PZT), lead zirconate, lead lanthanum titanate, lead lanthanum zirconate titanate, lead zirconium niobate titanate titanate, lead niobium zirconium titanate titanate, titanium titanate zinc niobate Lead-containing compounds such as lead acid, and mixed crystal systems thereof;
Examples thereof include lead-free compounds such as barium titanate, barium strontium titanate, bismuth sodium titanate, bismuth potassium titanate, sodium niobate, potassium niobate, lithium niobate, and mixed crystal systems thereof.

  Since the electrical characteristics become better, the perovskite oxide represented by the general formula (P) is composed of Mg, Ca, Sr, Ba, Bi, Nb, Ta, W, and Ln (= lanthanide element (La , Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)).

  The film thickness of the piezoelectric film 30 is not particularly limited, and is usually 1 μm or more, for example, 1 to 5 μm. This thickness is larger than that of the electrodes 20 and 40 in the order of nm (preferably 50 to 500 nm).

  In this embodiment, since the piezoelectric film 30 is easily patterned and the pattern shape accuracy is good, the piezoelectric film 30 is a columnar structure film composed of a number of columnar bodies extending in a non-parallel direction with respect to the substrate surface of the substrate 10. (Refer to a cross-sectional SEM photograph in FIG. 6A). In the piezoelectric film 30 formed of a columnar structure film, a large number of columnar bodies exposed on the side surface 31S of the convex portion 31 have a structure that is cleanly cut at the interface of the columnar bodies. The piezoelectric film 30 preferably has crystallinity because the piezoelectric film 30 made of a columnar structure film can be easily formed. The piezoelectric film 30 may have an amorphous structure as long as the piezoelectric film 30 made of a columnar structure film can be formed.

The average column diameter of many columnar bodies forming the piezoelectric film 30 is not particularly limited, and is preferably 30 nm to 1 μm. If the average column diameter of the columnar body is too small, there is a possibility that sufficient crystal growth as a piezoelectric body does not occur, or desired piezoelectric performance cannot be obtained. If the average column diameter of the columnar body is excessive, the shape accuracy after patterning may decrease.
In this specification, “average column diameter of columnar bodies” is determined by observing a cross-sectional SEM image and calculating the average value of the column diameters of a total of 10 columnar bodies selected at random.

  With regard to the columnar structure film, studies have been made on the relationship between the substrate temperature and film formation pressure during film formation and the shape and column diameter of the generated columnar body, and the classification of the columnar body. Such studies are described in detail in Movchan and Demchishin, Phys. Met. Mettlelogr., 28, 83 (1969) for deposited films and Thonton, J. Vac. Sci. Technol., 11, 666 (1974) for sputtered films. Are described in detail.

The columnar structure film of zone T of the Thornton zone model is a fibrous dense film in which grain growth is suppressed (see the surface SEM photograph in FIG. 9B). The columnar structure film of zone I of the Thornton zone model is a film in which grain growth is promoted and there are many gaps between grains (see the surface SEM photograph in FIG. 6B).
Conventionally, a dense film in which grain growth is suppressed is considered good, and a zone I columnar structure film has not been actively used. Unlike conventional common sense, in the present embodiment, the piezoelectric film 30 is preferably a zone I columnar structure film in the Thornton zone model.

  The surface roughness Ra of the piezoelectric film 30 is not particularly limited. Grain growth leads to deterioration of the surface roughness Ra. That is, the zone I columnar structure film in the Thornton zone model in which the grain growth is promoted has a larger surface roughness Ra than the zone T columnar structure film. Conventionally, a piezoelectric film is preferably dense and has high surface smoothness. Unlike the conventional common sense, in this embodiment, it is preferable that the surface roughness Ra ≧ 200 mm of the piezoelectric film 30 (see Table 1).

  It is preferable that the side surface 31S of the convex portion 31 of the piezoelectric film 30 is substantially perpendicular to or close to the substrate surface of the substrate 10. Specifically, the angle θ of the side surface 31S of the convex portion 31 of the piezoelectric film 30 with respect to the substrate surface of the substrate 10 is not particularly limited, and is 90 ± 30 ° considering the pattern shape accuracy of the side surface 31S of the convex portion 31. It is preferably within the range, and particularly preferably within the range of 90 ± 10 °. In the manufacturing method of the present invention, the angle θ of the side surface 31S of the convex portion 31 can be stably within the above range.

  In the piezoelectric actuator 2, a vibration plate 50 that vibrates due to expansion and contraction of the piezoelectric film 30 is attached to the back surface of the substrate 10 of the piezoelectric element 1. The piezoelectric actuator 2 is also provided with control means (not shown) such as a drive circuit for controlling the driving of the piezoelectric element 1.

  The ink jet recording head (liquid ejecting apparatus) 3 generally includes an ink chamber (liquid storing chamber) 61 in which ink is stored on the back surface of the piezoelectric actuator 2 and an ink discharging port (in which ink is discharged from the ink chamber 61 to the outside). An ink nozzle (liquid storage and discharge member) 60 having a liquid discharge port 62 is attached. In the ink jet recording head 3, the electric field strength applied to the piezoelectric element 1 is increased / decreased to expand / contract the piezoelectric element 1, thereby controlling the ejection of ink from the ink chamber 61 and the ejection amount.

Instead of attaching the vibration plate 50 and the ink nozzle 60 which are members independent of the substrate 10, a part of the substrate 10 may be processed into the vibration plate 50 and the ink nozzle 60. For example, when the substrate 10 is made of a laminated substrate such as an SOI substrate, the substrate 10 is etched from the back side to form the ink chamber 61, and the vibration plate 50 and the ink nozzle 60 are formed by processing the substrate itself. Can do.
The piezoelectric element 1 and the ink jet recording head 3 of the present embodiment are configured as described above.

"Production method"
With reference to FIG. 2, the manufacturing method of the piezoelectric element 1 and the ink jet recording head 3 will be described. FIG. 2 is a process diagram and is a cross-sectional view corresponding to FIG.

(Process (A))
First, as shown in FIG. 2A, the lower electrode 20 is formed on the substantially entire surface of the substrate 10 by a known vapor phase method or the like, and the unpatterned solid piezoelectric film 30P is formed on the substrate. . The method for forming the solid piezoelectric film 30P is not particularly limited, and gas phase methods such as sputtering, MOCVD, plasma CVD, PLD (pulse laser deposition), and discharge plasma sintering; sol-gel method and organometallic Liquid phase methods such as decomposition methods; and aerosol deposition methods. The thickness of the piezoelectric film 30 is usually 1 μm or more, for example, 1 to 5 μm.

  As the solid piezoelectric film 30 </ b> P, it is preferable to form a columnar structure film including a large number of columnar bodies extending in a non-parallel direction with respect to the substrate surface of the substrate 10. In the present embodiment, it is particularly preferable to form a solid piezoelectric film 30P made of a zone I columnar structure film in the Thornton zone model and having a surface roughness Ra ≧ 200 mm.

  The average column diameter of many columnar bodies forming the solid piezoelectric film 30P is not particularly limited, and is preferably 30 nm to 1 μm. If the average column diameter of the columnar body is too small, there is a possibility that sufficient crystal growth as a piezoelectric body does not occur, or desired piezoelectric performance cannot be obtained. If the average column diameter of the columnar body is excessive, the shape accuracy after patterning may decrease.

The growth direction of the columnar body is not particularly limited, and is preferably substantially perpendicular to the substrate surface of the substrate 10 or close to it. Specifically, the growth direction of the columnar body with respect to the substrate surface of the substrate 10 is preferably within a range of 90 ± 30 °, and particularly preferably within a range of 90 ± 10 °.
It is preferable to form a solid piezoelectric film 30P having crystal orientation. For example, a solid piezoelectric film 30P having crystal orientation in the (100) direction can be formed.

Since the columnar structure film can be easily formed, the solid piezoelectric film 30P can be formed by sputtering, MOCVD, plasma CVD, PLD (pulse laser deposition), discharge plasma sintering, or the like. A gas phase method is preferred.
A columnar body having a desired average column diameter can be grown in a desired direction by adjusting the film formation conditions such as the substrate temperature, the film formation pressure, and the plasma conditions according to the composition. The film formation temperature is set to a temperature at which a solid piezoelectric film 30P composed of a large number of columnar bodies can be stably formed. For example, PZT and a part of the A site and / or B site of PZT are made of other elements. In the substituted PZT system, 500 to 600 ° C. is preferable.

(Process (B))
Next, as shown in FIG. 2B, the upper electrode 40 having a pattern corresponding to the piezoelectric film 30 having a predetermined pattern and the unnecessary portion 30N of the solid piezoelectric film 30P are formed on the solid piezoelectric film 30P. A removal electrode 41 having a pattern and for removing the unnecessary portion 30N of the solid piezoelectric film 30P is formed.

  In this step, it is necessary to provide a gap between the upper electrode 40 and the removal electrode 41 so that the upper electrode 40 and the removal electrode 41 are not conductive. This method of forming the upper electrode 40 simultaneously with the removing electrode 41 is preferable because the number of steps can be reduced as compared to the method described later shown in FIG.

  The film formation method of the upper electrode 40 and the removal electrode 41 is not particularly limited, and a known gas phase method is preferable. The composition of the removal electrode 41 is not particularly limited, and the same composition as that of the upper electrode 40 can be used. The removal electrode 41 may have the same composition as the upper electrode 40 or a different composition. It is preferable that the upper electrode 40 and the removal electrode 41 have the same composition, which can be formed simultaneously.

(Process (C))
Next, as shown in FIG. 2 (c), an electric field is not applied between the lower electrode 20 and the upper electrode 40, but an electric field is selectively applied between the lower electrode 20 and the removal electrode 41 to remove it. Cracks are generated in the electrode 41 and the unnecessary portion 30N of the solid piezoelectric film 30P (see FIG. 7B). For example, an electric field can be selectively applied between the lower electrode 20 and the removal electrode 41 by bringing the probe 42 into contact only with the removal electrode 41.
By applying an electric field between the lower electrode 20 and the removal electrode 41, the unnecessary portion 30N of the solid piezoelectric film 30P expands and contracts, and stress is applied to the unnecessary portion 30N of the solid piezoelectric film 30P and the removal electrode 41 located thereon. It is considered that cracks are generated.

  The present inventor has found that cracks are likely to occur in a solid piezoelectric film 30P made of a zone I columnar structure film in the Thornton zone model and having a surface roughness Ra ≧ 200 mm. The columnar structure film of zone I in the Thornton zone model is a film structure in which the grain growth is promoted and there are many gaps between grains (see the surface SEM photograph in FIG. 6B). It is considered that cracks that reach the surface of the lower electrode 20 from the base point are likely to occur. The columnar structure film of zone T in the Thornton zone model has a dense film structure with no gap between grains and good adhesion between grains (refer to the surface SEM photograph in FIG. 9B), so an electric field is applied. However, it is thought that cracks are difficult to enter.

  The voltage applied between the lower electrode 20 and the removal electrode 41 is not particularly limited as long as it is a level that can generate a crack in the removal electrode 41 and the unnecessary portion 30N of the solid piezoelectric film 30P. For example, for a piezoelectric film having a thickness of 3 to 4 μm, the drive voltage is usually about 20 to 30V. The inventor is composed of a zone I columnar structure film in the Thornton zone model, and in the case of a solid piezoelectric film 30P having a surface roughness Ra ≧ 200 mm, for example, about 40 to 60 V with respect to a solid piezoelectric film having a thickness of 3 to 4 μm. It has been confirmed that a crack is generated in the unnecessary portion 30N of the removal electrode 41 and the solid piezoelectric film 30P by applying a voltage (see Examples 1 to 3 below).

(Process (D))
Next, as shown in FIG. 2D, the removal electrode 41 and the unnecessary portion 30N of the solid piezoelectric film 30P are removed. Since cracks are formed in the unnecessary portion 30N of the removal electrode 41 and the solid piezoelectric film 30P, the unnecessary portion 30N of the removal electrode 41 and the solid piezoelectric film 30P can be selectively removed easily. After this step, a piezoelectric film 30 having a predetermined pattern composed of a plurality of convex portions 31 is formed.

  An example of the removing method is wet etching. Since the etchant easily penetrates into the cracks of the removal electrode 41 and the unnecessary portion 30N of the solid piezoelectric film 30P, the removal electrode 41 and the unnecessary portion 30N of the solid piezoelectric film 30P are easily and selectively selected by wet etching. Can be removed. Examples of other removal methods include ultrasonic cleaning and peeling using an adhesive tape. The removal of the unnecessary portion 30N of the solid piezoelectric film 30P can be performed in a short time regardless of the thickness of the solid piezoelectric film 30P.

  In the present embodiment, it has been described that it is preferable to form the solid piezoelectric film 30P made of a columnar structure film. Since adjacent columnar bodies are easily mechanically separated from each other, when the unnecessary portion 30N of the solid piezoelectric film 30P made of a columnar structure film is removed, it can be satisfactorily separated at the interface of the columnar bodies. Therefore, many columnar bodies exposed on the side surface 31S of the convex portion of the piezoelectric film 30 are cut off cleanly at the interface of the columnar body, and the side surface 31S of the convex portion has good smoothness.

  It has been described that the growth direction of the columnar body forming the solid piezoelectric film 30 is preferably substantially perpendicular to or close to the substrate surface of the substrate 10. Specifically, it has been described that the growth direction of the columnar body with respect to the substrate surface of the substrate 10 is preferably within a range of 90 ± 30 °, and particularly preferably within a range of 90 ± 10 °.

  If the growth direction of the columnar body is within such a range, the side surface 31S of the convex portion 31 of the piezoelectric film 30 can be made substantially perpendicular to or close to the substrate surface of the substrate 10. Specifically, the angle θ of the side surface 31S of the convex portion 31 of the piezoelectric film 30 is stably within a range of 90 ± 30 ° with respect to the substrate surface of the substrate 10, and preferably within a range of 90 ± 10 °. can do.

  The piezoelectric element 1 is manufactured as described above. The ink jet recording head 3 is manufactured by attaching the diaphragm 50 and the ink storing and discharging member 60 to the piezoelectric element 1 (not shown).

  As shown in FIGS. 3A to 3E, only the removal electrode 41 is formed without forming the upper electrode 40 in the step (B) (FIG. 3B), and the steps (C) and ( After performing D) (FIGS. 3C and 3D), the step (E) of forming the upper electrode 40 (FIG. 3E) may be performed.

  As described above, according to the present embodiment, the piezoelectric film 30 can be easily patterned at low cost without requiring an expensive apparatus such as dry etching. According to this embodiment, the shape accuracy of the pattern of the piezoelectric film 30 is good, and the piezoelectric film 30 can be patterned without the problem of contamination during film formation as in selective growth.

"Inkjet recording device"
With reference to FIG. 4 and FIG. 5, a configuration example of an ink jet recording apparatus including the ink jet recording head 3 of the above embodiment will be described. 4 is an overall view of the apparatus, and FIG. 5 is a partial top view.

The illustrated ink jet recording apparatus 100 includes a printing unit 102 having a plurality of ink jet recording heads (hereinafter simply referred to as “heads”) 3K, 3C, 3M, and 3Y provided for each ink color, and each head 3K, An ink storage / loading unit 114 that stores ink to be supplied to 3C, 3M, and 3Y, a paper feeding unit 118 that supplies recording paper 116, a decurling unit 120 that removes curling of the recording paper 116, and a printing unit An adsorption belt conveyance unit 122 that conveys the recording paper 116 while maintaining the flatness of the recording paper 116, and a print detection unit that reads a printing result by the printing unit 102. 124 and a paper discharge unit 126 that discharges printed recording paper (printed matter) to the outside.
Each of the heads 3K, 3C, 3M, and 3Y forming the printing unit 102 is the ink jet recording head 3 of the above embodiment.

In the decurling unit 120, heat is applied to the recording paper 116 by the heating drum 130 in the direction opposite to the curl direction, and the decurling process is performed.
In the apparatus using roll paper, as shown in FIG. 4, a cutter 128 is provided at the subsequent stage of the decurling unit 120, and the roll paper is cut into a desired size by this cutter. The cutter 128 includes a fixed blade 128A having a length equal to or larger than the conveyance path width of the recording paper 116, and a round blade 128B that moves along the fixed blade 128A. The fixed blade 128A is provided on the back side of the print. The round blade 128B is arranged on the print surface side with the conveyance path interposed therebetween. In an apparatus using cut paper, the cutter 128 is unnecessary.

  The decurled and cut recording paper 116 is sent to the suction belt conveyance unit 122. The suction belt conveyance unit 122 has a structure in which an endless belt 133 is wound between rollers 131 and 132, and at least portions facing the nozzle surface of the printing unit 102 and the sensor surface of the printing detection unit 124 are horizontal ( Flat surface).

  The belt 133 has a width that is wider than the width of the recording paper 116, and a plurality of suction holes (not shown) are formed on the belt surface. An adsorption chamber 134 is provided at a position facing the nozzle surface of the printing unit 102 and the sensor surface of the print detection unit 124 inside the belt 133 that is stretched between the rollers 131 and 132. The recording paper 116 on the belt 133 is sucked and held by suctioning at 135 to make a negative pressure.

When the power of a motor (not shown) is transmitted to at least one of the rollers 131 and 132 around which the belt 133 is wound, the belt 133 is driven in the clockwise direction in FIG. 4 and is held on the belt 133. The recording paper 116 is conveyed from left to right in FIG.
Since ink adheres to the belt 133 when a borderless print or the like is printed, the belt cleaning unit 136 is provided at a predetermined position outside the belt 133 (an appropriate position other than the print region).

  A heating fan 140 is provided on the upstream side of the printing unit 102 on the paper conveyance path formed by the suction belt conveyance unit 122. The heating fan 140 heats the recording paper 116 by blowing heated air onto the recording paper 116 before printing. Heating the recording paper 116 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 102 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) perpendicular to the paper feed direction (see FIG. 5). Each of the print heads 3K, 3C, 3M, and 3Y is a line-type head in which a plurality of ink discharge ports (nozzles) are arranged over a length exceeding at least one side of the maximum-size recording paper 116 targeted by the ink jet recording apparatus 100. It is configured.

  Heads 3K, 3C, 3M, and 3Y corresponding to the respective color inks are arranged in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 116. ing. A color image is recorded on the recording paper 116 by ejecting the color ink from each of the heads 3K, 3C, 3M, 3Y while conveying the recording paper 116.

The print detection unit 124 includes a line sensor that images the droplet ejection result of the print unit 102 and detects ejection defects such as nozzle clogging from the droplet ejection image read by the line sensor.
A post-drying unit 142 including a heating fan or the like for drying the printed image surface is provided at the subsequent stage of the print detection unit 124. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  A heating / pressurizing unit 144 is provided downstream of the post-drying unit 142 in order to control the glossiness of the image surface. The heating / pressurizing unit 144 presses the image surface with a pressure roller 145 having a predetermined surface irregularity shape while heating the image surface, and transfers the irregular shape to the image surface.

  The printed matter obtained in this manner is outputted from the paper output unit 126. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. In the ink jet recording apparatus 100, there is provided sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 126A and 126B. It has been.

When the main image and the test print are simultaneously printed on a large sheet of paper, the cutter 148 may be provided to separate the test print portion.
The ink jet recording apparatus 100 is configured as described above.

(Design changes)
The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate without departing from the spirit of the present invention.

  Examples and comparative examples according to the present invention will be described.

Example 1
A 10 nm thick Ti film and a 150 nm thick Ir lower electrode were sequentially formed on a Si substrate by sputtering under the condition of a substrate temperature of 350 ° C. A solid PZT film (solid piezoelectric film) having a thickness of 2 μm was formed on the obtained substrate by sputtering. The film forming conditions were as follows.
Sputtering device: Rf sputtering device,
Target composition: Pb _1.3 (Zr _0.52 Ti _0.48 ) O ₃ ,
Substrate temperature: 550 ° C.
Deposition pressure: 1.0 Pa
Deposition power density: 4.3 W / cm ²
Deposition gas: Ar / O ₂ = 100/1 (molar ratio).

When the XRF analysis of the obtained solid PZT film was conducted, the composition was Pb _1.1 (Zr _0.52 Ti _0.48 ) O ₃ .
When the XRD analysis of the obtained solid PZT film was carried out, it was a (100) oriented film having a perovskite structure. The XRD pattern is shown in FIG.

  A cross-sectional SEM photograph and a surface SEM photograph of the obtained solid PZT film are shown in FIGS. 6 (a) and 6 (b), respectively. As shown in FIG. 6A, the obtained solid PZT film is a columnar structure film composed of a number of columnar bodies extending in a direction substantially perpendicular to the substrate surface, and the average column diameter is 0.3 μm. It was. As shown in FIG. 6B, the obtained solid PZT film was composed of a large number of grains, and gaps were observed between the grains. Each grain is composed of a large number of columnar bodies, and the grains themselves are structures extending in a direction substantially perpendicular to the substrate surface. The obtained solid PZT film was a zone I columnar structure film in the Thornton zone model. When the surface roughness Ra of the solid PZT film was determined by AFM, it was 200 mm.

  On the solid PZT film, a resist pattern “AZ9245” manufactured by Clariant Co., Ltd. was used to form a resist pattern of a reverse pattern of an electrode for removal described later with a thickness of 10 μm. A Pt / Ti film (Pt: 150 nm thickness / Ti: 50 nm thickness) was deposited on the resist pattern. Thereafter, this substrate was immersed in acetone, and the portion located on the resist pattern and the resist pattern of the Pt / Ti film was removed by a lift-off method. As described above, a Pt / Ti removal electrode having a dot pattern composed of a plurality of 200 μmφ dots and a plurality of 100 μmφ dots was formed.

Next, a probe was brought into contact with each removal electrode, and a voltage of 60 V was applied between the lower electrode and all the removal electrodes. When the surface was observed with an optical microscope, cracks were found in all the removal electrodes. When the adhesive tape is peeled off on the electrode for removal, only the portion located under the electrode for removal and the removal electrode of the solid PZT film is selectively peeled off, and the PZT piezoelectric body having a reverse pattern of the removal electrode A membrane was obtained.
FIG. 7A shows optical micrographs after applying an electric field between the lower electrode and the removing electrode, after applying an electric field between the lower electrode and the removing electrode, and after tape peeling, respectively. -Shown in FIG.

When a perspective SEM image of the PZT film after patterning was observed, the side surfaces of the convex portions were substantially perpendicular to the substrate surface, and the pattern shape accuracy was good. In addition, a large number of columnar bodies exposed on the side surfaces of the convex portions were cut cleanly at the interface of the columnar bodies, and the side surfaces of the convex portions had good smoothness. A perspective SEM photograph is shown in FIG.
Finally, a Pt / Ti upper electrode (Pt: 150 nm thickness / Ti: 50 nm thickness) was deposited on the PZT film to obtain the piezoelectric element of the present invention.

(Examples 2 and 3)
A piezoelectric element of the present invention was obtained in the same manner as in Example 1 except that the substrate temperature and the film forming pressure when forming the solid PZT film were set to the conditions shown in Table 1.
When XRD analysis was performed in the same manner as in Example 1, the obtained solid PZT films were all (100) oriented films having a perovskite structure. The XRD pattern is shown in FIG.
When SEM observation was carried out in the same manner as in Example 1, the obtained solid PZT film was a zone I columnar structure film in the Thornton zone model, and the obtained solid PZT film was composed of a number of grains, and between the grains. A gap was seen. Table 1 shows the surface roughness Ra of the solid PZT film.

  In any example, the PZT film could be patterned in the same manner as in Example 1. When a cross-sectional SEM image of the PZT film after patterning was observed, the side surfaces of the convex portions were in a direction substantially perpendicular to the substrate surface in each example as in Example 1, and the pattern shape accuracy was good. It was. In addition, a large number of columnar bodies exposed on the side surfaces of the convex portions were cut cleanly at the interface of the columnar bodies, and the side surfaces of the convex portions had good smoothness.

(Comparative Examples 1 and 2)
A solid PZT film having a thickness of 3.3 μm was formed in the same manner as in Example 1 except that the substrate temperature and the film formation pressure when forming the solid PZT film were changed to the conditions shown in Table 1.
When XRD analysis was performed in the same manner as in Example 1, the obtained solid PZT films were all (100) oriented films having a perovskite structure. The XRD pattern is shown in FIG.
A cross-sectional SEM photograph and a surface SEM photograph of the obtained solid PZT film are shown in FIGS. 9A and 9B, respectively. The obtained solid PZT film was a columnar structure film composed of a number of columnar bodies extending in a direction substantially perpendicular to the substrate surface, and the average column diameter was 0.3 μm.

  In the obtained solid PZT film, grain growth was suppressed, and a large number of grains were observed. However, there was no gap between grains and the film structure was good with good adhesion between grains. The obtained solid PZT film was a columnar structure film of zone T in the Thornton zone model. Table 1 shows the surface roughness Ra of the solid PZT film. Since the grain growth is suppressed in Comparative Examples 1 and 2, the surface roughness Ra is smaller than in Examples 1 to 3.

  When a removal electrode was formed in the same manner as in Example 1 and a voltage of 80 V was applied between the lower electrode and the removal electrode, cracks were found only in the vicinity of the outer periphery of the removal electrode. When the tape was peeled in the same manner as in Example 1, the portion located under the removal electrode and the removal electrode of the solid PZT film could not be peeled off at all, and the PZT film could not be patterned.

  The piezoelectric element and the manufacturing method thereof according to the present invention are mounted on an ink jet recording head, a magnetic recording / reproducing head, a MEMS (Micro Electro-Mechanical Systems) device, a micro pump, an ultrasonic probe, an ultrasonic motor, and the like. The present invention is preferably applicable to ferroelectric elements such as piezoelectric actuators and ferroelectric memories.

Sectional drawing which shows the structure of the piezoelectric element of the embodiment which concerns on this invention, and an inkjet recording head (A)-(d) is process drawing which shows the manufacturing method of the piezoelectric element of embodiment which concerns on this invention. (A)-(e) is process drawing which shows the other manufacturing method of the piezoelectric element of embodiment which concerns on this invention. 1 is a diagram illustrating a configuration example of an ink jet recording apparatus including the ink jet recording head of FIG. Partial top view of the ink jet recording apparatus of FIG. (A) is a cross-sectional SEM photograph of the solid PZT film of Example 1, and (b) is a surface SEM photograph of the solid PZT film of Example 1. (A) is an optical micrograph before applying an electric field between the lower electrode and the removal electrode in Example 1, and (b) is an electric field applied between the lower electrode and the removal electrode in Example 1. Later optical micrograph, (c) is an optical micrograph after tape peeling in Example 1 Perspective SEM photograph after patterning in Example 1 (A) is a cross-sectional SEM photograph of the solid PZT film of Comparative Example 1, and (b) is a surface SEM photograph of the solid PZT film of Comparative Example 1. XRD patterns of Examples 1 and 2 and Comparative Examples 1 to 3

Explanation of symbols

1 Piezoelectric element 3, 3K, 3C, 3M, 3Y Inkjet recording head (liquid ejection device)
DESCRIPTION OF SYMBOLS 10 Substrate 20 Lower electrode 30 Piezoelectric film 30P Solid piezoelectric film 30N Unnecessary portion of solid piezoelectric film 31 Convex part 31S Side surface of convex part 40 Upper electrode 41 Removal electrode 60 Ink nozzle (liquid storage and discharge member)
61 Ink chamber (liquid storage chamber)
62 Ink ejection port (liquid ejection port)

Claims (3)

A lower electrode, a piezoelectric film having a predetermined pattern consisting of one or a plurality of convex portions, and an upper electrode are sequentially formed on the substrate, and an electric field is applied between the lower electrode and the upper electrode to be driven. In the manufacturing method of the piezoelectric element,
Forming a non-patterned solid piezoelectric film on the substrate on which the lower electrode is formed (A);
A step (B) of forming a removal electrode for removing an unnecessary portion of the solid piezoelectric film having a pattern corresponding to the unnecessary portion of the solid piezoelectric film on the solid piezoelectric film;
Applying an electric field between the lower electrode and the removal electrode to generate a crack in unnecessary portions of the removal electrode and the solid piezoelectric film (C);
It possesses a step (D) of removing the unnecessary portion of the removed electrode and the solid piezoelectric film,
In the step (A), the solid piezoelectric film is a zone I columnar structure film in the Thornton zone model, which is composed of a number of columnar bodies extending in a non-parallel direction to the substrate surface of the substrate. A method of manufacturing a piezoelectric element, characterized in that a PZT film satisfying 420Å ≧ Ra ≧ 200Å is formed by a vapor phase method.   In the step (B), the upper electrode which has a pattern corresponding to the piezoelectric film having the predetermined pattern at the same time as the removal electrode and is non-conductive with the removal electrode is formed. The method for manufacturing a piezoelectric element according to claim 1.   The method for manufacturing a piezoelectric element according to claim 1, further comprising a step (E) of forming the upper electrode having a pattern corresponding to the piezoelectric film having the predetermined pattern after the step (D). .