JP2012094613A - Piezoelectric element, droplet jet head, droplet jet device, and method of manufacturing piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element that complicates the formation of a continuous leakage path on side surfaces of a piezoelectric layer.SOLUTION: The piezoelectric element includes a first electrode 20, a piezoelectric layer 30 formed on the first electrode 20, and a second electrode 40 formed on the piezoelectric layer 30. Side surfaces of the piezoelectric layer 30 have a first wavy surface 32 provided with a plurality of first grooves 35 extending in the direction of the second electrode 40 from the first electrode 20, a second wavy surface 33 disposed nearer to the second electrode 40 than the first wavy surface 32 and provided with a plurality of second grooves 36 extending in the direction of the second electrode 40 from the first electrode 20, and a boundary region 34 between the first wavy surface 32 and the second wavy surface 33. First intervals of the first grooves 35 are different from second intervals of the second grooves 36.

Description

  The present invention relates to a piezoelectric element, a droplet ejecting head, a droplet ejecting apparatus, and a method for manufacturing a piezoelectric element.

  In order to reduce the thickness of piezoelectric elements and enable high-speed driving, piezoelectric actuators and ink jet recording heads that can be manufactured using thin film technology are known. For example, Patent Document 1 describes an ink jet recording head that can be manufactured using thin film technology.

  In the ink jet recording head described in Patent Document 1, there is a possibility that a leak path is generated between the upper electrode and the lower electrode through the side surface of the piezoelectric layer of the piezoelectric element.

  Therefore, a piezoelectric element in which a leak path hardly occurs on the side surface of the piezoelectric layer is expected.

Japanese Patent Laid-Open No. 10-226071

  According to some aspects of the present invention, a piezoelectric element in which a leak path hardly occurs on the side surface of the piezoelectric layer, a manufacturing method thereof, and a droplet ejecting head and a droplet ejecting apparatus including the piezoelectric element are provided. can do.

(1) A piezoelectric element which is one aspect of the present invention is:
A first electrode;
A piezoelectric layer formed on the first electrode;
A second electrode formed on the piezoelectric layer;
Including
The side surface of the piezoelectric layer includes a first wavy surface in which a plurality of first grooves extending in a direction from the first electrode toward the second electrode are formed, and the first wavy surface than the first wavy surface. A second wavy surface provided on the two-electrode side and formed with a plurality of second grooves extending in a direction from the first electrode toward the second electrode; the first wavy surface; The boundary area with the wavy surface;
Have
The first interval of the first groove is different from the second interval of the second groove.

  In the present invention, the word “upper” is used as, for example, “to form another specific thing (hereinafter referred to as“ B ”) on“ above ”of a specific thing (hereinafter referred to as“ A ”)”. . In the present invention, in the case of this example, the case where B is formed directly on A and the case where B is formed on A via another are included. Is used. Similarly, the term “below” includes a case where B is directly formed under A and a case where B is formed under A via another.

  According to the present invention, the first interval of the first groove is different from the second interval of the second groove. According to this, the arrangement of the crests and troughs formed by the plurality of first grooves on the first wavy surface, and the crests and troughs formed by the plurality of second grooves on the second wavy surface. Arrangement is relatively difficult to match in the boundary region. Therefore, it is possible to provide a piezoelectric element in which a continuous leak path is hardly formed on the side surface of the piezoelectric layer between the first electrode and the second electrode.

(2) In the piezoelectric element which is one aspect of the present invention,
The first and second intervals may be in the range of 20 nm or more and 500 nm or less.

(3) In the piezoelectric element which is one aspect of the present invention,
A first taper angle of the first wavy surface with respect to the substrate may be smaller than a second taper angle of the second wavy surface with respect to the substrate.

(4) In the piezoelectric element which is one aspect of the present invention,
A coating film that covers at least the side surface of the piezoelectric layer may be included.

(5) A liquid droplet ejecting head which is one of the aspects of the present invention includes:
Any one of the above piezoelectric elements is included.

  According to the present invention, it is possible to provide a liquid droplet ejecting head having a piezoelectric element which is one aspect of the present invention.

(6) A liquid droplet ejecting apparatus which is one aspect of the present invention includes:
The liquid droplet ejecting head is included.

  According to the present invention, it is possible to provide a liquid droplet ejecting apparatus having a liquid droplet ejecting head which is one aspect of the present invention.

(7) A method for manufacturing a piezoelectric element which is one of the aspects of the present invention includes:
Forming a first electrode;
Forming a piezoelectric layer on the first electrode;
Forming a second electrode on the piezoelectric layer;
Including
The step of forming the piezoelectric layer and the second electrode includes:
Forming a piezoelectric film on the first electrode, forming a conductive film on the piezoelectric film, and forming a resist layer on the conductive film;
Using the resist layer as a mask, dry etching the conductive film and the piezoelectric film, and patterning;
Have
In the patterning step, a first etching gas for patterning the conductive film to form the second electrode is a mixed gas containing argon and chlorine and containing chlorine as a main component, and the piezoelectric film The second etching gas that forms the piezoelectric layer by patterning is a mixed gas containing a fluorine-based gas, a chlorine-based gas, and argon.

  According to the present invention, it is possible to provide a method for manufacturing a piezoelectric element which is one of the aspects of the present invention.

(8) In the method for manufacturing a piezoelectric element which is one of the aspects of the present invention,
The dry etching may be performed under a pressure of 1.0 Pa or less.

FIG. 1A is a plan view schematically showing the piezoelectric element of the present embodiment, and FIG. 1B is a cross-sectional view of the piezoelectric element taken along line IB-IB shown in FIG. 2A is a plan view schematically showing a part of the side surface of the piezoelectric layer of the piezoelectric element of this embodiment, and FIG. 2B is a piezoelectric view taken along the line IIB-IIB shown in FIG. Sectional drawing which shows the surface of a body layer typically, FIG.2 (C) is sectional drawing which shows the surface of the piezoelectric material layer in the IIC-IIC line | wire shown to FIG. 2 (A) typically. FIG. 3A and FIG. 3B are cross-sectional views schematically showing modified examples of the piezoelectric element of the present embodiment. FIG. 4A to FIG. 4D are cross-sectional views schematically showing the manufacturing process of the piezoelectric element of this embodiment. FIG. 5A to FIG. 5C are cross-sectional views schematically showing the manufacturing process of the piezoelectric element of this embodiment. FIG. 3 is a cross-sectional view schematically showing a main part of the liquid droplet ejecting head according to the embodiment. FIG. 2 is an exploded perspective view of a liquid droplet ejecting head according to the present embodiment. FIG. 3 is a perspective view schematically showing a droplet ejecting apparatus according to the embodiment. The SEM image which shows the surface state of the side surface of the piezoelectric material layer of the piezoelectric element which concerns on an Example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Piezoelectric element 1-1. Structure of Piezoelectric Element FIG. 1A is a plan view schematically showing the piezoelectric element of this embodiment, and FIG. 1B is a sectional view of the piezoelectric element taken along the line IB-IB shown in FIG. is there. 2A is a plan view schematically showing a part of the side surface of the piezoelectric layer of the piezoelectric element of this embodiment, and FIG. 2B is a piezoelectric view taken along the line IIB-IIB shown in FIG. FIG. 2C is a cross-sectional view schematically showing the surface of the piezoelectric layer taken along the line IIC-IIC shown in FIG. 2A. FIG. 3A and FIG. 3B are cross-sectional views schematically showing modified examples of the piezoelectric element of the present embodiment.

  The piezoelectric element 100 according to this embodiment is formed on the first electrode 20 formed on the substrate 10 and on the first electrode 20 as shown in FIGS. 1A and 1B. The piezoelectric layer 30 and the second electrode 40 formed on the piezoelectric layer 30 are included.

  As shown in FIG. 1A, the piezoelectric element 100 is formed on the substrate 10. As shown in FIG. 1A, the piezoelectric element 100 is formed to extend in one direction. Here, the rectangular shape is formed in the planar view direction, but the shape is not limited to the rectangular shape, and may be a circular shape or a square shape in the planar view direction. Here, the direction in which the piezoelectric element 100 extends is defined as a first direction 110. Further, as shown in FIG. 1, a direction intersecting the first direction with the surface direction of the substrate 10 is a second direction 120. For example, the first direction 110 and the second direction 120 may be substantially orthogonal.

  The board | substrate 10 can be used as the flat member formed with the conductor, the semiconductor, and the insulator, for example. The structure and configuration of the substrate 10 are not particularly limited as long as the substrate 10 is a member that performs mechanical output when the piezoelectric element 100 operates. The substrate 10 may be a diaphragm. The substrate 10 may be a single layer or a structure in which a plurality of layers are stacked. Further, the internal structure of the substrate 10 is not limited as long as the upper surface is planar, and for example, a structure in which a space or the like is formed may be used. The board | substrate 10 may comprise some walls, such as a pressure chamber mentioned later. The thickness of the substrate 10 is optimally selected according to the elastic modulus of the material used. The thickness of the substrate 10 can be, for example, 200 nm or more and 2000 nm or less. If the thickness of the substrate 10 is less than 200 nm, it may be difficult to extract mechanical output such as vibration, and if it is thicker than 2000 nm, vibration or the like may not occur. The substrate 10 can be bent or vibrated by the operation of the piezoelectric layer 30.

  The material of the substrate 10 desirably includes a material having high rigidity and mechanical strength and a material having high adhesion to the first electrode 20 and the piezoelectric layer 30. As a material of the substrate 10, for example, an inorganic oxide such as zirconium oxide, silicon nitride, or silicon oxide, or an alloy such as stainless steel can be used. The substrate 10 may be a laminate including an elastic layer, an adhesion layer, and the like. In the substrate 10, for example, as shown in FIG. 1B, a second layer 12 of zirconium oxide may be formed on the first layer 11 of silicon oxide. Here, although not shown, a third layer for enhancing adhesion such as titanium or chromium may be included on the second layer 12.

  The first electrode 20 is formed on the substrate 10 as shown in FIGS. 1 (A) and 1 (B). The region where the first electrode 20 is formed is not particularly limited as long as it can overlap the piezoelectric layer 30 and the second electrode 40 described later on the substrate 10. For example, as shown in FIG. 1A and FIG. 1B, the first electrode 20 may extend so as not to be partially covered by the piezoelectric layer 30 in the second direction 120. The first electrode 20 is paired with the second electrode 40 and functions as one electrode sandwiching the piezoelectric layer 30. The first electrode 20 may be a lower electrode of the piezoelectric element 100, for example. Although not shown, the first electrode 20 is electrically connected to a lead wiring electrically connected to the drive circuit. An electrical connection method between the first electrode 20 and the lead wiring is not particularly limited.

  The material of the first electrode 20 is not particularly limited as long as it is a conductive material. Examples of the material of the first electrode 20 include various metals such as Ni, Ir, Au, Pt, W, Ti, Ta, Mo, and Cr, alloys of these metals, and conductive oxides thereof (such as iridium oxide). ), A composite oxide of Sr and Ru, a composite oxide of La and Ni, or the like can be used. Further, the first electrode 20 may be a single layer of the exemplified material or may be a structure in which a plurality of materials are stacked.

  The piezoelectric layer 30 is disposed between the first electrode 20 and the second electrode 40 as shown in FIGS. 1 (A) and 1 (B). As shown in FIG. 1A, the piezoelectric layer 30 is formed on the first electrode 20 and the substrate 10. As shown in FIG. 1A, the piezoelectric layer 30 may be formed so as to extend in the first direction 110. As shown in FIG. 1B, the piezoelectric layer 30 includes an upper surface 31 (a surface opposite to the surface on the first electrode 20 side) on which a second electrode 40 described later is formed, and a tapered side surface. (32, 33). The side surfaces (32, 33) are surfaces on which the surface on the first electrode 20 side that is the surface facing the substrate 10 side of the piezoelectric layer 30 and the upper surface 31 are continuous.

As a material of the piezoelectric layer 30, a perovskite oxide represented by the general formula ABO ₃ is preferably used. Specific examples of such materials include lead zirconate titanate (Pb (Zr, Ti) O ₃ ), lead zirconate titanate niobate (Pb (Zr, Ti, Nb) O ₃ ), titanate. Examples thereof include barium (BaTiO ₃ ) and potassium sodium niobate ((K, Na) NbO ₃ ).

  As shown in FIGS. 1 (A) and 1 (B), the side surfaces (32, 33) of the piezoelectric layer 30 have a first wavy surface 32 on the first electrode 20 side and a second electrode 40 described later. A second wavy surface 33 on the side, and a boundary region 34 between the first wavy surface 32 and the second wavy surface 33. A plurality of first grooves 35 extending along the direction from the first electrode 20 toward the boundary region 34 (the vertical direction of the tapered surface) are formed in the first wavy surface 32, and the second wavy surface 33 has A plurality of second grooves 36 extending along the direction from the second electrode 40 toward the boundary region 34 (the vertical direction of the tapered surface) are formed. In the present embodiment, the direction from the first electrode 20 toward the boundary region 34 and the direction from the second electrode 40 toward the boundary region 34 are on a side surface that is a tapered slope (a surface that is not perpendicular to the substrate 10). , It may be a substantially linear direction from the first electrode 20 or the second electrode 40 toward the boundary region 34. For example, the direction from the first electrode 20 or the second electrode 40 toward the boundary region 34 may be a perpendicular direction from the first electrode 20 or the second electrode 40 toward the boundary region 34.

  Here, in FIG. 1 (A), FIG. 2 (A), and the like, the boundary region 34 is shown as a straight line for convenience, but is a region that distinguishes the first wavy surface 32 and the second wavy surface 33. It is not particularly limited as long as it is present, and may be substantially curved. The boundary region 34 may have a constant region width, and may be a transitional region in which the first groove 35 and the second groove 36 are mixed.

  In the present embodiment, the first groove 35 and the second groove 36 mean portions that are substantially recessed in the inner direction of the piezoelectric layer 30 from the upper surface of the side surface. The first groove 35 and the second groove 36 are formed so as to continuously extend in one direction. In other words, the first groove 35 and the second groove 36 in the present embodiment are distinguished from a recess having no directionality in a region where the first groove 35 and the second groove 36 are formed.

  In the following embodiment, a case where the first wavy surface 32 is a rough wavy surface as compared with the second wavy surface 33 will be described as one aspect of the piezoelectric element 100. The form is not limited to this, and the first wavy surface 32 may be a dense wavy surface as compared with the second wavy surface 33.

  2A is a plan view schematically showing the first wavy surface 32 and the second wavy surface 33, and FIG. 2B is a cross-sectional view of the first wavy surface 32, FIG. 2 (C) shows a sectional view of the second wavy surface 33. 2A to 2C, reference numeral 37 indicates a peak portion (vertex portion) of the corrugated surface, and reference numeral 38 indicates a trough portion of the corrugated surface (the deepest portion between adjacent vertex portions). Show. In FIG. 2A, the peak portion 37 is schematically indicated by a solid line, and the valley portion 38 is indicated by a broken line. As shown in FIG. 2A to FIG. 2C, the plurality of first grooves 35 are formed so as to be adjacent to each other, whereby a peak portion 37 and a valley portion 38 are formed on the first wavy surface 32. Alternating wavy surfaces are formed. Also in the 2nd wavy surface 33, as shown to FIG. 2 (A)-FIG.2 (C), when the some 2nd groove | channel 36 is formed adjacently, the peak part 37 and the trough part 38 are formed. A wave-like surface in which is formed alternately is formed. The shape of the first groove 35 and the second groove 36 is not particularly limited as long as a plurality of crests 37 and troughs 38 can be alternately formed, and FIG. 2 (B) and FIG. 2 (C). As shown in FIG. 2, the inner surface of the groove may be a groove formed from a curved surface, or although not shown, the inner surface of the groove may have a corner.

As shown in FIG. 2 (B), the first groove 35 has a first width _{W 1.} The first width W ₁ is the width of the groove in the direction orthogonal to the direction in which the first groove 35 extends, and is the distance between the adjacent peaks 37. Further, as shown in FIG. 2B, the plurality of first grooves 35 are formed adjacent to each other with a _first interval D1. First distance D ₁ is the distance between adjacent troughs 38. Here, the first width W ₁ and the first distance D ₁ may be substantially the same.

In FIG. 2A and FIG. 2B, the first grooves 35 are described so as to be periodically arranged at equal intervals (first intervals D ₁ ). However, FIG. 2A and FIG. 2B are schematically described for the purpose of explaining the first wavy surface 32. In practice, the width (W ₁ ) of the plurality of first grooves 35 and the interval (D ₁ ) adjacent to each other can vary within a certain range. Specifically, the plurality of first intervals D ₁ (first width W ₁ ) may be in a range of 100 nm or more and 500 nm or less. Further, for example, the average value of the plurality of first distance _{D 1} is 100nm or more, it may be in the range below 500 nm.

As shown in FIG. 2 (C), the second groove 36 has a second width _{W 2.} Second width W ₂ of, a width of the groove in a direction perpendicular to the direction in which the second groove 36 extends a distance between adjacent ridges 37. Further, as shown in FIG. 2B, the plurality of second grooves 36 are formed adjacent to each other with a _second interval D2. Second spacing D ₂ is the distance between adjacent troughs 38. Here, the second width W ₂ and the second distance D ₂ may be substantially the same.

As in the case of the first groove 35, in FIGS. 2A and 2C, the second grooves 36 are periodically arranged at the same interval (second interval D ₂ ). As described. However, FIG. 2A and FIG. 2C are schematically described for the purpose of explaining the second wavy surface 33. Substantially, the width (W ₂ ) of the plurality of second grooves 36 and the interval (D ₂ ) adjacent to each other can vary within a certain range. Specifically, the plurality of second intervals D ₂ (second width W ₂ ) may be within a range of 20 nm or more and 100 nm or less. Further, for example, the average value of the plurality of second spacing _{D 2} is 20nm or more, it may be in the range below 100 nm.

As shown in FIG. 2A, the first distance D ₁ of the first groove 35 is different from the second distance D ₂ of the second groove 36. For example, when the first wavy surface 32 is a rougher wavy surface than the second wavy surface 33, the first distance D ₁ is the second groove 36 as shown in FIG. It may be larger than the interval D _{2 of 2} . According to this, as shown in FIG. 2A, in the first wavy surface 32, the arrangement of the crests 37 and the troughs 38 formed by the plurality of first grooves 35, and in the second wavy surface 33, The arrangement of the peak portions 37 and the valley portions 38 formed by the plurality of second grooves 36 is relatively less likely to coincide with each other in the boundary region 34. Therefore, it is difficult to form a continuous leak path on the side surfaces (32, 33) of the piezoelectric layer 30 between the first electrode 20 and the second electrode 40.

  As shown in FIG. 1B, the first and second wavy surfaces 32 and 33 are tapered side surfaces, respectively, when the piezoelectric element 100 is viewed in cross-section along the second direction 120. The taper angle with respect to the substrate 10 may be different. For example, the first taper angle α of the first wavy surface 32 with respect to the substrate 10 may be smaller than the second taper angle β of the second wavy surface 33 with respect to the substrate 10. According to this, when the first taper angle α and the second taper angle β are the same angle, and the first and second wavy surfaces 32 and 33 are planarly continuous (see FIG. 3A). ), The contact area of the surface of the piezoelectric layer 30 on the substrate 10 side with the substrate 10 can be increased. According to this, the connection reliability between the substrate 10 or the first electrode 20 and the piezoelectric layer 30 can be improved without changing the area of the second electrode 40, and the piezoelectric layer 30 can be peeled off. Therefore, the reliability of the piezoelectric element 100 can be improved.

  As shown in FIGS. 1A and 1B, the second electrode 40 is disposed on the upper surface 31 of the piezoelectric layer 30 so as to face the first electrode 20. As shown in FIG. 1B, the region where the second electrode 40 is formed overlaps at least a part of the first electrode 20 on the piezoelectric layer 30, and the driving region ( The region is not particularly limited as long as the region of the piezoelectric layer 30 sandwiched between the first electrode 20 and the second electrode 40 is formed. Therefore, the detailed shape of the second electrode 40 is a design matter when determining the drive region, and can be appropriately determined according to the desired drive region. The second electrode 40 is paired with the first electrode 20 and functions as one electrode sandwiching the piezoelectric layer 30. When the first electrode 20 is a lower electrode, the second electrode 40 may be an upper electrode. The second electrode 40 is electrically connected to a drive circuit (not shown). The electrical connection method between the second electrode 40 and the drive circuit is not particularly limited. For example, as shown in FIG. 1A, the second electrode 40 and the drive circuit may be electrically connected via a lead wiring 60.

  The material of the second electrode 40 is not particularly limited as long as it is a conductive material. Examples of the material of the second electrode 40 include various metals such as Ni, Ir, Au, Pt, W, Ti, Ta, Mo, and Cr, alloys of these metals, and conductive oxides thereof (for example, iridium oxide) ), A composite oxide of Sr and Ru, a composite oxide of La and Ni, or the like can be used. Further, the second electrode 40 may be a single layer of the exemplified materials or may be a structure in which a plurality of materials are stacked.

  As described above, the piezoelectric element 100 according to this embodiment can be configured. In the piezoelectric element 100 according to the present embodiment, the substrate 10 is configured as a diaphragm having a desired elasticity, so that the piezoelectric layer 30 can be deformed by an electric signal and can be pressurized via the substrate 10. You may use as an application of a piezoelectric actuator. In addition, the piezoelectric element 100 according to the present embodiment may be used for other purposes such as a piezoelectric sensor that detects deformation of the piezoelectric layer 30 as an electric signal.

The piezoelectric element 100 according to the present embodiment has, for example, the following characteristics. According to the piezoelectric element according to the present embodiment, the first interval D ₁ of the first groove 35 is different from the second interval D ₂ of the second groove 36. For example, the first distance D ₁ may be larger than the second distance D ₂ of the second groove 36. According to this, the arrangement of the crests 37 and the valleys 38 formed by the plurality of first grooves 35 in the first wavy surface 32, and the plurality of second grooves 36 are formed in the second wavy surface 33. The arrangement of the peak portions 37 and the valley portions 38 is relatively less likely to coincide with each other in the boundary region 34. Therefore, it is possible to provide the piezoelectric element 100 in which a continuous leak path is hardly formed on the side surfaces (32, 33) of the piezoelectric layer 30 between the first electrode 20 and the second electrode 40.

  Next, a modification of the piezoelectric element 100 according to the present embodiment will be described with reference to FIGS. 3 (A) and 3 (B).

  First, as shown in FIG. 3A, the side surfaces (32, 33) of the piezoelectric layer 30 may be planar side surfaces. That is, the first taper angle α of the first wavy surface 32 with respect to the substrate 10 and the second taper angle β of the second wavy surface 33 with respect to the substrate 10 may be the same angle.

  Next, as illustrated in FIG. 3B, the coating film 50 may be formed so as to cover at least the side surfaces (32, 33) of the piezoelectric layer 30. The shape of the coating film 50 is not particularly limited as long as at least the side surfaces (32, 33) of the piezoelectric layer 30 are covered. As shown in FIG. 3B, the coating film 50 has an opening 51 that is open above the drive region of the piezoelectric layer 30 so as to expose at least a part of the second electrode 40. Also good. As shown in FIG. 3B, the coating film 50 continuously covers a part of the first electrode 20, the side surfaces (32, 33) of the piezoelectric layer 30, and a part of the second electrode 40. Also good. Although not shown, the coating film 50 may continuously cover the electrical connection portion between the second electrode 40 and the lead wiring 60. The material of the coating film 50 is not particularly limited as long as it has insulating properties. For example, the coating film 50 can be formed using a known insulating resin material or insulating inorganic material. A known insulating inorganic material may be aluminum oxide or silicon oxide. As a known insulating resin material, for example, a known photosensitive resin material may be used, or a non-photosensitive resin material may be used. When the insulating resin material is a photosensitive resin material, it may also contain a known unsaturated bond-containing polymerizable compound, a photopolymerization initiator, and the like. Specifically, the insulating resin material may be a photoresist or a resin composition such as polyimide, benzocyclobutene (BCB), or a polyvinyl alcohol derivative.

  According to this modification, since the side surfaces (32, 33) of the piezoelectric layer 30 are covered with the coating film 50, the piezoelectric layer 30 can be covered, and deterioration of the piezoelectric element 100 due to the environment is prevented. Reliability can be further increased. In the present modification, the first and second grooves 35 and 36 are continuously formed adjacent to the side surfaces (32 and 33) so that the side surfaces (32 and 33) are wavy. Can be the face of. According to this, the adhesion between the coating film 50 and the side surfaces (32, 33) can be improved.

1-2. Next, a method for manufacturing the piezoelectric element 100 according to the present embodiment will be described. 4A to 5C are cross-sectional views schematically showing the manufacturing process of the piezoelectric element 100 of this embodiment.

  The piezoelectric element manufacturing method according to the present embodiment includes a step of forming the first electrode 20 on the substrate 10, a step of forming the piezoelectric layer 30 on the first electrode 20, Forming the second electrode 40, and forming the piezoelectric layer 30 and the second electrode 40 includes forming the piezoelectric film 30a on the first electrode 20 and forming the piezoelectric film 30a on the piezoelectric film 30a. Forming a conductive layer 40a on the conductive layer 40a, forming a resist layer 70 on the conductive layer 40a, and patterning the conductive layer 40a and the piezoelectric film 30a by dry etching using the resist layer 70 as a mask. .

  First, as shown in FIG. 4A, the first electrode 20 is formed on the substrate 10. The formation method is not particularly limited, and a known film formation method can be used. For example, a conductive film is formed by a vapor deposition method such as a CVD method or a PVD method, a plating method, a sputtering method, a MOD method, or a spin coating method, and the conductive film is patterned by a known patterning method, thereby obtaining a desired shape. The first electrode 20 can be formed. The patterning method can be performed by a known photolithography technique and / or etching technique. When the etching technique is used, wet etching or dry etching can be used.

  Although not shown here, the orientation of an anti-oxidation film such as a titanium nitride film, a piezoelectric film such as a titanium film or a lanthanum nickel oxide film on the first electrode 20 or the substrate 10 is controlled. An orientation control film may be formed. Further, an adhesion layer such as titanium or chromium may be formed between the first electrode 20 and the substrate 10.

  Next, as illustrated in FIG. 4B, a piezoelectric film 30 a is formed on the first electrode 20. The piezoelectric layer 30a is formed by forming a piezoelectric material and performing a heat treatment. The film formation method is not particularly limited, and a known film formation method can be used. The heat treatment condition is not particularly limited as long as it is a temperature at which the piezoelectric material can be crystallized to form the piezoelectric film 30a. The heat treatment can be performed, for example, at 500 ° C. or more and 800 ° C. or less in an oxygen atmosphere. For example, the piezoelectric film 30a can be formed by forming a piezoelectric material formed by a sol-gel method or the like and then performing heat treatment. The piezoelectric film 30a may be formed by spin coating, CVD, MOD, sputtering, laser ablation, or the like.

  Next, as shown in FIG. 4C, a conductive film 40a to be patterned to form the second electrode 40 is formed on the piezoelectric film 30a. The formation method of the conductive film 40a is not particularly limited, and a known film formation method can be used. For example, the conductive film 40a can be formed by a vapor deposition method such as a CVD method or a PVD method, a plating method, a sputtering method, a MOD method, or a spin coating method.

  Next, as illustrated in FIG. 4D, a resist layer 70 is formed over the conductive film 40a. The material of the resist layer 70 is not particularly limited, and a known resist material used for dry etching can be used. As shown in FIG. 4D, the resist layer 70 has a desired thickness and includes side surfaces 71.

  Next, as shown in FIGS. 5A and 5B, the conductive film 40a and the piezoelectric film 30a are patterned by dry etching using the resist layer 70 as a mask. Here, in the patterning step of the conductive film 40a and the piezoelectric film 30a, the first etching gas for patterning the conductive film 40a to form the second electrode 40 includes chlorine gas and argon gas, and contains chlorine gas. The second etching gas, which is a mixed gas containing main components and forms the piezoelectric layer 30 by patterning the piezoelectric film 30a, is a mixed gas containing a chlorine-based gas, a fluorine-based gas, and an argon gas. Details will be described below.

  The patterning process of the conductive film 40a is performed by a known dry etching technique. As a known dry etching technique, for example, dry etching using a high-density plasma apparatus such as ICP (Inductively Coupled Plasma) may be performed. In the high-density plasma apparatus (dry etching apparatus), when the pressure is set to 1.0 Pa or less, etching can be performed satisfactorily. As a first etching gas used for dry etching of the conductive film 40a, a mixed gas containing chlorine gas (Cl) and argon gas (Ar) and containing chlorine as a main component is used. That is, the first etching gas may be a mixed gas having the largest mixing ratio of chlorine. For example, the mixing ratio (Cl / Ar) of chlorine gas (Cl) and argon gas (Ar) in the first etching gas may be 30/20, 40/10, or the like. As a result, the second electrode 40 is formed, and the side surface 71 of the resist layer 70 is formed with a wavy surface in which a plurality of grooves are adjacent.

Next, the patterning process of the piezoelectric film 30a is performed by a known dry etching technique, similarly to the conductive film 40a. As a known dry etching technique, for example, dry etching using a high-density plasma apparatus such as ICP (Inductively Coupled Plasma) may be performed. In the high-density plasma apparatus (dry etching apparatus), when the pressure is set to 1.0 Pa or less, etching can be performed satisfactorily. As the second etching gas used for dry etching of the piezoelectric film 30a, a mixed gas containing a chlorine-based gas as a main component can be used. For example, BCl ₃ / C ₄ F ₈ / Ar can be used, and the mixing ratio can be 30/20/10. Here, the patterning process of the piezoelectric film 30a is performed using the resist layer 70 that has undergone the dry etching process using the first etching gas as a mask. As described above, the side surface 71 of the resist layer 70 is a wavy surface in which a plurality of grooves are adjacent to each other, whereby the piezoelectric layer 30 having the first and second wavy surfaces 32 and 33 is formed. Can do.

  Here, as shown in FIG. 5B, first and second wavy surfaces 32 and 33 having different taper angles with respect to the substrate 10 are formed on the side surfaces of the piezoelectric layer 30. Here, the shape of the piezoelectric layer 30 such as the arrangement of the first wavy surface 32, the second wavy surface 33, the boundary region 34, and the respective taper angles is appropriately adjusted by adjusting the dry etching time. can do. For example, by making the dry etching time longer, the first taper angle α and the second taper angle β can be made closer to each other.

  Here, as shown in FIG. 5B, when the piezoelectric film 30a is patterned by dry etching, the surface layer of the first electrode 20 where the piezoelectric film 30a is removed is affected by the dry etching. According to this, the surface layer of the first electrode 20 is scraped by dry etching, and the conductive particles may adhere to the surrounding member (for example, the side surface of the piezoelectric layer 30). However, according to the piezoelectric element 100 according to the present embodiment, as described above, a continuous leak path is formed on the side surfaces (32, 33) of the piezoelectric layer 30 between the first electrode 20 and the second electrode 40. Hateful. Therefore, even when dry etching is used, it is possible to suppress the occurrence of leak current due to the side surface adhesion of the conductive particles.

  Next, as shown in FIG. 5C, after the patterning process is completed, the resist layer 70 is removed. Through the above steps, the piezoelectric element 100 can be manufactured.

  The method for manufacturing the piezoelectric element 100 according to the present embodiment has the following features, for example. According to the method for manufacturing the piezoelectric element 100 according to the present embodiment, the piezoelectric element 100 according to the present embodiment can be provided.

2. Next, a droplet ejecting head 600 having the piezoelectric element 100 according to the present embodiment will be described with reference to the drawings. FIG. 6 is a cross-sectional view schematically showing a main part of the droplet ejecting head 600 according to the present embodiment. FIG. 7 is an exploded perspective view of the droplet ejecting head 600 according to the present embodiment, which is shown upside down from a state in which it is normally used.

  The droplet ejecting head 600 can include the above-described piezoelectric element 100 (piezoelectric actuator). In the following example, a droplet ejecting head 600 in which the substrate 10 is formed as a vibration plate and the piezoelectric element 100 is configured as a piezoelectric actuator will be described.

  As shown in FIGS. 6 and 7, the droplet ejection head 600 includes a nozzle plate 610 having nozzle holes 612, a pressure chamber substrate 620 for forming the pressure chamber 622, and the piezoelectric element 100.

  The number of piezoelectric elements 100 is not particularly limited, and a plurality of piezoelectric elements 100 may be formed. When a plurality of piezoelectric elements 100 are formed, the second electrode 40 becomes a common electrode. When a plurality of piezoelectric elements 100 are formed, the first electrode 20 becomes a common electrode. Further, the droplet ejecting head 600 can include a housing 630 as shown in FIG. In FIG. 7, the piezoelectric element 100 is illustrated in a simplified manner.

  As shown in FIGS. 6 and 7, the nozzle plate 610 has nozzle holes 612. The nozzle holes 612 include liquids such as ink (not only liquids but also various functional materials adjusted to an appropriate viscosity with a solvent or dispersion medium, or those containing metal flakes, etc.). .) Can be ejected as droplets. In the nozzle plate 610, for example, a number of nozzle holes 612 are provided in a line. Examples of the material of the nozzle plate 620 include silicon and stainless steel (SUS).

  The pressure chamber substrate 620 is provided on the nozzle plate 610 (below in the example of FIG. 7). Examples of the material of the pressure chamber substrate 620 include silicon. As the pressure chamber substrate 620 divides the space between the nozzle plate 610 and the substrate 10, as shown in FIG. 7, a reservoir (liquid storage unit) 624, a supply port 626 communicating with the reservoir 624, and a supply port A pressure chamber 622 communicating with 626 is provided. In this example, the reservoir 624, the supply port 626, and the pressure chamber 622 are distinguished from each other. However, these are all flow paths for liquids and the like, and no matter how the flow paths are designed. I do not care. Further, for example, the supply port 626 has a shape in which a part of the flow path is narrowed in the illustrated example, but can be arbitrarily formed according to the design, and is not necessarily an essential configuration. The reservoir 624, the supply port 626, and the pressure chamber 622 are partitioned by the nozzle plate 610, the pressure chamber substrate 620, and the substrate 10. The reservoir 624 can temporarily store ink supplied from the outside (for example, an ink cartridge) through a through hole 628 provided in the substrate 10. The ink in the reservoir 624 can be supplied to the pressure chamber 622 via the supply port 626. The volume of the pressure chamber 622 changes due to the deformation of the substrate 10. The pressure chamber 622 communicates with the nozzle hole 612, and liquid or the like is discharged from the nozzle hole 612 when the volume of the pressure chamber 622 changes.

  The piezoelectric element 100 is provided on the pressure chamber substrate 620 (lower in the example of FIG. 7). The piezoelectric element 100 is electrically connected to a piezoelectric element driving circuit (not shown), and can operate (vibrate or deform) based on a signal from the piezoelectric element driving circuit. The substrate 10 can be deformed by the operation of the laminated structure (piezoelectric layer 30), and the internal pressure of the pressure chamber 622 can be appropriately changed.

  As shown in FIG. 7, the housing 630 can accommodate the nozzle plate 610, the pressure chamber substrate 620, and the piezoelectric element 100. Examples of the material of the housing 630 include resin and metal.

  The droplet ejection head 600 includes the piezoelectric element 100 in which a continuous leak path is difficult to be formed on the side surfaces (32, 33) of the piezoelectric layer 30. Therefore, it is possible to realize a droplet ejection head with improved reliability.

  Here, the case where the droplet ejecting head 600 is an ink jet recording head has been described. However, the liquid droplet ejecting head of the present invention is, for example, an electrode material ejecting head used for forming electrodes of a color material ejecting head, an organic EL display, an FED (surface emitting display), etc. It can also be used as a bio-organic matter ejecting head used for biochip manufacturing.

3. Next, the droplet ejecting apparatus according to the present embodiment will be described with reference to the drawings. The droplet ejecting apparatus has the above-described droplet ejecting head. Hereinafter, a case where the droplet ejecting apparatus is an inkjet printer having the above-described droplet ejecting head 600 will be described. FIG. 8 is a perspective view schematically showing a droplet ejecting apparatus 700 according to the present embodiment.

  As illustrated in FIG. 8, the droplet ejecting apparatus 700 includes a head unit 730, a driving unit 710, and a control unit 760. Further, the droplet ejecting apparatus 700 is disposed on the upper surface of the apparatus main body 720, the apparatus main body 720, the paper feed unit 750, the tray 721 on which the recording paper P is set, the discharge port 722 for discharging the recording paper P. An operation panel 770.

  The head unit 730 includes an ink jet recording head (hereinafter, also simply referred to as “head”) constituted by the droplet ejecting head 600 described above. The head unit 730 further includes an ink cartridge 731 that supplies ink to the head, and a transport unit (carriage) 732 on which the head and the ink cartridge 731 are mounted.

  The drive unit 710 can reciprocate the head unit 730. The drive unit 710 includes a carriage motor 741 serving as a drive source for the head unit 730, and a reciprocating mechanism 742 that receives the rotation of the carriage motor 741 and reciprocates the head unit 730.

  The reciprocating mechanism 742 includes a carriage guide shaft 744 supported at both ends by a frame (not shown), and a timing belt 743 extending in parallel with the carriage guide shaft 744. The carriage guide shaft 744 supports the carriage 732 while allowing the carriage 732 to freely reciprocate. Further, the carriage 732 is fixed to a part of the timing belt 743. When the timing belt 743 is caused to travel by the operation of the carriage motor 741, it is guided to the carriage guide shaft 744 and the head unit 730 reciprocates. During this reciprocation, ink is appropriately discharged from the head, and printing on the recording paper P is performed.

  Note that in this embodiment, an example is shown in which printing is performed while both the droplet ejecting head 600 and the recording paper P move, but the droplet ejecting apparatus of the present invention has the droplet ejecting head 600 and the recording paper. It may be a mechanism in which P is printed on the recording paper P while changing its position relative to each other. Further, in the present embodiment, an example is shown in which printing is performed on the recording paper P. However, the recording medium that can be printed by the liquid droplet ejecting apparatus of the present invention is not limited to paper, but is a cloth or film. A wide range of media such as metal can be used, and the configuration can be changed as appropriate.

  The control unit 760 can control the head unit 730, the drive unit 710, and the paper feed unit 750.

  The paper feeding unit 750 can feed the recording paper P from the tray 721 to the head unit 730 side. The paper feed unit 750 includes a paper feed motor 751 serving as a drive source thereof, and a paper feed roller 752 that rotates by the operation of the paper feed motor 751. The paper feed roller 752 includes a driven roller 752a and a drive roller 752b that face each other up and down across the feeding path of the recording paper P. The drive roller 752b is connected to the paper feed motor 751. When the paper supply unit 750 is driven by the control unit 760, the recording paper P is sent so as to pass below the head unit 730.

  The head unit 730, the drive unit 710, the control unit 760, and the paper feed unit 750 are provided inside the apparatus main body 720.

  The droplet ejection device 700 includes the piezoelectric element 100 in which a continuous leak path is difficult to be formed on the side surfaces (32, 33) of the piezoelectric layer 30. Therefore, a droplet ejecting apparatus with improved reliability can be realized.

  Note that the liquid droplet ejecting apparatus exemplified above has one liquid droplet ejecting head, and this liquid droplet ejecting head can perform printing on a recording medium, but has a plurality of liquid droplet ejecting heads. May be. When the droplet ejecting apparatus has a plurality of droplet ejecting heads, the plurality of droplet ejecting heads may be operated independently as described above, or the plurality of droplet ejecting heads are connected to each other. Thus, it may be a single head. An example of such a set of heads is a line-type head in which nozzle holes of a plurality of heads have a uniform interval as a whole.

As described above, the ink jet recording apparatus 700 as an ink jet printer has been described as an example of the liquid droplet ejecting apparatus according to the present invention. However, the liquid droplet ejecting apparatus according to the present invention can be used industrially. As the liquid or the like (liquid material) discharged in this case, various functional materials adjusted to an appropriate viscosity with a solvent or a dispersion medium can be used. In addition to the exemplified image recording apparatus such as a printer, the liquid droplet ejecting apparatus of the present invention includes a color material ejecting apparatus, an organic EL display, an FED (surface emitting display), an electrophoresis used for manufacturing a color filter such as a liquid crystal display. It can also be suitably used as a liquid material ejecting apparatus used for forming electrodes such as displays and color filters, and a bioorganic material ejecting apparatus used for biochip manufacturing.

4). Examples Hereinafter, examples of the piezoelectric element according to the present invention will be described with reference to the drawings.

In the examples, a piezoelectric element sample was manufactured using the method for manufacturing a piezoelectric element according to the present embodiment, and the surface state (SEM image) of the side surfaces (32, 33) was confirmed. The piezoelectric element created in this example is formed on a silicon (Si) substrate, which is a substrate, and a first electrode containing platinum (Pt) and iridium (Ir) is formed to a thickness of 200 nm. A piezoelectric layer made of lead zirconate titanate (Pb (Zr, Ti) O ₃ ) is formed on the first electrode with a thickness of 1300 nm, and then a second electrode made of iridium (Ir) is formed. The film was formed with a thickness of 50 nm.

In the manufacturing process of the piezoelectric element according to this embodiment, the first etching gas is a mixed gas composed of chlorine gas (Cl ₂ ) and argon gas (Ar) (mixing ratio is Cl ₂ : Ar = 3: 2). Was used. As the second etching gas, a mixed gas composed of a chlorine-based gas (BCl ₃ ), a fluorine-based gas (C ₄ F ₈ ), and an argon gas (Ar) (mixing ratio is BCl ₃ : C ₄ F ₈ : Ar = 3: 2: 1) was used.

  FIG. 9 is an SEM image of the piezoelectric element according to the example, and shows the surface state of the side surface of the piezoelectric layer of the piezoelectric element sample according to the present example. However, FIG. 9 is an SEM image after patterning of the piezoelectric layer, and the resist layer is not removed.

  As shown in FIG. 9, on the side surface of the piezoelectric layer of the piezoelectric element sample according to the example, the first wavy surface on the first electrode side (rough wavy surface as compared with the second wavy surface), and the first The second wavy surface on the two-electrode side (dense wavy surface as compared with the first wavy surface) and the boundary region between them were confirmed. As shown in FIG. 9, it was confirmed that a plurality of first grooves extending in the direction of the boundary region from the first electrode side are formed on the first wavy surface. Further, as shown in FIG. 9, it was confirmed that a plurality of second grooves extending in the direction of the boundary region from the second electrode side are formed on the first wavy surface. Moreover, as shown in FIG. 9, it was confirmed that the 1st space | interval in which a 1st groove | channel is formed differs from the 2nd space | interval in which a 2nd groove | channel is formed. Further, as shown in FIG. 9, it was confirmed that the first taper angle of the first wavy surface with respect to the substrate was different from the second taper angle of the second wavy surface with respect to the substrate.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10 substrate (vibration plate), 20 first electrode, 30 piezoelectric layer, 30a piezoelectric film,
31 upper surface, 32 first wavy surface, 33 second wavy surface, 34 boundary region,
35 1st groove, 36 2nd groove, 37 mountain part, 38 valley part, 40 2nd electrode,
40a conductive film, 50 coating film, 60 lead wiring, 70 resist layer,
100 piezoelectric elements, 110 first direction, 120 second direction,
600 droplet ejection head, 610 nozzle plate, 612 nozzle hole,
620 pressure chamber substrate, 622 pressure chamber, 624 reservoir, 626 supply port,
628 through-hole, 630 housing, 700 droplet ejection device, 710 drive unit,
720 device main body, 721 tray, 722 discharge port, 730 head unit,
731 Ink cartridge, 732 carriage, 741 carriage motor,
742 reciprocating mechanism, 743 timing belt, 744 carriage guide shaft,
750 paper feed unit, 751 paper feed motor, 752 paper feed roller,
752a driven roller, 752b drive roller, 760 controller,
770 Operation panel

Claims (8)

A first electrode;
A piezoelectric layer formed on the first electrode;
A second electrode formed on the piezoelectric layer;
Including
The side surface of the piezoelectric layer includes a first wavy surface in which a plurality of first grooves extending in a direction from the first electrode toward the second electrode are formed, and the first wavy surface than the first wavy surface. A second wavy surface provided on the two-electrode side and formed with a plurality of second grooves extending in a direction from the first electrode toward the second electrode; the first wavy surface; The boundary area with the wavy surface;
Have
The piezoelectric element, wherein a first interval of the first groove is different from a second interval of the second groove. In claim 1,
The piezoelectric element, wherein the first and second intervals are in the range of 20 nm or more and 500 nm or less. In claim 1 or 2,
A piezoelectric element, wherein a first taper angle of the first wavy surface with respect to the substrate is smaller than a second taper angle of the second wavy surface with respect to the substrate. In any one of Claim 1 to 3,
A piezoelectric element comprising a coating film covering at least the side surface of the piezoelectric layer.   A liquid droplet ejecting head comprising the piezoelectric element according to claim 1.   A droplet ejecting apparatus comprising the droplet ejecting head according to claim 5. Forming a first electrode on the substrate;
Forming a piezoelectric layer on the first electrode;
Forming a second electrode on the piezoelectric layer;
Including
The step of forming the piezoelectric layer and the second electrode includes:
Forming a piezoelectric film on the first electrode, forming a conductive film on the piezoelectric film, and forming a resist layer on the conductive film;
Using the resist layer as a mask, dry etching the conductive film and the piezoelectric film, and patterning;
Have
In the patterning step, a first etching gas for patterning the conductive film to form the second electrode is a mixed gas containing argon and chlorine and containing chlorine as a main component, and the piezoelectric film The method of manufacturing a piezoelectric element, wherein the second etching gas that forms the piezoelectric layer by patterning is a mixed gas containing a fluorine-based gas, a chlorine-based gas, and argon. In claim 7,
The method for manufacturing a piezoelectric element, wherein the dry etching is performed under a pressure of 1.0 Pa or less.