JP2014058082A - Piezoelectric element, droplet discharge head, liquid cartridge, and droplet discharge recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a leak current between an upper electrode and a lower electrode in a piezoelectric element.SOLUTION: A piezoelectric element 116 includes: a lower electrode 117; a piezoelectric material 118 which is disposed on the lower electrode 117; and an upper electrode 119 disposed on the piezoelectric material 118. The upper electrode 119 has an upper surface area smaller than an upper surface area of the piezoelectric material 118 and is disposed so as to be spaced away from a side surface of the piezoelectric material 118. The piezoelectric material 118 includes a recessed part 130, which is disposed enclosing a periphery of the upper electrode 119, on its upper surface. A bottom surface of the recessed part 130 is located adjacent to the side surface of the piezoelectric material 118. A conductive etching product material 131 created during patterning of the upper electrode 119 exists at a region of the upper surface of the piezoelectric material 118 and a side surface of the upper electrode 119 which are located between the upper electrode 119 and the recessed part 130. The etching product material 131 is not formed in the recessed part 130.

Description

  The present invention relates to a piezoelectric element, a droplet discharge head, a liquid cartridge, and a droplet discharge recording apparatus, and in particular, a piezoelectric element in which a lower electrode, a piezoelectric body and an upper electrode are laminated, and a droplet discharge head and a liquid using the piezoelectric element. The present invention relates to a cartridge and a droplet discharge recording apparatus.

  Examples of the droplet discharge head include a droplet discharge head that discharges a liquid resist as droplets, a droplet discharge head that discharges a DNA (deoxyribonucleic acid) sample as droplets, and a droplet discharge head that discharges ink as droplets. Etc.

  Among them, an ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile machine, a copying apparatus, or a plotter has a nozzle for ejecting ink droplets and an individual liquid chamber (an ink flow path, And an ink jet head as a droplet discharge head equipped with a discharge chamber, a pressurized liquid chamber, and a flow path) and a driving means (pressure generating means) for pressurizing ink in the liquid chamber. Is. Hereinafter, the description will focus on the inkjet head.

  The ink jet recording apparatus has many advantages such as extremely low noise during recording, high-speed printing, and the ability to use inexpensive plain paper with a high degree of freedom of ink. Among them, a so-called ink-on-demand system that ejects ink droplets only when recording is necessary does not require the collection of ink droplets that are not necessary for recording, and is currently mainstream.

  Ink-on-demand ink jet heads have a driving means that is a piezoelectric element (see, for example, Patent Document 1), or a method of heating ink to generate bubbles and ejecting ink with that pressure (see FIG. For example, refer to Patent Document 2), and those using electrostatic force as driving means (for example, refer to Patent Document 3).

  Among them, as a piezoelectric element system, there is a system that uses a thin film piezoelectric body formed by using a sol-gel method or the like in recent years. A system using PZT (lead zirconate titanate) as a piezoelectric body is called a thin film PZT system. The piezoelectric element has a structure in which a lower electrode, a piezoelectric body, and an upper electrode are laminated.

  A piezoelectric element including a thin film piezoelectric body can be easily miniaturized because the piezoelectric body can be patterned by applying semiconductor manufacturing technology. In addition, a piezoelectric element including a thin film piezoelectric body is formed as an integrated structure by applying semiconductor manufacturing technology and MEMS (Micro Electro Mechanical Systems) technology as an actuator including an ink flow path portion and a diaphragm portion. There are also advantages such as what you can do.

  However, there are various problems inherent in the piezoelectric element including the thin film piezoelectric body. One of the problems is a leakage current between the upper electrode and the lower electrode for applying a driving voltage to the piezoelectric body. As miniaturization progresses, further countermeasures are required in the future.

  Needless to say, in order to cope with the inter-electrode leakage current, first, it is necessary to ensure physical insulation between the electrodes. Therefore, the relative positional relationship (shape) of the lower electrode, the piezoelectric body, and the upper electrode constituting the driving unit is important.

  For example, a structure is known in which the upper electrode and the piezoelectric body have the same projected area (upper surface area) in order to increase the driving efficiency of the piezoelectric body (see, for example, Patent Document 4). This structure is advantageous in terms of man-hour and cost because the upper electrode and the piezoelectric body can be formed by batch etching in terms of construction. However, since the side surface of the upper electrode and the side surface of the piezoelectric body are arranged on the same surface, there is a concern of leakage current via the conductive etching product caused by the upper electrode and the lower electrode attached to these side surfaces.

  A structure in which the upper electrode projected area is smaller than the piezoelectric projected area is known (see, for example, Patent Document 5). This structure is disadvantageous in terms of man-hours and costs because it is necessary to form the upper electrode and the piezoelectric body separately. However, in this structure, the upper electrode side surface and the piezoelectric body side surface are not on the same plane. Therefore, compared with the structure disclosed in Patent Document 4, this structure is less susceptible to etching products when the upper electrode is formed, and is advantageous in terms of interelectrode leakage current.

  FIG. 11 is a schematic cross-sectional view for explaining a conventional piezoelectric element and an example of a manufacturing process thereof. First, the configuration of a conventional piezoelectric element will be described with reference to FIG.

  The piezoelectric element 401 is formed on the base member 402. The piezoelectric element 401 includes a lower electrode 403 formed on the base member 402, a piezoelectric body 404 disposed on the lower electrode 403, and an upper electrode 405 disposed on the piezoelectric body 404. The upper surface area of the upper electrode 405 is smaller than the upper surface area of the piezoelectric body 404. The side surface of the upper electrode 405 is disposed at a distance from the side surface of the piezoelectric body 404.

  A conductive etching product 406 generated during patterning of the upper electrode 405 is present in the region on the upper surface of the piezoelectric body 404 between the side surface of the piezoelectric body 404 and the upper electrode 405 and in the side surface of the upper electrode 405. A conductive etching product 407 generated during patterning of the piezoelectric body 404 is present on the side surface of the piezoelectric body 404.

  With reference to FIG. 11, an example of the formation process of the piezoelectric element 401 will be described. The parentheses for each step described below correspond to the parentheses in FIG.

(1) On the base member 402, a lower electrode film 403a, a piezoelectric film 404a, and an upper electrode film 405a are sequentially stacked to form a film. A resist pattern 408 for defining the formation position of the upper electrode is formed on the upper electrode film 405a.

(2) The upper electrode film 405a is patterned using the resist pattern 408 as a mask to form the upper electrode 405. At this time, the etching product 406 adheres to the surface of the piezoelectric film 404a, the side surface of the upper electrode 405, and the side surface of the resist pattern 408. Since the upper electrode film 405a to be etched is conductive, the etching product 406 is also conductive.

(3) The resist pattern 133 is removed. A predetermined cleaning process is performed. The etching product 406 is not completely removed even if a removal process is performed by a resist removal process or a subsequent cleaning process, and part of the etching product 406 remains on the side surfaces of the upper electrode 405 and the surface of the piezoelectric film 404a.

  A resist pattern 409 for defining a formation region of the piezoelectric body 404 is formed. The piezoelectric film 404a is formed by patterning the piezoelectric film 404a using the resist pattern 409 as a mask. At this time, a part of the underlying lower electrode film 403a is also etched, so that the conductive etching product 407 adheres to the side surfaces of the piezoelectric body 404 and the resist pattern 409.

(4) The resist pattern 409 is removed. A resist pattern for defining a formation region of the lower electrode 403 is formed, and the lower electrode film 403a is patterned using the resist pattern as a mask to form the lower electrode 403. Thereafter, the resist pattern is removed.

  In the conventional piezoelectric element 401, as shown in FIG. 11 (4), the upper electrode 405 and the lower electrode 403 are brought into conduction through the conductive etching products 406 and 407. , 405, a leakage current flows. Therefore, the piezoelectric element 401 causes a malfunction. When such a piezoelectric element 401 is applied to a droplet discharge head, a characteristic failure of the droplet discharge head is caused due to a malfunction of the piezoelectric element 401.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a piezoelectric element that can prevent the occurrence of a leakage current between an upper electrode and a lower electrode, a droplet discharge head using the same, and a liquid To provide a cartridge and a droplet discharge recording apparatus.

  A piezoelectric element according to the present invention includes a lower electrode, a piezoelectric body disposed on the lower electrode, and an upper electrode disposed on the piezoelectric body, and the upper electrode has an upper surface area of the piezoelectric element. Smaller than the upper surface area of the body and spaced from the side surface of the piezoelectric body, the piezoelectric body having a recess disposed on the upper surface surrounding the periphery of the upper electrode, the upper electrode and the A conductive etching product generated during the patterning of the upper electrode exists in the region of the upper surface of the piezoelectric body between the recesses and the side surface of the upper electrode, and the etching product is formed in the recesses. It is not.

  A droplet discharge head according to the present invention includes a nozzle layer having a plurality of nozzle holes, a flow path layer that forms a liquid chamber communicating with the nozzle holes, and a pressure applied to the fluid flowing in the liquid chamber via a diaphragm. A droplet discharge head having a piezoelectric element to be generated, wherein the piezoelectric element is the piezoelectric element of the present invention.

  The liquid cartridge according to the present invention is a liquid cartridge in which a liquid droplet ejection head that ejects liquid droplets and a liquid tank that supplies liquid to the liquid droplet ejection head are integrated, and the liquid droplet ejection head is a liquid cartridge according to the present invention. It is a droplet discharge head.

  A droplet discharge recording apparatus according to the present invention is a droplet discharge recording apparatus including a droplet discharge head for discharging droplets, and the droplet discharge head is the droplet discharge head of the present invention. .

  The piezoelectric element of the present invention includes a recess disposed on the upper surface of the piezoelectric body so as to surround the periphery of the upper electrode, and a conductive etching product generated during patterning of the upper electrode is not formed in the recess. Therefore, generation of a leakage current between the upper electrode and the lower electrode due to the etching product can be prevented.

  Since the droplet discharge head according to the present invention includes the piezoelectric element according to the present invention, a decrease in yield due to the piezoelectric element is reduced, reliability related to the piezoelectric element is improved, and as a result, the yield and overall yield of the droplet discharge head are reduced. Reliability can be improved.

  Since the liquid cartridge of the present invention includes the liquid droplet ejection head of the present invention, a decrease in yield due to the liquid droplet ejection head is reduced, and the reliability of the liquid droplet ejection head is improved. Reliability can be improved.

  Since the droplet discharge recording apparatus of the present invention includes the droplet discharge head of the present invention, a decrease in yield due to the droplet discharge head is reduced, and the reliability of the droplet discharge head is improved. The reliability of the entire droplet discharge recording apparatus can be improved.

It is a schematic exploded perspective view for explaining one example of a droplet discharge head. It is a schematic sectional drawing for demonstrating the Example. It is sectional drawing which expanded and showed a part of FIG. It is a schematic sectional drawing for demonstrating one Example of the piezoelectric element, and its formation process example. It is a schematic sectional drawing for demonstrating other Examples of a piezoelectric element, and the example of the formation process. It is a schematic perspective view for demonstrating one Example of a liquid cartridge. 1 is a schematic perspective view for explaining an embodiment of a droplet discharge recording apparatus. It is a side view for demonstrating the mechanism part of the Example. It is a schematic sectional drawing for demonstrating other Example of a piezoelectric element. It is a schematic sectional drawing for demonstrating other Example of a piezoelectric element. It is a schematic sectional drawing for demonstrating the piezoelectric element of a prior art, and its formation process example.

  FIG. 1 is a schematic exploded perspective view for explaining an embodiment of a droplet discharge head. FIG. 2 is a schematic cross-sectional view for explaining the embodiment. 2 corresponds to the position AA in FIG. FIG. 3 is an enlarged cross-sectional view of a part of FIG. 2 and 3 are upside down with respect to FIG. 1 for convenience. In FIG. 3, the nozzle cover, the packing plate, and the damper plate are not shown.

  In this embodiment, the piezoelectric element of the present invention is applied to a droplet discharge head, but the droplet discharge head to which the piezoelectric element of the present invention is applied is not limited to the droplet discharge head of this embodiment. Further, the apparatus to which the piezoelectric element of the present invention is applied is not limited to the droplet discharge head.

  An inkjet head 101 that is a droplet discharge head includes a nozzle cover 102, a nozzle plate (nozzle layer) 103, an actuator substrate 104, a backing plate 105, a damper plate 106, a frame 107, and an FPC (Flexible printed circuits) 108. The nozzle plate 103, the actuator substrate 104, the backing plate 105, and the damper plate 106 are stacked in that order and fixed to the frame 107 by the nozzle cover 102.

  A large number of nozzle holes 109, which are fine holes for causing ink droplets to fly, are formed in the nozzle plate 103. A flow path substrate (flow path layer) 111 including individual liquid chambers 110 that individually communicate with the nozzle holes 109 is formed on the actuator substrate 106. The individual liquid chamber 110 includes a pressurized liquid chamber section 112, a fluid resistance section 113, and an ink supply section 114.

The nozzle hole 109 is arranged corresponding to the tip position of the pressurized liquid chamber 105 of the corresponding individual liquid chamber 110. The diameter of the nozzle hole 102 is, for example, 10 to 35 μm (micrometer).
The nozzle plate 103 is formed of a resin film such as polyimide, for example. Further, as a material of the nozzle plate 103, for example, a nickel metal plate manufactured by an electroforming method, silicon, or other metal material can be used. The nozzle plate 103 is formed with a water-repellent surface treatment film.

  The individual liquid chamber 110 is formed as a part of the actuator substrate 104, and is formed by processing a flow path substrate 111 made of, for example, silicon. The individual liquid chamber 110 is provided for each nozzle hole 109. For example, the flow path substrate 111 is formed by a photolithography technique and a silicon deep digging dry etching technique using a fluorine-based gas by an ICP (Inductively Coupled Plasma) etcher. Usually, an etching process for forming the individual liquid chamber 110 on the flow path substrate 111 is performed after a drive element portion on the surface of the actuator substrate 104 described later is formed and the silicon substrate thickness is reduced to about 100 μm by backside polishing. Done.

  In the actuator substrate 104, a diaphragm 115 is disposed on the flow path substrate 111. A piezoelectric element 116 is formed on the diaphragm 115. The diaphragm 115 is a part for transmitting the pressure generated by the piezoelectric element 116 to the ink in the pressurized liquid chamber 112. The diaphragm 115 is made of, for example, a single film or a composite film such as a silicon oxide film, a silicon nitride film, or a polysilicon film, and is formed using a diffusion furnace, a CVD (Chemical Vapor Deposition) apparatus, or the like. The film thickness of the diaphragm 115 is, for example, about 0.5 to 3 μm as the total film thickness of the laminated films.

  The piezoelectric element 116 includes a lower electrode 117, a piezoelectric body 118 disposed on the lower electrode 117, and an upper electrode 119 disposed on the piezoelectric body 118. In this embodiment, the lower electrode 117 is used as a common electrode for the plurality of piezoelectric elements 116, and the upper electrode 119 is used as an individual electrode for each piezoelectric element 116.

  The piezoelectric body 118 of the piezoelectric element 116 is displaced (deformed) by the voltage supplied from the lower electrode 117 and the upper electrode 119. The diaphragm 115 is displaced by the displacement of the piezoelectric body 118, and the pressure in the pressurized liquid chamber 108 changes.

The material of the piezoelectric body 118 is, for example, PZT (lead zirconate titanate) formed by a sol-gel method. The film thickness of the piezoelectric body 118 is, for example, about 1 to 2 μm. However, the material and film thickness of the piezoelectric body 118 are not limited to this. For example, the material of the piezoelectric body 118 includes BaTiO ₃ (barium titanate) in addition to PZT.

  Examples of the material of the lower electrode 117 and the upper electrode 119 include low resistance materials such as Pt (platinum), Au (gold), and In (indium). The lower electrode 117 and the upper electrode 119 are formed by, for example, a sputtering method, a photolithography technique, and an etching technique. The film thickness of the lower electrode 117 and the upper electrode 119 is, for example, about 100 to 200 nm (nanometers). Note that the materials of the lower electrode 117 and the upper electrode 119 may be different from each other. Further, the film thickness of the lower electrode 117 and the film thickness of the upper electrode 119 may be different from each other.

  An interlayer insulating film 120 is formed on the vibration plate 115 so as to cover the piezoelectric element 116. A wiring 121 is formed on the interlayer insulating film 120. The wiring 121 and the upper electrode 119 are electrically connected through a connection hole provided in the interlayer insulating film 120.

  The interlayer insulating film 120 is, for example, a laminated film of a silicon oxide film by an ALD (atomic layer deposition) method and a silicon oxide film by a plasma CVD method. The total film thickness of the laminated films constituting the interlayer insulating film 120 is, for example, 0.5 to 1 μm.

  The material of the wiring 121 is aluminum, for example. The wiring 121 is formed by, for example, a sputtering method, a photoengraving technique, and an etching technique. The film thickness of the wiring 121 is, for example, 1 to 3 μm.

A passivation film 122 is formed on the interlayer insulating film 120 so as to cover the wiring 121. The passivation film 122 blocks the internal structure of the actuator substrate 104 from the outside air. A pad opening 124 for electrical connection with the external input 123 is formed in the passivation film 122 on the pad portion of the wiring 121.
The material of the passivation film 122 is, for example, a silicon nitride film formed by plasma CVD. The thickness of the passivation film 122 is, for example, 0.7 to 1.5 μm.

  The external input 123 is, for example, an IC (Integrated Circuit) chip. The external input 123 controls voltage application to the piezoelectric element 116 via the wiring 121. The external input 123 is electrically connected to the outside of the inkjet head 101 via the FCP 108 shown in FIG. The connection method between the pad portion of the wiring 121 and the external input 123 is, for example, a stud bump method. However, the external input 123 and the connection method are not limited to these.

  A protective substrate 126 is disposed on the passivation film 122 via an adhesive 125. The protective substrate 126 is for complementing the rigidity of the actuator substrate 104. The protective substrate 126 includes a recess 127 that covers a region where the piezoelectric element 116 is formed, and an ink supply hole 128 that is a through-hole that communicates with the ink supply unit 114 of the individual liquid chamber 110. The ink supply hole 128 communicates with the ink supply unit 114 through a through hole formed in the passivation film 122, the interlayer insulating film 120, and the diaphragm 115.

  For example, the protective substrate 126 is formed by processing a silicon substrate having a thickness of about 400 μm. For example, the protective substrate 126 is formed by a photolithography technique and a silicon deep digging dry etching technique using a fluorine-based gas by an ICP etcher.

Next, the ink flow will be described.
The ink supplied to the ink supply hole 216 flows into the pressurized liquid chamber portion 112 via the ink supply portion 114 and the fluid resistance portion 113 of the individual liquid chamber 110. The pressurized liquid chamber 112 is filled with ink.

  Displacement occurs in the piezoelectric body 118 when an input (voltage) from the external input 123 mounted on the actuator substrate 104 is applied to the upper electrode 119 of the piezoelectric element 116 via the wiring 121. The lower electrode 117 is an electrically grounded circuit (not shown). The displacement of the piezoelectric body 118 generates a pressure in the pressurized liquid chamber 112 through the vibration plate 115. As a result, the ink droplet 129 is ejected from the nozzle hole 109.

  FIG. 4 is a schematic cross-sectional view for explaining a piezoelectric element and an example of the formation process thereof in this embodiment. First, the configuration of the piezoelectric element will be described with reference to FIG.

  A piezoelectric element 116 is formed on a diaphragm 115 as a base member. The piezoelectric element 116 includes a lower electrode 117, a piezoelectric body 118 disposed on the lower electrode 117, and an upper electrode 119 disposed on the piezoelectric body 118.

  The upper surface area of the upper electrode 119 is smaller than the upper surface area of the piezoelectric body 118. Further, the end portion of the upper electrode 119 is disposed with a distance from the side surface of the piezoelectric body 118.

  The piezoelectric body 118 includes a concave portion 130 disposed on the upper surface thereof so as to surround the upper electrode 119. In this embodiment, the bottom surface of the recess 130 is adjacent to the side surface of the piezoelectric body 118. However, the bottom surface of the recess 130 may be spaced from the side surface of the piezoelectric body 118.

  A conductive etching product 131 generated during patterning of the upper electrode 119 exists in the region on the upper surface of the piezoelectric body 118 between the upper electrode 119 and the recess 130 and on the side surface of the upper electrode 119. The etching product 131 is not formed in the recess 130.

  A conductive etching product 132 generated during patterning of the piezoelectric body 118 is present on the outer peripheral side surface of the piezoelectric body 118. Note that the etching product 132 may not exist in the piezoelectric element 116, for example, when the lower electrode 117 is disposed only at a position directly below the piezoelectric body 118.

  The etching products 131 and 132 are drawn with a uniform film thickness in FIG. 4, but are not limited thereto. The etching products 131 and 132 may vary in film thickness at each arrangement position, or may be formed in spots. Here, the patchy state refers to a state where a region where the etching products 131 and 132 are arranged and a region where the etching products 131 and 132 are not arranged are mixed.

  With reference to FIG. 4, an example of a process for forming the piezoelectric element 116 will be described. The parentheses for each step described below correspond to the parentheses in FIG.

(1) On the silicon substrate (not shown) for forming the flow path substrate 111, the diaphragm 115, the lower electrode film 117a, the piezoelectric film 118a, and the upper electrode film 119a are sequentially stacked. For example, a resist pattern 133 for defining the formation position of the upper electrode is formed on the upper electrode film 119a by photolithography.

(2) For example, the upper electrode film 119a is patterned by a dry etching technique using a chlorine-based gas and the resist pattern 133 as a mask to form the upper electrode 119. At this time, the etching product 131 adheres to the surface of the piezoelectric film 118a, the side surface of the upper electrode 119, and the side surface of the resist pattern 133. Since the upper electrode film 119a to be etched is conductive, the etching product 131 is also conductive.

(3) The resist pattern 133 is removed. A predetermined cleaning process is performed. The etching product 131 is not completely removed even if a removal process by a resist removal process or a subsequent cleaning process is obtained, and a part remains on the side surface of the upper electrode 119 and the surface of the piezoelectric film 118a.

  For example, a resist pattern 134 for defining a formation region of the recess 130 (see (5)) is formed by photolithography. The resist pattern 134 covers the upper electrode 119. For example, sputter etching is performed using a fluorine-based gas and a high bias voltage. As a result, the conductive etching product 131 remaining on the surface of the piezoelectric film 118a is removed by etching in a region not covered with the resist pattern 134. In addition, a recess 130 is formed on the surface of the piezoelectric film 118a.

(4) The resist pattern 134 is removed. For example, a resist pattern 135 for defining the formation region of the piezoelectric body 118 is formed by photolithography. The resist pattern 135 covers the recess 130, the upper electrode 119, and the etching product 131 located in the formation region of the piezoelectric body 118.

  For example, the piezoelectric body 118 is formed by patterning the piezoelectric film 118a using the resist pattern 135 as a mask by a dry etching technique using a fluorine-based gas. At this time, a part of the underlying lower electrode film 117a is also etched, so that the conductive etching product 132 adheres to the side surfaces of the piezoelectric body 118 and the resist pattern 135.

(5) The resist pattern 135 is removed. For example, a resist pattern (not shown) that covers the piezoelectric body 118 and the upper electrode 119 and defines a formation region of the lower electrode 117 is formed by photolithography. For example, the lower electrode 117 is formed by patterning the lower electrode film 117a using the resist pattern as a mask by a dry etching technique using a chlorine-based gas. At this time, a conductive etching product is generated. However, since the piezoelectric body 118 and the upper electrode 119 are covered with the resist pattern, the etching product does not adhere to the piezoelectric body 118 and the upper electrode 119. Thereafter, the resist pattern is removed.

  Through the above steps, the piezoelectric element 116 is formed. In the piezoelectric element 116, the piezoelectric body 118 includes a recess 130 disposed on the upper surface thereof so as to surround the upper electrode 119. A conductive etching product 131 exists in a region on the upper surface of the piezoelectric body 118 between the upper electrode 119 and the recess 130 and in a side surface of the upper electrode 119. In addition, a conductive etching product 132 exists on the outer peripheral side surface of the piezoelectric body 118. However, the etching products 131 and 132 are not formed in the recess 130. Therefore, the piezoelectric element 116 can prevent the occurrence of leakage current between the lower electrode 117 and the upper electrode 119 via the conductive etching products 131 and 132. The inkjet head 101 (see FIGS. 2 and 3) provided with the piezoelectric element 116 can obtain good head characteristics.

  FIG. 5 is a schematic cross-sectional view for explaining another embodiment of the piezoelectric element and an example of the formation process thereof. First, the configuration of the piezoelectric element of this embodiment will be described with reference to FIG. 5, parts having the same functions as those in FIG. 4 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  The piezoelectric element 116 of this embodiment includes an insulating film 136 formed on the upper surface of the piezoelectric body 118. The insulating film 136 covers the upper electrode 119, the etching product 131, and the recess 130. The insulating film 136 is not formed on the side surface of the piezoelectric body 118.

  With reference to FIG. 5, the example of a formation process of a piezoelectric element is demonstrated. The parentheses for each step described below correspond to the parentheses in FIG. Steps (1) to (3) in this example of the forming step are the same as steps (1) to (3) described with reference to FIG.

(4) After removing the resist pattern 134, a predetermined cleaning process is performed. Using an ALD film forming apparatus, an insulating film 136 made of an ALD silicon oxide film covering the upper electrode 118, the etching product 131, and the recess 130 is formed on the piezoelectric film 118a in which the recess 130 is formed. The film thickness of the insulating film 136 is, for example, about 50 nm. However, the structure of the insulating film 136 is not limited to this. The insulating film 136 may be formed of other materials, or may be a laminated film including a plurality of insulating films.

(5) A resist pattern 135 for defining a formation region of the piezoelectric body 118 is formed on the insulating film 136 by, for example, photolithography. For example, the piezoelectric body 118 is formed by patterning the piezoelectric film 118a using the resist pattern 135 as a mask by a dry etching technique using a fluorine-based gas. At this time, a part of the underlying lower electrode film 117a is also etched, so that the conductive etching product 132 is attached to the side surface of the piezoelectric body 118, the side surface of the insulating film 136, and the side surface of the resist pattern 135.

(6) The resist pattern 135 is removed. The lower electrode 117 is formed in the same manner as the step (5) described with reference to FIG. A conductive etching product is generated when the lower electrode 117 is etched. However, since the piezoelectric body 118, the upper electrode 119, and the insulating film 136 are covered with a resist pattern, the etching product is the piezoelectric body 118, the upper electrode 119. And it does not adhere to the insulating film 136.

  Through the above steps, the piezoelectric element 116 including the insulating film 136 is formed. Similar to the piezoelectric element 116 described with reference to FIG. 4 (5), the piezoelectric element 116 including the insulating film 136 includes a recess 130 disposed on the upper surface of the piezoelectric body 118 so as to surround the upper electrode 119. ing. Further, the etching products 131 and 132 are not formed in the recess 130. Therefore, the piezoelectric element 116 provided with the insulating film 136 can also prevent the occurrence of leakage current between the lower electrode 117 and the upper electrode 119 via the etching products 131 and 132. The inkjet head 101 (see FIGS. 2 and 3) provided with the piezoelectric element 116 can obtain good head characteristics.

Further, the insulating film 136 seals the upper electrode 119 before the lower electrode film 117a is exposed. Therefore, the piezoelectric element 116 provided with the insulating film 136 can more reliably prevent the occurrence of leakage current between the lower electrode 117 and the upper electrode 119.
Furthermore, by covering the upper surface of the piezoelectric body 118 with the insulating film 136, it is possible to reduce the thermal influence on the piezoelectric body 118 in a later process than the process of forming the insulating film 136. Thereby, the piezoelectric body 118 with higher reliability is formed. Further, by applying the piezoelectric element 116 including the insulating film 136 to the inkjet head 101 (see FIGS. 2 and 3), better head characteristics can be obtained.

FIG. 6 is a schematic perspective view for explaining an embodiment of the liquid cartridge.
The liquid cartridge 201 is obtained by integrating the droplet discharge head 203 of the above-described embodiment having the nozzle 202 and the like, and the liquid tank 204 that supplies liquid to the droplet discharge head 203.

  Thus, in the case of the liquid tank integrated head, the performance of the droplet discharge head 203 immediately leads to the performance of the entire liquid cartridge 201. Therefore, by using the highly reliable droplet discharge head 203, the reliability is high. A liquid cartridge 201 can be obtained.

  FIG. 7 is a schematic perspective view for explaining an embodiment of the droplet discharge recording apparatus. FIG. 8 is a side view for explaining the mechanism of this embodiment.

  The droplet discharge recording apparatus 301 includes a carriage that can move in the main scanning direction inside the recording apparatus main body 302, a recording head that includes the droplet discharge head that implements the present invention mounted on the carriage, and ink that supplies ink to the recording head. A printing mechanism 303 composed of a cartridge or the like is accommodated. In the droplet discharge recording apparatus 301, a sheet feeding cassette (or a sheet feeding tray) 305 capable of stacking a large number of sheets 304 from the front side can be detachably attached to the lower part of the apparatus main body 302. . Further, the droplet discharge recording apparatus 301 can open the manual feed tray 306 for manually feeding the paper 304. The droplet discharge recording device 301 takes in the paper 304 fed from the paper feed cassette 305 or the manual feed tray 306, records a required image by the printing mechanism unit 303, and then onto a paper discharge tray 307 mounted on the rear side. Eject paper.

  The printing mechanism section 303 holds the carriage 310 slidably in the main scanning direction (perpendicular to the paper surface in FIG. 8) with a main guide rod 308 and a sub guide rod 309, which are guide members horizontally mounted on left and right side plates (not shown). doing. The carriage 310 includes a recording head including a droplet discharge head according to the present invention that discharges yellow (Y), cyan (C), magenta (M), and black (Bk) ink droplets. Nozzles) are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward. Each ink cartridge 312 for supplying ink of each color to the recording head is replaceably mounted on the carriage 310.

  The ink cartridge 312 has an air port that communicates with the atmosphere upward, a supply port that supplies ink to the inkjet head below, and a porous body filled with ink inside, and the capillary force of the porous body. Thus, the ink supplied to the inkjet head is maintained at a slight negative pressure. Further, although the recording heads of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  Here, the carriage 310 is slidably fitted to the main guide rod 308 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 302 on the front side (upstream side in the paper conveyance direction). It is location. In order to move and scan the carriage 310 in the main scanning direction, a timing belt 316 is stretched between a driving pulley 314 and a driven pulley 315 that are rotationally driven by a main scanning motor 313. The carriage 310 is fixed to the timing belt 316, and the carriage 310 is reciprocated by forward and reverse rotation of the main scanning motor 313.

  In order to convey the sheet 304 set in the sheet feeding cassette 305 to the lower side of the recording head, a sheet feeding roller 317, a friction pad 318, a guide member 319, a conveying roller 320, a conveying roller 321 and a leading end roller 322 are provided. . A paper feed roller 317 and a friction pad 318 separate and feed the paper 304 from the paper feed cassette 305. A guide member 319 guides the sheet 304. The conveyance roller 320 inverts and conveys the fed sheet 304. The conveyance roller 321 is pressed against the peripheral surface of the conveyance roller 320. The leading end roller 322 defines the feed angle of the sheet 304 from the transport roller 320. The conveyance roller 320 is rotationally driven by a sub-scanning motor 323 through a gear train.

  A printing receiving member 324 is provided as a paper guide member for guiding the paper 304 fed from the conveying roller 320 below the recording head 311 corresponding to the range of movement of the carriage 310 in the main scanning direction. On the downstream side of the printing receiving member 324 in the sheet conveyance direction, a conveyance roller 325 and a spur 326 that are rotationally driven to send out the sheet 304 in the sheet discharge direction are provided. Further, a paper discharge roller 327 and a spur 328 for sending the paper 304 to the paper discharge tray 307, and guide members 329 and 330 for forming a paper discharge path are provided.

  At the time of recording, the recording head 311 is driven according to the image signal while moving the carriage 310 to eject ink onto the stopped paper 304 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 304 has reached the recording area, the recording operation is terminated and the sheet 304 is discharged.

  A recovery device 331 for recovering the ejection failure of the recording head is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 310. The recovery device 331 includes a cap unit, a suction unit, and a cleaning unit. The carriage 310 is moved to the recovery device 331 side during printing standby, and the recording head is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  In case of ejection failure, etc., the ejection port (nozzle) of the recording head is sealed with a capping unit, air bubbles are sucked out together with ink from the ejection port with a suction unit through the tube, and ink or dust adhered to the ejection port surface Is removed by the cleaning means to recover the ejection failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, the droplet discharge recording apparatus 301 is equipped with the droplet discharge head 311 embodying the present invention. Since the performance of the droplet discharge head 311 immediately leads to the overall performance of the droplet discharge recording device 301, the highly reliable droplet discharge recording device 301 can be obtained by using the highly reliable droplet discharge head 311. Can do.

  In the above embodiment, the liquid droplet ejection head of the present invention is applied to an ink jet head. However, the present invention can also be applied to a liquid droplet ejection head that ejects liquid droplets other than ink, for example, a liquid resist for patterning.

  As mentioned above, although the Example of this invention was described, the numerical value, material, arrangement | positioning, number, etc. in the said Example are examples, This invention is not limited to these, It was described in the claim Various modifications are possible within the scope of the present invention.

  For example, in the piezoelectric element 116 of the above embodiment, the bottom surface of the recess 130 is adjacent to the side surface of the piezoelectric body 118, but the piezoelectric element of the present invention is not limited to this. For example, as shown in FIG. 10 or FIG. 11, the bottom surface of the recess 130 may be spaced from the side surface of the piezoelectric body 118. These structures can be formed by changing the opening formation position of the resist pattern 134 in the formation process example described with reference to FIG. 4 or FIG.

  In the configuration shown in FIG. 10 or 11, the etching product 131 is also present on the surface of the piezoelectric body 118 between the side surface of the piezoelectric body 118 and the recess 130. However, since the etching product 131 is not formed in the recess 130, generation of a leakage current between the lower electrode 117 and the upper electrode 119 is prevented.

  In addition, the bottom surface of the concave portion 130 includes a portion adjacent to the side surface of the piezoelectric body 118 and a portion not adjacent to the side surface of the piezoelectric body 118, such as a configuration adjacent to the side surface of one side, two sides, or three sides of the piezoelectric body 118. It may be mixed.

  In the above embodiment, the piezoelectric element 116 is mounted on the actuator substrate 104 of the inkjet head 101, but the apparatus to which the piezoelectric element of the present invention is applied is not limited to this. The piezoelectric element according to the present invention may be any piezoelectric element as long as the piezoelectric element has a configuration including a lower electrode, a piezoelectric body disposed on the lower electrode, and an upper electrode disposed on the piezoelectric body. Even applicable.

  Further, the droplet discharge head of the present invention is not limited to the configuration of the inkjet head 101. The liquid droplet ejection head of the present invention generates a pressure through a diaphragm in a nozzle layer having a plurality of nozzle holes, a flow path layer that forms a liquid chamber communicating with the nozzle holes, and a fluid flowing in the liquid chamber. Any droplet discharge head having any configuration can be applied as long as the droplet discharge head includes a piezoelectric element to be operated.

  In the droplet discharge head of the present invention, a plurality of nozzle holes may be arranged in one liquid chamber.

101 Inkjet head (droplet discharge head)
103 Nozzle plate (nozzle layer)
109 Nozzle hole 110 Liquid chamber 115 Diaphragm 116 Piezoelectric element 117 Lower electrode 118 Piezoelectric body 119 Upper electrode 130 Recess 131 Etching product 136 Insulating film

Japanese Examined Patent Publication No. 2-51734 Japanese Patent Publication No. 61-59911 Japanese Patent Laid-Open No. 5-50601 JP 2004-074806 A JP 2010-219153 A

Claims (6)

A lower electrode;
A piezoelectric body disposed on the lower electrode;
An upper electrode disposed on the piezoelectric body,
The upper electrode has an upper surface area smaller than the upper surface area of the piezoelectric body, and is disposed at a distance from a side surface of the piezoelectric body,
The piezoelectric body includes a recess disposed on an upper surface thereof so as to surround the upper electrode,
In the region of the upper surface of the piezoelectric body between the upper electrode and the recess and the side surface of the upper electrode, there is a conductive etching product generated during patterning of the upper electrode,
The piezoelectric element is characterized in that the etching product is not formed in the recess. An insulating film that covers the upper electrode, the etching product, and the recess is formed on the upper surface of the piezoelectric body,
The piezoelectric element according to claim 1, wherein the insulating film is not formed on a side surface of the piezoelectric body.   The piezoelectric element according to claim 1, wherein a bottom surface of the recess is adjacent to a side surface of the piezoelectric body. A droplet having a nozzle layer having a plurality of nozzle holes, a flow path layer forming a liquid chamber communicating with the nozzle holes, and a piezoelectric element for generating a pressure in the fluid flowing in the liquid chamber via a vibration plate In the discharge head,
A droplet discharge head, wherein the piezoelectric element is the piezoelectric element according to claim 1. In a liquid cartridge in which a droplet discharge head that discharges droplets and a liquid tank that supplies liquid to the droplet discharge head are integrated,
A liquid cartridge, wherein the droplet discharge head is the droplet discharge head according to claim 4. In a droplet discharge recording apparatus equipped with a droplet discharge head for discharging droplets,
A droplet discharge recording apparatus, wherein the droplet discharge head is the droplet discharge head according to claim 4.