JP5058717B2 - Liquid discharge head and manufacturing method thereof - Google Patents

Description

  The present invention relates to a liquid discharge head that discharges a desired liquid by applying energy from the outside to the liquid and a method for manufacturing the same. The liquid discharge head according to the present invention can be applied to an ink jet recording head that prints on paper, cloth, leather, nonwoven fabric, OHP sheet, etc., a patterning device that applies liquid to a solid material such as a substrate or a plate, a coating device, and the like. is there. Hereinafter, the ink jet recording head will be described as a representative.

  Printers using an ink jet recording apparatus as a printing apparatus for personal computers are widely used because of their good printing performance and low cost. In this ink jet recording apparatus, bubbles are generated in ink by heat energy, ink droplets are ejected by pressure waves caused by the bubbles, ink droplets are sucked and discharged by electrostatic force, pressure by a vibrator such as a piezoelectric element, etc. Those using waves have been developed.

  Among the above-described ink jet recording apparatuses, those using piezoelectric elements have an ink flow path communicating with an ink discharge port and a pressure generating chamber communicated with the ink flow path. When a predetermined voltage is applied to the diaphragm film piezoelectric thin film provided in the pressure generating chamber and joined with the piezoelectric thin film, the piezoelectric thin film expands and contracts. The expansion and contraction of the piezoelectric thin film causes the piezoelectric thin film and the diaphragm film to vibrate together to pressurize and compress the ink in the pressure generating chamber, thereby ejecting ink droplets from the ink ejection openings. This is the configuration.

  In such an ink jet recording head, with the recent demand for higher definition of image formation, higher integration is achieved by arranging a large number of pressure source sources such as ink pressure chambers of a flow path substrate and piezoelectric elements. It has been broken.

  In order to meet these demands, in a piezo-type ink jet recording head, for example, an electrode or a piezoelectric body is formed on the entire surface of the vibration plate by a film forming technique, and an electrode or a piezoelectric body corresponding to the ink pressure chamber using a photolithography technique. The one which processes is proposed. A high-density ink jet recording head is realized by using a film forming technique and a photolithography technique. Further, by using a Si substrate or a metal member for the flow path substrate or the orifice plate, it is possible to form a highly accurate flow path or discharge port.

  Generally, the piezoelectric body is processed so as to correspond to each ink pressure chamber and to have a width narrower than the width of the ink pressure chamber. Any piezoelectric material that does not correspond to the ink pressure chamber is removed. In recent years, a dry etching technique using a chlorine-based gas or the like has been introduced to process these piezoelectric bodies. Compared with wet etching with hydrofluoric acid or an acid-based solution, the etching rate and etching shape are easy to control, and high-precision processing is possible.

  As a method for improving the withstand voltage of a piezoelectric element, Patent Document 1 discloses a technique of laminating a Pb-containing perovskite material and a non-Pb-containing perovskite material. Patent Document 2 discloses a technique for protecting a lower electrode by forming a piezoelectric layer in a step shape.

Patent Document 3 discloses a technique for preventing destruction of a piezoelectric layer by inserting an interlayer insulating layer between an upper electrode and a lower electrode of an electrode drawn out from a piezoelectric element.
Japanese Patent Laid-Open No. 2004-186574 JP-A-9-277519 JP 2000-37868 A

  When processing the piezoelectric body by the dry etching method, if the lower electrode is not patterned, the lower electrode serves as an etching stop layer. When the piezoelectric body is processed in such a configuration, the lower electrode is also etched slightly. In particular, when a Pt electrode is used as the lower electrode, a considerable amount of the Pt electrode is etched by hitting the Pt surface with chlorine gas used for piezoelectric processing.

  In particular, when a difficult-to-etch material such as lead zirconate titanate (PZT) is used as the piezoelectric body, etching conditions with strong sputter-like elements are often used. At this time, if the lower electrode is exposed during the etching of the piezoelectric body, the lower electrode material may be sputtered and adhere to the end face of the processed piezoelectric body. If metal adheres to the end face of the piezoelectric body, it may cause a short circuit between the upper and lower electrodes and destruction of the piezoelectric thin film.

  Further, if the lower electrode in the vicinity of the piezoelectric thin film serving as the drive unit is exposed, there is a problem that a short circuit occurs between the upper and lower electrodes during driving, or the electrode and the piezoelectric thin film are destroyed.

  Furthermore, since the piezoelectric body generally has a high dielectric constant, the capacitance as the element is large, the response speed to the drive waveform is slow, and the drive waveform for precise ejection may not be able to follow. In particular, the capacitance at the lead-out portion for wiring is essentially unnecessary, and there is a need to reduce it.

  Therefore, the object of the present invention is to solve the above-mentioned problems, suppress the breakdown of electrodes and piezoelectric bodies and the occurrence of shorts between the upper and lower electrodes, have high reliability, enable high-speed response, and enable precise discharge control. It is an object of the present invention to provide a liquid discharge head and a manufacturing method thereof.

The liquid discharge head of the present invention is
A plurality of pressure chambers that communicate with a discharge port that discharges the liquid and pressurizes the liquid; a lower electrode that is provided corresponding to each of the plurality of pressure chambers and stacked in order from the pressure chamber side; and a piezoelectric body A plurality of piezoelectric elements each having a layer and an upper electrode, wherein the lower electrode is provided in a corresponding region between the plurality of pressure chambers, wherein at least the plurality of pressure chambers An insulator layer that covers all of the lower electrode provided in a region corresponding to each other is formed, and provided in a region corresponding to the space between the plurality of pressure chambers in the insulator layer. The thickness of the portion is smaller than the thickness of the portion provided in the region corresponding to the piezoelectric layer in the insulator layer .

Furthermore, the manufacturing method of the liquid discharge head of the present invention includes:
A plurality of pressure chambers that communicate with a discharge port that discharges the liquid and pressurizes the liquid; a lower electrode that is provided corresponding to each of the plurality of pressure chambers and stacked in order from the pressure chamber side; and a piezoelectric body includes a plurality of piezoelectric element having a layer and the upper electrode, wherein the plurality of the lower electrode to the corresponding region between the adjacent pressure chambers is provided, an insulating the lower electrode provided in at least the region A method of manufacturing a liquid ejection head that is entirely covered by a body layer, the step of forming an insulator layer on the lower electrode, and the step of forming a material layer of the piezoelectric layer on the insulator layer; Of the material layer of the piezoelectric layer, a portion corresponding to the space between the plurality of pressure chambers is etched to form the plurality of piezoelectric layers, and the plurality of pressures of the insulator layer Exposing portions provided in corresponding areas between the chambers; The thickness, out of said insulator layer, characterized in that it comprises a a step of less than the thickness of the portion provided in a region corresponding to the piezoelectric layer.

  As described above, according to the present invention, impurities are not attached to the side wall of the piezoelectric body during the processing of the liquid discharge head, and the withstand voltage between the upper and lower electrodes is improved, resulting in high yield and high durability. Further, it is possible to obtain a liquid ejection head that is highly reliable and capable of high-speed response and capable of precise ejection control.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view of an ink jet recording head as a liquid ejection head of this embodiment. A Si wafer is used as the substrate. On a Si substrate 101, a SiO ₂ layer (box layer) 102, a Si single crystal layer (SOI layer) 103 as a diaphragm, a SiO ₂ layer 104, a lower electrode 105 as a piezoelectric element, an insulator layer (hereinafter referred to as “insulating layer”) 106, a piezoelectric layer 109, and an upper electrode 108 are sequentially formed.

The insulating layer 106 is electrically insulative capable of withstanding high temperatures such as Al ₂ O ₃ , AlN, Si ₃ N ₄ , SiO ₂ , MgO, Ta ₂ O ₅ , SiC, YSZ, ZrO ₂ , HfAlO, HfO _2, etc. A high film is used. The insulating layer 106 preferably has a higher dielectric constant than that of the piezoelectric layer 107 so that a larger electric field strength is applied to the piezoelectric layer 107 when laminated on the piezoelectric layer 107. Furthermore, since the insulating layer 106 is used as an etching stop layer, it is desirable that the etching rate be higher than that of the piezoelectric layer 107. In addition, the thinner the insulating layer 106 is, the smaller the voltage is not applied, but it is desirable that the insulating layer 106 be formed as a film and have a film thickness that is not destroyed by a strong electric field. Specifically, the film thickness is desirably 20 to 200 nm, and more desirably 40 to 200 nm.

  As the piezoelectric layer 107, a piezoelectric body having a perovskite structure mainly composed of lead zirconate titanate, relaxor, or barium titanate is used.

  A hole is formed in the substrate 101 by etching in order to form the ink pressure chamber 111 under the vibration plate. Further, an orifice Si substrate 113 is bonded, and an ink discharge port 112 is formed in accordance with the ink pressure chamber 111.

  The structure of the ink pressure chamber 111 for pressurizing the ink is not limited to the one described here as long as the ink pressure chamber 111 is manufactured by combining etching and pasting and can effectively wait for the ink to discharge.

  The vibration plate is formed on the ink pressure chamber 111, a partition partitioning the ink pressure chamber 111, and the partition. The insulating layer 106 is also formed on the partition between adjacent piezoelectric elements. That is, the insulating layer 106 is formed so as to cover all the lower electrodes 105 provided in the corresponding regions between the plurality of ink pressure chambers.

  In addition to the insulator layer 106 on the lower electrode, the insulator layer 106 may be positioned below the upper electrode 108 as shown in FIG. FIG. 2 is a schematic cross-sectional view in the longitudinal direction of a recording head according to another embodiment. In this embodiment, the insulating layer 106 is also provided below the upper electrode 108 in the wiring portion shown in the drawing. With this configuration, it is possible to more reliably prevent occurrence of a short circuit between the lower electrode 105 and the upper electrode 108 and to significantly reduce the capacitance of the wiring portion.

Next, a process example of the ink jet recording head according to the present invention will be described step by step with reference to FIGS. 3A and 3B.
(1) A thermal oxide film (SiO ₂ layer) 104 is formed on a silicon substrate 101 having an SOI layer 103 by thermal oxidation treatment.
(2) On this thermal oxide film 104, Pt / Ti is formed as a lower electrode 105 by sputtering or the like, and an insulating film 106 is further deposited thereon by LPCVD or sputtering. The lower electrode 105 has a thickness of 300 to 1000 mm, and the insulating layer 106 has a thickness of about 1000 to 1 μm.
(3) A thin film mainly composed of lead zirconate titanate or barium titanate is deposited on the insulating film 106 by a method such as sputtering or CVD, and fired at 600 to 800 ° C. to form the piezoelectric layer 107. The material layer. A metal such as Pt / Ti is deposited on the piezoelectric layer 107 and patterned to form the upper layer electrode 108.
(4) The piezoelectric layer 107 is etched to form the piezoelectric element 109. At this time, the insulating layer 106 is used as an etching stop layer by a dry etching method. By using the insulating layer 106 as an etching stop layer, it is possible to prevent Pt / Ti or the like of the lower electrode 105 from being overetched and adhering to the end face of the piezoelectric element 109. By this dry etching, at least the insulating layer between the piezoelectric elements is exposed.

The insulating layer 106 where the surface is exposed (exposed) by dry etching is preferably thinner than the insulating layer 106 below the piezoelectric layer 107. This is because the restraint of the entire diaphragm becomes smaller as the exposed insulating layer 106 is thinner.
(5) After resist patterning, an ink pressure chamber 111 is formed below the piezoelectric element portion using an ICP (Inductively Coupled Plasma) etching method.
(6) An ink discharge port 112 is formed on another silicon substrate using the ICP method, and an orifice plate 113 is formed.
(7) The aforementioned parts are joined to complete the ink jet recording head 114.
[Example 1-1]
FIG. 1 is a schematic sectional view of an ink jet recording head showing the present embodiment. A silicon SOI wafer is used as the substrate. On a 200 μm-thick Si substrate 101, an SiO ₂ layer (box layer) 102 was formed with a thickness of 1 μm, a Si single crystal layer (SOI layer) 103 as a vibration plate was formed with a thickness of 5 μm, and an SiO ₂ layer 104 was formed with a thickness of 3000 mm. Further, as a piezoelectric element, a lower electrode 105, an insulating film 106, a piezoelectric layer 109, and an upper electrode 108 were sequentially formed with the following thicknesses. The lower electrode 105 was Pt / Ti = 3000/300 ／, and the insulating film 106 was Al ₂ O ₃ = 4000Å. The piezoelectric layer 109 was Pb (Zr, Ti) O ₃ perovskite oxide (PZT) = 2.7 μm, and the upper electrode 108 was Pt / Ti = 3000/300 ＝.

  A hole was formed in the substrate 101 by etching to form an ink pressure chamber 111 under the diaphragm. Further, an orifice silicon substrate 113 having a thickness of 200 μm was bonded, and an ink discharge port 112 having a diameter of 40 μmφ was formed in accordance with the ink pressure chamber.

  The width of the ink pressure chamber was 100 μm, the depth was 3 mm, and the pitch between the elements was 120 μm.

Using this head, a 3 pl droplet at 30 KHz and a print test with a width of 12.5 mm were performed using aqueous ink with a viscosity of 2 cp, and a high-quality printed matter without ejection failure was obtained up to 2 × 10 ¹⁰ times. It was.
[Comparative Example 1-1]
FIG. 4 is a schematic cross-sectional view of an ink jet recording head manufactured for comparison with the present invention. An element similar to that of Example 1 was manufactured except that the insulating film 106 was not provided. When this head was used and a printing test was performed with a water droplet having a viscosity of 2 cp and a droplet of 3 pl at 30 KHz and a width of 12.5 mm, a non-ejection portion occurred at 5 × 10 ⁹ times.
[Example 1-2]
As shown in FIG. 5, the insulating layer 106 was over-etched to reduce the film thickness 114 of the portion other than under the piezoelectric layer 107 to 2000 mm. Other structures were the same as in Example 1-1. When the deformation of the actuator portion was measured, the displacement when a voltage of 30 V was applied was 8% larger than that of Example 1. In the printing test, a high-quality printed matter having no ejection up to 2 × 10 ¹⁰ times was obtained.
[Example 1-3]
Next, the process of the ink jet recording head according to the present invention will be described in order with reference to FIGS. 3A and 3B again.
(1) On a silicon substrate 101 having a thickness of 200 μm having a 1 μm box layer 102 and a 5 μm SOI layer 103, a thermal oxide film (SiO ₂ layer) 104 having a thickness of 3000 mm was formed by thermal oxidation.
(2) On this, Pt / Ti = 3000 / 300Å was formed as a lower electrode 105 by sputtering, and 3000Å of Ta ₂ O ₅ was deposited thereon as an insulating film 106 by sputtering.
(3) 3 μm of PZT was deposited on the insulating film 106 by sputtering, and baked at 700 ° C. for 5 hours to form the piezoelectric layer 107. On the piezoelectric layer 107, Pt / Ti = 3000 / 300Å was formed as an electrode by sputtering and patterned to form the upper electrode 108.
(4) The piezoelectric element 109 was formed by dry etching the piezoelectric layer 107 using C ₄ F ₈ and Cl ₂ . At this time, the Ta ₂ O ₅ layer functioned as an etching stop layer.
(5) After resist patterning, SF ₆ and C ₄ F ₈ are introduced alternately, and ICP (Inductively Coupled Plasma) etching is used to dig Si into the box layer, and an ink pressure chamber 111 is formed below the piezoelectric element portion. Formed.
(6) An ink discharge port 112 having a diameter of 40 μm is formed on another silicon substrate having a thickness of 150 μm by using the ICP method, and the orifice plate 113 is formed.
(7) A film was formed on the above-mentioned parts by sputtering with Au / Ti = 1000/300 mm, and bonded by applying a pressure of 3 MPa at 300 ° C. with a vacuum bonding machine. Thus, the ink jet recording head 114 is completed.

The dimensions of each part of the head were the same as those in Example 1-1. Using this head, a 3 pl droplet at 30 KHz and a print test with a width of 12.5 mm were performed using aqueous ink with a viscosity of 2 cp. A high-quality printed matter with no non-ejection was obtained up to 3 × 10 ¹⁰ times. It was.

As described above, according to the present embodiment, the insulating layer laminated between the piezoelectric film and the lower electrode suppresses the failure due to the electric leakage at the end face portion of the piezoelectric element formed after the piezoelectric element etching. Further, by providing an insulating layer having an etching rate different from that of the piezoelectric material on the lower electrode, the lower electrode is not over-etched, and contamination of the element portion due to scattering of the lower electrode material is suppressed.
[Second Embodiment]
FIG. 6A is a schematic cross-sectional view of the ink jet recording head of this embodiment, and shows a cross section taken along the line AA ′ of FIG. A Si wafer is used as the substrate. An SiO ₂ layer (box layer) 102, a Si single crystal layer (SOI layer) 103 as a vibration plate, a lower electrode 105, an insulating layer 106, a piezoelectric layer 107, and an upper electrode 108 as piezoelectric elements are sequentially formed on a Si substrate 101. Has been.

  The insulating layer 106 is as described in the first embodiment.

  As the piezoelectric layer 107, a piezoelectric body having a perovskite structure mainly composed of lead zirconate titanate, relaxor, or barium titanate is used.

  In the substrate 101, an ink pressure chamber 111 is formed by etching under a diaphragm. Further, an ink jet recording head is formed by joining an orifice plate 113 in which an ink communication portion 115 and an ink discharge port 112 are formed. As the orifice plate 113, a SUS substrate or a Si substrate can be used.

  The structure, material, and manufacturing method of the ink pressure chamber are not limited to those described here as long as the ink that is a liquid can effectively have an ejection force. In addition, an appropriate forming method can be used as a method for forming the electrode material, the insulating film, and the piezoelectric body.

  The diaphragm is formed on a partition wall that partitions the ink pressure chamber and on the partition wall. The insulating layer 106 is also formed on the partition between adjacent piezoelectric elements.

  FIG. 6B is a schematic bird's-eye view of the piezoelectric element portion of the ink jet recording head according to the present invention. Here, the piezoelectric element portion means the lower electrode 105, the piezoelectric layer 107, and the upper electrode 108 corresponding to the ink pressure chamber 111. The width of the upper electrode 108 is narrower than the width of the piezoelectric layer 107, and the width of the lower electrode 105 is wider than the width of the piezoelectric layer 107. The insulating layer 106 is provided between the piezoelectric layer 107 and the lower electrode 105, and electrically connects the lower piezoelectric insulating layer 106 c in the lower portion of the piezoelectric layer 107, the lower electrode 105, and the piezoelectric layer 107. And a non-formation region 106d for contacting the surface. Further, as shown in FIGS. 6A and 6B, an insulating layer 106 is formed on the outer peripheral portion of the piezoelectric element portion, and the lower electrode 105 is covered.

  Further, as shown in FIG. 7, the piezoelectric element portion may have a structure in which the insulating film is covered along the outer edge in the longitudinal direction of the piezoelectric element portion and the periphery in the short side direction is not covered with the insulating film. In this case, compared with the structure shown in FIG. 6B, the lower electrode 105 around the short side direction of the piezoelectric element portion is exposed, so the probability of occurrence of a short between the upper and lower electrodes is slightly increased. However, since the constraint of the piezoelectric element portion by the insulating layer 106 is weakened, the displacement when the same voltage is applied is improved.

  6B and 7, the piezoelectric layer 107 is extended to a portion other than the piezoelectric element portion for an extraction electrode and at least one end of the piezoelectric layer 107 is ink. It extends beyond the area of the ink pressure chamber across one end of the pressure chamber (not shown). By providing an insulating layer 106 between the piezoelectric layer 107 and the lower electrode 105 that exist outside the piezoelectric element portion, it is more than the case where only the insulating layer 106 or only the piezoelectric layer 107 exists between the electrodes. Since the capacitance can be reduced, high-speed driving is possible. In particular, in the case of the present embodiment, the lower electrode 105 and the piezoelectric layer 107 are in electrical contact with each other because the non-formation region 106d is formed. In the configuration in which the electrode and the piezoelectric layer are present via the insulating layer, an electric field is applied to the piezoelectric layer, but the present embodiment in which the lower electrode 105 and the piezoelectric layer 107 are in contact has better performance as a piezoelectric element. .

  FIG. 8 is a longitudinal sectional view of the ink jet recording head according to the present embodiment, and is a schematic view of a BB ′ section of FIG. In FIG. 8, the structure such as the orifice plate is omitted. As shown in FIG. 8, the portions where the piezoelectric layer 107 and the lower electrode 105 other than those on the ink pressure chamber exist are merely for wiring. In the wiring portion, the structure of the upper electrode 108, the piezoelectric layer 107, and the lower electrode 105 becomes a capacitor, and unnecessary capacitance is generated. Therefore, it is desirable that the lower electrode 105 and the piezoelectric layer 107 in this portion be completely cut off by the insulating layer 106. By selecting a material having a dielectric constant lower than that of the piezoelectric layer 107 as the insulating layer 106, the capacitance of this portion can be reduced, and a faster response is possible.

Next, a process example of the ink jet recording head according to the present invention will be described step by step with reference to FIGS. 9A and 9B.
(A) Pt / Ti is formed as the lower electrode 105 on the silicon substrate 101 having the diaphragm layer 103 which is an SOI layer and the oxide film 102 which is a box layer, and an insulating layer 106 is further formed thereon. As the insulating layer, Al ₂ O ₃ , AlN, Si ₃ N ₄ , SiO ₂ , MgO, Ta ₂ O ₅ , SiC, or the like is applicable.
(B) The formed insulating layer 106 is patterned to form a non-formation region 106d.
(C) A thin film mainly composed of lead zirconate titanate or barium titanate is deposited on the patterned insulating layer 106 and fired at 600 to 800 ° C. to form the piezoelectric layer 107. A metal such as Pt / Ti is formed on the piezoelectric layer 107 as the lower electrode 106.
(D) The upper electrode 108 is patterned.
(E) The piezoelectric layer 107 is etched to perform element isolation, and the piezoelectric element 109 is formed. At this time, the insulating layer 106 is used as an etching stop layer by a dry etching method. By using the insulating layer 106 as an etching stop layer, it is possible to prevent the Pt / Ti or the like of the lower electrode 105 from being sputtered and attached to the end face of the piezoelectric element.

The insulating layer 106 where the surface is exposed by dry etching is preferably thinner than the insulating layer 106 c under the piezoelectric layer 107. This is because the restraint of the entire diaphragm becomes smaller as the exposed insulating layer portion becomes thinner.
(F) After resist patterning, the silicon substrate 101 is etched from the side facing the surface on which the piezoelectric element 109 is formed to form an ink pressure chamber 111 below the piezoelectric element 109.
(G) The ink communication part 115 and the ink discharge port 112 are formed on another silicon substrate to form the orifice plate 113.
(H) The aforementioned parts are joined to complete the ink jet recording head 114.
[Example 2-1]
FIG. 6 is a schematic sectional view of an ink jet recording head showing an embodiment according to the present invention. A silicon SOI wafer was used as the substrate. On the Si substrate 101 having a thickness of 200 μm, the SiO 2 layer (box layer) 102 is 1 μm, and the Si single crystal layer (SOI layer) 103 is 5 μm as a vibration plate. A thermal oxide film SiO ₂ layer having a thickness of 300 nm is formed on the SOI layer 103 (not shown). On top of that, Pt 300 nm / Ti 30 nm was formed as the lower electrode 105, 300 nm of SiO ₂ was formed as the insulating layer 106, and a part of the insulating layer 106 was removed by etching to form a non-formation region. Thereafter, a piezoelectric layer 107 of lead zirconate titanate (PZT) 2.7 μm and an upper electrode 108 of Pt / Ti = 300/30 nm are sequentially formed, and the upper electrode 108 and the piezoelectric layer 107 are sequentially etched to form a piezoelectric element. 109 was formed. The thickness of the diaphragm, PZT, electrode, insulating film, etc. raised in this embodiment is only an example, and can be appropriately changed according to the application. In consideration of the displacement inhibition and the function as an etching stop layer, the insulating layer 106 is suitably around 10 nm to 1000 nm when SiO ₂ is used.

  A hole was formed in the substrate 101 by etching to form an ink pressure chamber 111 under the diaphragm. Further, an orifice silicon substrate 113 having an ink communication portion 115 and an ink discharge port 112 was bonded to produce an ink jet recording head.

  The width of the ink pressure chamber was 100 μm, the depth was 3 mm, and the pitch between elements was 220 μm.

Using this head, a 3 pl droplet at 30 KHz and a print test with a width of 12.5 mm were performed using aqueous ink with a viscosity of 2 cp, and a high-quality printed matter without ejection failure was obtained up to 2 × 10 ¹⁰ times. It was.
[Comparative Example 2-1]
A device similar to that of Example 2-1 was prepared except that the insulating layer 106 was not formed. Using this head, a 3 pl droplet at 30 KHz and a printing test at a width of 12.5 mm using aqueous ink with a viscosity of 2 cp. Went. As a result, a short circuit occurred between the upper and lower electrodes at 5 × 10 ⁹ times, resulting in non-ejection.
[Example 2-2]
As shown in FIG. 10, the insulating layer 106 was over-etched, and the insulating layer 106 b in a portion other than under the piezoelectric layer 107 was thinned to 200 nm. Other structures were the same as in Example 2-1. When the deformation of the piezoelectric element portion was measured, the displacement when a voltage of 30 V was applied was 8% larger than that of Example 2-1. In the printing test, a high-quality printed matter having no ejection up to 2 × 10 ¹⁰ times was obtained.
[Example 2-3]
Next, a method of manufacturing the ink jet recording head according to the present invention will be described in order with reference to FIGS. 9A and 9B.
(A) A Pt / Ti = 300/30 nm film was formed as a lower electrode 105 on a silicon substrate 101 having a thickness of 200 μm with a box layer 102, which is a 1 μm SiO ₂ layer, and a 5 μm SOI layer 103, by sputtering. Furthermore, 300 nm of Ta ₂ O ₅ was deposited thereon as the insulating layer 106 by sputtering.
(B) A part of the insulating layer 106 formed next was removed by etching to form a non-formation region 109.
(C) 3 μm of PZT was deposited by sputtering on the insulating layer 106 in which the non-formation region 109 was formed, and baked at 700 ° C. for 5 hours in an oxygen atmosphere to obtain the piezoelectric layer 107. Further, Pt / Ti = 300/30 nm was deposited on the piezoelectric layer as an electrode by sputtering.
(D) The upper electrode 108 was formed by patterning the formed Pt / Ti = 300/30 nm.
(E) The piezoelectric layer 109 was dry-etched using C ₄ F ₈ and Cl ₂ as etching gases to form the piezoelectric element 109. At this time, the Ta ₂ O ₅ layer functioned as an etching stop layer.
(F) After resist patterning, the silicon substrate 101 was etched using the box layer 102 as a stop etching layer from the surface facing the surface on which the piezoelectric element was formed. As the etching method, a method capable of vertical deep drilling is preferable. In this embodiment, etching is performed using a so-called Bosch process using ICP (Inductively Coupled Plasma) capable of generating high-density plasma as a plasma source and using SF ₆ and C ₄ F ₈ as etching gases. After etching until the box layer 102 was exposed, the exposed box layer was removed using buffered hydrofluoric acid to form an ink pressure chamber 111.
(G) On another silicon substrate having a thickness of 150 μm, the ink communication portion 115 and the ink discharge port 112 having a diameter of 30 μm are formed using the ICP method, and the orifice plate 113 is formed.
(H) A film was formed on the above-mentioned parts by the sputtering method Au / Ti = 100/30 nm, and bonded by applying a pressure of 3 MPa at 300 ° C. with a vacuum bonding machine. Thus, the ink jet recording head is completed.

The dimensions of each part of the head were the same as in Example 2-1. Using this head, a 3 pl droplet at 30 KHz and a print test with a width of 12.5 mm were performed using aqueous ink with a viscosity of 2 cp. A high-quality printed matter with no ejection up to 3 × 10 ¹⁰ times was obtained. Obtained.

  As described above, according to the present embodiment, by providing the insulating layer on the lower electrode so that a part thereof extends to the lower portion of the piezoelectric body, the lower electrode is exposed and sputtered when the piezoelectric body is etched. In addition, contamination of the element portion due to scattering of the lower electrode material is suppressed. In addition, by interposing an insulator having a dielectric constant lower than that of the piezoelectric body between the piezoelectric body and the lower electrode, the capacitance of the element can be reduced, and the response to the drive waveform can be made faster. Precise discharge control becomes possible.

1 is a cross-sectional view of an ink jet recording head according to a first embodiment of the present invention. It is sectional drawing of the other example of the inkjet recording head by the 1st Embodiment of this invention. 3 is a flow chart of manufacturing the ink jet recording head according to the first embodiment of the present invention. 3 is a flow chart of manufacturing the ink jet recording head according to the first embodiment of the present invention. It is sectional drawing of the inkjet recording head of a comparative example. It is sectional drawing of the inkjet recording head by Example 1-2 of this invention. It is sectional drawing and the top view of the inkjet recording head by the 2nd Embodiment of this invention. It is a top view of the other example of the inkjet recording head by the 2nd Embodiment of this invention. FIG. 5 is a longitudinal sectional view of an ink jet recording head according to a second embodiment of the present invention. It is a manufacturing flow of the inkjet recording head in the 2nd Embodiment of this invention. It is a manufacturing flow of the inkjet recording head in the 2nd Embodiment of this invention. It is sectional drawing of the inkjet recording head in Example 2-2 of this invention.

Explanation of symbols

105 Lower Electrode 106 Insulating Film 107 Piezoelectric Layer 108 Upper Electrode 109 Piezoelectric Element 111 Ink Pressure Chamber 112 Ink Ejection Port 114 Inkjet Recording Head

Claims (6)

A plurality of pressure chambers that communicate with a discharge port that discharges the liquid and pressurizes the liquid; a lower electrode that is provided corresponding to each of the plurality of pressure chambers and stacked in order from the pressure chamber side; and a piezoelectric body A plurality of piezoelectric elements having a layer and an upper electrode, and a liquid ejection head in which the lower electrode is provided up to a region corresponding to between the plurality of pressure chambers,
An insulating layer that covers all of the lower electrode provided in a corresponding region between at least the plurality of pressure chambers is formed ;
The thickness of the portion provided in the region corresponding to the space between the plurality of pressure chambers in the insulator layer is provided in the region corresponding to the piezoelectric layer in the insulator layer. A liquid discharge head characterized by being thinner than the thickness of the portion .   At least one end of the piezoelectric layer extends outside a region corresponding to the pressure chamber, the piezoelectric layer is wider than the upper electrode and narrower than the lower electrode, and the insulator layer is at least the piezoelectric element. A portion where the insulator layer is not formed is provided to electrically contact the lower electrode and the piezoelectric layer, wherein the insulating layer is not formed. The liquid discharge head described.   The liquid ejection head according to claim 2, wherein the insulator layer is formed along at least the outer periphery of the piezoelectric element.   4. The liquid ejection head according to claim 1, wherein the insulating layer is thinner than the piezoelectric layer. 5. A plurality of pressure chambers that communicate with a discharge port that discharges the liquid and pressurizes the liquid; a lower electrode that is provided corresponding to each of the plurality of pressure chambers and stacked in order from the pressure chamber side; and a piezoelectric body includes a plurality of piezoelectric element having a layer and the upper electrode, wherein the plurality of the lower electrode to the corresponding region between the adjacent pressure chambers is provided, an insulating the lower electrode provided in at least the region A method of manufacturing a liquid ejection head that is entirely covered by a body layer,
Forming an insulator layer on the lower electrode;
Forming a material layer of the piezoelectric layer on the insulator layer;
Of the material layer of the piezoelectric layer, a portion corresponding to the space between the plurality of pressure chambers is etched to form the plurality of piezoelectric layers, and the plurality of pressures of the insulator layer A portion provided in a region corresponding to between the chambers is exposed, and the thickness of the portion is made smaller than a thickness of a portion of the insulator layer provided in a region corresponding to the piezoelectric layer. Process,
A method for manufacturing a liquid discharge head, comprising: The method of manufacturing a liquid ejection head according to claim 5 , wherein the etching is dry etching, and the lower electrode contains Pt.

Images