JP2005144918A - Liquid discharging head and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a configuration of an inkjet head which prevents a vibrating plate displacement amount decrease even when nozzles are formed by a high density, and prevents a compliance increase of partition walls for partitioning each pressure chamber, and to provide its manufacturing method. <P>SOLUTION: The inkjet head consists of driving elements which expand and contract by an application signal, a vibrating plate which constitutes a part of each pressure generation chamber, partition walls for separating the pressure generation chamber from each pressure generation chamber, an ink feeding passage, an ink feeding liquid chamber, and the nozzles. The inkjet head jets ink droplets from the nozzles by displacing the vibrating plate through deformation of the driving elements, and enhancing an ink pressure in the pressure generation chambers corresponding to the driving elements. The vibrating plate is composed of a plurality of different materials in an in-plane direction of a vibrating plate principal plane. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid discharge head that discharges a desired liquid by mechanical energy generated from a drive element that expands and contracts by an applied signal, a method for manufacturing the same, and a recording apparatus using the head.

  Conventionally, liquid ejection devices have been applied in various fields such as microfabrication, experimental analysis, and image formation. In particular, in an ink jet recording method, ink droplets are ejected and deposited on a recording medium to form an image, thereby enabling high speed recording, high recording quality, and low noise. Have. Furthermore, this method has many excellent advantages such as easy color image recording, recording on plain paper and the like, and further facilitating miniaturization of the apparatus. A recording apparatus using such an ink jet recording method is generally provided with an ejection port for ejecting ink as flying ink droplets, an ink channel communicating with the ejection port, and a part of the ink channel, There is provided a recording head having energy generating means for giving ejection energy for ejection to the ink in the ink flow path.

  As a typical example of an ink jet head that performs recording by ejecting ink, as disclosed in Patent Document 1, the volume of an ink chamber is changed by vibrating a piezo element, and ink is sucked at a first timing. In the second timing, pressure is applied to the ink to make it fly as a droplet onto the recording paper, and as shown in Patent Document 2, a heating element is built in an extremely thin nozzle forming member, and the nozzle is generated by heat energy. There have been proposed ones in which bubbles are instantaneously generated in the forming member and ink is ejected by the expansion force of the bubbles.

  An ink jet head using a piezo element has the advantage that the ink selection range can be expanded because the ink droplet size can be varied by voltage displacement and heat is not applied to the ink. Under such circumstances, due to the recent demand for high-definition printing, precision fine processing and complicated desired shapes accompanying the increase in the number of nozzles have become necessary.

  Under such circumstances, in Patent Document 3 (FIG. 10), when the pressure generating chamber 2 is formed, the side wall of the diaphragm 1 support portion on the pressure generating chamber side is obtained by combining anisotropic etching and dry etching of the Si single crystal substrate. Discloses a structure having a taper 13. By doing so, the compliance of the diaphragm 1 can be increased without increasing the compliance of the partition walls 5. Therefore, a large amount of ink can be ejected at a high speed while taking a large deformation amount of the piezoelectric element.

Patent Document 4 (FIG. 11) discloses an ink jet head that can select whether or not the part 17 of the pressure generating chamber 2 side diaphragm 16 is etched and can adjust the compliance (displacement amount) of the diaphragm. ing.
U.S. Pat. No. 3,946,398 JP 54-161935 A JP-A-10-286960 JP-A-11-227190

  However, in the manufacturing method disclosed in Patent Document 3, the etching method is switched when the taper 13 is formed, and a side progression pattern (taper) is formed using dry etching. Therefore, it is clearly difficult to form an accurate taper cut amount without depending on the substrate area and position.

  Further, in the manufacturing method disclosed in Patent Document 4, the cutout amount of the diaphragm support portion is controlled by wet etching using an etching stop layer. Similarly to the above, it is difficult to form an accurate taper cut amount without depending on area and position. In addition, since the tapered portion 17 has a rectangular shape and is substantially constricted, it is difficult to eliminate bubbles generated in the ink once entering the tapered portion.

  The present invention has been made in view of the above problems. An object of the present invention is to provide an ink jet head that is less likely to cause a decrease in the displacement amount of the diaphragm even when the nozzle density is increased, and less likely to increase the compliance of the partition walls that separate the pressure chambers. To provide a recording apparatus capable of high-definition and high-speed printing.

  The first of the present invention is a drive element that expands and contracts by an applied signal, a diaphragm that forms part of each pressure generating chamber, a partition that separates the pressure generating chamber from each pressure generating chamber, an ink supply path, and an ink supply liquid chamber And an ink jet head configured to eject ink droplets from the nozzle by displacing the diaphragm by deformation of the driving element and increasing ink pressure in the pressure generating chamber corresponding to the driving element. The diaphragm is made of a plurality of different materials in the in-plane direction of the diaphragm main surface.

In the present invention, the diaphragm is formed of a part of single crystal silicon and a metal oxide, and a part of the single crystal silicon doped with at least one of B, Au, Pt, C, Ti and a metal The oxide is used, is formed using the (100) plane of single crystal Si, and the metal oxide material formed together with the single crystal Si is at least one of SiO _x , ZrSiO _x , and ZrO _x . In the inkjet head, the pressure chamber has a tapered shape so that the pressure chamber becomes narrower in the vertical direction from the diaphragm toward the nozzle, and the minimum width of the partition located between adjacent pressure generation chambers is It is included as a preferable aspect that it is 20 micrometers or less.

  According to the present invention, the compliance of the diaphragm can be arbitrarily adjusted, and since the diaphragm is made of a part of single crystal silicon, problems such as poor adhesion and peeling of the diaphragm do not occur. Further, by adopting such a shape that the shape of the pressure chamber becomes narrower from the diaphragm toward the nozzle in the vertical direction, it is possible to increase the diaphragm displacement without increasing the compliance of the partition wall.

A second aspect of the present invention is the above-described method for manufacturing an inkjet head,
1) A step of doping ions into single crystal Si.

  2) A step of etching the doping layer into a plurality of lines intersecting the (110) and (011) orientations of single crystal Si.

  3) A step of etching Si located under the doping layer using an alkaline aqueous solution.

  4) A step of etching from the surface opposite to the doping layer to form an ink communication port and a common liquid chamber.

  5) A step of forming a SiOx layer by thermal oxidation treatment.

  6) A step of forming a metal oxide film from the doping layer side.

  A method for manufacturing an ink-jet head, comprising:

  In the present invention, in the step of etching the doping layer in a line shape, the etching line width is 4 μm or less, the alkaline aqueous solution for etching Si under the doping layer is either KOH or EDP, doping The method of forming the ink communication port and the common liquid chamber from the side opposite to the layer is ICP-RIE, or the method of forming the ink communication port from the side opposite to the doping layer is ICP-RIE. The method of forming the liquid chamber is anisotropic etching using an alkaline aqueous solution, the method of forming a metal oxide film from the doping layer side uses at least one of LPCVD and PECVD, and from the doping layer side After film formation, a flattening process is performed, the flattening process is an etch back method, and ink is discharged. Separately forming a nozzle for those comprising a preferred embodiment to be a formed by pasted so as to communicate with the communicating port communicating with the pressure chamber.

  According to the present invention, since the pressure chamber can be wet-etched from the diaphragm side using an alkaline aqueous solution, the tapered shape is such that the shape of the pressure chamber becomes narrower in the vertical direction from the diaphragm toward the nozzle. Can be easily and accurately formed.

  A third aspect of the present invention is the above-described ink jet head and a method for manufacturing the same, wherein the driving element of the diaphragm is formed of a thin film having a thickness of 10 μm or less.

  In the present invention, it is preferable that the driving element of the diaphragm is formed of a piezoelectric thin film having a thickness of 10 μm or less.

  According to the present invention, by using a thin film as a driving element, high-precision processing by photolithography used in a semiconductor manufacturing method can be performed regardless of conventional machining, and ink jet with good response to diaphragm displacement It becomes possible to provide a head.

  According to a fourth aspect of the present invention, the inkjet head includes a plurality of drive elements, a diaphragm, a pressure generation chamber, and a nozzle, and includes means for supplying an electric signal for expanding and contracting each drive element. Device.

  According to the present invention, it is possible to provide an ink jet recording apparatus in which each nozzle can obtain desired ink ejection with respect to an arbitrary waveform, and can perform high resolution and high speed printing.

  The compliance of the diaphragm can be arbitrarily adjusted, and the diaphragm is composed of a part of single crystal silicon, so that problems such as poor adhesion and peeling of the diaphragm do not occur. Further, by adopting such a shape that the shape of the pressure chamber becomes narrower from the diaphragm toward the nozzle in the vertical direction, it is possible to increase the diaphragm displacement without increasing the compliance of the partition wall. In addition, since the pressure chamber can be wet etched from the diaphragm side using an alkaline aqueous solution, it is easy to taper the pressure chamber shape so that it narrows in the vertical direction from the diaphragm toward the nozzle. In addition, it can be formed with high accuracy.

By using a thin film as a driving element, an inkjet head that can perform high-precision processing by photolithography used in a semiconductor manufacturing method, and has good response to vibration of a vibration plate, regardless of conventional machining. It becomes possible. High definition,
It is possible to provide a recording apparatus capable of high-speed printing.

(Configuration of inkjet head)
Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are schematic cross-sectional views of the main part of an ink jet head according to the present invention. FIG. 1 shows a cross-sectional view taken along the line AA ′ of FIG. As shown in FIG. 1, the main part of the ink jet head is formed by integrally forming a pressure chamber 2 and a diaphragm 1 and a drive element 7 on the diaphragm. A nozzle plate 4 having nozzles 9 is bonded to the other surface of the substrate on which the pressure chamber is formed.

  Each pressure chamber is formed in parallel via a partition wall, and each pressure chamber communicates with the ink common liquid chamber via the restrictor 11 so that ink can be filled from the common liquid chamber into each pressure chamber. Become.

  The diaphragm causes the volume change of the pressure chamber by bending due to the volume change generated in the drive element. In order to apply a signal to the drive element provided on the diaphragm, a lower electrode 6 is formed below the drive element. The lower electrode may be provided on the entire surface of the diaphragm as a common electrode, or may be provided only on the drive element portion and other necessary portions.

  The ejection principle when the drive element is formed of a piezoelectric body is that the volume of the piezoelectric element does not change when no voltage is applied between the lower electrode and the upper electrode. Therefore, the pressure in the pressure generating chamber corresponding to the piezoelectric element to which no voltage is applied does not change, and ink is not ejected from the nozzle. On the other hand, when a voltage that causes a volume change in the piezoelectric element is applied between the lower electrode and the upper electrode of the piezoelectric element, the volume change occurs in the piezoelectric element, and the piezoelectric element to which the voltage is applied is applied. The attached diaphragm is greatly bent, the pressure in the corresponding pressure generation chamber is instantaneously increased, and the liquid is discharged from the nozzle.

In the embodiment of the present invention, the diaphragm is made of different materials in the in-plane direction of the diaphragm main surface. As a result, the Young's modulus at the displaceable portion of the diaphragm can be arbitrarily adjusted. Specifically, as will be described later, the diaphragm is mainly formed by doping ions into a part of a silicon substrate so as to be insoluble in an alkaline aqueous solution. The Young's modulus of the diaphragm can be changed by changing the ion species of doping. The ion species is preferably selected from at least one of B, Au, Pt, C, and Ti, and among these, B is preferably used. Further, a metal oxide is used as the material provided in the gap between the insoluble portions of the alkaline aqueous solution by the above-described ion doping, but the properties of the diaphragm can be adjusted also by this material. The metal oxide used _herein, is preferably used easily formable SiO _x by SiO x, ZrSiO _x, be composed is selected from at least one of ZrO _x Desirably, the silicon substrate is thermally oxidized . Further, ZrSiO _x and ZrO _x may be used at the same time for stress adjustment when the diaphragm is formed.

  As described above, in the present invention, since a part of the silicon substrate is used as the vibration plate, it is not necessary to use a separate vibration plate for forming the vibration plate, and it is naturally necessary to bond them by bonding or various bonding methods. There is no. For this reason, there is no fear of manufacturing problems such as poor adhesion and peeling of the diaphragm. In addition, when various bonding methods such as bonding and various anodic bonding are used, it is difficult to reduce the partition between the pressure generating chambers because the bonding surface needs a certain area. However, in the present invention, because of the accuracy of etching with an alkaline aqueous solution, that is, the accuracy of anisotropic etching of silicon, the minimum width of the partition walls should be 20 μm or less when using the above-described adhesion and various joining methods. Is also possible.

  In the present invention, the pressure generating chamber has a tapered shape so as to become narrower in the vertical direction from the diaphragm toward the nozzle. In general, when the density of the nozzle is increased, the diaphragm width becomes narrower, and it becomes difficult to obtain a deformation volume due to diaphragm deformation. Here, the deformation volume V of the diaphragm due to the bending deformation of the piezoelectric element has the following relation when the width of the diaphragm is w, the thickness is t, and the length L of the pressure chamber is as follows (FIG. 8).

V ｗ w ³・ 1 / t ²・ L ・ ・ ・ ・ Formula 1
It can be seen from Equation 1 that the diaphragm width contributes the most as a structural value in the deformation volume of the diaphragm. For this reason, it is desirable to make the diaphragm width as large as possible in order not to reduce the deformation volume even when the density of the head is increased.

  As a result, it is necessary to increase the diaphragm width as shown in FIG.

  Next, the depth direction (depth d) of the partition wall needs to be designed in consideration of the refill characteristics. The refill cycle of the ink jet head configuration as described this time is described by a coupled vibration of meniscus compliance and pressure chamber ink inertance in an equivalent circuit expression.

  The ink inertance is proportional to ρ · 1 / S · L, where ρ is the ink density, S is the cross-sectional area of the flow path, and L is the length of the pressure chamber. In order to prevent the refill cycle from being lowered, it is necessary to reduce the ink inertance L. This corresponds to increasing the pressure chamber cross-sectional area, and is directly related to the pressure chamber depth (depth d).

  In addition, the depth and thickness of the partition walls must be designed in consideration of partition compliance. In general, as the nozzle density increases, the partition wall becomes thinner and the partition compliance increases. For this reason, a crosstalk phenomenon between adjacent pressure chambers and a decrease in the coupling frequency between the actuator and ink lead to a decrease in the ejected droplet speed. Here, the compliance C (deformation amount / unit pressure) of the partition wall has the following relationship with the structure value (thickness t, depth w, length L) of the partition wall (FIG. 4).

C ∝ w ⁵・ 1 / t ³・ L ・ ・ ・ ・ Formula 2
The structure values (thickness t, depth w) of the partition walls greatly contribute to the compliance amount. Therefore, it is necessary to reduce the partition compliance in order to prevent a decrease in the discharge droplet speed. That is, it is desirable to reduce the depth w of the pressure generating chamber and reduce the thickness t of the partition wall.

  In the case of a high-density head, both the pressure generation chamber width and the partition wall thickness are narrow and thin, and the depth becomes shallow due to the problem of securing rigidity. As a result, the head performance (ejection speed, refill cycle) and production yield decrease. However, with the above-described head structure, the head performance is not greatly deteriorated, and the production yield can be improved.

  In the present invention, it is desirable to use anisotropic etching of an Si (100) single crystal substrate with an alkaline aqueous solution in order to form an accurate taper when the diaphragm diaphragm and the pressure generating chamber are formed. By using anisotropic etching of silicon, a shape depending on the crystal orientation can be produced. For this reason, it becomes a shape along the crystal orientation <110> also in the pressure chamber length direction and the cross-sectional direction, and the tapered portion is formed by the {111} plane. As a result, only the mask pattern affects the accuracy, and a shape with a necessary and sufficient accuracy can be obtained.

(Inkjet head manufacturing method)
Next, the manufacturing method of the inkjet head of this invention is explained in full detail using FIGS. First, a silicon wafer is prepared as a substrate. The thickness of the silicon wafer is determined in consideration of the depth of the pressure chamber, the length of the communication port, and the volume of the ink common liquid chamber, but it is desirable to use a substrate having a thickness of about 200 to 300 μm. The plane orientation of the single crystal silicon substrate is preferably (100) in order to form a tapered shape such that the pressure chamber becomes narrower in the vertical direction from the diaphragm toward the nozzle.

The silicon wafer is subjected to ion doping at a high concentration. As an ion species used for doping, at least one of B, Au, Pt, C, and Ti is used. Depending on the ion species and concentration of doping, the etching rate for etching with an aqueous alkali solution to be performed later and the Young's modulus of the diaphragm when used as a diaphragm are affected. The doping of B is preferably used from the viewpoint of insolubility with respect to an aqueous alkali solution. The doping concentration is desirably 5 × 10 ¹⁹ cm ⁻³ or more.

  Next, etching is performed on the line so as to penetrate the ion doping layer. Using a method such as a spinner method or a spray method, a resist having a uniform thickness is applied, exposed and developed, and a pattern on a line is formed in the upper portion of the pressure chamber as shown in FIG. Thereafter, dry etching is performed by reactive ion etching so as to penetrate the ion doping layer. At this time, the width of the etched line-shaped pattern is preferably 4 μm or less, more preferably 2.5 μm or less, so that the diaphragm can be easily formed in the subsequent film forming process. As shown in FIG. 4, the line pattern is provided so as to intersect with the <110> and <011> directions of the silicon substrate. Although it may be provided obliquely at the top of the pressure generating chamber as shown in FIG. 4 (b), it is formed by two straight lines intersecting the <110> and <011> directions as shown in FIG. 4 (a). It may be arranged above the pressure generating chamber. If the ion doping layer is etched in such a line shape, the etching of the silicon substrate proceeds in the direction indicated by the arrow in FIG. 4 below the ion doping layer with respect to the alkaline aqueous solution, and the etching rate becomes extremely high. Etching can be performed to leave a slow (111) plane. As the aqueous alkali solution used at this time, an aqueous KOH solution, TMAH (tetramethylammonium hydroxide), or EDP (ethylenediamine / pyrocatechol) is preferably used. Among them, a KOH aqueous solution and EDP are preferable because the etching rate of (110) with respect to (111) is large and the side etching in the (111) direction from the mask pattern is small, so that the shape control of the partition wall is easy. By performing wet etching with an alkaline aqueous solution in this way, a part of the ion doping layer is left in a beam shape as shown in FIG. 7B, and the pressure generation chamber is formed from the ion doping surface as shown in FIG. A tapered shape can be formed so as to become narrower in the vertical direction toward the nozzle.

Next, a communication port and a common liquid chamber are formed. As shown in FIG. 7C, the communication port is preferably formed vertically toward the diaphragm, and is formed using anisotropic dry etching. Anisotropic dry etching using SF6 (sulfur hexafluoride) gas or an organic gas containing fluorine element or or a mixed gas of an organic substance containing SF ₆ and elemental fluorine, as an etching gas, the purpose communication port after etching The reaction pressure and the mixing ratio of the mixed gas are appropriately adjusted so as to obtain the shape, and the process is performed at room temperature until the communication port penetrates the pressure generation chamber. Similarly, the ink common liquid chamber is dry-etched until it penetrates through the pressure generating chamber and the throttle portion. Since the area of the narrowed portion becomes wider as the dry etching progresses, it is desirable that the reaction pressure, the mixing ratio of the mixed gas, the etching time, and the like are precisely controlled. The communication port and the ink common liquid chamber may be formed simultaneously.

  The ink common liquid chamber may be formed by anisotropic wet etching of silicon with an alkaline aqueous solution. By using anisotropic wet etching, it is possible to perform batch processing of a plurality of sheets, so that the manufacturing method is excellent in mass productivity.

Next, SiO _x is formed by a thermal oxidation method. As a result, SiO _x having a film thickness of about 1.0 to 2.0 μm is formed on the entire surface of the silicon substrate, so that SiO _x is also formed on the beam in the upper part of the pressure generation chamber made of the ion doping layer, and finally the diaphragm and A part of the part is formed. Furthermore, as the inkjet head, the wall surface of the communication port and the ink common liquid chamber is covered with the SiO _x film, so that even when an alkaline liquid is discharged, the wall surface is not eroded and there is a problem in durability. There will be no inkjet head. Subsequently, by further depositing SiO _x by the LPCVD method, the upper surface of the pressure generating chamber is completely sealed, and a diaphragm is formed as shown in FIG.

At this time, the film forming method is not limited to the LPCVD method, and any film forming method having a high deposition rate may be used. Other than the LPCVD method, the PECVD method can be suitably used. Even if the material for forming the film is other than SiO _x , it is sufficient if the pressure generating chamber can be completely sealed. From the viewpoint of stress, ZrSiO _x and ZrO _x are desirable. A plurality of materials may be used from these materials.

The communication port and the ink common liquid chamber may be formed after the diaphragm is formed by thermal oxidation or film formation. In this case, the SiO _x film formed by the thermal oxidation method can function as an etch stop layer in both anisotropic dry etching and anisotropic wet etching of the ink common liquid chamber using an alkaline aqueous solution.

Further, when the upper surface of the vibration plate after the metal oxide film is formed is not flat, a flattening process may be performed. For example, the above-described LPCVD SiO _x film may be formed thick and a part of the surface may be removed later by etching, or an etch-back technique may be used. In the etch back, a resist is applied to the surface of the vibration plate to be flattened, and etching is performed under the condition that the constituent materials of the vibration plate, that is, the SiO _x and the resist etching rate are equal. At this time, in the case of SiOx as the etching gas, a mixed gas of CF ₄ and O _{2 or} the like is used, and the etching rate of SiO _x and the resist is adjusted by appropriately adjusting the mixing ratio. Further, if necessary, it may be added H _2.

  Next, the lower electrode 6 is formed as shown in FIG. A conductive material is used for the lower electrode. For example, platinum, iridium, palladium, an alloy of iridium and platinum, a laminated film of iridium and palladium, or the like can be used. The lower electrode may be provided on the entire surface of the diaphragm as a common electrode, or may be provided only on a portion where the drive element is formed or other necessary portions.

A drive element 7 shown in FIG. 8E is formed on the lower electrode. As the driving element, a piezoelectric body is desirable, and a ferroelectric ceramic exhibiting piezoelectric characteristics is preferably used. Examples of the ferroelectric ceramic include lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT, lead zirconate (PbZrO ₃ ), lead lanthanum titanate ((Pb, La) TiO ₃ ), lead lanthanum zirconate ((Pb, La) (Zr, Ti) O ₃ ): PLZT) or lead zirconate titanate magnesium niobate (Pb (Mg _1/3 Nb _2/3 ) _{0. 1} (Zr, Ti) _0.9 O ₃ ) or the like can be used.

  A sol-gel method, a sputtering method, an MOCVD method, or the like is used to form the piezoelectric body. If the thickness of the piezoelectric layer is too thick, the manufacturing process becomes long and the cost becomes high, or a high driving voltage is required. If the thickness is too thin, the thickness cannot be formed uniformly, and the characteristics of the piezoelectric elements separated after etching vary. Therefore, the thickness of the piezoelectric layer is preferably about 0.5 μm to 10 μm. More desirably, when the thickness is about 0.5 μm to 2 μm, a large amount of displacement due to the balance with the vibration plate can be obtained, so that efficient discharge is possible.

  The upper electrode is an electrode for applying a voltage to the piezoelectric body. The upper electrode is formed of a material having conductivity similar to the lower electrode, such as platinum, by sputtering or the like. The piezoelectric body and the upper electrode are masked so as to match the shape of each pressure chamber, and the periphery is etched to pattern the piezoelectric body and the upper electrode. That is, a resist is applied, exposed and developed, and a resist is formed on the upper electrode. By applying ion milling, dry etching or the like to this, an unnecessary layer structure portion is removed.

  After the lower electrode, the piezoelectric body, and the upper electrode are formed on the diaphragm, sintering is performed according to the piezoelectric material. When PZT is formed by sputtering as a piezoelectric body, the characteristics of the piezoelectric body are improved by sintering at 700 ° C. in an oxygen atmosphere.

  Finally, the nozzle plate is attached. As the metal material constituting the nozzle plate, nickel, duralumin, stainless steel or the like can be used, and the nozzle is formed by machining, electric discharge machining, etching or the like. If necessary, a water repellent may be applied to the surface of the nozzle. The nozzles are aligned and bonded so that each nozzle is aligned with each communication port. As an adhesive used for bonding, for example, an epoxy resin or the like is used.

  FIG. 6 shows a schematic view of the shape of the pressure generating chamber, the communication port, the ink common liquid chamber, and the nozzle formed as described above. The pressure generation chamber is formed so as to become narrower toward the nozzle, and a communication port leading to the nozzle is formed on one side in the longitudinal direction. In addition, an ink common liquid chamber is formed on the other side in the longitudinal direction through a diaphragm.

  In the above manufacturing process, the diaphragm is formed of a part of a silicon substrate and a metal oxide, and a thin film material, that is, a thin film piezoelectric body is used as a driving element. Ink jet heads can be formed with high accuracy because of high-precision processing using photolithography used in semiconductor manufacturing methods, regardless of machining.

  Specific examples are shown below, but the dimensions, shapes, materials, drive conditions, etc. of the drive element, diaphragm, pressure generation chamber, communication port, ink common liquid chamber, nozzle, etc. are examples, and any design items It can be changed to.

(Example)
Hereinafter, the present invention will be described in more detail with reference to examples.

FIG. 12 is a cross-sectional view in the nozzle row direction of the ink jet head according to the present invention. As the substrate, a (100) -oriented silicon single crystal substrate having a thickness of 200 μm was used. First, in order to form an alkali-insoluble layer, B was doped. A silicon substrate was fixed in a quartz tube with a quartz holder, N2 was used as a carrier gas, and steam bubbling BBr3 was introduced into the quartz tube together with O2, and the treatment was performed at 1100 ° C. for a predetermined time. At this time, the B ion concentration was set to 7 × 10 ¹⁹ cm ⁻³ . Next, a plurality of line patterns as shown in FIG. 5 were formed by exposing and developing the resist. At this time, the line width of each line was set to 2.5 μm. The silicon substrate on which the resist pattern was formed was etched by reactive ion etching so that the silicon substrate penetrates the B doping layer to a depth of 2 μm.

  Next, a pressure generation chamber is formed by anisotropic etching with an alkaline aqueous solution. As the alkaline aqueous solution, a KOH aqueous solution having a concentration of 20% by weight was used, and the treatment was performed at 80 ° C.

  Next, patterning is performed from the opposite side of the substrate to form a mask pattern for the communication port and the ink common liquid chamber. Using an ICP-RIE apparatus, etching was performed in a vertical direction using a gas containing SF6 as a main component until penetrating the pressure generation chamber. Thereby, the communication port and the ink common liquid chamber are formed on the back surface of the substrate.

Thereafter, the silicon substrate is subjected to a thermal oxidation treatment at 1100 ° C. for 4 hours in an oxygen and water vapor atmosphere to form a 1 μm thick SiO _x film on the entire surface of the silicon substrate. Further, a SiO _x film is formed by LPCVD, and the opening in which the pressure generation chamber is formed is completely sealed, thereby forming a vibration plate made of a part of the silicon substrate and SiO _x .

For the formation of the piezoelectric element, Pt is formed as a lower electrode by sputtering with a thickness of 150 nm, and then a Pb (Zr _0.52 Ti _0.48 ) O ₃ film is formed as a piezoelectric body with a thickness of 1 μm and Pt as an upper electrode. Is formed to a shape corresponding to each pressure generating chamber. Finally, firing is performed at 700 ° C. in an oxygen atmosphere.

  On the surface opposite to the surface on which the piezoelectric body is formed, a 50 μm thick stainless steel nozzle plate that has been machined to have a nozzle diameter of 20 μmφ and a hole diameter of the portion in contact with the ink communication port of 50 μmφ is used as an adhesive. Adhere using. Finally, in order to drive the member for supplying ink and each piezoelectric element, a flexible cable for transmitting an electric signal was joined.

  The manufactured ink jet head was observed as follows for the ink ejection. First, without supplying ink, the vibration plate displacement (drive element) of the pressure chamber was observed with a laser Doppler displacement meter with respect to the head. As an electrical signal, when a rectangular pulse with a rectangular wave voltage of 30 V was applied, a displacement amount of about 200 nm was confirmed at the center of the diaphragm.

  Next, ink was supplied to the pressure generating chamber, and after confirming the inflow of the supplied ink from the tip nozzle side, a drive waveform was applied and liquid ejection was attempted. At that time, the ejection state of the head from the external nozzle side was observed with a CCD microscope, the vibration plate displacement of the adjacent pressure chamber was observed with a laser Doppler displacement meter, and the meniscus surface of the adjacent nozzle was observed.

  The driving condition of the piezoelectric element of the ejection head was an electric signal composed of a rectangular pulse with a rectangular wave voltage of 30 V and a frequency of 10 kHz, and the situation was observed using a pulse light source and a microscope. That is, the discharge state and the vibration displacement and meniscus displacement in the nozzle adjacent to the driven nozzle were observed while emitting pulsed light in synchronization with the driving pulse for driving the piezoelectric body and with a predetermined delay time. .

  From the head, stable droplet flight of 10 m / s, about 8 pl was confirmed. Further, by ensuring the rigidity of the partition walls, no significant crosstalk was observed in the adjacent heads. Furthermore, the refill cycle was confirmed by measuring the application cycle of the drive waveform and the discharge speed. As the refill cycle, 10 KHz or more could be secured, and no significant refill deterioration was observed.

By forming the diaphragm in the same manner as in Example 1 until the pressure generation chamber is formed by anisotropic etching, the diaphragm is formed first. The silicon substrate is subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an oxygen and water vapor atmosphere to form a 1 μm thick SiO _x film on the entire surface of the silicon substrate. Further, a SiO _x film was formed by LPCVD, and the opening formed with the pressure generation chamber was completely sealed, thereby forming a diaphragm made of a silicon substrate and SiO _x .

Next, using an ICP-RIE apparatus from the back surface, etching was performed in a direction perpendicular to the pressure generation chamber using a gas mainly composed of SF ₆ to form a communication port and an ink common liquid chamber. At this time, since the formed SiO _x film can function as an etch stop layer by thermal oxidation, the shape can be controlled more precisely. Next, in order to remove this SiO _x layer, buffered hydrofluoric acid etching was performed.

  Formation of the piezoelectric element, bonding of the nozzle plate, and joining of the member for supplying ink and the flexible cable were performed in the same manner as in Example 1 to complete the ink jet head.

  As a result of the same evaluation as in Example 1, it was possible to confirm stable droplet flight of about 10 m / s and about 8 pl from the head. Further, by ensuring the rigidity of the partition walls, no significant crosstalk was observed in the adjacent heads. Furthermore, the refill cycle was confirmed by measuring the application cycle of the drive waveform and the discharge speed. As the refill cycle, 10 KHz or more could be secured, and no significant refill deterioration was observed.

Up to the thermal oxidation treatment step, the same process as in Example 1 was performed, and then ZrO _x was formed by sputtering, and the opening in which the pressure generation chamber was formed was completely sealed. A diaphragm made of SiO _x and ZrO _x is formed.

  Formation of the piezoelectric element, bonding of the nozzle plate, and joining of the member for supplying ink and the flexible cable were performed in the same manner as in Example 1 to complete the ink jet head.

  As a result of the same evaluation as in Example 1, stable droplet flight of about 9 m / s and about 8 pl was confirmed from the head. Further, by ensuring the rigidity of the partition walls, no significant crosstalk was observed in the adjacent heads. Furthermore, the refill cycle was confirmed by measuring the application cycle of the drive waveform and the discharge speed. As the refill cycle, 10 KHz or more could be secured, and no significant refill deterioration was observed.

  Liquid chamber for anisotropic etching ink.

  The ink common liquid chamber is formed from the back surface by anisotropic etching using an alkaline aqueous solution until the pressure generation chamber is formed by anisotropic etching until the pressure generation chamber is formed. As the alkaline aqueous solution, a KOH aqueous solution having a concentration of 20% by weight was used, and the treatment was performed at 80 ° C. After that, using an ICP-RIE apparatus, etching was performed in a direction perpendicular to the pressure generation chamber using a gas containing SF6 as a main component to form a communication port. Accordingly, since the size of the throttle between the ink common liquid chamber and the pressure generation chamber and the communication port and the pressure generation chamber are communicated with each other, the etching can be controlled independently, so that more precise processing is possible.

  Subsequent vibration plate formation, piezoelectric element formation, nozzle plate bonding, ink supply member and flexible cable were joined in the same manner as in Example 1 to complete the ink jet head.

  As a result of the same evaluation as in Example 1, stable droplet flight of about 9 m / s and about 8 pl was confirmed from the head. Further, by ensuring the rigidity of the partition walls, no significant crosstalk was observed in the adjacent heads. Furthermore, the refill cycle was confirmed by measuring the application cycle of the drive waveform and the discharge speed. As the refill cycle, 10 KHz or more could be secured, and no significant refill deterioration was observed.

  By having a shape that narrows in the vertical direction from the diaphragm toward the nozzle as in this embodiment, the width of the pressure generating chamber is relatively enlarged, so that the amount of displacement can be prevented from being reduced, and crosstalk through the partition wall can be prevented. It was confirmed that prevention and deterioration of refilling were less likely to occur.

Sectional drawing of the nozzle row direction which shows a part of inkjet head concerning embodiment of this invention 1 is a longitudinal sectional view of a pressure generating chamber showing a part of an ink jet head according to an embodiment of the present invention. Schematic diagram showing bulkhead compliance Schematic diagram showing the progress of anisotropic wet etching of silicon Schematic diagram showing dry etching pattern The schematic diagram which shows the internal structure in embodiment of this invention Process sectional drawing which shows the manufacturing process of the inkjet head concerning embodiment of this invention Sectional view of the same process according to the embodiment of the present invention Conceptual diagram explaining diaphragm compliance Schematic diagram showing the taper structure in the conventional example Schematic diagram showing the taper structure in another conventional example Sectional drawing of the inkjet head in an example of this invention implementation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diaphragm 2 Pressure generating chamber 3 Communication port 4 Nozzle plate 5 Bulkhead 6 Lower electrode 7 Drive element 8 Upper electrode 9 Nozzle 10 Ink common liquid chamber 11 Restriction 12 Wet etching opening 13 Taper 14 Substrate having a communication port 15 First Diaphragm 16 Second diaphragm having dent 17 Diaphragm dent

Claims (19)

  It is composed of a drive element that expands and contracts by an applied signal, a diaphragm that forms part of each pressure generating chamber, a partition that separates the pressure generating chamber and each pressure generating chamber, an ink supply path, an ink supply liquid chamber, and a nozzle, In the inkjet head that ejects ink droplets from the nozzles by displacing the diaphragm by deformation of the driving element and increasing ink pressure in the pressure generating chamber corresponding to the driving element, the diaphragm is the main surface of the diaphragm An inkjet head comprising a plurality of different materials in the in-plane direction and a method for manufacturing the same.   2. An ink jet head comprising the diaphragm according to claim 1 formed of a part of single crystal silicon and a metal oxide, and a method for manufacturing the ink jet head.   2. The ink jet head according to claim 1, wherein the diaphragm according to claim 1 uses a portion of single crystal Si doped with at least one of B, Au, Pt, C, and Ti, and a metal oxide. The diaphragm according to any one of claims 1 to 3, wherein the (100) plane of single crystal Si is
An ink jet head formed by using the ink jet head and a method for manufacturing the ink jet head. 5. The inkjet head according to claim 1, wherein the metal oxide material formed together with the single crystal Si is formed of at least one of SiO _x , ZrSiO _x , and ZrO _x. And its manufacturing method.   6. The ink jet head according to claim 1, wherein the pressure chamber has a tapered shape so as to become narrower in the vertical direction from the diaphragm toward the nozzle.   7. The ink jet head according to claim 1, wherein the minimum width of the partition wall located between adjacent pressure generating chambers is 20 [mu] m or less. In the manufacturing method of the ink-jet head according to any one of claims 1 to 7,
1) A step of doping ions into single crystal Si.
2) A step of etching the doping layer into a plurality of lines intersecting the <110> and <011> orientations of single crystal Si.
3) A step of etching Si located under the doping layer using an alkaline aqueous solution.
4) A step of etching from the surface opposite to the doping layer to form an ink communication port and a common liquid chamber.
5) A step of forming a SiO _x layer by thermal oxidation treatment.
6) A step of forming a metal oxide film from the doping layer side.
A method for manufacturing an inkjet head, comprising:   9. An ink jet head and a method for manufacturing the same, wherein in the step of etching the doping layer according to claim 8 in a line shape, the line width of the etching is 4 [mu] m or less.   9. The method of manufacturing an ink-jet head according to claim 8, wherein the alkaline aqueous solution for etching Si under the doping layer is either KOH or EDP.   9. The method of manufacturing an ink-jet head according to claim 8, wherein the method of forming the ink communication port and the common liquid chamber from the opposite side to the doping layer is anisotropic dry etching. .   9. The method of manufacturing an ink jet head according to claim 8, wherein the method of forming the ink communication port from the side opposite to the doping layer is anisotropic dry etching, and the method of forming the common liquid chamber uses an alkaline aqueous solution. A method of manufacturing an ink-jet head, characterized by anisotropic etching.   9. The method of manufacturing an ink-jet head according to claim 8, wherein the metal oxide film is formed from the doping layer side by using at least one of LPCVD and PECVD.   9. The method of manufacturing an ink-jet head according to claim 8, wherein a flattening process is performed after film formation from the doping layer side.   The method of manufacturing an ink jet head, wherein the planarization treatment according to claim 14 is an etch back method.   16. An ink jet head according to claim 1, wherein a nozzle for ejecting ink is separately formed and pasted so as to communicate with a communication port communicating with the pressure chamber. .   17. The ink jet head according to claim 1, wherein the vibration plate drive element is formed of a thin film having a thickness of 10 [mu] m or less.   18. The ink jet head according to claim 17, wherein the vibration plate drive element is formed of a piezoelectric thin film having a film thickness of 10 [mu] m or less. The inkjet head according to any one of claims 1 to 18, comprising a plurality of drive elements, a diaphragm, a pressure generating chamber, and a nozzle, and means for supplying an electric signal for expanding and contracting each drive element. Recording device.

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