JP2008000982A - Liquid droplet delivering head, liquid droplet delivering apparatus, method for manufacturing liquid droplet delivering head and method for manufacturing liquid droplet delivering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet delivering head or the like equipped with an electrostatic actuator which is excellent in liquid droplet delivering performance and stability by highly precisely controlling a vibrational diaphragm thickness. <P>SOLUTION: The liquid droplet delivering head is equipped with at least nozzle holes 11, pressure chambers 31, a liquid feeding part 22, the vibrational diaphragms 36 formed at part of wall surfaces of the pressure chambers 31, discrete electrodes 41, and an electrode taking-out part 46b. The liquid droplet delivering head is formed by laminating a plurality of substrates. An SOI substrate 3 as one of a plurality of the substrates is composed of an SOI base material with an SiO<SB>2</SB>layer 37 interposed between a first silicon layer 36a and a second silicon layer 36b. At least a recessed part 31a of the pressure chamber 31 having a bottom face constituted of the SiO<SB>2</SB>layer 37, is formed at the first silicon layer 36a side of the SOI base material. A part corresponding to the bottom face of the recessed part 31a of the pressure chamber 31 of the second silicon layer 36b is made the vibrational diaphragm 36. An SiO<SB>2</SB>insulating film 38 opposed to the discrete electrode 41 is prepared at a surface of the vibrational diaphragm 36. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge head, a droplet discharge device, a method for manufacturing a droplet discharge head, and a method for manufacturing a droplet discharge device.

  In recent electrostatic drive type inkjet printers, the number of nozzles and the number of rows of inkjet heads are increasing for high-speed printing and multicolor printing of high-resolution images. The number of chambers (discharge chambers) is increasing, and the length of nozzle rows is increasing. In manufacturing such an ink jet head, a silicon substrate is bonded to an electrode substrate in which individual electrodes are patterned on a glass substrate in advance, and then the silicon substrate is thinned, and then pressure is applied to the silicon substrate. There is a method of forming each part of an ink flow path such as a chamber or a reservoir.

  In such a manufacturing method, when forming a diaphragm located below the pressure chamber, for example, a boron-doped layer is formed at a predetermined depth of the silicon substrate, the silicon substrate is etched with an aqueous potassium hydroxide solution, and boron-doped Etching was stopped by the layer to obtain a predetermined diaphragm thickness (see, for example, Patent Document 1).

  Further, for example, a film to be a vibration plate is formed as a polycrystalline silicon thin film or a single crystal silicon thin film by an ECR sputtering method, a thermal CVD method, and a laser annealing method, and the vibration plate is formed by such a thin film (for example, patents) Reference 2).

JP-A-9-234873 (page 4, FIG. 5) JP 2004-195904 (pages 7-8, FIG. 4)

  In the technique according to Patent Document 1, it is important to control the boron doped layer to a predetermined depth in order to control the thickness. However, due to variations in the diffusion process, the boron doped layer depth varies between substrates or within the substrate. As a result, there is a problem that the thickness accuracy of the diaphragm is lowered at the end of etching.

  In the technique according to Patent Document 2, since a film to be a diaphragm is obtained by film formation, the crystal density is coarser than bulk silicon and the mechanical strength is relatively low, so that the durability drive characteristics of the diaphragm are low. was there.

The present invention has been made to solve the above-described problems, and when forming a diaphragm or a pressure chamber on a silicon substrate, the SiO ₂ layer located inside the silicon substrate is used as an etching stop layer. , Droplet Discharge Head, Droplet Discharge Device, Droplet Discharge Head Manufacturing Method, and Droplet Discharge Device Manufacturing Method Having an Actuator Excellent in Ink Discharge Performance and Stability by Highly Controlling the Diaphragm Thickness Is intended to provide.

A droplet discharge head according to the present invention includes a nozzle hole that discharges a droplet, a pressure chamber that communicates with the nozzle hole and forms a part of a liquid channel, and a liquid supply unit that supplies liquid to the pressure chamber And at least a diaphragm formed on a part of the wall surface of the pressure chamber, an individual electrode disposed opposite to the diaphragm, and an electrode extraction portion of the individual electrode, and a plurality of substrates are laminated. The SOI substrate, which is one of the plurality of substrates, is a droplet discharge head, and is composed of an SOI base material in which an SiO ₂ layer is interposed between a first silicon layer and a second silicon layer. At least a concave portion of the pressure chamber whose bottom surface is constituted by the SiO ₂ layer is provided on the first silicon layer side of the material, and a portion corresponding to the concave bottom surface of the pressure chamber of the second silicon layer is a diaphragm and it is, the surface on which the SiO ₂ layer of the diaphragm is positioned on the opposite side The individual electrodes facing the SiO ₂ insulating film is one that is configured provided.
Accordingly, it is possible to provide a droplet discharge head including an electrostatic actuator having a highly accurate diaphragm thickness, improved droplet discharge performance, and excellent stability.

A droplet discharge head according to the present invention includes an electrode substrate having individual electrodes, a pressure chamber that forms part of a liquid flow path, and a vibration that is formed on a part of the wall surface of the pressure chamber and is disposed to face the individual electrode. An SOI substrate (cavity substrate) having a plate, a reservoir substrate having a liquid supply part for supplying a liquid to the pressure chamber, and a nozzle substrate having a nozzle hole communicating with the pressure chamber and discharging droplets It is configured by stacking.
As a result, a droplet discharge head having a four-layer structure with improved droplet discharge performance and excellent stability can be provided.

The droplet discharge head according to the present invention is provided with a common electrode extending from the first silicon layer through the SiO ₂ layer to the second silicon layer.
Thereby, even though the SiO ₂ layer is provided between the first silicon layer and the second silicon layer, the common electrode penetrates the SiO ₂ layer and comes into contact with the second silicon layer. One substrate can maintain the electrode function.

A droplet discharge apparatus according to the present invention includes the above-described droplet discharge head.
As a result, it is possible to provide a droplet discharge device including a droplet discharge head with improved ink discharge performance and excellent stability.

A method for manufacturing a droplet discharge head according to the present invention includes a nozzle hole for discharging a droplet, a pressure chamber that communicates with the nozzle hole and forms a part of a liquid flow path, and supplies a liquid to the pressure chamber. A droplet discharge head comprising at least a liquid supply unit, a diaphragm formed on a part of a wall surface of the pressure chamber, an individual electrode disposed to face the diaphragm, and an electrode extraction unit of the individual electrode A method of manufacturing, comprising filling an SiO ₂ layer between silicon substrates to form an SOI substrate having a first silicon layer and a second silicon layer on both sides of the SiO ₂ layer; A step of providing a SiO ₂ insulating film on the surface of the second silicon layer of the SOI substrate opposite to the surface on which the SiO ₂ layer is located, etching the first silicon layer and stopping the etching by the SiO ₂ layer; It forms a recess serving as the pressure chamber of the bottom and the SiO ₂ layer Te And manufacturing a droplet discharge head by forming an SOI substrate from the silicon base material through at least the above-described process. It is.
Thus, since the SiO ₂ layer filled in the SOI substrate is used as an etching stop layer when forming the diaphragm, the rate selectivity can be extremely increased, and the diaphragm thickness can be easily controlled with high accuracy. It becomes possible to do. Further, since the SiO ₂ layer of the SOI base material is used for the actuator electrical insulating film, the process can be simplified. Thus, a droplet discharge head with improved droplet discharge performance and excellent stability can be provided.

Further, in the method for manufacturing a droplet discharge head according to the present invention, the step of forming the SOI substrate includes implanting oxygen ions into the silicon substrate by an oxygen ion beam, annealing the silicon substrate, This is performed by a step of forming the SiO ₂ layer between silicon substrates.
Since the thickness of the diaphragm is controlled by using the SiO ₂ layer filled between the first and second silicon layers as an etching stop layer, the rate selection ratio can be extremely increased, and high-precision diaphragm thickness control is easy. To be able to do

Also, the method for manufacturing a droplet discharge head according to the present invention includes dry etching on the silicon substrate after the step of etching the first silicon layer and forming a diaphragm on the bottom surface of the concave portion serving as the pressure chamber. And forming an opening extending from the first silicon layer through the SiO ₂ layer to the second silicon layer, and attaching a common electrode to the opening.
In this way, the common electrode is embedded to the position where it passes through the intermediate SiO ₂ layer and directly contacts the second silicon layer, and the electrode function of the silicon substrate is maintained.

In the method of manufacturing a droplet discharge head according to the present invention, the opening for attaching the common electrode is penetrated to the surface of the second silicon layer or a position deeper than the surface.
In this way, the common electrode is buried through the intermediate SiO ₂ layer to a position in direct contact with the second silicon layer, that is, to the surface of the second silicon layer or deeper than that. The electrode function of the substrate is reliably maintained.

The method for manufacturing a droplet discharge device according to the present invention is a method for manufacturing a droplet discharge device using any of the above-described methods for manufacturing a droplet discharge head.
As a result, it is possible to provide a droplet discharge device including a droplet discharge head with improved droplet discharge performance and excellent stability.

Embodiment 1 FIG.
Hereinafter, embodiments of a droplet discharge head manufactured by the manufacturing method of the present invention will be described with reference to the drawings. Here, as an example of a droplet discharge head, a face discharge type electrostatic drive type inkjet head will be described with reference to FIGS. The present invention is not limited to the structure and shape shown in the following drawings, and can be similarly applied to an edge discharge type droplet discharge head.

  FIG. 1 is an exploded perspective view showing a schematic configuration of an inkjet head according to Embodiment 1 of the present invention, including a part of an FPC (Flexible Printed Circuit) for supplying an input signal. FIG. 2 is a cross-sectional view showing a schematic configuration of the right half of the assembled ink jet head of FIG. 1 and 2 schematically show a lead portion for supplying an input signal to the driver IC. Moreover, in FIG. 1 and FIG. 2, the state normally used is shown upside down.

An inkjet head (an example of a droplet discharge head) 10 according to Embodiment 1 shown in FIGS. 1 and 2 is a nozzle substrate, a cavity substrate, and an electrode substrate as in a conventional general electrostatic drive type inkjet head. This is not a three-layer structure in which the three substrates are bonded together, but a four-layer structure in which the four substrates of the nozzle substrate 1, the reservoir substrate 2, the cavity substrate 3, and the electrode substrate 4 are bonded together. The nozzle substrate 1 is bonded to one surface of the reservoir substrate 2, and the cavity substrate 3 is bonded to the other surface of the reservoir substrate 2. An electrode substrate 4 is bonded to the surface of the cavity substrate 3 opposite to the surface to which the reservoir substrate 2 is bonded. That is, in FIG. 1 and FIG. 2, the electrode substrate 4, the cavity substrate 3, the reservoir substrate 2, and the nozzle substrate 1 are joined in this order from the bottom. The method for manufacturing the cavity substrate 3 will be described in detail later. Actually, the cavity substrate 3 is made of a silicon base material bonded to the electrode substrate 4. In the following description, for the sake of convenience of explanation, the upper surface of each substrate in the drawing is referred to as “upper surface or front surface”, and the lower surface in the drawing is referred to as “lower surface or back surface”.
In addition, the inkjet head 10 is provided with a driver IC 5 that supplies a drive signal to an individual electrode 41 described later.

  First, the nozzle substrate 1 is made of a silicon single crystal substrate having a thickness of about 50 μm, for example. The nozzle substrate 1 is provided with two rows of nozzle holes 11 at a predetermined pitch. Each nozzle hole 11 includes an injection port portion 11a having a small hole perpendicular to and coaxially with the substrate surface and an introduction port portion 11b having a diameter larger than that of the injection port portion 11a. Further, the end portions on both sides of the nozzle substrate 1 are notched in a U shape like the reservoir substrate 2 and the cavity substrate 3, and this notch portion 7a is for FPC connection for connecting the FPC 6. An opening 7 is formed.

  Next, the reservoir substrate 2 is made of, for example, a silicon single crystal substrate having a thickness of about 180 μm. The reservoir substrate 2 is provided with a nozzle communication hole 21 having a slightly larger diameter (a diameter equal to or larger than the diameter of the introduction port portion 11 b) that penetrates the reservoir substrate 2 and communicates with each nozzle hole 11. A recess 23 serving as a common reservoir (common ink chamber) 22, a supply port 24 that communicates the reservoir 22 with each pressure chamber 31 of the cavity substrate 3, and a central portion for mounting the driver IC 5. A rectangular opening 8a is provided as an IC mounting opening 8.

An ink supply hole 26 for supplying ink from an ink cartridge (not shown) through the electrode substrate 4 and the cavity substrate 3 is provided at the bottom of the recess 23 serving as each reservoir 22. Further, at both ends of the reservoir substrate 2, as described above, the U-shaped cutout portions 7 b serving as the FPC connection openings 7 are provided.
In addition, in order to prevent an increase in flow resistance in the pressure chamber 31 due to the thinning of the cavity substrate 3, a supply channel having a narrow groove shape communicating with the pressure chamber 31 and the nozzle communication hole 21 is provided on the lower surface of the reservoir substrate 2. 28 (see FIG. 2) is provided.

  Since the nozzle communication hole 21 penetrating the reservoir substrate 2 is provided coaxially with the nozzle hole 11 of the nozzle substrate 1, it is possible to obtain straightness of ink droplet ejection, and thus the ejection characteristics are remarkably improved. Become. In particular, since minute ink droplets can be landed as intended, gradation changes can be faithfully reproduced without causing color misregistration and the like, and a clearer and higher quality image can be realized.

Next, the cavity substrate (SOI substrate) 3 is manufactured using an SOI (Silicon On Insulator) base material having an electrode function of, for example, a thickness of about 30 μm. The SOI substrate which was composed by interposing the SiO ₂ layer 37 on the silicon substrate 300, SiO ₂ layer 37 functions as an etching stop layer when forming the diaphragm (described later) in the silicon substrate. A first silicon layer 36a is formed on one side (upper surface side) via the SiO ₂ layer 37 of the SOI base material, and a _second silicon layer 36b is formed on the other side (lower surface side). . The first silicon layer 36 a is provided with a recess 31 a serving as a pressure chamber (discharge chamber) 31 communicating with the nozzle communication hole 21 and the supply path 28. The diaphragm 36 is constituted by the second silicon layer 36 b on the bottom wall of the recess 31 a serving as the pressure chamber 31 via the SiO ₂ layer 37.

An SiO ₂ insulating film 38 is formed on the lower surface of the diaphragm 36 of the SOI base material, and this insulating film 38 prevents dielectric breakdown and short circuit when the inkjet head 10 is driven. A TEOS film 35 serving as an etching mask is formed on the upper surface of the first silicon layer 36a of the SOI base material.
The cavity substrate 3 thus configured is provided with an ink supply hole 33 communicating with the reservoir 22 of the reservoir substrate 2, and at both ends, a U-shape that serves as the FPC connection opening 7 as described above. The notch 7c is provided. A pair of common electrodes 39 are embedded and attached to both sides of the notch portion 7c so as to penetrate the first silicon layer 36a and the SiO ₂ layer 37 from the TEOS film 35 to reach the surface of the second silicon layer 36b. It has been. The pair of common electrodes 39 may be embedded to a position deeper than the SiO ₂ layer position, that is, to the second silicon layer 36b. Since the SiO ₂ layer 37 is provided between the first silicon layer 36a and the second silicon layer 36b having the electrode function, the common electrode 39 penetrates through the SiO ₂ layer 37 and the second silicon layer 36b. This is because it is necessary to embed up to a position in contact with the silicon layer 36b.

  A COM wiring 62 of the FPC 6 is connected to the common electrode 39 using a conductive adhesive or the like. In addition, a rectangular opening 8 b serving as an IC mounting opening 8 for mounting the driver IC 5 is provided at the center of the cavity substrate 3. The IC mounting opening 8 communicates with a gap (interelectrode gap or gap) 42 formed between the diaphragm 36 and the individual electrode 41 via a sealing hole 46a of the electrode extraction portion 46b. Yes.

  Next, the electrode substrate 4 is made of, for example, a glass substrate having a thickness of about 1 mm. Among them, it is suitable to use a borosilicate heat-resistant hard glass having a thermal expansion coefficient close to that of the silicon base material of the cavity substrate 3. This is because when the electrode substrate 4 and the silicon base material are anodically bonded, the thermal expansion coefficients of the two substrates are close to each other, so that the stress generated between the electrode substrate 4 and the silicon base material can be reduced. This is because the electrode substrate 4 and the silicon base material can be firmly bonded without causing the above problems.

The electrode substrate 4 is provided with two rows of recesses (gap stepped portions) 42a in parallel at positions facing the diaphragms 36 of the cavity substrate 3 respectively. A groove 43 communicating with each recess 42 a is provided in the center of the electrode substrate 4 between the two rows of recesses 42 a. Each recess 42a and the central groove 43 are formed to a depth of about 0.3 μm by etching. In general, individual electrodes 41 made of ITO (Indium Tin Oxide) are formed on the bottom surface of each recess 42a by sputtering, for example, with a thickness of 0.1 μm. Therefore, the gap 42 formed between the diaphragm 36 and the individual electrode 41 is determined by the depth of the recess 42 a and the thickness of the SiO ₂ insulating film 38 that covers the individual electrode 41 and the diaphragm 36. The gap 42 greatly affects the ejection characteristics of the inkjet head. In the case of the first embodiment, the gap 42 is 0.2 μm. The sealing hole 46a of the gap 42 is sealed with a sealing material 46 made of an epoxy adhesive or the like. Thereby, moisture, dust, etc. can be prevented from entering the gap 42, and the reliability of the inkjet head 10 can be maintained.

  Further, a lead portion 44 for connection to the driver IC 5 and the FPC 6 is also formed in the central groove portion 43 by an ITO pattern. The lead part 44 is composed of a plurality of leads (wirings). In the first embodiment, the lead portion 44 refers to a plurality of leads connected to one driver IC 5. The lead part 44 is an FPC mounting part 44a connected to the IC input wiring 61 of the FPC 6 at the end of the electrode substrate 4, and the IC input mounting part 44b connected to the input terminal of the driver IC 5 at two locations. 44c and an IC input signal wiring 44d wired under the driver IC 5. The output terminal of the driver IC 5 is connected to the individual electrode 41 in each column.

Thus, since the wiring of the lead part 44 is formed in a state sandwiched between the electrode substrate 4 and the driver IC 5, it is possible to perform wiring compactly without increasing the area of the inkjet head 10 (large in the lateral direction). .
Further, since the lead portion 44 is made of ITO like the individual electrode 41, it can be formed simultaneously with the individual electrode 41, and the manufacturing process can be simplified.
The material of the individual electrode 41 and the lead part 44 is not limited to ITO, but metal such as gold or copper may be used. However, since ITO is transparent, it is easy to check whether or not it has been discharged. For this reason, ITO is generally used.
In addition, ink supply holes 45 connected to an ink cartridge (not shown) are provided on both sides of the electrode substrate 4 as described above.

  Here, the operation of the inkjet head 10 configured as described above will be described. One end of the FPC 6 is connected to a control unit (not shown) of the inkjet head 10, the COM wiring 62 at the other end is connected to the common electrode 39 of the cavity substrate 3, and the IC input wiring 61 is an electrode The driver IC 5 mounted on the electrode substrate 4 is connected via the lead portion 44 of the substrate 4. Accordingly, when a drive signal (pulse voltage) is supplied from the control unit (not shown) of the inkjet head 10 to the driver IC 5, the pulse voltage is applied from the driver IC 5 to the individual electrode 41, and the individual electrode 41 is charged positively. On the other hand, the corresponding diaphragm 36 is negatively charged. At this time, since an electrostatic force (Coulomb force) is generated between the individual electrode 41 and the diaphragm 36, the diaphragm 36 is attracted toward the individual electrode 41 by the electrostatic force and bent. As a result, the volume of the pressure chamber 31 increases. Next, when the pulse voltage is turned off, the electrostatic force disappears, and the vibration plate 36 returns to its original state due to its elastic force. At this time, the volume of the pressure chamber 31 is rapidly reduced. Part of the ink in the chamber 31 passes through the nozzle communication hole 21 and is ejected from the nozzle hole 11 as ink droplets. Then, the pulse voltage is applied again, and the vibration plate 36 bends toward the individual electrode 41, whereby ink is supplied from the reservoir 22 through the supply port 24 into the pressure chamber 31.

  As described above, according to the ink jet head 10 according to the first embodiment, the nozzle substrate 1, the reservoir substrate 2, the cavity substrate 3, and the electrode substrate 4 are combined to form a four-layer structure so that a plurality of drivers are provided inside. An IC 5 can be mounted, and a high-performance inkjet head that is small and has multiple nozzles can be configured.

  Next, a method for manufacturing the inkjet head 10 will be described with reference to FIGS. 3 to 7, the inkjet head 10 shown in FIG. 1 is bilaterally symmetric, and therefore, for the sake of convenience, the right half of the cross section is shown. In practice, the left portion is also formed at the same time. Further, the thickness of the substrate and the etching depth shown below are merely examples, and the present invention is not limited to this.

(A) First, as shown in FIG. 3A, for example, a single crystal (110) silicon substrate 300 having a thickness of about 220 μm and subjected to surface processing and removal processing (pretreatment) of the surface damaged layer is prepared. To do.

(B) Next, as shown in FIG. 3B, oxygen ions are implanted into the silicon substrate 300 by an oxygen ion beam. Oxygen ions are implanted under conditions of a substrate temperature of 400 ° C., an acceleration energy of 180 keV, and an oxygen dose of 4 × 10 ¹⁷ cm ⁻² .

(C) Next, the silicon substrate 300 is annealed at a high temperature as shown in FIG. The high temperature annealing is performed at a temperature of 1350 ° C. (1300 ° C. or higher) for 4 hours. As a result, the SiO ₂ layer 37 is formed inside the silicon substrate 300. The upper part of the SiO ₂ layer 37 becomes the first silicon layer 36a, and the lower part becomes the second silicon layer 36b which is thinner than this. Thus, an SOI (Silicon On Insulator) base material is formed.

(D) Next, as shown in FIG. 3 (d), the surface (lower surface) of the second silicon layer 36b of the silicon substrate 300 is thickened by, for example, plasma CVD (Chemical Vapor Deposition) using TEOS as a raw material. An insulating film (SiO ₂ insulating film) 38 made of an oxide film of 0.1 μm is formed. The insulating film 38 is formed, for example, at a temperature of 360 ° C., a high frequency output of 250 W, a pressure of 66.7 Pa (0.5 Torr), a gas flow rate of TEOS flow rate of 100 cm 3 / min (100 sccm), and an oxygen flow rate of 1000 cm 3 / min (1000 sccm). Perform under conditions.

(E) Next, as shown in FIG. 4 (e), the silicon substrate 300 is preliminarily formed on the glass substrate via the SiO ₂ insulating film 38 on the individual electrodes 41, the recesses 42 a, lead portions (not shown), The anodic bonding is carried out on the electrode substrate 4 produced by facing the individual electrodes 41. In anodic bonding, the silicon substrate 300 and the electrode substrate 4 are heated to 360 ° C., and then a negative electrode is connected to the electrode substrate 4 and a positive electrode is connected to the silicon substrate 300, and a voltage of 800V is applied to perform anodic bonding. Further, the ink supply hole 45 is formed in the electrode substrate 4 by cutting using a drill or the like, for example.

(F) Next, the surface of the anodic bonded silicon substrate 300 is ground by, for example, a back grinder or a polisher, and further, for example, the surface is etched by 10 to 20 μm with a hydrofluoric acid aqueous solution to remove the work-affected layer. As shown in FIG. 4F, the thickness is reduced until the thickness reaches, for example, 30 μm.

(G) Next, as shown in FIG. 4G, a TEOS film 35 serving as an etching mask is formed on the surface of the thinned silicon substrate 300 to a thickness of about 0.8 μm by, for example, plasma CVD. To do.

(H) Next, a resist (not shown) is formed on the surface of the TEOS film 35, and the resist is patterned and etched by photolithography, whereby the pressure chamber 31 and the ink are formed as shown in FIG. An opening corresponding to the supply hole 33, the FPC connection opening (not shown), and the IC mounting opening 8 of the driver IC 5 is formed in the TEOS film 35.

(I) Next, by etching this anodic bonded substrate with an aqueous potassium hydroxide solution, a concave portion 31a to be a pressure chamber 31 is formed on the thinned silicon base material 300 as shown in FIG. Then, a portion 33 a to be the ink supply hole 33, a portion 8 a to be the IC mounting opening 8, and a portion 7 c to be the FPC connection opening 7 are formed.
At this time, the concave portion 31a serving as the pressure chamber 31, the portion 33a serving as the ink supply hole 33, the portion 8a serving as the IC mounting opening 8, and the portion 7c serving as the FPC connection opening 7 are disposed on the first silicon layer 36a. Although it is formed by etching, the etching stops when it reaches the surface of the SiO ₂ layer 37 that functions as an etching stop layer provided in the silicon substrate 300.
At this time, in the portion of the recess 31a that becomes the pressure chamber 31, the diaphragm 36 is formed in a state in which the second silicon layer 36b located on the lower surface of the SiO ₂ layer 37 maintains a constant diaphragm thickness with high accuracy.

In the above etching process, first, etching is performed using a potassium hydroxide aqueous solution having a concentration of 35 wt% until the remaining thickness of the first silicon layer 36 a becomes, for example, 5 μm, and then water having a concentration of 3 wt%. Etching is performed by switching to a potassium oxide aqueous solution. Thereby, the etching stop sufficiently works, so that the surface roughness of the SiO ₂ layer 37 located on the vibration plate 36 can be prevented, and the portion to be the vibration plate 36 can be formed with a high accuracy thickness. Etching stop is defined as a state in which bubbles generated from the etching surface are stopped, and in actual wet etching, it is determined that the etching is stopped when the generation of bubbles is stopped. Then, after etching, the resist is peeled off.

(J) Next, as shown in FIG. 6 (j), a silicon mask 302 is set on the silicon substrate 300 on which the recess 31a to be the pressure chamber 31 is formed, and RIE (Reactive Ion Etching) dry etching is performed. The IC mounting opening 8 (including the electrode extraction part 46b), the FPC connection opening (not shown), and the ink supply hole 33 are opened. The etching conditions are, for example, a high frequency output of 200 W, a chamber pressure of 39.9 Pa (0.3 Torr), a CF ₄ gas flow rate of 30 cm 3 / min (30 sccm), and an etching time of 60 minutes.

(K) Next, as shown in FIG. 6 (k), a silicon mask 303 different from the silicon mask 302 is set on the silicon substrate 300, and the common electrode 39 is embedded by RIE dry etching. The opening 39a is formed from the TEOS film 35 to the position where it penetrates the first silicon layer 36a and the SiO ₂ layer 37 and contacts the second silicon layer 36b. The opening 39a may be formed to a position below the surface of the second silicon layer 36b (a position deeper than the intermediate SiO ₂ layer 37). For example, the etching depth is set to about 35 μm.

(L) Next, as shown in FIG. 6 (l), using the silicon mask 303, for example, Pt is sputtered into the opening 39a opened as described above, and the common electrode 39 is embedded.

(M) Next, as shown in FIG. 6 (m), the sealing hole 46 a of the gap 42 located in the electrode extraction portion 46 b is sealed with a sealing material 46.
As described above, the cavity substrate 3 can be manufactured in a state in which the silicon substrate 300 is bonded to the electrode substrate 4 on which the individual electrodes 41 are patterned.

(N) After that, as shown in FIG. 7 (n), the reservoir substrate 2 on which the nozzle communication hole 21, the reservoir 22, and the supply port 24 are formed in advance is formed on the cavity substrate 3 manufactured as described above. Adhere to the adhesive. At this time, the reservoir substrate 2 and the cavity substrate 3 are bonded via the TEOS film 35.

(O) Next, as shown in FIG. 7 (o), the driver IC 5 is set on the groove 43 of the electrode substrate 4 from the IC mounting opening 8 of the cavity substrate 3, and the individual electrodes 41 and lead portions ( Connected to the FPC (not shown) IC input wiring to the end of the lead portion (FPC mounting portion), the FPC COM wiring to the common electrode 38, and conductive adhesive Use to connect.

(P) Finally, as shown in FIG. 7 (p), the nozzle substrate 1 in which the nozzle holes 11 are formed in advance is bonded onto the reservoir substrate 2 with an adhesive. And if it isolate | separates into each head by dicing, the inkjet head 10 shown in FIG. 2 will be produced.

As described above, according to the ink jet head according to the first embodiment, since the internal SiO ₂ layer 37 is used as an etching stop layer when the diaphragm 36 is formed, the rate selectivity can be extremely increased. High-precision diaphragm thickness control can be easily performed. Further, since the SiO ₂ layer 37 of the SOI base material is used for the electrical insulating film of the actuator, the process can be simplified. Thus, it is possible to provide an electrostatic drive type ink jet head excellent in ink discharge performance and stability.

Although the ink jet head as an example of the liquid droplet ejection head has been described in the first embodiment, the liquid droplet ejection head is not limited to the ink jet head, and the color of the liquid crystal display can be changed by variously changing the liquid droplets. The present invention can also be applied to the manufacture of filters, the formation of light emitting portions of organic EL display devices, the discharge of biological liquids, and the like.
In the first embodiment, an ink jet head having a four-layer structure has been described. However, the present invention is not limited to the first embodiment, and various modifications can be made within the scope of the idea of the present invention. For example, the present invention can be applied to a conventional general three-layer ink jet head.

Embodiment 2. FIG.
FIG. 8 is a perspective view of an ink jet printer (an example of a droplet discharge device) according to Embodiment 2 of the present invention. An ink jet printer 500 as shown in FIG. 8 can be obtained using the ink jet head obtained in the first embodiment.
According to the second embodiment, it is possible to provide a highly reliable ink jet printer provided with an ink jet head having a pressure chamber that has stable and high electrical insulation and excellent airtightness.

1 is an exploded perspective view showing a schematic configuration of an inkjet head according to Embodiment 1 of the present invention. Sectional drawing which shows schematic structure of the right half which assembled the inkjet head of FIG. Sectional drawing of the manufacturing process of the inkjet head of this invention. Sectional drawing of the manufacturing process following FIG. Sectional drawing of the manufacturing process following FIG. Sectional drawing of the manufacturing process following FIG. Sectional drawing of the manufacturing process following FIG. 1 is a perspective view showing an ink jet printer according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle substrate, 2 Reservoir substrate, 3 Cavity substrate (SOI substrate), 4 Electrode substrate, 5 Driver IC, 8 IC mounting opening, 10 Inkjet head, 11 Nozzle hole, 22 Reservoir, 26 Ink supply hole, 31 Pressure chamber , 31a Pressure chamber, 33 ink supply hole, 35 TEOS film, 36 diaphragm, 36a first silicon layer, 36b second silicon layer, 37 SiO ₂ layer, 38 SiO ₂ insulating film, 39 common electrode, 39a Opening for embedding the common electrode, 41 Individual electrode, 42 Gap, 42a Recess (gap step), 43 Groove, 44 Lead, 45 Ink supply hole, 46 Sealing material, 46a Sealing hole, 46b Electrode extraction unit, 300 Silicon substrate, 302, 303 Silicon mask, 500 Inkjet printer.

Claims (9)

A nozzle hole for discharging droplets, a pressure chamber that communicates with the nozzle hole and forms part of the liquid flow path, a liquid supply unit that supplies liquid to the pressure chamber, and a part of the wall surface of the pressure chamber A droplet discharge head comprising at least a diaphragm formed on the substrate, an individual electrode disposed opposite to the diaphragm, and an electrode extraction portion of the individual electrode, wherein a plurality of substrates are laminated,
The SOI substrate, which is one of the plurality of substrates, comprises an SOI base material in which a SiO ₂ layer is interposed between a first silicon layer and a second silicon layer, and the first silicon layer of the SOI base material At least a concave portion of the pressure chamber whose bottom surface is constituted by the SiO ₂ layer is provided, and a portion corresponding to the concave bottom surface of the pressure chamber of the second silicon layer is a diaphragm, A droplet discharge head comprising a SiO ₂ insulating film facing the individual electrode on a surface opposite to a surface on which the SiO ₂ layer is located.   The droplet discharge head includes an electrode substrate having individual electrodes, a pressure chamber that forms part of a liquid flow path, and a diaphragm that is formed in a part of the wall surface of the pressure chamber and is disposed to face the individual electrodes. And an SOI substrate, a reservoir substrate having a liquid supply unit for supplying a liquid to the pressure chamber, and a nozzle substrate having nozzle holes that communicate with the pressure chamber and discharge droplets. The droplet discharge head according to claim 1. 3. The liquid droplet ejection head according to claim 1, further comprising a common electrode extending from the first silicon layer through the SiO ₂ layer to reach the second silicon layer.   A droplet discharge apparatus comprising the droplet discharge head according to claim 1. A nozzle hole for discharging droplets, a pressure chamber that communicates with the nozzle hole and forms part of the liquid flow path, a liquid supply unit that supplies liquid to the pressure chamber, and a part of the wall surface of the pressure chamber A manufacturing method of a liquid droplet ejection head comprising at least a diaphragm formed on the substrate, an individual electrode disposed opposite to the diaphragm, and an electrode extraction portion of the individual electrode,
Filling an SiO ₂ layer between silicon substrates to form an SOI substrate having a first silicon layer and a second silicon layer on both sides of the SiO ₂ layer;
Providing a SiO ₂ insulating film on the surface of the SOI substrate opposite to the surface on which the SiO ₂ layer of the second silicon layer is located;
Wherein the first silicon layer of the SOI substrate by etching the bottom surface by etching stop forming the recess to serve as the pressure chamber to the SiO ₂ layer by the SiO ₂ layer, the second located on the bottom surface of the recess And at least a step of using the silicon layer as a diaphragm,
A method for manufacturing a droplet discharge head, comprising manufacturing an droplet discharge head by forming an SOI substrate from the silicon base material through at least the above steps. The step of forming the SOI substrate includes the step of injecting oxygen ions into the silicon substrate by an oxygen ion beam, annealing the silicon substrate, and forming the SiO ₂ layer between the silicon substrates. 6. The method of manufacturing a droplet discharge head according to claim 5, wherein the method is performed. After the step of etching the first silicon layer and forming a diaphragm on the bottom surface of the recess that becomes the pressure chamber, the silicon substrate is dry-etched and penetrates the SiO ₂ layer from the first silicon layer. 7. The method of manufacturing a droplet discharge head according to claim 5, further comprising forming an opening reaching the second silicon layer and attaching a common electrode to the opening.   8. The method of manufacturing a droplet discharge head according to claim 7, wherein the opening for attaching the common electrode is penetrated to the surface of the second silicon layer or a position deeper than the surface. A method for manufacturing a droplet discharge device, wherein the droplet discharge device is manufactured using the method for manufacturing a droplet discharge head according to claim 5.

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