JP2007118393A - Liquid jet head manufacturing method and liquid jet device provided with liquid jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid jet head in which discharge characteristics are stabilized by preventing occurrence of projecting etching residues on an etching face of a vibrating plate manufactured by etching, and a liquid jet device provided with the liquid jet head. <P>SOLUTION: A pressure chamber of a flow passage forming substrate and the vibrating plate are formed by performing a first etching step, in which a high-concentration boron-doped layer is formed on one face of an Si substrate and etching is performed from the other face opposite to the one face to the halfway of the Si substrate with an etchant having a concentration adjusted to ≤30 wt.%, and then, a second etching step in which etching is performed from the part etched in the first etching step to a part reaching the high-concentration boron-doped layer with an etchant having a concentration lower than that of the etchant used in the first etching step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a liquid ejecting head capable of ejecting liquid as droplets from a nozzle opening, and a liquid ejecting apparatus including a liquid ejecting head obtained by the manufacturing method.

  The liquid ejecting apparatus includes a liquid ejecting head capable of ejecting liquid as droplets, and ejects various liquids from the liquid ejecting head. As a typical example of this liquid ejecting apparatus, for example, an ink jet recording apparatus that includes an ink jet recording head (hereinafter referred to as a recording head) and performs recording by ejecting liquid ink from the recording head as ink droplets. Hereinafter, an image recording apparatus such as a printer) may be used. In recent years, the present invention is applied not only to this image recording apparatus but also to various manufacturing apparatuses such as a display manufacturing apparatus.

  As a recording head mounted on a printer which is a kind of the liquid ejecting apparatus, a pressure chamber communicating with a nozzle opening, a common ink chamber for introducing a liquid to be supplied to the pressure chamber, and the common ink chamber and the pressure chamber are provided. An ink supply path that communicates and supplies the ink in the common ink chamber to the pressure chamber side, and operates the drive means to cause pressure fluctuation in the liquid in the pressure chamber, whereby the ink in the pressure chamber is ejected from the nozzle opening. Some are configured to be ejected as droplets. As this recording head, there are various drive systems. For example, a pressure generating element such as a piezoelectric vibrator or a heating element is provided, and an ink droplet is ejected by operating the pressure generating element, or a pressure generated by an electrostatic force generated between opposing electrodes. There is one configured to eject an ink droplet by elastically deforming an elastic surface (vibration plate) that partitions a chamber (for example, Patent Document 1).

  In a recording head that uses such electrostatic force as a driving means, the elastic deformation characteristics of the vibration plate greatly affect the ink droplet ejection characteristics. Therefore, if the thickness of the vibration plate formed by etching the Si substrate is uneven. There was a problem that the rigidity in the diaphragm was not constant and the discharge characteristics were not stable. Therefore, in order to reduce the surface roughness of the etched surface and improve the thickness accuracy of the diaphragm, the Si substrate on which the high concentration boron-doped layer is formed and the oxide film is patterned is highly concentrated with a 35 wt% potassium hydroxide aqueous solution. A recording head manufacturing method has been adopted in which etching is performed immediately before reaching the boron-doped layer, and then etching is continued with a 5 wt% potassium hydroxide aqueous solution to stop etching (for example, Patent Document 2).

Japanese Patent Laid-Open No. 06-071882 JP 2004-136694 A

  However, in the manufacturing methods of the above-mentioned documents, the number of recording heads with unstable ejection characteristics has been reduced, but it has not disappeared. Then, in pursuit of the cause of the unstable discharge characteristics, when the diaphragm in the flow path forming substrate is manufactured by etching, the protrusion generated on the etching surface located on the outer periphery of the Si substrate (Si wafer) as the base material. It was presumed to be caused by the residual etching. Therefore, when the ejection characteristics of the recording head provided with the vibration plate having no convex etching residue were inspected, it was found that the ejection characteristics were stable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid ejecting head in which ejection characteristics are stabilized by preventing occurrence of convex etching residue of a vibration plate produced by etching. A manufacturing method and a liquid ejecting apparatus including the liquid ejecting head are provided.

The method of manufacturing a liquid jet head according to the present invention has been proposed to achieve the above-described object, and includes a pressure chamber communicating with a nozzle opening for discharging droplets and a vibration partitioning at least one surface of the pressure chamber. A liquid jet head manufacturing method comprising: a flow path forming substrate having a plate; and a driving unit that changes the volume of the pressure chamber by deforming the vibration plate, wherein the flow path forming substrate is made of an Si substrate.
A high-concentration p-type impurity layer is formed on one surface of the Si substrate, and etching is performed with an etching solution whose concentration is adjusted to 30 wt% or less from the surface opposite to the surface to the middle of the Si substrate. And then etching is performed with an etchant having a lower concentration than the etchant used in the first etching step until the high-concentration p-type impurity layer is reached after the etching in the first etching step. The pressure chamber of the flow path forming substrate and the vibration plate are formed by performing the etching step 2.
Note that “30 wt% or less” does not include 0%.

  According to the above method, the high-concentration p-type impurity layer is formed on one surface of the Si substrate and the concentration is adjusted to 30 wt% or less from the surface opposite to the surface to the middle of the Si substrate. Etching is performed at a lower concentration than the etching solution used in the first etching process until the high-concentration p-type impurity layer is reached after the etching in the first etching process is performed after the first etching process is performed. Since the pressure chamber of the flow path forming substrate and the vibration plate are formed by performing the second etching step of etching with a liquid, the surface roughness of the bottom surface on the pressure chamber side made by etching of the vibration plate is formed. The degree can be reduced and the maximum height of the convex etching residue on the surface can be suppressed. Thereby, the thickness of the diaphragm can be made highly accurate, and the maximum height of the remaining convex etching of the diaphragm can be suppressed to an allowable range or less, so that the rigidity in the diaphragm can be made constant. it can. Accordingly, the elastic deformation of the diaphragm can be made uniform, and the ejection characteristics of the liquid ejecting head can be further stabilized.

  In the above method, the etching solution is preferably an aqueous potassium hydroxide solution.

  In each of the above methods, the concentration of the etching solution used in the second etching step is preferably 0.5 to 10 wt%.

  According to the above method, since the concentration of the etchant used in the second etching step is 0.5 to 10 wt%, the high concentration p-type impurity layer is exposed when the high concentration p-type impurity layer is exposed by etching. Thus, the etching rate can be drastically reduced and the etching can be surely stopped. Therefore, the diaphragm composed of the high concentration p-type impurity layer can be formed with higher accuracy.

  In each of the above methods, the high concentration p-type impurity layer is a high concentration boron doped layer.

  Further, the liquid ejecting apparatus of the invention divides a pressure chamber communicating with a nozzle opening for discharging droplets and at least one surface of the pressure chamber, and the liquid ejecting head manufacturing method according to any one of the above methods The liquid ejection head includes a flow path forming substrate having a vibration plate formed by etching the Si substrate, and a driving unit that changes the volume of the pressure chamber by deforming the vibration plate.

  According to the above configuration, the thickness of the diaphragm in the flow path forming substrate can be made highly accurate, and the maximum height of the remaining convex etching of the diaphragm can be suppressed to an allowable range or less. The rigidity in the plate can be made constant. Accordingly, the elastic deformation of the diaphragm can be made uniform, and the ejection characteristics of the liquid ejecting head can be further stabilized. As a result, in the liquid ejecting apparatus including the liquid ejecting head, the image quality of the recorded image can be stabilized.

  The said structure WHEREIN: The surface roughness (PV) of the surface by the side of the said pressure chamber of the said diaphragm is a rough surface below 0.2 micrometer, It is characterized by the above-mentioned.

  In each of the above-described configurations, the maximum height of the convex etching residue generated on the pressure chamber side surface of the diaphragm is 0.35 μm or less.

  According to the above-described configurations, thickness unevenness of the diaphragm is suppressed and thickness accuracy is increased, so that the rigidity in the diaphragm can be made constant. Accordingly, the elastic deformation of the diaphragm can be made uniform, and the ejection characteristics of the liquid ejecting head can be stabilized.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following description, an ink jet recording apparatus (ink jet printer: hereinafter referred to as a printer) will be described as an example of the liquid ejecting apparatus of the invention.

  FIG. 1 is a perspective view illustrating the basic configuration of the printer 1. As shown in FIG. 1, the printer 1 is provided with a recording head 2 that is a kind of liquid ejecting head, a carriage 4 to which an ink cartridge 3 is detachably attached, and a lower portion of the recording head 2. A platen 5, a carriage moving mechanism 7 for moving the recording head 2 (carriage 4) in the paper width direction of the recording paper 6 (a kind of discharge target), and a recording paper 6 in a paper feed direction that is a direction orthogonal to the head moving direction. And a paper feed mechanism 8 for conveying the paper. Here, the paper width direction is the main scanning direction, and the paper feed direction is the sub-scanning direction. The ink cartridge 3 may be a type that is mounted on the carriage 4 or a type that is mounted on the housing side of the printer 1 and is supplied to the recording head 2 via an ink supply tube. Hereinafter, the recording head 2 will be described.

  FIG. 2 is an exploded perspective view showing the configuration of the recording head 2 of the present embodiment, and FIG. 3 is a cross-sectional view of the recording head 2 in the longitudinal direction of the pressure chamber. The recording head 2 (head chip) has a glass electrode substrate 14 on one surface of a flow path forming substrate 12 made of silicon, and a nozzle forming substrate 13 made of silicon on the other surface of the flow path forming substrate 12. Each is arranged and laminated, and each member is joined by an adhesive to form a three-layer structure.

  The nozzle forming substrate 13 is a plate material in which a plurality of nozzle openings 15 are opened in a row at a pitch (for example, 180 dpi) corresponding to the dot formation density. The channel forming substrate 12 is subjected to anisotropic etching from its surface to form a groove portion serving as an ink channel, and the opening portion of the groove portion is blocked by the nozzle forming substrate 13. A plurality of pressure chambers 16 provided corresponding to each nozzle opening 15, a common ink chamber 17 into which ink common to each pressure chamber is introduced, and an ink supply path that communicates the common ink chamber 17 with each pressure chamber 16. A series of 18 ink flow paths are defined.

  In the flow path forming substrate 12, an ink introduction port 24 penetrating in the thickness direction of the substrate is formed at the bottom surface of the groove portion that becomes the common ink chamber 17. Further, a diaphragm 19 that functions as an elastic surface that can be elastically displaced in the head stacking direction (vertical direction in FIG. 3) is formed on the bottom surface of the groove portion that becomes each pressure chamber 16. That is, the diaphragm 19 is configured to partition at least one surface of the pressure chamber 16. A common electrode terminal 20 is formed on the flow path forming substrate 12, and since the flow path forming substrate 12 has conductivity, the diaphragm 19 functions as a common electrode. Note that an insulating layer (not shown) made of inorganic glass is provided on the surface of the flow path forming substrate 12 to which the electrode substrate 14 is bonded. In the present embodiment, the flow path forming substrate 12 is manufactured by etching a Si substrate. This point will be described in detail later.

  The electrode substrate 14 is made of borosilicate glass. This borosilicate glass has a thermal expansion coefficient similar to that of silicon. For this reason, separation between the head constituent members due to temperature changes is difficult to occur. On the surface of the electrode substrate 14 that is bonded to the flow path forming substrate 12, a recess 14 a that is shallowly etched in a tray shape is formed at a position facing the vibration plate 19 of the pressure chamber 16 corresponding to each pressure chamber 16. Is formed. Individual electrodes 21 formed by laminating thin films such as indium tin oxide (ITO) are laid on the bottom surfaces of the recesses 14a. Each individual electrode 21 includes a segment electrode 21 a extending corresponding to each pressure chamber 16 and an electrode terminal portion 21 b exposed to the outside. When the electrode substrate 14 is joined to the flow path forming substrate 12, the diaphragm 19 of each pressure chamber 16 and the segment electrode 21a of each individual electrode 21 face each other in a state where a narrow gap is formed. This gap is sealed by the sealing material 22 and is in a sealed state.

  The electrode substrate 14 is formed with an ink introduction path 23 penetrating in the substrate thickness direction. The ink introduction path 23 communicates with the ink introduction port 24 in a joined state with the flow path forming substrate 12. It is like that. For example, ink from an ink tank (not shown) provided on the printer 1 side is introduced into the common ink chamber 17 through the ink introduction path 23 and the ink introduction port 24. The ink in the common ink chamber 17 is distributed and supplied to each pressure chamber 16 through an ink supply path 18 branched from the common ink chamber 17.

  A drive voltage supply source 25 is electrically connected between the common electrode terminal 20 of the flow path forming substrate 12 and the individual electrode 21 of the electrode substrate 14. A driving voltage is applied between each individual electrode 21 and the common electrode terminal 20 by the driving voltage supply source 25. As a result, an electrostatic force is generated between the diaphragm 19 functioning as a common electrode and the individual electrode 21, and by this electrostatic force, the diaphragm 19 is elastically deformed and bent toward the individual electrode 21 side, and the surface of the segment electrode 21a Adsorb to. As a result, the volume of the pressure chamber 16 increases and ink flows into the pressure chamber 16 from the common ink chamber 17 side through the ink supply path 18. When the driving voltage from the driving voltage supply source 25 is not applied and the electrostatic force is released, the diaphragm 19 is separated from the surface of the segment electrode 21a by the elastic force and returns to the initial state. As a result, the volume of the pressure chamber 16 is rapidly reduced. As a result, a pressure fluctuation occurs in the ink in the pressure chamber 16, and a part of the ink in the pressure chamber 16 is ejected as an ink droplet from the nozzle opening 15 due to the pressure fluctuation. That is, the diaphragm 19, the common electrode terminal 20, the individual electrode 21, and the drive voltage supply source 25 function as drive means in the present invention.

  The vibration plate 19 in the recording head 2 of the present embodiment is a high-concentration p-type impurity layer, and is set to a plate thickness of 2 μm, for example. Note that boron, gallium, aluminum, and the like are impurities forming the high-concentration p-type impurity layer, but boron is generally used as an impurity forming the p-type impurity in the semiconductor field, and boron is also used in this embodiment. As an impurity. Therefore, the high concentration p-type impurity layer in the present invention is a high concentration boron doped layer.

  Next, a method for manufacturing the substrate 28 as a Si substrate that serves as a base material for manufacturing the flow path forming substrate 12 when the high concentration p-type impurity layer is a high concentration boron doped layer will be described. FIG. 4 is a sectional view of the substrate 28 and a diffusion process diagram.

First, both surfaces of a Si substrate having a (110) plane as a plane orientation are mirror-polished to produce a substrate 28 having a thickness of 180 μm (FIG. 4A). The substrate 28 is put into a thermal oxidation furnace and subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an oxygen and water vapor atmosphere to form a 1.2 μm oxide film 29 on the surface of the substrate 28 (FIG. 4B). ). Next, a resist is coated on the other surface of the substrate 28 except the one surface 30 on which the high-concentration boron-doped layer is formed, and the oxide film 29 formed on the one surface 30 is used as a protective film to form an aqueous hydrofluoric acid solution. Then, the resist coated on the other surface except for one surface 30 of the substrate 28 is removed (FIG. 4C). Here, a diffusion agent 32 in which B ₂ O _{3 serving} as a diffusion source is dispersed in an organic solvent at, for example, 3.15 wt% is applied to one surface 30 from which the oxide film 29 is removed at 2000 rpm for 1 minute. Spin coat and bake in a clean oven at 140 ° C. for 30 minutes. At this time, the thickness of the diffusing agent 32 is 1.2 μm (FIG. 4D).

Then, the substrate 28 coated with the diffusing agent 32 on one surface 30 is set in a thermal oxidation furnace, heated in an oxygen atmosphere at 600 ° C. to oxidize and remove the organic binder in the diffusing agent 32, and B _2. O ₃ is fired. Subsequently, the inside of the thermal oxidation furnace is put into a nitrogen atmosphere, the temperature is raised to 1100 ° C., the temperature is maintained for 8 hours, and boron is diffused into the substrate 28 to form the high-concentration boron doped layer 33. At this time, a boron compound 34 is formed at the interface between the diffusing agent 32 (B ₂ O ₃ ) and the high-concentration boron-doped layer 33 formed on one surface 30 (FIG. 4E).

The resist is coated on the other surface except the one surface 30 on which the high-concentration boron-doped layer 33 is formed again, and the diffusing agent 32 is removed by etching with a hydrofluoric acid aqueous solution (FIG. 4F). Here, since the boron compound 34 appearing on one surface 30 of the substrate 28 has high etching resistance and cannot be removed by wet etching, it is removed by the following means. First, after removing the resist of the substrate 28, the substrate was set 28 to a thermal oxidation furnace, oxygen and water vapor atmosphere, boron compound 34 was oxidized for 1 hour at 600 ° C., which can be etched by hydrofluoric acid aqueous solution B ₂ O Chemical change to ₃ + SiO ₂ . Since the oxidation temperature is low and diffusion does not proceed, the boron compound 34 can be removed by dry etching without being oxidized. Then, the boron compound on the diffusion surface is oxidized and further thermally oxidized in a state of chemical change to B ₂ O ₃ + SiO ₂ , thereby forming a 1.2 μm oxide film 35 on the high-concentration boron doped layer 33 side (FIG. 4). (G)). Subsequently, resist patterning for forming the pressure chamber 16, the common ink chamber 17 and the like is performed on the oxide film 29 formed on the other surface opposite to the one surface 30 of the substrate 28, and etching is performed with a hydrofluoric acid aqueous solution. The oxide film 29 is patterned. Thereafter, the resist on the substrate 28 is peeled off. In this way, the substrate 28 that is the base material of the flow path forming substrate 12 is produced (FIG. 4H).

  In the present embodiment, as described above, the method of forming the high-concentration boron-doped layer 33 by the coating method is exemplified. However, the present invention is not limited to this, and a method of performing thermal diffusion with the boron diffusion plate opposed to the Si substrate is used. It may be used.

Further, in the present embodiment, when the dopant of the substrate 28 in which the high-concentration p-type impurity is diffused is boron, the etching rate in the Si etching with alkali in the high-concentration (about 5 × 10 ¹⁹ cm ⁻³ or more) region. The flow path forming substrate 12 is manufactured by anisotropic etching by utilizing the fact that is very small. That is, the region where the diaphragm 19 is formed is the high-concentration boron doped layer 33 of the substrate 28, and when the pressure chamber 16 and the common ink chamber 17 are formed by alkali anisotropic etching, when the high-concentration boron doped layer 33 is exposed. The diaphragm 19 of the flow path forming substrate 12 is manufactured to have a plate thickness of 2 μm, for example, by a so-called etching stop technique in which the etching rate becomes extremely small. Hereinafter, a manufacturing method of the diaphragm 19 and the pressure chamber 16 will be described.

  FIG. 5 is an etching process diagram that constitutes the manufacturing process of the flow path forming substrate 12, and FIG. 6 shows the concentration and etching surface of the potassium hydroxide aqueous solution used in the first etching process (the etching surface 40 when the etching is stopped). Is a graph showing the relationship between the surface roughness (PV) and the maximum height of the convex etching residue.

  The flow path forming substrate 12 in the recording head 2 of the present embodiment has a high-concentration boron doped layer 33 formed as a high-concentration p-type impurity layer on one surface 30 of a substrate 28 that is a Si substrate, and is opposite to the one surface 30. The first etching step is performed from the first surface (the other surface 31) to the middle of the substrate 28 with an etching solution whose concentration is adjusted to 30 wt% or less. At least one of the pressure chamber 16 and the pressure chamber 16 is performed by performing a second etching step in which etching is performed with an etching solution having a lower concentration than the etching solution used in the first etching step until the concentration boron doped layer 33 is reached. And a diaphragm 19 that divides the surface. Note that the etching solution of this embodiment is a potassium hydroxide aqueous solution generally used for etching a Si substrate. Further, “30 wt% or less” does not include 0 wt%.

  Here, in the present embodiment, in order to suppress the maximum height of the convex etching residue on the etching surface 40 of the diaphragm 19, the concentration of the etching solution (potassium hydroxide aqueous solution) used in the first etching step is set how. As shown in FIG. 6, from the experimental result of the relationship between the concentration of the potassium hydroxide aqueous solution and the surface roughness (PV) of the etching surface 40 and the maximum height of the convex etching residue, as shown in FIG. It stipulates. This is because the concentration of the potassium hydroxide aqueous solution used for etching and the generation of the convex etching residue are prevented in order to prevent the generation of the convex etching residue generated on the etching surface located on the outer periphery of the Si substrate (Si wafer) by etching. Since it has been found that there is a causal relationship, the experiment was conducted to determine the range of the concentration of the aqueous potassium hydroxide solution in which convex etching residue hardly occurs while keeping the surface roughness of the etched surface small. Specifically, in a 35 wt% potassium hydroxide aqueous solution used in the conventional etching process, the surface roughness PV = 0.10 μm of the etching surface 40 (bottom surface of the pressure chamber 16) at the time of etching stop. Thus, the thickness unevenness of the diaphragm 19 can be suppressed, but the maximum height of the remaining convex etching is about 3.00 μm with respect to the diaphragm 19 having a thickness of 2.00 μm. The rigidity of the is not constant. Therefore, the elastic deformation of the vibration plate 19 is not uniform, and the ejection characteristics of the recording head 2 are unstable. Then, as shown in FIG. 6, when the concentration of this potassium hydroxide aqueous solution is higher than 30 wt%, the maximum height of the remaining convex etching becomes 1.00 μm or more at which the ejection characteristics of the recording head 2 become unstable. I understand that. Therefore, by adjusting the potassium hydroxide aqueous solution used in the first etching step to a concentration of 30 wt% or less, the etching surface 40 of the diaphragm 19 has a rough surface with a surface roughness PV = 0.20 μm or less, and a convex etching. It was found that the remaining maximum height could be 0.35 μm or less. Then, when the ejection characteristic inspection was performed using the recording head 2 provided with the diaphragm 19 manufactured under this density condition, it was confirmed that the ejection characteristic of the recording head 2 was stable. Thereby, in the recording head 2 in the present embodiment, the surface on the pressure chamber side of the vibration plate 19 is a rough surface having a surface roughness PV = 0.20 μm or less, and the maximum height of the remaining convex etching is 0.35 μm or less. Is a good product.

By the way, the potassium hydroxide aqueous solution used in the first etching step can suppress the occurrence of the convex etching residue as the concentration is lowered. However, the concentration is not simply reduced, as shown in FIG. In particular, when the concentration is 25 wt% or less, the etching surface 40 has a surface roughness PV = 0.30 μm and the rigidity in the diaphragm 19 is not constant due to thickness unevenness. Is not uniform, the ejection characteristics of the recording head 2 become unstable. Therefore, the concentration of the etchant (potassium hydroxide aqueous solution) in the first etching step of the present invention is a balance between the surface roughness of the etched surface and the maximum height of the convex etching residue in consideration of the elastic deformation characteristics of the diaphragm. Is important, and it is desirable to set it to 25 wt% or more and 30 wt% or less from the above experimental results.
In particular, in consideration of individual product variations, in mass production, it is preferable to set the concentration of the etching solution to 27 to 28.5 wt% at which almost no convex etching residue occurs. In the following, the etching process will be described by taking as an example a potassium hydroxide aqueous solution having a concentration of 28.5 wt%, which is considered to have the best balance between the surface roughness of the etched surface and the maximum height of the convex etching residue by experiment. .

  As shown in FIG. 5A, the substrate 28 has a high-concentration boron-doped layer 33 formed on one surface 30, and the pressure chamber 16 and the common ink chamber 17 on the other surface 31 opposite to the one surface 30. If the resist patterning is performed to form the surface of the substrate 28, for example, an etching solution made of an aqueous potassium hydroxide solution adjusted to a temperature of 80 ° C. and a concentration of 28.5 wt% is used. That is, anisotropic etching is performed immediately before reaching the high-concentration boron-doped layer 33 (remaining about 10 μm: etching surface 38) (first etching step: FIG. 5B).

  Next, potassium hydroxide having a concentration lower than that of the 28.5 wt% potassium hydroxide aqueous solution used in the first etching step until the high-concentration boron doped layer 33 is reached from the etching surface 38 etched in the first etching step. A second etching step of etching with an aqueous solution is performed. Here, in the low-concentration potassium hydroxide aqueous solution in the second etching step, the concentration is set as in the conventional case. That is, considering the surface roughness (about 10 μm) of the etched surface in the first etching step and the thickness accuracy (within ± 0.35 μm) of the diaphragm 19 at the time of etching stop, the concentration and selection of the potassium hydroxide aqueous solution are selected. From the relationship of the ratio, the concentration of the potassium hydroxide aqueous solution is desirably set to 10 wt% or less. When the concentration is 0.5 wt% or less, the etching ability becomes unstable and impractical, so the concentration of the etching solution (potassium hydroxide aqueous solution) used in the second etching step in this embodiment is set to 0. It is set to 5 to 10 wt%. If the concentration range is 0.5 to 10 wt%, the etching rate can be extremely reduced by the high-concentration p-type impurity layer (high-concentration boron doped layer 33), and the etching can be surely stopped. Experimentally, it has been found that it is preferable to adjust the concentration of the etching solution used in the second etching step to 2.5%.

  Therefore, in the present embodiment, when the first etching step is completed, as shown in FIGS. 5B to 5C, for example, hydroxylation adjusted to a temperature of 80 ° C. and a concentration of 2.5 wt%. Etching is continued from the etching surface 38 in the first etching step using an etching solution made of an aqueous potassium solution, and the etching is stopped when the high concentration boron doped layer 33 is reached. Thereby, the pressure chamber 16 in the flow path forming substrate 12 and the diaphragm 19 having a plate thickness of 2 μm constituted by the high-concentration boron doped layer 33 can be formed.

  Finally, after the etching process of the substrate 28, the oxide films 29 and 35 remaining on the substrate 28 are removed by etching using an aqueous hydrofluoric acid solution (FIG. 5D), and then the entire surface of the substrate 28 is oxidized by thermal oxidation. A film (not shown) is formed with a thickness of 0.1 μm, and the flow path forming substrate 12 in the recording head 2 is manufactured.

  In this way, etching is performed with a potassium hydroxide aqueous solution whose concentration is adjusted to 30 wt% or less from the surface opposite to the one surface 30 on which the high-concentration boron-doped layer 33 of the substrate 28 which is a Si substrate is formed to the middle of the substrate 28. After performing the first etching step, the aqueous potassium hydroxide solution having a concentration lower than that of the aqueous potassium hydroxide solution used in the first etching step until reaching the high-concentration boron doped layer 33 from the etching surface 38 of the first etching step. When the pressure chamber 16 and the vibration plate 19 are formed by performing the second etching step in which etching is performed at the surface, the surface roughness of the surface on the pressure chamber 16 side of the vibration plate 19 in the flow path forming substrate 12 can be reduced. The maximum height of the convex etching residue on the surface can be suppressed. Specifically, the surface roughness (PV) of the surface of the diaphragm 19 on the pressure chamber 16 side becomes a rough surface of 0.2 μm or less, thickness unevenness can be suppressed, and the thickness accuracy of the diaphragm 19 is improved. Can do. In addition, the maximum height of the convex etching residue generated on the surface of the diaphragm 19 on the pressure chamber 16 side can be set to 0.35 μm or less, and uneven thickness of the diaphragm can be suppressed. From the above, the thickness of the diaphragm 19 can be made highly accurate, and the maximum height of the convex etching residue of the diaphragm 19 can also be suppressed to an allowable range or less. Can be constant. Therefore, the elastic deformation of the diaphragm 19 can be made uniform, and the ejection characteristics of the recording head 2 can be made more stable. Furthermore, in the manufacturing process of the recording head 2, it can contribute to the improvement of the yield. Further, when the concentration of the potassium hydroxide aqueous solution in the first etching step is 27 to 28.5 wt%, the convex etching residue hardly occurs on the surface of the diaphragm 19 on the pressure chamber 16 side. The rigidity in the diaphragm 19 can be made more constant. Thereby, the ejection characteristics of the recording head 2 can be further stabilized. In the printer 1 including the recording head 2 manufactured by the above manufacturing method, the image quality of the recorded image can be stabilized.

  Further, when the concentration of the potassium hydroxide aqueous solution used in the second etching step is set to 0.5 to 10 wt%, the etching rate is rapidly increased in the high concentration boron doped layer 33 when the high concentration boron doped layer 33 is exposed by the etching. Therefore, the etching can be surely stopped. Therefore, the diaphragm 19 composed of the high-concentration boron doped layer 33 can be formed with higher accuracy. In particular, when the above concentration is set to 2.5 wt%, the effect becomes remarkable.

  In the above description, the ink jet recording head 2 is described as an example of the liquid ejecting head mounted on the liquid ejecting apparatus. However, the present invention can also be applied to other liquid ejecting heads. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, an FED (surface emitting display), a biochip (biochemical element) The present invention can also be applied to bioorganic matter ejecting heads and the like used in the production of

FIG. 3 is a perspective view illustrating a basic configuration of a printer. FIG. 3 is an exploded perspective view illustrating the configuration of a recording head to which the invention is applied. FIG. 4 is a cross-sectional view of the recording head in the longitudinal direction of the pressure chamber. It is sectional drawing of a board | substrate, and is a diffusion process figure. FIG. 5 is an etching process diagram constituting a manufacturing process of a flow path forming substrate in the recording head of the present invention. It is a graph which shows the relationship between the density | concentration of the potassium hydroxide aqueous solution used for a 1st etching process, the surface roughness of an etching surface, and the maximum height of a convex etching residue.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Recording head, 3 ... Ink cartridge, 4 ... Carriage, 5 ... Platen, 6 ... Recording paper, 7 ... Carriage moving mechanism, 8 ... Paper feed mechanism, 12 ... Channel formation board, 13 ... Nozzle formation Substrate, 14 ... electrode substrate, 14a ... recess, 15 ... nozzle opening, 16 ... pressure chamber, 17 ... common ink chamber, 18 ... ink supply path, 19 ... diaphragm, 20 ... common electrode terminal, 21 ... individual electrode, 21a ... segment electrode, 21b ... electrode terminal, 22 ... sealing material, 23 ... ink introduction path, 24 ... ink introduction port, 25 ... drive voltage supply source, 28 ... substrate, 29 ... oxide film, 30 ... one surface, 31 ... The other surface, 32 ... Diffusing agent, 33 ... High-concentration boron doped layer, 34 ... Boron compound, 35 ... Oxide film, 38 ... Etching surface, 40 ... Etching surface

Claims (7)

A flow path forming substrate having a pressure chamber communicating with a nozzle opening for ejecting liquid droplets and a diaphragm that partitions at least one surface of the pressure chamber, and changing the volume of the pressure chamber by deforming the diaphragm. A liquid ejecting head manufacturing method comprising a driving unit, wherein the flow path forming substrate is an Si substrate,
A high-concentration p-type impurity layer is formed on one surface of the Si substrate, and etching is performed with an etching solution whose concentration is adjusted to 30 wt% or less from the surface opposite to the surface to the middle of the Si substrate. And then etching is performed with an etchant having a lower concentration than the etchant used in the first etching step until the high-concentration p-type impurity layer is reached after the etching in the first etching step. A method of manufacturing a liquid jet head, wherein the pressure chamber of the flow path forming substrate and the vibration plate are formed by performing the etching step 2.   The method of manufacturing a liquid jet head according to claim 1, wherein the etching liquid is an aqueous potassium hydroxide solution.   3. The method of manufacturing a liquid jet head according to claim 1, wherein the concentration of the etchant used in the second etching step is 0.5 to 10 wt%.   The method of manufacturing a liquid jet head according to claim 1, wherein the high-concentration p-type impurity layer is a high-concentration boron-doped layer.   5. A pressure chamber communicating with a nozzle opening for discharging droplets and at least one surface of the pressure chamber are partitioned, and the Si substrate is etched by the method of manufacturing a liquid jet head according to claim 1. A liquid ejecting apparatus having a liquid ejecting head including a flow path forming substrate having a vibration plate formed by the operation and a driving unit that changes the volume of the pressure chamber by deforming the vibration plate.   The liquid ejecting apparatus according to claim 5, wherein a surface roughness (PV) of a surface on the pressure chamber side of the diaphragm is a rough surface of 0.2 μm or less.   7. The liquid ejecting apparatus according to claim 5, wherein a maximum height of a convex etching residue generated on the pressure chamber side surface of the vibration plate is 0.35 μm or less. 8.

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