JP3846552B2 - Method for manufacturing ink jet recording head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an inkjet in which a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is constituted by a diaphragm, and a piezoelectric element is provided through the diaphragm, and ink droplets are ejected by displacement of the piezoelectric element. The present invention relates to a method for manufacturing a recording head.
[0002]
[Prior art]
A part of the pressure generation chamber communicating with the nozzle opening for discharging ink droplets is constituted by a vibration plate, and the vibration plate is deformed by a piezoelectric element to pressurize the ink in the pressure generation chamber to discharge ink droplets from the nozzle opening. Two types of ink jet recording heads have been put into practical use: those using a piezoelectric actuator in a longitudinal vibration mode in which a piezoelectric element extends and contracts in the axial direction, and those using a piezoelectric actuator in a flexural vibration mode.
[0003]
The former can change the volume of the pressure generation chamber by bringing the end face of the piezoelectric element into contact with the vibration plate, and it is possible to manufacture a head suitable for high-density printing, while the piezoelectric element is arranged in an array of nozzle openings. There is a problem that the manufacturing process is complicated because a difficult process of matching the pitch into a comb-like shape and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are necessary.
[0004]
On the other hand, the latter can flexibly vibrate, although a piezoelectric element can be built on the diaphragm by a relatively simple process of sticking a green sheet of piezoelectric material according to the shape of the pressure generation chamber and firing it. There is a problem that a certain amount of area is required for the use of, and high-density arrangement is difficult.
[0005]
On the other hand, in order to eliminate the inconvenience of the latter recording head, a uniform piezoelectric material layer is formed by a film forming technique over the entire surface of the diaphragm as seen in Japanese Patent Laid-Open No. 5-286131. A material in which a piezoelectric layer is formed so that a material layer is cut into a shape corresponding to a pressure generation chamber by a lithography method and is independent for each pressure generation chamber has been proposed.
[0006]
This eliminates the need to affix the piezoelectric element to the diaphragm, so that not only can the piezoelectric element be created by a precise and simple technique called lithography, but also the thickness of the piezoelectric element can be reduced. There is an advantage that high-speed driving is possible.
[0007]
[Problems to be solved by the invention]
However, in such an ink jet recording head, when the pressure generating chambers are arranged at a high density, the partition walls between the pressure generating chambers become thin due to a decrease in the thickness of the partition walls. There is a problem that crosstalk occurs.
[0008]
On the other hand, in the piezoelectric actuator in the longitudinal vibration mode, a structure is considered in which a wide portion is provided on the diaphragm side of the pressure generating chamber, and the width of the pressure generating chamber in other portions is reduced to increase the thickness of the partition wall. However, in this case, there is a problem that workability and accuracy are low because operations such as processing and bonding of the wide portion of the pressure generation chamber are required.
[0009]
SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a method for manufacturing an ink jet recording head capable of reducing the manufacturing cost by reducing the crosstalk between the pressure generating chambers with high density and simplifying the manufacturing process. Is an issue.
[0032]
[Means for Solving the Problems]
A first aspect of the present invention that solves the above-described problem includes a flow path forming substrate in which a pressure generation chamber communicating with a nozzle opening is defined, and a film is formed on one side of the flow path forming substrate via a diaphragm. And a method of manufacturing an ink jet recording head having a lower electrode made of a thin film formed by a lithography method, a piezoelectric element made of a piezoelectric layer and an upper electrode, and a step of forming a pressure generating chamber in the flow path forming substrate; A porous silicon layer or a hydrogen ion layer containing hydrogen ions provided on at least one surface side; and a bonding layer made of single crystal silicon or silicon oxide provided on the porous silicon layer or hydrogen ion layer. Bonding the bonding layer side of the diaphragm base material to the flow path forming substrate without an adhesive, and removing the porous silicon layer or the hydrogen ion layer of the diaphragm base material Forming the diaphragm by peeling a composite layer and a region other than the bonding layer; and laminating and patterning the lower electrode film, the piezoelectric film, and the upper electrode film on the diaphragm, And a step of forming the ink jet recording head.
[0033]
In the first aspect, the bonding layer can be easily bonded onto the flow path forming substrate, and the manufacturing cost can be reduced.
[0034]
In a second aspect of the present invention, the flow path forming substrate has a flow path forming layer made of single crystal silicon in which the pressure generating chamber is formed, and the diaphragm base material is bonded to the flow path forming layer. In the method of manufacturing an ink jet recording head according to the first aspect,
[0035]
According to the second aspect, a highly accurate pressure generating chamber can be formed, and the flow path forming substrate and the diaphragm base material can be easily and reliably joined.
[0036]
According to a third aspect of the present invention, the diaphragm base material is formed of an SOI substrate having silicon layers made of single crystal silicon on both sides of the insulator layer, and the bonding layer includes the insulator layer and one of the silicon layers. The method of manufacturing an ink jet recording head according to the first or second aspect is characterized by comprising:
[0037]
In the third aspect, the region other than the bonding layer of the diaphragm base material can be easily removed.
[0038]
According to a fourth aspect of the present invention, there is provided the ink jet recording head manufacturing method according to the first or second aspect, wherein the bonding layer is made of single crystal silicon in which boron is diffused.
[0039]
In the fourth aspect, by using a bonding layer made of single crystal silicon in which boron is diffused, a region other than the bonding layer of the vibration plate base material can be easily and reliably removed, and the vibration plate can be easily formed.
[0040]
According to a fifth aspect of the present invention, in the ink jet type according to the first or second aspect, the diaphragm base material is made of single crystal silicon having a pn junction, and the bonding layer is n-type single crystal silicon. A method of manufacturing a recording head.
[0041]
In the fifth aspect, by using a bonding layer made of n-type single crystal silicon, a region other than the bonding layer of the vibration plate base material can be easily and surely removed to easily form the vibration plate.
[0042]
According to a sixth aspect of the present invention, in the first or second aspect, the diaphragm base material is made of two layers of single crystal silicon having different impurity concentrations, and the bonding layer is made of a low concentration layer. The method is for manufacturing an ink jet recording head.
[0043]
In the sixth aspect, by using low-concentration single crystal silicon for the bonding layer, it is possible to easily and surely remove the region other than the bonding layer of the vibration plate base material and easily form the vibration plate.
[0044]
According to a seventh aspect of the present invention, in the step of bonding the diaphragm base material to the flow path forming substrate, the two are bonded by direct bonding or normal temperature bonding. In the inkjet recording head manufacturing method.
[0045]
In the seventh aspect, the diaphragm base material and the flow path forming substrate can be easily and reliably joined by direct joining or room temperature joining.
[0046]
An eighth aspect of the present invention is the ink jet recording head according to the first or second aspect, wherein in the step of joining the diaphragm base material to the flow path forming substrate, both are joined by anodic bonding. In the manufacturing method.
[0047]
In the eighth aspect, the diaphragm base material and the flow path forming substrate can be easily and reliably bonded by anodic bonding.
[0048]
According to a ninth aspect of the present invention, in the step of forming the diaphragm, after the flow path forming substrate is covered with a protective layer, the region other than the bonding layer of the diaphragm base material is removed. The method of manufacturing an ink jet recording head according to any one of the first to eighth aspects.
[0049]
In the ninth aspect, when the region other than the bonding layer of the diaphragm base material is removed, the flow path forming substrate is not removed, and a highly accurate diaphragm can be formed.
[0050]
According to a tenth aspect of the present invention, in the step of forming the pressure generating chamber, the pressure generating chamber is formed without penetrating the flow path forming substrate. In the inkjet recording head manufacturing method.
[0051]
In the tenth aspect, the rigidity of the partition walls defining the pressure generation chamber can be improved to prevent crosstalk between the pressure generation chambers, and the ink ejection characteristics can be improved.
[0052]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments.
[0053]
(Embodiment 1)
FIG. 1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a view showing a cross-sectional structure in the longitudinal direction of one pressure generating chamber of the ink jet recording head.
[0054]
As shown in the figure, the flow path forming substrate 10 in which the pressure generating chamber 12 is formed is made of, for example, a silicon single crystal substrate having a thickness of 150 μm to 1 mm, and the surface layer portion on one side thereof is anisotropically etched. Thus, a pressure generation chamber 12 partitioned by a plurality of partition walls 11 is formed.
[0055]
In addition, at one end in the longitudinal direction of each pressure generation chamber 12, an ink communication portion 13, which is a relay chamber for connecting a reservoir 15 and a pressure generation chamber 12, which will be described later, is narrower than the pressure generation chamber 12. 14 to communicate with each other. The ink communication portion 13 and the narrow portion 14 are formed by anisotropic etching together with the pressure generating chamber 12. The narrow portion 14 is for controlling the flow of ink in and out of the pressure generating chamber 12.
[0056]
For this anisotropic etching, either wet etching or dry etching may be used, but the pressure generating chamber 12 is formed shallow by etching the silicon single crystal plate halfway in the thickness direction (half etching). The depth can be adjusted by the etching time of half etching.
[0057]
In this embodiment, the ink communication portion 13 is provided for each pressure generation chamber 12. However, the present invention is not limited to this. For example, the ink communication portion 13 may be shared by the pressure generation chambers 12. In this case, the ink communication part 13 may constitute a part of the reservoir 15 described later.
[0058]
On the other hand, on the other surface side of the flow path forming substrate 10, a reservoir 15 that communicates with each ink communication portion 13 and supplies ink to each pressure generation chamber 12 is formed. The reservoir 15 is formed, for example, by anisotropic etching from the other surface side of the flow path forming substrate 10 using the protective film 55b as a mask.
[0059]
An elastic film 50 made of single crystal silicon or silicon oxide and having a thickness of approximately 1 μm or less is bonded to the pressure generating chamber 12 side of the flow path forming substrate 10 without using an adhesive. . The elastic membrane 50 constitutes one wall surface of the pressure generating chamber 12 on one surface thereof. In this embodiment, the elastic film 50 is made of silicon oxide (SiO 2 ₂ The elastic film 50 and the flow path forming substrate 10 are bonded by anodic bonding as will be described in detail later. A protective film 55a made of silicon oxide is formed on the bonding surface of the flow path forming substrate 10 with the elastic film 50. This protective film 55a is used as a mask when the pressure generating chamber 12 is formed on the flow path forming substrate 10, and is also used when the elastic film 50 and the flow path forming substrate 10 are anodic bonded.
[0060]
In a region opposite to each pressure generating chamber 12 on the elastic film 50, a lower electrode film 60 having a thickness of, for example, about 0.5 μm, and a piezoelectric layer 70 having a thickness of, for example, about 1 μm, The upper electrode film 80 having a thickness of, for example, about 0.1 μm is laminated and formed by the process described later to constitute the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In addition, here, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300 and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for convenience of a drive circuit and wiring. In either case, a piezoelectric active part is formed for each pressure generating chamber. Here, the piezoelectric element 300 and the elastic film that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In the present embodiment, the elastic film 50 and the lower electrode film 60 are diaphragms.
[0061]
In addition, on the piezoelectric element 300 side of the flow path forming substrate 10, in this embodiment, on the elastic film 50 and the lower electrode film 60, a space that does not hinder the movement is secured in a region facing the piezoelectric element 300. The sealing plate 20 having the piezoelectric element holding portion 22 that can seal the space is joined.
[0062]
In the present embodiment, the sealing plate 20 is provided with nozzle openings 21 communicating with the pressure generating chambers 12 and also serves as a nozzle plate. The nozzle opening 21 and the pressure generating chamber 12 are communicated with each other via a nozzle communication hole 51 provided by removing the elastic film 50 and the lower electrode film 60.
[0063]
Here, the manufacturing process of the ink jet recording head of the present embodiment, particularly the process of forming the pressure generating chamber 12 in the flow path forming substrate 10 and the process of forming the piezoelectric element 300 in the region corresponding to the pressure generating chamber 12. explain. 3 to 5 are cross-sectional views of the pressure generating chamber 12 in the longitudinal direction.
[0064]
First, as shown in FIG. 3A, a silicon single crystal substrate wafer to be the flow path forming substrate 10 is thermally oxidized in a diffusion furnace at about 1100 ° C. to form protective films 55a and 55b made of silicon oxide. At the same time, an opening 12a is formed in a region of the protective film 55a on one side where the pressure generating chamber 12 is to be formed.
[0065]
Next, as shown in FIG. 3B, the pressure generating chamber 12, the ink communication portion 13, and the narrow portion 14 are formed by anisotropically etching the flow path forming substrate 10 using the protective film 55a as a mask.
[0066]
Next, as shown in FIG. 3C, an elastic film base material 150 made of single crystal silicon having a thickness of, for example, 220 μm is bonded to the surface of the flow path forming substrate 10 where the pressure generating chamber 12 opens. The elastic film base material 150 has a silicon oxide layer 151 made of silicon oxide formed by, for example, thermal oxidation, TEOS-CVD method, wet oxidation, or the like on the joint surface with the flow path forming substrate 10.
[0067]
This silicon oxide layer 151 becomes an elastic film 50 by removing a region other than the silicon oxide layer 151 of the elastic film base material 150 after bonding to the flow path forming substrate 10 in a later step. It is formed with a thickness.
[0068]
Moreover, the joining method of the flow path forming substrate 10 and the elastic film base material 150 is not particularly limited as long as it can be joined without using an adhesive, and examples thereof include direct joining, room temperature joining, and anodic joining. In this embodiment, both were joined by anodic bonding.
[0069]
Specifically, in a state where the protective film 55a of the flow path forming substrate 10 made of a silicon single crystal substrate whose opposite surfaces are polished into a mirror surface and the silicon oxide layer 151 of the elastic film base material 150 are in contact with each other, The temperature is raised to near 450 ° C., and a potential of 200 to 1000 V is applied to both substrates. At this time, positive H in the protective film 55a made of silicon oxide and the silicon oxide layer 151 is obtained. ⁺ Since ions easily move in silicon oxide, they are attracted by a negative electric field and reach the surfaces of the protective film 55a and the silicon oxide layer 151, respectively. On the other hand, the negative ions remaining in the protective film 55a and the silicon oxide layer 151 form a space charge layer on the bonding surface of both, and strong suction is performed between the flow path forming substrate 10 and the elastic film base material 150. When force is generated, both are chemically bonded.
[0070]
When the elastic film base material 150 and the flow path forming substrate 10 are bonded by anodic bonding in this way, if there is a small amount of dust or dirt on the surface, the portion is not bonded and a void layer is formed at the bonding interface. Will be.
[0071]
Next, as shown in FIG. 3D, an excessive region of the elastic film base material 150 is removed. In the present embodiment, only the region other than the silicon oxide layer 151, that is, single crystal silicon is removed.
[0072]
In this embodiment, this single crystal silicon is removed by wet etching using an alkaline aqueous solution such as KOH.
[0073]
In this way, by removing the region other than the silicon oxide layer 151 of the elastic film base material 150, the silicon oxide layer 151 remaining on the flow path forming substrate 10 becomes the elastic film 50.
[0074]
According to such a method, the elastic film 50 made of a thin film of approximately 1 μm or less can be bonded to the flow path forming substrate 10 in which the shallow pressure generating chamber 12 is formed without using an adhesive, thereby simplifying the manufacturing process. Manufacturing cost can be reduced.
[0075]
The method for removing single crystal silicon is not particularly limited as long as only the silicon oxide layer 151 can remain, such as etching or polishing, and the single crystal silicon may be peeled off.
[0076]
For example, a porous silicon layer is provided at the boundary between the silicon oxide layer 151 and the single crystal silicon of the elastic film base material 150, and the porous silicon layer is bonded to the flow path forming substrate 10 and the elastic film base material 150. By removing the layer by etching or the like, the single crystal silicon can be easily separated from the silicon oxide layer 151. Such an elastic film base material 150 is formed by forming a porous silicon layer on the surface of the elastic film base material 150 made of single crystal silicon by anodizing, and forming a thin silicon layer thereon by epitaxial growth. It can be formed by oxidizing the surface.
[0077]
Further, for example, a hydrogen ion layer in which hydrogen ions are implanted is provided between the single crystal silicon of the elastic film base material 150 and the silicon oxide layer 151, and the flow path forming substrate 10 and the elastic film base material 150 are joined together. Single crystal silicon can be easily peeled from the silicon oxide layer 151 by heating to 500 ° C. to 600 ° C.
[0078]
Thus, if the single crystal silicon of the elastic film base material 150 is removed by peeling, the peeled single crystal silicon can be reused, and the manufacturing cost can be reduced.
[0079]
Next, the piezoelectric element 300 is formed on the elastic film 50 corresponding to each pressure generating chamber 12.
[0080]
As a step of forming the piezoelectric element 300, first, as shown in FIG. 4A, the lower electrode film 60 is formed over the entire surface of the flow path forming substrate 10 on the pressure generating chamber 12 side by sputtering and has a predetermined shape. The lower electrode film 60 is formed by patterning. As a material of the lower electrode film 60, platinum, iridium or the like is suitable. This is because a piezoelectric layer 70 described later formed by sputtering or sol-gel method needs to be crystallized by firing at a temperature of about 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation. Because. That is, the material of the lower electrode film 60 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere, particularly when lead zirconate titanate (PZT) is used as the piezoelectric layer 70. It is desirable that the conductivity change due to diffusion of lead oxide is small, and platinum and iridium are preferable for these reasons.
[0081]
Next, as shown in FIG. 4B, a piezoelectric layer 70 is formed. For example, in the present embodiment, a so-called sol-gel method is obtained in which a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied and dried to be gelled, and further baked at a high temperature to obtain a piezoelectric layer 70 made of metal oxide Formed using. As a material of the piezoelectric layer 70, a PZT material is suitable when used for an ink jet recording head. The method for forming the piezoelectric layer 70 is not particularly limited. For example, the piezoelectric layer 70 may be formed by a spin coating method such as a sputtering method or a MOD method (organic metal thermal coating decomposition method).
[0082]
Further, after forming a lead zirconate titanate precursor film by a sol-gel method, sputtering method, MOD method or the like, a method of crystal growth at a low temperature by a high pressure treatment method in an alkaline aqueous solution may be used.
[0083]
In any case, the piezoelectric layer 70 thus formed has crystals preferentially oriented unlike the bulk piezoelectric body, and in this embodiment, the piezoelectric layer 70 is formed in a columnar shape. Has been. Note that the preferential orientation refers to a state in which the orientation direction of the crystal is not disordered and a specific crystal plane is oriented in a substantially constant direction. A columnar thin film refers to a state in which substantially cylindrical crystals are aggregated over the surface direction with the central axis substantially coincided with the thickness direction to form a thin film. Of course, it may be a thin film formed of preferentially oriented granular crystals. Note that the thickness of the piezoelectric layer manufactured in this way in the thin film process is generally 0.2 to 5 μm.
[0084]
Next, as shown in FIG. 4C, an upper electrode film 80 is formed. The upper electrode film 80 only needs to be a highly conductive material, and many metals such as aluminum, gold, nickel, and platinum, conductive oxides, and the like can be used. In this embodiment, the platinum film is formed by sputtering.
[0085]
Next, as shown in FIG. 4D, the piezoelectric element 300 is patterned by etching only the piezoelectric layer 70 and the upper electrode film 80. In the present embodiment, simultaneously, the nozzle communication hole 51 is formed by patterning the elastic film 50 and the lower electrode film 60 in the vicinity of the end of the pressure generating chamber 12 on the opposite side to the ink communication part 13 in the longitudinal direction.
[0086]
Next, as shown in FIG. 5A, the lead electrode 90 is formed over the entire surface of the flow path forming substrate 10 and is patterned for each piezoelectric element 300. A lead electrode 90 extending on the elastic film 50 is formed.
[0087]
Next, as shown in FIG. 5 (b), the region to be the reservoir 15 of the protective film 55b provided on the surface of the flow path forming substrate 10 opposite to the pressure generating chamber 12 is removed by patterning to open the opening. 56, and the reservoir 15 is formed by anisotropically etching, for example, wet etching, the flow path forming substrate 10 until the ink communication portion 13 is reached from the opening 56.
[0088]
The pressure generation chamber 12 and the piezoelectric element 300 are formed by the above process.
[0089]
Thereafter, the sealing plate 20 is bonded on the piezoelectric element 300 side of the flow path forming substrate 10, in this embodiment, on the lower electrode film 60 and the elastic film 50.
[0090]
The ink jet recording head of this embodiment manufactured in this way takes in ink from an external ink supply means (not shown) into the reservoir 15 and fills the interior from the reservoir 15 to the nozzle opening 21 with the ink. In accordance with the recording signal output from the wiring, a voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generation chamber 12, and the elastic film 50, the lower electrode film 60, and the piezoelectric layer 70 are moved. By deflecting and deforming, the pressure in each pressure generating chamber 12 is increased and ink droplets are ejected from the nozzle openings 21.
[0091]
By forming the pressure generating chamber 12 without penetrating the flow path forming substrate 10 in this way, the rigidity of the partition wall 11 can be improved. Even if the pressure generating chambers 12 are arranged at a high density, the cross between the pressure generating chambers 12 is increased. Talk can be prevented.
[0092]
In the present embodiment, each pressure generating chamber 12 and the reservoir 15 are communicated with each other via the ink communicating portion 13 and the narrowed portion 14, but the present invention is not limited to this. For example, as shown in FIG. As described above, the pressure generating chambers 12 and the reservoir 15 may be directly communicated with each other.
[0093]
In the present embodiment, the narrow portion 14 is formed with a width narrower than that of the pressure generation chamber 12 to control the inflow and outflow of ink in the pressure generation chamber 12, but the present invention is not limited to this. As shown in FIG. 6 (b), the narrow portion 14A having the same width as the pressure generating chamber 12 and the adjusted depth may be used.
[0094]
(Embodiment 2)
FIG. 7 is a cross-sectional view in the longitudinal direction of the pressure generating chamber showing the method of manufacturing the ink jet recording head according to the second embodiment.
[0095]
The present embodiment is an example in which the elastic film 50A is made of single crystal silicon in which impurities are diffused.
[0096]
Here, a method of providing the elastic film 50A in this way will be described in detail. In addition, the overlapping description is abbreviate | omitted about the process similar to the manufacturing method of Embodiment 1 mentioned above.
[0097]
First, as shown in FIG. 7A, the pressure generating chamber 12 is formed in the flow path forming substrate 10 by the same process as that of the first embodiment described above.
[0098]
Next, as shown in FIG. 7B, the elastic film base material 150 </ b> A is joined to the flow path forming substrate 10 in which the pressure generation chamber 12 is formed.
[0099]
In this embodiment, the elastic film base material 150A is made of single crystal silicon, and has an impurity layer 151A in which impurities are diffused on the joint surface with the flow path forming substrate 10. In this embodiment, the impurity layer 151A can be provided, for example, by doping boron on the surface of single crystal silicon or epitaxially forming single crystal silicon in which boron is diffused on the surface of single crystal silicon.
[0100]
And the joining method of 150 A of elastic film base materials in which the impurity layer 151A was formed in this way and the flow-path formation board | substrate 10 is not specifically limited, For example, direct joining or normal temperature joining etc. can be mentioned. In this embodiment, both were joined by direct joining.
[0101]
Specifically, the joining surface of the flow path forming substrate 10 and the elastic film base material 150A is polished to a mirror surface, the surface is washed to remove dust and dirt and dried, and the surfaces of each other are cleaned in a clean atmosphere. Both are bonded by bringing them into contact.
[0102]
When the elastic film base material 150A and the flow path forming substrate 10 are bonded by direct bonding, it is difficult to match each crystal lattice, and a crystal lattice mismatch surface is formed at the bonding interface. Further, when bonding between the crystal lattices with a precision of 1 degree or less is achieved, the crystal lattices are connected at the bonding interface, and continuity similar to that of the epitaxial layer is maintained, but a transition surface is formed. Further, a void layer may be formed at the bonding interface as in the first embodiment.
[0103]
Next, as shown in FIG. 7C, an excessive region of the elastic film base material 150A is removed. In the present embodiment, only the region other than the impurity layer 151A, that is, the single crystal silicon on the other side is removed. In this embodiment, single crystal silicon was removed by wet etching with KOH.
[0104]
Here, in the wet etching with KOH, the etching speed of the impurity layer 151A in which boron is diffused is reduced by the fourth power of the ratio of the boron concentration as compared with the single crystal silicon region. It can be removed by etching, leaving only the impurity layer 151A.
[0105]
In the present embodiment, after forming only the impurity layer 151A on the flow path forming substrate 10 by such wet etching, the surface of the impurity layer 151A is smoothed by electrolytic polishing to form the elastic film 50A.
[0106]
The subsequent steps of forming the piezoelectric element 300, the reservoir 15, and the like are the same as those in the first embodiment.
[0107]
As described above, even when the single crystal silicon having the impurity layer 151A in which boron is diffused is used for the elastic film base material 150A, the same effect as that of the first embodiment described above can be obtained.
[0108]
(Embodiment 3)
FIG. 8 is a cross-sectional view in the longitudinal direction of the pressure generating chamber showing the method of manufacturing the ink jet recording head according to the third embodiment.
[0109]
In this embodiment, the elastic film base material 150B is made of single crystal silicon having a pn junction, and the elastic film 50B is made of n-type single crystal silicon.
[0110]
Here, a method of providing the elastic film 50B in this way will be described in detail. In addition, the overlapping description is abbreviate | omitted about the process similar to the manufacturing method of Embodiment 1 mentioned above.
[0111]
First, as shown in FIG. 8A, the pressure generating chamber 12 is formed in the flow path forming substrate 10 by the same process as that of the first embodiment described above.
[0112]
Next, as shown in FIG. 8B, the elastic film base material 150B is joined to the flow path forming substrate 10 in which the pressure generating chamber 12 is formed.
[0113]
The elastic film base material 150B is not particularly limited as long as it is composed of single crystal silicon having a pn junction, that is, an n-type silicon layer 151B and a p-type silicon layer 152B. The elastic film base material 150B having a pn junction composed of the n-type silicon layer 151B and the p-type silicon layer 152B is formed by doping or the like or epitaxially forming the n-type silicon layer 151B on the surface of the p-type silicon layer 152. can do.
[0114]
And the joining method of the elastic membrane base material 150B formed in this way and the flow path forming substrate 10 is not particularly limited, and for example, both can be joined by direct joining, anodic joining, or the like. In this embodiment, it joined by direct joining similarly to Embodiment 2 mentioned above.
[0115]
Next, as shown in FIG. 8C, an excessive region of the elastic film base material 150B is removed. In the present embodiment, only the region other than the n-type silicon layer 151B, that is, the p-type silicon layer 152B is removed. In the present embodiment, the p-type silicon layer 152B is removed by electrochemical etching with an alkaline aqueous solution such as KOH.
[0116]
Here, in the electrochemical etching, only the p-type silicon layer 152B is etched by changing the magnitude of the voltage applied to the elastic film base material 150B made of single crystal silicon having a pn junction, and only the n-type silicon layer 151B is etched. It is something to leave.
[0117]
Specifically, the n-type silicon layer 151B and the p-type silicon layer 152B have a significantly low silicon etching rate when a voltage higher than a passivation voltage (a little higher than the current reaches a peak value) is applied. Utilizing this property, a voltage lower than the passivation voltage is applied to the p-type silicon layer 152B to be etched, and a voltage higher than the passivation voltage is applied to the n-type silicon layer 151B to be etched. By etching with an alkaline aqueous solution such as, it is possible to etch only the p-type silicon layer 152B and leave the n-type silicon layer 151B.
[0118]
In this embodiment, after forming only the n-type silicon layer 151B on the flow path forming substrate 10 by such electrochemical etching, the elastic film 50B is smoothed by electrolytic polishing on the surface of the n-type silicon layer 151B. Formed.
[0119]
The subsequent steps of forming the piezoelectric element 300, the reservoir 15, and the like are the same as those in the first embodiment.
[0120]
Thus, even when single crystal silicon having a pn junction is used for the elastic film base material 150B, the same effect as that of the first embodiment described above can be obtained.
[0121]
In this embodiment, since the elastic film base material 150B and the flow path forming substrate 10 are directly bonded to each other, a crystal is formed at the bonding interface between the elastic film 50B and the flow path forming substrate 10 as in the second embodiment. It has a lattice mismatch surface, a transition surface, or a void layer.
[0122]
(Embodiment 4)
FIG. 9 is a cross-sectional view in the longitudinal direction of the pressure generating chamber showing the method of manufacturing the ink jet recording head according to the fourth embodiment.
[0123]
This embodiment is an example in which single crystal silicon having a high impurity layer 152C and a low impurity layer 151C made of single crystal silicon having different impurity concentrations is used as the elastic film base material 150C, and the elastic film 50C is made of a low impurity layer 151C. .
[0124]
Here, a method of providing the elastic film 50C in this way will be described in detail. In addition, the overlapping description is abbreviate | omitted about the process similar to the manufacturing method of Embodiment 1 mentioned above.
[0125]
First, as shown in FIG. 9A, the pressure generating chamber 12 is formed in the flow path forming substrate 10 by the same process as that of the first embodiment described above.
[0126]
Next, as illustrated in FIG. 9B, the elastic film base material 150 </ b> C is bonded to the flow path forming substrate 10 in which the pressure generation chamber 12 is formed.
[0127]
In this embodiment, the elastic film base material 150C is made of single crystal silicon having a high impurity layer 152C containing impurities at a high concentration and a low impurity layer 151C containing impurities at a low concentration. The combination of the low impurity layer 151C containing the impurity and the high impurity layer 152C is not particularly limited. For example, N / N ⁺ , N / P ⁺ , P / N ⁺ , P / P ⁺ Any combination of can be used.
[0128]
And the joining method of such elastic film | membrane base material 150C and the flow-path formation board | substrate 10 is not specifically limited, For example, direct joining or normal temperature joining etc. can be mentioned. In the present embodiment, both are joined by direct joining as in the second embodiment described above.
[0129]
Next, as shown in FIG. 9C, an excess region of the elastic film base material 150C is removed.
[0130]
In this embodiment, HF-HNO ₃ A region other than the low impurity layer 151C, that is, only the high impurity layer 152C was removed by electrochemical etching using the system.
[0131]
Where HF-HNO ₃ In the electrochemical etching using the system, first, electrodes are arranged so as to bias the elastic film base material 150C to the positive side with respect to the etching solution. On the other hand, a platinum electrode biased to the negative side is placed in the solution in order to fix the potential of the etching solution. ₂ A mixed solution with O is used. H ₂ O is HNO ₃ Since the oxidizing action is smaller than that of the single crystal silicon, the etching rate of the single crystal silicon is extremely small when no current is passed. However, when a positive voltage is applied to the single crystal silicon, holes are injected from the electrode, so that the OH in the solution ⁻ Ions attach and oxidation of single crystal silicon occurs. Since this oxide easily reacts in the HF solution and dissolves in the etching solution, the dissolution of the single crystal silicon proceeds. At this time, since the resistance is low in the high impurity layer 152C having a high concentration of impurities, a large current flows, and the oxidation of the silicon surface progresses quickly and the etching rate increases. On the other hand, in the low impurity layer 151C having a low concentration of impurities, the etching rate decreases. HF-HNO like this ₃ In the electrochemical etching using the system, the high impurity layer 152C containing a high concentration impurity can be etched to leave only the low impurity layer 151C containing a low concentration impurity.
[0132]
In the present embodiment, such HF-HNO ₃ After forming only the low impurity layer 151C on the flow path forming substrate 10 by electrochemical etching using a system, the surface was smoothed by electrolytic polishing to form the elastic film 50C.
[0133]
The subsequent steps of forming the piezoelectric element 300, the reservoir 15, and the like are the same as those in the first embodiment.
[0134]
As described above, the elastic film 50C may be formed of the low impurity layer 151C using the elastic film base material 150C using the high impurity layer 152C containing a high concentration impurity and the low impurity layer 151C containing a low concentration impurity. The same effects as those of the first embodiment described above can be obtained.
[0135]
In this embodiment, since the elastic film base material 150C and the flow path forming substrate 10 are directly bonded to each other, a crystal lattice is formed at the bonding interface between the elastic film 50C and the flow path forming substrate 10 as in the second embodiment. It has an incommensurate surface, a transition surface, or a void layer.
[0136]
(Embodiment 5)
FIG. 10 is a longitudinal sectional view of the pressure generating chamber showing the manufacturing process of the ink jet recording head according to the fifth embodiment.
[0137]
This embodiment is an example in which the elastic film 50D has a silicon layer 52 made of single crystal silicon on the pressure generating chamber 12 side of the flow path forming substrate 10 and an insulator layer 53 made of silicon oxide on the lower electrode film 60 side. is there.
[0138]
Here, a method of providing the elastic film 50D in this way will be described in detail. In addition, the overlapping description is abbreviate | omitted about the process similar to the manufacturing method of Embodiment 1 mentioned above.
[0139]
First, as shown in FIG. 10A, the pressure generating chamber 12 is formed in the flow path forming substrate 10 by the same process as that of the first embodiment described above. Further, the protective film 55a which is a mask pattern on the flow path forming substrate 10 is removed with hydrofluoric acid or the like so that the single crystal silicon is exposed on the bonding surface of the flow path forming substrate 10.
[0140]
Next, as shown in FIG. 10B, the elastic film base material 150D is joined to the flow path forming substrate 10 in which the pressure generating chamber 12 is formed.
[0141]
In this embodiment, the elastic film base material 150D uses an SOI substrate having silicon layers 52 and 54 made of single crystal silicon on both sides of an insulator layer 53 made of silicon oxide, and one silicon layer 52 flows. It joined so that it might become the path | route formation board | substrate 10 side. In the present embodiment, since the silicon layer 52 and the insulator layer 53 serve as the elastic film 50D, an SOI substrate having a thickness of the silicon layer 52 of approximately 1 μm or less is used.
[0142]
The bonding method between the flow path forming substrate 10 and the elastic film base material 150D is not particularly limited, and examples thereof include room temperature bonding and direct bonding. In this embodiment, both were joined by normal temperature joining.
[0143]
Specifically, surface activation is performed by irradiating the surface of the flow path forming substrate 10 and the elastic film base material 150D with an argon fast atom beam (FAB) to remove the surface layer such as a natural oxide film, and so on. Both are joined by pressing the surfaces in a vacuum.
[0144]
Even when the elastic film base material 150D and the flow path forming substrate 10 are bonded by room temperature bonding, the elastic film base material 150D and the flow path are the same as in the case of the direct bonding in Embodiments 2 to 4 described above. A crystal lattice mismatch plane, a transition plane, or a void layer is formed at the bonding interface with the formation substrate 10.
[0145]
Next, as shown in FIG. 10C, an excessive region of the elastic film base material 150D is removed. In this embodiment, only the region other than the silicon layer 52 and the insulator layer 53, that is, the silicon layer 54 provided on the other surface is removed.
[0146]
In the present embodiment, the silicon layer 54 is removed by wet etching using an alkaline aqueous solution such as KOH. In this wet etching, it is preferable to form a protective film on the surface opposite to the bonding surface of the flow path forming substrate 10 so that the flow path forming substrate 10 made of single crystal silicon is not dissolved by etching. An example of this protective film is parylene (trade name; polyparaxylylene). The protective film made of parylene can be easily formed with a uniform thickness by the CVD method.
[0147]
Then, by removing the silicon layer 54 in this way, an elastic film 50D composed of the silicon layer 52 and the insulator layer 53 is obtained.
[0148]
The subsequent steps of forming the piezoelectric element 300, the reservoir 15, and the like are the same as those in the first embodiment.
[0149]
Thus, even when an SOI substrate is used for the elastic film base material 150D, the same effect as that of the first embodiment described above can be obtained.
[0150]
In the present embodiment, the flow path forming substrate 10 and the elastic film base material 150D are bonded by room temperature bonding. However, the present invention is not limited to this, and for example, the bonding may be performed by anodic bonding as in the first embodiment. It may be. In this anodic bonding, it is necessary to form a silicon oxide layer on each bonding surface of the flow path forming substrate and the elastic film base material. As a result, the elastic film 50D is composed of single crystal silicon and silicon oxide formed on both surfaces thereof. It becomes three layers with layers.
[0151]
(Other embodiments)
While the embodiments of the present invention have been described above, the basic configuration of the ink jet recording head is not limited to that described above.
[0152]
For example, in Embodiments 1 to 5 described above, the pressure generation chamber 12 is provided shallowly without penetrating the flow path forming substrate 10, but the present invention is not limited to this, and pressure generation is performed on a thin flow path forming substrate. Even if the chambers are provided through the chambers, the rigidity of the partition walls defining the pressure generation chambers can be maintained, crosstalk between the pressure generation chambers can be prevented, and ink ejection characteristics can be improved. Even in the case where the pressure generating chamber is provided through the flow path forming substrate as described above, an elastic film having a thickness of about 1 μm or less can be provided by bonding without using an adhesive by being manufactured by the above-described manufacturing method. . Thereby, a manufacturing process can be simplified and manufacturing cost can be reduced.
[0153]
In the first to fifth embodiments described above, the pressure generating chamber 12 is shallowly formed by half etching using a silicon single crystal substrate as the flow path forming substrate 10. However, the present invention is not limited to this. Alternatively, an SOI substrate may be used to form a pressure generating chamber that penetrates the flow path forming layer in the flow path forming layer made of single crystal silicon on one side of the SOI substrate. Thereby, the depth of a pressure generation chamber can be controlled easily and a highly accurate pressure generation chamber can be formed.
[0154]
Furthermore, although Embodiment 1-5 mentioned above illustrated each of anodic bonding, direct bonding, and normal temperature bonding, if a flow-path formation board | substrate and an elastic film can be joined without using an adhesive agent, this invention is limited to this. Is not to be done.
[0155]
In addition, in the formation of the elastic films 50 to 50D of the first to fifth embodiments described above, the etching is performed when removing the extra regions of the elastic film base materials 150 to 150D. If it is removed by mechanical polishing until etching is performed thereafter, the manufacturing time can be shortened and the manufacturing cost can be reduced.
[0156]
Furthermore, in Embodiments 1 to 5 described above, the ink jet recording head having the nozzle openings 21 on the piezoelectric element 300 side of the flow path forming substrate 10 is used. However, the present invention is not limited to this. An ink jet recording head having a nozzle opening on the opposite side may be used. Such an example is shown in FIG. FIG. 11 is a sectional view in the longitudinal direction of the pressure generating chamber.
[0157]
As shown in the figure, the flow path forming substrate 10A is provided with a nozzle communication path 16 and an ink supply path 17 that communicate with both ends of the pressure generating chamber 12 and penetrate to the opposite side of the piezoelectric element 300. Yes. The nozzle communication path 16 and the ink supply path 17 are formed, for example, by wet etching from the side opposite to the piezoelectric element 300.
[0158]
On the other hand, on the surface side where the nozzle communication hole 16 and the ink supply path 17 of the flow path forming substrate 10A are opened, a nozzle opening 21A communicating with the nozzle communication path 16 and an ink supply hole 23 communicating with the ink supply path 17 are provided. The nozzle plate 20A having the same is joined.
[0159]
A reservoir forming substrate 30 and a compliance substrate 40 that define the reservoir 15A are sequentially joined to a region of the nozzle plate 20A facing the ink supply hole 23, and the pressure generating chamber 12 and the reservoir 15A are connected to the nozzle plate 20A. Are communicated with each other through an ink supply hole 23.
[0160]
Furthermore, the ink supplied to the reservoir 15A is supplied from an ink inlet 24 formed in a region facing the reservoir 15A of the nozzle plate 20A.
[0161]
The reservoir forming substrate 30 forms the peripheral wall of the reservoir 15A, and is manufactured by punching a stainless steel plate having an appropriate thickness according to the nozzle numerical aperture and the ink droplet ejection frequency.
[0162]
The ink chamber side plate 40 is made of a stainless steel substrate, and constitutes one wall surface of the reservoir 15A on one surface. Further, a thin wall 41 is formed on the ink chamber side plate 40 by forming a recess 40a on a part of the other surface by half etching. The thin wall 41 is for absorbing the pressure generated when ink droplets are ejected toward the opposite side of the nozzle opening 21A, and is passed to the other pressure generation chamber 12A via the reservoir 15A. Prevent negative pressure from being applied.
[0163]
Even with such an ink jet recording head, the same effects as those of the first to fifth embodiments described above can be obtained.
[0164]
In addition, the ink jet recording heads of these embodiments constitute a part of a recording head unit having an ink flow path communicating with an ink cartridge or the like, and are mounted on the ink jet recording apparatus. FIG. 12 is a schematic view showing an example of the ink jet recording apparatus.
[0165]
As shown in FIG. 12, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.
[0166]
Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S which is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8. It is designed to be transported.
[0167]
【The invention's effect】
As described above, according to the present invention, the bonding layer facing the pressure generation chamber of the diaphragm is formed of single crystal silicon or silicon oxide, and the flow path forming substrate and the bonding layer are bonded without using an adhesive. Therefore, the manufacturing process can be simplified and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing an ink jet recording head according to a first embodiment of the invention.
FIG. 2 is a longitudinal sectional view of a pressure generating chamber of the ink jet recording head according to the first embodiment of the invention.
FIG. 3 is a cross-sectional view showing a manufacturing process of the ink jet recording head according to the first embodiment of the invention.
FIG. 4 is a cross-sectional view showing a manufacturing process of the ink jet recording head according to the first embodiment of the invention.
FIG. 5 is a cross-sectional view showing a manufacturing process of the ink jet recording head according to the first embodiment of the invention.
FIG. 6 is a longitudinal sectional view of a pressure generating chamber showing a modification of the ink jet recording head according to the first embodiment of the invention.
FIG. 7 is a cross-sectional view showing a manufacturing process of an ink jet recording head according to a second embodiment of the invention.
FIG. 8 is a cross-sectional view illustrating a manufacturing process of an ink jet recording head according to a third embodiment of the invention.
FIG. 9 is a cross-sectional view showing a manufacturing process of an ink jet recording head according to a fourth embodiment of the invention.
FIG. 10 is a cross-sectional view showing a manufacturing process of an ink jet recording head according to a fifth embodiment of the invention.
FIG. 11 is a longitudinal sectional view of a pressure generating chamber showing a modification of an ink jet recording head according to another embodiment of the present invention.
FIG. 12 is a schematic view of an ink jet recording apparatus according to an embodiment of the present invention.
[Explanation of symbols]
10, 10A flow path forming substrate
11 Bulkhead
12, 12A Pressure generation chamber
13 Ink communication part
14 Narrow part
15, 15A reservoir
20 Sealing plate
20A nozzle plate
21 Nozzle opening
22 Piezoelectric element holder
23 Ink supply hole
24 Ink inlet
30 Reservoir forming substrate
40 Compliance board
50, 50A, 50B, 50C, 50D Elastic membrane
51 Nozzle communication hole
52 Silicon layer
53 Insulation layer
54 Silicon layer
60 Lower electrode membrane
70 Piezoelectric layer
80 Upper electrode film
90 Lead electrode
150, 150A, 150B, 150C, 150D Elastic membrane base material
151 Silicon oxide layer
151A Impurity layer
151B n-type silicon layer
151C Low impurity layer
152B p-type silicon layer
152C High impurity layer
300 Piezoelectric element

Claims (10)

A flow path forming substrate in which a pressure generating chamber communicating with the nozzle opening is defined, a lower electrode made of a thin film formed by a film forming and lithography method on one surface side of the flow path forming substrate through a vibration plate, and a piezoelectric In a method of manufacturing an ink jet recording head having a piezoelectric element comprising a body layer and an upper electrode,
A step of forming a pressure generating chamber in the flow path forming substrate; a porous silicon layer or a hydrogen ion layer containing hydrogen ions provided on at least one side; and a porous silicon layer or hydrogen ion layer provided on the porous silicon layer or hydrogen ion layer Bonding the bonding layer side of the diaphragm base material having a bonding layer made of single crystal silicon or silicon oxide to the flow path forming substrate without an adhesive, and the porosity of the diaphragm base material Removing the porous silicon layer or the hydrogen ion layer to separate the bonding layer and the region other than the bonding layer to form the diaphragm, and forming the diaphragm on the diaphragm, the lower electrode film, the piezoelectric film, and And a step of forming the piezoelectric element by laminating and patterning an upper electrode film.   2. The flow path forming substrate has a flow path forming layer made of single crystal silicon in which the pressure generating chamber is formed, and the diaphragm base material is bonded to the flow path forming layer. Manufacturing method of inkjet recording head.   The diaphragm base material is an SOI substrate having silicon layers made of single crystal silicon on both sides of an insulator layer, and the bonding layer is made of one of the insulator layer and the silicon layer. 3. A method for producing an ink jet recording head according to 1 or 2.   3. The method of manufacturing an ink jet recording head according to claim 1, wherein the bonding layer is made of single crystal silicon in which boron is diffused.   3. The method of manufacturing an ink jet recording head according to claim 1, wherein the diaphragm base material is made of single crystal silicon having a pn junction, and the bonding layer is n-type single crystal silicon.   3. The method of manufacturing an ink jet recording head according to claim 1, wherein the diaphragm base material is made of two layers of single crystal silicon having different impurity concentrations, and the bonding layer is made of a low concentration layer.   The method of manufacturing an ink jet recording head according to claim 1, wherein in the step of bonding the diaphragm base material to the flow path forming substrate, both are bonded by direct bonding or room temperature bonding. .   3. The method of manufacturing an ink jet recording head according to claim 1, wherein in the step of bonding the diaphragm base material to the flow path forming substrate, both are bonded by anodic bonding.   The step of forming the diaphragm includes removing the region other than the bonding layer of the diaphragm base material after covering the flow path forming substrate with a protective layer. A method for producing an ink jet recording head according to 1.   10. The method of manufacturing an ink jet recording head according to claim 1, wherein in the step of forming the pressure generating chamber, the pressure generating chamber is formed without penetrating the flow path forming substrate. .

Images