JP4298286B2 - Method for manufacturing ink jet recording head - Google Patents

Description

[0001]
The present invention relates to a method for manufacturing an ink jet recording head .
[0002]
[Prior art]
JP-A-5-330066 and JP-A-6-286149 have been proposed as methods for producing an ink jet recording head. In these, a meltable resin to be a flow path mold material is patterned on a substrate on which an ink discharge pressure generating element is formed, and a resin to be an ink flow path wall and an orifice plate is coated thereon to form a discharge port. Later, a manufacturing method in which a meltable resin is eluted is shown, and a highly accurate manufacturing method that does not require a bonding step is proposed. These ink jet recording heads eject ink droplets in a vertical direction with respect to a substrate on which ejection pressure generating elements are formed, and have a structure called “side shooter type” ink jet recording head.
[0003]
[Problems to be solved by the invention]
In general, in a side shooter type ink jet recording head, a rib is used to suppress a phenomenon (crosstalk) in which the pressure or back flow of ink generated when discharging from each discharge port affects the meniscus of the adjacent discharge port. An ink flow path wall is provided and partitioned, and a flow path for each ejection port is formed beyond the common ink flow path (see FIG. 7).
[0004]
However, in such a configuration, as the recording head becomes higher in definition, the interval between the adjacent ejection ports becomes shorter, thereby reducing the width of the ink flow path. When the width of the ink flow path becomes narrower, the flow resistance increases and the time required for the ink to refill the ink flow path after ink ejection (refill time) becomes longer. It is necessary to shorten the distance between the element and the common ink supply port. However, if the orifice plate is made higher in order to increase the ink flow path, the distance between the discharge pressure generating element and the discharge port surface becomes longer, and it becomes difficult to stably discharge small droplets. Further, if the orifice plate is made thinner, its strength is lost and the reliability is lowered.
[0005]
When the distance between the discharge pressure generating element and the common ink supply port is shortened, the distance on the flow path of the adjacent discharge pressure generating element is shortened, and the crosstalk is increased.
[0006]
In order to shorten the ink refill time without using these means, the method is effective if the bottom surface of the ink flow path extending from the common ink supply port to each discharge port is recessed in front of the discharge pressure generating element. is there. However, it has been proposed in Japanese Patent Application Laid-Open No. 5-330066 (Patent Document 1) and Japanese Patent Application Laid-Open No. 6-286149 (Patent Document 2) on a substrate for an ink jet recording head having a depression having a complicated shape on the surface. There is a problem that it is difficult to form an orifice plate and an ink flow path by a technique that does not use such a bonding process.
[0007]
An object of the present invention is to provide a highly reliable ink jet recording head that can sufficiently cope with a high-density arrangement of ejection openings in an ink jet recording head having a structure for ejecting ink in a direction perpendicular to a substrate surface.
[0008]
[Patent Document 1]
JP-A-5-330066 [Patent Document 2]
JP-A-6-286149 [0009]
[Means for Solving the Problems]
In order to solve the above problem, an ink jet recording head substrate and an ink jet recording head manufacturing method in which the bottom surface of the ink flow path can be depressed after forming the orifice plate and the ink flow path on the wafer surface may be used. .
[0010]
That is, the present invention proposes the following.
[0013]
An ink jet recording head manufacturing method according to the present invention corresponds to a substrate, a plurality of ink discharge pressure generating elements for discharging ink disposed on the surface of the substrate, and each of the plurality of ink discharge pressure generating elements. An orifice plate having a plurality of discharge ports, an ink supply port that is provided through the substrate from the back surface of the substrate, and is common to the plurality of discharge ports, a surface of the substrate, and the orifice plate provided independently for each of the discharge ports between, the ink-jet recording head for chromatic ink flow path communicating with the discharge port extending from the ink supply port to the comb-shaped along the substrate surface, the In the manufacturing method,
The surface of the substrate is made of a material that is rapidly etched with respect to the substrate, and is directed to the ink discharge pressure generating element so as to correspond to the band-shaped portion corresponding to the shape of the supply port and the shape of the flow path. Providing a sacrificial layer having a comb-blade-shaped portion extending from the band-shaped portion;
Providing a member to be the orifice plate on the substrate;
Etching the base to reach the sacrificial layer from the back surface, and removing the sacrificial layer from the base by etching;
A method for manufacturing an ink jet recording head, comprising:
[0014]
Made of silicon as the base is preferred. As the etching, etching using an alkaline aqueous solution as an etchant can be used. Further, as the alkaline aqueous solution, an aqueous solution such as potassium hydroxide, tetramethylammonium hydroxide (TMAH), ethylenediamine-pyrocatechol-water (EPW) or hydrazine is preferable. Further, the sacrificial layer can be removed by the etchant .
[0015]
In the present invention, since the sacrificial layer that is easier to etch than the base provided on the base exists, when the base is etched to form an ink supply port that penetrates the base, the sacrificial layer is removed. The portion of the substrate that becomes the bottom surface of the ink flow path is also etched, and a recess is formed at least at the bottom of the connection portion with the ink supply port of the ink flow path. By forming this recess, ink is refilled from the ink supply port common to each ink flow path to each ink flow path, and good performance is ensured even when the ink flow paths are arranged at high density. it can.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The ink jet recording head according to the present invention transfers ink supplied from the back surface of the substrate through an ink supply port provided through the substrate to the substrate from an ejection port provided on the surface (front surface) of the substrate. In contrast, it has a configuration in which ink is ejected in a direction perpendicular to the direction. A typical structure thereof is as shown in FIG. 7, but in the present invention, as shown in FIG. 1, a comb-blade ink flow connected to a part of the ink flow path 104, that is, the ink supply port 106 is used. A part of the bottom including at least the root portion of the path is constituted by a recess formed in the base 101. In the configuration shown in the figure, the discharge pressure applying portion to which the discharge pressure from the ink discharge pressure generating element is applied is positioned corresponding to the discharge port 103 at the bottom of the ink flow path, and the portion excluding this portion is recessed. Is formed.
[0017]
A structure having this recess structure at the bottom of a part of the ink flow path can be obtained by, for example, the following method.
[0018]
First, an ink jet recording head substrate will be described.
[0019]
A plurality of discharge pressure generating elements are arranged at predetermined positions on the surface (front surface) of a flat substrate made of silicon or the like, that is, at positions corresponding to the positions of a plurality of discharge ports formed on the substrate. A wiring for driving the discharge pressure generating element is also formed on the substrate. The substrate is preferably made of silicon. A discharge pressure generating element or the like is disposed on the surface of the substrate.
[0020]
Furthermore, a sacrificial layer made of a material that is easier to etch than the substrate is provided on the substrate surface.
[0021]
The sacrificial layer may be formed before forming the discharge pressure generating element and its drive circuit.
[0022]
The sacrificial layer has a substrate surface direction (a shape in a plan view as viewed from above the substrate surface), a band-shaped portion 209-1 that is a part of the ink supply port, and a portion that extends from the band-shaped portion 209-1 into a comb blade shape. 209-2. A portion 209-2 extending in a comb-blade shape occupies a region forming the bottom of the ink flow path. As shown in FIG. 1, the ink flow path is formed so as to extend to the discharge pressure applying portion in the ink flow path formed at the position where the discharge pressure generating element 202 is disposed. It is formed up to the front of the applying part. By doing so, it is possible to form a recess in the base that is the bottom of the continuous ink flow path including at least the roots of the comb blade shape at the portion other than the discharge pressure applying portion.
[0023]
At this time, it is desirable that the sacrificial layer be etched sufficiently quickly with respect to the substrate. That is, when the sacrificial layer is etched, the corner base at the base of the comb-shaped portion is rapidly etched because it is exposed to the etchant from two directions. This is because if the etching rate of the sacrificial layer is not sufficiently high with respect to the etching rate of the corner portion of the substrate, the depressions cannot be formed in a comb shape along the bottom of the ink flow path. FIG. 8 is an SEM photograph taken after the processing was stopped while the sacrificial layer (aluminum) was being etched and the resin layer such as the positive resist on the substrate surface and the passivation layer were removed. It can be seen that the sacrificial layer is being etched quickly and at the same time the corners of the substrate are being etched.
[0024]
Next, a passivation layer is formed on the surface of the substrate.
[0025]
FIGS. 2A and 2B are a plan view and a cross-sectional view of the substrate, respectively, showing the positional relationship between the sacrificial layer on the surface of the substrate and the discharge pressure generating element at the stage where the passivation layer is formed. As shown in FIG. 1, a heater serving as a discharge pressure generating element and its drive circuit (not shown) are formed on the base. Each of these structures can be obtained by a general-purpose semiconductor process.
[0026]
The sacrificial layer is made of a material that is easier to etch than the substrate, for example, a material having a high etching rate. When a silicon substrate is used as the substrate, polysilicon, aluminum, or the like can be used as the sacrificial layer. Further, a silicon nitride layer can be used as the passivation layer, which can be formed by film formation by a plasma CVD method or the like.
[0027]
The layer thickness of the sacrificial layer is preferably selected from the range of 1000 to 10,000 mm, for example, in consideration of the formation efficiency of the sacrificial layer and the handleability when removing it from the substrate. Further, the passivation layer has a function of insulating each discharge pressure generating element and wiring and protecting each discharge pressure generating element and wiring with respect to the ink in the ink flow path. Considering that the portion on the sacrificial layer is deleted from the substrate, the material, film thickness, and the like can be selected. When the silicon nitride film is used, the film thickness is preferably selected from the range of 1000 to 20000 mm, for example.
[0028]
The inkjet recording substrate according to the present invention may have the configuration shown in FIG. 2, and a mask layer 208 used for opening an ink supply port may be further provided on the back surface of the substrate. Any mask may be used as long as it can act as a resist for etching the substrate. When silicon is used as a base, a silicon oxide film can be suitably used as the mask material.
[0029]
An ink jet recording head using the substrate having the above-described structure can be manufactured as follows.
[0030]
First, as shown in FIG. 3, an opening is formed in a portion corresponding to the ink supply port forming position of the max material layer 208 on the back surface of the base 201. When an oxide film is used, this opening can be formed by patterning the oxide film with buffered hydrofluoric acid using a positive resist as a mask.
[0031]
Next, a flow channel mold material that can be eluted on the surface of the substrate is provided in a shape corresponding to a predetermined comb-blade flow channel, and a discharge port forming material for forming an orifice plate having a discharge port thereon is further provided. Laminate. The orifice plate forming material may be formed by aligning the side walls of the ink flow path.
[0032]
A known material can be used for the flow path mold. For example, this flow path mold material can be obtained by applying a positive resist mainly composed of polymethylisopropenyl ketone, exposing it to Deep-UV light, developing it, and patterning it into a desired mold material shape. . Furthermore, a known material such as a cationic polymerization type epoxy resin can be used as the material for forming the orifice plate. For example, a cationic polymerization type epoxy resin can be applied so as to cover the flow path mold material, and the discharge port can be formed by exposure and development processes.
[0033]
In addition, in order to protect this from a subsequent process, it is good to apply protective agents, such as cyclized rubber, to the base | substrate surface side.
[0034]
The state thus obtained is shown in FIG. In the example shown in FIG. 4, a mold 410 corresponding to a predetermined position on the passivation layer, that is, a region serving as a comb blade-shaped ink flow path extending from the ink supply port, an orifice plate 411, and a protective agent layer 412. Is provided.
[0035]
Next, as shown in FIGS. 5A and 5B, the substrate is etched from the opening of the mask provided on the back surface of the substrate until it reaches the sacrificial layer. When the sacrificial layer is exposed in the etched opening, the sacrificial layer is removed to make the portion occupied by the sacrificial layer hollow. Further, the cavity from which the sacrificial layer has been removed is filled with an etching solution, and the portion of the substrate that has been in contact with the sacrificial layer is etched to form a depression on the surface of the substrate.
[0036]
The depth of the dent is set so that satisfactory refilling can be achieved, and can be adjusted by the material of the substrate, the etching solution, and further the etching conditions. The depth of the recess is preferably in the range of 5 to 50 μm, for example.
[0037]
Further, the portion of the passivation layer on the sacrificial layer and the flow channel mold material are removed to form an ink supply port and an ink flow channel, and the protective agent layer at the discharge port is removed, whereby the ink jet recording having the configuration shown in FIG. You can get a head. A concave portion having a shape indicated by 209-2 in FIG. 2 is formed on the surface of the substrate including at least the root of the comb blade shape of the ink flow path in the head and extending to the front of the arrangement position of the discharge pressure generating element. It forms the bottom of the ink flow path.
[0038]
The etching solution used for etching the substrate can be selected according to the material of the substrate. In the case of a silicon substrate, an alkaline aqueous solution can be suitably used. For example, an aqueous solution of potassium hydroxide or tetramethylammonium hydroxide (TMAH) Can be suitably used.
[0039]
If an etching solution (etchant) for etching the substrate can be used for removing the sacrificial layer, the etching step for opening the ink supply port, the removing step of the sacrificial layer, and the depression of the substrate under the sacrificial layer The etching process for formation can be performed in one process.
[0040]
On the other hand, the passivation layer can be removed by applying chemical dry etching from the back opening side.
[0041]
Further, when a positive resist is used as the flow path mold material, it is possible to irradiate it with UV light from above the orifice plate, and to remove the mold material from the substrate with a developer.
[0042]
Finally, an ink jet recording head can be completed by separating the dicer into chips of each desired unit from the substrate as necessary. A typical configuration thereof is shown in FIG.
[0043]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0044]
A substrate for an ink jet recording head as shown in FIG. 2 was produced by a general-purpose semiconductor process using a silicon wafer having an ingot drawing orientation of <100> and a thickness of 625 μm as the substrate.
[0045]
The ink jet recording head substrate is provided with a heater 202 serving as a discharge pressure generating element and a drive circuit (not shown), aluminum is used for the sacrificial layer 209, and the passivation layer 207 is formed by a plasma CVD method. It is made of filmed silicon nitride.
[0046]
Next, the silicon oxide film 208 on the back surface of the substrate 201 was patterned with buffered hydrofluoric acid using a positive resist (OFPR manufactured by Tokyo Ohka Kogyo Co., Ltd.) as a mask to form an opening for defining the position for forming the ink supply port ( FIG. 3).
[0047]
Next, a positive resist (ODUR manufactured by Tokyo Ohka Kogyo Co., Ltd.) made of polymethylisopropenyl ketone, which is a flow path mold material that can be eluted by the processing described later, is applied to the surface of the substrate, exposed to deep-UV light, and developed. Went and patterned.
[0048]
A cationic polymerization type epoxy resin to be an orifice plate was applied on the flow path mold material, and a discharge port was formed by exposure and development processes. Further, in order to protect the discharge port and the orifice plate 411, cyclized rubber was applied to the substrate surface side and baked (FIG. 4).
[0049]
Thereafter, the substrate was immersed in a tetramethylammonium hydroxide aqueous solution having a temperature of 83 ° C. and a concentration of 21 wt%, and etching was advanced from the oxide film opening on the back surface of the substrate. In about 15 hours, the etching reaches the sacrificial layer on the surface (FIG. 5A), and then the etching proceeds rapidly along the pattern of the sacrificial layer 510, and the substrate 501 under the sacrificial layer 510 is etched to form the depression 513. Was formed (FIG. 5B). Next, chemical dry etching was performed from the back opening side, and the passivating layer on the front side was removed to form a through hole.
[0050]
After thoroughly washing with water and drying, the cyclized rubber on the orifice plate was removed with xylene. Thereafter, the positive resist, which is a flow path mold material, was exposed to UV light from the orifice plate and exposed to light, and ultrasonic waves were applied and eluted while immersed in methyl lactate. Finally, the ink jet recording head was completed by separating each chip state from the wafer by a dicer (FIG. 6).
[0051]
【The invention's effect】
The ink jet recording head manufactured in accordance with the present invention has a recessed bottom portion of the ink flow path extending from a common ink supply port to each heater that is an ejection pressure generating element, and is resistant to crossing compared to a conventional recording head. The ink refill time was short without losing talk performance.
[Brief description of the drawings]
FIG. 1 is a simplified diagram of an ink jet recording head manufactured using an ink jet recording head substrate according to the present invention.
FIG. 2 is a simplified diagram of a substrate for an ink jet recording head according to the present invention.
FIG. 3 is a cross-sectional view of an ink jet recording head manufactured using an ink jet recording head substrate according to the present invention.
FIG. 4 is a cross-sectional view of an ink jet recording head manufactured using an ink jet recording head substrate according to the present invention.
FIG. 5 is a cross-sectional view of an ink jet recording head manufactured using an ink jet recording head substrate according to the present invention in the middle of manufacturing.
FIG. 6 is a cross-sectional view of an ink jet recording head manufactured using the ink jet recording head substrate according to the present invention.
FIG. 7 is a diagram illustrating a conventional example of an ink jet recording head.
FIG. 8 is a photograph taken with an SEM of an ink jet recording head manufactured using an ink jet recording head substrate according to the present invention, in particular during the process of etching a sacrificial layer.
[Explanation of symbols]
101, 201, 701 Silicon substrate 102, 202, 702 Discharge pressure generating element 103, 603, 703 Discharge port 104, 604, 704 Ink flow path 105, 605, 705 Orifice plate 106, 606, 706, 806 Common ink supply port 207 Passivation layer 209 Sacrificial layer 809 Etching sacrificial layer 410 Elutable flow path mold 411 Epoxy resin 412 used as orifice plate Nozzle protection cyclized rubber 513, 813 Indentation 114, 714 at the bottom of the ink flow path Rib (ink channel wall)
815 Cross section when substrate is broken to take SEM picture

Claims (5)

An orifice having a base, a plurality of ink discharge pressure generating elements for discharging ink disposed on the surface of the base, and a plurality of discharge ports provided corresponding to each of the plurality of ink discharge pressure generating elements A plate, an ink supply port that is provided through the substrate from the back surface of the substrate, and is common to the plurality of discharge ports, and independently between each discharge port between the surface of the substrate and the orifice plate in provided, method for manufacturing an ink jet recording head that chromatic ink flow path communicating extends comb shape to the respective discharge ports along the substrate surface from the ink supply port, and
The surface of the substrate is made of a material that is rapidly etched with respect to the substrate, and is directed to the ink discharge pressure generating element so as to correspond to the band-shaped portion corresponding to the shape of the supply port and the shape of the flow path. Providing a sacrificial layer having a comb-blade-shaped portion extending from the band-shaped portion;
Providing a member to be the orifice plate on the substrate;
Etching the base to reach the sacrificial layer from the back surface, and removing the sacrificial layer from the base by etching;
An ink jet recording head manufacturing method comprising: 2. The method of manufacturing an ink jet recording head according to claim 1, wherein the surface of the substrate is made of silicon, and the sacrificial layer is made of polysilicon or aluminum. The step of providing the member to be the orifice plate on the substrate is performed by providing an elution mold material on the sacrificial layer on the substrate, and covering the mold material with the member to be the orifice plate, and the sacrificial material. 3. The method of manufacturing an ink jet recording head according to claim 1, wherein after the layer is removed from the substrate by etching, the mold material is removed from the substrate to form the supply port and the flow path. The method of manufacturing an ink jet recording head according to claim 3, wherein the mold material is a positive resist. The method for manufacturing an ink jet recording head according to claim 3, wherein the discharge port forming material is a cationic polymerization type epoxy resin.

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