KR100528349B1 - Piezo-electric type inkjet printhead and manufacturing method threrof - Google Patents

Abstract

A piezoelectric inkjet printhead and a method of manufacturing the same are disclosed. The piezoelectric inkjet printhead disclosed is made by laminating and bonding three single crystal silicon substrates. The three substrates consist of an upper substrate on which an ink inlet and a plurality of pressure chambers are formed, an intermediate substrate on which a manifold, a plurality of restrictors and a plurality of dampers pass through, and a lower substrate on which a plurality of nozzles are formed. A piezoelectric actuator is integrally formed on the upper substrate forming the diaphragm made of silicon. Then, three substrates are sequentially stacked and bonded to form a common flow path consisting of an ink inlet and a manifold, and an individual flow path consisting of a restrictor, a pressure chamber, a damper, and a nozzle. According to such a configuration, since the manifold, the restrictor, and the damper can be simultaneously formed by a single process through the intermediate substrate, the manufacturing process is simplified, the manufacturing cost is reduced, and the manifold cross-sectional area is increased. The flow resistance of the ink supplied to each pressure chamber is reduced so that the flow rate of the ink supplied from the ink reservoir to each pressure chamber can be ensured appropriately.

Description

Piezoelectric inkjet printhead and its manufacturing method {Piezo-electric type inkjet printhead and manufacturing method threrof}

The present invention relates to an inkjet printhead, and more particularly, to a piezoelectric inkjet printhead implemented on a silicon substrate using a microfabrication technique and a method of manufacturing the same.

In general, an inkjet printhead is a device that prints an image of a predetermined color by ejecting a small droplet of printing ink to a desired position on a recording sheet. The ink ejection method of the inkjet printer includes an electro-thermal transducer (bubble jet method) in which a bubble is generated in the ink by using a heat source to eject the ink with this force, and a piezoelectric material. There is an electro-mechanical transducer (piezoelectric method) in which ink is ejected by a volume change of ink caused by deformation of the piezoelectric body.

The general configuration of the piezoelectric inkjet printhead described above is shown in FIG. Referring to FIG. 1, the manifold 2, the restrictor 3, the pressure chamber 4, and the nozzle 5 constituting the ink flow path are formed inside the flow path forming plate 1. The piezoelectric actuator 6 is provided in the upper part of 1). Manifold (2) is a passage for supplying the ink flowing from the ink reservoir (not shown) to each of the pressure chamber (4), the restrictor (3) is the ink flow into the pressure chamber (4) from the manifold (2) It is a passage. The pressure chamber 4 is a place where the ink to be discharged is filled, and the volume thereof is changed by driving the piezoelectric actuator 6 to generate a pressure change for ejecting or inflowing ink.

The flow path forming plate 1 is mainly formed by cutting a plurality of thin plates of a ceramic material, a metal material or a synthetic resin material to form a portion of the ink flow path as described above, and then stacking the plurality of thin plates. The piezoelectric actuator 6 is provided above the pressure chamber 4, and has a form in which a piezoelectric thin plate and electrodes for applying a voltage to the piezoelectric thin plate are stacked. Accordingly, the portion of the flow path forming plate 1 that forms the upper wall of the pressure chamber 4 serves as the diaphragm 1a that is deformed by the piezoelectric actuator 6.

Referring to the operation of a conventional piezoelectric inkjet printhead having such a configuration, when the diaphragm 1a is deformed by driving the piezoelectric actuator 6, the volume of the pressure chamber 4 is reduced, and thus the pressure chamber. The ink in the pressure chamber 4 is discharged to the outside through the nozzle 5 by the pressure change in 4. Subsequently, when the diaphragm 1a is restored to its original shape by the drive of the piezoelectric actuator 6, the volume of the pressure chamber 4 is increased, and ink is discharged from the manifold 2 by the pressure change. It enters into the pressure chamber 4 via 3.

As a specific example of such a piezoelectric inkjet printhead, FIG. 2 shows a conventional piezoelectric inkjet printhead disclosed in US Pat. No. 5,856,837. 3 is a partial cross-sectional view of a conventional printhead cut in the longitudinal direction of the pressure chamber shown in FIG. 2, and FIG. 4 is a cross-sectional view along the line A-A shown in FIG.

2 to 4 together, a conventional piezoelectric inkjet printhead is formed by stacking and bonding a plurality of thin plates 11 to 16. That is, at the bottom of the printhead, a first plate 11 having a nozzle 11a for discharging ink is disposed, and a second plate having a manifold 12a and an ink discharge port 12b formed thereon ( 12 are stacked, and the third plate 13 having the ink inlet 13a and the ink outlet 13b is stacked thereon. The third plate 13 is provided with an ink inlet 17 for introducing ink from an ink reservoir (not shown) into the manifold 12a. A fourth plate 6 having an ink inlet 14a and an ink outlet 14b is stacked on the third plate 13, and both ends thereof communicate with the ink inlet 14a and the ink outlet 14b, respectively. The fifth plate 15 on which the pressure chamber 15a is formed is stacked. The ink inlets 13a and 14a serve as a passage through which ink flows from the manifold 12a into the pressure chamber 15a, and the ink outlets 12b, 13b and 14b are discharged from the pressure chamber 15a. It serves as a passage through which ink is discharged toward the nozzle 11a. The sixth plate 16 that closes the upper portion of the pressure chamber 15a is stacked on the fifth plate 15, and the drive electrode 20 and the piezoelectric film 21 are formed thereon as a piezoelectric actuator. Therefore, the sixth plate 16 functions as a diaphragm vibrated by the piezoelectric actuator, and the volume of the pressure chamber 15a beneath it is changed by the bending deformation thereof.

The first, second and third plates 11, 12, 13 are generally formed by etching or pressing metal thin plates, and the fourth, fifth and sixth plates 14, 15, 16 are formed. Is generally formed by cutting a ceramic material in the form of a sheet. Meanwhile, the fifth plate 12 on which the manifold 12a is formed may be formed by injection molding or pressing a thin plastic material or an adhesive in the form of a film, or may be formed by pasting the adhesive in the form of a paste. It can be molded by screen printing. And the piezoelectric film 21 formed on the 6th plate 16 is shape | molded by apply | coating and sintering the ceramic material of the paste state which has piezoelectric property.

As described above, in order to manufacture the conventional piezoelectric inkjet printhead shown in FIG. 2, each of a plurality of metal plates and ceramic plates are separately processed by various processing methods, and then stacked and laminated to each other by a predetermined adhesive. Joining process. By the way, in the conventional printhead, the number of plates constituting it is relatively large, and thus there is a disadvantage in that the number of processes for aligning the plates increases, thereby increasing the alignment error. If an alignment error occurs, the flow of ink through the ink flow path is not smooth, which degrades the ink ejection performance of the printhead. In particular, with the recent trend of manufacturing printheads at higher densities for improved resolution, more accuracy is required in the alignment process described above, which leads to an increase in the price of the product.

In addition, since a plurality of plates constituting the printhead are manufactured by different methods with different materials, the complexity of the manufacturing process and the difficulty of bonding between dissimilar materials reduces product yield. In addition, even if a plurality of plates are precisely aligned and bonded in the manufacturing process, there is a problem that alignment error or deformation may occur due to the difference in the coefficient of thermal expansion between different materials in accordance with the change of the ambient temperature during use.

In order to solve this problem, the present applicant is composed of three silicon substrates laminated in a patent application filed on December 18, 2001 and published as a publication No. 2003-0050477, and a piezoelectric actuator is integrated on the upper substrate. A piezoelectric inkjet printhead having a structure has been proposed. A printhead having such a structure has all three substrates made of a single crystal silicon substrate, and thus has excellent adhesion to each other, and has the advantage that conventional problems appearing in the lamination process between dissimilar materials are solved.

By the way, in the above printhead, the damper is formed to penetrate the intermediate substrate, but the manifold and the restrictor are formed at different depths from the upper surface of the intermediate substrate and are not penetrated. Therefore, in order to form dampers, manifolds and restrictors having different depths in the intermediate substrate, it is inconvenient to go through several complicated steps.

The present invention was created to solve the above problems of the prior art, and in particular, by forming a manifold, a restrictor, and a damper by a single process for processing through an intermediate substrate, the manufacturing process is simplified and from the ink reservoir. SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric inkjet printhead and a method of manufacturing the same, which can appropriately secure a flow rate of ink supplied to each pressure chamber.

The present invention to achieve the above technical problem,

An upper substrate on which an ink inlet through which ink is introduced is formed, and on which a plurality of pressure chambers filled with ink to be discharged are formed;

A manifold connected to the ink inlet, a plurality of restrictors connecting the manifold and one end of each of the plurality of pressure chambers, and a plurality of dampers connected to the other ends of each of the plurality of pressure chambers. Board;

A lower substrate having a plurality of nozzles therethrough for discharging ink at a position corresponding to each of the plurality of dampers; And

A piezoelectric actuator integrally formed on the upper substrate to provide a driving force for ejecting ink to each of the plurality of pressure chambers;

The lower substrate, the intermediate substrate, and the upper substrate are all made of a single crystal silicon substrate, and are sequentially stacked and bonded to each other, so that the common flow path formed of the ink inlet and the manifold and the individual of the restrictor, the pressure chamber, the damper, and the nozzle are formed. It provides a piezoelectric inkjet printhead, characterized in that the flow path is formed.

In a preferred embodiment of the present invention, an upper end of each of the manifold and the restrictor is defined by the upper substrate, and each lower end thereof is defined by the lower substrate.

The portion of the upper substrate that forms the upper wall of the pressure chamber serves as a diaphragm that is flexibly deformed by driving the piezoelectric actuator.

Here, the upper substrate is composed of an SOI wafer having a structure in which a first silicon substrate, an intermediate oxide film, and a second silicon substrate are sequentially stacked, and the pressure chamber is formed on the first silicon substrate, and the second It is preferable that a silicon substrate is made to serve as the diaphragm.

The pressure chambers may be arranged in two rows on both sides of the manifold, and in this case, it is preferable that partition walls are formed in the longitudinal direction of the manifold.

It is preferable that a silicon oxide film is formed between the upper substrate and the piezoelectric actuator.

The piezoelectric actuator; And a lower electrode formed on the upper substrate, a piezoelectric film formed on the lower electrode to be positioned above the pressure chamber, and an upper electrode formed on the piezoelectric film to apply a voltage to the piezoelectric film. .

Here, the lower electrode preferably has a two-layer structure in which a Ti layer and a Pt layer are sequentially stacked.

The nozzle may include an ink discharge port formed in a lower portion of the lower substrate, and an ink guide portion formed in an upper portion of the lower substrate to connect the damper and the ink discharge hole.

Here, the ink guide portion preferably has a square pyramid shape whose cross-sectional area gradually decreases from the damper toward the ink discharge port.

In addition, the present invention provides a method of manufacturing a printhead of the above-described structure.

The preparation method of the present invention is:

Preparing an upper substrate, an intermediate substrate, and a lower substrate composed of a single crystal silicon substrate;

An upper substrate processing step of finely processing the prepared upper substrate to form an ink inlet through which ink is introduced and a plurality of pressure chambers filled with ink to be ejected;

By processing the prepared intermediate substrate finely, a manifold which is a common flow path connected to the ink inlet, a plurality of restrictors which are individual flow paths connecting the manifold and one end of each of the plurality of pressure chambers, and the plurality of pressures An intermediate substrate processing step of forming a plurality of dampers connected to the other ends of the chambers through the plurality of dampers;

A lower substrate processing step of finely processing the prepared lower substrate so as to pass through a nozzle connected to the damper;

Stacking and bonding the lower substrate, the intermediate substrate, and the upper substrate sequentially; And

And forming a piezoelectric actuator on the upper substrate to provide a driving force for ejecting ink.

The method may further include forming a base mark on each of the three substrates, which is used as an alignment reference in the bonding step, before the substrate processing step, and before forming the piezoelectric actuator, a silicon oxide film on the upper substrate. Forming a step may be further provided.

In the upper substrate processing step, it is preferable to dry-etch the bottom surface of the upper substrate to a predetermined depth to form the pressure chamber and the ink inlet.

In the upper substrate processing step, an SOI wafer having a structure in which a first silicon substrate, an intermediate oxide film, and a second silicon substrate are sequentially stacked as the upper substrate is used, and the first oxide substrate is an etch stop layer. It is preferable to form the pressure chamber and the ink inlet by dry etching the silicon substrate. In this case, the ink inlet formed at a predetermined depth on the bottom surface of the upper substrate may be penetrated after the pressure chamber forming step or after the piezoelectric actuator forming step.

In the intermediate substrate processing step, it is preferable to simultaneously form the manifold, the plurality of restrictors, and the plurality of dampers by the same processing step of penetrating the intermediate substrate. In this case, the intermediate substrate processing step may be performed by dry etching or sand blasting by inductively coupled plasma (ICP).

The lower substrate processing step; Etching the upper surface of the lower substrate to a predetermined depth to form an ink guide portion connected to the damper, and etching the bottom surface of the lower substrate to form an ink discharge port connected to the ink guide portion. Here, it is preferable to form the ink guide portion having an inclined square pyramid shape by anisotropic wet etching the lower substrate using a (100) plane silicon substrate as the lower substrate.

In the bonding step, the three substrates are preferably stacked by a mask alignment device, and the bonding between the three substrates is preferably performed by a silicon direct bonding (SDB) method. In order to improve bonding between the three substrates, a silicon oxide film is preferably formed on at least a bottom surface of the upper substrate and at least an upper surface of the lower substrate.

The piezoelectric actuator forming step may include; It is preferable to include forming a lower electrode by sequentially stacking a Ti layer and a Pt layer on the upper substrate, forming a piezoelectric film on the lower electrode, and forming an upper electrode on the piezoelectric film, After the forming of the upper electrode, the dicing step of cutting the three substrates in the bonded state by a chip unit, and a polling step of generating a piezoelectric characteristic by applying an electric field to the piezoelectric film of the piezoelectric actuator.

In the piezoelectric film forming step, the piezoelectric film may be formed by applying a piezoelectric material in a paste state onto the lower electrode at a position corresponding to the pressure chamber and then sintering the piezoelectric film, and the application of the piezoelectric material is performed by screen printing. Can be. During the sintering of the piezoelectric material, an oxide film is preferably formed on the inner wall surfaces of the ink flow paths formed on the three substrates.

According to the present invention described above, since the manifold, the restrictor, and the damper can be simultaneously formed by a single process through the intermediate substrate, the manufacturing process is simplified and the manufacturing cost is reduced, and the manifold has a large cross-sectional area. The flow resistance of the ink supplied to each pressure chamber can be reduced so that the flow rate of the ink supplied from the ink reservoir to each pressure chamber can be adequately ensured.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size of each element may be exaggerated for clarity and convenience of description. In addition, when one layer is described as being on top of a substrate or another layer, the layer may be present over and in direct contact with the substrate or another layer, with a third layer in between.

FIG. 5 is an exploded perspective view showing a piezoelectric inkjet printhead partially cut according to a preferred embodiment of the present invention, and FIG. 6 is a cutaway view in a longitudinal direction of the pressure chamber shown in FIG. Fig. 7A and Fig. 7B are cross-sectional views along the BB line and CC line shown in Fig. 6, respectively, in the assembled state of the printhead.

5, 6, 7A and 7B, the piezoelectric inkjet printhead according to the present invention is formed by laminating three substrates 100, 200, and 300 together. Each of the three substrates 100, 200, and 300 is provided with components constituting an ink flow path, and a piezoelectric actuator 190 for generating a driving force for ejecting ink is provided on the upper substrate 100. In particular, all three substrates 100, 200, and 300 are made of a single crystal silicon wafer. Accordingly, by using micromachining techniques such as photolithography and etching, the components forming the ink flow path on each of the three substrates 100, 200, and 300 are finer and more precise. It can be formed easily.

The ink flow path includes an ink inlet 110 through which ink is introduced from an ink reservoir (not shown), a pressure chamber 120 in which ink to be ejected is filled, and a pressure change for ejecting ink, and an ink inlet Manifold 210, which is a common flow path for supplying ink introduced through the 110 to the plurality of pressure chambers 120, and individual flow paths for supplying ink from the manifolds 210 to the respective pressure chambers 120. It consists of an instructor 220 and a nozzle 310 through which ink is discharged from the pressure chamber 120. In addition, between the pressure chamber 120 and the nozzle 310, a damper 230 for concentrating energy generated in the pressure chamber 120 by the piezoelectric actuator 190 toward the nozzle 310 and buffering a sudden pressure change is provided. Can be formed. Components forming the ink flow path are divided into three substrates 100, 200, and 300 as described above.

First, a pressure chamber 120 having a predetermined depth is formed on a bottom surface of the upper substrate 100, and a penetrating ink inlet 110 is formed at one side thereof. The pressure chambers 120 have a longer rectangular parallelepiped shape in the ink flow direction, and are arranged in two rows on both sides of the manifold 210 formed on the intermediate substrate 200. However, the pressure chamber 120 may be arranged in only one row on one side of the manifold 210.

The upper substrate 100 is made of a single crystal silicon wafer widely used in the manufacture of integrated circuits, and particularly preferably made of a silicon-on-insulator (SOI) wafer. The SOI wafer generally has a stacked structure of a first silicon substrate 101, an intermediate oxide film 102 formed on the first silicon substrate 101, and a second silicon substrate 103 bonded onto the intermediate oxide film 102. Have The first silicon substrate 101 is made of silicon single crystal and has a thickness of about several hundred micrometers, and the intermediate oxide film 102 may be formed by oxidizing the surface of the first silicon substrate 101, and the thickness thereof is approximately It is about 1-2 micrometers. The second silicon substrate 103 is also made of silicon single crystal, and its thickness is about several micrometers to several tens of micrometers. The reason why the SOI wafer is used as the upper substrate 100 is that the height of the pressure chamber 120 can be adjusted accurately. That is, since the intermediate oxide layer 102 forming the intermediate layer of the SOI wafer serves as an etch stop layer, when the thickness of the first silicon substrate 101 is determined, the height of the pressure chamber 120 also depends. It is decided. In addition, the second silicon substrate 103 forming the upper wall of the pressure chamber 120 is deformed by the piezoelectric actuator 190 to serve as a diaphragm for changing the volume of the pressure chamber 120, the thickness of the diaphragm. It is determined by the thickness of the second silicon substrate 103. This will be described in detail later.

The piezoelectric actuator 190 is integrally formed on the upper substrate 100. The silicon oxide film 180 is formed between the upper substrate 100 and the piezoelectric actuator 190. The silicon oxide film 180 not only functions as an insulating film but also functions to suppress diffusion and control thermal stress between the upper substrate 100 and the piezoelectric actuator 190. The piezoelectric actuator 190 includes lower electrodes 191 and 192 serving as a common electrode, a piezoelectric film 193 deformed by application of a voltage, and an upper electrode 194 serving as a driving electrode. The lower electrodes 191 and 192 are formed on the entire surface of the silicon oxide film 180, and are preferably made of two metal thin films, a Ti layer 191 and a Pt layer 192. The Ti / Pt layers 191 and 192 not only serve as a common electrode, but also prevent inter-diffusion between the piezoelectric film 193 formed thereon and the upper substrate 100 thereunder. It also serves as a diffusion barrier layer. The piezoelectric film 193 is formed on the lower electrodes 191 and 192 and is disposed to be positioned above the pressure chamber 120. The piezoelectric film 193 is deformed by the application of a voltage, and acts to flexurally deform the second silicon substrate 103 of the upper substrate 100 that forms the upper wall of the pressure chamber 120, that is, the diaphragm. Done. The upper electrode 194 is formed on the piezoelectric film 193 and serves as a driving electrode for applying a voltage to the piezoelectric film 193.

In the intermediate substrate 200, a manifold 210, which is a common flow path connected to the ink inlet 110 and supplies ink introduced through the ink inlet 110 to the plurality of pressure chambers 120, is vertically aligned. It is formed through. In addition, the intermediate substrate 200 is formed with a penetrator 220 which is a separate flow path connecting one end of each of the manifold 210 and the pressure chamber 120 to penetrate in the vertical direction. In addition, a damper 230 for connecting the pressure chamber 120 and the nozzle 310 to the position corresponding to the other end of the pressure chamber 120 is also vertically penetrated in the intermediate substrate 200. As described above, when the pressure chambers 120 are arranged in two rows on both sides of the manifold 210, the partition 215 is formed in the longitudinal direction of the manifold 210 to form the manifold 210. It is preferable to separate the right and left to prevent crosstalk between the ink when the ink flows smoothly and when the piezoelectric actuators 190 on both sides of the manifold 210 are driven. The restrictor 220 not only serves as a passage for supplying ink from the manifold 210 to the pressure chamber 120, but also ink flows back from the pressure chamber 120 toward the manifold 120 when ink is ejected. It also plays a role in suppressing things. In order to suppress such back flow of ink, the restrictor 220 is preferably formed such that its cross-sectional area is smaller than the cross-sectional area of the pressure chamber 120 within a range in which the amount of ink can be properly supplied to the pressure chamber 120. .

The manifold 210, the plurality of restrictors 220, and the plurality of dampers 230 may be formed by processing holes vertically penetrating the intermediate substrate 200 at appropriate positions, as described below. In the bonding step of the substrates 100, 200, and 300, they are connected to each other to form an ink flow path for the flow of ink. Thus, an upper end of each of the manifold 210 and the restrictor 220 is defined by the upper substrate 100, and each lower end thereof is defined by the lower substrate 300.

As described above, when the manifold 210 and the restrictor 220 are formed to penetrate the intermediate substrate 200, the cross-sectional area of the manifold 210 is widened so that the ink supplied to each of the pressure chambers 120 may be formed. Since the flow resistance is reduced, there is an advantage that the flow rate of the ink supplied from the ink reservoir to each pressure chamber 120 can be adequately secured. In addition, in the manufacturing method described later, the process of forming the manifold 210 and the restrictor 220 may be simplified as compared to the conventional method, and thus manufacturing cost may be reduced.

The lower substrate 300 has a nozzle 310 penetrated at a position corresponding to the damper 230. The nozzle 310 is formed at a lower portion of the lower substrate 300 and is formed at an ink discharge port 312 through which ink is discharged, and is formed at an upper portion of the lower substrate 300 to connect the damper 230 and the ink discharge port 312. And an ink guide part 311 which guides ink from the damper 230 toward the ink discharge port 312. The ink discharge port 312 has a shape of a vertical hole having a constant diameter, and the ink guide portion 311 has a square pyramid shape whose cross sectional area gradually decreases from the damper 230 toward the ink discharge port 312. On the other hand, the ink guide portion 311 may be in the shape of a cone or the like even if the shape is not square. However, as will be described later, it is easy to form an ink guide part 311 having a square pyramid shape on the lower substrate 300 made of a single crystal silicon wafer.

The three substrates 100, 200, and 300 thus formed are stacked as described above and bonded to each other to form a piezoelectric inkjet print head according to the present invention. In addition, the ink inlet 110, the manifold 210, the restrictor 220, the pressure chamber 120, the damper 230, and the nozzle 310 are sequentially inside the three substrates 100, 200, and 300. Ink flow paths are formed as connected to each other, and the ink flow paths are formed by portions where the substrates 100, 200, and 300 are not in contact with each other when the three substrates 100, 200, and 300 are bonded to each other.

Referring to the operation of the piezoelectric inkjet printhead according to the present invention having such a configuration is as follows. Ink introduced into the manifold 210 from the ink reservoir (not shown) through the ink inlet 110 is supplied into the pressure chamber 120 through the restrictor 220. In the state where ink is filled in the pressure chamber 120, when a voltage is applied to the piezoelectric film 193 through the upper electrode 194 of the piezoelectric actuator 190, the piezoelectric film 193 is deformed, thereby acting as a diaphragm. The second silicon substrate 103 of the upper substrate 100 is bent downward. Due to the bending deformation of the second silicon substrate 103, the volume of the pressure chamber 120 is reduced, and accordingly, the ink in the pressure chamber 120 passes through the damper 230 by the pressure increase in the pressure chamber 120. It is discharged to the outside through the nozzle 310. At this time, the phenomenon that the ink flows back toward the manifold 210 due to the elevated pressure in the pressure chamber 120 is suppressed by the restrictor 220. Then, the ink reaching the nozzle 230 through the damper 230 is discharged to the outside through the ink discharge port 312 through the ink guide portion 311.

Subsequently, when the voltage applied to the piezoelectric film 193 of the piezoelectric actuator 190 is cut off, the piezoelectric film 193 is restored to its original state, whereby the second silicon substrate 103 serving as the diaphragm is restored to its original state and thus the pressure chamber. The volume of 120 is restored to the state before voltage application. As a result, the ink flows from the manifold 210 into the pressure chamber 120 through the restrictor 220 due to the decrease in pressure in the pressure chamber 120 and the surface tension caused by the meniscus of the ink formed in the nozzle 310. do.

Hereinafter, a method of manufacturing a piezoelectric inkjet printhead according to the present invention will be described with reference to the accompanying drawings.

First, a general description of the preferred manufacturing method of the present invention, first manufacturing the upper substrate, the intermediate substrate and the lower substrate on which the components constituting the ink flow path, respectively, and then laminated and bonded three prepared substrates, and finally By forming a piezoelectric actuator on the upper substrate, the piezoelectric inkjet printhead according to the present invention is completed. Meanwhile, the steps of manufacturing the upper substrate, the intermediate substrate, and the lower substrate may be performed in any order. That is, the lower substrate or the intermediate substrate may be manufactured first, or two or three substrates may be manufactured at the same time. However, for convenience of description, the respective manufacturing methods will be described in the order of the upper substrate, the intermediate substrate, and the lower substrate.

8A to 8E are cross-sectional views for explaining a step of forming a base mark on an upper substrate in a method of manufacturing a piezoelectric inkjet printhead according to the present invention.

First, referring to FIG. 8A, in the present embodiment, the upper substrate 100 is made of a single crystal silicon substrate. This is because silicon wafers widely used in the manufacture of semiconductor devices can be used as they are and are effective for mass production. The thickness of the upper substrate 100 is approximately 100 to 200 µm, preferably approximately 150 µm, which may be appropriately determined according to the height of the pressure chamber (120 of FIG. 5) formed on the bottom surface of the upper substrate 100. Can be. It is preferable to use an SOI wafer as the upper substrate 100 because the height of the pressure chamber (120 in FIG. 5) can be accurately formed. As described above, the SOI wafer is formed of the first silicon substrate 101, the intermediate oxide film 102 formed on the first silicon substrate 101, and the second silicon substrate 103 bonded onto the intermediate oxide film 102. It has a laminated structure. In particular, the second silicon substrate 103 has a thickness of several μm to several tens of μm to form the thickness of the diaphragm so that ink ejection may be easily implemented.

When the upper substrate 100 is placed in an oxidation furnace and wet or dry oxidation, the upper and lower surfaces of the upper substrate 100 are oxidized to form silicon oxide films 151a and 151b.

Next, as shown in FIG. 8B, photoresist PR is applied to the surfaces of the silicon oxide films 151a and 151b formed on the upper and lower surfaces of the upper substrate 100, respectively. Subsequently, the coated photoresist PR is developed to form an opening 141 for forming a base mark near the edge of the upper substrate 100.

Next, as illustrated in FIG. 8C, the upper substrate 100 may be wet-etched and removed using the photoresist PR as an etch mask to remove the silicon oxide layers 151a and 151b exposed through the opening 141. After partially exposing the photoresist (PR) is stripped.

Next, as shown in FIG. 8D, the base mark 140 is formed by wet etching the upper substrate 100 of the exposed portion using the silicon oxide films 151a and 151b as an etching mask to a predetermined depth. In this case, in wet etching of the upper substrate 100, for example, TMAH (Tetramethyl Ammonium Hydroxide; tetramethyl ammonium hydroxide) or KOH (potassium hydroxide) may be used as an etchant for silicon.

After the base mark 140 is formed, the remaining silicon oxide films 151a and 151b may be removed by wet etching. This is to clean the foreign materials such as by-products generated in the process of the above steps with the removal of the silicon oxide film (151a, 151b).

As a result, as shown in FIG. 8E, the upper substrate 100 having the base mark 140 formed near the top and bottom edges is prepared.

The base mark 140 formed through the above steps is used as a reference for accurately aligning the upper substrate 100 and the intermediate substrate and the lower substrate which will be described later. Therefore, in the case of the upper substrate 100, the base mark 140 may be formed only on the bottom surface. In addition, when the other alignment method or apparatus is used, the base mark 140 may not be necessary, and in this case, the above steps are not performed.

9A to 9G are cross-sectional views illustrating a process of forming a pressure chamber on an upper substrate.

First, as shown in FIG. 9A, the upper substrate 100 prepared through the above-described steps is put in an oxidation furnace and wet or dry oxidized to form silicon oxide films 152a and 152b on the upper and lower surfaces of the upper substrate 100. Form. In this case, the silicon oxide film 152b may be formed only on the bottom surface of the upper substrate 100.

Next, as shown in FIG. 9B, photoresist PR is applied to the surface of the silicon oxide film 152b formed on the bottom surface of the upper substrate 100. Subsequently, the coated photoresist PR is developed to form an opening 121 for forming a pressure chamber having a predetermined depth on the bottom surface of the upper substrate 100.

Next, as illustrated in FIG. 9C, the silicon oxide film 152b of the portion exposed through the opening 121 may be formed using a photoresist PR as an etching mask, such as reactive ion etching (RIE). The bottom surface of the upper substrate 100 is partially exposed by removing by dry etching. In this case, the silicon oxide layer 152b may be removed by wet etching instead of dry etching.

Next, as shown in FIG. 9D, the pressure chamber 120 is formed by etching the upper substrate 100 of the exposed portion by using the photoresist PR as an etching mask for a predetermined depth. In this case, etching of the upper substrate 100 may be performed by a dry etching method using an inductively coupled plasma (ICP).

In addition, when the SOI wafer is used as the upper substrate 100 as shown, since the intermediate oxide layer 102 of the SOI wafer serves as an etch stop layer, the first silicon substrate 101 may be used in this step. ) Is only etched. Therefore, when the thickness of the first silicon substrate 101 is adjusted in the wafer polishing process, the pressure chamber 120 can be accurately adjusted to a desired height. Meanwhile, the second silicon substrate 103 constituting the upper wall of the pressure chamber 120 serves as a diaphragm as described above, and the thickness thereof may be easily adjusted in the wafer polishing process.

After the pressure chamber 120 is formed, the photoresist PR is stripped to prepare the upper substrate 100 in a state as shown in FIG. 9E. However, in such a state, foreign substances such as by-products or polymers generated during the dry etching process by the above-described wet etching, reactive ion etching (RIE), or inductively coupled plasma (ICP) are contained in the upper substrate ( 100) may be attached to the surface. Therefore, it is preferable to clean the entire surface of the upper substrate 100 by using sulfuric acid solution or tetramethyl ammonium hydroxide (TMAH) to remove these foreign substances. At this time, the remaining silicon oxide films 152a and 152b are also removed by wet etching, and a portion of the intermediate oxide film 102 of the upper substrate 100, that is, a part of the upper wall surface of the pressure chamber 120 is removed.

As a result, as shown in FIG. 9F, the base substrate 140 is formed near the top and bottom edges, and the upper substrate 100 having the pressure chamber 120 formed thereon is prepared.

In the above, the upper substrate 100 is dry etched using the photoresist PR as an etching mask to form the pressure chamber 120, and then the photoresist PR is stripped. Alternatively, the pressure chamber 120 may be formed by first etching the upper substrate 100 by stripping the photoresist PR and then using the silicon oxide layer 152b as an etching mask. That is, when the silicon oxide film 152b formed on the bottom surface of the upper substrate 100 is relatively thin, it is preferable to perform etching to form the pressure chamber 120 with the photoresist PR as it is, and the silicon oxide film 152b. ) Is relatively thick, it is preferable to perform etching using the silicon oxide film 152b as an etching mask after stripping the photoresist PR.

As illustrated in FIG. 9G, the silicon oxide films 153a and 153b may be formed on the upper and lower surfaces of the upper substrate 100 in the state illustrated in FIG. 9F. At this time, the intermediate oxide film 102 that has been partially removed in the step shown in FIG. 9F is supplemented by the silicon oxide film 153b. As such, when the silicon oxide films 153a and 153b are formed, the step of forming the silicon oxide film 180 as the insulating film on the upper substrate 100 may be omitted in the step of FIG. 15A described later. In addition, when the silicon oxide film 153b is formed on the inner surface of the pressure chamber 120 forming the ink flow path, various kinds of inks may be used since the silicon oxide film 153b has little reactivity with the ink.

On the other hand, although not shown, an ink inlet (110 in FIG. 10A) is also formed together with the pressure chamber 120 through the steps shown in FIGS. 9A-9G. That is, when the step shown in FIG. 9E is reached, an ink inlet 110 having such a depth is formed on the bottom surface of the upper substrate 100 along with the pressure chamber 120 having a predetermined depth. As such, the ink inlet 110 formed at a predetermined depth on the bottom surface of the upper substrate 100 has an ink reservoir (not shown) through post-processing through the upper substrate 100 after the bonding process of the substrates and the installation process of the piezoelectric actuator are completed. Can be connected to That is, the penetration of the ink inlet 100 may be performed after the forming step of the piezoelectric actuator is completed. Meanwhile, the post-processing through the upper substrate 100 may be formed by processing the second silicon substrate 103 remaining on the ink inlet 100 in the step illustrated in FIG. 9F.

In addition, after the process illustrated in FIG. 9E of the upper substrate 100 as described above, the ink inlet 100 may be opened by performing a dry etching process of the additional second silicon substrate 103. This method will be described in more detail with reference to the drawings below.

10A through 10E are cross-sectional views illustrating a step of forming an ink inlet on an upper substrate, and are cross-sectional views taken along the line D-D shown in FIG. 5.

Referring to FIG. 10A, the ink inlet 110 may be formed together with the pressure chamber 120 through the steps illustrated in FIGS. 9A through 9E. Specifically, FIG. 10A illustrates a state in which the pressure chamber 120 and a portion of the ink inlet 110 are formed after the step of FIG. 9E is performed among the steps of forming the pressure chamber 120.

Next, as shown in FIG. 10B, photoresist PR is applied to the surface of the silicon oxide film 152a formed on the upper surface of the upper substrate 100. Subsequently, the coated photoresist PR is developed to form an opening 111 for penetrating the ink inlet 110 on the upper surface of the upper substrate 100.

Next, as illustrated in FIG. 10C, the silicon oxide film 152a of the portion exposed through the opening 111 may be formed using a photoresist PR as an etching mask, such as reactive ion etching (RIE). The top surface of the upper substrate 100 is partially exposed by removing by dry etching. In this case, the silicon oxide layer 152a may be removed by wet etching instead of dry etching.

Next, as illustrated in FIG. 10D, the exposed upper substrate 100 is etched to a predetermined depth using the photoresist PR as an etching mask, and then the photoresist PR is stripped. In this case, etching of the upper substrate 100 may be performed by a dry etching method using an inductively coupled plasma (ICP). As described above, after the photoresist PR is first stripped, the upper substrate 100 may be etched using the silicon oxide film 152a as an etching mask. In this step, since the intermediate oxide film 102 of the SOI wafer used as the upper substrate 100 serves as an etch stop layer, only the second silicon substrate 103 is etched and the ink inlet 110 ), The intermediate oxide film 102 remains.

Next, as shown in FIG. 10E, an upper substrate (using a red acid solution or tetramethyl ammonium hydroxide (TMAH)) is used to remove the silicon oxide films 152a and 152b remaining on the upper substrate 100. 100) Clean the entire surface. At this time, the intermediate oxide film 102 remaining on the ink inlet 110 is removed together to penetrate the ink inlet 110.

Thereafter, as described above, the upper substrate 100 having the ink inlet 110 penetrated through the steps of FIG. 9G may be completed.

11A-11F are cross-sectional views showing step by step a first method of forming a manifold, a restrictor and a damper on an intermediate substrate.

Referring to FIG. 11A, the intermediate substrate 200 is made of a single crystal silicon substrate, and its thickness is about 200 to 300 μm.

First, the base mark 240 is formed near the top and bottom edges of the intermediate substrate 200. Since the steps of forming the base mark 240 on the intermediate substrate 200 are the same as those shown in FIGS. 8A to 8E, a separate illustration and description thereof will be omitted for the intermediate substrate 200.

When the intermediate substrate 200 having the base mark 240 formed thereon is placed in an oxidation furnace and wet or dry oxidized, the top and bottom surfaces of the intermediate substrate 200 are oxidized, as shown in FIG. , 251b) is formed.

Next, as shown in FIG. 11B, photoresist PR is applied to the surface of the silicon oxide film 251a formed on the upper surface of the intermediate substrate 200. Subsequently, the coated photoresist PR is developed in a pattern as shown in FIG. 7B to form a manifold and a plurality of restrictors on the upper surface of the intermediate substrate 200, and a plurality of dampers. A second opening 231 for forming a portion is formed. At this time, when the partition is formed inside the manifold, the photoresist PR is left in the portion where the partition is to be formed.

Next, as shown in FIG. 11C, the silicon oxide layer 251a of the portions exposed through the first and second openings 211 and 231 are wet-etched and removed using the photoresist PR as an etching mask. The upper surface of the intermediate substrate 200 is partially exposed. In this case, the silicon oxide layer 251a may be removed by dry etching such as reactive ion etching (RIE) instead of wet etching.

Subsequently, when the photoresist PR is stripped, as shown in FIG. 11D, only the portions of the upper surface where the manifold, the plurality of restrictors, and the plurality of dampers are to be formed are exposed and the remaining portions of the silicon oxide films 251a and 251b. The intermediate substrate 200 in a state covered by is formed.

Subsequently, as shown in FIG. 11E, when the intermediate substrate 200 of the exposed portion is dry etched using the silicon oxide film 251a as an etch mask, the manifold 210 and the restrictor penetrating the intermediate substrate 200 are dry. The 220 and the damper 230 are formed, and the partition 215 is formed inside the manifold 210 to separate them from side to side. In this case, the intermediate substrate 200 may be etched by a dry etching method using an inductively coupled plasma (ICP).

Next, the remaining silicon oxide films 251a and 251b may be removed by wet etching. This is for cleaning foreign matters such as by-products generated in the process of the above steps with the removal of the silicon oxide films 251a and 251b. On the other hand, the foreign matter may be washed with a solution such as sulfuric acid.

As a result, as shown in FIG. 11F, the base mark 240 is formed, and the manifold 210, the restrictor 220, and the damper 230 penetrate the intermediate substrate 200. The intermediate substrate 200 is prepared.

Although not shown, the silicon oxide film may be formed on the entire upper and lower surfaces of the intermediate substrate 200 in the state illustrated in FIG. 11F.

As described above, according to the manufacturing method of the present invention, since the manifold 210, the restrictor 220, and the damper 230 may be simultaneously formed by a single process of etching through the intermediate substrate 200. Compared with the conventional manufacturing method, the process is simple and the manufacturing cost is reduced.

12A and 12B are cross-sectional views showing step by step a second method of forming a manifold, a restrictor and a damper on an intermediate substrate. The second method described below is the same as the first method described above except for the method of etching through the intermediate substrate 200. Therefore, only parts different from the above-described first method will be described below.

In the second method, forming the silicon oxide films 251a and 251b on the surface of the intermediate substrate 200 is the same as that of FIG. 11A of the first method.

Next, as shown in FIG. 12A, photoresist PR is formed on the surface of the silicon oxide film 251a formed on the upper surface of the intermediate substrate 200. In this case, the photoresist PR in the form of a dry film is formed by a lamination method of heating and pressing the silicon oxide film 251a to be pressed. The photoresist PR in the form of a dry film functions as a protective film for protecting other portions of the intermediate substrate 200 during sandblasting described later. Subsequently, the photoresist PR is developed in a pattern as shown in FIG. 7B to form a first opening 211 and a plurality of dampers for forming a manifold and a plurality of restrictors on the upper surface of the intermediate substrate 200. A second opening 231 is formed for the purpose. At this time, when the partition is formed inside the manifold, the photoresist PR is left in the portion where the partition is to be formed.

Next, when the silicon oxide film 251a and the intermediate substrate 200 under the portions exposed through the first and second openings 231 are removed by sand blasting, shown in FIG. 12B. As illustrated, a manifold 210, a restrictor 220, and a damper 230 penetrating the intermediate substrate 200 are formed, and a partition wall 215 is formed inside the manifold 210 to separate them from side to side. Is formed.

Next, after stripping the remaining photoresist (PR), the remaining silicon oxide film (251a, 251b) is removed by wet etching, the intermediate substrate 200 as shown in Figure 11f of the first method The intermediate substrate 200 having the manifold 210, the restrictor 220, and the damper 230 formed therethrough is prepared.

As described above, the second method is different from the first method in that the manifold 210, the restrictor 220, and the damper 230 are formed by sand blasting rather than dry etching. That is, in order to form the manifold 210, the restrictor 220, and the damper 230 in the intermediate substrate 200, the silicon oxide film 251a is etched in the first method and then penetrated through the intermediate substrate 200. Although dry etching, in the second method, the silicon oxide films 251a and 251b and the intermediate substrate 200 are removed at a time by sand blasting. Therefore, the second method has an advantage in that process steps are reduced and process time can be shortened as compared with the first method.

13A to 13I are cross-sectional views for describing a step of forming a nozzle on a lower substrate.

Referring to FIG. 13A, the lower substrate 300 is made of a single crystal silicon substrate, and its thickness is about 100 to 200 μm.

First, the base mark 340 is formed near the top and bottom edges of the lower substrate 300. Since forming the base mark 340 on the lower substrate 300 is the same as the steps shown in Figures 8a to 8e, a separate illustration and description for the lower substrate 300 will be omitted.

When the lower substrate 300 having the base mark 340 formed thereon is placed in an oxidation furnace and wet or dry oxidized, as shown in FIG. 13A, the upper and lower surfaces of the lower substrate 300 are oxidized to form a silicon oxide film 351a. , 351b) is formed.

Next, as shown in FIG. 13B, photoresist PR is applied to the surface of the silicon oxide film 351a formed on the upper surface of the lower substrate 300. Subsequently, the coated photoresist PR is developed to form an opening 315 for forming an ink guide part of the nozzle on the upper surface of the lower substrate 300. The opening 315 is formed at a position corresponding to the damper 230 formed in the intermediate substrate 200 illustrated in FIG. 11F.

Next, as shown in FIG. 13C, the upper surface of the lower substrate 300 is removed by wet etching by removing the silicon oxide film 351a of the portion exposed through the opening 315 using the photoresist PR as an etching mask. After partially exposing the photoresist (PR) is stripped. In this case, the silicon oxide layer 351a may be removed by dry etching such as reactive ion etching (RIE) instead of wet etching.

Next, as shown in FIG. 13D, the ink guide part 311 is formed by wet etching the lower substrate 300 of the exposed portion using the silicon oxide film 351a as an etching mask to a predetermined depth. In this case, in the wet etching of the lower substrate 300, TMAH (Tetramethyl Ammonium Hydroxide) or KOH (Potassium hydroxide) is used as an etchant. In addition, when the (100) plane silicon substrate is used as the lower substrate 300, an ink guide part 311 having a square pyramid shape may be formed using the anisotropic wet etching characteristics of the (100) plane and the (111) plane. That is, since the etching speed of the (111) plane is considerably slower than the etching speed of the (100) plane, the lower substrate 300 is obliquely etched along the (111) plane to form an ink guide part 311 having a square pyramid shape. Done. And the bottom surface of the ink guide part 311 becomes a (100) surface.

Next, as shown in FIG. 13E, photoresist PR is applied to the surface of the silicon oxide film 351b formed on the bottom surface of the lower substrate 300. Subsequently, the coated photoresist PR is developed to form an opening 316 for forming an ink discharge port of the nozzle on the bottom surface of the lower substrate 300.

Next, as shown in FIG. 13F, the bottom surface of the lower substrate 300 is removed by wet etching by removing the silicon oxide film 351b of the portion exposed through the opening 316 using the photoresist PR as an etching mask. Partially expose In this case, the silicon oxide layer 351b may be removed by dry etching such as reactive ion etching (RIE), not wet etching.

Next, as shown in FIG. 13G, the lower substrate 300 of the exposed portion is etched to penetrate using the photoresist PR as an etch mask, thereby forming an ink discharge port 312 connected to the ink guide part 311. Form. In this case, etching of the lower substrate 300 may be performed by a dry etching method using an inductively coupled plasma (ICP).

Subsequently, when the photoresist PR is stripped, as shown in FIG. 13H, a base mark 340 is formed near the top and bottom edges, and a nozzle 310 including an ink inlet 311 and an ink outlet 312. The lower substrate 300 is formed in a state where the penetrating is formed.

Meanwhile, the silicon oxide films 351a and 351b formed on the upper and lower surfaces of the lower substrate 300 may be removed for cleaning, and as shown in FIG. 13I, new surfaces of the lower substrate 300 may be removed. Silicon oxide films 352a and 352b may be formed again. At this time, the silicon oxide films 352a and 352b to be formed are also formed on the inner surface of the nozzle 310.

14 is a cross-sectional view illustrating a step of sequentially stacking and bonding a lower substrate, an intermediate substrate, and an upper substrate.

Referring to FIG. 14, the lower substrate 300, the intermediate substrate 200, and the upper substrate 100 prepared through the above-described steps are sequentially stacked and bonded to each other. In this case, after the intermediate substrate 200 is bonded to the lower substrate 300, the upper substrate 300 is bonded to the intermediate substrate 200 again, but the order may be changed. The three substrates 100, 200, and 300 are aligned using a mask aligner, and further, alignment base marks 140, 240 340 are formed on each of the three substrates 100, 200, and 300. As a result, the alignment accuracy is high. In addition, the bonding between the three substrates 100, 200, and 300 may be performed by a well-known silicon direct bonding (SDB) method. On the other hand, in the SDB (Silicon Direct Bonding) process, bonding between silicon and a silicon oxide film is superior to bonding between silicon and silicon. Therefore, preferably, as shown in FIG. 14, the upper substrate 100 and the lower substrate 300 are used with the silicon oxide films 153a, 153b, 352a, and 352b formed on the surfaces thereof, respectively, The substrate 200 is used in a state where no silicon oxide film is formed on the surface thereof.

When the three substrates 100, 200, and 300 are laminated and bonded as described above, the ink flow paths for the ink flow in the inkjet head are all connected. That is, the flow path is formed so that ink may be supplied from the ink reservoir (not shown) through the ink introduction port 110 to be supplied to the plurality of pressure chambers 120 through the manifold 210 which is a common flow path. In addition, by the bonding process, the restrictor 220, the pressure chamber 120, the damper 230, and the nozzle 310 connected to the manifold 210 are all connected to enable ink flow. Therefore, the ink flow path is formed by a portion where the substrates 100, 200, 300 do not contact each other when the three substrates 100, 200, 300 are bonded to each other, and the manifold 210 and the restrictor are formed. The upper and lower ends of each of the 220 are defined by the upper substrate 100 and the lower substrate 300.

15A and 15B are cross-sectional views illustrating a step of forming a piezoelectric actuator on an upper substrate to complete a piezoelectric inkjet printhead according to the present invention.

First, referring to FIG. 15A, in a state in which the lower substrate 100, the intermediate substrate 200, and the upper substrate 300 are sequentially stacked and bonded to each other, the silicon oxide film 180 is formed as an insulating film on the upper surface of the upper substrate 100. Form. However, the step of forming the silicon oxide film 180 can be omitted. That is, when the silicon oxide film 153a is already formed on the upper surface of the upper substrate 100 as shown in FIG. 14, or annealing in the above-described silicon direct bonding (SDB) process. In the case where an oxide film having a sufficient thickness has already been formed on the upper surface of the upper substrate 100, it is not necessary to form the silicon oxide film 180 shown in Fig. 15A again as an insulating film thereon.

Subsequently, lower electrodes 191 and 192 of the piezoelectric actuator are formed on the silicon oxide film 180. The lower electrodes 191 and 192 are formed of two metal thin layers, a Ti layer 191 and a Pt layer 192. The Ti layer 191 and the Pt layer 192 may be formed by sputtering a predetermined thickness on the entire surface of the silicon oxide film 180. The Ti / Pt layers 191 and 192 not only serve as a common electrode of the piezoelectric actuator, but also interdiffusion between the piezoelectric film (193 of FIG. 15B) formed thereon and the upper substrate 100 beneath it. It also serves as a diffusion barrier to prevent inter-diffusion. In particular, the Ti layer 191 below also serves to increase the adhesion of the Pt 192 layer.

Next, as shown in FIG. 15B, the piezoelectric film 193 and the upper electrode 194 are formed on the lower electrodes 191 and 192. Specifically, the piezoelectric material in a paste state is coated on the upper portion of the pressure chamber 120 by screen printing, and then dried for a predetermined time. Various piezoelectric materials may be used, but a conventional lead zirconate titanate (PZT) ceramic material is preferably used. Subsequently, an electrode material such as Ag-Pd paste is printed on the dried piezoelectric film 193. Next, the piezoelectric film 193 is sintered at a predetermined temperature, for example, 900 to 1,000 占 폚. In this case, inter-diffusion between the piezoelectric film 193 and the upper substrate 100, which may occur during the high temperature sintering of the piezoelectric film 193, is prevented by the Ti / Pt layers 191 and 192. do.

As a result, the piezoelectric actuator 190 including the lower electrodes 191 and 192, the piezoelectric film 193, and the upper electrode 194 is formed on the upper substrate 100.

On the other hand, since the sintering of the piezoelectric film 193 is performed in the atmosphere, a silicon oxide film is formed on the inner surface of the ink flow paths formed on the three substrates 100, 200, and 300 in this step. Since the silicon oxide film formed as described above is not reactive with almost all kinds of inks, various inks may be used. In addition, since the silicon oxide film has hydrophilicity, air bubbles are prevented from entering during the initial inflow of the ink, and generation of bubbles is suppressed even during the ejection of the ink.

Finally, a dicing process of cutting the three substrates 100, 200, and 300 in the bonded state in units of chips, and a polling process of generating piezoelectric properties by applying an electric field to the piezoelectric film 193. After passing through, the piezoelectric inkjet printhead according to the present invention is completed. Meanwhile, dicing may be performed before the sintering step of the piezoelectric film 193 described above.

While the preferred embodiments of the present invention have been described in detail, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. For example, the method of forming each component of the printhead in the present invention is merely exemplary, and various etching methods may be applied, and the order of each step of the manufacturing method may be different from that illustrated. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

As described above, the piezoelectric inkjet printhead and its manufacturing method according to the present invention have the following effects.

First, since the manifold and the restrictor are formed through the intermediate substrate, the cross-sectional area of the manifold is widened to decrease the flow resistance of the ink supplied to each pressure chamber, so that the flow rate of the ink supplied from the ink reservoir to each pressure chamber is increased. It can be secured appropriately.

Second, since the manifold, the restrictor, and the damper can be simultaneously formed by a single process through the intermediate substrate, the manufacturing process is simplified and the manufacturing cost is reduced.

1 is a cross-sectional view for explaining a general configuration of a conventional piezoelectric inkjet printhead.

2 is an exploded perspective view showing a specific example of a conventional piezoelectric inkjet printhead.

3 is a partial cross-sectional view of a conventional printhead cut in the longitudinal direction of the pressure chamber shown in FIG. 2, and FIG. 4 is a cross-sectional view along the line A-A shown in FIG.

5 is an exploded perspective view of a piezoelectric inkjet printhead partially cut according to an exemplary embodiment of the present invention.

FIG. 6 is a partial cross-sectional view of an assembled state of a printhead according to a preferred embodiment of the present invention, cut in the longitudinal direction of the pressure chamber shown in FIG. 5, and FIGS. 7A and 7B respectively illustrate the BB line and the CC line shown in FIG. According to the cross-sectional view.

8A to 8E are cross-sectional views for explaining a step of forming a base mark on an upper substrate in a method of manufacturing a piezoelectric inkjet printhead according to the present invention.

9A to 9G are cross-sectional views illustrating a process of forming a pressure chamber on an upper substrate.

10A to 10E are cross-sectional views for explaining a step of forming an ink inlet on an upper substrate.

11A-11F are cross-sectional views showing step by step a first method of forming a manifold, a restrictor and a damper on an intermediate substrate.

12A and 12B are cross-sectional views showing step by step a second method of forming a manifold, a restrictor and a damper on an intermediate substrate.

13A to 13I are cross-sectional views for describing a step of forming a nozzle on a lower substrate.

14 is a cross-sectional view illustrating a step of sequentially stacking and bonding a lower substrate, an intermediate substrate, and an upper substrate.

15A and 15B are cross-sectional views illustrating a step of forming a piezoelectric actuator on an upper substrate to complete a piezoelectric inkjet printhead according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100 ... top substrate 101 ... first silicon substrate

102 Intermediate Oxide 103 Second Silicon Substrate

110 Ink inlet 120 Pressure chamber

180 ... silicon oxide 190 ... piezoelectric actuator

191,192 Lower electrode 193 Piezoelectric film

194 upper electrode 200 intermediate substrate

210 manifold 215 bulkhead

220 ... Restrictor 230 ... Damper

300 lower substrate 310 nozzle

311 Ink inlet 312 Ink outlet

Claims (35)

An upper substrate on which an ink inlet through which ink is introduced is formed, and on which a plurality of pressure chambers filled with ink to be discharged are formed; A manifold connected to the ink inlet, a plurality of restrictors connecting the manifold and one end of each of the plurality of pressure chambers, and a plurality of dampers connected to the other ends of each of the plurality of pressure chambers. Board; A lower substrate having a plurality of nozzles therethrough for discharging ink at a position corresponding to each of the plurality of dampers; And A piezoelectric actuator integrally formed on the upper substrate to provide a driving force for ejecting ink to each of the plurality of pressure chambers; The lower substrate, the intermediate substrate, and the upper substrate are all made of a single crystal silicon substrate, and are sequentially stacked and bonded to each other, so that the common flow path formed of the ink inlet and the manifold and the individual of the restrictor, the pressure chamber, the damper, and the nozzle are formed. Piezoelectric inkjet printhead, characterized in that the flow path is formed. The method of claim 1, An upper end of each of the manifold and the restrictor is defined by the upper substrate, and a lower end of each of the manifold and the restrictor is defined by the lower substrate. The method of claim 1, A piezoelectric inkjet printhead, wherein a portion of the upper substrate that forms the upper wall of the pressure chamber serves as a diaphragm flexurally deformed by driving the piezoelectric actuator. The method of claim 3, wherein The upper substrate is formed of an SOI wafer having a structure in which a first silicon substrate, an intermediate oxide film, and a second silicon substrate are sequentially stacked, the pressure chamber is formed on the first silicon substrate, and the second silicon substrate is A piezoelectric inkjet printhead, which serves as the diaphragm. The method of claim 1, The pressure chamber is a piezoelectric inkjet printhead, characterized in that arranged in two rows on both sides of the manifold. The method of claim 5, Piezoelectric inkjet printheads, characterized in that partitions are formed in the manifold in the longitudinal direction thereof. The method of claim 1, A piezoelectric inkjet printhead, wherein a silicon oxide film is formed between the upper substrate and the piezoelectric actuator. The piezoelectric actuator of claim 1, further comprising: a piezoelectric actuator; A lower electrode formed on the upper substrate, a piezoelectric film formed on the lower electrode to be positioned above the pressure chamber, and an upper electrode formed on the piezoelectric film to apply a voltage to the piezoelectric film. Piezoelectric inkjet printhead. The method of claim 8, The lower electrode has a piezoelectric inkjet printhead, characterized in that it has a two-layer structure in which a Ti layer and a Pt layer are sequentially stacked. The method of claim 1, And the nozzle includes an ink discharge port formed at a lower portion of the lower substrate, and an ink guide portion formed at an upper portion of the lower substrate to connect the damper and the ink discharge hole. The method of claim 10, And the ink guide portion gradually decreases in cross-sectional area from the damper toward the ink discharge port. The method of claim 11, The ink guide portion has a piezoelectric piezoelectric inkjet printhead, characterized in that the shape. Preparing an upper substrate, an intermediate substrate, and a lower substrate composed of a single crystal silicon substrate; An upper substrate processing step of finely processing the prepared upper substrate to form an ink inlet through which ink is introduced and a plurality of pressure chambers filled with ink to be ejected; By processing the prepared intermediate substrate finely, a manifold which is a common flow path connected to the ink inlet, a plurality of restrictors which are individual flow paths connecting the manifold and one end of each of the plurality of pressure chambers, and the plurality of pressures An intermediate substrate processing step of forming a plurality of dampers connected to the other ends of the chambers through the plurality of dampers; A lower substrate processing step of finely processing the prepared lower substrate so as to pass through a nozzle connected to the damper; Stacking and bonding the lower substrate, the intermediate substrate, and the upper substrate sequentially; And And forming a piezoelectric actuator on the upper substrate, the piezoelectric actuator providing a driving force for discharging ink. The method of claim 13, A method of manufacturing a piezoelectric inkjet printhead, further comprising forming a base mark on each of the three substrates to be used as an alignment criterion in the bonding step before the substrate processing step. The method of claim 14, The base mark forming step may include forming the base mark by etching at least the vicinity of the bottom edge of the upper substrate and the top and bottom edges of each of the intermediate substrate and the lower substrate to a predetermined depth. Method of manufacturing the head. The method of claim 15, The base mark is formed by wet etching using tetramethyl ammonium hydroxide (TMAH) or potassium hydroxide (KOH) as an etching solution. The method of claim 13, The method of manufacturing the piezoelectric inkjet printhead of the upper substrate may include forming the pressure chamber and the ink inlet by dry etching a bottom surface of the upper substrate to a predetermined depth. The method of claim 17, In the upper substrate processing step, an SOI wafer having a structure in which a first silicon substrate, an intermediate oxide film, and a second silicon substrate are sequentially stacked as the upper substrate is used, and the first oxide substrate is an etch stop layer. A method of manufacturing a piezoelectric inkjet printhead, characterized in that the pressure chamber and the ink inlet are formed by dry etching a silicon substrate. The method of claim 17, And the ink inlet formed at a predetermined depth on the bottom surface of the upper substrate passes through the pressure chamber forming step or the piezoelectric actuator forming step. The method of claim 13, In the intermediate substrate processing step, the piezoelectric inkjet printhead manufacturing method characterized in that to form the manifold, a plurality of restrictors and a plurality of dampers at the same time by the same processing step through the intermediate substrate. The method of claim 20, The intermediate substrate processing step is a piezoelectric inkjet printhead manufacturing method, characterized in that performed by dry etching by inductively coupled plasma (ICP). The method of claim 20, The intermediate substrate processing step, the piezoelectric inkjet printhead manufacturing method, characterized in that performed by sand blasting. The method of claim 22, A method of manufacturing a piezoelectric inkjet printhead, wherein a photoresist in the form of a dry film is applied onto the intermediate substrate before the sand blasting, as a protective film for protecting another portion of the intermediate substrate. The method of claim 13, In the intermediate substrate processing step, the piezoelectric inkjet printhead manufacturing method characterized in that the partition wall is formed in the longitudinal direction inside the manifold. The method of claim 13, wherein the lower substrate processing step; Etching the upper surface of the lower substrate to a predetermined depth to form an ink guide part connected to the damper; And etching the bottom surface of the lower substrate to form an ink ejection opening connected to the ink guide portion. The method of claim 25, In the forming of the ink guide portion, the piezoelectric inkjet is characterized by forming the ink guide portion having an inclined square pyramid shape by anisotropic wet etching the lower substrate using a (100) plane silicon substrate as the lower substrate. Method of manufacturing a printhead. The method of claim 13, In the bonding step, the piezoelectric inkjet printhead of claim 3, wherein the three substrates are laminated by a mask alignment device. The method of claim 13, In the bonding step, the bonding between the three substrates is a piezoelectric inkjet printhead manufacturing method, characterized in that carried out by a silicon direct bonding (SDB) method. The method of claim 28, In the bonding step, the three substrates are bonded to at least a bottom surface of the upper substrate and at least an upper surface of the lower substrate in a state that a silicon oxide film is formed in order to improve bonding between the three substrates. Method for producing an inkjet printhead of the type. The method of claim 13, And forming a silicon oxide film on the upper substrate before forming the piezoelectric actuator. The method of claim 13, wherein the forming of the piezoelectric actuator; Sequentially depositing a Ti layer and a Pt layer on the upper substrate to form a lower electrode; Forming a piezoelectric film on the lower electrode; A method of manufacturing a piezoelectric inkjet printhead, comprising: forming an upper electrode on the piezoelectric film. The method of claim 31, wherein The piezoelectric film forming step may include forming a piezoelectric film by coating a piezoelectric material in a paste state on the lower electrode at a position corresponding to the pressure chamber and then sintering the piezoelectric material. The method of claim 32, Coating of the piezoelectric material is a piezoelectric inkjet printhead manufacturing method, characterized in that performed by screen printing. The method of claim 32, A method of manufacturing a piezoelectric inkjet printhead, wherein an oxide film is formed on inner walls of the ink flow paths formed on the three substrates during sintering of the piezoelectric material. 32. The method of claim 31, wherein the piezoelectric actuator forming step comprises: A dicing step of cutting the three substrates in a bonded state after the upper electrode forming step; And a polling step of generating piezoelectric properties by applying an electric field to the piezoelectric film of the piezoelectric actuator.