KR100400228B1 - Inkjet printhead and manufacturing method thereof - Google Patents

Abstract

An inkjet printhead and a method of manufacturing the same are disclosed. The disclosed inkjet printhead comprises a substrate on which an ink chamber, a manifold and an ink channel are formed; A nozzle plate stacked on the substrate and having a nozzle formed thereon; Equipped. Here, the ink channel includes a first channel portion formed side by side on the surface of the substrate from the side of the manifold, and a second channel portion formed perpendicular to the surface of the substrate from the bottom surface of the ink chamber and connected to the first channel portion. . Therefore, it is possible to improve the ejection characteristics such as the ejection speed and the amount of droplets by reducing the backflow of the ink flowing out of the ink channel during the bubble growth.

Description

Inkjet printheads and manufacturing method thereof

The present invention relates to an inkjet printhead and a method of manufacturing the same, and more particularly, to a bubblejet inkjet printhead having an improved structure of an ink channel and a method of manufacturing the same.

The ink ejection method of the inkjet printer uses a heat source to generate bubbles (bubbles) in the ink and discharges the ink with this force, and an electro-thermal transducer (bubble jet method) and piezoelectric material using a piezoelectric body. There is an electro-mechanical transducer that ejects ink by volume change of the ink resulting from deformation.

The electro-thermal conversion method is classified into top-shooting, side-shooting, and back-shooting according to the direction of bubble growth and ejection of ink droplets. do. Here, the top-shooting method is a method in which the bubble growth direction and the ink droplet ejection direction are the same, and the side-shooting method is a method in which the bubble growth direction and the ink droplet ejection direction are perpendicular to each other. An ink ejection method in which the growth direction and the ejection direction of the ink droplets are opposite to each other.

Such a bubblejet inkjet printhead must satisfy the following requirements.

First, the production should be as simple as possible, inexpensive to manufacture, and capable of mass production.

Second, in order to obtain clear picture quality, the generation of fine satellite droplets smaller than the main droplets following the main droplets to be discharged should be suppressed as much as possible.

Third, when ejecting ink from one nozzle or refilling the ink into the ink chamber after ejecting the ink, cross talk with other adjacent nozzles that do not eject ink should be suppressed as much as possible. To this end, it is necessary to suppress a phenomenon in which ink flows back in a direction opposite to a nozzle during ink ejection.

Fourth, for high speed printing, the period of refilling after ink discharge should be as short as possible. In other words, the driving frequency should be high.

However, these requirements often conflict with each other, and the performance of the inkjet printhead is in turn closely related to the structure of the ink chamber, the ink flow path and the heater, and thus the formation and expansion of bubbles or the relative size of each element.

1 is a schematic cross-sectional view of one of the conventional inkjet printheads disclosed in US Pat. No. 6,019,457.

Referring to the drawings, a hemispherical ink chamber 15 is formed on an upper portion of the substrate 10 made of silicon or the like, and a manifold 16 that supplies ink to the ink chamber 15 is formed on the lower portion thereof. In the center of the bottom of the ink chamber 15, an ink channel 13 connecting the ink chamber 15 and the manifold 16 is formed.

On the surface of the substrate 10, a nozzle plate 20 having a nozzle 11 through which ink droplets 18 are discharged is positioned, forming an upper wall of the ink chamber 15. The nozzle plate 20 includes a thermal insulation layer 20a and a CVD chemical vapor deposition overcoat layer 20b thereon.

The nozzle plate 20 is provided with an annular heater 12 adjacent to and surrounding the nozzle 11, which is located at the interface between the insulating layer 20a and the overcoating layer 20b. On the other hand, the heater 12 is connected to an electric line (not shown) for applying a pulsed current.

In the above structure, when the pulsed current is applied to the annular heater 12 while the ink supplied through the manifold 16 and the ink channel 13 is filled in the ink chamber 15, the heater 12 Heat generated in the heat transfer) is transferred through the insulating layer 20a below, and ink below the heater 12 is boiled to generate bubbles B. Then, when the bubble B expands as the heat generated from the heater 12 continues, pressure is applied to the ink filled in the ink chamber 15 so that the ink near the nozzle 11 passes through the nozzle 11. It is discharged in the form of ink droplets 18 to the outside. Then, while the ink is sucked through the ink channel 13, the ink is filled again in the ink chamber 15.

As described above, the bubble jet inkjet printhead utilizes the principle that ink is ejected by the formation of bubbles by heat and the pressure generated as the bubbles grow.

However, in the conventional inkjet printhead as described above, since the ink channel 13 is in line with the nozzle 11, the pressure generated as the bubble B grows is not only the nozzle 11 side but also the ink chamber ( 15) The same also works toward the inlet to the ink flow into. Therefore, a back flow phenomenon of the ink occurs, and the performance of the inkjet printhead is degraded due to the back flow of the ink.

In order to solve the above problems, an object of the present invention is to provide an inkjet printhead and a method for manufacturing the same, which prevent backflow of ink by improving the structure of the ink channel.

1 is a cross-sectional view showing the structure of a conventional inkjet printhead.

2 is a schematic plan view of an inkjet printhead in accordance with the present invention.

3 is an enlarged plan view of portion A of FIG. 2;

4 is a cross-sectional view of the inkjet printhead taken along the line II of FIG. 3.

FIG. 5 is a cross-sectional view showing another example of the inkjet printhead seen along the line I-I of FIG. 3;

6 to 14 are cross-sectional views illustrating a process of manufacturing an inkjet printhead of the structure shown in FIG.

15 to 19 are cross-sectional views illustrating a process of manufacturing an inkjet printhead of the structure shown in FIG.

20 is a schematic plan view of another inkjet printhead in accordance with the present invention.

FIG. 21 is a sectional view of the inkjet printhead along the line II-II of FIG. 20;

<Brief description of symbols for the main parts of the drawings>

100 ... substrate 101 ... bonding pad

102 ... Manifold 103 ... Ink ejection

104 ... Nozzle 105 ... Ink Channel

105a ... first channel section 105b ... second channel section

106 ... ink chamber 108 ... heater

112 electrode 114 nozzle plate

116 ... heater protection layer 118 ... electrode protection layer

125 ... Nozzle Guide

In order to achieve the above object, the inkjet printhead according to the present invention,

An ink chamber filled with the ink to be discharged is formed on the surface thereof, and a manifold for supplying ink to the ink chamber is formed on the rear side thereof, and an ink channel connecting the ink chamber and the manifold includes: A substrate formed between the manifolds; And

A nozzle plate is stacked on the substrate, and a nozzle is formed at a position corresponding to a central portion of the ink chamber, and a heater formed to surround the nozzle and an electrode electrically connected to the heater to apply a current to the heater are disposed. With;

The ink channel may include a first channel portion formed parallel to the surface of the substrate from a side surface of the manifold, and a second channel formed perpendicularly to the surface of the substrate from a bottom surface of the ink chamber and connected to the first channel portion. It has a channel part.

Here, the ink chamber is substantially hemispherical in shape, and the first channel portion is formed parallel to the surface of the substrate from the side of the upper end of the manifold and is connected to the lower end of the second channel portion.

The nozzle plate may further include a nozzle guide extending from the edge of the nozzle in the depth direction of the ink chamber.

On the other hand, the manufacturing method of the inkjet printhead according to the present invention,

Forming a nozzle plate on which a heater and an electrode electrically connected to the heater are disposed on a surface of the substrate, and forming a nozzle on the nozzle plate; Etching the back surface of the substrate to a predetermined depth to form a manifold; Etching the substrate parallel to the surface of the substrate from a side surface of the manifold to form a first channel portion; Etching the substrate exposed by the nozzle to form an ink chamber; And etching the substrate perpendicularly to the surface of the substrate from a bottom surface of the ink chamber to form a second channel portion connected to the first channel portion.

In the step of forming the first channel portion, the first channel portion is formed by anisotropic wet etching the substrate parallel to the surface of the substrate from the side of the upper end of the manifold.

Forming the ink chamber includes forming the ink chamber substantially hemispherical by isotropically etching the substrate exposed by the nozzle.

On the other hand, another step of forming the ink chamber, anisotropically etching the substrate exposed by the nozzle to a predetermined depth to form a trench; Depositing a predetermined material layer to a predetermined thickness on the entire surface of the anisotropically etched substrate; Anisotropically etching the material film to expose a bottom of the trench and simultaneously forming a nozzle guide of the material film on sidewalls of the trench; And isotropically etching the substrate exposed at the bottom of the trench to form the substantially hemispherical ink chamber.

As described above, the present invention provides an inkjet printhead having an ink channel having an improved structure for preventing backflow of ink and a method of manufacturing the same.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments exemplified below are not intended to limit the scope of the present invention, but are provided to fully explain the present invention to those skilled in the art. Like reference numerals in the drawings refer to like elements, and the size or thickness of each element in the drawings may be exaggerated for convenience of explanation. 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.

First, FIG. 2 is a schematic plan view of a bubble jet inkjet printhead according to the present embodiment.

2, the inkjet printhead according to the present embodiment has two rows of ink ejecting portions 103 arranged on the manifold 102 for ink supply shown in dotted lines, and is electrically connected to each ink ejecting portion 103. Bonding pads 101 are arranged to be connected to each other and to which the wire is to be bonded. Manifold 102 is connected with an ink container (not shown) containing ink. Although the ink ejecting portions 103 are arranged in two rows in the drawing, they may be arranged in one row or may be arranged in three or more rows to further increase the resolution. In addition, one manifold 102 may be formed for each column of the ink ejecting portions 103. Further, although an inkjet printhead using only one color of ink is shown in the drawing, three or four groups of ink ejecting portions may be arranged for each color for color printing.

3 is an enlarged plan view of a portion A of FIG. 2, which is a feature of the present invention, and FIG. 4 is a cross-sectional view illustrating a vertical structure of the inkjet printhead along the line I-I of FIG.

The structure of the inkjet printhead according to the present embodiment will be described in detail with reference to FIGS. 3 and 4 as follows.

First, an ink chamber 106 in which ink is filled on a surface thereof is formed in a substantially hemispherical shape on the substrate 100, and a manifold 102 for supplying ink to each ink chamber 106 is formed on the back side thereof. It is. The substrate 100 is preferably made of silicon which is widely used in the manufacture of integrated circuits.

An ink channel 105 connecting the ink chamber 106 and the manifold 102 is formed between the ink chamber 106 and the manifold 102. Here, the ink channel 105 is composed of a first channel portion 105a and a second channel portion 105b. The first channel portion 105a is formed parallel to the surface of the substrate 100 from the side of the manifold 102, and the second channel portion 105b is formed from the bottom surface of the ink chamber 106. It is formed perpendicular to the surface of the is connected to the first channel portion 105a. Here, the first channel portion 105a, which is a feature of the present invention, serves to prevent backflow of ink. The substrate 100 may be parallel to the surface of the substrate 100 from the side of the upper end of the manifold 102. It is formed by anisotropic etching and is connected to the lower end of the second channel portion 105b. Here, the method in which the first channel portion 105a is formed side by side on the surface of the substrate 100 from the side surface of the upper end portion of the manifold 102 will be described later.

The nozzle plate 114 is stacked on the surface of the substrate 100 to form an upper wall of the ink chamber 106, and the nozzle plate 114 is positioned at a position corresponding to the central portion of the ink chamber 106. Is formed. When the substrate 100 is made of silicon, the nozzle plate 114 may be made of a silicon oxide film formed by oxidizing the silicon substrate, or may be made of an insulating film such as a silicon nitride film deposited on the substrate.

An annular bubble generating heater 108 is formed on the nozzle plate 114 to surround the nozzle 104. The heater 108 is made of a resistive heating element such as polycrystalline silicon or tantalum-aluminum alloy doped with impurities, and an electrode 112 for applying a pulsed current is connected to the heater 108. This electrode 112 is usually made of the same material as the bonding pad (101 in FIG. 2) and the necessary wiring (not shown), for example metal such as aluminum or aluminum alloy. Meanwhile, in order to protect the heater 108 and the electrode 112, the heater protection layer 116 and the electrode protection layer 118 are formed on the heater 108 and the electrode 112, respectively.

In such a structure, when a pulsed current is applied to the annular heater 108 while the ink supplied through the ink channel 105 from the manifold 102 is filled in the ink chamber 106 by capillary action, Heat generated in the heater 108 is transferred through the nozzle plate 114 below and the ink below the heater 108 is boiled to generate bubbles B '. At this time, the shape of the bubble B 'becomes approximately a donut shape.

As the bubble B 'expands over time, the ink in the ink chamber 106 is discharged through the nozzle 104 by the pressure of the expanding bubble B'. In this case, the expanding bubble B ′ also applies pressure toward the ink channel 105 through which ink enters the ink chamber 106. However, the ink channel 105 is formed on the surface of the substrate 100 from the bottom surface of the ink chamber 106 and the first channel portion 105a formed side by side on the surface of the substrate 100 from the side of the manifold 102. Since the second channel portion 105b is formed vertically and is connected to the first channel portion 105a at right angles, the direction of the ink flow passing through the inside of the ink channel 105 is bent at right angles. Therefore, the phenomenon in which the ink in the ink chamber 106 flows back toward the manifold 102 at the time of ink discharge can be prevented.

When the current applied to the next block is cut off, the bubble B 'is reduced or burst before it is cooled, and ink is filled in the ink chamber 106 again.

5 is a cross-sectional view of an inkjet printhead according to another embodiment of the present invention, which is different from the printhead shown in FIG. 4, in which the nozzle guide 125 has an ink chamber 106 from the edge of the nozzle 104. It extends toward the side. The nozzle guide 125 guides the ejection direction of the droplet during bubble B 'growth, so that the droplet is ejected in a direction perpendicular to the substrate 100.

Next, a method of manufacturing the inkjet printhead of the present invention will be described.

6 to 14 are cross-sectional views illustrating a process of manufacturing an inkjet printhead of the structure shown in FIG. 4.

FIG. 6 illustrates a state in which a nozzle plate is formed on a surface of a substrate, a heater is formed thereon, a heater protective layer is deposited on the front surface, an electrode is formed, and an electrode protective layer is deposited on the front surface again. It is.

First, in this embodiment, the substrate 100 uses a silicon substrate having a crystal plane of (111). The reason for using a silicon substrate is that a silicon wafer widely used in the manufacture of semiconductor devices can be used as it is and is effective for mass production.

Subsequently, when the silicon substrate 100 is placed in an oxidation furnace and wet or dry oxidized, a silicon oxide film that becomes the nozzle plate 114 is formed on the surface of the silicon substrate 100, and a nozzle is formed on the nozzle plate 114 later. do.

Next, the annular heater 108 is formed on the nozzle plate 114. The heater 108 is formed by depositing polycrystalline silicon or the like doped with impurities on the nozzle plate 114, which is a silicon oxide film, and then patterning it in an annular shape.

Next, a heater protection layer 116 such as a silicon nitride film is deposited on the entire surface of the nozzle plate 114 on which the annular heater 108 is formed, and the heater protection layer 116 deposited on the heater 108 is etched to form an electrode. The heater 108 of the portion to be connected with 112 is exposed. Subsequently, the electrode 112 is formed by depositing and patterning a metal having good conductivity and easy patterning, such as aluminum or an aluminum alloy. In this case, the metal film constituting the electrode 112 is patterned to simultaneously form a wiring (not shown) and a bonding pad (101 in FIG. 2) at other portions of the substrate 100. Next, an electrode protective layer 118 such as a tetraethylerthosilane (TEOS) oxide film is deposited on the entire surface of the substrate 100 on which the electrode 112 is formed.

FIG. 7 illustrates a state in which a nozzle is formed in the state shown in FIG. 6. Specifically, the electrode protection layer 118, the heater protection layer 116, and the nozzle plate 114 are sequentially etched to a diameter smaller than the diameter of the heater 108 to the inside of the heater 108 to form the nozzle 104. The substrate 100 is exposed.

8 illustrates a state in which a manifold is formed by etching the back surface of a substrate. Specifically, first, an etching mask material 201 such as a silicon oxide film is deposited on the back surface of the silicon substrate 100, and then patterned to form an etching mask defining a region to be etched. Next, the silicon substrate 100 exposed by the etching mask is wet or dry etched to a predetermined depth to form the manifold 102.

Next, as shown in FIGS. 9 and 10, the etch mask material 203 such as a silicon oxide film is redeposited on the entire surface of the silicon substrate 100 on which the manifold 102 is formed, and then the etch mask material is deposited. The 203 is etched perpendicularly to the surface of the substrate 100 to expose the silicon substrate 100. At this time, the etching mask material 203 on the side of the manifold 102 is left as it is due to the etching characteristics.

Subsequently, as shown in FIG. 11, the silicon substrate 100 exposed in the state shown in FIG. 10 is etched perpendicularly to the surface of the substrate 100 to a predetermined depth. At this time, the depth to be etched determines the height of the ink channel.

Next, wet etching the portion 240 etched to a predetermined depth of FIG. 11 with a general silicon anisotropic etchant such as tetramethyl ammonium hydroxide (TMAH), KOH, etc. As shown in FIG. 12, first channel portions 105a that are flat in a direction parallel to the surface of the substrate 100 are formed from both side surfaces of the upper end of the manifold 102. Here, the reason why the first channel portion 105a having the shape as shown in FIG. 12 is formed is that the rate at which silicon is etched in a direction parallel to the surface of the substrate 100 in the silicon substrate having a crystal plane of (111) is shown in FIG. This is because it is faster than the speed of etching in the direction perpendicular to the surface. Next, as shown in FIG. 13, the ink chamber 106 is formed by isotropically etching the substrate 100 exposed by the nozzle 104. At this time, the shape of the ink chamber 106 becomes substantially hemispherical.

Finally, the second channel portion 105b is formed by anisotropically etching the substrate 100 exposed by the nozzle 104 in the state shown in FIG. 13. The second channel portion 105b is formed perpendicular to the surface of the substrate 100 from the bottom surface of the ink chamber 106 and connected to the first channel portion 105a described above.

15 to 19 are cross-sectional views illustrating a process of manufacturing the inkjet printhead of the structure shown in FIG.

The manufacturing method of the inkjet printhead shown in FIG. 5 is the same as the manufacturing method of the inkjet printhead shown in FIG. 4, except that the step of forming the nozzle guide is added. That is, the steps up to the steps shown in FIG. 12 are the same, and in the subsequent steps, the step of forming the nozzle guide is added. Therefore, the following description will focus on the step of forming the nozzle guide.

In the state shown in FIG. 12, the substrate 100 exposed by the nozzle 104 is anisotropically etched to form the trench 140 having a predetermined depth as shown in FIG. 15. Subsequently, a predetermined material layer 142, such as a TEOS oxide film, is deposited on its front surface as shown in FIG. Next, when the material layer 142 is anisotropically etched until the substrate 100 is exposed, the nozzle guide 125 is formed on the sidewall of the trench 140 as shown in FIG. 17.

Next, as described above, the ink chamber 106 is formed as shown in FIG. 18 by isotropic etching the substrate 100 exposed by the nozzle 104 in the state shown in FIG. In the illustrated state, the substrate 100 exposed by the nozzle 104 is anisotropically etched to form the second channel portion 105b as shown in FIG. 19.

On the other hand, the inkjet printhead having the above structure may use a silicon wafer having a crystal plane of (100) in addition to the silicon wafer having a crystal plane of (111) described above as a substrate.

FIG. 20 is a schematic plan view of the inkjet printhead when a silicon wafer having a crystal plane of (100) is used as the substrate, and FIG. 21 is a sectional view showing the vertical structure of the inkjet printhead along the II-II line of FIG.

In the case of using the silicon substrate 100 whose crystal plane is (100), the pattern on the silicon substrate 100 is arranged at 45 ° as shown in FIG. In this way, the first channel portion 105a ′ parallel to the surface of the substrate 100 may be formed from both sides of the upper end of the manifold 102 due to the 45 ° etching characteristic of the silicon substrate 100 having the crystal surface (100).

The first channel portion 105a ′ is formed as shown in FIG. 21. In the silicon substrate 100 having the crystal plane of 100, the speed at which silicon is etched in a direction parallel to the surface of the substrate 100 is increased. This is because the speed is similar to the speed of etching in the direction perpendicular to the surface of the substrate 100.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and equivalent other embodiments are possible.

Therefore, in the present invention, the materials used to construct each element of the inkjet printhead may use materials that are not illustrated, and also methods of laminating and forming each material are merely illustrated, and various deposition methods and etching methods may be applied. Can be.

Further, in the inkjet printhead manufacturing method of the present invention, the order of each step may be different from that illustrated in some cases.

As described above, the inkjet printhead according to the present invention has a first channel portion formed side by side on the surface of the substrate from the side of the manifold, and is formed perpendicular to the surface of the substrate from the bottom surface of the ink chamber, so that the first channel The second channel portion connected at right angles to the portion causes the flow of ink in the ink channel to be bent at right angles. Therefore, it is possible to prevent the phenomenon in which ink in the ink chamber flows back toward the manifold during ink ejection.

Claims (8)

An ink chamber filled with ink to be discharged is formed on the surface side thereof, and a manifold for supplying ink to the ink chamber is formed on the rear side thereof, and an ink channel connecting the ink chamber and the manifold includes: A substrate formed between the manifolds; And A nozzle plate is stacked on the substrate, and a nozzle is formed at a position corresponding to a central portion of the ink chamber, and a heater formed to surround the nozzle and an electrode electrically connected to the heater to apply a current to the heater are disposed. With; The ink channel may include a first channel portion formed parallel to the surface of the substrate from a side surface of the manifold, and a second channel formed perpendicularly to the surface of the substrate from a bottom surface of the ink chamber and connected to the first channel portion. An inkjet printhead comprising a channel portion. The method of claim 1, And the ink chamber is substantially hemispherical in shape. The method according to claim 1 or 2, The first channel portion is formed side by side on the surface of the substrate from the side of the upper end of the manifold, the inkjet printhead, characterized in that connected to the lower end of the second channel portion. The method according to claim 1 or 2, The nozzle plate further comprises a nozzle guide extending from the edge of the nozzle in the depth direction of the ink chamber. Forming a nozzle plate on which a heater and an electrode electrically connected to the heater are disposed on a surface of the substrate, and forming a nozzle on the nozzle plate; Etching the back surface of the substrate to a predetermined depth to form a manifold; Etching the substrate parallel to the surface of the substrate from a side surface of the manifold to form a first channel portion; Etching the substrate exposed by the nozzle to form an ink chamber; And And etching the substrate perpendicularly to the surface of the substrate from a bottom surface of the ink chamber to form a second channel portion connected to the first channel portion. The method of claim 5, In the forming of the first channel portion, the first channel portion is formed by anisotropic wet etching the substrate parallel to the surface of the substrate from the side of the upper end of the manifold inkjet printhead manufacturing method. The method according to claim 5 or 6, And forming the ink chamber comprises forming the substantially hemispherical ink chamber by isotropically etching the substrate exposed by the nozzle. The method according to claim 5 or 6, Forming the ink chamber, Anisotropically etching the substrate exposed by the nozzle to a predetermined depth to form a trench; Depositing a predetermined material layer to a predetermined thickness on the entire surface of the anisotropically etched substrate; Anisotropically etching the material film to expose a bottom of the trench and simultaneously forming a nozzle guide of the material film on sidewalls of the trench; And Forming the substantially hemispherical ink chamber by isotropically etching the substrate exposed at the bottom of the trench.