KR100590527B1 - Inkjet printhead and manufacturing method thereof - Google Patents

Abstract

An inkjet printhead and a method of manufacturing the same are disclosed. In the disclosed inkjet printhead, an ink chamber filled with ink to be discharged is formed on the surface thereof, a manifold for supplying ink to the ink chamber is formed on the rear side thereof, and an ink flow path connecting the ink chamber and the manifold is formed. A substrate formed side by side on the surface; A nozzle plate stacked on a substrate and comprising a plurality of protective layers made of an insulating material, and a heat dissipating layer stacked on the protective layer and made of a thermally conductive metal material, the nozzle plate being formed through the nozzle connected to the ink chamber; And a heater disposed between the protective layers of the nozzle plate and positioned above the ink chamber to heat the ink in the ink chamber, and a conductor to apply a current to the heater.

Description

Inkjet printheads and manufacturing method thereof

1 is a perspective view showing an example of a conventional inkjet printhead.

2 is a perspective view showing another example of a conventional inkjet printhead.

3 is a perspective view showing another example of a conventional inkjet printhead.

4 is a schematic plan view of an inkjet printhead according to an embodiment of the invention.

5 is an enlarged plan view of portion A of FIG. 4;

FIG. 6 is a sectional view of the inkjet printhead along the VI-VI line of FIG. 5; FIG.

7 is a partial perspective view of a substrate on which an ink chamber and an ink passage are formed.

8 to 19 are views illustrating a process of manufacturing an inkjet printhead according to an embodiment of the present invention.

20 and 22 are cross-sectional views showing another process of manufacturing the inkjet printhead according to the present invention.

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

100 ... substrate 101 ... bonding pad

102 ... Manifold 103 ... Ink ejection

104 ... Nozzle 104a ... Lower Nozzle

104b ... Top nozzle 105 ... Ink flow path

105a ... ink channel 105b ... ink feed hole

106 ... ink chamber 108 ... heater

112 ... conductor 120 ... nozzle plate

121,122,126 ... 1st, 2nd, 3rd protective layer

127,127 '... seed layer 128 ... heat dissipation layer

250,250 '... sacrificial layer 300 ... SOI substrate

350 ... lower plating frame 450 ... upper plating frame

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printhead and a method of manufacturing the same, and in particular, the ejection performance can be improved by forming the ink flow path on the same plane as the ink chamber, and the liquid ejected through the nozzle by providing a metal nozzle plate on the substrate. The present invention relates to an inkjet printhead and a method of manufacturing the same, which improves straightness of an enemy and effectively radiates heat generated from a heater to improve driving frequency.

In general, an inkjet printhead is an apparatus for ejecting a small droplet of printing ink to a desired position on a recording sheet to print an image of a predetermined color. Such inkjet printheads can be largely classified in two ways depending on the ejection mechanism of the ink droplets. One is a heat-driven inkjet printhead which generates bubbles in the ink by using a heat source and ejects ink droplets by the expansion force of the bubbles, and the other is ink due to deformation of the piezoelectric body using a piezoelectric body. A piezoelectric drive inkjet printhead which discharges ink droplets by a pressure applied thereto.

The ink droplet ejection mechanism of the thermally driven inkjet printhead will be described in detail as follows. When a pulse current flows through a heater made of a resistive heating element, heat is generated in the heater and the ink adjacent to the heater is instantaneously heated to approximately 300 ° C. As a result, bubbles are generated while the ink is boiled, and the generated bubbles expand to apply pressure to the ink chamber filled with the ink. As a result, the ink near the nozzle is discharged out of the ink chamber in the form of droplets through the nozzle.

Here, the thermal driving method is further classified into a top-shooting, side-shooting, and back-shooting method according to the bubble growth direction and the ink droplet ejection direction. Can be. In the top-shooting method, the growth direction of the bubble and the ejection direction of the ink droplets are the same. In the side-shooting method, the growth direction of the bubble and the ejection direction of the ink droplets are perpendicular to each other. An ink droplet ejecting method in which the growth direction and the ejecting direction of the ink droplets are opposite to each other.

Such thermally driven inkjet printheads generally must meet 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 a high quality image, the distance between adjacent nozzles should be as narrow as possible while suppressing cross talk between adjacent nozzles. In other words, to increase dots per inch (DPI), it is necessary to be able to place a large number of nozzles at high density. Third, for high speed printing, the period during which ink is refilled in the ink chamber after the ink is ejected from the ink chamber should be as short as possible. In other words, the heated ink must be cooled quickly to increase the driving frequency.

1 is a perspective view illustrating a structure of an inkjet printhead disclosed in US Pat. No. 5,502,471 as an example of a conventional back-shooting inkjet printhead. Referring to the drawings, the inkjet printhead 24 includes a substrate 11, an ink chamber 16, and an ink reservoir 12 in which a nozzle 10 through which ink droplets are ejected and an ink chamber 16 in which ink to be ejected is filled. ) Has a structure in which a cover plate 3 having a through hole 2 connecting thereon and an ink reservoir 12 for supplying ink to the ink chamber 16 are sequentially stacked. Here, the heater 42 is annularly arranged around the nozzle 10 of the substrate 11.

In the above structure, when the current in the form of a pulse is supplied to the heater 42 to generate heat in the heater 42, the ink in the ink chamber 16 boils and bubbles are generated. The generated bubbles continue to expand, whereby pressure is applied to the ink filled in the ink chamber 16 so that the ink droplets are discharged to the outside through the nozzle 10. Next, ink is sucked into the ink chamber 16 through the through hole 2 formed in the cover plate 3 from the ink reservoir 12, and the ink chamber 16 is again filled with ink.

However, in such an inkjet printhead, the height of the ink chamber is almost equal to the thickness of the substrate, so that the size of the ink chamber becomes large unless a very thin substrate is used. Therefore, a phenomenon occurs in which the pressure of the bubble to be used for ejecting the ink is dispersed by the surrounding ink, resulting in poor ejection characteristics. On the other hand, when a thin substrate is used to reduce the size of the ink chamber, it becomes difficult to process the substrate. That is, the height of the ink chamber generally used in the current inkjet printhead is about 10 to 30 µm, and a silicon substrate of about 10 to 30 µm must be used to form an ink chamber having such a height. However, it is not possible to process silicon substrates of this thickness in semiconductor processes.

On the other hand, in order to manufacture the inkjet printhead of the above structure, the substrate, the cover plate and the ink reservoir must be bonded. Therefore, the manufacturing process becomes complicated, and there is a problem in that the ink flow path, which is an element that affects the discharge characteristics sensitively, cannot be formed precisely.

2 is a cross-sectional view showing the structure of the inkjet printhead disclosed in US Pat. No. 5,841,452 as another example of the conventional back-shooting inkjet printhead. Referring to the drawings, a hemispherical ink chamber 15 is formed on an upper portion of the substrate 30 made of silicon or the like, and a manifold 26 that supplies ink to the ink chamber 15 is formed on the lower portion thereof. The ink channel 13 connecting the ink chamber 15 and the manifold 26 is formed in a cylindrical shape perpendicular to the surface of the substrate 30 between the ink chamber 15 and the manifold 26. The nozzle plate 20 on which the nozzle 21 from which the ink droplets 18 are discharged is formed is located on the surface of the substrate 30 to form an upper wall of the ink chamber 15. The nozzle plate 20 is formed with an annular heater 22 adjacent to and surrounding the nozzle 21, and an electric line (not shown) for applying a current is connected to the heater 22.

In the above structure, when the ink supplied through the manifold 26 and the ink channel 13 is filled in the ink chamber 15, when the pulse type current is applied to the annular heater 22, the heater 22 By the heat generated in the ink under the heater 22 boils and bubbles are generated. As a result, pressure is applied to the ink filled in the ink chamber 15, and the ink near the nozzle 21 is discharged to the outside through the nozzle 21 in the form of an ink droplet 18. Next, while ink is sucked through the ink channel 13, the ink is refilled in the ink chamber 15.

In such an inkjet printhead, since only a part of the substrate is etched to form an ink chamber, the size of the ink chamber can be reduced, and the manufacturing process is simple since the printhead is manufactured in a batch process without a bonding process.

However, since the ink channel is located in line with the nozzle, the back flow of the ink occurs when bubbles are generated, resulting in poor discharge characteristics. Further, since the ink chamber is formed by etching the substrate exposed by the nozzle, the size of the ink chamber can be reduced, but there is a disadvantage in that an ink chamber having an arbitrary shape cannot be manufactured. Therefore, it is difficult to make an ink chamber having an optimal shape.

3 is a schematic cross-sectional view showing the structure of the inkjet printhead disclosed in US Pat. No. 6,382,782 as another example of a conventional back-shooting inkjet printhead. Referring to the drawings, the inkjet printhead supplies ink to the nozzle plate 50 on which the nozzle 51 is formed, the insulating layer 60 on which the ink chamber 61 and the ink channel 62 are formed, and the ink chamber 61. The silicon substrate 70 on which the manifold 55 is formed is sequentially stacked.

In such an inkjet printhead, by forming an ink chamber using an insulating layer laminated on a substrate, the shape of the ink chamber can be arbitrarily reduced, and the backflow phenomenon can be reduced.

However, in the manufacture of such an inkjet printhead, a method of depositing a thick insulating layer on a silicon substrate and etching the same to form an ink chamber is generally used, which has the following problems. First, it is difficult to stack a thick insulating layer on a substrate in the existing semiconductor process, and second, it is difficult to etch a thick insulating layer. Therefore, in such an inkjet printhead, there is a certain limit to the height of the ink chamber, so that an ink chamber and a nozzle of about 6 mu m are shown in FIG. However, at this height of the ink chamber, it is impossible to produce an inkjet printhead having a relatively large drop size.

The present invention has been devised to solve the above problems, and by forming the ink flow path on the same plane as the ink chamber, the ejection performance can be improved, and by providing a metal nozzle plate on the substrate, SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet printhead having an improved structure and a method of manufacturing the same, which can improve straightness and effectively dissipate heat generated from a heater to improve driving frequency.

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 side thereof, a manifold for supplying ink to the ink chamber is formed on the rear side thereof, and an ink flow path connecting the ink chamber and the manifold is parallel to the surface thereof. A substrate formed;

A nozzle plate laminated on the substrate and comprising a plurality of protective layers made of an insulating material, and a heat dissipating layer stacked on the protective layer and made of a thermally conductive metal material, the nozzle plate being formed through the nozzle connected to the ink chamber; And

And a heater disposed between the passivation layers of the nozzle plate and positioned above the ink chamber to heat the ink in the ink chamber, and a conductor to apply a current to the heater.

Preferably, the ink flow path is formed on the same plane as the ink chamber, wherein the ink flow path includes at least one ink channel connected to the ink chamber, and an ink feed hole connecting the ink channel and the manifold. It is provided.

The passivation layers include a first passivation layer, a second passivation layer, and a third passivation layer sequentially stacked on the substrate, and the heater is provided between the first passivation layer and the second passivation layer. The conductor is provided between the second protective layer and the third protective layer.

A lower portion of the nozzle is formed in the plurality of protective layers, and an upper portion of the nozzle is formed in the heat dissipating layer.

It is preferable that the upper portion of the nozzle formed in the heat dissipating layer has a tapered shape in which the cross-sectional area decreases toward the outlet.

The heat dissipation layer may include at least one metal layer, and each of the metal layers may be made of any one metal material selected from the group consisting of nickel, copper, aluminum, and gold. Here, the heat dissipation layer is preferably formed to a thickness of 10 ~ 100㎛ by electroplating.

A seed layer for electroplating the heat dissipation layer may be formed on the passivation layers. Here, the seed layer is made of at least one metal layer, each of the metal layer may be made of any one metal material selected from the group consisting of copper, chromium, titanium, gold and nickel.

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

Forming a sacrificial layer of a predetermined depth toward the surface of the substrate;

Sequentially stacking a plurality of protective layers on the substrate on which the sacrificial layer is formed, forming a heater and a conductor connected to the heater between the protective layers;

Forming a heat dissipation layer made of metal on the passivation layers, and forming a nozzle through which the ink is discharged to pass through the heat dissipation layer and the passivation layers to expose the sacrificial layer;

Forming a manifold for supplying ink to the back side of the substrate;

Removing the sacrificial layer exposed through the nozzle to form an ink chamber and an ink flow path; And

Connecting the manifold and the ink flow path.

The forming of the sacrificial layer may include forming a groove having a predetermined depth by etching the surface of the substrate; Oxidizing a surface of the substrate on which the groove is formed to form an oxide layer; And filling a predetermined material in the groove, and then planarizing the surface of the substrate. Here, the filling of the predetermined material in the groove is preferably a step of epitaxially growing polysilicon in the groove.

The forming of the sacrificial layer may include forming a trench having a predetermined shape in the upper silicon substrate of the SOI substrate; And filling a predetermined material in the trench. Here, the predetermined material is preferably silicon oxide.

The forming of the protective layers may include forming a first protective layer on a surface of the substrate on which the sacrificial layer is formed; Forming the heater on the first protective layer; Forming a second passivation layer on the first passivation layer and the heater; Forming the conductor on the second protective layer; And forming a third protective layer over the second protective layer and the conductor.

The heat dissipation layer is formed of at least one metal layer, and each of the metal layers may be formed by electroplating any one metal material selected from the group consisting of nickel, copper, aluminum, and gold. Here, the heat dissipation layer is preferably formed to a thickness of 10 ~ 100㎛.

The forming of the heat dissipation layer and the nozzle may include forming a lower nozzle by etching the protective layers on the sacrificial layer; Forming a lower plating mold in the lower nozzle; Forming an upper plating mold having a predetermined shape for forming an upper nozzle on the lower plating mold; Forming the heat dissipating layer on the passivation layers by electroplating; And removing the upper and lower plating molds to form a nozzle including the upper nozzle and the lower nozzle. Here, the lower plating frame and the upper plating frame is preferably made of a photoresist or photosensitive polymer.

The forming of the heat dissipation layer and the nozzle may include forming a lower nozzle by etching the protective layers on the sacrificial layer; Forming a plating mold having a predetermined shape for forming an upper nozzle in a vertical direction from the inside of the lower nozzle; Forming the heat dissipating layer on the passivation layers by electroplating; And removing the plating mold to form the nozzle including the upper nozzle and the lower nozzle. Here, the plating frame is preferably made of a photoresist or photosensitive polymer.

The lower nozzle may be formed by dry etching the protective layers by reactive ion etching.

It is preferable to form a seed layer for electroplating the heat dissipation layer on the protective layers. The seed layer may include at least one metal layer, and each of the metal layers may be formed by depositing any one metal material selected from the group consisting of copper, chromium, titanium, gold, and nickel.

After the step of forming the heat dissipating layer, it is preferable to planarize the upper surface of the heat dissipating layer by a chemical mechanical polishing process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 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.

4 is a schematic plan view of an inkjet printhead according to the present invention. Referring to FIG. 4, in the inkjet printhead, the ink ejecting portions 103 are arranged in two rows, and bonding pads 101 to be electrically connected to the respective ink ejecting portions 103 are disposed. 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.

FIG. 5 is an enlarged plan view of portion A of FIG. 4, and FIG. 6 is a cross-sectional view illustrating a vertical structure of the inkjet printhead viewed along the line VI-VI of FIG. 5, and FIG. 7 is an ink formed on the surface of the substrate. A partial perspective view of a substrate showing the chamber and the ink flow path.

Referring to the drawings, the substrate 100 of the inkjet printhead is formed with an ink chamber 106 filled with ink to be discharged on a surface thereof to a predetermined depth, and on the back side thereof for supplying ink to the ink chamber 106. Manifold 102 is formed.

Here, since the ink chamber 106 and the manifold 102 are formed by etching the surface and the back surface of the substrate 100, the shapes thereof may be variously modified. Here, the ink chamber 106 is preferably formed to a depth of approximately 10 ~ 80㎛. The manifold 102 formed below the ink chamber 106 is connected to an ink reservoir (not shown) containing ink.

Between the ink chamber 106 and the manifold 102, an ink flow path 105 connecting them to each other is formed on the surface side of the substrate 100. Here, the ink flow path 105 is formed by etching the surface of the substrate 100 similarly to the ink chamber 106. Therefore, the shape of the ink flow path 105 may also be variously modified. The ink flow path 105 is formed in parallel with the surface of the substrate 100 on the same plane as the ink chamber 106. The ink flow path 105 is composed of an ink channel 105a and an ink feed hole 105b, the ink channel 105a is connected to an ink chamber 106, and the ink feed hole 105b is a manifold 102. ). Meanwhile, the ink channel 105a may be formed in plural in consideration of discharge characteristics.

A nozzle plate 120 is provided on the substrate 100 on which the ink chamber 106, the ink flow path 105, and the manifold 102 are formed. The nozzle plate 120 forms an upper wall of the ink chamber 106 and the ink flow path 105. The nozzle plate 120 is formed by vertically penetrating a nozzle 104 through which ink is discharged from the ink chamber 106.

The nozzle plate 120 is composed of a plurality of material layers stacked on the substrate 100. These material layers include first, second and third protective layers 121, 122, 126 and a heat dissipation layer 128 made of metal. A heater 108 is provided between the first protective layer 121 and the second protective layer 122, and a conductor (FIG. 5) is provided between the second protective layer 122 and the third protective layer 126. 112) is provided.

The first passivation layer 121 is formed on the upper surface of the substrate 100 as a material layer at the bottom of the plurality of material layers constituting the nozzle plate 120. The first protective layer 121 may be formed of silicon oxide or silicon nitride as a material layer for insulation between the heater 108 and the substrate 100 and for protecting the heater 108.

On the first protective layer 121 of the upper portion of the ink chamber 106, a heater 108 for heating ink in the ink chamber 106 is formed. The heater 108 may be formed in plural, and the position or shape of the heater 108 may be different from that shown in the drawing. Thus, the heater 108 may be formed in an annular shape surrounding the nozzle 104. The heater 108 is made of a heat generating resistor such as polysilicon, tantalum-aluminum alloy, tantalum nitride, titanium nitride or tungsten silicide doped with impurities.

The second passivation layer 122 is provided on the first passivation layer 121 and the heater 108. The second passivation layer 122 is provided to protect the heater 108 and may be made of silicon nitride or silicon oxide similarly to the first passivation layer 121.

Although not shown in FIG. 6, a conductor (112 of FIG. 5) is provided on the second protective layer 122 to be electrically connected to the heater 108 to apply a pulse current to the heater 108. One end of the conductor 112 of FIG. 5 is connected to the heater 108 through a contact hole (not shown) formed on the second protective layer 122, and the other end thereof is electrically connected to the bonding pad (101 of FIG. 4). Is connected. The conductor 112 of FIG. 5 may be made of a metal having good electrical and thermal conductivity, such as aluminum or an aluminum alloy, or gold or silver.

The third protective layer 126 is provided on the conductor 112 (in FIG. 5) and the second protective layer 122. The third protective layer 126 may be made of tetraethylorthosilicate (TEOS) oxide or silicon oxide.

The heat dissipation layer 128 is a top material layer of the plurality of material layers constituting the nozzle plate 120. The heat dissipation layer 128 may be made of a metal having good thermal conductivity, such as nickel (Ni), copper (Cu), aluminum (Al), or gold (Au). In addition, the heat dissipation layer 128 may be formed of a plurality of metal layers. The heat dissipation layer 128 may be formed to a thickness of about 10 ~ 100㎛ by the electroplating of the metal material. To this end, a seed layer 127 for electroplating the metal material is provided on both the upper surface of the third protective layer 126 and the surface of the substrate 100. The seed layer 127 may be made of a metal having good conductivity, such as copper (Cu), chromium (Cr), titanium (Ti), gold (Au), or nickel (Ni). In addition, the seed layer 127 may be formed of a plurality of metal layers.

The heat dissipation layer 128 functions to dissipate heat to the heater 108 and its surroundings to the outside. That is, the heat remaining in the heater 108 and its surroundings after the ink is discharged is emitted to the substrate 100 and the outside through the heat dissipation layer 128. Therefore, since the heat dissipation is made faster after the ink is discharged and the temperature around the nozzle 104 is lowered, stable printing is possible at a high driving frequency.

As described above, since the heat dissipation layer 128 may be formed to a relatively thick thickness, the length of the nozzle 104 may be sufficiently long. Therefore, stable high speed printing is enabled, and the straightness of the ink droplets discharged through the nozzle 104 is improved. That is, the ejected ink droplets may be ejected in a direction that is exactly perpendicular to the substrate 100.

On the other hand, the nozzle 104 is composed of a lower nozzle 104a and an upper nozzle 104b. The lower nozzle 104a is formed in a cylindrical shape in the first, second, and third protective layers 121, 122, 126, and the upper nozzle 104b has a diameter toward the outlet of the heat dissipating layer 128. It is formed in a tapered shape that becomes smaller. Thus, when the upper nozzle 104b is formed in a tapered shape, there is an advantage that the meniscus on the surface of the ink is stabilized more quickly after the ejection of the ink.

In the inkjet printhead having the above structure, a mechanism in which ink is discharged through the nozzle 104 will be described.

First, in a state where ink is filled in the ink chamber 106 and the nozzle 104, heat is generated in the heater 108 when a pulse current is applied to the heater 108 through the conductor 112. The heat generated in this way is transferred to the ink in the ink chamber 106 through the first protective layer 121 under the heater 108, whereby the ink boils and bubbles are generated. The generated bubbles expand with the continuous supply of heat, so that the ink inside the nozzle 104 is pushed out of the nozzle 104.

Then, when the applied current is interrupted, the bubble contracts and disappears. At this time, the ink pushed out of the nozzle 104 is discharged in the form of droplets. On the other hand, since the heat remaining in the heater 108 and its surroundings after discharge of the ink droplets is dissipated to the substrate 100 and the outside through the heat dissipating layer 128, the temperature of the heater 108 and its surroundings is rapidly lowered. do.

Next, the interior of the ink chamber 106 is again filled with ink supplied from the manifold 102 through the ink channel 105a and the ink feed hole 105b. When the refilling of the ink is completed and returned to the initial state, the above process is repeated.

In the inkjet printhead according to the embodiment of the present invention as described above, since the ink flow path 105 is formed parallel to the surface of the substrate 100 on the same plane as the ink chamber 106, it is possible to reduce the backflow of the ink. Since the ink chamber 106 and the ink flow path 105 are formed by the etching method, the shape of the ink chamber 106 and the ink flow path 105 may be variously modified. Therefore, the ink chamber 106 and the ink flow path 105 having the optimum shape can be formed. In addition, since the heat dissipation layer 128 made of metal may be formed to a relatively thick thickness by the plating process, effective heat dissipation may be achieved.

Hereinafter, a method of manufacturing an inkjet printhead according to an embodiment of the present invention will be described. 8 to 18 are cross-sectional views illustrating a process of manufacturing an inkjet printhead according to an embodiment of the present invention.

FIG. 8 illustrates a state in which oxide layers 130 and 140 are formed on the surface and the rear surface of the substrate 100 by oxidizing the substrate 100 after forming grooves on the surface of the substrate 100.

First, in the present embodiment, a silicon wafer is processed to a thickness of about 300 to 700 µm as the substrate 100. This is because silicon wafers are widely used in semiconductor devices and are effective for mass production.

On the other hand, as shown in Figure 8 shows a very small portion of the silicon wafer, the inkjet printhead according to the embodiment of the present invention can be manufactured in the state of tens to hundreds of chips on one wafer.

An etching mask defining a portion to be etched is formed on the prepared upper surface of the silicon substrate 100. The etching mask may be formed by applying a photoresist on a top surface of the substrate 100 to a predetermined thickness and then patterning the photoresist.

Subsequently, the substrate 100 exposed through the etching mask is etched to form a groove having a predetermined shape. The substrate 100 may be etched by a dry etching method such as reactive ion etching (RIE). The groove is a portion where an ink chamber (106 in FIG. 6) and an ink flow path (105 in FIG. 6) will be formed later, and the depth thereof is preferably about 10 to 80 mu m. Meanwhile, the groove may be formed in various shapes according to the etching form of the surface of the substrate 100, thereby obtaining an ink chamber and an ink passage having a desired shape. After the groove is formed, the etching mask on the substrate 100 is removed.

Subsequently, the grooves 100 on which the grooves are formed are oxidized to form silicon oxide layers 130 and 140 on the front and back surfaces of the substrate 100, respectively.

FIG. 9 illustrates a state in which a sacrificial layer 250 is formed in a groove formed in the substrate 100 and then the surface of the substrate 100 is planarized.

Specifically, the sacrificial layer 250 is formed by growing polysilicon in an epitaxial method in the groove formed on the surface of the oxidized substrate 100. Next, the surface of the sacrificial layer 250 and the substrate 100 is planarized to the same plane by chemical mechanical polishing (CMP). At this time, the silicon oxide layer 140 exposed to the outside is also removed.

FIG. 10 illustrates a first protective layer 121 formed on the entire surface of the resultant shown in FIG. 9, and a heater 108, a second protective layer 122, a conductor (112 of FIG. 5) and a third protective layer thereon. 126) is shown in a state of sequentially stacked.

Specifically, first, the first protective layer 121 is formed on the surface of the flattened substrate 100. The first protective layer 121 may be formed by depositing silicon oxide or silicon nitride.

Subsequently, a heater 108 is formed on the first protective layer 121. The heater 108 may be polysilicon, tantalum-aluminum alloy, tantalum nitride, titanium nitride, tungsten silicide, or the like doped with impurities on the entire surface of the first protective layer 121. It can be formed by depositing a heating resistor of a predetermined thickness and then patterning it. Specifically, the polysilicon may be deposited with a source gas of phosphorus (P) as an impurity to a thickness of about 0.7 to 1 μm by low pressure chemical vapor deposition (LPCVD), and a tantalum-aluminum alloy, Tantalum nitride, titanium nitride or tungsten silicide may be deposited to a thickness of approximately 0.1-0.3 μm by sputtering or chemical vapor deposition (CVD). The deposition thickness of the heat generating resistor can be set in another range so as to have an appropriate resistance value in consideration of the width and length of the heater 108. The heat generating resistor deposited on the entire surface of the first passivation layer 121 may be patterned by an etching process using a photomask and a photoresist and an etching process using a photoresist pattern as an etching mask.

Next, the second protective layer 122 made of silicon oxide or silicon nitride may be deposited to a thickness of about 0.2 μm to 1 μm on the entire surface of the first protective layer 121 on which the heater 108 is formed. Subsequently, the second protective layer 122 is etched to form a contact hole (not shown) that exposes the heater 108 in the portion to be connected to the conductor 112 (see FIG. 5).

Subsequently, a metal having good electrical and thermal conductivity, such as aluminum, an aluminum alloy, or gold or silver, is deposited on the entire surface of the second protective layer 122 to a thickness of about 0.5 to 2 μm by sputtering and patterned. 112 of FIG. 5 is formed. Then, the conductor 112 of FIG. 5 is connected to the heater 108 through the contact hole (not shown).

Next, a third protective layer 126 is formed on the upper surface of the second protective layer 122 and the conductor (112 in FIG. 5). Specifically, the third protective layer 126 is for insulation between the conductor (112 in FIG. 5) and the heat dissipation layer (128 in FIG. 6) to be formed later. The TEOS oxide may be formed by plasma chemical vapor deposition (PECVD); Plasma Enhanced Chemical Vapor Deposition) may be made by depositing a thickness of about 0.7 ~ 3㎛.

11 shows a state in which the lower nozzle 104a is formed. The lower nozzle 104a may be formed by sequentially etching the third protective layer 126, the second protective layer 122, and the first protective layer 121 by reactive ion etching (RIE). By the etching process, a part of the sacrificial layer 250 formed on the surface of the substrate 100 and both sides of the surface of the substrate 100 are exposed.

FIG. 12 illustrates a state in which a lower plating mold 350 is formed inside the lower nozzle 104a and the seed layer 127 is formed thereon. Specifically, the lower plating mold 350 may be formed by applying a photoresist on a resultant surface of FIG. 11 to a predetermined thickness and patterning the photoresist to leave only the photoresist filled in the lower nozzle 104a. Meanwhile, the lower plating mold 350 may be made of a photosensitive polymer as well as a photoresist.

Subsequently, a seed layer 127 for electroplating is formed on the entire surface of the resultant product. The seed layer 127 is formed by sputtering a metal such as copper (Cu), chromium (Cr), titanium (Ti), gold (Au), or nickel (Ni) having good conductivity for electroplating. It can be done by depositing at a thickness. The seed layer 127 may be formed of a plurality of metal layers.

FIG. 13 illustrates a state in which the upper plating mold 450 for forming the upper nozzle (104b of FIG. 6) is formed. The upper plating mold 450 may be formed by applying a photoresist to the entire surface of the seed layer 127 and then patterning the photoresist to leave the photoresist only at a portion where the upper nozzle (104b of FIG. 6) is to be formed. Meanwhile, the upper plating mold 450 may be made of a photosensitive polymer as well as a photoresist. The upper plating mold 450 is formed in a tapered shape whose diameter gradually decreases toward the upper side. On the other hand, the upper nozzle may be a columnar shape, in this case the upper plating mold is formed in a columnar shape.

Meanwhile, the lower plating mold 350 and the upper plating mold 450 may be formed through the following steps. Referring to FIG. 19, before forming the lower plating mold 350, a seed layer 127 ′ for electroplating is formed on the entire resultant surface of FIG. 11. Subsequently, the lower plating mold 350 and the upper plating mold 450 are sequentially formed. Meanwhile, the lower and upper plating molds 350 and 450 may be integrally formed together.

FIG. 14 illustrates a state in which a heat dissipation layer 128 made of a metal material having a predetermined thickness is formed on an upper surface of the seed layer 127. The heat dissipation layer 128 is approximately 10 to 100 μm by electroplating a metal having good thermal conductivity, such as nickel (Ni), copper (Cu), aluminum (Al), or gold (Au), on the seed layer 127 surface. It may be formed in a thickness. In this case, the heat dissipation layer 128 may be formed of a plurality of metal layers. The electroplating process is terminated at the point where the heat dissipation layer 128 is formed to a height that is lower than the height of the upper plating mold 450 and the exit cross-sectional area of the desired upper nozzle is formed. The thickness of the heat dissipation layer 128 is the cross-sectional area and cross-sectional shape of the upper nozzle. It may be appropriately determined in consideration of the substrate 100 and the heat radiation ability to the outside.

After the electroplating is completed, the surface of the heat dissipation layer 128 has irregularities due to the material layers formed thereunder. Therefore, the surface of the heat dissipation layer 128 can be planarized by chemical mechanical polishing (CMP).

Subsequently, the upper plating mold 450, the seed layer 127 under the upper plating mold 450, and the lower plating mold 350 are sequentially removed. The upper and lower plating molds 450 and 350 may be removed by a conventional photoresist removal method. The seed layer 127 uses an etchant capable of selectively etching only the seed layer 127 in consideration of the etching selectivity between the metal material constituting the heat dissipation layer 128 and the metal material constituting the seed layer 127. It can be etched by wet etching. For example, when the seed layer 127 is made of copper (Cu), it is possible to use an acetate-based etching solution, and when the seed layer 127 is made of titanium (Ti), an HF base etching solution may be used. Then, as shown in FIG. 15, the lower nozzle 104a and the upper nozzle 104b are connected to form a complete nozzle 104, and a nozzle plate 120 formed by stacking a plurality of material layers is completed. At this time, a part of the surface of the sacrificial layer 250 filled in the space for forming the ink chamber (106 in FIG. 6) and the ink flow path (105 in FIG. 6) is exposed through the nozzle 104.

FIG. 16 illustrates a state in which the manifold 102 is formed on the rear surface of the substrate 100. Specifically, an etching mask defining an area to be etched is formed by patterning the silicon oxide layer 130 formed on the back surface of the silicon substrate 100. Next, when the silicon substrate 100 exposed by the etching mask is wet etched using TMAH (Tetramethyl Ammonium Hydroxide) or potassium hydroxide (KOH) as an etchant, the side surface is hard as shown. Photo manifold 102 is formed. On the other hand, the manifold 102 may be formed by anisotropic dry etching the back surface of the substrate 100.

17 illustrates a state in which the ink chamber 106 and the ink flow path 105 are formed on the surface of the substrate 100. The ink chamber 106 and the ink flow passage 105 may be formed by isotropic etching of the sacrificial layer 250 of FIG. 16. Specifically, using the XeF ₂ gas or BrF ₃ gas as an etching gas, the sacrificial layer (250 of FIG. 16) exposed through the nozzle 104 is dry-etched for a predetermined time. In this case, since the etching of the sacrificial layer 250 of FIG. 16 is performed by isotropic etching, the sacrificial layer 250 of FIG. 16 is etched at the same speed in all directions from the portion exposed through the nozzle 104. However, further etching is prevented in the silicon oxide layer 140 serving as an etch stop. Accordingly, as shown, the ink chamber 106 and the ink flow path 105 are formed side by side on the surface of the substrate 100 on the same plane. Here, the depth of the ink chamber 106 and the ink flow path 105 formed on the surface of the substrate 100 is approximately 10 to 80 µm. The ink flow path 105 includes an ink channel 105a connected to the ink chamber 106, and an ink feed hole 105b connected to the manifold 102.

FIG. 18 illustrates a state in which the ink flow path 105 formed on the substrate 100 and the manifold 102 are connected. Specifically, when the silicon oxide layer 140 between the ink flow path 105 formed on the surface of the substrate 100 and the manifold 102 formed on the back surface of the substrate 100 is removed by a selective etching method, the ink flow path 105 and manifold 102 are connected. Thus, the inkjet printhead according to the embodiment of the present invention is completed.

20 to 22 are cross-sectional views showing another process of manufacturing the inkjet printhead according to the present invention. This manufacturing method is the same as the manufacturing method of the inkjet printhead described above except for forming the first sacrificial layer, and only a step of forming the first sacrificial layer will be described below.

First, as shown in FIG. 20, a silicon on insulator (SOI) substrate 300 having an insulating layer 320 interposed between two silicon substrates 310 and 330 is used as the substrate. Here, the thickness of the upper silicon substrate 330 is approximately 10 to 80 µm, and the thickness of the lower silicon substrate 310 is approximately 300 to 700 µm.

Next, as shown in FIG. 21, the surface of the upper silicon substrate 330 is etched to form a trench 340 having a predetermined shape to expose the insulating layer 320. The upper silicon substrate 330 may be etched by a dry etching method such as reactive ion etching (RIE). The trench 340 is formed in a shape surrounding a portion where an ink chamber (106 in FIG. 6) and an ink flow path (105 in FIG. 6) are to be formed, and the width of the trench 340 may be easily filled with a predetermined material therein. It is formed on the order of several micrometers.

Next, as shown in FIG. 22, the trench 340 is filled with silicon oxide 370, and then the surface of the upper silicon substrate 330 is planarized. Accordingly, the portion surrounded by the silicon oxide 370 becomes the sacrificial layer 250 ′ for forming the ink chamber (106 in FIG. 6) and the ink flow path (105 in FIG. 6). Therefore, the sacrificial layer 250 ′ formed by the manufacturing method is made of silicon, unlike the polysilicon described above.

Subsequent steps are the same as those shown in FIGS. 10 to 18 described above.

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, each element of the inkjet printhead according to the present invention may be a material different from the materials exemplified, and the method of laminating and forming each material is merely illustrative, and various deposition methods and etching methods may be applied. In addition, in the method of manufacturing an inkjet printhead according to the present invention, the order of each step may be different from that illustrated in some cases. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

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

First, by forming the ink flow path in parallel with the surface of the substrate on the same plane as the ink chamber, it is possible to prevent the poor discharge due to the backflow of the ink, thereby improving the performance of the printhead.

Second, since the heat dissipation layer can be formed to a thick thickness, it is possible to ensure the length of the nozzle long enough. Thereby, the flight straightness of the ink droplet discharged through a nozzle can be improved.

Third, effective heat dissipation may be achieved by dissipating heat remaining in the heater and its surroundings to the substrate and the outside through a heat dissipating layer made of a metal material. Thereby, the temperature rise of a nozzle site | part can be suppressed and as a result, a drive frequency can be improved.

Claims (26)

An ink chamber filled with the ink to be discharged is formed on the surface side thereof, a manifold for supplying ink to the ink chamber is formed on the rear side thereof, and an ink flow path connecting the ink chamber and the manifold is parallel to the surface thereof. A substrate formed; A plurality of protective layers stacked on the substrate and made of an insulating material, and a heat dissipating layer laminated on the protective layer by a plating process and made of a thermally conductive metal material, and a nozzle connected to the ink chamber is penetrated. Formed nozzle plate; And And a heater disposed between the protective layers of the nozzle plate and positioned above the ink chamber to heat the ink in the ink chamber, and a conductor to apply a current to the heater. Inkjet printheads. The method of claim 1, And the ink flow path is formed on the same plane as the ink chamber. The method of claim 1, And the ink flow path includes at least one ink channel connected to the ink chamber, and an ink feed hole connecting the ink channel and the manifold. The method of claim 1, The passivation layers include a first passivation layer, a second passivation layer, and a third passivation layer sequentially stacked on the substrate, and the heater is provided between the first passivation layer and the second passivation layer. The conductor is provided between the second protective layer and the third protective layer. The method of claim 1, The lower portion of the nozzle is formed in the plurality of protective layers, the inkjet printhead, characterized in that the upper portion of the nozzle is formed in the heat dissipating layer. The method of claim 5, wherein The upper portion of the nozzle formed in the heat dissipating layer is an inkjet printhead, characterized in that the tapered shape that the cross-sectional area is smaller toward the outlet. The method of claim 1, The heat dissipation layer is composed of at least one metal layer, each of the metal layer is an inkjet printhead, characterized in that made of any one metal material selected from the group consisting of nickel, copper, aluminum and gold. The method of claim 1, The heat dissipation layer is an inkjet printhead, characterized in that formed by a thickness of 10 ~ 100㎛. The method of claim 1, And a seed layer for electroplating the heat dissipating layer on the passivation layers. The method of claim 9, The seed layer is composed of at least one metal layer, each of the metal layer is an inkjet printhead, characterized in that made of any one metal material selected from the group consisting of copper, chromium, titanium, gold and nickel. Forming a sacrificial layer of a predetermined depth toward the surface of the substrate; Sequentially stacking a plurality of protective layers on the substrate on which the sacrificial layer is formed, forming a heater and a conductor connected to the heater between the protective layers; Forming a heat dissipation layer made of metal on the passivation layers, and forming a nozzle through which the ink is discharged to pass through the heat dissipation layer and the passivation layers to expose the sacrificial layer; Forming a manifold for supplying ink to the back side of the substrate; Removing the sacrificial layer exposed through the nozzle to form an ink chamber and an ink flow path; And Connecting the manifold and the ink flow path. The method of claim 11, Forming the sacrificial layer, Etching a surface of the substrate to form a groove having a predetermined depth; Oxidizing a surface of the substrate on which the groove is formed to form an oxide layer; And And filling a surface of the groove with a predetermined material, and then planarizing the surface of the substrate. The method of claim 12, Filling a predetermined material into the groove, epitaxially growing the polysilicon inside the groove is a manufacturing method of the inkjet printhead. The method of claim 11, Forming the sacrificial layer, Forming a trench of a predetermined shape in the upper silicon substrate of the SOI substrate; And And filling a predetermined material in the trench.  The method of claim 14, And the predetermined material is silicon oxide. The method of claim 11, Forming the protective layers, Forming a first passivation layer on a surface of the substrate on which the sacrificial layer is formed; Forming the heater on the first protective layer; Forming a second passivation layer on the first passivation layer and the heater; Forming the conductor on the second protective layer; And Forming a third passivation layer on the second passivation layer and the conductor. The method of claim 11, The heat dissipation layer is composed of at least one metal layer, each of the metal layer is a method of manufacturing an inkjet printhead, characterized in that formed by electroplating any one metal material selected from the group consisting of nickel, copper, aluminum and gold. . The method of claim 11, The heat dissipation layer is a manufacturing method of the inkjet printhead, characterized in that formed in a thickness of 10 ~ 100㎛. The method of claim 11, Forming the heat dissipation layer and the nozzle, Etching the passivation layers above the sacrificial layer to form a lower nozzle; Forming a lower plating mold in the lower nozzle; Forming an upper plating mold having a predetermined shape for forming an upper nozzle on the lower plating mold; Forming the heat dissipating layer on the passivation layers by electroplating; And And removing the upper and lower plating molds to form a nozzle including the upper nozzle and the lower nozzle. The method of claim 19, And the lower plating frame and the upper plating frame are made of photoresist or photosensitive polymer. The method of claim 11, Forming the heat dissipation layer and the nozzle, Etching the passivation layers above the sacrificial layer to form a lower nozzle; Forming a plating mold having a predetermined shape for forming an upper nozzle in a vertical direction from the inside of the lower nozzle; Forming the heat dissipating layer on the passivation layers by electroplating; And And removing the plating mold to form the nozzle comprising the upper nozzle and the lower nozzle. The method of claim 21, The plating mold is a method of manufacturing an inkjet printhead, characterized in that consisting of a photoresist or photosensitive polymer. The method of claim 19 or 21, The lower nozzle is formed by dry etching the protective layers by reactive ion etching. The method of claim 19 or 21, Forming a seed layer for electroplating the heat dissipating layer on the passivation layers. The method of claim 24, The seed layer is made of at least one metal layer, each metal layer is a method of manufacturing an inkjet printhead, characterized in that formed by depositing any one metal material selected from the group consisting of copper, chromium, titanium, gold and nickel. . The method of claim 19 or 21, And after the forming of the heat dissipating layer, planarizing the upper surface of the heat dissipating layer by a chemical mechanical polishing process.

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