KR20040036237A - Inkjet printhead with ink supplying mechanism through porous medium and method of manufacturing thereof - Google Patents

Abstract

PURPOSE: An ink jet print head and a method for feeding ink through a poly-hole medium are provided to efficiently control impedance of ink and to filter microscopic particles or impurities by feeding ink through the porous medium. CONSTITUTION: An ink jet print head having a structure for providing ink through a porous medium includes an ink chamber formed on a surface of a substrate(110) of the ink jet print head, and a manifold(136) formed on the rear side of the substrate(110). The manifold(136) allows ink to be fed onto an object from the ink chamber. The porous medium is used for the substrate(110). The porous medium includes a porous silicon substrate. Microscopic particles or impurities having a micro size are filtered through the porous medium.

Description

Inkjet printhead with ink supply structure through porous medium and manufacturing method thereof

The present invention relates to an inkjet printhead, and more particularly, to a thermally driven inkjet printhead having an ink supply structure through a porous medium and a method of manufacturing the same.

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. Accordingly, as the ink boils, bubbles are generated, and the generated bubbles expand and apply pressure to the ink filled in the ink chamber. 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, in order to increase dots per inch (DPI), it is necessary to be able to arrange a plurality 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. That is, the heated ink and the heater should be cooled quickly to increase the driving frequency.

On the other hand, impurity particles present in the ink cause a decrease in the performance of the printhead. In other words, when the impurity particles block the ink supply flow path, the ink may not be smoothly supplied into the ink chamber. These impurity particles may also be introduced during the assembly of the head chip and the ink cartridge, and even fine ink particles may still be present in the ink even though the ink passes through the filter of the cartridge. Therefore, in order to improve the performance of the printhead, in addition to the above requirements, impurities present in the ink must be filtered to prevent the impurity particles from blocking the ink supply flow path.

1 is a plan view of an inkjet printhead disclosed in US Pat. No. 5,734,399 as an example of a conventional inkjet printhead capable of filtering impurity particles.

Referring to FIG. 1, ink is supplied from the manifold 16 to the heater 12 site through the ink channel 14. In addition, various types of islands 18 using photoresists are disposed in the ink flow path to prevent the impurity particles 19 from entering the heater 12.

However, such an inkjet printhead has a limit in filtering fine impurity particles. Further, the above structure is applicable only when the ink channel is formed parallel to the surface of the substrate, and is difficult to apply when the ink channel is formed perpendicular to the surface of the substrate.

2 shows an inkjet printhead having an ink supply structure through a porous medium disclosed in US Pat. No. 5,940,099 as another example of a conventional inkjet printhead.

The inkjet printhead shown in FIG. 2 has a structure in which a drive layer 22, a cavity layer 24, an ink supply layer 26, and a nozzle layer 28 are laminated in order from top to bottom. have. A transducer 23, for example a piezoelectric body, is provided on the driving layer 22, and a cavity 25 in which ink is filled is formed in the cavity layer 24. A plurality of through holes 27 are formed in the ink supply layer 26 made of a porous medium, and a plurality of nozzles 29 for discharging ink are formed in the nozzle layer 28. On the other hand, the glass capillary in which the nozzle is formed at one end instead of the nozzle layer 28 may be fitted in the through hole 27 of the ink supply layer 26.

By the way, in order to manufacture an inkjet printhead having such a structure, the transducer 23 of the drive layer 22, the cavity 25 of the cavity layer 24, and the through hole 27 of the ink supply layer 26 are provided. ) And multiple layers 22, 24, 26, and 28 must be bonded while centering the nozzles 29 of the nozzle layer 28. Therefore, there is a disadvantage that the manufacturing process is complicated and a problem of misalignment may occur. In addition, since the ink flows into the cavity 25 from the ink reservoir through the side surface having a relatively small area compared to the upper and lower surfaces of the ink supply layer 26, the refilling speed of the ink is slow.

Meanwhile, FIG. 3 illustrates a monolithic inkjet printhead disclosed in the Korean patent application of the present applicant, which is disclosed as Korean Patent Application Publication No. 2002-007741 on January 29, 2002, as another example of a conventional inkjet printhead. have.

Referring to FIG. 3, a hemispherical ink chamber 32 is formed on the surface side of the silicon substrate 30, and a manifold 36 for ink supply is formed on the back side of the substrate 30. An ink channel 34 connecting the ink chamber 32 and the manifold 36 is formed through the bottom of the chamber 32. In addition, a nozzle plate 40 formed by stacking a plurality of material layers 41, 42, and 43 on the substrate 30 is integrally formed with the substrate 30. The nozzle plate 40 is formed in the nozzle plate 40 at a position corresponding to the center of the ink chamber 32, and a heater 45 connected to the conductor 46 is disposed around the nozzle 47. At the edge of the nozzle 47, a nozzle guide 44 extending in the depth direction of the ink chamber 32 is formed. The heat generated by the heater 45 is transferred to the ink 48 inside the ink chamber 32 through the insulating layer 41, whereby the ink 48 is boiled to generate bubbles 49. The resulting bubbles 49 expand and apply pressure to the ink 48 filled in the ink chamber 32, whereby the ink 48 is ejected through the nozzle 47 in the form of droplets 48 ′. Then, by the surface tension acting on the surface of the ink 48 in contact with the atmosphere, the ink 48 is sucked from the manifold 36 through the ink channel 34, and the ink is returned to the ink chamber 32 again. 48 is filled.

In the conventional integrated inkjet printhead having the structure as described above, the silicon substrate 30 and the nozzle plate 40 are integrally formed to simplify the manufacturing process and eliminate the problem of misalignment. 46, the ink chamber 32, the ink channel 34 and the manifold 36 are arranged vertically, there is an advantage that the nozzle density can be increased.

By the way, in the integrated inkjet printhead shown in FIG. 3, the ink channel 34 is formed by anisotropic ion etching of the substrate 30 at the bottom of the ink chamber 32 through the nozzle 47, so that the ink channel 34 ) Is constrained by the shape and cross-sectional area of the nozzle 47. Accordingly, there is a disadvantage that the flow impedance of the ink associated with the inflow of the ink 48 in the ejecting step of the ink droplets 48 'and the inflow of the ink in the refilling step of the ink cannot be actively controlled.

The present invention was created to solve the problems of the prior art as described above, and its object is to have an ink supply structure through a porous medium to effectively control the flow impedance of the ink and to filter fine impurity particles. An inkjet printhead is provided.

Another object of the present invention is to provide a method of manufacturing an inkjet printhead having the above structure without a bonding process or by minimizing a bonding process.

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

2 is a cross-sectional view showing another example of a conventional inkjet printhead.

3 is a cross-sectional view showing still another example of a conventional inkjet printhead.

Fig. 4 is a diagram showing the planar structure of the inkjet printhead according to the first preferred embodiment of the present invention.

FIG. 5 is a vertical sectional view of the inkjet printhead according to the first preferred embodiment of the present invention along the line AA ′ shown in FIG. 4.

6 is a graph illustrating the ink flow characteristics through a porous medium.

7 to 11 are vertical cross-sectional views showing second to sixth embodiments of the present invention.

12A to 12C are views for explaining a mechanism in which ink is supplied and discharged in the inkjet printhead according to the second embodiment of the present invention shown in FIG.

13 to 18 are cross-sectional views for explaining a method of manufacturing an inkjet printhead according to a first embodiment of the present invention shown in FIG. 5 step by step.

19 to 25 are cross-sectional views for explaining a method of manufacturing an inkjet printhead according to a second embodiment of the present invention shown in FIG.

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

110,510,610 ... substrate 511,611 ... first substrate

512,612 ... Second substrate 120,220,320 ... Nozzle plate

121 ... first protective layer 122 ... second protective layer

124 ... heat conducting layer 126 ... third protective layer

132,532,632 ... ink chamber 136,536,636 ... manifold

138,238,338 ... Nozzle 142 ... Heater

144 ... Conductor 129,229 ... Nozzle Guide

227 seed layer 228,328 heat dissipation layer

The present invention to achieve the above technical problem,

A substrate having an ink chamber filled with ink to be discharged on a surface thereof, and a manifold for supplying ink to the ink chamber at a predetermined distance from the ink chamber at a rear surface thereof;

A nozzle plate formed of a plurality of material layers stacked on the substrate, the nozzle plate penetrating through a nozzle through which ink is discharged from the ink chamber; And

And a heater provided between the material layers of the nozzle plate, the heater heating the ink inside the ink chamber, and a conductor applying a current to the heater.

The substrate provides an inkjet printhead wherein at least a lower portion of the ink chamber is made of a porous medium, through which ink is supplied from the manifold to the ink chamber through the porous medium.

Here, the substrate may be entirely made of a porous medium.

The substrate may include a first substrate on which the manifold is formed, a second substrate stacked on the first substrate, and the ink chamber is formed, and the first substrate may be formed of a porous medium.

The porous medium is preferably any one of a porous silicon substrate and a sintered metal plate.

The second substrate may be formed of a silicon substrate, a metal plate, or a metal layer plated on the first substrate.

The first substrate and the second substrate may be in close contact with each other, or may be joined with a predetermined gap by an adhesive.

Preferably, the ink chamber is formed to penetrate the second substrate so that an upper surface of the first substrate forms a bottom of the ink chamber.

The material layers of the nozzle plate are provided between the plurality of protective layers and the protective layers and are disposed above the ink chamber to be insulated from the heater and the conductor, and a portion thereof contacts the substrate. It is preferable to include.

In addition, the material layers of the nozzle plate preferably include a plurality of protective layers and a heat dissipation layer made of a metal stacked on the protective layers.

In addition, a nozzle guide extending into the ink chamber may be formed at a lower edge of the nozzle.

In addition, the present invention provides a method of manufacturing an inkjet printhead having the above structure.

The manufacturing method of the inkjet printhead according to the present invention,

Preparing a substrate made of a porous medium;

Forming a heater plate and a conductor connected to the heater between the material layers while forming a nozzle plate on the substrate, the nozzle plate comprising a plurality of stacked material layers and having nozzles penetrating the material layers;

Etching the substrate exposed through the nozzle to form an ink chamber filled with ink; And

And etching a rear surface of the substrate to form a manifold for supplying ink.

Here, the substrate is preferably one of a porous silicon substrate and a sintered metal plate.

And, the nozzle plate forming step,

Forming a plurality of passivation layers on the substrate sequentially, forming the heater and the conductor between the passivation layers, disposed above the ink chamber between the passivation layers, and insulated from the heater and the conductor; Forming a thermally conductive layer, a portion of which is in contact with the substrate; And etching through the protective layers to form the nozzle.

On the other hand, the nozzle plate forming step,

Forming a plurality of passivation layers on the substrate sequentially, forming the heater and the conductor between the passivation layers, disposed above the ink chamber between the passivation layers, and insulated from the heater and the conductor; Forming a thermally conductive layer, a portion of which is in contact with the substrate; Forming a heat dissipation layer made of a metal on the protective layers while penetrating the nozzles through the protective layers and the heat dissipation layer.

The forming of the heat dissipating layer and the nozzle may include:

Forming a lower nozzle by etching the passivation layers over the portion where the ink chamber is to be formed; Forming a first sacrificial layer inside the lower nozzle; Forming a second sacrificial layer for forming an upper nozzle on the first sacrificial layer; Forming said heat dissipating layer by electroplating for said protective layers; And removing the second sacrificial layer and the first sacrificial layer to form the nozzle including the lower nozzle and the upper nozzle.

In addition, after the step of forming the heat dissipating layer, the step of planarizing the upper surface of the heat dissipating layer by a chemical mechanical polishing process, it is preferable to further include.

Here, after forming a seed layer for electroplating the heat dissipation layer on the first sacrificial layer and the protective layers, the second sacrificial layer may be formed.

After forming the lower nozzle, a seed layer for electroplating the heat dissipation layer is formed on the protective layers and the substrate exposed by the lower nozzle, and then the first sacrificial layer and the second sacrificial layer. It may also form a layer.

And, forming the nozzle,

Anisotropically etching the protective layers and the substrate into the heater to form a hole having a predetermined depth, depositing a predetermined material layer on an inner surface of the hole, and etching the material layer formed at a bottom portion of the hole. And exposing the substrate and forming a nozzle guide formed of the material layer on the side of the hole and defining the nozzle.

The present invention also provides other methods of manufacturing an inkjet printhead having the above structure.

Another manufacturing method of the inkjet printhead according to the present invention,

Preparing a first substrate made of a porous medium;

Stacking a second substrate on the first substrate;

Forming a heater and a conductor connected to the heater between the material layers while forming a nozzle plate on the second substrate, the nozzle plate comprising a plurality of stacked material layers and having nozzles therethrough formed thereon;

Etching the second substrate exposed through the nozzle to form an ink chamber filled with ink; And

And forming a manifold for supplying ink to the rear side of the first substrate.

Here, the first substrate is preferably any one of a porous silicon substrate and a sintered metal plate, and the second substrate is preferably one of a silicon substrate and a metal plate.

The first substrate and the second substrate may be in close contact with each other, and in this case, the first substrate and the second substrate may be bonded by the SDB method.

On the other hand, the first substrate and the second substrate may be bonded with a predetermined gap by an adhesive.

Another manufacturing method of the inkjet printhead according to the present invention,

Preparing a first substrate made of a porous medium;

Forming an ink chamber in which ink is filled in the second substrate while stacking a second substrate made of metal on the first substrate;

Forming a heater and a conductor connected to the heater between the material layers while forming a nozzle plate on the second substrate, the nozzle plate comprising a plurality of stacked material layers and having nozzles therethrough formed thereon; And

And forming a manifold for supplying ink to the rear side of the first substrate.

Here, the first substrate is preferably any one of a porous silicon substrate and a sintered metal plate.

The stacking of the second substrate and forming the ink chamber may include:

Forming a sacrificial layer for forming the ink chamber on the first substrate, and forming the second substrate by electroplating a predetermined metal material on the first substrate. The sacrificial layer may be removed through the nozzle after the nozzle plate forming step.

Meanwhile, in the stacking of the second substrate and forming the ink chamber,

Forming the ink chamber through the second substrate made of a metal plate; bonding the second substrate on the first substrate; and filling a sacrificial layer in the ink chamber. The sacrificial layer may be removed through the nozzle after the nozzle plate forming step.

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.

4 is a view showing a planar structure of an inkjet printhead according to a first preferred embodiment of the present invention, and FIG. 5 is an inkjet according to a first preferred embodiment of the present invention along line AA ′ shown in FIG. Vertical cross section of the printhead.

4 and 5 together, an ink chamber 132 filled with ink to be discharged on a surface thereof is formed in the substrate 110 of the inkjet printhead to a predetermined depth, and an ink chamber 132 is formed on the rear surface thereof. A manifold 136 through which ink to be supplied flows is formed. The manifold 136 is formed below the ink chamber 132 and is connected to an ink reservoir (not shown) containing ink.

Meanwhile, although only the unit structure of the inkjet printhead is shown in the drawing, in the inkjet printhead manufactured in a chip state, a plurality of ink chambers 132 are arranged in a row or two rows on the manifold 136 to further increase the resolution. It may be arranged in three or more rows.

Here, a porous medium is used as the substrate 110. As the porous medium, a porous silicon substrate can be used, or a sintered metal plate such as sintered stainless plate or the like can be used. In the inkjet printhead according to the present invention, a separate ink channel connecting the ink chamber 132 and the manifold 136 is not formed. Therefore, the supply of ink to the ink chamber 132 is made through the substrate 110 made of a porous medium. To this end, the ink chamber 132 and the manifold 136 has a thickness of approximately several micrometers to several tens of micrometers, preferably 5 micrometers to 20 micrometers in consideration of the flow rate of the ink between the substrate 110 therebetween. It is formed to have. This will be described in detail later.

As described above, the nozzle plate 120 is provided on the porous substrate 110 on which the ink chamber 132 and the manifold 136 are formed. The nozzle plate 120 forms an upper wall of the ink chamber 132, and a nozzle 138 through which ink is discharged from the ink chamber 132 is vertically penetrated at a position corresponding to the center of the ink chamber 132. Is formed.

The cross-sectional shape of the nozzle 138 is preferably circular. On the other hand, the cross-sectional shape of the nozzle 138 may have a variety of shapes, such as elliptical or polygonal, not circular.

The nozzle plate 120 is formed of a plurality of material layers stacked on the substrate 110. The material layers include first and second protective layers 121 and 122, a thermal conductive layer 124, and a third protective layer 126. The heater 142 is provided between the first and second protective layers 121 and 122, and the conductor 144 is provided between the second protective layer 122 and the third protective layer 126.

The first passivation layer 121 is formed on the upper surface of the substrate 110 as a material layer at the bottom of the plurality of material layers constituting the nozzle plate 120. The first passivation layer 121 may be formed of silicon oxide or silicon nitride as a material layer for insulating and protecting the heater 142 between the heater 142 formed thereon and the substrate 110 thereunder.

On the first protective layer 121, a heater 142 positioned above the ink chamber 132 and heating the ink in the ink chamber 132 is formed in a shape surrounding the nozzle 138. The heater 142 is made of a resistive heating element such as polysilicon, a tantalum-aluminum alloy, tantalum nitride, titanium nitride, and tungsten silicide doped with impurities. The heater 142 may be formed in a circular ring shape surrounding the nozzle 138 as shown in FIG. 4, or may be formed in a square or diamond shape.

The second passivation layer 122 is provided on the first passivation layer 121 and the heater 142. The second protective layer 122 is provided for insulation between the thermal conductive layer 124 provided thereon and the heater 142 below and the protection of the heater 142. Like the first passivation layer 121, the second passivation layer 122 may be made of silicon nitride or silicon oxide.

A conductor 144 is provided on the second protective layer 122 to be electrically connected to the heater 142 to apply a pulse current to the heater 142. One end of the conductor 144 is connected to the heater 142 through the first contact hole C ₁ formed in the second protective layer 122, and the other end thereof is electrically connected to a bonding pad (not shown). In addition, the conductor 144 may be made of a metal having good conductivity, such as aluminum or an aluminum alloy, or gold or silver.

The thermal conductive layer 124 may be provided on the second protective layer 122. The thermal conductive layer 124 functions to conduct the heater 142 and the heat around the heater 142 to the substrate 110, and is wide enough to cover both the ink chamber 132 and the heater 142 as much as possible. It is preferably formed. However, in order to insulate between the heat conductive layer 124 and the conductor 144, the heat conductive layer 124 should be formed at a predetermined distance from the conductor 144. On the other hand, the insulation between the thermal conductive layer 124 and the heater 142 may be made by the second protective layer 122 interposed therebetween as described above. The thermal conductive layer 124 contacts the upper surface of the substrate 110 through the second contact hole C ₂ formed through the first protective layer 121 and the second protective layer 122.

The thermal conductive layer 124 is made of a metal having good thermal conductivity. As described above, when the thermal conductive layer 124 is formed on the second protective layer 122 together with the conductor 144, the thermal conductive layer 124 may be formed of a metal material such as the conductor 144, that is, aluminum or an aluminum alloy or the like. It can be made of gold or silver.

On the other hand, when the thermal conductive layer 124 is to be formed thicker than the thickness of the conductor 144, or to be formed of a metal material different from the conductor 144, not shown between the conductor 144 and the thermal conductive layer 124 An insulating layer may be further provided.

After the ink is discharged through the heat conductive layer 124, the heat remaining in the heater 142 and the surroundings may be more quickly conducted to the substrate 110. Therefore, since the heat dissipation is faster after the ink is discharged and the temperature around the nozzle 138 is lowered, stable printing is possible at a high driving frequency.

The third protective layer 126 is provided on the conductor 144 and the second protective layer 122. The third protective layer 126 may be made of tetraethylorthosilicate (TEOS) oxide or silicon oxide.

5, the nozzle guide 129 extending a predetermined length into the ink chamber 132 may be formed at the edge of the nozzle 138. As such, when the nozzle guide 129 is provided, the total length of the nozzle 138 becomes longer, and thus the straightness of the ink droplets discharged through the nozzle 138 may be further improved.

In the inkjet printhead according to the first embodiment of the present invention having the configuration as described above, the supply of ink to the ink chamber is made through a substrate made of a porous medium. Such supply of ink through the porous substrate suppresses back flow of ink in the ejection stage of the ink droplets, while conversely, ink flows smoothly into the ink chamber during the refilling stage of the ink. In addition, since the ink channel is not formed, the conventional problem of clogging the ink channel by impurity particles included in the ink can be fundamentally solved. In addition, there is an advantage that it is possible to fundamentally avoid the restrictions related to the shape and cross-sectional area of the ink channel generated in the structure having a conventional ink channel.

The flow characteristics of the ink through the porous medium will be described in more detail through the following equations and the graph and table 1 of FIG. 6.

The flow resistance of the ink through the porous medium can be expressed by Equation 1 below.

In Equation 1 above, K denotes a drag coefficient, u denotes a flow rate of ink, Re denotes Reynolds number, and A and B denote the porosity of the porous medium, the pore size, and the surface roughness of the pores. Represents a constant.

Herein, since the Reynolds number Re is represented by Equation 2 below, the flow resistance of the ink represented by Equation 1 may be represented by Equation 3 below.

In Equation 2, ρ represents the density of the ink, μ represents the viscosity of the ink, d represents the diameter of the average particle or fiber constituting the porous medium.

Looking at Equation 3, it can be seen that the flow resistance of the ink through the porous medium is proportional to the square of the velocity as well as the flow rate of the ink.

6 is a graph illustrating the ink flow characteristics through a porous medium. This graph shows the result of calculating the change of the flow resistance according to the flow velocity of the ink using the above equation (3). In this case, the porosity is assumed to be 0.9, d is 1㎛, ρ is 1,000kg / ㎡, μ is 2.3X10 ^-3 kg / ms.

In the graph of Figure 6, L line is the result of calculating the terms proportional to the flow rate of the ink in the equation (3), Q line is the result of calculating the terms proportional to the square of the velocity, T line is the result It is the sum result.

In a typical inkjet printhead, the flow rate of the ink in the ejecting step of the ink droplets by the expansion of the bubble is approximately 10 kPa, and the flow rate of the ink in the refilling step of the ink following the shrinkage of the bubble is approximately 0.1-1 kPa. Accordingly, it can be seen from the graph of FIG. 6 that the flow resistance to the reverse flow of ink at the time of ink droplet ejection is approximately 20 to 200 times compared to the flow resistance to the inflow of ink in the ink refilling step.

As described above, at the initial large velocity generated by the expansion of the bubble in the inkjet printhead according to the present invention, the flow resistance is increased relatively to effectively suppress the phenomenon of backflow of ink in the manifold direction, and In the refilling step of the ink which is followed by the shrinkage of the ink, the flow rate of the ink is small, so that the flow resistance is also reduced, so that the refilling of the ink is performed smoothly.

Table 1 below shows the numerical results of the ejection performance of the ink according to the properties of the porous medium.

Porosity, ε 0.9 0.9 0.8 Porous particle average diameter, d (μm) One 2 2 Bottom thickness of the ink chamber, t (μm) 5 10 5 Droplet discharge rate (m / s) 6.94 6.93 6.95 Volume of discharged droplets (pℓ) 12.45 12.20 12.70 Driving frequency 22.7 40.1 18.4

As shown in Table 1 above, selecting a porous medium having appropriate physical properties and appropriately adjusting the arrangement and size of the porous structure, the ink associated with the backflow phenomenon in the ink droplet ejection step and the ink inflow in the ink refill step It is possible to actively control the floating impedance of, resulting in a printhead having the desired discharge performance.

7 to 11 are vertical cross-sectional views showing second to sixth embodiments of the present invention. Here, the same reference numerals as the reference numerals shown in FIG. 5 indicate the same components.

Referring to FIG. 7, the inkjet printhead according to the second embodiment of the present invention has a structure further including a heat dissipation layer 228 made of metal in the basic structure shown in FIG. 5. That is, the nozzle plate 220 formed on the porous substrate 110 is formed of the first and second protective layers 121 and 122, the thermal conductive layer 124, the third protective layer 126, and the metal. And a heat dissipation layer 228.

The first, second, and third protective layers 121, 122, and 126, the thermal conductive layer 124, and the heater 142 and the conductor 144 provided therebetween are the same as in the first embodiment described above. Therefore, the description is omitted. However, it is preferable that the third protective layer 126 is not formed as much as possible on the upper surface of the heat conductive layer 124 for contact with the heat dissipating layer 228 which will be described later.

The heat dissipation layer 228 is a top material layer of the plurality of material layers constituting the nozzle plate 220. The heat dissipation layer 228 is a metal material having good thermal conductivity, such as Made of metals such as nickel, copper or gold. The heat dissipation layer 228 is formed to a relatively thick thickness of about 10 to 100 μm by electroplating the metal material on the third protective layer 126 and the heat conductive layer 124. To this end, a seed layer 227 for electroplating the metal material is provided on the third protective layer 126 and the thermal conductive layer 124. The seed layer 227 may be made of a metal having good electrical conductivity such as copper, chromium, titanium, gold, or nickel.

As such, since the heat dissipation layer 228 made of metal is formed by a plating process, the heat dissipation layer 228 may be formed integrally with other components of the inkjet printhead, and may also be formed with a relatively thick thickness, so that effective heat dissipation may be achieved. have.

The heat dissipation layer 228 functions to dissipate heat to the outside of the heater 142 and the surroundings thereof. That is, after the ink is discharged, the heat remaining in the heater 142 and its surroundings is conducted to the substrate 110 and the heat dissipating layer 228 through the heat conductive layer 124 and is emitted to the outside. Therefore, since the heat dissipation is faster after the ink is discharged and the temperature around the nozzle 238 is lowered, stable printing is possible at a high driving frequency.

A lower portion 238a of the nozzle 238 is formed in a columnar shape in the first, second, and third protective layers 121, 122, and 126 of the nozzle plate 220. The upper portion 238b of the nozzle 238 is formed in the heat dissipating layer 228, and the upper nozzle 238b has a tapered shape in which the cross-sectional area decreases toward the outlet side.

As described above, when the shape of the upper nozzle 238b is tapered, there is an advantage that the meniscus on the surface of the ink is stabilized more quickly after the ejection of the ink.

The inkjet printhead according to the third embodiment of the present invention shown in FIG. 8 has a structure further including a nozzle guide 229 in the structure shown in FIG. Specifically, a nozzle guide 229 extending a predetermined length into the ink chamber 132 is formed at the edge of the lower nozzle 238a. Therefore, the length of the lower nozzle 238a is longer by the nozzle guide 229, so that the straightness of the ink droplets discharged through the nozzle guide 229 can be further improved.

The inkjet printhead according to the fourth embodiment of the present invention shown in FIG. 9 has a structure in which the shape of the upper nozzle 338b is changed from tapered to columnar in the structure shown in FIG. Specifically, the nozzle 338 formed on the nozzle plate 320 includes a columnar lower nozzle 338a formed on the first, second and third protective layers 121, 122, and 126, and the heat dissipation layer 328. It consists of a columnar upper nozzle (338b) formed in the). In addition, a nozzle guide may be provided in the lower nozzle 338a of the printhead illustrated in FIG. 9 as illustrated in FIG. 8.

The inkjet printhead according to the fifth embodiment of the present invention shown in FIG. 10 has the same nozzle plate 220 as shown in FIG. However, the substrate 510 under the nozzle plate 220 has a structure in which the first substrate 511 on which the manifold 536 is formed and the second substrate 512 on which the ink chamber 532 is formed are stacked. Here, the first substrate 511 is made of a porous medium, such as a porous silicon substrate or a sintered metal plate, as in the above embodiments so that ink can pass therethrough. On the other hand, the second substrate 512 may be formed of a silicon substrate or a metal plate, which is not porous. The ink chamber 532 is formed to penetrate the second substrate 512, so that the first substrate 511 forms the bottom of the ink chamber 532. Therefore, ink may be supplied into the ink chamber 532 through the first substrate 511 made of a porous medium. In addition, the ink chamber 532 may be formed in a columnar shape instead of a hemispherical shape. The first substrate 511 and the second substrate 512 may be bonded by a well-known silicon direct bonding (SDB) method so that a gap does not exist between them.

Meanwhile, the inkjet printhead according to the sixth embodiment of the present invention shown in FIG. 11 is similar to the structure shown in FIG. 10, but includes a first substrate 611 constituting a substrate 610 supporting the nozzle plate 220. ) And the second substrate 612 differ in that they are stacked with a predetermined gap G. As described above, the first substrate 611 is made of a porous medium, and a manifold 636 is formed at a bottom thereof. The second substrate 612 is formed of a silicon substrate or a metal plate, which is not porous, and is formed through the ink chamber 632. In addition, the ink chamber 632 may be formed in a columnar shape instead of a hemispherical shape. The first and second substrates 611 and 612 are bonded to each other with a predetermined gap G by an adhesive 613, and a plurality of adhesives 613 are intermittently interposed around the ink chamber 632. Is placed. Accordingly, ink may be supplied into the ink chamber 632 not only through the first substrate 611 but also through the gap G between the first substrate 611 and the second substrate 612. Thus, the refilling speed of the ink can be faster.

Hereinafter, referring to FIGS. 12A to 12C, a mechanism of discharging ink from an inkjet printhead according to the present invention will be described. The ink ejection mechanism is described below with reference to the inkjet printhead according to the second embodiment shown in FIG.

First, referring to FIG. 12A, when the ink 150 is filled in the ink chamber 132 and the nozzle 238, a current in the form of a pulse is applied to the heater 142 through the conductor 144. Heat is generated. The generated heat is transferred to the ink 150 inside the ink chamber 132 through the first protective layer 121 under the heater 142, whereby the ink 150 is boiled to generate bubbles 160. . The generated bubble 160 expands with a continuous supply of heat, so that ink 150 inside the nozzle 238 is pushed out of the nozzle 238. At this time, the high pressure by the expansion of the bubble 160 generates a high-speed ink flow to flow back the ink 150 not only toward the nozzle 238 but also toward the manifold 136, as described above, the porous substrate 110 This backflow phenomenon is suppressed due to the large flow resistance in.

Subsequently, referring to FIG. 12B, when the current applied at the time when the bubble 160 is inflated is blocked, the bubble 160 contracts and disappears. At this time, negative pressure is applied to the ink chamber 132 so that the ink 150 inside the nozzle 238 is returned to the ink chamber 132 again. At the same time, the portion pushed out of the nozzle 238 is separated from the ink 150 inside the nozzle 238 by the inertia force and is discharged.

After the ink droplets 150 'are separated, the meniscus on the surface of the ink 150 formed inside the nozzle 238 is retracted toward the ink chamber 132. At this time, in the present invention, since the nozzle 238 sufficiently long is formed by the thick nozzle plate 220, the meniscus retreats only in the nozzle 238 and does not retreat into the ink chamber 132. . Therefore, outside air is prevented from entering into the ink chamber 132, and the return to the initial state of the meniscus is also accelerated, so that high-speed discharge of the ink droplet 150 ′ can be stably maintained. Then, with the contraction of the bubble 160, the flow of ink from the manifold 136 toward the ink chamber 132 is started through the porous substrate 110, and at this time, the porous substrate 110 becomes a relatively low-speed flow. The flow resistance in) also becomes small, so that the inflow of ink is smooth. In this process, after the ink droplets 150 'are discharged, the heat remaining in the heater 142 and the periphery thereof is conducted through the heat conducting layer 124 and the heat dissipating layer 228 to dissipate to the substrate 110 or to the outside. Therefore, the temperature of the heater 142 and the nozzle 238 and the surroundings are lowered more quickly.

Next, referring to FIG. 12C, when the negative pressure inside the ink chamber 132 disappears, the ink 150 may again be discharged by the surface tension acting on the meniscus formed in the nozzle 238. It rises toward the outlet end. At this time, when the upper portion 238a of the nozzle 238 has a tapered shape, there is an advantage that the rising speed of the ink 150 becomes faster. Accordingly, the inside of the ink chamber 132 is filled again with the ink 150 supplied through the porous substrate 110. In this case, since the relatively low-speed flow is maintained as described above, the flow resistance in the porous substrate 110 is small, so that the ink 150 may be refilled quickly. When the refilling of the ink 150 is completed and returned to the initial state, the above process is repeated. In this process, heat dissipation is performed through the heat conduction layer 124 and the heat dissipation layer 228, and thermally, the return to the initial state can be made faster.

Hereinafter, a preferred manufacturing method of the inkjet printhead according to the present invention having the structure as described above will be described.

13 to 18 are cross-sectional views for explaining a method of manufacturing an inkjet printhead according to a first embodiment of the present invention shown in FIG. 5 step by step.

First, referring to FIG. 13, in the present embodiment, the substrate 110 is used by processing a porous medium such as a porous silicon substrate to a thickness of about 300 to 500 μm.

On the other hand, as shown in Figure 13 shows a very small portion of the silicon wafer, the inkjet printhead according to the present invention can be manufactured in a state of tens to hundreds of chips on one wafer.

Then, the first protective layer 121 is formed on the prepared upper surface of the porous substrate 110. The first protective layer 121 may be formed by depositing silicon oxide or silicon nitride on the upper surface of the substrate 110.

Subsequently, the heater 142 is formed on the first protective layer 121 formed on the upper surface of the substrate 110. The heater 142 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 resistance heating element of a predetermined thickness and then patterning it. Specifically, polysilicon may be deposited to a thickness of about 0.7 to 1 μm by low pressure chemical vapor deposition (LPCVD) with a source gas of phosphorus (P) as an impurity, for example, a tantalum-aluminum alloy, Tantalum nitride, titanium nitride, or tungsten silicide may be deposited to a thickness of about 0.1 μm to about 0.3 μm by sputtering, chemical vapor deposition (CVD), or the like. The deposition thickness of the resistance heating element may be set in another range so as to have an appropriate resistance value in consideration of the width and length of the heater 142. The resistive heating element deposited on the entire surface of the first protective layer 121 may be patterned by an etching process of etching using a photomask and a photoresist pattern as an etching mask.

Next, as shown in FIG. 14, the second protective layer 122 is formed on the upper surfaces of the first protective layer 121 and the heater 142. Specifically, the second protective layer 122 may be formed by depositing silicon oxide or silicon nitride to a thickness of about 0.5 to 3 μm. Subsequently, the second protective layer 122 is partially etched to form a first contact hole C ₁ exposing a part of the heater 142, that is, a part to be connected to the conductor 144 in the step of FIG. 15, The second contact hole exposing the second protective layer 122 and the first protective layer 121 sequentially to expose a portion of the substrate 110, that is, a portion to be in contact with the thermal conductive layer 124 in the step of FIG. 15. C ₂ ). The first and second contact holes C ₁ and C ₂ may be simultaneously formed.

FIG. 15 illustrates a state in which the conductor 144 and the thermal conductive layer 124 are formed on the upper surface of the second protective layer 122. Specifically, the conductor 144 and the thermal conductive layer 124 may be formed simultaneously by depositing and patterning a metal having good electrical and thermal conductivity, such as aluminum or an aluminum alloy, or gold or silver, by sputtering to a thickness of about 1 μm. . At this time, the conductor 144 and the thermal conductive layer 124 are formed to be insulated from each other. Then, the conductor 144 is connected to the heater 142 through the first contact hole C ₁ , and the thermal conductive layer 124 is in contact with the substrate 110 through the second contact hole C ₂ .

On the other hand, when the thickness of the heat conductive layer 124 is to be thicker than the thickness of the conductor 144 or the metal material forming the heat conductive layer 124 is to be a different metal from the conductor 144, or the conductor 144 and the heat conductive layer In the case where the 124 is to be insulated more reliably, the conductor 144 can be formed first, and then the heat conductive layer 124 can be formed. In more detail, in the step of FIG. 14, only the first contact hole C ₁ is formed to form only the conductor 144, and then an insulating layer (not shown) is formed on the conductor 144 and the second protective layer 122. To form. The insulating layer may also be formed of the same material as the second protective layer 122 by the same method. Subsequently, the insulating layer and the second and first protective layers 122 and 121 are sequentially etched to form a second contact hole C ₂ . Then, the thermal conductive layer 124 is formed by the same method as described above. Then, an insulating layer is interposed between the conductor 144 and the heat conductive layer 124.

Subsequently, as illustrated in FIG. 16, the second protective layer 122 and the first protective layer 121 may be reactive ion etching (RIE) in a cross-sectional shape without departing from the inner boundary of the heater 142. Anisotropic etching is performed, and then the substrate 110 is anisotropically etched in the same manner to form holes 129 'having a predetermined depth.

Next, as shown in FIG. 17, a third protective layer 126 is formed on the entire surface of the resultant product of FIG. 16. The third protective layer 126 may be formed by, for example, depositing TEOS oxide to a thickness of about 0.7 to 3 μm by plasma chemical vapor deposition (PECVD). At this time, the TEOS oxide deposited on the inner surface of the hole 129 'forms the nozzle guide 129. Subsequently, the third protective layer 126 at the bottom of the hole 129 'is etched to expose the substrate 110.

The hole 129 ′ may be formed after the third protective layer 126 is formed. In this case, another material layer is deposited on the inner surface of the hole 129 ′ and the third protective layer 126 to form the nozzle guide 129.

In addition, when the nozzle guide 129 is not formed, the third protective layer 126 is formed after the step of FIG. 15. Subsequently, the third, second and first protective layers 126, 122, and 121 are sequentially etched to form the nozzle 138, and then the steps shown in FIG. 18 are performed.

FIG. 18 illustrates a state in which an ink chamber 132 having a predetermined depth is formed on the surface side of the substrate 110, and a manifold 136 is formed on the back side of the substrate 110. The ink chamber 132 may be formed by isotropic etching of the porous substrate 110 exposed by the nozzle 138. Specifically, the substrate 110 is dry-etched for a predetermined time using XeF ₂ gas or BrF ₃ gas as an etching gas. Then, as shown, an ink chamber 132 having a predetermined depth and radius is formed. The back surface of the porous substrate 110 is etched to form the manifold 136. Specifically, after forming an etching mask defining a region to be etched on the back of the substrate 110, using a tetramethyl Ammonium Hydroxide (TMAH) or potassium hydroxide (KOH) as an etching solution on the back of the substrate 110 When wet etched, a side sloping manifold 136 is formed as shown. Meanwhile, the manifold 136 may be formed by anisotropic dry etching the back surface of the substrate 110.

After the above steps, the inkjet printhead according to the first embodiment of the present invention implemented on the porous substrate 110 is completed as shown in FIG. 18.

19 to 25 are cross-sectional views for explaining a method of manufacturing an inkjet printhead according to a second embodiment of the present invention shown in FIG. In addition, since the manufacturing method of the inkjet printhead according to the third and fourth embodiments of the present invention shown in FIGS. 8 and 9 is similar to the manufacturing method described below, only the differences will be briefly described.

First, after passing through the steps illustrated in FIGS. 13 to 15, a third protective layer 126 is formed on the entire surface of the resultant product of FIG. 15, as shown in FIG. 19. Next, the third protective layer 126 is partially etched to expose the thermal conductive layer 124.

20 illustrates a state in which the lower nozzle 238a is formed. The lower nozzle 238a reacts the third protective layer 126, the second protective layer 122, and the first protective layer 121 inside the heater 142 to have a cross-sectional shape without departing from the inner boundary of the heater 142. It may be formed by sequentially etching by reactive ion etching (RIE).

Meanwhile, when the lower nozzle 238a is formed, the nozzle guide 229 shown in FIG. 8 may be formed as in the aforementioned manufacturing method.

Next, as shown in FIG. 21, the first sacrificial layer PR ₁ is formed in the lower nozzle 238a. Specifically, after the photoresist is applied to the entire surface of the resultant of FIG. 20, the photoresist is patterned to leave only the photoresist filled inside the lower nozzle 238a. The remaining photoresist forms the first sacrificial layer PR ₁ and maintains the shape of the lower nozzle 238a in a subsequent process. Subsequently, a seed layer 227 for electroplating is formed on the entire surface of the resultant product. The seed layer 227 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. Meanwhile, the seed layer 227 may be formed of a plurality of metal layers, in which case each of the plurality of metal layers is copper (Cu), chromium (Cr), titanium (Ti), gold (Au), nickel (Ni), or the like. It can be formed by depositing a metal of.

FIG. 22 illustrates a state in which the second sacrificial layer PR ₂ for forming the upper nozzle is formed. Specifically, the photoresist is applied to the entire surface of the seed layer 227 and then patterned so that the photoresist remains only at the portion where the upper nozzle 238b of FIG. 24 is to be formed. The remaining photoresist is formed in a tapered shape whose diameter gradually decreases upwards to serve as the second sacrificial layer PR ₂ for forming the upper nozzle 238b in a subsequent process.

Meanwhile, when the upper nozzle 338b having the columnar shape illustrated in FIG. 9 is to be formed, the second sacrificial layer PR ₂ is formed in the columnar shape.

And. The first sacrificial layer PR ₁ and the second sacrificial layer PR ₂ may be formed of a photosensitive polymer as well as a photoresist.

Next, as shown in FIG. 23, a heat dissipation layer 228 made of a metal material having a predetermined thickness is formed on the seed layer 227. The heat dissipation layer 228 may be formed to a thickness of about 10 to 100 μm by electroplating a metal having good thermal conductivity, such as nickel (Ni), copper (Cu), or gold (Au), on the seed layer 227. . The electroplating process is terminated when the heat dissipation layer 228 is formed to a height lower than the height of the second sacrificial layer PR ₂ and the exit cross section of the desired upper nozzle 238b is formed. The thickness of the heat dissipation layer 228 may be appropriately determined in consideration of the cross-sectional area and the cross-sectional shape of the upper nozzle 238b, the heat dissipation ability to the substrate 110 and the outside.

After the electroplating is completed, the surface of the heat dissipation layer 228 has irregularities by the material layers formed thereunder. Accordingly, the surface of the heat dissipation layer 228 may be planarized by chemical mechanical polishing (CMP).

Subsequently, the second sacrificial layer PR ₂ for forming the upper nozzle, the seed layer 227 under the second sacrificial layer PR ₂ , and the first sacrificial layer PR ₁ for holding the lower nozzle are sequentially etched. . Then, as shown in FIG. 24, the lower nozzle 238a and the upper nozzle 238b are connected to form a complete nozzle 238, and a nozzle plate 220 formed by stacking a plurality of material layers is completed.

On the other hand, the nozzle 238 and the heat dissipation layer 228 may be formed through the following steps. In the step of FIG. 21, before forming the first sacrificial layer PR ₁ for maintaining the lower nozzle 238a, the seed layer 227 for electroplating is formed on the entire surface of the resultant product of FIG. 20. Subsequently, the second sacrificial layer PR ₂ for forming the first sacrificial layer PR ₁ and the upper nozzle 238b is sequentially formed or integrally formed together. Next, after forming the heat dissipation layer 228 as shown in FIG. 23, the surface of the heat dissipation layer 228 is planarized by chemical mechanical polishing. Subsequently, when the second sacrificial layer PR ₂ , the first sacrificial layer PR ₁ , and the seed layer 227 under the first sacrificial layer PR ₁ are etched together, the nozzle ( 238 and the nozzle plate 220 may be formed.

FIG. 25 illustrates a state in which an ink chamber 132 having a predetermined depth is formed on the surface side of the substrate 110, and a manifold 136 is formed on the back side of the substrate 110. Since the formation method of the ink chamber 132 and the manifold 136 is the same as that of the manufacturing method mentioned above, the description is abbreviate | omitted.

After the above steps, the inkjet printhead according to the second embodiment of the present invention implemented on the porous substrate 110 is completed as shown in FIG. 25.

The inkjet printhead according to the fifth embodiment of the present invention shown in FIG. 10 can also be manufactured by a method similar to the above manufacturing method. However, after the second substrate 512 is laminated and bonded on the first substrate 511, the above-described steps are performed. At this time, when the first substrate 511 is made of a porous silicon substrate and the second substrate 512 is made of a silicon substrate, the first substrate 511 and the second substrate 512 are as described above. It can be bonded by the well-known Silicon Direct Bonding (SDB) method so that there is no gap between them. In addition, in the forming of the ink chamber 532 by etching the second substrate 512, the thickness of the second substrate 512 is determined so that the first substrate 511 may be exposed on the bottom of the ink chamber 532. shall.

As described above, the second substrate 512 may be formed of a metal layer. In this case, the second substrate 512 may be formed by plating a metal material to a predetermined thickness on the first substrate 511. . In addition, in the case of forming the ink chamber 532 in the form of a column, as in the method of forming the upper nozzle in the heat dissipating layer, after forming the sacrificial layer in the form of a column in the region where the ink chamber 532 is to be formed, the metal Plate the material. The sacrificial layer is removed through the nozzle 238 after forming the nozzle plate 220.

In the inkjet printhead according to the sixth embodiment of the present invention shown in FIG. 11, the second substrate 612 is bonded onto the first substrate 611 by an adhesive 613 with a predetermined gap G therebetween. It can be prepared by performing the above steps. At this time, when the second substrate 612 is made of a silicon substrate, after forming the nozzle plate 220, the second substrate 612 is etched through the nozzle 238 to form the ink chamber 632. At this time, the thickness of the second substrate 612 should be determined so that the first substrate 611 is exposed at the bottom of the ink chamber 632.

On the other hand, the second substrate 612 may be made of a metal plate as described above, in this case, after forming the ink chamber 632 on the second substrate 612 by etching or the like in advance, and then to the ink chamber 632 Filling the sacrificial material and forming the nozzle plate 220 may be performed. The sacrificial material is removed through the nozzle 238 after forming the nozzle plate 220.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and equivalent other embodiments are possible. For example, the materials used to construct each element of the printhead in the present invention may use materials not illustrated. In addition, as a method of laminating and forming each material is merely illustrated, various deposition methods and etching methods may be applied. In addition, the specific values exemplified in each step may be adjusted outside the exemplified ranges as long as the manufactured printhead can operate normally. In addition, the order of each step of the printhead manufacturing method of the present invention 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 inkjet printhead and its manufacturing method according to the present invention have the following effects.

First, by having the ink supply structure through the porous medium, the flow resistance increases relatively at the initial large speed caused by the expansion of the bubble, so that the backflow of the ink can be effectively suppressed, and with the shrinkage of the bubble In the subsequent refilling of the ink, the flow velocity of the ink is small so that the flow resistance is also small, so that the ink refilling is performed smoothly.

Second, by selecting a porous medium having appropriate physical properties and appropriately adjusting the placement and size of the porous structure, it is possible to actively control the flow impedance of the ink associated with the backflow phenomenon in the ink droplet ejecting step and the ink inflow in the ink refilling step. As a result, it is possible to realize a printhead having a desired ejection performance.

Third, since the ink channel is not formed, the conventional problem of clogging the ink channel by impurity particles contained in the ink can be fundamentally solved, and the constraints related to the shape and cross-sectional area of the ink channel generated in the structure having the conventional ink channel can be solved. And fundamentally avoid.

Fourth, by forming a thick heat dissipating layer made of a metal on the nozzle plate, the heat dissipation ability is improved to improve the ink discharge performance and the driving frequency.

Fifth, since the bonding process is unnecessary or minimized, the manufacturing process can be simplified and the problem of misalignment can be minimized.

Claims (38)

A substrate having an ink chamber filled with ink to be discharged on a surface thereof, and a manifold for supplying ink to the ink chamber at a predetermined distance from the ink chamber at a rear surface thereof; A nozzle plate formed of a plurality of material layers stacked on the substrate, the nozzle plate penetrating through a nozzle through which ink is discharged from the ink chamber; And And a heater provided between the material layers of the nozzle plate, the heater heating the ink inside the ink chamber, and a conductor applying a current to the heater. And the substrate is formed of at least a lower portion of the ink chamber from a porous medium, and ink is supplied from the manifold to the ink chamber through the porous medium. The method of claim 1, And the substrate is entirely made of a porous medium. The method of claim 1, And the substrate comprises a first substrate on which the manifold is formed, a second substrate stacked on the first substrate, and on which the ink chamber is formed, wherein the first substrate is made of a porous medium. The method of claim 2 or 3, And the porous medium is one of a porous silicon substrate and a sintered metal plate. The method of claim 3, And the second substrate is one of a silicon substrate and a metal plate. The method of claim 3, And the second substrate is formed of a metal layer plated on the first substrate. The method of claim 3, The inkjet printhead of claim 1, wherein the first substrate and the second substrate are in close contact with each other. The method of claim 3, And the first substrate and the second substrate are bonded to each other with a predetermined gap by an adhesive. The method of claim 3, And the ink chamber is formed to pass through the second substrate so that an upper surface of the first substrate forms a bottom of the ink chamber. The method of claim 1, The material layers of the nozzle plate include a plurality of protective layers and a thermally conductive layer disposed between the protective layers and disposed above the ink chamber and insulated from the heater and the conductor, a portion of which is in contact with the substrate. An inkjet printhead, characterized in that. The method of claim 10, The thermal conductive layer is an inkjet printhead, characterized in that made of any one metal of aluminum, aluminum alloy, gold and silver. The method of claim 1, And the material layers of the nozzle plate include a plurality of passivation layers and a heat dissipation layer formed on the passivation layers and made of a metal. The method of claim 12, The heat dissipating layer is an inkjet printhead, characterized in that made of any one metal of nickel, copper and gold. The method of claim 1, And a nozzle guide extending into the ink chamber at a lower edge of the nozzle. Preparing a substrate made of a porous medium; Forming a heater plate and a conductor connected to the heater between the material layers while forming a nozzle plate on the substrate, the nozzle plate comprising a plurality of stacked material layers and having nozzles penetrating the material layers; Etching the substrate exposed through the nozzle to form an ink chamber filled with ink; And And forming a manifold for supplying ink by etching the rear surface of the substrate. The method of claim 15, The substrate is a method of manufacturing an inkjet printhead, characterized in that any one of a porous silicon substrate and a sintered metal plate. The method of claim 15, wherein forming the nozzle plate, Forming a plurality of passivation layers on the substrate sequentially, forming the heater and the conductor between the passivation layers, disposed above the ink chamber between the passivation layers, and insulated from the heater and the conductor; Forming a thermally conductive layer, a portion of which is in contact with the substrate; And And forming the nozzle by etching the protective layers so as to penetrate through the passivation layers. The method of claim 15, wherein forming the nozzle plate, Forming a plurality of passivation layers on the substrate sequentially, forming the heater and the conductor between the passivation layers, disposed above the ink chamber between the passivation layers, and insulated from the heater and the conductor; Forming a thermally conductive layer, a portion of which is in contact with the substrate; And And forming the nozzle through the protective layers and the heat dissipating layer while forming a heat dissipating layer made of a metal on the protective layers. The method of claim 18, The heat dissipating layer is a method of manufacturing an inkjet printhead, characterized in that made of any one metal of nickel, copper and gold. The method of claim 18, wherein the forming of the heat dissipation layer and the nozzle comprises: Forming a lower nozzle by etching the passivation layers on an upper portion of the portion where the ink chamber is to be formed; Forming a first sacrificial layer inside the lower nozzle; Forming a second sacrificial layer for forming an upper nozzle on the first sacrificial layer; Forming the heat dissipating layer by electroplating for the protective layers; And And removing the second sacrificial layer and the first sacrificial layer to form the nozzle including the lower nozzle and the upper nozzle. The method of claim 20, And after the forming of the heat dissipating layer, planarizing an upper surface of the heat dissipating layer by a chemical mechanical polishing process. The method of claim 20, And forming a second sacrificial layer after forming a seed layer for electroplating the heat dissipating layer on the first sacrificial layer and the passivation layers. The method of claim 20, After forming the lower nozzle, a seed layer for electroplating the heat dissipation layer is formed on the protective layers and the substrate exposed by the lower nozzle, and then the first sacrificial layer and the second sacrificial layer are formed. Forming an inkjet printhead, characterized in that the forming. The method of claim 22 or 23, And the first and second sacrificial layers are made of any one of a photoresist and a photosensitive polymer. The method of claim 22 or 23, And the seed layer is formed by depositing any one metal among copper, chromium, titanium, gold and nickel. The method of claim 17 or 18, wherein forming the nozzle, Anisotropically etching the protective layers and the substrate into the heater to form a hole having a predetermined depth; Depositing a layer of material on an inner surface of the hole; And etching the material layer formed at the bottom of the hole to expose the substrate, and simultaneously forming a nozzle guide on the side of the hole, the nozzle guide defining the nozzle. Manufacturing method. Preparing a first substrate made of a porous medium; Stacking a second substrate on the first substrate; Forming a heater and a conductor connected to the heater between the material layers while forming a nozzle plate on the second substrate, the nozzle plate comprising a plurality of stacked material layers and having nozzles therethrough formed thereon; Etching the second substrate exposed through the nozzle to form an ink chamber filled with ink; And And forming a manifold for supplying ink to the back side of the first substrate. The method of claim 27, The first substrate is a method of manufacturing an inkjet printhead, characterized in that any one of a porous silicon substrate and a sintered metal plate. The method of claim 27, The second substrate is a method of manufacturing an inkjet printhead, characterized in that any one of a silicon substrate and a metal plate. The method of claim 27, And the first substrate and the second substrate are in close contact with each other. The method of claim 30, And the first substrate and the second substrate are bonded by an SDB method. The method of claim 27, And the first substrate and the second substrate are bonded to each other with a predetermined gap by an adhesive. Preparing a first substrate made of a porous medium; Forming an ink chamber in which ink is filled in the second substrate while stacking a second substrate made of metal on the first substrate; Forming a heater and a conductor connected to the heater between the material layers while forming a nozzle plate on the second substrate, the nozzle plate comprising a plurality of stacked material layers and having nozzles therethrough formed thereon; And And forming a manifold for supplying ink to the back side of the first substrate. The method of claim 33, The first substrate is a method of manufacturing an inkjet printhead, characterized in that any one of a porous silicon substrate and a sintered metal plate. The method of claim 33, wherein the stacking of the second substrate and forming the ink chamber, Forming a sacrificial layer for forming the ink chamber on the first substrate, and electroplating a predetermined metal material on the first substrate to form the second substrate, wherein the sacrificial layer Is removed through the nozzle after the nozzle plate forming step. The method of claim 33, wherein the stacking of the second substrate and forming the ink chamber, Forming the ink chamber through the second substrate made of a metal plate; bonding the second substrate on the first substrate; and filling a sacrificial layer in the ink chamber. And a sacrificial layer is removed through said nozzle after said nozzle plate forming step. The method of claim 35 or 36, And the sacrificial layer is made of any one of a photoresist and a photosensitive polymer. The method of claim 36, And the second substrate is bonded to the first substrate by a adhesive with a predetermined gap.