Patent Grant
6984024
1. Field of the Invention
The present invention relates to an ink-jet printhead. More particularly, the present invention relates to a thermally driven monolithic ink-jet printhead in which a nozzle plate is formed integrally with a substrate and a manufacturing method thereof.
2. Description of the Related Art
In general, ink-jet printheads print a predetermined color image by repeatedly ejecting a small droplet of a printing ink at a desired position on a recording sheet. Ink-jet printheads are largely categorized into two types depending on the ink droplet ejection mechanisms: a thermally driven ink-jet printhead, in which a heat source is employed to form and expand bubbles in ink causing an ink droplet to be ejected, and a piezoelectrically driven ink-jet printhead in which a piezoelectric crystal bends to exert pressure on ink causing an ink droplet to be expelled.
An ink ejection mechanism of the thermally driven ink-jet printhead will now be described in detail. When a current pulse is applied to a heater consisting of a resistive heating material, heat is generated by the heater to rapidly heat ink near the heater to approximately 300° C. thereby causing the ink to boil and form bubbles. The formed bubbles expand to exert pressure on ink contained within an ink chamber. This pressure causes a droplet of ink to be ejected through a nozzle from the ink chamber.
A thermally driven ink-jet printhead can be further subdivided into top-shooting, side-shooting, and back-shooting types depending on the direction in which the ink droplet is ejected and the directions in which bubbles expand. While the top-shooting type refers to a mechanism in which an ink droplet is ejected in a direction the same as the direction in which the bubble expands, the back-shooting type is a mechanism in which an ink droplet is ejected in a direction opposite to the direction in which the bubble expands. In the side-shooting type, the direction of ink droplet ejection is perpendicular to the direction of bubble expansion.
Thermally driven ink-jet printheads need to meet the following conditions. First, a simple manufacturing process, low manufacturing cost, and mass production must be provided. Second, to produce high quality color images, a spacing between adjacent nozzles must be as small as possible while still preventing cross-talk between the adjacent nozzles. More specifically, to increase the number of dots per inch (DPI), many nozzles must be arranged within a small area. Third, for high speed printing, a cycle beginning with ink ejection and ending with ink refill must be as short as possible. That is, the heated ink and heater should cool down quickly to increase an operating frequency.
Referring to
The process of manufacturing a conventional top-shooting type ink-jet printhead configured as above involves separately manufacturing the nozzle plate 18 equipped with the nozzle 16 and the substrate 10 having the ink chamber 26 and ink feed channel 24 formed thereon and bonding them to each other. These required steps complicate the manufacturing process and may cause a misalignment during the bonding of the nozzle plate 18 with the substrate 10. Furthermore, since the ink chamber 26, the ink channel 24, and the manifold 22 are arranged on the same plane, there is a restriction on increasing the number of nozzles 16 per unit area, i.e., the density of nozzles 16. This restriction makes it difficult to implement a high printing speed, high resolution ink-jet printhead.
Recently, in an effort to overcome the above problems of conventional ink-jet printheads, ink-jet printheads having a variety of structures have been proposed.
Referring to
A conventional monolithic ink-jet printhead configured as above has an advantage in that the silicon substrate 30 is formed integrally with the nozzle plate 40 thereby simplifying the manufacturing process and eliminating the chance of a misalignment problem. Another advantage is that the nozzle 47, the ink chamber 32, the ink channel 34, and the manifold 36 are arranged vertically, which allows an increase in the density of nozzles 46 as compared with the ink-jet printhead of FIG. 1A.
In the monolithic ink-jet printhead shown in
As described above, the structure of the conventional monolithic ink-jet printhead has a restriction in realizing high-density nozzle arrangement in spite of recent increasing demand for ink-jet printheads capable of printing higher resolution of images with a high level of DPI (dot per inch).
It is a feature of an embodiment of the present invention to provide a thermally driven monolithic ink-jet printhead capable of printing higher resolution of images by including an ink chamber configured to reduce a spacing between adjacent nozzles.
It is another feature of an embodiment of the present invention to provide a method of manufacturing the monolithic ink-jet printhead.
In accordance with a feature of the present invention, there is provided a monolithic ink-jet printhead including a substrate having an ink chamber to be filled with ink to be ejected on a front surface, a manifold for supplying ink to the ink chamber on a rear surface, and an ink channel in communication with the ink chamber and the manifold, a barrier wall formed on the front surface of the substrate to a predetermined depth and defining at least a portion of the ink chamber in a width-wise direction, a nozzle plate including a plurality of material layers stacked on the substrate and having a nozzle penetrating the nozzle plate, so that ink ejected from the ink chamber is ejected through the nozzle, a heater formed between adjacent material layers of the plurality of material layers of the nozzle plate and located above the ink chamber for heating ink to be supplied within the ink chamber, and a conductor provided between adjacent material layers of the plurality of material layers of the nozzle plate, the conductor being electrically connected to the heater for applying current across the heater.
The barrier wall preferably surrounds at least a portion of the ink chamber so that the ink chamber is formed in a long, narrow shape. In addition, the barrier wall may surround the ink chamber in a rectangular shape or configuration. One side surface of the barrier wall may be preferably rounded.
The barrier wall is preferably formed of a metal, or an insulating material, such as silicon oxide or silicon nitride.
The nozzle is preferably provided at a width-wise center of the ink chamber. Preferably, the heater is located at a position of the nozzle plate above the ink chamber so as to avoid overlying the nozzle.
The ink channel may be provided at a location suitable to provide flow communication between the ink chamber and the manifold by perpendicularly penetrating the substrate. A cross-sectional shape of the ink channel is preferably circular, oval, or polygonal.
The nozzle plate may include a plurality of passivation layers sequentially stacked on the substrate and a heat dissipating layer made of a heat conductive metal for dissipating heat from the heater to the exterior of the ink-jet printhead. Preferably, the plurality of passivation layers include first through third passivation layers sequentially stacked on the substrate, the heater is formed between the first and second passivation layers, and the conductor is located between the second and third passivation layers.
The heat dissipating layer is preferably made of nickel, copper, or gold, and may be formed by electroplating to a thickness of 10-100 μm.
The nozzle plate may have a heat conductive layer located above the ink chamber, the heat conductive layer being insulated from the heater and conductor and contacting the substrate and heat dissipating layer.
The heat conductive layer is preferably made of a metal and may be made of the same metal and located on the same passivation layer as the conductor.
In addition to the above configuration, an insulating layer may be interposed between the conductor and the heat conductive layer.
Preferably, an upper part of the nozzle formed in the heat dissipating layer is tapered so that a cross-sectional area thereof decreases towards an upper end portion thereof.
In accordance with another feature of the present invention, there is provided a method of manufacturing a monolithic ink-jet printhead including (a) preparing a substrate, (b) forming a barrier wall made of a predetermined material different from a material of the substrate, (c) integrally forming a nozzle plate including a plurality of material layers and having a nozzle penetrating the plurality of material layers, and forming a heater and a conductor connected to the heater between the material layers, (d) forming an ink chamber defined by the barrier wall by isotropically etching the substrate exposed through the nozzle using the barrier wall as an etch stop, (e) forming a manifold for supplying ink by etching a rear surface of the substrate, and (f) forming an ink channel by etching the substrate so that it penetrates the substrate between the manifold and the ink chamber.
In (a), the substrate is preferably made of a silicon wafer.
In (b), the barrier wall may surround at least a portion of the ink chamber so that the ink chamber is formed in a long, narrow shape. Preferably, one side surface of the barrier wall is rounded. In addition, in (b), the barrier wall is preferably formed of a metal. In this case, the (b) may include forming an etch mask defining a portion to be etched on the front surface of the substrate, forming a trench by etching the substrate exposed through the etch mask to a predetermined depth, removing the etch mask, depositing a metal on the front surface of the substrate to fill the trench for forming the barrier wall, and forming a metal material layer made of the metal on the substrate, and removing the metal material layer formed on the substrate.
In (b), the barrier wall may be formed of an insulating material, such as silicon oxide or silicon nitride. In this case, (b) may include forming an etch mask defining a portion to be etched on the front surface of the substrate, forming a trench by etching the substrate exposed through the etch mask to a predetermined depth, removing the etch mask, and depositing the insulating material on the front surface of the substrate to fill the trench for forming the barrier wall, and forming an insulating material layer made of the insulating material on the substrate.
Further, (c) may include (c1) sequentially stacking a plurality of passivation layers on the substrate and forming the heater and the conductor between the passivation layers, and (c2) forming a heat dissipating layer made of a metal on the substrate and forming the nozzle so as to penetrate the passivation layers and the heat dissipating layer.
In this case, (c1) may include forming a first passivation layer on the substrate, forming the heater on the first passivation layer, forming a second passivation layer on the first passivation layer and the heater, forming the conductor on the second passivation layer, and forming a third passivation layer on the second passivation layer and the conductor. Preferably, the heater is formed in a rectangular shape.
In addition, in (c1), a heat conductive layer located above the ink chamber is preferably formed between the passivation layers, such that the heat conductive layer is insulated from the heater and conductor and contacts the substrate and heat dissipating layer. Preferably, the heat conductive layer is formed by depositing a metal to a predetermined thickness. The heat conductive layer may be formed of the same material with the conductor at the same time.
An insulating layer may be formed on the conductor, and the heat conductive layer may then be formed on the insulating layer.
The heat dissipating layer may be formed of nickel, copper, or gold, and is preferably formed by electroplating to a thickness of 10-100 μm.
Further, (c2) may include etching the passivation layers to form a lower nozzle with a predetermined diameter on a portion where the ink chamber is formed, forming a first sacrificial layer within the lower nozzle, forming a second sacrificial layer for forming an upper nozzle on the first sacrificial layer, forming the heat dissipating layer on the passivation layers by electroplating, and removing the second sacrificial layer and the first sacrificial layer, and forming a complete nozzle consisting of the lower and upper nozzles.
The lower nozzle is preferably formed by dry etching the passivation layers using reactive ion etching (RIE).
In addition, after a seed layer for electroplating the heat dissipating layer is formed on the first sacrificial layer and passivation layers, the second sacrificial layer may be formed.
After the lower nozzle is formed and a seed layer for electroplating the heat dissipating layer is formed on the substrate exposed by the passivation layers and lower nozzle, the first sacrificial layer and the second sacrificial layer may be formed sequentially or integrally with each other.
The method may further comprise planarizing the top surface of the heat dissipating layer by chemical mechanical polishing (CMP) after forming the heat dissipating layer.
In (d), horizontal etching may be stopped and only vertical etching may be performed around the barrier wall due to the presence of the barrier wall serving as an etch stop.
In (f), the substrate may be dry etched by reactive ion etching (RIE) from the rear surface of the substrate on which the manifold has been formed to form the ink channel.
In the present invention, since a narrow, long, deep ink chamber is formed using a barrier wall serving as an etch stop, a spacing between adjacent nozzles can be reduced, thereby realizing an ink-jet printhead capable of printing higher resolution of images with a high level of DPI. In addition, since a nozzle plate having a nozzle is formed integrally with a substrate having an ink chamber and an ink channel formed thereon, the ink-jet printhead can be realized on a single wafer in a single process.
The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail preferred embodiments thereof with reference to the attached drawings in which:
Korean Patent Application No. 2002-62258, filed on Oct. 12, 2002, and entitled: “Monolithic Ink-Jet Printhead Having an Ink Chamber Defined by a Barrier Wall and Manufacturing Method Thereof,” is incorporated by reference herein in its entirety.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thickness of layers and regions and the sizes of components may be exaggerated for clarity. It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like elements throughout.
Referring to
In the ink-jet printhead fabricated in a chip state, as shown in
Here, a silicon wafer widely used to manufacture integrated circuits (ICs) may be used as the substrate 110.
In the present invention, the ink chamber 132 is defined by a barrier wall 131. The barrier wall 131 is formed on the front surface of the substrate 110 to a predetermined depth in consideration of the depth of the ink chamber 132, for example, between about several micrometers to several tens micrometers.
Since the shape of a plane surrounded by the barrier wall 131 may be rectangular, the ink chamber 132 is narrow, long and deep. Thus, the ink chamber 132 is capable of accommodating ink enough to eject ink droplets even if it is narrow in a direction in which nozzles are arranged. If the width of the ink chamber 132 is small, a spacing between adjacent nozzles 138 is reduced, so that a high-density arrangement of the nozzles 138 may be provided, thereby achieving an ink-jet printhead with print resolution of a high level of DPI.
The rectangular barrier wall 131 surrounding the ink chamber 132 may be separately provided at each of the plurality of the ink chambers 132, and a part of the barrier wall 131 positioned between adjacent ink chambers 132 can be shared by the adjacent ink chambers 132. In this case, the part of the barrier wall 131 positioned between adjacent ink chambers 132 is thick in order to withstand pressure changes in the ink chamber 132, for example, a thickness of the barrier wall 131 may be about several micrometers.
As described above, within the range in which the width of the ink chamber 132 is defined, the plane surrounded by the barrier wall 131 may take various shapes other than a rectangle, which will later be described.
The barrier wall 131 is formed of a different material from the substrate 110, which allows the barrier wall 131 to serve as an etch stop in the process of forming the ink chamber 132, which will be described below. Thus, if the substrate 110 is a silicon wafer, the barrier wall 131 may be formed of an insulating material such as silicon oxide or silicon nitride, which is advantageous in that the same material can be used for both the barrier wall 131 and a first passivation layer 121. The barrier wall 131 may alternately be formed of a metal material, which is advantageous in that heat inside the ink chamber 132 can be dissipated through the barrier wall 131 relatively rapidly.
The ink channel 134 can be formed perpendicularly at a position deviating from the center of the ink chamber 132, that is, at a peripheral portion of the ink chamber 132. Thus, the ink channel 134 is positioned under the heater 142, rather than under the nozzle 138.
The cross-section of the ink channel 134 is preferably shaped of a rectangle elongated in a width direction of the ink chamber 132. In addition, the ink channel 134 may have various cross-sectional shapes such as circular, oval or polygonal.
In addition, the ink channel 134 may be formed at any location other than under the heater 142 that can connect the ink chamber 132 with the manifold 136 by perpendicularly penetrating the substrate 110.
A nozzle plate 120 is formed on the substrate 110 having the ink chamber 132, the ink channel 134, and the manifold 136 formed thereon. The nozzle plate 120, which forms an upper wall of the ink chamber 132, includes the nozzle 138, through which ink is ejected. The nozzle 138 is formed in the width-wise center of the ink chamber 132 by perpendicularly penetrating the nozzle plate 120.
The nozzle plate 120 is comprised of a plurality of material layers stacked on the substrate 110. The plurality of material layers may consist of first, second and third passivation layers 121, 122 and 126. Preferably, the plurality of material layers further includes a heat dissipating layer 128 made of a metal. More preferably, the plurality of material layers further includes a heat conductive layer 124. The heater 142 is provided between the first and second passivation layers 121 and 122, and a conductor 144 is provided between the second and third passivation layers 122 and 126.
The first passivation layer 121, the lowermost layer among the plurality of material layers forming the nozzle plate 120, is formed on the front surface of the substrate 110. The first passivation layer 121 for providing electrical insulation between the overlying heater 142 and underlying substrate 110, as well as for protecting the heater 142, may be made of silicon oxide or silicon nitride. In particular, in the case where the barrier wall 131 is made of an insulating material, the first passivation layer 121 and the barrier wall 131 are preferably formed of the same material.
The heater 142 overlying the ink chamber 132 to heat ink inside the ink chamber 132 is formed on the first passivation layer 121. The heater 142 consists of a resistive heating material, such as polysilicon doped with impurities, tantalum-aluminum alloy, tantalum nitride, titanium nitride, and tungsten silicide. The heater 142 may be rectangular. Further, the heater 142 is located at a position above the ink chamber 132 so as to avoid overlaying the nozzle 138, that is, at a location deviating from the center of the ink chamber 132. More specifically, since the nozzle 138 is formed to one side of the lengthwise center of the ink chamber 132, the heater 142 is disposed to the other side of the lengthwise center of the ink chamber 132.
The second passivation layer 122 is formed on the first passivation layer 121 and the heater 142 for providing insulation between the overlying heat conductive layer 124 and the underlying heater 142, as well as for protecting the heater 142. Similarly to the first passivation layer 121, the second passivation layer 122 may be made of silicon nitride and silicon oxide.
The conductor 144 electrically connected to the heater 142 for applying a current pulse across the heater 142 is placed on the second passivation layer 122. While a first end of the conductor 144 is coupled to the heater 142 through a first contact hole C1 formed in the second passivation layer 122, a second end is electrically connected to a bonding pad (not shown). The conductor 144 may be made of a highly conductive metal such as aluminum, aluminum alloy, gold, or silver.
The heat conductive layer 124 may overlie the second passivation layer 122. The heat conductive layer 124 functions to conduct heat residing in or around the heater 142 to the substrate 110 and the heat dissipating layer 128 which will be described later, and is preferably formed as widely as possible to cover the ink chamber 132 and the heater 142 entirely, as shown in FIG. 5. The heat conductive layer 124 needs to be spaced apart a predetermined distance from the conductor 144 to provide insulation. The insulation between the heat conductive layer 124 and the conductor 144 can be achieved by the second passivation layer 122 interposed therebetween. Furthermore, the heat conductive layer 124 contacts the top surface of the substrate 110 through a second contact hole C2 penetrating the first and second passivation layers 121 and 122.
The heat conductive layer 124 is made of a metal having good conductivity. When both heat conductive layer 124 and the conductor 144 are formed on the second passivation layer 122, the heat conductive layer 124 may be made of the same material as the conductor 144, such as aluminum, aluminum alloy, gold, or silver.
To form the heat conductive layer 124 having a greater thickness than the conductor 144 or to form the heat conductive layer 124 using a different metal material from the conductor 144, an insulating layer (not shown) may be provided between the conductor 144 and the heat conductive layer 124.
The third passivation layer 126 overlying the conductor 144 and the second passivation layer 122 may be made of tetraethylorthosilicate (TEOS) oxide or silicon oxide. It is desirable to avoid forming the third passivation layer 126 over the heat conductive layer 124 to avoid contacting the heat conductive layer 124 and the heat dissipating layer 128.
The heat dissipating layer 128, the uppermost layer from among the plurality of material layers forming the nozzle plate 120, is made of a metal having high thermal conductivity such as nickel, copper, or gold. The heat dissipating layer 128 is formed as thickly as about 10-100 μm by electroplating the metal on the third passivation layer 126 and the heat conductive layer 124. To accomplish this formation, a seed layer 127 for electroplating the metal is disposed on top of the third passivation layer 126 and the heat conductive layer 124. The seed layer 127 may be made of a metal having good electric conductivity such as copper, chrome, titanium, gold or nickel.
Since the heat dissipating layer 128 made of a metal as described above is formed by a electroplating process, it can be formed integrally with other components of the ink-jet printhead and relatively thickly, thus providing effective heat dissipation.
The heat dissipating layer 128 functions to dissipate the heat from the heater 142 or from around the heater 142 to the outside. More specifically, the heat residing in or around the heater 142 after ink ejection is guided to the substrate 110 and the heat dissipating layer 128 via the heat conductive layer 124 and then dissipates to the outside. This allows quick heat dissipation after ink ejection and lowers the temperature near the nozzle 138, thereby providing stable printing at a high operating frequency.
A relatively thick heat dissipating layer 128 as described above makes it possible to sufficiently secure the length of the nozzle 138, which enables stable high speed printing while improving the directionality of an ink droplet being ejected through the nozzle 138. Thus, the ink droplet can be ejected in a direction exactly perpendicular to the substrate 110.
The nozzle 138, consisting of a lower part 138a and an upper part 138b, is formed in and penetrates the nozzle plate 120. The lower part 138a of the nozzle 138 is formed in a pillar shape by penetrating the passivation layers 121, 122, and 126 of the nozzle plate 120. The upper part 138b of the nozzle 138 is formed in and penetrates the heat dissipating layer 128. The upper part 138b of the nozzle 138 may also be formed in a pillar shape. However, the upper part 138b is preferably tapered so that a cross-sectional area decreases toward an upper opening thereof. If the upper part 138b has a tapered shape as described above, a meniscus in the ink surface is more quickly stabilized after ink ejection.
Referring to
Referring to
Referring to
According to this fourth embodiment, a nozzle 438 is provided at the lengthwise center of the ink chamber 432. A heater 442 formed on a first passivation layer 421 may be rectangular. The heater 442 may be located to one side of the nozzle 438. However, the heater 442 may also be located at on opposite sides of the nozzle 438. In addition, the heater 442 may be formed such that it surrounds the nozzle 438. The shapes and arrangement of other components of the ink-jet printhead, that is, an ink channel 434 and a manifold 436, are the same as those in the above-described third embodiment.
An ink ejection mechanism in the ink-jet printhead shown in
First, referring to
Referring to
A meniscus in the surface of the ink 150 retreats toward the ink chamber 132 after ink droplet 150′ separation. In this case, the nozzle 138 is sufficiently long due to the thick nozzle plate 120 so that the meniscus retreats only within the nozzle 138 and not into the ink chamber 132. Thus, this prevents air from flowing into the ink chamber 132 while quickly restoring the meniscus to an original state, thereby stably maintaining high speed ejection of the ink droplet 150′. Furthermore, since heat residing in or around the heater 142 is dissipated into the substrate 110 or to the outside by conduction heat transfer through the heat conductive layer 124 and the heat dissipating layer 128, the temperature in or around the heater 142 and nozzle 138 drops more quickly. Here, if the barrier wall 131 is made of a metal material, heat dissipation is performed even more rapidly.
Next, referring to
A method of manufacturing a monolithic ink-jet printhead configured above according to a preferred embodiment of this invention will now be described.
Referring to
While
An etch mask 112 that defines a portion to be etched is formed on the surface of the substrate 110. The etch mask 112 can be formed by coating a photoresist on the front surface of the substrate 110 and patterning the same.
The substrate 110 exposed by the etch mask 112 is then etched to form a trench 114 having a predetermined depth. The substrate 110 is dry-etched by reactive ion etching (RIE). The depth of the trench 114 is determined to be in the range of about several micrometers to several tens micrometers in consideration of the depth of the ink chamber (132 of FIG. 21). The width of the trench 114 is in the range of about several micrometers, i.e., wide enough so that a predetermined material may easily be filled therein. The trench 114 surrounds a portion where the ink chamber 132 is to be formed in a rectangular shape. In the ink chamber 232, 332 or 432 shown in
After forming the trench 114, the etch mask 112 on the substrate 110 is removed. As shown in
If the barrier wall 131 and the material layer 116 are made of an insulating material like the first passivation layer 121, shown in
If the barrier wall 131 and the material layer 116 are made of a metallic material, the material layer 116 on the substrate 110 is etched for removal, and then steps shown in
As shown in
The heater 142 is then formed on the first passivation layer 121 overlying the substrate 110. The heater 142 is formed by depositing a resistive heating material, such as polysilicon doped with impurities, tantalum-aluminum alloy, tantalum nitride, titanium nitride, or tungsten silicide, over the entire surface of the first passivation layer 121 to a predetermined thickness and patterning the same in a predetermined shape, e.g., in a rectangular shape. Specifically, while the polysilicon doped with impurities, such as phosphorus (P) contained in a source gas, can be deposited by low pressure chemical vapor deposition (LPCVD) to a thickness of approximately 0.7-1 μm, tantalum-aluminum alloy, tantalum nitride, titanium nitride, or tungsten silicide may be deposited by sputtering or chemical vapor deposition (CVD) to a thickness of about 0.1-0.3 μm. The deposition thickness of the resistive heating material may be determined in a range other than the range given here to have an appropriate resistance considering the width and length of the heater 142. The resistive heating material deposited over the entire surface of the first passivation layer 121 can be patterned by a lithography process using a photomask and a photoresist and an etching process using a photoresist pattern as an etch mask.
Then, as shown in
If the heat conductive layer 124 is to be formed more thickly than the conductor 144 or if the heat conductive layer 124 is to be made of a metal other than that of the conductor 144, or to further ensure insulation between the conductor 144 and heat conductive layer 124, the heat conductive layer 124 can be formed after having formed the conductor 144. More specifically, after forming only the first contact hole C1, the conductor 144 is formed. An insulating layer (not shown) would then be formed on the conductor 144 and second passivation layer 122. The insulating layer can be formed from the same material using the same method as the second passivation layer 122. The insulating layer and the second and first passivation layers 122 and 121 are then sequentially etched to form the second contact hole C2. The heat conductive layer 124 would then be formed. Thus, the insulating layer is interposed between the conductor 144 and the heat conductive layer 124.
As shown in
Meanwhile, if a pillar-shaped upper nozzle 138b is to be formed, the second sacrificial layer PR2 is also formed in a pillar-shape. The first and second sacrificial layers PR1 and PR2 can then be made from a photosensitive polymer instead of a photoresist.
Then, as shown in
Since the surface of the heat dissipating layer 128 that has undergone electroplating has irregularities due to the underlying material layers, it may be planarized by chemical mechanical polishing (CMP).
The second sacrificial layer PR2 for forming the upper nozzle 138b, the underlying seed layer 127, and the first sacrificial layer PR1 for maintaining the lower nozzle 138a are then sequentially etched to form the complete nozzle 138 by connecting the lower and upper nozzles 138a and 138b and the nozzle plate 120 comprised of the plurality of material layers.
Alternatively, the nozzle 138 and the heat dissipating layer 128 may be formed through the following steps. Referring to
After having undergone the above steps, a monolithic ink-jet printhead according to an embodiment of the present invention having an ink chamber 132 defined by the barrier wall 131 is completed, as shown in FIG. 22.
As described above, according to the present invention, an ink chamber having various shapes adapted to the shape of a barrier wall can be formed. In particular, since a narrow, long ink chamber is formed, a spacing between adjacent nozzles can be reduced.
As described above, the monolithic ink-jet printhead and the manufacturing method thereof according to the present invention have the following advantages.
First, a narrow, long, deep ink chamber can be formed by forming a barrier wall serving as an etch stop. Thus, a spacing between adjacent nozzles can be reduced, thereby realizing an ink-jet printhead capable of printing higher resolution of images with a high level of DPI.
Second, since a nozzle, an ink chamber and an ink channel are not coupled to each other in view of shape and dimension, the degree of freedom is high in the design and manufacture of the ink-jet printhead, thereby easily improving the ink ejection performance and operating frequency.
Third, the present invention improves heat sinking capability due to the presence of a barrier wall made of a metal or a heat dissipation layer made of a thick metal, thereby increasing the ink ejection performance and operating frequency. Also, a sufficient length of the nozzle can be secured so that a meniscus is maintained within the nozzle, thereby allowing stable ink refill operation while increasing the directionality of an ink droplet being ejected.
Fourth, according to the present invention, since a nozzle plate having a nozzle is formed integrally with a substrate having an ink chamber and an ink channel formed thereon, the invention can provide an ink-jet printhead on a single wafer using a monolithic process. This provision eliminates the conventional problems of misalignment between the nozzle and ink chamber, thereby increasing the ink ejection performance and manufacturing yield.
Preferred embodiments of the present invention have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. For example, materials used to form each element of a printhead according to this invention may not be limited to those described herein. That is, the substrate may be formed of a material having good processibility, other than silicon, and the same is true of a heater, a conductor, a passivation layer, a heat conductive layer, or a heat dissipating layer. In addition, the stacking and formation method for each material are only examples, and a variety of deposition and etching techniques may be adopted. Furthermore, specific numeric values illustrated in each step may vary within a range in which the manufactured printhead can operate normally. In addition, sequence of process steps in a method of manufacturing a printhead according to this invention may differ. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | Kind |
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| 10-2002-0062258 | Oct 2002 | KR | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20040075716 A1 | Apr 2004 | US |
