KR100503086B1 - Monolithic inkjet printhead and method of manufacturing thereof - Google Patents

Abstract

A monolithic inkjet printhead and a method of manufacturing the same are disclosed. The disclosed monolithic inkjet printhead comprises a silicon substrate having a manifold for ink supply, a photosensitive polymer layer integrally formed on the silicon substrate, an ink chamber filled with ink to be ejected, and an upper portion of the ink chamber. A flow passage plate defining a nozzle disposed to discharge ink from the ink chamber, an ink channel formed on the manifold, a restrictor connecting the ink chamber and the ink channel, a bottom plate of the ink chamber, A heater for heating the ink, and a wire electrically connected to the heater for applying a current to the heater. According to this configuration, the inkjet printhead can be implemented in a series of semiconductor processes on a single wafer, which not only solves the conventional problem of misalignment of the ink chamber and nozzle, but also simplifies the manufacturing process and enables mass production.

Description

Monolithic inkjet printhead and method of manufacturing thereof

The present invention relates to an inkjet printhead, and more particularly, to a thermally driven monolithic inkjet printhead integrally formed on a silicon substrate by a semiconductor process 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. As a result, bubbles are generated while the ink is boiled, and the generated bubbles expand to 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.

1A and 1B are cutaway perspective views illustrating the structure of an inkjet printhead disclosed in US Pat. No. 4,882,595, and a cross-sectional view for explaining an ink droplet ejection process, as an example of a conventional thermally driven inkjet printhead.

Referring to FIGS. 1A and 1B, a conventional thermally driven inkjet printhead includes a partition wall defining a substrate 10 and an ink chamber 26 provided on the substrate 10 and filled with ink 29. 14, a nozzle 12 provided with a heater 12 provided in the ink chamber 26, and a nozzle 16 through which ink droplets 29 'are discharged. When the current in the form of a pulse is supplied to the heater 12 to generate heat in the heater 12, the ink 29 filled in the ink chamber 26 is heated to generate bubbles 28. The generated bubbles 28 continue to expand, and thus pressure is applied to the ink 29 filled in the ink chamber 26 so that the ink droplets 29 'are discharged to the outside through the nozzle 16. Then, the ink 29 is sucked into the ink chamber 26 through the ink channel 24 from the manifold 22 and the ink chamber 26 is again filled with the ink 29.

However, in order to manufacture a conventional top-shooting inkjet printhead having such a structure, an ink chamber 26, an ink channel 24, and the like are formed on the substrate 10, and then on the substrate 10. Since the nozzle plate 18 on which the nozzle 16 is formed must be manufactured and bonded separately, a manufacturing process is complicated and a problem of misalignment may occur during bonding of the substrate 10 and the nozzle plate 18.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and in particular, provides a monolithic inkjet printhead having a novel structure in which the components can be integrally formed on a substrate by a semiconductor process. There is a purpose.

It is another object of the present invention to provide a method for manufacturing a monolithic inkjet printhead having the above structure.

The present invention to achieve the above technical problem,

A silicon substrate having a manifold for supplying ink;

An ink chamber formed of a photosensitive polymer layer integrally formed on the silicon substrate, filled with ink to be discharged, a nozzle disposed above the ink chamber to discharge ink from the ink chamber, and formed on the manifold; A flow path plate defining an ink channel and a restrictor connecting the ink chamber and the ink channel;

A heater disposed at a bottom of the ink chamber to heat ink inside the ink chamber; And

And a wire electrically connected to the heater to apply a current to the heater.

Here, it is preferable that the said photosensitive polymer is a polyimide.

Preferably, the wiring is connected to an end of the heater at the lower end of the side surface of the ink chamber.

In addition, the upper surface of the substrate is preferably formed with a space extending from the side of the manifold to the lower side of the ink chamber.

The present invention also provides a method of manufacturing a monolithic inkjet printhead having the above structure.

Method for producing a monolithic inkjet printhead according to the present invention,

(A) forming a heater layer on the silicon substrate, and then patterning the heater layer so as to remain only at a portion where an ink chamber is to be formed;

(B) forming a polysilicon layer on the substrate, and then patterning the polysilicon layer into planar shapes of ink chambers, restrictors, and ink channels;

(C) growing the polysilicon layer by an epitaxy process to form an epi-polysilicon layer;

(D) forming a contact hole on the side of the epi-polysilicon layer to expose the end of the heater layer;

(E) forming a wiring layer connected to the exposed end of the heater layer through the contact hole on the side of the epi-polysilicon layer of the portion where the ink chamber is to be formed;

(F) forming a flow path plate made of a photosensitive polymer layer surrounding the epi-polysilicon layer on the substrate;

(G) forming a nozzle on the photosensitive polymer layer;

(H) etching the epi-polysilicon layer through the nozzle to form an ink chamber, a restrictor and an ink channel; And

And (i) etching the back surface of the substrate to form a manifold connected to the ink channel.

In the step (a), it is preferable to form a first insulating layer on the upper surface of the substrate, and to form the heater layer on the first insulating layer.

After the forming of the second insulating layer on the heater layer and the first insulating layer before the step (b), the second insulating layer and the second insulating layer and the second insulating layer may be exposed to expose the substrate at the site where the restrictor and the ink channel are to be formed. And partially etching the insulating layer to remove the insulating layer.

In addition, before the step (d), forming a third insulating layer on the side of the epi-polysilicon layer; it is preferable to further include.

Further, in the step (e), after the wiring layer is formed, a fourth insulating layer may be formed on the outer surface thereof.

In addition, in the (bar) step, the photosensitive polymer layer may be formed to cover the upper surface of the epi-polysilicon layer to a predetermined thickness, and in the (g) step, the nozzle is the epi-polysilicon layer It may be formed to vertically penetrate the photosensitive polymer layer formed on the upper surface of the.

Meanwhile, in the step (bar), the epi-polysilicon layer is etched to form a trench having a predetermined depth around the site where the nozzle is to be formed, and then the epi-polysilicon layer is filled with the inside of the trench. The height of the polysilicon layer may be formed, and in the step (g), the nozzle may be formed by etching the epi-polysilicon layer surrounded by the trench. In this case, step (g) may be performed simultaneously with step (h).

In addition, in the step (g), the nozzle is preferably formed in a tapered shape in which the cross-sectional area gradually decreases toward the outlet.

In addition, in the step (a), the epi-polysilicon layer may be removed by isotropic dry etching. In this case, a space extended downward of the ink chamber may be formed on the upper surface of the substrate by the isotropic dry etching.

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.

2 is a schematic plan view of a monolithic inkjet printhead according to a preferred embodiment of the present invention, and FIGS. 3A and 3B show lines A-A 'and B-B', respectively, shown in FIG. Cross-sectional views showing the vertical structure of the monolithic inkjet printhead of the present invention.

First, referring to FIG. 2, in the inkjet printhead manufactured in a chip state, the ink ejection parts 100 are arranged in two rows, and bonding pads 109 electrically connected to the ink ejection parts 100 at both edges thereof. Is placed. In the drawing, the ink ejecting portions 100 are arranged in two rows, but may be arranged in one row or three or more rows to further increase the resolution. Although not shown, a power TR, a logic circuit, and the like are provided between the ink ejection parts 100 and the bonding pads 109 to drive each ink ejection part 100. Each ink discharge part 100 includes an ink chamber 105 filled with ink, a nozzle 106 through which ink is discharged, and a restrictor 104 connecting the ink chamber 105 and the ink channel 103. Prepared. With this configuration of the ink flow path, ink is supplied to each ink chamber 105 from the ink reservoir not shown through the ink channel 103 and the restrictor 104. Meanwhile, as shown, the restrictors 104 on both sides of the ink channel 103 are disposed to be offset from each other. This is to suppress cross talk between adjacent ink ejecting parts 100 in the ink ejecting process.

3A and 3B, the detailed structure of the monolithic inkjet printhead according to the present invention will now be described. The monolithic inkjet printhead according to the present invention has a structure in which the flow path plate 130 is integrally stacked on the silicon substrate 110. A manifold 102 is formed on the silicon substrate 110, and an ink channel 103, a restrictor 104, an ink chamber 105, and a nozzle 106 are formed on the flow path plate 130. The manifold 102, the ink channel 103, the restrictor 104, the ink chamber 105, and the nozzle 106 are sequentially connected to form an ink flow path. A heater 122 is disposed at the bottom of the ink chamber 105, and a wiring 127 is connected to the heater 122.

As the silicon substrate 110, a silicon wafer widely used in the manufacture of integrated circuits may be used. In the substrate 110, a manifold 102 connected to an ink reservoir (not shown) for storing ink is formed to vertically penetrate the substrate 100. The upper surface of the substrate 110 may include a space 112 extending downward of the ink chamber 105 on both sides of the manifold 102. This space 112 allows the heater 122 and the heat of the surroundings to be released more quickly as will be described later.

The flow path plate 130 surrounds the nozzle 106, the ink chamber 105, the restrictor 104, and the ink channel 103, and is formed as a photosensitive polymer layer integrally formed on the silicon substrate 110. Is done. Polyimide may be used as the photosensitive polymer.

The ink chamber 105 is a space filled with ink to be discharged, and receives ink from the manifold 102 through the ink channel 103 and the restrictor 104. The ink chamber 105 may have a rectangular cross-sectional shape as shown, but is not limited thereto, and may have a polygonal or circular planar shape.

At the bottom of the ink chamber 105, that is, the upper portion of the substrate 110, a heater 122 for supplying thermal energy for heating ink in the ink chamber 105 is disposed. The heater 122 is formed of a resistive heating element such as a tantalum-aluminum alloy, tantalum nitride, titanium nitride, and tungsten silicide. The heater 122 may be formed in a quadrangle like the ink chamber 105, or may be formed in another shape such as a polygon or a circle. In addition, the heater 122 is insulated from the ink in the substrate 110 and the ink chamber 105 by insulating layers 121 and 123 formed at upper and lower portions thereof. The insulating layers 121 and 123 may be formed of a silicon oxide film or a nitride film.

A wiring 127 for supplying current to the heater 122 is disposed at a lower side end portion of the ink chamber 105 and connected to an outer end of the heater 122. The wiring 127 may be made of a metal having excellent conductivity, such as aluminum or an aluminum alloy. The wiring 127 is insulated from the ink in the substrate 110, the flow path plate 130, and the ink chamber 105 by the insulating layers 121, 126, and 128 formed around the wiring 127. The insulating layers 121, 126, and 128 may also be formed of a silicon oxide film or a nitride film. Although not shown, a semiconductor element for driving a printhead, that is, a power TR or a logic circuit, is formed on an upper surface of the substrate 110, and the wiring 127 is connected to the driving circuit.

The ink channel 103 is disposed above the manifold to be perpendicular to the manifold 102 and formed on the same plane as the ink chamber 105. And. The ink channel 103 is disposed between the ink chambers 105 arranged in two rows.

The restrictor 104 is a passage connecting the ink channel 103 and the ink chamber 105 and is formed on the same plane as the ink chamber 105. In order to prevent the ink from flowing back due to the pressure at the time of ejection of the ink, the restrictor 104 preferably has a narrow width compared to the width of the ink chamber 105.

The nozzle 106 is a place where the ink is discharged from the ink chamber 105, and is vertically penetrated through a portion that forms the upper wall of the ink chamber 105 of the flow path plate 103. The nozzle 106 is disposed at a position corresponding to the center of the ink chamber 105, and its cross-sectional shape is preferably circular. On the other hand, the cross-sectional shape of the nozzle 106 may have a variety of shapes, such as elliptical or polygonal, not circular. The length of the nozzle 106 is preferably long enough because the straightness of the ink discharged through the nozzle 106 is improved.

The mechanism by which ink is ejected from the monolithic inkjet printhead according to the present invention having the structure as described above is as follows.

Referring to FIGS. 3A and 3B, when ink is filled in the ink chamber 105 and the nozzle 106, when a current in the form of a pulse is applied to the heater 122 through the wiring 127, the heater 122 may be used. Heat is generated. The generated heat is transferred to the ink inside the ink chamber 105, whereby the ink boils and bubbles are generated. The generated bubble expands with continuous supply of heat, and ink in the ink chamber 105 is discharged to the outside through the nozzle 106 by the expansion force of the bubble. Subsequently, when the applied current is cut off, the bubble cools and disappears while the ink is cooled, and the heat remaining in the heater 122 and its surroundings is conducted through the ink in the substrate 110 and the ink chamber 105 to be discharged. do. At this time, since the ink 112 is filled in the lower portion of the heater 122, the heat is discharged faster through this. Therefore, the temperature of the heater 122 and its surroundings can be returned to the initial state more quickly. During this process, the ink chamber 105 interior is refilled with ink supplied from the manifold 102 through the ink channel 103 and the restrictor 104. When refilling of the ink is completed and returned to the initial state, the above process is repeated.

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

4 to 22 are cross-sectional views for explaining step-by-step of a first embodiment of the method for manufacturing a monolithic inkjet printhead according to the present invention. In the drawings, the left figure is a sectional view along the line AA ′ shown in FIG. 2, and the right figure is a sectional view along the line B-B ′ shown in FIG.

First, referring to FIG. 4, in this embodiment, a silicon substrate is processed to a thickness of about 300 to 500 μm as the substrate 110. This is effective for mass production since the silicon wafer which is widely used in the manufacture of semiconductor devices can be used as it is.

On the other hand, shown in Figure 4 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.

In addition, the first insulating layer 121 is formed on the prepared upper surface of the silicon substrate 110. The first insulating layer 121 may be formed of a silicon oxide film or a nitride film. Such a silicon oxide film or nitride film may be formed by oxidizing the top surface of the substrate 110 or by depositing nitride on the top surface of the substrate 110.

Subsequently, the heater layer 122 is formed on the first insulating layer 121 formed on the upper surface of the substrate 110. The heater layer 122 sputters a resistive heating material such as tantalum-aluminum alloy, tantalum nitride, titanium nitride or tungsten silicide on the entire surface of the first insulating layer 121. It can be formed by depositing to a thickness of approximately 0.1 ~ 0.3㎛ by (sputtering), chemical vapor deposition (CVD) or the like.

Next, as shown in Figure 5, after applying the photoresist (PR) on the heater layer 122, it is patterned into a planar shape of the ink chamber (105 in Figure 2). The photoresist PR may be patterned by an exposure process and a developing process using a photomask. At this time, the photoresist PR is patterned slightly wider than the ink chamber 105. This is to allow the wiring layer 127 to be connected to the heater layer 122 when the wiring layer 127 is formed in the step of FIG. 14. The exposed portion of the heater layer 122 is etched and removed using the patterned photoresist PR as an etch mask, and then the photoresist PR is removed. Then, the heater layer 122 remains only at the portion where the ink chamber 105 is to be formed, and the first insulating layer 121 is exposed at other portions.

FIG. 6 illustrates a state in which a second insulating layer 123 is formed on the heater layer 122 and the exposed first insulating layer 121. The second insulating layer 123 may be formed of a silicon oxide film or a nitride film like the first insulating layer 121.

FIG. 7 illustrates a state in which the second insulating layer 123 and the first insulating layer 121 are partially etched and removed. Specifically, after applying the photoresist (PR) on the second insulating layer 123, and patterning it, the second insulating is located at the site where the restrictor (104 in FIG. 2) and the ink channel (103 in FIG. 2) will be formed Expose layer 123. The exposed portion of the second insulating layer 123 and the first insulating layer 121 below are etched using the patterned photoresist PR as an etching mask. At this time, the heater layer 122 is not exposed to the outside. Then, the silicon substrate 110 is exposed to the portion where the restrictor 104 and the ink channel 103 are to be formed. Subsequently, photoresist PR is removed.

Next, as shown in FIG. 8, a polysilicon layer 124 is deposited on the entire surface of the resultant product of FIG. 7. Subsequently, the photoresist PR is applied onto the polysilicon layer 124 and then patterned into a planar shape of the ink chamber 105, the restrictor 104, and the ink channel 103.

When the polysilicon layer 124 is etched using the patterned photoresist PR as an etch mask and the photoresist PR is removed, the second insulating layer 123 and the exposed portion are exposed as shown in FIG. 9. The polysilicon layer 124 having the planar shape of the ink chamber 105, the restrictor 104, and the ink channel 103 is formed on the silicon substrate 110.

FIG. 10 illustrates a state in which the polysilicon layer 124 is grown to a thick thickness by an epitaxial process. Specifically, the epi-polysilicon layer 125 is formed by growing the polysilicon layer 124 to a thick thickness, for example, a few tens of micrometers by an epitaxial process. At this time, the thickness of the epi-polysilicon layer 125 is determined in consideration of the height of the ink chamber 105 and the nozzle 106 to be formed later. In addition, the upper surface of the epi-polysilicon layer 125 may be planarized by a chemical mechanical polishing (CMP) process. The epi-polysilicon layer 125 formed as described above is removed in the step of FIG. 21 to form a space forming the nozzle 106, the ink chamber 105, the restrictor 104, and the ink channel 103 as described below. Act as a sacrificial layer.

Next, as shown in FIG. 11, after the photoresist PR is applied on the second insulating layer 123, the photoresist PR is patterned to expose the second insulating layer 123 of the edge portion of the head chip. Subsequently, the exposed second insulating layer 123 and the first insulating layer 121 below are etched using the photoresist PR as an etching mask, and then the photoresist PR is removed. Then, the silicon substrate 110 is exposed to the edge portion of the head chip.

In the state of FIG. 11, although not shown, a semiconductor device for driving a printhead, that is, a power TR or a logic circuit is formed on the exposed surface of the silicon substrate 110. Then, as shown in FIG. 12, the third insulating layer 126 is formed on the entire surface of the resultant product of FIG. 11. When the third insulating layer 126 forms the power TR or logic circuit, an interlayer dielectric (IMD) between the metal and the metal or an interlayer dielectric (ILD) between the metal and the gate or the active circuit is formed. It is formed as.

FIG. 13 illustrates a state in which a contact hole C for connecting the heater layer 122 and the semiconductor element is formed. Specifically, after the photoresist (PR) is applied to the entire surface of the third insulating layer 126, it is patterned by the upper surface and the outer side surface of the epi-polysilicon layer 125 of the third insulating layer 126 Expose the part formed in Subsequently, the exposed third insulating layer 126 and the second insulating layer 123 below are etched using the photoresist PR as an etching mask, and then the photoresist PR is removed. In this case, etching of the third insulating layer 126 and the second insulating layer 123 may be performed by anisotropic dry etching, for example, plasma etching or reactive ion etching. Then, the third insulating layer 126 formed on the upper surface of the epi-polysilicon layer 125 is removed, and the contact hole C is formed on the outer side of the epi-polysilicon layer 125, and the contact is formed. One end of the heater layer 122 is exposed through the hole C.

FIG. 14 illustrates a state in which the wiring layer 127 is connected to the heater layer 122 through the contact hole C. Referring to FIG. Specifically, the wiring layer 127 may be formed by depositing a metal having excellent electrical conductivity, such as aluminum or an aluminum alloy, on the entire surface of the resultant of FIG. 13 to a thickness of about 1 μm by sputtering or chemical vapor deposition. In this case, the wiring layer 127 is connected to the semiconductor device described above.

FIG. 15 illustrates a state in which the fourth insulating layer 128 is formed after the wiring layer 127 is patterned. Specifically, the wiring layer 127 is etched using the photoresist pattern as an etching mask, so that only portions connected to the heater layer 122 remain. Subsequently, an oxide film or a nitride film is deposited on the entire surface of the resultant product to form a fourth insulating layer 128.

Subsequently, as shown in FIG. 16, a fourth insulating layer formed on the upper surface of the epi-polysilicon layer 125 with photoresist PR ₁ in the space between and outside the epi-polysilicon layer 125. Up to a height of 128). Then, the coated photoresist (PR ₂₎ back onto the photoresist (PR ₁₎ and the fourth insulating layer 128 to a desired thickness.

Next, as shown in FIG. 17, the upper photoresist PR ₂ is patterned to partially expose the fourth insulating layer 128 formed on the upper surface of the epi-polysilicon layer 125. At this time, the exposed portion of the fourth insulating layer 128 is a portion corresponding to the circumference of the nozzle (106 in FIG. 2), the restrictor 104, and the ink channel 103.

Next, as shown in FIG. 18, the fourth insulating layer 128 exposed using the patterned upper photoresist PR ₂ as an etch mask, the epi-polysilicon layer 125 and the third insulating layer below it. The layer 126 is etched to a predetermined depth to form the trench 129. At this time, the trench 129 may be formed to be inclined so that the width becomes narrower toward the bottom. When the trench 129 having such a shape is formed, the nozzle 106 formed in the step of FIG. 21 has a tapered shape in which the cross-sectional area gradually decreases toward the outlet.

Next, as shown in FIG. 19, the upper photoresist PR ₂ and the lower photoresist PR ₁ are removed by ashing and stripping.

20 illustrates a state in which a flow path plate is formed of the photosensitive polymer layer 130. Specifically, a photosensitive polymer such as polyimide is filled to the height of the fourth insulating layer 128 formed on the upper surface of the epi-polysilicon layer 125 on the resultant surface of FIG. 19. Subsequently, the polyimide is exposed and cured, and the fourth insulating layer 128 is exposed at the portion corresponding to the nozzle 106. The photosensitive polymer layer 130 formed as described above serves as a flow path plate that surrounds and defines the nozzle 106, the ink chamber 105, the restrictor 104, and the ink channel 103.

Next, as illustrated in FIG. 21, when the fourth insulating layer 128 exposed on the upper surface of the photosensitive polymer layer 130 is etched and removed, the epi-polysilicon layer 125 is exposed. Subsequently, when the exposed epi-polysilicon layer 125 is etched away, the nozzle 106, the ink chamber 105, the restrictor 104, and the ink channel 103 surrounded by the photosensitive polymer layer 130 are removed. Is formed. At this time, the epi-polysilicon layer 125 may be etched by isotropic dry etching using XeF ₂ as a gas. Due to this isotropic etching characteristic, the silicon substrate 110 under the restrictor 104 and the ink channel 103 is also etched to a predetermined depth, and the substrate 110 under the first insulating layer 121 is also etched. Can be. Thus, as shown in the upper surface of the substrate 110, the space 112 is extended to the bottom of the ink chamber 105 is formed.

FIG. 22 illustrates a state in which a manifold 102 connected to the ink channel 103 is formed on a substrate 110. Specifically, the manifold 102 may be formed by forming an etching mask defining a portion to be etched on the rear surface of the substrate 110 and then etching the penetrating substrate 110 exposed by the etching mask. . Then, the manifold 102 is connected to the ink channel 103, and a portion of the space 112 extended below the ink chamber 105 remains on both sides of the upper end of the manifold 102.

Through the above steps, a monolithic inkjet printhead according to the present invention having a structure as shown in FIGS. 3A and 3B is completed.

23 and 24 are cross-sectional views for explaining step-by-step embodiments of a method for manufacturing a monolithic inkjet printhead according to the present invention. Since the manufacturing method according to the second embodiment is the same as the steps shown in FIGS. 4 to 15 of the above-described first embodiment, only the subsequent steps will be described.

After performing the process up to the steps of FIGS. 4 to 15, as shown in FIG. 23, a photosensitive polymer such as polyimide is coated on the entire surface of the resultant of FIG. 15 to form the photosensitive polymer layer 130. At this time, the photosensitive polymer layer 130 is formed sufficiently higher than the epi-polysilicon layer 125. That is, the photosensitive polymer layer 130 having a sufficient thickness is also formed on the epi-polysilicon layer 125. Subsequently, the photosensitive polymer layer 130 is selectively exposed and cured, and a nozzle 106 is formed above the epi-polysilicon layer 125 at the portion where the ink chamber 105 is to be formed. The formation of the nozzle 106 may be performed by a photolithography process.

Next, when the fourth insulating layer 128 exposed through the nozzle 106 is removed by etching, The epi-polysilicon layer 125 is exposed. Subsequently, when the exposed epi-polysilicon layer 125 is etched away, the nozzle 106, the ink chamber 105, and the restrictor 104 surrounded by the photosensitive polymer layer 130, as shown in FIG. 24, are removed. And an ink channel 103 is formed. In this case, the epi-polysilicon layer 125 may be etched by isotropic dry etching using XeF ₂ as an etching gas as in the first embodiment, and thus the top surface of the substrate 110. As in the first embodiment, a space 112 extended to the lower side of the ink chamber 105 is formed on the side.

Next, when the manifold 102 is formed on the substrate 110 as shown in FIG. 22 of the first embodiment described above, a mother according to the present invention having a structure as shown in FIGS. 3A and 3B is illustrated. The nolitic inkjet printhead is completed.

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, the method of laminating and forming each material is also merely illustrated, and various deposition methods and etching methods may be applied. 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, according to the present invention, since the flow path plate made of the silicon substrate and the photosensitive polymer is integrally formed, the inkjet printhead can be implemented by a series of semiconductor processes on a single wafer, and thus the ink chamber and the nozzle are misaligned. This not only eliminates this, but also simplifies the manufacturing process and enables mass production.

1A and 1B are cutaway perspective views and cross-sectional views illustrating an ink droplet ejection process showing an example of a conventional thermal drive inkjet printhead.

2 is a schematic plan view of a monolithic inkjet printhead according to a preferred embodiment of the present invention.

3A and 3B are sectional views showing the vertical structure of the monolithic inkjet printhead of the present invention along the lines A-A 'and B-B', respectively, shown in FIG.

4 to 22 are cross-sectional views for explaining step-by-step of a first embodiment of the method for manufacturing a monolithic inkjet printhead according to the present invention.

23 and 24 are cross-sectional views for explaining step-by-step embodiments of a method for manufacturing a monolithic inkjet printhead according to the present invention.

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

102 Manifold 103 Ink channel

104 ... Restrictor 105 ... Ink Chamber

106 Nozzle 110 Silicon Substrate

112 ... Expansion space 121,123,126,128 ... Insulation layer

122 Heater 124 Polysilicon layer

125 ... epi-polysilicon layer 127 ... wiring (layer)

130 ... Euro plate (photosensitive polymer layer)

Claims (19)

A silicon substrate having a manifold for supplying ink; An ink chamber formed of a photosensitive polymer layer integrally formed on the silicon substrate, filled with ink to be discharged, a nozzle disposed above the ink chamber to discharge ink from the ink chamber, and formed on the manifold; A flow path plate defining an ink channel and a restrictor connecting the ink chamber and the ink channel; A heater disposed at a bottom of the ink chamber to heat ink inside the ink chamber; And And a wire electrically connected to the heater to apply a current to the heater. And the wiring is connected to an end portion of the heater at a lower side end portion of the ink chamber. The method of claim 1, The photosensitive polymer is a monolithic inkjet printhead, characterized in that the polyimide. delete The method of claim 1, A monolithic inkjet printhead, characterized in that a space extending from the side of the manifold to the lower side of the ink chamber on the upper surface side of the substrate. The method of claim 1, And the heater is insulated from the ink in the substrate and the ink chamber by insulating layers formed on the bottom and top thereof. The method of claim 1, And wherein the wiring is insulated from the ink in the substrate, the flow path plate and the ink chamber by insulating layers formed around the wiring. The method of claim 1, And the restrictor is formed to have a width narrower than the width of the ink chamber. (A) forming a heater layer on the silicon substrate, and then patterning the heater layer so as to remain only at a portion where an ink chamber is to be formed; (B) forming a polysilicon layer on the substrate, and then patterning the polysilicon layer into planar shapes of ink chambers, restrictors, and ink channels; (C) growing the polysilicon layer by an epitaxy process to form an epi-polysilicon layer; (D) forming a contact hole on the side of the epi-polysilicon layer to expose the end of the heater layer; (E) forming a wiring layer connected to the exposed end of the heater layer through the contact hole on the side of the epi-polysilicon layer of the portion where the ink chamber is to be formed; (F) forming a flow path plate made of a photosensitive polymer layer surrounding the epi-polysilicon layer on the substrate; (G) forming a nozzle on the photosensitive polymer layer; (H) etching the epi-polysilicon layer through the nozzle to form an ink chamber, a restrictor and an ink channel; (I) etching the back of the substrate to form a manifold connected to the ink channel; manufacturing method of a monolithic inkjet printhead comprising a. The method of claim 8, In the step (a), a first insulating layer is formed on the upper surface of the substrate, the method of manufacturing a monolithic inkjet printhead, characterized in that to form the heater layer on the first insulating layer. The method of claim 9, Before the step (b), after the second insulating layer is formed on the heater layer and the first insulating layer, the second insulating layer and the first insulating layer are exposed so that the substrate at the site where the restrictor and the ink channel are to be formed is exposed. And partially etching the layer to remove the monolithic inkjet printhead. The method of claim 8, Before the step (d), forming a third insulating layer on the side of the epi-polysilicon layer; manufacturing method of a monolithic inkjet printhead, characterized in that it further comprises. The method of claim 8, In the step (e), after the wiring layer is formed, a fourth insulating layer is formed on an outer surface thereof, wherein the manufacturing method of the monolithic inkjet printhead. The method of claim 8, In the step (bar), wherein the photosensitive polymer is a polyimide manufacturing method of a monolithic inkjet printhead. The method of claim 8, In the step (bar), the photosensitive polymer layer is formed to cover the upper surface of the epi-polysilicon layer to a predetermined thickness, In the step (g), wherein the nozzle is formed so as to vertically penetrate the photosensitive polymer layer formed on the upper surface of the epi-polysilicon layer. The method of claim 8, In the step (bar), the epi-polysilicon layer is etched to form a trench having a predetermined depth around the site where the nozzle is to be formed, and then the epi-polysilicon is filled with the photosensitive polymer layer inside the trench. To the height of the layer, In the step (g), the nozzle is formed by etching the epi-polysilicon layer surrounded by the trench, the manufacturing method of the monolithic inkjet printhead. The method of claim 15, The step (g) is performed at the same time as the step (h) of the monolithic inkjet printhead manufacturing method. The method of claim 8, In the step (g), the nozzle is a manufacturing method of the monolithic inkjet printhead, characterized in that the tapered shape is gradually reduced in cross-sectional area toward the outlet. The method of claim 8, In the step (h), the epi-polysilicon layer is removed by the isotropic dry etching method of manufacturing a monolithic inkjet printhead. The method of claim 18, In the step (h), the isotropic dry etching method for producing a monolithic inkjet printhead, characterized in that the space extended to the lower side of the ink chamber on the upper surface of the substrate is formed.