KR20050056000A - Monolithic inkjet printhead having two pairs of heaters and manufacturing method thereof - Google Patents

Abstract

An integrated inkjet printhead with two pairs of heaters and a method of manufacturing the same are disclosed. The disclosed inkjet printhead comprises: a substrate having an ink chamber filled with ink to be discharged, a manifold for supplying ink to the ink chamber, and an ink channel connecting the ink chamber and the manifold; A nozzle plate comprising a plurality of material layers stacked on the substrate, the nozzle plate penetrating through the nozzle connected to the ink chamber; A first heater pair and a second heater pair provided inside the nozzle plate so as to be positioned above the ink chamber and driven independently of each other disposed around the nozzle; And a first conductor and a second conductor provided inside the nozzle plate and connected to the first heater pair and the second heater pair, respectively, to supply current to the first heater pair and the second heater pair, respectively. According to the present invention, since the two pairs of heaters can be used alternately, the life of the printhead is extended, and ink droplets having different volumes can be discharged by the combination of the two pairs of heaters, thereby improving print quality. You can.

Description

Monolithic inkjet printhead having two pairs of heaters and manufacturing method

The present invention relates to a thermally driven inkjet printhead, and more particularly, to an integrated inkjet printhead having two pairs of heaters and a manufacturing method thereof.

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 thermal inkjet printhead of a thermal type that generates bubbles in the ink by using a heat source and ejects ink droplets by the expansion force of the bubbles. A piezoelectric type inkjet printhead which ejects ink droplets by pressure applied to the ink due to deformation.

The ink droplet ejection mechanism of the thermally driven inkjet printhead will be described in detail as follows. When a pulse-type current flows to a heater made of a resistive heating element, as the heat is generated from the heater and the ink adjacent to the heater is instantaneously heated, ink is boiled and bubbles are generated, and the generated bubbles expand and are filled in the ink chamber. Pressure is applied. 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. In other words, the heated ink must be cooled quickly to increase the driving frequency.

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

Referring to FIGS. 1A and 1B, a conventional thermal drive 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, ink 29 is sucked from the manifold 22 through the ink channel 24 into the ink chamber 26 so that 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, the nozzle plate 18 having the nozzles 16 formed thereon must be separately manufactured and bonded on the substrate 10 having the partitions 14 formed thereon. Therefore, there is a disadvantage that a manufacturing process is complicated and a problem of misalignment may occur during bonding of the nozzle plate 18 and the substrate 10. In addition, since the ink chamber 26, the ink channel 24, and the manifold 22 are disposed on a plane, there is a limit to increasing the number of nozzles 16, i.e., the nozzle density, per unit area, and thus high printing. It is difficult to implement inkjet printheads with speed and high resolution.

Recently, in order to solve the problems of the conventional inkjet printhead as described above, inkjet printheads having various structures have been proposed, and as an example thereof, FIGS. The monolithic inkjet printhead disclosed in the applicant's Korean patent application published as 2002-007741 is shown. have.

2A and 2B, 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. At the bottom of the ink chamber 32, an ink channel 34 connecting the ink chamber 32 and the manifold 36 is formed therethrough. 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 at a position corresponding to the center of the ink chamber 32 in the nozzle plate 40, and a heater 45 connected to the electrode 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 compared to the inkjet printhead shown in Figure 1a.

However, in the conventional thermal drive inkjet printhead having the structure as described above, the heater may be damaged or damaged due to cavitation damage or electro-migration. In this case, since the normal operation of the print head becomes difficult, it is difficult to print a high resolution image and the life of the print head is shortened. Herein, cavitation damage means that when the expanded bubble contracts and disappears rapidly as the energy supply from the heater ceases, the heater at that site is damaged by a very high pressure acting on the site where the bubble finally dissipates. Say that you are wearing.

On the other hand, in recent years, a printhead having a structure in which a pair of rectangular heaters are arranged on both sides of the nozzle and a pair of heaters are connected in parallel has been proposed. However, even in this case, when one of the heaters is damaged or broken, the generation of bubbles is incomplete, and thus the normal ink ejection performance cannot be obtained, and the other heater can also be easily broken by the overcrowded current.

The present invention was created to solve the problems of the prior art as described above, in particular, by placing two pairs of heaters independently driven on both sides of the nozzle can increase the life, by a combination of two pairs of heaters An object of the present invention is to provide an integrated inkjet printhead capable of ejecting ink droplets having different volumes and a method of manufacturing the same.

An integrated inkjet printhead according to the present invention for achieving the above technical problem,

A substrate having an ink chamber filled with ink to be discharged, a manifold for supplying ink to the ink chamber, and an ink channel connecting the ink chamber and the manifold;

A nozzle plate formed of a plurality of material layers stacked on the substrate and formed by penetrating a nozzle connected to the ink chamber;

A first heater pair and a second heater pair provided inside the nozzle plate so as to be positioned above the ink chamber and driven independently of each other and disposed around the nozzle; And

A first conductor and a second conductor provided inside the nozzle plate and connected to the first heater pair and the second heater pair, respectively, for supplying current to the first heater pair and the second heater pair, respectively; It is characterized by.

Here, the first heater pair and the second heater pair are preferably arranged to be staggered around the nozzle. In this case, two unit heaters constituting the first heater pair may be disposed on one diagonal of the ink chamber, and two unit heaters constituting the second heater pair may be disposed on another diagonal of the ink chamber. Can be.

The two unit heaters constituting the first heater pair are preferably connected in series to the first conductor, and the two unit heaters constituting the second heater pair are connected in series to the second conductor.

The unit conductors constituting the first conductor and the unit conductors constituting the second conductor may be divided into two layers. In this case, the plurality of material layers constituting the nozzle plate may include first, second, third and fourth protective layers, and the first heater pair and the second heater pair are formed on the first protective layer. Some of the unit conductors may be disposed on the second passivation layer, and other portions of the unit conductors may be disposed on the third passivation layer.

The size of the first heater pair and the second heater pair may be the same or different.

The ink chamber is preferably surrounded by sidewalls formed to a predetermined depth from the surface of the substrate.

The nozzle plate preferably includes a plurality of protective layers stacked on the substrate, and a heat dissipation layer made of a thermally conductive metal material stacked on the protective layer.

A thermal conductive layer may be provided between the first and second heater pairs and the first and second conductors to contact the substrate and the heat dissipating layer between the plurality of protective layers. In this case, the heat conductive layer may be made of the same metal material as the first and second conductors.

The heat dissipation layer may be in thermal contact with the surface of the substrate through contact holes formed in the passivation layers. The heat dissipation layer may be formed by electroplating. For this purpose, a seed layer for electroplating the heat dissipation layer may be formed on the protective layers.

And, the manufacturing method of the integrated inkjet printhead according to the present invention for achieving the above technical problem,

(A) preparing a substrate;

(B) forming sidewalls of a material different from a material forming the substrate in the substrate;

(C) integrally forming a nozzle plate on the substrate, the nozzle plate consisting of a plurality of stacked material layers and having nozzles therethrough, disposed around the nozzles between the material layers and driven independently of one another; A first conductor and a second conductor connected to the first heater pair and the second heater pair and the first heater pair and the second heater pair respectively to supply current to the first heater pair and the second heater pair, respectively. Forming;

(D) isotropically etching the substrate exposed through the nozzle while using the sidewall as an etch stop wall to form an ink chamber defined by the sidewall;

(E) forming a manifold for supplying ink by etching the rear surface of the substrate; And

(F) forming an ink channel by etching through the substrate between the manifold and the ink chamber to form an ink channel.

In the step (a), the substrate may be made of a silicon wafer.

The step (b) may include forming an etching mask defining a portion to be etched on the upper surface of the substrate; Etching the substrate exposed through the etching mask to a predetermined depth to form a trench; Removing the etch mask; And filling the inside of the trench to form the sidewalls by depositing a material different from the material of the substrate on the surface of the substrate.

In the step (c), (a-1) the plurality of protective layers are sequentially stacked on the substrate, and the first and second heater pairs and the first and second conductors Forming between; And (c-2) forming the heat dissipating layer made of a metal on the protective layers while penetrating the nozzles through the protective layers and the heat dissipating layer.

The step (c-1) may include forming a first protective layer on an upper surface of the substrate; Forming the first heater pair and the second heater pair on the first protective layer; Forming a second protective layer on the first protective layer; Forming a portion of the first conductor and the second conductor on the second protective layer; Forming a third passivation layer on the second passivation layer; Forming a remaining portion of the first conductor and the second conductor on the third protective layer; And forming a fourth protective layer on the third protective layer.

Here, a heat conductive layer may be formed on the second protective layer and the third protective layer to be insulated from the first and second heater pairs and the first and second conductors and to contact the substrate and the heat dissipation layer. The heat conductive layer may be formed of the same metal material as the first and second conductors.

In the step (c-2), the heat dissipation layer may be made of any one metal of nickel, copper, aluminum and gold, and is preferably formed to have a thickness of 10 to 100 μm by electroplating.

Step (c-2) may include forming a lower portion of the nozzle by etching the passivation layers having a predetermined diameter on an upper portion of the portion where the ink chamber is to be formed; Forming a sacrificial layer inside the nozzle; Forming a seed layer for electroplating the heat dissipating layer on the sacrificial layer and the protective layer; Forming a plating mold for forming an upper portion of the nozzle on the seed layer; Forming the heat dissipating layer on the seed layer by electroplating; And removing the plating mold, the seed layer under the plating mold, and the sacrificial layer to form the nozzle.

Here, the sacrificial layer and the plating frame may be made of a photoresist or a photosensitive polymer, and the plating frame is preferably formed in a tapered shape whose cross-sectional area is gradually narrowed upward.

And, 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.

In the step (bar), it is preferable to dry-etch the substrate on the back side of the substrate on which the manifold is formed to form the ink channel by reactive ion 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.

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

Referring to FIG. 3, a plurality of nozzles 108 are arranged in two rows on the surface of an inkjet printhead manufactured in a chip state, and bonding pads 101 to be bonded to wires are disposed at both edge portions thereof. In the drawing, although the nozzles 108 are arranged in two rows, they may be arranged in one row, or may be arranged in three or more rows to further increase the resolution.

FIG. 4 is a plan view of an integrated inkjet printhead according to a preferred embodiment of the present invention, in which the portion B of FIG. 3 is enlarged, showing a layout structure of two pairs of heaters and a conductor, and FIG. 5 is shown in FIG. Vertical cross-sectional view of an integrated inkjet printhead according to a preferred embodiment of the present invention along the line X-X '.

4 and 5 together, the inkjet printhead according to the present invention is a manifold 102, ink channel 104, ink chamber 106 and nozzle 108 from an ink reservoir (not shown) containing ink. Has an ink flow path leading to

The manifold 102 is formed on the back side of the substrate 110 and is connected to an ink reservoir (not shown) containing ink. Thus, the manifold 102 serves to supply ink from the ink reservoir to the ink chamber 106.

Here, the wafer 110 may be a silicon wafer widely used in the manufacture of semiconductor devices.

The ink channel 104 is formed by vertically penetrating the substrate 110 between the ink chamber 106 and the manifold 102. Only one ink channel 104 may be formed at a position corresponding to the center of the ink chamber 106. Meanwhile, two ink channels 104 may be formed at both edge portions of the ink chamber 106. As such, the ink channel 104 may be formed at any position where the ink chamber 106 and the manifold 102 may be vertically connected, and one or more ink channels 104 may be provided in consideration of the supply speed of ink. have. The ink channel 104 may have various cross-sectional shapes, such as a circle or a polygon.

The ink chamber 106 is a space in which the ink to be discharged is filled, and is formed on the surface of the substrate 110 at a predetermined depth, for example, about 10 μm to 80 μm. In addition, the ink chamber 106 is preferably defined by sidewalls 112 surrounding the ink chamber 106. The sidewalls 112 may be formed to surround the ink chamber 106 in a quadrangular shape. In this case, the ink chamber 106 can be formed very accurately in the dimensions designed by the side walls 112. That is, the ink chamber 106 may have an optimal volume designed to improve the ejection performance of the ink droplets.

The sidewalls 112 may be formed of a material different from that of the substrate 110. This is to allow the sidewalls 112 to function as an etch stop in the process of forming the ink chamber 106 by isotropic etching of the substrate 110, as described below. Therefore, when the substrate 110 is made of a silicon wafer, the sidewalls 112 may be made of an insulating material such as silicon oxide. In this case, there is an advantage in that the side wall 112 and the first protective layer 121 described later can be simultaneously formed of the same material. Meanwhile, the sidewalls 112 may be made of a metal material. In this case, heat inside the ink chamber 106 may be discharged more quickly through the sidewalls 121.

As described above, the nozzle plate 120 is provided on the substrate 110 on which the ink chamber 106, the ink channel 104, and the manifold 102 are formed. The nozzle plate 120 forms an upper wall of the ink chamber 106. The nozzle plate 120 is formed by vertically penetrating a nozzle 108 through which ink is discharged from the ink chamber 106.

The nozzle plate 120 is composed of a plurality of material layers stacked on the substrate 110. The material layers comprise a plurality of passivation layers 121, 122, 123, 124, further comprising a heat dissipation layer 128, preferably made of metal, more preferably a heat conducting layer 125 126). In addition, between the protective layers 121, 122, 123, and 124, two pairs of heaters 131 and 132 and conductors 141 and 142 connected to each of the two pairs of heaters 131 and 132 are provided. .

The first passivation layer 121 is formed on the upper surface of the substrate 110 as the material layer at the bottom of the plurality of material layers constituting the nozzle plate 120. The first protective layer 121 is a material layer for protecting two pairs of heaters 131 and 132 formed thereon and insulation between the two pairs of heaters 131 and 132 and the substrate 110 thereunder. It may be formed by depositing silicon oxide or silicon nitride on the surface of the substrate 110.

Two pairs of heaters, that is, the first heater pair 131 and the second heater pair 132, which are positioned above the ink chamber 106 and heat the ink in the ink chamber 106 on the first protective layer 121. Is formed. The first heater pair 131 and the second heater pair 132 may both be formed in a rectangular shape having the same size. The first heater pair 131 and the second heater pair 132 are disposed to alternate with each other around the nozzle 108. That is, the two unit heaters constituting the first heater pair 131 are disposed on one diagonal of the ink chamber 106, and the two unit heaters constituting the second heater pair 132 are the ink chamber 106. Are placed on different diagonals.

The first heater pair 131 and the second heater pair 132 are driven independently of each other. Therefore, the first conductor 141 and the second conductor 142 are connected to the first heater pair 131 and the second heater pair 132, respectively. The first conductor 141 is connected in series to two unit heaters constituting the first heater pair 131, and the second conductor 142 is connected to two unit heaters constituting the second heater pair 132. Connected in series, a pulse current is applied to each of the first heater pair 131 and the second heater pair 132 independently. In order to achieve such a connection structure, the first conductor 141 and the second conductor 142 are divided into two layers so as to be insulated from each other, and a second protective layer 122 is interposed between the layers. This will be described later.

Since the first heater pair 131 and the second heater pair 132 may be driven independently, the first heater pair 131 and the second heater pair 132 may be driven alternately at every discharge or at regular time intervals, or may be simultaneously driven. When the first heater pair 131 and the second heater pair 132 are alternately driven, the life of the print head may be extended than in the conventional case of continuously using only one or a pair of heaters. In addition, when simultaneously driving the first heater pair 131 and the second heater pair 132, the number of bubbles generated increases, so that the same size as the bubbles smaller than the bubbles generated by one or a pair of heaters. The droplet of the volume can be discharged. As the size of the bubble is reduced in this way, the pressure applied to the heater at the time of disappearing of the bubble is reduced, and thus the cavitation damage of the heater is enjoyed, thereby extending the life of the printhead.

A second passivation layer 122 is formed on the first passivation layer 121, the first heater pair 131, and the second heater pair 132. Like the first passivation layer 121, the second passivation layer 122 may be made of silicon nitride or silicon oxide.

A portion of each of the first conductor 141 and the second conductor 142 is formed on the second protective layer 122, and a first heat conductive layer 125 is formed. The third passivation layer 123 is formed on the second passivation layer 122, and the remaining portions of the first conductor 141 and the second conductor 142 and the second heat conducting layer are formed on the third passivation layer 123. 126 is formed.

The first heat conductive layer 125 functions to conduct the first heater pair 131 and the second heater pair 132 and the heat around them to the substrate 110 and the heat dissipating layer 128 described later. The first thermal conductive layer 125 is in contact with the upper surface of the substrate 110 through a contact hole H formed through the first protective layer 121 and the second protective layer 122. The first thermoelectric layer 125 may be made of a metal having good conductivity, such as aluminum or an aluminum alloy, or gold or silver, together with the first conductor 141 and the second conductor 142.

In FIG. 6, as described above, the first conductor 141 and the second conductor 141 and the second conductor 141 formed on the lower layer of the first conductor 141 and the second conductor 142 are formed on the second protective layer 122. A portion of each of the conductors 142 is shown. In detail, the unit conductors 141a and 141b constituting the first conductor 141 and the unit conductors 142a and 142c constituting the second conductor 142 are formed on the second protective layer 122. The unit conductors 141a, 141b, 142a, and 142c are connected to ends of the first heater pair 131 and the second heater pair 132, respectively, via via holes C formed in the second passivation layer 122. .

In FIG. 7, the first conductor 141 and the second conductor 142 formed on the upper layer of the first conductor 141 and the second conductor 142, that is, formed on the third protective layer 123, are formed in two layers. Each remaining part is shown. Specifically, unit conductors 141c and 141d constituting the first conductor 141 and unit conductors 142b constituting the second conductor 142 are formed on the third passivation layer 123. The unit conductors 141c, 141d, and 142b are also connected to ends of the first heater pair 131 and the second heater pair 132 through via holes C formed in the third passivation layer 123, respectively.

As described above, the first conductor 141 and the second conductor 142 are divided into two layers, and thus, the first heater pair 131 and the second heater pair 132 are insulated from each other. Can be connected in series. Specifically, the first conductor 141 is connected to the three unit conductors (141a, 141b, 141c) in order to supply current to the unit heaters of the first heater pair 131 in the direction as shown in FIG. In the second conductor 142, four unit conductors 142a, 142b, 142c, and 142b are sequentially connected to the unit heaters of the second heater pair 132 in the direction as shown in FIG. 4. Current can be supplied.

Meanwhile, the arrangement of the first conductor 141 and the second conductor 142 is merely exemplary, and may be variously changed according to the arrangement of the first heater pair 131 and the second heater pair 132. Can be.

The second thermal conductive layer 126 has the same function as the first thermal conductive layer 125 and may be made of the same material. The second thermal conductive layer 126 is in contact with the upper surface of the first protective layer 125 through the contact hole H formed in the third protective layer 123.

A fourth passivation layer 124 is formed on the third passivation layer 123, the first conductor 141, the second conductor 142, and the second heat conductive layer 126. The fourth protective layer 124 is for insulation between the heat dissipation layer 128 formed thereon and the first and second conductors 141 and 142 thereunder, and is a tetraethylorthosilicate (TEOS) oxide, silicon oxide or It may be made of silicon nitride.

The heat dissipation layer 128 is formed on the fourth passivation layer 124 and is in contact with the second heat conductive layer 126 through the contact hole H. Therefore, the heat dissipation layer 128 is in thermal contact with the upper surface of the substrate 110 through the second and first heat conductive layers 126 and 125. The heat dissipation layer 128 is made of a metal material having good thermal conductivity, such as nickel, copper, aluminum, or gold. The heat dissipation layer 128 may be formed of one metal layer or a plurality of metal layers. The heat dissipation layer 128 may be formed to a relatively thick thickness of about 10 ~ 100㎛ by electroplating the metal material on the fourth protective layer 124. To this end, a seed layer 127 for electroplating the metal material may be provided on the fourth passivation layer 124. The seed layer 127 is made of a metal material having good conductivity such as copper, chromium, titanium, gold, or nickel.

As described above, since the heat dissipation layer 128 made of metal is formed by a plating process, the heat dissipation layer 128 may be formed integrally with other components of the inkjet printhead, and may be formed with a relatively thick thickness, so that effective heat dissipation may be achieved. Can be done.

The heat dissipation layer 128 functions to dissipate the pair of heaters 131 and 132 and the heat around them to the outside. Therefore, after the ink is discharged, the heat remaining in the two pairs of heaters 131 and 132 and the periphery thereof is conducted to the substrate 110 through the heat conducting layers 125 and 126 and the heat dissipating layer 128, or externally. Is divergent. As such, when the heat conductive layers 125 and 126 and the heat dissipation layer 128 are provided, faster heat dissipation can be achieved after the ink is discharged, so that stable printing can be performed at a higher driving frequency.

In addition, as described above, since the heat dissipation layer 128 may be formed to have a relatively thick thickness, the length of the nozzle 108 may be sufficiently long. Therefore, stable high speed printing is enabled, and the straightness of the ink droplets discharged through the nozzle 108 is improved. That is, the ejected ink droplet may be ejected in a direction that is exactly perpendicular to the substrate 110.

The nozzle 108 is formed through the nozzle plate 120. It is preferable that the nozzle 108 has a tapered shape in which the cross-sectional area decreases toward the outlet as shown. In this way, when the shape of the nozzle 108 is tapered, there is an advantage that the meniscus on the surface of the ink is stabilized more quickly after ejecting the ink.

8 is a plan view illustrating a modification of the two pairs of heaters shown in FIG. 4.

Referring to FIG. 8, the first heater pair 231 and the second heater pair 232 may be formed in different sizes. Therefore, when the first heater pair 231 and the second heater pair 232 are used in combination, it is possible to discharge droplets having different volumes from the same nozzle 108. In detail, when only the first heater pair 231 having a smaller size is driven, a small bubble may be formed to discharge the droplet having the smallest volume, and only the second heater pair 232 having a larger size may be discharged. In the case of driving, a large bubble is formed to eject a droplet having a large volume. When the first heater pair 231 and the second heater pair 232 are simultaneously driven, small bubbles and large bubbles are formed at the same time, so that droplets having the largest volume can be discharged.

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

9 to 21 are cross-sectional views for explaining step-by-step a preferred method for manufacturing the integrated inkjet printhead according to the present invention.

First, referring to FIG. 9, in the present embodiment, a silicon wafer is processed to a thickness of about 300 to 700 μm as the substrate 110. Silicon wafers are widely used in the manufacture of semiconductor devices and are effective for mass production.

On the other hand, as shown in Figure 9 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.

An etching mask 114 is formed on the upper surface of the prepared silicon substrate 110 to define a portion to be etched. The etching mask 114 may be formed by applying a photoresist on a top surface of the substrate 110 to a predetermined thickness and then patterning the photoresist.

Subsequently, the substrate 110 exposed through the etching mask 114 is etched to form the trench 111 having a predetermined depth. The substrate 110 may be etched by a dry etching method such as reactive ion etching (RIE). The depth of the trench 111 is determined in the order of several tens of micrometers in consideration of the depth of the ink chamber (106 in FIG. 20) to be formed in the step of Figure 20, the width of the trench 111 is easy to a predetermined material therein It is formed to a few micrometers so that it can be filled. In addition, the trench 111 is formed in a shape that encloses a portion where the ink chamber 106 is to be formed in a rectangle. Meanwhile, the trench 111 may be formed in various shapes according to the planar shape design of the ink chamber 106, and thus, the ink chamber 106 having a desired size and shape, for example, a rectangular planar shape may be accurately obtained. have. After forming the trench 111, the etching mask 114 on the substrate 110 is removed.

Subsequently, as shown in FIG. 10, a predetermined material is deposited on the surface of the substrate 110 on which the trench 111 is formed. Accordingly, the material is filled in the trench 111 to form sidewalls 112. As the material, a material different from the substrate 110 is used. This is to allow the sidewall 112 to function as an etch stop when the silicon substrate 110 is etched to form the ink chamber 106 in the step of FIG. 20. Therefore, when the substrate 110 is made of silicon, an insulating material or a metal material such as, for example, silicon oxide or silicon nitride may be used as the material.

FIG. 11 illustrates a state in which a first protective layer 121 and two pairs of heaters 131 and 132 are formed on an upper surface of the substrate 110.

Specifically, the first protective layer 121 may be formed by depositing silicon oxide or silicon nitride on the upper surface of the substrate 110.

Next, two pairs of heaters 131 and 132 are formed on the first protective layer 121 formed on the upper surface of the substrate 110. The two pairs of heaters 131 and 132 may include polysilicon, tantalum-aluminum, tantalum nitride, titanium nitride, or tungsten silicide doped with impurities on the entire surface of the first protective layer 121. It can be formed by depositing a resistive heating element such as tungsten silicide (Tungsten silicide) to a predetermined thickness, and then patterning it to the shape shown in FIG. 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 approximately 0.1-0.3 μm by sputtering or chemical vapor deposition (CVD). 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. 12, the second protective layer 122 is formed on the upper surfaces of the first protective layer 121 and the two pairs of heaters 131 and 132. Specifically, the second protective layer 122 may be formed by depositing silicon oxide or silicon nitride to a thickness of about 0.5 μm. Subsequently, the second protective layer 122 is partially etched, so that a portion of each of the two pairs of heaters 131 and 132 illustrated in FIG. 6, that is, a portion to be connected to each of the first and second conductors 141 and 142 is illustrated. Forming a plurality of via holes C exposing the plurality of via holes, and sequentially etching the second protective layer 122 and the first protective layer 121 to contact a portion of the substrate 110, that is, the first thermal conductive layer 125. The contact hole H exposing the portion to be formed is formed. The via hole C and the contact hole H may be formed at the same time.

FIG. 13 is a view illustrating a state in which portions of the first and second conductors 141 and 142 and the first thermal conductive layer 125 are formed on the upper surface of the second protective layer 122. Specifically, the portions of the first and second conductors 141 and 142 and the first thermal conductive layer 125 are approximately 1 μm thick by sputtering a metal having good electrical and thermal conductivity, such as aluminum or an aluminum alloy or gold or silver. It can be formed simultaneously by depositing and patterning it. In this case, the first and second conductors 141 and 142 and the first thermal conductive layer 125 are patterned to be insulated from each other. Then, the first and second conductors 141 and 142 are connected to the two pairs of heaters 131 and 132, respectively, and the first thermal conductive layer 125 is in contact with the substrate 110 through the contact hole H. .

FIG. 14 illustrates a third protective layer 123 on the entire surface of the resultant product of FIG. 13, the remaining portions of the first and second conductors 141 and 142 and the second thermal conductive layer 126 and the fourth protective layer shown in FIG. 7. It is a figure which shows the state which formed 124 sequentially. Specifically, in detail, the third protective layer 123 may be formed in the same manner as the second protective layer 122, and the remaining portions of the first and second conductors 141 and 142 and the second thermal conductive layer ( 126 may also be formed in the same manner as described in FIG. The fourth protective layer 124 may be formed by depositing TEOS (Tetraethylorthosilicate) oxide to a thickness of about 0.7 to 3 μm by plasma enhanced chemical vapor deposition (PECVD). Subsequently, the fourth protective layer 124 is partially etched to partially expose the second thermal conductive layer 126.

15 illustrates a state in which the lower portion of the nozzle 108 is formed. The lower portion of the nozzle 108 may be formed by sequentially etching the fourth, third, second, and first protective layers 124, 123, 122, and 121 by reactive ion etching (RIE). Can be. At this time, a portion of the upper surface of the substrate 110 is exposed through the nozzle 108.

Next, as shown in FIG. 16, the sacrificial layer S is formed inside the nozzle 108. Specifically, after the photoresist is applied to the resultant entire surface of FIG. 15, the photoresist is patterned to leave only the photoresist filled inside the nozzle 108. The remaining photoresist forms the sacrificial layer S and maintains the shape of the nozzle 109 in a subsequent process. Subsequently, a seed layer 127 for electroplating is formed on the entire surface of the resultant product. The seed layer 127 is formed by sputtering a metal such as copper (Cu), chromium (Cr), titanium (Ti), gold (Au), or nickel (Ni) having good conductivity for electroplating. It can be done by depositing at a thickness.

FIG. 17 illustrates a state in which a plating mold P for forming an upper portion of the nozzle 108 is formed. Specifically, the plating mold P may be formed by applying a photoresist on the entire surface of the seed layer 127 to a predetermined thickness and then patterning the photoresist into the shape of the nozzle 108. On the other hand, the plating mold (P) may be made of a photosensitive polymer as well as a photoresist. Specifically, photoresist is applied to the entire surface of the seed layer 127 to a thickness slightly higher than the height of the nozzle 108. The photoresist is then patterned, leaving only the portion where the nozzle 108 is to be formed. At this time, the photoresist is patterned into a tapered shape in which its cross-sectional area gradually widens from the top to the bottom. Such patterning may be performed by proximity exposure exposing the photoresist through a photomask provided spaced a predetermined distance from the upper surface of the photoresist. In this case, the light passing through the photomask is diffracted, whereby the interface between the exposed portion of the photoresist and the unexposed portion is inclined. The slope and the exposure depth of the interface may be controlled by the exposure energy and the distance between the photomask and the photoresist in the proximity exposure process. On the other hand, the nozzle 108 may be formed in a columnar shape, in which case the photoresist is patterned into a columnar shape.

Next, as shown in FIG. 18, a heat dissipation layer 128 made of a metal material having a predetermined thickness is formed on the top surface of the seed layer 127. The heat dissipation layer 128 is approximately 10 to 100 μm thick by electroplating a good thermal conductivity metal, such as nickel (Ni), copper (Cu), aluminum (Al), or gold (Au), on the seed layer 127 surface. It can be formed as. In this case, the heat dissipation layer 128 may be formed of a plurality of metal layers.

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

Subsequently, the plating mold P is removed, and the seed layer 127 and the sacrificial layer S of the exposed portions are removed by removing the plating mold P. The plating mold P can be removed by, for example, acetone by a conventional method of removing photoresist. The seed layer 127 may be formed by using an etchant capable of selectively etching only the seed layer 127 in consideration of the etching selectivity between the metal material constituting the heat dissipation layer 128 and the metal material constituting the seed layer 127. It may be etched by wet etching. For example, when the seed layer 127 is made of copper (Cu), it may be made of acetic acid-based etchant, and if it is made of titanium (Ti), an HF base etchant may be used.

Then, a complete nozzle 108 is formed as shown in FIG. 19, and a nozzle plate 120 formed by stacking a plurality of material layers is completed.

20 illustrates a state in which the ink chamber 106 is formed on the surface side of the substrate 110. The ink chamber 106 may be formed by isotropic etching of the substrate 110 exposed by the nozzle 108. Specifically, the substrate 110 is dry-etched for a predetermined time using XeF ₂ gas or BrF ₃ gas as an etching gas. At this time, since the etching of the substrate 110 is performed by isotropic etching, the substrate 110 is etched at the same speed in all directions from the portion exposed by the nozzle 108. However, in the sidewall 112 serving as an etch stop, the etching in the horizontal direction is blocked, so only the etching in the vertical direction proceeds. Thus, an ink chamber 106 having a rectangular shape surrounded by the side wall 112 is formed as shown.

FIG. 21 illustrates a state in which the manifold 102 and the ink channel 104 are formed by etching the rear surface of the substrate 110. Specifically, after forming an etching mask defining a region to be etched on the back of the substrate 110, using the back surface of the substrate 110 using TMAH (Tetramethyl Ammonium Hydroxide) or potassium hydroxide (KOH) as an etching solution Wet etching results in a manifold 102 with inclined sides as shown. Meanwhile, the manifold 102 may be formed by anisotropic dry etching the back surface of the substrate 110. Subsequently, after forming an etching mask defining the ink channel 104 on the back surface of the substrate 110 on which the manifold 102 is formed, the substrate 110 between the manifold 102 and the ink chamber 106 is reactive. The ink channel 104 is formed by anisotropic dry etching by ion etching (RIE). In this case, the ink channel 104 may be formed in a circular or polygonal shape, or may be formed in plural as described above.

After the above steps, the integrated inkjet printhead according to the present invention is completed as shown in FIG.

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. That is, the substrate is not necessarily silicon but may be replaced with other materials having good processability. The same applies to the sidewalls, the heaters, the conductors, the protective layers, the heat conductive layers, and the heat dissipating layers. In addition, the method of laminating and forming each material is also merely illustrated, and various deposition methods and etching methods may be applied. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

As described above, the integrated inkjet printhead according to the present invention has the following effects.

First, since two pairs of heaters are independently driven on both sides of the nozzle, the two pairs of heaters can be used alternately, so the life of the printhead is longer than in the conventional case of continuously using only one or a pair of heaters. Can be extended.

Second, when two pairs of heaters are used at the same time, it is possible to discharge the same volume of droplets as bubbles of a smaller size than the bubbles generated by one or a pair of heaters. Therefore, the pressure applied to the heater at the time of dissipation of the bubble is reduced, so that the cavitation damage of the heater is enjoyed, thereby extending the life of the printhead.

Third, when two pairs of heaters having different sizes are used in combination, it is possible to discharge droplets having three different volumes from the same nozzle, thereby improving print quality.

Fourth, heat dissipation capability can be further improved by the heat dissipation layer made of a metal having a thick thickness. Further, the length of the nozzle can be secured sufficiently long, so that the meniscus can be maintained in the nozzle, so that stable ink refilling is possible, and the straightness of the ejected ink droplets can be improved.

1A and 1B are diagrams illustrating an example of a conventional thermal drive inkjet printhead, and FIG. 1A is a partially cutaway perspective view, and FIG. 2B is a cross-sectional view for explaining an ink droplet ejection process.

2A and 2B are diagrams showing an example of a conventional integrated inkjet printhead, FIG. 2A is a plan view, and FIG. 2B is a vertical sectional view taken along the line AA ′ of FIG. 2A.

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

FIG. 4 is a plan view of an integrated inkjet printhead according to a preferred embodiment of the present invention, in which the portion B of FIG. 3 is enlarged, showing a layout structure of two pairs of heaters and a conductor.

5 is a vertical cross-sectional view of the integrated inkjet printhead according to the preferred embodiment of the present invention along the line X-X 'shown in FIG.

6 and 7 are plan views showing arrangements of conductors connected to the two pairs of heaters shown in FIG. 4, FIG. 6 is a view showing conductors formed on a lower layer, and FIG. 7 is a view showing conductors formed on an upper layer. .

8 is a plan view illustrating a modification of the two pairs of heaters shown in FIG. 4.

9 to 21 are cross-sectional views for explaining step-by-step a preferred method for manufacturing the integrated inkjet printhead according to the present invention.

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

102 Manifold 104 Ink channel

106 ... ink chamber 108 ... nozzle

110 Silicon substrate 112 Side wall

120 Nozzle plate 121 First protective layer

122 ... second protective layer 123 ... third protective layer

124 ... fourth protective layer 125 ... first heat transfer layer

126 second heat transfer layer 127 seed layer

128 Heat dissipation layer 131,231 First heater pair

132,232 ... 2nd heater pair 141 ... 1st conductor

142.Second conductor

Claims (36)

A substrate having an ink chamber filled with ink to be discharged, a manifold for supplying ink to the ink chamber, and an ink channel connecting the ink chamber and the manifold; A nozzle plate formed of a plurality of material layers stacked on the substrate and formed by penetrating a nozzle connected to the ink chamber; A first heater pair and a second heater pair provided inside the nozzle plate so as to be positioned above the ink chamber and driven independently of each other and disposed around the nozzle; And A first conductor and a second conductor provided inside the nozzle plate and connected to the first heater pair and the second heater pair, respectively, for supplying current to the first heater pair and the second heater pair, respectively; An integrated inkjet printhead, characterized in that. The method of claim 1, And the first heater pair and the second heater pair are arranged alternately around the nozzle. The method of claim 2, Two unit heaters constituting the first heater pair are disposed on one diagonal of the ink chamber, and two unit heaters constituting the second heater pair are disposed on another diagonal of the ink chamber. Integrated inkjet printhead. The method according to any one of claims 1 to 3, Two unit heaters constituting the first heater pair are connected in series to the first conductor, and two unit heaters constituting the second heater pair are connected in series with the second conductor. head. The method of claim 4, wherein Wherein the unit conductors constituting the first conductor and the unit conductors constituting the second conductor are disposed in two layers. The method of claim 5, The plurality of material layers constituting the nozzle plate may include first, second, third and fourth protective layers, The first heater pair and the second heater pair are formed on the first passivation layer, some of the unit conductors are disposed on the second passivation layer, and other portions of the unit conductors are on the third passivation layer. An integrated inkjet printhead, wherein the inkjet printhead is disposed. The method according to any one of claims 1 to 3, And the first heater pair and the second heater pair have the same size. The method according to any one of claims 1 to 3, The inkjet printhead of claim 1, wherein the first heater pair and the second heater pair have different sizes. The method of claim 1, And the ink chamber is surrounded by sidewalls formed to a predetermined depth from the surface of the substrate. The method of claim 9, And the sidewalls surround the ink chamber in a quadrangular shape. The method of claim 1, And the nozzle plate includes a plurality of protective layers stacked on the substrate, and a heat dissipation layer formed on the protective layer and made of a thermally conductive metal material. The method of claim 11, And a heat conductive layer insulated from the first and second heater pairs and the first and second conductors and in contact with the substrate and the heat dissipating layer between the plurality of protective layers. The method of claim 12, And the first and second conductors and the thermal conductive layer are made of the same metal material. The method of claim 12, The protective layers include first, second, third and fourth protective layers, The first heater pair and the second heater pair are formed on the first passivation layer, a portion of the first and second conductors and a first heat conductive layer are disposed on the second passivation layer, and the first passivation layer is disposed on the third passivation layer. And the remaining portion of the first and second conductors and the second thermal conductive layer are disposed. The method of claim 11, And the heat dissipating layer is in thermal contact with the surface of the substrate through contact holes formed in the passivation layers. The method of claim 11, The heat dissipation layer is an integral inkjet printhead, characterized in that formed by electroplating. The method of claim 16, And a seed layer for electroplating the heat dissipating layer on the passivation layers. The method of claim 1, And the nozzle has a tapered shape in which the cross-sectional area decreases toward the outlet. (A) preparing a substrate; (B) forming sidewalls of a material different from a material forming the substrate in the substrate; (C) integrally forming a nozzle plate on the substrate, the nozzle plate consisting of a plurality of stacked material layers and having nozzles therethrough, disposed around the nozzles between the material layers and driven independently of one another; A first conductor and a second conductor connected to the first heater pair and the second heater pair and the first heater pair and the second heater pair respectively to supply current to the first heater pair and the second heater pair, respectively. Forming; (D) isotropically etching the substrate exposed through the nozzle while using the sidewall as an etch stop wall to form an ink chamber defined by the sidewall; (E) forming a manifold for supplying ink by etching the rear surface of the substrate; And (F) forming an ink channel by etching through the substrate between the manifold and the ink chamber to form an ink channel. The method of claim 19, In the step (a), wherein the substrate is a silicon wafer, characterized in that the manufacturing method of the inkjet printhead. The method of claim 19, wherein step (b) comprises: Forming an etching mask defining a portion to be etched on an upper surface of the substrate; Etching the substrate exposed through the etching mask to a predetermined depth to form a trench; Removing the etch mask; And And depositing a material different from the material forming the substrate on the surface of the substrate to fill the trench to form the sidewalls. The method of claim 21, And the material forming the sidewalls is any one of silicon oxide, silicon nitride, and a metal material. The method of claim 19, In the step (c), the first heater pair and the second heater pair are disposed so as to alternate with each other around the nozzle. The method of claim 19, In the step (c), the first conductor is arranged to connect two unit heaters constituting the first heater pair in series, and the second conductor connects two unit heaters constituting the second heater pair in series. A method of manufacturing an integrated inkjet printhead, characterized in that it is arranged to connect. 25. The method of any of claims 19, 23 and 24, wherein step (c) comprises: (C-1) sequentially stacking a plurality of protective layers on the substrate, and forming the first heater pair and the second heater pair and the first conductor and the second conductor between the protective layers; And (C-2) forming the heat dissipation layer made of a metal on the protective layers, and forming the nozzle to pass through the protective layers and the heat dissipation layer; Method of preparation. The method of claim 25, wherein the step (c) -1 comprises: Forming a first protective layer on an upper surface of the substrate; Forming the first heater pair and the second heater pair on the first passivation layer; Forming a second passivation layer on the first passivation layer; Forming a portion of the first conductor and the second conductor on the second protective layer; Forming a third passivation layer on the second passivation layer; Forming remaining portions of the first conductor and the second conductor on the third protective layer; And Forming a fourth passivation layer on the third passivation layer. The method of claim 26, A heat conductive layer insulated from the first and second heater pairs and the first and second conductors and in contact with the substrate and the heat dissipating layer is formed on the second protective layer and the third protective layer. Method for producing an inkjet printhead. The method of claim 27, And the thermal conductive layer is formed of the same metal material as the first and second conductors. The method of claim 25, In the step (c-2), the heat dissipation layer is a method of manufacturing an integrated inkjet printhead, characterized in that made of any one metal of nickel, copper, aluminum, and gold. The method of claim 25, In the step (c-2), the heat dissipation layer is a method of manufacturing an integrated inkjet printhead, characterized in that formed by 10 to 100㎛ thickness by electroplating. The method of claim 25, wherein the (c-2) step, Forming a lower portion of the nozzle by etching the protective layers to a predetermined diameter on an upper portion of the portion where the ink chamber is to be formed; Forming a sacrificial layer inside the nozzle; Forming a seed layer for electroplating the heat dissipating layer on the sacrificial layer and the protective layer; Forming a plating mold for forming an upper portion of the nozzle on the seed layer; Forming the heat dissipating layer on the seed layer by electroplating; And And removing the plating mold, the seed layer under the plating mold, and the sacrificial layer to form the nozzles. The method of claim 31, wherein And the sacrificial layer and the plating mold are made of photoresist or photosensitive polymer. The method of claim 31, wherein The plating mold is a method of manufacturing an integrated inkjet printhead, characterized in that formed in a tapered shape whose cross-sectional area is gradually narrowed upwards. The method of claim 31, wherein And after the forming of the heat dissipating layer, planarizing the top surface of the heat dissipating layer by a chemical mechanical polishing process. The method of claim 19, In the step (d), in the vicinity of the side wall, the etching in the horizontal direction is inhibited by the side wall, and only the etching in the vertical direction is performed. The method of claim 19, In the step (bar), the substrate is dry-etched from the back side of the substrate on which the manifold is formed by reactive ion etching to form the ink channel.