KR20050067995A - Inkjet printhead and method for manufacturing the same - Google Patents

Abstract

An inkjet printhead and a method of manufacturing the same are disclosed. The disclosed inkjet printhead includes a substrate having a heater layer and a conductive layer formed thereon; A planarization layer formed to protrude on the substrate and planarizing an upper surface of the heater layer formed on the upper portion and the conducting layer formed on both sides thereof; A protective layer formed on upper surfaces of the heater layer and the conductive layer; A chamber layer laminated on top of the protective layer to define an ink chamber; And a nozzle plate stacked on the chamber layer and having a nozzle formed thereon.

Description

Inkjet printheads and method for manufacturing the same

The present invention relates to an inkjet printhead and a method for manufacturing the same, and more particularly, to an inkjet printhead and a method for manufacturing the same, which can increase the lifespan and reliability of the heater layer by planarizing an upper portion of the heater layer.

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 the ink droplets by the expansion force of the bubbles, and the other is ink due to the deformation of the piezoelectric body using the piezoelectric body. A piezoelectric drive inkjet printhead which discharges ink droplets by a pressure applied thereto.

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

On the other hand, such a thermal driving method is a top-shooting method, a side-shooting method and a back-shooting method again according to the bubble growth direction and the ink droplet ejection direction. Are classified. In the top-shooting method, the bubble growth direction and the ink droplet ejection direction are the same. In the side-shooting method, the bubble growth direction and the ink droplet ejection direction are perpendicular to each other. The back-shooting method is the bubble growth. The ink ejection method in which the direction and the ejection direction of 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 the 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.

1 is a cross-sectional view schematically showing a conventional top-shooting inkjet printhead.

Referring to FIG. 1, an inkjet printhead includes a substrate 11 having a plurality of material layers stacked thereon, a chamber layer 20 stacked on the substrate 11 to define an ink chamber 22, and the chamber. It consists of a nozzle plate 30 that is stacked over the layer 20. Ink is filled in the ink chamber 22, and a heater layer 13 is provided below the ink chamber 22 to generate bubbles by heating the ink. The nozzle plate 30 is provided with a nozzle 32 through which ink is ejected.

The vertical structure of the inkjet printhead will be described in more detail. On the substrate 11 made of silicon, an insulating layer 12 for insulating and insulating between the heater layer 13 and the substrate 11 is formed. The heater layer 13 is formed on the insulating layer 12 to generate bubbles by heating the ink in the ink chamber 22. The heater layer 13 is formed by depositing tantalum nitride (TaN) or tantalum-aluminum alloy (TaAl) or the like on the insulating layer 12 in the form of a thin film. A conductor layer 14 for applying a current to the heater layer 13 is formed on the heater layer 13. The wire layer 14 is made of a metal material having good conductivity such as aluminum (Al).

A passivation layer 15 is formed on the heater layer 13 and the conductive layer 14 to protect them. The protective layer 15 is for preventing the heater layer 13 and the conductive layer 14 from being oxidized or in direct contact with the ink. The protective layer 15 is mainly formed by depositing a silicon nitride film (SiN _x ). In addition, an anti-cavitation layer 16 is formed on the protective layer 15. This cavitation prevention layer 16 is for protecting the heater layer 13 from the cavitation pressure generated when the bubbles disappear, and mainly consists of tantalum (Ta).

Meanwhile, the chamber layer 20 defining the ink chamber 22 is formed on the substrate 11 on which several material layers are stacked. And the nozzle plate 30 in which the nozzle 32 is formed on this chamber layer 20 is formed.

In the inkjet printhead having the above structure, the conductive layer 14 deposits a metal material such as aluminum on the upper surface of the heater layer 13, and a portion of the heater layer 13 is wet etched. It is formed by patterning to expose. As a result, a step is present in the upper portion of the heater layer 13 by the thickness of the conductive layer 14. Here, the thickness of the conductive layer is about 1 μm. Due to the presence of the step, a coverage problem occurs when the protective layer 15 and the cavitation prevention layer 16 are coated. In FIG. 2, the protective layer 15 and the cavitation prevention layer 16 formed thereon are not planarized due to the step existing on the heater layer 13.

On the other hand, the resistance of the heating portion of the heater layer 13 is determined by the region of the heater layer 13 exposed by the conductive layer 14, the exposed region of the heater layer 13 is large by the wet etching process. get affected. However, since the wet etching is highly dependent on process variables such as an etch solution, the reproducibility of the process is insufficient.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an inkjet printhead and a method of manufacturing the same, which can increase the lifespan and reliability of the heater layer by planarizing the top of the heater layer.

In order to achieve the above object,

The inkjet printhead according to the present invention,

A substrate having a heater layer formed thereon and a conductor layer for applying current to the heater layer;

A planarization layer formed to protrude on the substrate to planarize an upper surface of the heater layer formed on the substrate and the conductive layer formed on both sides of the heater layer;

A protective layer formed on upper surfaces of the heater layer and the conductive layer;

A chamber layer defining an ink chamber stacked on top of the protective layer and filled with ink to be discharged; And

And a nozzle plate stacked on the chamber layer and having nozzles through which ink is discharged.

Here, the thickness of the planarization layer and the thickness of the conductive layer are preferably the same. The planarization layer may be formed of silicon oxide.

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

Forming an insulating layer on an upper surface of the substrate;

Forming a material layer on an upper surface of the insulating layer and patterning the material layer to form a planarization layer;

Forming a heater layer on upper surfaces of the insulating layer and the planarization layer;

Forming a conductive layer on both sides of the planarization layer so as to be flat with the heater layer positioned above the planarization layer;

Forming a protective layer on upper surfaces of the heater layer and the conductive layer;

Forming a chamber layer defining an ink chamber on top of the protective layer; And

And forming a nozzle plate having a nozzle formed on an upper surface of the chamber layer.

Here, the conductive layer is preferably formed to the same thickness as the planarization layer.

Forming the conductive layer,

Forming a predetermined metal layer on an upper surface of the heater layer;

Providing an etching mask exposing the metal layer on the planarization layer;

Wet etching the metal layer exposed through the etching mask to expose the heater layer on the planarization layer; And

Soft etching to remove the metal layer remaining protruding in the edge portion of the exposed heater layer; preferably.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments exemplified below are not intended to limit the scope of the present invention, but are provided to explain the present invention to those skilled in the art. The same reference numerals in the drawings refer to the same components, the size or thickness of each component in the drawings may be exaggerated for convenience of explanation. Also, when one layer is described as being on top of a substrate or another layer, the layer may be on top while directly contacting the substrate or another layer, and another third layer may be present therebetween.

3 is a vertical sectional view schematically showing a top-shooting inkjet printhead according to a preferred embodiment of the present invention.

Referring to FIG. 3, an insulating layer 112 for insulating and insulating between the heater layer 113 and the substrate 111 is formed on a surface of the substrate 111 made of silicon. The planarization layer 150 protrudes from the insulating layer 112. The planarization layer 150 is a layer provided to planarize the upper surface of the heater layer 113 formed on the upper surface and the upper surface of the conductive layer 114 formed on both sides thereof. The planarization layer 150 is formed on the top surface of the insulating layer 112 by silicon enhanced chemical vapor deposition (PECVD) or thermal oxidation (CVD) method of silicon oxide (SiO _x ), It is formed by patterning it into a predetermined shape.

Heater layers 113 for heating the ink in the ink chamber 122 are formed on the surfaces of the insulating layer 112 and the planarization layer 150. The heater layer 113 is formed by depositing tantalum nitride (TaN) or a tantalum-aluminum alloy or the like on the surfaces of the insulating layer 112 and the planarization layer 150 in the form of a thin film and patterning the same in a predetermined form. In addition, conductive layers 114 for applying a current to the heater layer 113 are formed at both sides of the planarization layer 150. Here, the conductive layer 114 is formed such that its upper surface is flat with the upper surface of the heater layer 113 positioned on the planarization layer 150. The conductive layer 114 is made of a metal material having good conductivity such as aluminum (Al).

A passivation layer 115 is formed on the planarized heater layer 113 and the conductive layer 114 to protect the heater layer 113 and the passivation layer 114. The protective layer 115 is for preventing the heater layer 113 and the conductive layer 114 from being oxidized or in direct contact with the ink, and is mainly formed by depositing a silicon nitride film (SiN _x ). An anti-cavitation layer 116 is formed on the passivation layer 115. The cavitation prevention layer 116 is for protecting the heater layer 113 from the cavitation pressure generated when the bubbles disappear, and is mainly made of tantalum (Ta).

Meanwhile, a chamber layer 120 is formed on the cavitation prevention layer 116 to define an ink chamber 122 filled with ink to be discharged. And the nozzle plate 130 in which the nozzle 132 which discharges ink from the ink chamber 122 is formed on this chamber layer 120. As shown in FIG.

Hereinafter, a method of manufacturing an inkjet printhead according to an embodiment of the present invention will be described with reference to FIGS. 4A to 4J.

FIG. 4A illustrates a state in which an insulating layer 112 is formed on an upper surface of the substrate 111 and a predetermined material layer 150 ′ is formed thereon. First, a silicon wafer is processed to a thickness of approximately 400 to 650 µm as the substrate 111. This is because silicon wafers are widely used in semiconductor devices and are effective for mass production.

Subsequently, an insulating layer 112 is formed on the prepared upper surface of the silicon substrate 111. The insulating layer 112 may be formed by depositing silicon oxide (SiO ₂ ) on the top surface of the substrate 111. The insulating layer 112 functions as a heat insulating layer for suppressing not only the insulation between the substrate 111 and the heater layer 113 but also the heat energy generated from the heater layer 113 to escape to the substrate 111.

Next, a predetermined material layer 150 ′ is formed on the upper surface of the insulating layer 112. Here, the material layer 150 ′ is formed by depositing silicon oxide (SiO _x ) on the upper surface of the insulating layer 112 by plasma enhanced chemical vapor deposition (PECVD) or thermal oxidization.

4B illustrates a state in which the planarization layer 150 is formed on the upper surface of the insulating layer 112. The planarization layer 150 is formed to protrude on the top surface of the insulating layer 112 by patterning the material layer 150 ′ shown in FIG. 4A in a predetermined shape. The material layer 150 ′ may be patterned by a wet etching method or a dry etching method. Here, the planarization layer 150 is formed to have the same thickness as the conductive layer 114, which will be described later, and is preferably formed to have a thickness of about 2000 m 2 to 2 m.

FIG. 4C illustrates a state in which the heater layer 113 is formed on the top surface of the insulating layer 112 and the planarization layer 150. The heater layer 113 generates heat such as tantalum nitride (TaN), tantalum-aluminum alloy (TaAl), titanium nitride (TiN), or tungsten silicide on the top surface of the insulating layer 112 and the planarization layer 150. It can be formed by depositing a resistor to a predetermined thickness and patterning it.

4D illustrates a state in which a predetermined metal layer 114 ′ is formed on the top surface of the heater layer 113. The metal layer 114 ′ may be formed by depositing a metal having good conductivity, such as aluminum (Al), on the top surface of the heater layer 113 to the same thickness as the planarization layer 150.

Subsequently, as shown in FIG. 4E, an etch mask 160 is formed on the top surface of the metal layer 114 ′ to expose the metal layer 114 ′ positioned above the planarization layer 150. The etching mask 160 may be formed by applying a photoresist (PR) on an upper surface of the metal layer 114 ′ and patterning the photoresist through a photolithography process.

Next, as shown in FIG. 4F, the metal layer 114 ′ exposed through the etching mask 160 is wet-etched. Accordingly, the heater layer 113 positioned on the planarization layer 150 is exposed. As shown in FIG. 4G, when the etching mask 160 is removed, the protruding metal layer 114a remains at the edge portion of the exposed heater layer 113.

Subsequently, when the protruding metal layer 114a is etched by a soft etch method, the protruding metal layer 114a is preferentially etched because the protruded metal layer 114a has a higher energy than other metal layer 114 '. Removed. As a result, as shown in FIG. 4H, the upper surface of the heater layer 113 exposed on both sides of the planarization layer 150 and the flat conductive layer 114 are formed.

4I illustrates a state in which a passivation layer 115 is formed on the planarized heater layer 113 and the conductive layer 114, and an anti-cavitation layer 116 is formed thereon. will be. The protective layer 115 may be formed by depositing silicon nitride (SiN ₄ ) on the top surface of the heater layer 113 and the conductive layer 114 by plasma enhanced chemical vapor deposition (PECVD). The protective layer 115 is to prevent the heater 113 and the conductive wire 114 from being oxidized or integrated contact with the ink. The cavitation prevention layer 116 may be formed by depositing tantalum (Ta) on the upper surface of the protective layer 115, and patterning the tantalum (Ta) to remain only on the heater layer. The cavitation prevention layer 116 is for preventing the heater layer 113 from being damaged by the high pressure generated when the bubbles in the ink chamber 122 shrink and disappear.

  4H illustrates a state in which a chamber layer 120 defining an ink chamber 122 and a nozzle plate 130 having a nozzle 132 formed on an upper surface of the chamber layer 120 are formed on the cavitation prevention layer 116. It is shown. The chamber layer 120 and the nozzle plate 130 are sequentially formed by a monolithic method.

Although the preferred embodiment according to the present invention has been described above, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

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

First, by flattening the upper portion of the heater layer, the life and reliability of the printhead can be improved.

Second, since the step coverage problem of the protective layer formed on the heater layer is solved, the thickness of the protective layer can be minimized, thereby improving the efficiency of the heater layer.

Third, when the planarization layer is formed by the dry etching method, the resistance of the heater layer with high reproducibility and reliability can be maintained.

Fourth, there is an effect of increasing productivity and reducing the cost of the chip due to the increased yield of the head chip.

1 is a schematic cross-sectional view of a conventional inkjet printhead.

FIG. 2 is a plan view illustrating a heater layer and a lead layer of the inkjet printhead illustrated in FIG. 1.

3 is a schematic cross-sectional view of an inkjet printhead according to an embodiment of the present invention.

4A to 4J are diagrams for describing a method of manufacturing an inkjet printhead according to an embodiment of the present invention.

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

111 ... substrate 112 ... insulating layer

113 Heater layer 114 Conductor layer

115 ... protective layer 116 ... cavitation prevention layer

120 ... chamber layer 122 .. ink chamber

130 ... Nozzle Plate 132 ... Nozzle

150 ... leveling layer

Claims (6)

A substrate having a heater layer formed thereon and a conductor layer for applying current to the heater layer; A planarization layer formed to protrude on the substrate to planarize an upper surface of the heater layer formed on the substrate and the conductive layer formed on both sides of the heater layer; A protective layer formed on upper surfaces of the heater layer and the conductive layer; A chamber layer defining an ink chamber stacked on top of the protective layer and filled with ink to be discharged; And And a nozzle plate stacked on the chamber layer and having nozzles through which ink is discharged. The method of claim 1, The thickness of the planarization layer and the thickness of the conductive layer is the same inkjet printhead. The method of claim 1, And the planarization layer is made of silicon oxide. Forming an insulating layer on an upper surface of the substrate; Forming a material layer on an upper surface of the insulating layer and patterning the material layer to form a planarization layer; Forming a heater layer on upper surfaces of the insulating layer and the planarization layer; Forming a conductive layer on both sides of the planarization layer so as to be flat with the heater layer positioned above the planarization layer; Forming a protective layer on upper surfaces of the heater layer and the conductive layer; Forming a chamber layer defining an ink chamber on top of the protective layer; And Forming a nozzle plate having a nozzle formed on an upper surface of the chamber layer. The method of claim 4, wherein And the conductive layer is formed to have the same thickness as the planarization layer. The method of claim 4, wherein Forming the conductive layer, Forming a predetermined metal layer on an upper surface of the heater layer; Providing an etching mask exposing the metal layer on the planarization layer; Wet etching the metal layer exposed through the etching mask to expose the heater layer on the planarization layer; And And soft-etching and removing the metal layer remaining protruding in the exposed edge portion of the heater layer.