KR20060020444A - Fabrication method for the ink-jet print head - Google Patents

Abstract

The present invention relates to a method of manufacturing an inkjet print head, comprising: etching an upper surface of a substrate to form an ink chamber; Forming an oxide film on the surface of the substrate; Forming a heater and a lead layer on the oxide film and patterning the same; Forming a restrictor on the bottom of the ink chamber; Forming a sacrificial layer in the restrictor and the ink chamber; Forming a nozzle layer having a nozzle on the sacrificial layer; Forming a feed hole in a rear surface of the substrate; It provides a method of manufacturing an inkjet print head, characterized in that it comprises the step of removing the sacrificial layer.

According to the present invention, since the heater and the lead layer are directly formed on the upper portion of the substrate without forming the sacrificial layer, not only a sufficient process temperature can be ensured, but also the heater and the lead layer have no uniform angles, and thus a uniform thickness is not provided. It is possible to obtain a thin film having a, not only to improve the productivity, but also to maintain the characteristics of the heater well.

Inkjet printer, head, heater, cavitation.

Description

Fabrication method for the ink-jet print head

1 is a cross-sectional view showing a conventional general inkjet print head.

2 is a cross-sectional view showing another conventional inkjet print head.

3 is a cross-sectional view showing an embodiment of the inkjet print head according to the present invention.

4 is a perspective view of the chamber layer removed in the embodiment shown in FIG.

5A to 5J are sectional views showing respective processes of one embodiment of the method for manufacturing an inkjet print head according to the present invention.

<Explanation of symbols for main parts of the drawings>

100... Substrate, 112... Ink feed hole,

114. ... Ink chamber,

120... Silicon oxide film, 130. Heater layer,

140... Lead layer, 150... Nozzle Layer,

152. Nozzle, 160... Thermal Oxidation Film,

170... Sacrificial layer.

The present invention relates to a method of manufacturing an inkjet printhead, and more particularly, to an inkjet printhead used as a jetting means for jetting ink in an inkjet printer and a method of manufacturing the same.

An inkjet printer is a kind of image forming apparatus which injects ink stored in a cartridge into the surface of a print medium in the form of fine droplets to obtain a print of a desired form, and ink stored in the cartridge is ejected through the head. At this time, the method of spraying ink can be largely divided into a thermal drive method and a piezoelectric drive method. The former is equipped with a heater in the head to form a bubble due to the heat generated from the heater and then spray the ink droplets by the pressure The latter is a method of spraying ink droplets at a pressure generated due to mechanical deformation of the piezoelectric element by applying power to the piezoelectric element.

1, there is shown a conventional general thermally driven inkjet print head. The head is provided with an ink feed hole 12 receiving ink from an ink cartridge on the upper surface of the substrate 10, and a restrictor 16 for supplying ink supplied through the feed hole 12 to the inside of the head. It has a chamber layer 14 having an ink chamber 18 to temporarily store it. A nozzle 20 is formed above the chamber layer 14, and a heater 22 is formed below the nozzle 20. On the other hand, in order to prevent the heater 22 from being damaged by the reaction with the ink, a protective layer 24 is formed on the surface. In addition, the heater 22 is connected to the pad 26, and the pad 26 is connected to the inkjet printer body through a flexible circuit board (not shown). Here, the structure of the head is shown schematically and actually has a more complicated structure.

On the other hand, when a pulse-type current is applied to the heater 22, it is instantaneously heated to form bubbles on the surface of the heater 22, whereby the ink droplet 28 causes the nozzle 20 to increase the pressure. Will be discharged through. However, in the illustrated form, heat transfer occurs only through the top surface of the heater 22, and the heat generated at the bottom of the heater 22 raises the temperature of the head 14 and is not used to heat the ink. Moreover, the heat transfer efficiency is further lowered due to the protective layer 24 located on the upper surface of the heater 22.

In order to solve this problem, as shown in FIG. 2, US Pat. No. 6,669,333 forms a chamber layer 54 on the substrate 50 having the ink feed hole 52 and the restrictor 56. Since the heater 58 for heating the ink flowing through the restrictor 56 is positioned at the center of the ink chamber 57, a technique in which a heating can be performed at both sides of the heater 58 has been disclosed. In the above technique, since it is not necessary to form the protective layer as described above by using an ink having a lower conductivity than in the related art, not only can the heat transfer efficiency be increased, but also the heating is performed through both sides of the heater. It is possible to discharge ink droplets even with electric power.

In addition, if the power is cut off after the ejection of the droplets, the bubble is reduced and the cavitation force (cavitation force) acts on the surface of the heater, this may cause damage to the heater deformed, it is shown in Figure 2 In the form, since bubbles are generated and dissipated on both sides of the heater in opposite directions, the cavitation force is canceled with each other, thereby greatly reducing the effect on the heater, thereby extending the life of the heater.

However, in practice, the size of the bubbles generated on both sides of the heater does not exactly match, so the cavitation force acts on the heater at the time of bubble extinction. In addition, the above technique is likely to be nonuniform in terms of the heater thickness of the bent portion because the heater is not present on the same plane and is present at a right angle.

The heater is generally formed by depositing a heater material in the form of a thin film by sputtering, CVD, or the like, and then patterning the heater. Thus, it is very difficult to form the heater to have a desired dimension in a portion that is bent at right angles as shown. That is, the thickness of the thin film becomes nonuniform in the vicinity of the bent portion, but when the thickness of the bent portion is thin, there is a high possibility that an electrical short occurs because current density is concentrated. Therefore, not only is it disadvantageous in terms of productivity, but it is difficult to accurately control the amount of heat generated by the heater during operation.

In addition, the nozzle layer 59 is formed after forming a sacrificial layer using a photoresist in the chamber layer 54, and the sacrificial layer is removed during the manufacturing process. At this time, since the etching may proceed to the same portion as the chamber layer 54 in the process of removing the sacrificial layer, the material of the chamber layer 54 is inevitably limited. For example, it is impossible to use a polymer-based material as the chamber layer 54 and the nozzle layer 59.

In addition, the thin film constituting the heater and the lead should be formed on the sacrificial layer made of the photoresist, but due to the characteristics of the material constituting the sacrificial layer, the process temperature required for forming the thin film is also restricted. Because of this, it is difficult to form high quality thin films and there are limitations in the heater materials that can be used. In addition, since complete removal is difficult upon removal of the sacrificial layer, some sacrificial layer is likely to remain, which may cause clogging of the flow path or nozzle during operation.

The present invention has been made to overcome the disadvantages of the prior art as described above, the technical problem to provide a method of manufacturing an inkjet print head that can extend the life of the heater by minimizing the influence of the cavitation force.

In addition, the present invention minimizes the number of formation of the sacrificial layer during the manufacturing process, thereby sufficiently securing the process temperature at the time of forming a thin film such as a heater or a lead, and preventing ink clogging due to the remaining sacrificial layer. It is another technical problem to provide a manufacturing method of a print head.

In order to achieve the above technical problem, the present invention comprises the steps of forming an ink chamber by etching the upper surface of the substrate; Forming an oxide film on the surface of the substrate; Forming a heater and a lead layer on the oxide film and patterning the same; Forming a restrictor on the bottom of the ink chamber; Forming a sacrificial layer in the restrictor and the ink chamber; Forming a nozzle layer having a nozzle on the sacrificial layer; Forming a feed hole in a rear surface of the substrate; It provides a method of manufacturing an inkjet print head, characterized in that it comprises the step of removing the sacrificial layer.

That is, since the sacrificial layer is formed at the time of forming the ink chamber as in the prior art, instead of forming the chamber layer thereon, the substrate is etched to form the chamber, thereby eliminating the need to form the sacrificial layer at the time of chamber formation. As a result, the process of forming and removing the sacrificial layer can be omitted, which simplifies the process and prevents nozzle clogging due to the sacrificial layer residue.

Preferably, the ink chamber may be formed such that the sidewall is inclined by forming a thermal oxide film on the surface of the substrate and then using it as an etching mask. As a result, the ink chamber may be formed to have an angle of about 54.7 ° with respect to the substrate, and when the heater and lead layers are formed on the upper portion of the ink chamber by the evaporation method, the ink chamber may not be bent at right angles, thereby obtaining a uniform film thickness. Will be.

On the other hand, the sacrificial layer may be formed by applying a photoresist to the upper surface of the substrate, and then polished until the surface of the substrate is exposed by the CMP method.

The present invention also includes etching an upper surface of a substrate to form an ink chamber; Forming an oxide film on the surface of the substrate; Forming a heater and a lead layer on the oxide film and patterning the same; Forming a restrictor on the bottom of the ink chamber; Laminating a dry film on the sacrificial layer to form a nozzle layer, and forming a nozzle at a center thereof; It provides a method of manufacturing an inkjet print head comprising the step of forming a feed hole on the back of the substrate.

In this case, since the nozzle layer can be formed by laminating a solid dry film, there is an advantage that a sacrificial layer for the nozzle layer is also unnecessary. Here, the nozzle may be formed by exposing the dry film using a mask.

Preferably, the ink chamber may be formed such that the sidewall is inclined by forming a thermal oxide film on the surface of the substrate and then using it as an etching mask.

Hereinafter, with reference to the accompanying drawings, it will be described in detail an embodiment of the manufacturing method of the inkjet print head according to the present invention.

3, there is shown a cross section of an inkjet print head manufactured by an embodiment of the manufacturing method according to the present invention. The inkjet print head has a substrate 100 made of a silicon wafer, and an ink feed hole 112 through which ink supplied from an ink cartridge (not shown) is primarily formed on a bottom surface of the substrate 100. The ink feed hole 112 is formed in common throughout the inkjet print head, and a restrictor 114 communicating with each ink chamber 116 is formed on the ink feed hole 112.

The ink chamber 116 has a trapezoidal shape that becomes narrower toward the bottom, and two sidewalls are inclined. Here, the inclination angle of the side wall with respect to the surface of the substrate is about 54.7 degrees. The ink chamber 116 is a space that is temporarily stored before the ink flowing through the restrictor 114 is discharged to the outside through the nozzle. Meanwhile, a silicon oxide film 120 is formed on the top surface of the ink chamber 116 and the top surface of the substrate. The silicon oxide film 120 is formed by oxidizing a surface of the substrate, and is formed to insulate the substrate from a heater and a lead.

A heater layer 130 is formed on the silicon oxide film 120, and a lead layer 140 is formed on the heater layer 130 (see FIG. 4). The heater layer 130 is formed over the upper portion of the substrate 100 and the ink chamber 116, most of the heater layer 130 is covered by the lead layer 140, the ink chamber 116 The portion 132 located on the side wall of the NX is exposed to the outside and contacts the ink.

The lead layer 140 is positioned above the heater layer 130 and is also present at an end of the ink chamber 116 side of the heater layer 130. That is, since the heater layer 130 has two narrow bands arranged side by side, a portion of the lead layer 140 may be connected to each other by connecting the two bands constituting the heater layer 130 to each other. 142 is connecting the heater layer 130 to each other. That is, the + and-electrodes are connected to the two bands, respectively, so that a current flows along the two bands and the heater layer and the portion 142, and the heater is heated in this process.

Thus, the inkjet print head shown in FIG. 3 has two heaters that operate independently of each other inside the ink chamber 116. That is, in FIG. 3, only one of the left and right heaters may be operated, and two heaters may be operated at the same time, thereby allowing the size of the droplet of ink to be discharged to be adjusted.

The nozzle layer 150 is formed on the lead layer 140. Nozzle 152 is formed at the center of the nozzle layer 150, if bubbles are generated in the ink chamber 116 due to the heating of the heater, the ink droplets through the nozzle 152 due to the increased pressure thereby It is discharged to the outside. At this time, after the ink droplets are discharged, the cavitation force acts as the bubble is reduced, but the cavitation force acts toward the point located between the two heaters, so that the heater is hardly affected.

The inkjet print head may be manufactured by the following process.

First, a thermal oxide film 160 is formed on the upper surface of the substrate 100 made of a silicon wafer to a thickness of 0.2 μm (FIG. 5A). Thereafter, after the thermal oxide film 160 is patterned to form an etching mask, etching is performed to form an ink chamber 116 having an inclination angle of about 54.7 ° as illustrated in FIG. 5B.

After the formation of the ink chamber 116 is completed, the oxide film 120 is formed again on the upper surface of the substrate 110 and the surface of the ink chamber 116 to a thickness of 2 μm, and then a heater made of a heater material thereon. The lead layer 140 made of the layer 130 and the metal thin film is formed by vapor deposition (FIG. 5C), and then patterned as shown in FIG. 4 (FIG. 5D).

Thereafter, the heater layer and the oxide film existing on the bottom surface of the ink chamber 116 are removed, and the restrictor 114 is formed by dry etching (FIG. 5E). When the formation of the restrictor 114 is completed, a sacrificial layer photoresist is applied to the surface by spin coating to form a sacrificial layer 170 (FIG. 5F), and the sacrificial layer 170 is formed by using the CMP method. The sacrificial layer 170 is present only in the ink chamber 116 (FIG. 5G).

When polishing of the sacrificial layer 170 is completed, a negative photoresist is applied on the sacrificial layer 170 and the substrate 100 to form the nozzle layer 150 (FIG. 5H). Thereafter, the substrate is exposed using a mask to form the nozzle 152 (FIG. 5I), and the back surface of the substrate 100 is etched by a dry etching method to form an ink feed hole 112 (FIG. 5J). Finally, the sacrificial layer 170 filled in the ink chamber 116 is removed to complete the manufacturing.

In this case, the nozzle layer 150 may be formed using a dry film. That is, after completion of the state shown in FIG. 5E, without forming the sacrificial layer 170, laminating a dry film on the upper portion thereof, attaching the upper portion of the substrate 100, and exposing the nozzle 152 to expose the nozzle 152. Since the fabrication of the layer 150 is completed, the inkjet print head can be manufactured without forming the sacrificial layer. In this case, the feed hole 112 may be formed after forming the restrictor 114 in FIG. 5E.

According to the present invention having the above-described configuration, since the heater and the lead layer are directly formed on the upper portion of the substrate without forming the sacrificial layer, sufficient process temperature can be secured, and a portion that is bent at right angles to the heater and the lead layer is Since it does not exist, it is possible to obtain a thin film having a uniform thickness, thereby not only improving productivity but also maintaining the characteristics of the heater well.

In addition, the cavitation force does not directly affect the surface of the heater, but acts between two heaters located on the inclined sidewall, thereby preventing damage to the heater by the cavitation force.

Claims (5)

Etching the upper surface of the substrate to form an ink chamber; Forming an oxide film on the surface of the substrate; Forming a heater and a lead layer on the oxide film and patterning the same; Forming a restrictor on the bottom of the ink chamber; Forming a sacrificial layer in the restrictor and the ink chamber; Forming a nozzle layer having a nozzle on the sacrificial layer; Forming a feed hole in a rear surface of the substrate; Removing the sacrificial layer. The method of claim 1, The ink chamber is a method of manufacturing an inkjet print head, characterized in that the sidewall is formed to be inclined by using a thermal oxide film formed on the surface of the substrate as an etching mask. The method of claim 1, The sacrificial layer is formed by applying a photoresist to the upper surface of the substrate, and then polished until the surface of the substrate is exposed by the CMP method. Etching the upper surface of the substrate to form an ink chamber; Forming an oxide film on the surface of the substrate; Forming a heater and a lead layer on the oxide film and patterning the same; Forming a restrictor on the bottom of the ink chamber; Laminating a dry film on the sacrificial layer to form a nozzle layer, and forming a nozzle at a center thereof; Forming a feed hole in a rear surface of the substrate. The method of claim 4, wherein The ink chamber is a method of manufacturing an inkjet print head, characterized in that the sidewall is formed to be inclined by using a thermal oxide film formed on the surface of the substrate as an etching mask.

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