KR20080008866A - Method of manufacturing an ink jet head - Google Patents

Abstract

A method for manufacturing an ink-jet head is provided to improve the yield of an ink-jet head by making the shapes and sizes of ink supply holes uniform. A method for manufacturing an ink-jet head comprises the steps of: forming pressure generating elements generating a pressure for discharging ink on a substrate, forming a chamber layer defining a side wall of an ink path on the substrate, forming a mask pattern on the substrate having the chamber layer, forming a front trench inside the substrate by etching the substrate using the mask pattern as an etching mask, removing the mask pattern, forming a nozzle layer provided with a plurality of nozzles corresponding to the pressure generating elements on the chamber layer and forming a lower ink supply hole connected to the front trench.

Description

{Method of manufacturing an ink jet head}

1 is a partial plan view of an inkjet head according to an embodiment of the present invention.

2 to 7 are cross-sectional views taken along line II ′ of FIG. 1 to explain a method of manufacturing an inkjet head according to an embodiment of the present invention.

Description of the main parts of the drawing

100 substrate 102 pressure generating element

106: chamber layer 110: front trench

112: sacrificial mold layer 114: nozzle layer

118: lower ink supply port 200: ink supply port

The present invention relates to a method of manufacturing an inkjet head, and more particularly, to a method of manufacturing an inkjet head having an ink supply port having a uniform and reproducible shape and dimensions.

An ink jet recording device is an apparatus for printing an image by discharging minute droplets of printing ink to a desired position on a recording medium. Such inkjet recording apparatuses are widely used because they are inexpensive and can print many kinds of colors at high resolution. The ink jet recording apparatus basically includes an ink jet head through which ink is substantially discharged, and an ink container in fluid communication with the ink jet head. The inkjet head is a thermal and electro-mechanical transducer using an electro-thermal transducer in accordance with a pressure generating element provided to generate pressure for ink ejection. It is classified into piezoelectric method using).

The inkjet head includes a silicon substrate provided in chip form and various components disposed on a top surface of the silicon substrate. An example of a thermal ink jet head is disclosed in US Pat. No. 4,882,595. The thermal inkjet head is disposed on the silicon substrate and has a sidewall of an ink flow path including a plurality of heat-generating resistors, an ink chamber and an ink channel to generate thermal energy for ink ejection. And a chamber layer defining a nozzle layer disposed on the chamber layer. The nozzle layer has a plurality of nozzles corresponding to each of the heating resistors. A bottom surface of the silicon substrate is attached to an ink container, and ink in the ink container is provided to the inkjet head through an ink feed hole penetrating the silicon substrate. Ink provided through the ink supply port is temporarily stored in the ink chamber via the ink channel. The ink stored in the ink chamber is instantaneously heated by the heat generating resistor and discharged onto the recording medium through the nozzle in the form of droplets by the pressure generated at this time. Thereafter, ink is refilled in the ink chamber through the ink channel.

The inkjet head should generally meet the following requirements. First, the manufacturing process should be simple, low manufacturing cost, and mass production possible. 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. That is, in order to obtain high resolution, it is necessary to be able to arrange a plurality of nozzles at high density. Third, for high speed printing, the cycle of refilling ink in the ink chamber after ejecting ink from the ink chamber should be as short as possible.

According to the conventional methods of manufacturing an inkjet head, an ink supply port penetrating the silicon substrate is formed by etching the silicon substrate from the back side thereof. As an etching process for the silicon substrate, a dry etching process such as a wet etching process using a strong alkaline solution such as TMAH (Tetramethyl Ammonium Hydroxide) as an etching solution or a sandblasting process has been applied. However, the process of forming the ink supply hole by etching the silicon substrate from the lower surface may have the following problems.

That is, since wet or dry etching proceeds from the back surface of the silicon substrate to the front direction, the outlet outline of the ink supply hole formed on the top surface of the silicon substrate is rough, and it is difficult to control the shape and dimensions reproducibly. In this case, the distance from the outlet outline of the ink supply port to the respective ink channels may be non-uniform so that the speed at which ink is refilled into the ink chamber after ink ejection may be non-uniform. As a result, the ink ejection frequencies in the respective ink chambers may be different from each other, thereby reducing the reliability of the inkjet head.

The technical problem to be achieved by the present invention is to improve the yield and reliability of the inkjet head by controlling the shape and dimensions of the ink supply port uniformly and reproducibly in the method of manufacturing the inkjet head.

In order to achieve the above technical problem, the present invention provides a method of manufacturing an inkjet head. The method includes forming pressure generating elements on the substrate to generate pressure for ink ejection. A chamber layer defining a sidewall of the ink flow path is formed on the substrate. A mask pattern is formed on a substrate having the chamber layer. The substrate is partially etched using the mask pattern as an etching mask to form a front trench in the substrate. The mask pattern is removed. A nozzle layer having a plurality of nozzles corresponding to the pressure generating elements is formed on the chamber layer. The substrate is etched from the rear surface to form a lower ink supply port in communication with the front trench.

In one embodiment, the mask pattern may be a photoresist pattern. Forming the photoresist pattern may include spin coating the photoresist at an angular speed of 500 rpm to 5000 rpm on the substrate having the chamber layer, and exposing and developing the photoresist. In this case, the photoresist may have a kinetic viscosity of 110 cSt or more at 25 ° C. and a specific gravity of 1.0 or more.

In another embodiment, the height of the chamber layer may be 10 μm to 30 μm.

In another embodiment, the front trench may have a depth of 10 μm to 100 μm.

In another embodiment, before forming the nozzle layer, a sacrificial mold layer filling the ink flow path and the front trench between the chamber layers may be formed. The sacrificial mold layer may be removed after forming the lower ink supply hole.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the scope of the invention to those skilled in the art will fully convey. In the drawings, the thicknesses of layers and regions are exaggerated for clarity.

FIG. 1 is a partial plan view of an inkjet head according to an embodiment of the present invention, and FIGS. 2 to 7 are lines I to I 'of FIG. 1 to explain a method of manufacturing an inkjet head according to an embodiment of the present invention. Are cross-sectional views taken along.

1 and 2, a substrate 100 is prepared. The substrate 100 is used in the manufacturing process of the semiconductor device, it may be a silicon substrate having a thickness of about 500㎛. Pressure generating elements 102 are formed on the substrate 100 to generate pressure for ink ejection. In the embodiments of the present invention, the pressure generating elements 102 may be exothermic resistors made of a high resistance metal such as tantalum or tungsten, an alloy including the high resistance metal such as tantalum aluminum, or polysilicon doped with impurity ions. have. The pressure generating elements 102 may be arranged in two rows on the substrate 100 as shown in FIG. 1, but are not limited thereto. In addition, the pressure generating elements 102 may be disposed in a straight line as shown in FIG. 1, or alternatively, may be arranged in a zigzag in an angular row. An insulating passivation layer 104 may be formed on the front surface of the substrate having the pressure generating elements 102. The insulating protective layer 104 is formed to prevent the pressure generating elements 102 from being corroded by ink, and may be formed of, for example, a silicon oxide film.

In addition, a wiring for supplying an electrical signal to the pressure generating elements 102, a conductive pad for electrically connecting the external circuit and the pressure generating elements 102, and the substrate 100 on the substrate 100. A silicon oxide thermal barrier layer may be further formed on the lowermost layer of the phase.

1 and 3, a chamber layer 106 defining a sidewall of an ink flow path is formed on the substrate 100. The ink flow path is provided with a passage of ink between ink chambers C including the pressure generating elements 102 therein and between the ink chamber C and an ink supply port to be described by a subsequent process. Channels H may be included. The chamber layer 106 may be formed by exposing and developing the photosensitive resin layer after forming the photosensitive resin layer on the substrate 100. The photosensitive resin layer may be formed by spin coating using a liquid photosensitive resin, or may be formed by heating and compressing the photosensitive dry film layer by a lamination method. The chamber layer 106 may be formed to have a height of about 10 μm to about 30 μm.

1 and 4, a mask pattern 108 is formed on the substrate 100 having the chamber layer 106. The mask pattern 108 may cover the chamber layer 106 and the pressure generating elements 102 and expose the substrate 100 between the pressure generating elements 102. As described above, when the pressure generating elements 102 are arranged in two rows on the substrate 100, the mask pattern 108 is arranged between the pressure generating elements 102 arranged in two rows. The substrate 100 may be exposed. In example embodiments, the mask pattern 108 may be a photoresist pattern. The photoresist pattern may be formed by coating a photoresist by performing a spin coating process on a substrate having the chamber layer 106, and exposing and developing the photoresist. The photoresist is coated on the substrate 100 after forming the chamber layer 106. Therefore, the step formed by the chamber layer 106 may act as a factor to inhibit the coating of the photoresist on the substrate 100 with a uniform thickness. Accordingly, the photoresist has a kinetic viscosity of about 110 cSt or more at about 25 ° C., so that even if the chamber layer 106 is previously formed on the substrate 100, the photoresist has 1.0 It may have a specific gravity above. In addition, the spin coating process for applying the photoresist may be performed at an angular speed of about 500 rpm to about 5000 rpm.

After the mask pattern 108 is formed, the substrate 100 is partially etched using the mask pattern as an etching mask to form a front trench 110 in the substrate 100. Etching the substrate 100 may be performed through a dry etching process, for example, a reactive ion etching (RIE) process or a deep reactive ion etching (DRIE) process. The DRIE process is also known as an ICP (Inductive Coupled Plasma) process. In particular, the DRIE process is suitable for etching silicon substrates having a thickness of about 500 μm by using a high concentration plasma source and alternately performing etching and protective layer deposition to obtain high aspect ratios. In this case, SF ₆ gas may be used as an etching plasma source, and C ₄ F ₈ gas may be used as a passivating plasma source. The front trench 110 may be formed to have a depth of about 10 μm to about 100 μm.

1 and 5, the mask pattern 108 is first removed. When the mask pattern 108 is a photoresist pattern, the photoresist pattern may be removed by an ashing process using an oxygen plasma. Next, a sacrificial mold layer 112 may be formed to fill the ink flow path between the chamber layer 106 and the front trench 110. More specifically, a positive photosensitive resin layer or a thermoplastic resin layer of polyimide or polyamide-based or thermoplastic resin layer is formed on the substrate 100 having the chamber layer 106 by spin coating. do. Thereafter, the positive photosensitive resin layer or the thermoplastic resin layer is planarized to expose the upper surface of the chamber layer 106 to form the sacrificial mold layer 102. The planarization may be performed by a chemical mechanical polishing (CMP) process.

After forming the sacrificial mold layer 112, a plurality of nozzles 114 ′ corresponding to the pressure generating elements 102 are provided on the chamber layer 106 and the sacrificial mold layer 112. The nozzle layer 114 is formed. The nozzle layer 114 may be formed through the following process. First, a nozzle material layer is formed on the chamber layer 106 and the sacrificial mold layer 112. The nozzle material layer may be formed of a photocurable resin layer or a thermosetting resin layer using a spin coating method. The nozzle material layer is then patterned to form the nozzle layer 114 with the nozzles 114 '. When the nozzle material layer is a negative photosensitive resin layer, the negative photosensitive resin layer may be patterned through an exposure and development process. In addition, when the nozzle material layer is a thermosetting resin layer, the thermosetting resin layer may be patterned by a photolithography process and an anisotropic etching process using an oxygen plasma.

1 and 6, after the nozzle layer 114 is formed, a rear mask pattern 116 is formed on the rear surface of the substrate 100 to expose a predetermined region of the substrate 100. In the present invention, the back surface of the substrate 100 may be used as a term referring to a surface opposite to the surface of the substrate 100 on which the pressure generating elements 102 are formed. The back mask pattern 116 May expose a rear surface of the substrate 100 in an area overlapping the front trench 110. The back mask pattern 116 may be formed of an insulating film, such as a silicon nitride film, or a rubber-based resin or photoresist. Subsequently, the lower surface ink supply hole 118 is formed by etching the substrate 100 from the rear surface using the rear mask pattern 116 as an etch mask. In this case, the substrate 100 may be etched by a wet or dry etching process. In addition, the substrate 100 may be performed to expose the sacrificial mold layer 112. The back mask pattern 116 is removed after the lower ink supply hole 118 is formed. The lower ink supply hole 118 may be formed to have the same area as the front trench 110 when viewed from a plan view as shown in FIG. 1, or may be formed to include the front trench 110 therein. Can be.

1 and 7, after the lower ink supply hole 118 is formed, the sacrificial mold layer 112 is dissolved and removed. The sacrificial mold layer 112 may be removed through the lower ink supply hole 118. The sacrificial mold layer 112 may be removed using, for example, a solvent such as glycol ether, methyl lactate or ethyl lactate. As a result of removing the sacrificial mold layer 112, an ink flow path including ink chambers C and ink channels H is finally formed in a region where the sacrificial mold layer 112 is removed. In addition, an ink supply port 200 including the front trench 110 and the lower ink supply port 118 is formed. The ink supply port 200 is formed to penetrate the substrate 100.

As described above, according to the exemplary embodiments of the present invention, the front trench 110 is formed by dry etching the substrate 100 from the surface on which the pressure generating elements 102 are formed, and the substrate 100. The ink supply port 200 is formed by etching the rear surface of the back side) to form the lower ink supply port 118 in communication with the front trench 110. As a result, the shape and dimensions of the outlet outline of the ink supply port 200 defined at the surface of the substrate 100 on which the pressure generating elements 102 are formed can be precisely and reproducibly adjusted. Therefore, the distance from the outlet outline of the ink supply port 200 to the respective ink chambers C can be adjusted uniformly and reproducibly, so that ink is refilled into the ink chambers C after ejecting the ink. The speed becomes uniform.

As described above, according to the present invention, the ink supply port of the inkjet head has a front trench formed by etching from the upper surface of the substrate on which the pressure generating elements are formed. As a result, the shape and dimensions of the ink supply port can be adjusted uniformly and reproducibly to improve the yield and reliability of the inkjet head.

Claims (7)

Forming pressure generating elements on the substrate to generate pressure for ink ejection, Forming a chamber layer on the substrate, the chamber layer defining a sidewall of the ink flow path, Forming a mask pattern on the substrate having the chamber layer, Partially etching the substrate using the mask pattern as an etching mask to form a front trench in the substrate, Remove the mask pattern, Forming a nozzle layer having a plurality of nozzles corresponding to the pressure generating elements on the chamber layer, And etching the substrate from a rear surface to form a lower ink supply port communicating with the front trench. The method of claim 1, And the mask pattern is a photoresist pattern. The method of claim 2, Forming the photoresist pattern, Spin coating the photoresist at an angular velocity of 500 rpm to 5000 rpm on the substrate having the chamber layer, Exposing and developing the photoresist. The method of claim 3, wherein The photoresist has a kinetic viscosity of 110 cSt or more at 25 ° C. and a specific gravity of 1.0 or more. The method of claim 1, The height of the chamber layer is a manufacturing method of the inkjet head, characterized in that 10㎛ to 30㎛. The method of claim 1, The front trench has a depth of 10㎛ to 100㎛ inkjet head manufacturing method characterized in that. The method of claim 1, Before forming the nozzle layer, the method further includes forming a sacrificial mold layer filling the ink channel and the front trench between the chamber layers, wherein the sacrificial mold layer is removed after forming the lower ink supply port. A method of manufacturing an inkjet head.

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