KR100438711B1 - manufacturing method of Ink jet print head - Google Patents

Abstract

A method of manufacturing an inkjet print head is disclosed. The disclosed manufacturing method includes: a first step of forming a nozzle plate including a heater on an upper surface of a substrate; Forming a nozzle on the nozzle plate; A third step of forming an ink chamber on the substrate, the ink chamber being located below the heater provided in the nozzle plate and having an inner surface of the nozzle plate thereon; A fourth step of penetrating through the restrictor through which ink passes through the bottom of the ink chamber; And a fifth step of forming a thermally conductive layer on the inner wall of the restrictor, on the inner wall of the ink chamber, and on the inner surface of the nozzle plate located above the ink chamber by atomic layer deposition. This method can effectively suppress thermal accumulation on the nozzle plate and the ink, and effectively suppress the adsorption of dyes present in the ink, and can protect the components around the chamber due to the bubble shrinkage.

Description

Manufacturing method of Ink jet print head

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ink jet print head, and more particularly, in a structure in which a heater is formed in a nozzle plate, heat accumulation in the nozzle plate and ink, and adsorption of dyes present in the ink. It relates to a method of manufacturing an ink jet printer head that can effectively suppress the back.

Ink jet printers use a heat source to generate bubbles (bubbles) in the ink and discharge the ink by this force, using an electro-thermal transducer (bubble jet method), and a piezoelectric material. There is an electro-mechanical transducer in which ink is ejected by a volume change of ink caused by deformation of the piezoelectric body.

Electro-thermal transducers (bubble jet) have top-shooting and side-shooting depending on the direction of bubble growth and the direction of ejection of ink droplets. ) Is classified into a back-shooting method. Here, the top-shooting method is a bubble growth direction and the ink droplet ejection direction is the same, the side shooting method is a bubble growth direction and the ink droplet ejection direction is a right angle and the back-shooting method is a bubble growth The ink ejection method in which the direction and the ejection direction of the ink droplets are opposite to each other.

U. S. Patent 5,760, 804 discloses a basic principle of a back-shooting method and an ink jet head applying the same. U.S. Patents 4,847,630 and 6,019,457 also suggest various forms of back-shooting schemes of more advanced structure.

1 is a schematic cross-sectional view of one of the conventional ink jet print heads disclosed in US Pat. No. 6,019,457.

A hemispherical chamber 1a of the substrate 1 made of silicon or the like is formed, and an ink inlet 1b connected to an ink source (not shown) is formed in the lower center thereof. Above the chamber 1a, a nozzle plate 2 having a nozzle 3 through which the ink droplet 5a is discharged is located.

The nozzle plate 2 includes a thermal insulation layer 2a and a CVD chemical vapor deposition over coat 2b thereon. The insulating layer 2a and the overcoating layer 2b of these nozzle plates 2 correspond to one part of the actual substrate 1.

In the nozzle plate 2, a heater 8 is formed adjacent to and surrounding the nozzle 3. This heater 8 is located at the interface between the insulating layer 2a and the overcoating layer 2b, and the upper part of the heater 8 transfers most of the heat from the heater 8 to the ink 5 in the chamber 1a. A thermal shunt 9 is located that transfers heat to the substrate 1 through the insulating layer 2a.

In such a conventional ink jet print head, when a current pulse is applied to the heater 8, heat is generated in the heater 8 and bubbles 7 are generated from the inner surface of the insulating layer 2a in contact with the heater 8. ) Is generated. Thereafter, while the heat generation from the heater 8 is continued, it is continuously supplied with heat to expand. The expansion of the bubble 7 causes a pressure to be applied to the ink 5 filled in the chamber 1a so that the ink 5 near the nozzle 3 is discharged in the form of an ink droplet 5a to the outside through the nozzle 3. Discharged. Then, the ink is refilled in the ink chamber while the ink is sucked through the ink channel.

In such a back-shooting ink jet print head, the heaters 8 arranged around the nozzles 3 of the nozzle plate 2 are formed with the insulating layer 2a constituting the nozzle plate 2 as described above. Located between the overcoating layers 2b, this heater 8 is connected to an electric line (not shown) for applying a current. This electric wire is also located between the insulating layer 2a and the overcoating layer 2b.

When a current is applied to the heater 8, the heat generated from the heater 8 is transferred to the ink in the chamber to contribute most to the bubble generation, but the remaining excess heat can be accumulated in the nozzle plate 2 as it is, It is suppressed by the thermal shunt 9. That is, the thermal shunt 9 transfers the excess heat that is not transferred to the ink 5 in the chamber 1a to the substrate 1, thereby thermally accumulating the nozzle plate 2, that is, the temperature of the nozzle plate 2. The rise is suppressed. When the temperature of the nozzle plate 2 rises to a temperature higher than the reference, problems such as shortening of the life of the head and deterioration of the discharge performance are caused. This problem of thermal accumulation does not occur in the structure in which the heater is formed on the substrate, but is formed in the membrane plate nozzle plate having a large heat transfer resistance, such as in a portion separated from the substrate, for example, an ink jet print head as described above. Occurs when

In this way, the thermal shunt is applied to improve the problem of heat accumulation in the ink jet head in which the heater is formed in the nozzle plate. However, the thermoelectric shunt structure has a disadvantage in that sufficient heat transfer or discharge is difficult. In addition, since the thermal shunt is formed of a conductor such as aluminum and extends upwardly to and close to the heating element, thermal stress due to a difference in thermal expansion coefficient between the thermal shunt and the upper and lower material layers during use. The generation of cracks may be a concern.

In addition, a conventional ink print head is provided with an insulating layer containing silicon oxide (SiO _x ) or Si. Since these materials are mostly hydrophilic, the constituents, particularly dyes, etc. present in the ink are physically and / or chemically absorbed. Kogation can easily occur. This adsorption occurs, for example, on the inner side of the insulating layer 2a supporting the heater 8 in FIG. 1, which in turn prevents heat from the heater 8 from being transferred to the ink 5. .

On the other hand, due to the strong negative pressure generated after the occurrence of bubble generation (or shrinkage), a physical impact is applied to the structure near the orifice (nozzle), for example, the insulating layer 2a under the heater, and thus the insulating layer Cracking may occur in (2a), which results in the head being no longer usable.

A first object of the present invention is to provide a method of manufacturing an ink jet print head which can more effectively suppress the heat accumulation in the nozzle plate and ink, to improve the conventional problems as described above.

A second object of the present invention is to provide a method of manufacturing an ink jet print head which can effectively prevent ink adsorption on the chamber middle, in particular, the nozzle plate inner surface.

It is a third object of the present invention to provide a method of manufacturing an ink jet print head, which can effectively protect a structure around a nozzle from an impact around the nozzle generated during bubble shrinkage and extinction.

1 shows an example of a conventional ink jet print head.

2A is a schematic plan view of a first embodiment of an ink jet print head of the present invention.

FIG. 2B is a cross sectional view taken along the line A-A of FIG. 2A showing a chamber and its adjacent elements.

3 is a schematic cross-sectional view of a second embodiment of the ink jet print head of the present invention.

4A to 5B are process drawings showing one embodiment of a method of manufacturing an ink jet print head according to the present invention.

According to the present invention to achieve the above object,

Forming a nozzle plate including a heater on an upper surface of the substrate;

Forming a nozzle on the nozzle plate;

A third step of forming an ink chamber on the substrate, the ink chamber being positioned below the heater provided on the nozzle plate and on which an inner surface of the nozzle plate is located;

A fourth step of penetrating through the restrictor through which ink passes through the bottom of the ink chamber;

And a fifth step of forming a thermally conductive layer on the inner wall of the restrictor, the inner wall of the ink chamber and the inner surface of the nozzle plate located above the ink chamber by atomic layer deposition. Is provided.

According to a preferred embodiment of the manufacturing method of the present invention, the step of forming an ink supply manifold corresponding to the ink chamber on the back of the substrate between the third step and the fourth step is further performed, In the fourth step, the restrictor is formed to connect the chamber and the manifold, and through the fifth step, the thermal conductive layer is formed on the inner surface of the manifold.

In addition, according to another preferred embodiment of the manufacturing method of the present invention, a bubble guide forming step of extending a predetermined length from the nozzle to the chamber between the second step and the third step is further performed, and thus The thermal conductive layer is formed on the surface of the bubble guide through step 5.

According to the manufacturing method of the present invention, the thermal conductive layer is preferably formed of any one selected from the group consisting of Ta, W, Cu, Al, Cr, Pt, TiN, TaN, Si ₃ N ₄ , more preferably The thermal conductive layer is formed of TiN.

Hereinafter, exemplary embodiments of the ink jet print head according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2A is a schematic plan view of a first embodiment of an ink jet print head according to the present invention, and FIG. 2B is a cross-sectional view taken along the line A-A of FIG. 2A.

As shown in FIG. 2A, in the print head 100 according to the present invention, the nozzles 180 corresponding to the ink chambers 140 of the plurality of substrates 100 are arranged in a plurality of rows (two rows in this embodiment). It is arrange | positioned at the nozzle plate 120. The nozzle plate 120 is a membrane formed on the substrate 110 described later. A plurality of pads 100a are arranged in a line at predetermined intervals along opposite long sides of the print head 100. The pad 100a is a terminal for applying an electrical signal to the heaters 130 to be described later. A transistor for controlling an electrical line between the pad 100a and the heater 130 and in some cases, the electric signal for the heater. There may be a switching element such as. Herein, the switching element is positioned between the substrate 110 and the nozzle plate 120 and is formed by a general semiconductor manufacturing process for the substrate 110. The application of such a switching element, and its position or structure, etc. can be easily applied by a general technique, and because it is not related to the present invention will not be described further deeply.

2B, a hemispherical chamber 140 is formed at the center of the upper surface of the substrate 110. A rectangular channel manifold 170 is formed at the bottom of the hemispherical chamber 140, and ink from the manifold 170 is discharged through the restrictor 160 as a flow path formed at the bottom of the ink chamber 140. It may be supplied to the ink chamber 140. On the upper surface of the substrate 110, a nozzle plate 120 of a multi-layer structure is provided according to the structural feature of the bathing method. The nozzle plate 120 is a membrane formed by stacks sequentially formed from the surface of the substrate 100. The nozzle plate 120 is formed with a nozzle 180 positioned at the center of the chamber 140.

The nozzle plate 120 includes a first insulating layer 120a, a second insulating layer 120b, and a third insulating layer 120c. And a heater 130 formed to surround the nozzle 180 between the first insulating layer 120a and the second insulating layer 120b. The heater 130 is formed adjacent to the nozzle 180 between the first insulating layer 120a and the second insulating layer 120b. The wiring layer 15 connected to the heater 130 is formed between the second insulating layer 120b and the third insulating layer 120c. In the above structure, the upper insulating layer 120c is composed of two stacks including a passivation layer instead of a single layer, and the hydrophobic coating layer 190 is formed thereon.

In addition to the above structure, a heat conductive layer 191, which characterizes the present invention, is formed in all parts except the upper surface of the nozzle plate. That is, the thermal conductive layer 191 is formed on the inner surface of the nozzle 180 and the entire inner surface of the ink chamber 140, the inner surface of the restrictor 160, the inner surface of the manifold 170, and the bottom surface of the substrate 110. have. The thermal conductive layer 191 is formed on all parts to which the ink can be contacted, and is not formed on the upper surface of the nozzle plate 120 as described above.

The thermally conductive layer is preferably formed of any one selected from the group consisting of Ta, W, Cu, Al, Cr, Pt, TiN, TaN, Si ₃ N ₄ . According to a preferred embodiment of the present invention, the thermal conductive layer is formed of TiN.

The thermal conductive layer 191 may be formed on the upper surface of the nozzle plate 120 when electrically insulative, such as TiN, TaN, Si ₃ N ₄ , and electrically conductive such as Ta, W, Cu, Al, Cr, and Pt. In the case of having a thermal conductive layer 191 after the process of removing the portion existing on the upper surface of the nozzle plate 120 should be performed.

The portion of the thermal conductive layer 191 formed on the bottom surface of the substrate 110 and the portion formed inside the nozzle 180 are optional elements. That is, the comprehensive technical scope of the present invention is that the thermal conductive layer 191 is formed on the inner surface of the ink chamber 140 and on the inner surface of the restrictor 160. This thermal conductive layer 191 will be formed by atomic layer deposition according to the method according to the present invention. The atomic layer deposition method applies the principle of forming a thin film of atomic layer units by reacting in atomic layer units only in the adsorbed state of the substrate so that each material is time-divided so as to exclude the space reaction between the raw materials to be supplied. This atomic layer deposition method is described in more detail later.

3 is a schematic cross-sectional view of a second embodiment of an ink jet print head according to the present invention.

The ink jet print head shown in FIG. 3 has a structure in which the bubble guide 180a extending from the inner surface of the nozzle plate 120 to the ink chamber 140 side is added to the structure of the first embodiment. The bubble guide 180a is a means for guiding the bubble to grow below the ink chamber 140 when bubbles are generated from the inner surface of the nozzle plate 120 by the heat from the heater 130. In the second embodiment, the heat conductive layer 191, which characterizes the present invention, is formed on both the inner and outer surfaces of the bubble guide 180a. An essential requirement in the second embodiment is that the heat conductive layer 191 is formed on the inner and outer surfaces of the bubble guide 180a, the inner surface of the chamber 140, and the inner surface of the restrictor 160. In addition, the manifold The inner surface of the 170, the bottom of the substrate 110, and the like may be selectively formed.

In the first and second embodiments described above, the manifold 170 is described as being present in some cases, but in some cases, the manifold 170 is not formed on the substrate 110 itself. There may be. Thus, in the inkjet printhead of the present invention, the manifold is not an essential component. If the substrate 110 itself is not provided with a fold may be provided by a separate member, this part is beyond the technical scope of the present invention will not be described any more.

The physical properties of the thermally conductive layer in the inkjet printhead of the present invention as described above should be a material that is physically stronger than silicon or silicon oxide constituting the substrate against external impact with high thermal conductivity. It must also be physically hydrophilic and the ink, especially the components of the ink, not reactive with the dye. The requirements of these thermally conductive layers are relatively satisfied by the above-mentioned materials, and therefore the present invention uses these materials as preferred materials for thermally conductive layers, such as Ta, W, Cu, Al, Cr, Pt, TiN, TaN, Si ₃ N _4. And the like, in particular, TiN is preferred.

The high thermal conductivity of the thermal conductive layer 191 effectively prevents the ink discharge performance deterioration due to the heat accumulated in the ink by dissipating the heat of the ink contained in the ink chamber supplied from the heater to the outside through the bottom of the substrate.

In addition, the strong physical properties against external shocks protect the inner wall of the chamber and the structure around it, such as a nozzle plate, from shocks generated during sudden bubble dissipation or shrinkage.

In addition, hydrophilicity and non-reactivity with dyes suppress an increase in thermal resistance due to adsorption of dyes to the ink chamber inner wall and the inner surface of the nozzle plate.

Hereinafter, an embodiment of a method of manufacturing an ink jet print head according to the present invention will be described in detail. Here, the object of manufacture is the inkjet print head of Example 2 described above, and the film forming method and the patterning method applied to the manufacturing method of the present invention do not limit the technical scope of the present invention unless specifically stated as a known method. Do not.

The inkjet printhead manufacturing method according to the present invention may be classified into the following steps.

First step: forming a nozzle plate including a heater on the upper surface of the substrate

Second step: forming a nozzle on the nozzle plate

Third step: forming an ink chamber on the substrate, which is located below the heater provided in the nozzle plate and on which the inner surface of the nozzle plate is located.

Step 4: penetrating through the restrictor through which ink passes to the bottom of the ink chamber

Step 5: forming a thermal conductive layer on the inner wall of the restrictor, the inner surface of the ink chamber and the inner surface of the nozzle plate located above the ink chamber by atomic layer deposition.

By the way, in the embodiment of the manufacturing method of the inkjet printhead according to the present invention described below:

Forming an ink supply channel corresponding to the ink chamber on the rear surface of the substrate between the third and fourth steps;

In the fourth step, the restrictor is formed to connect the chamber and the channel;

And the thermally conductive layer is formed on the inner surface of the manifold through the fifth step.

And further comprising forming a bubble guide extending from the nozzle to the chamber by a predetermined length between the second and third steps. Such additional steps in this embodiment are optional items limited to this embodiment.

As shown in FIG. 4A, a silicon oxide first insulating film 120a is formed on a surface of a substrate 110 such as a Si wafer by PE-CVD, and then an annular or omega heater 130 is formed thereon. . The heater 130 may have various shapes surrounding the central axis (Y-X) of the nozzle formation region (A). The heater 130 is formed through polysilicon deposition, impurity doping and mask formation, and patterning by RIE.

As shown in FIG. 4B, a second insulating layer 120b such as silicon nitride is formed on the upper surface of the substrate 110 by CVD or the like.

As shown in FIG. 4C, a contact hole 121b for electrical connection to the heater 130 is formed through a photolithography process on the second insulating layer 120b.

As shown in FIG. 4D, a wiring layer 150 is formed on the second insulating layer 120b. The formation of the wiring layer 150 involves a patterning process through a photolithography process including deposition of aluminum or aluminum alloy by a sputtering apparatus, mask formation, and etching.

As shown in FIG. 4E, a third insulating layer 120c is formed on the stack. In this case, the third insulating layer 120c is preferably an inter-metal dielectric (IMD). Since the third insulating layer 120c protects the heater 130, it is necessary to have a predetermined thickness. Therefore, as shown in FIG. 4F, the silicon oxide fourth insulating layer 120d is formed on the third insulating layer 120c through PE-CVD. Herein, the fourth insulating layer 120d may be viewed as an extended portion of the third insulating layer 120c.

As shown in FIG. 4G, after forming the photoresist mask layer 201 having the window 202 corresponding to the well area A ′ for the nozzle, the photoresist mask layer 201 is formed on the fourth insulating layer 120d. By removing the portion of the insulating layer on the substrate 110.

As shown in FIG. 4H, a portion of the substrate 110 in the well region A 'is etched to a predetermined depth using an ICP RIE or the like. Through this process, the well 203 formed by the etching portion of the insulating layer and the substrate is formed. After the well 203 is formed, the mask layer 201 is removed.

As shown in FIG. 4I, TEOS (Tetraethoxysilane) is deposited on the stack on the substrate 110 by PE-CVD to form a thin film layer 181a for bubble guide formation. At this time, the thin film layer 181a is formed to a predetermined thickness on the uppermost layer of the stack and the inner wall and the bottom of the well 203.

As illustrated in FIG. 4J, the bubble guide 180a is completed by removing the TEOS thin film layer 181a except for the inner wall of the well 203 by dry etching such as RIE.

As shown in FIG. 4K, the thin film formed on the bottom surface of the substrate 110 by a film forming process is removed by polishing or the like, and then a mask layer 204 having a manifold forming window 205 is formed thereon.

As shown in FIG. 4L, the portion of the substrate exposed through the window 205 of the mask layer 204 is anisotropically etched to a predetermined depth to form the manifold 170.

As shown in FIG. 4M, an etching gas is supplied to the well 203 by a dry etching apparatus such as an XeF ₂ etching apparatus to form a hemispherical ink chamber 140 having a predetermined depth.

As shown in FIG. 4N, the restrictor 160 as a flow path is formed at the bottom of the ink chamber 140 by a dry etching method.

As shown in FIG. 5A, in a state in which the bottom surface of the substrate 110 faces upward, an atomic layer deposition (ALD) is performed by sequentially supplying source-divided source gas or radicals. 191). In this embodiment, the vertical growth method is applied, and thus radicals by the source gas or a plasma thereof are supplied from above the substrate 110. According to this ALD, the thermal conductive layer 191 is formed on the entire surface of the substrate 110, the nozzle plate 120, and the like.

As shown in FIG. 5B, the thermal conductive layer 191 formed on the upper surface of the nozzle plate 120 is removed by a dry etching method such as RIE, and the nozzle 180, the bubble guide 180a, the chamber 140, The thermal conductive layer 191 remains on the restrictor 160, the inner surface of the manifold 170, and the bottom surface of the substrate 110. However, as described above, when the thermal conductive layer 191 has electrical insulation, it may not be removed.

Hereinafter, the conditions of the ALD process described with reference to FIG. 5A will be briefly described.

Growth film fair Reaction gas TiN Thermal ALD or PE-ALD (TiCl ₄ , NH ₃ ) TaN PE-ALD (TaCl ₅ , NH ₃ ) or (Ta organic metal (MO) source, NH ₃ ) Si ₃ N ₄ PE-ALD (SiH ₄ , NH ₃ ) Ta PE-ALD (TaCl ₅ , H ₂ ) or (Ta organometallic source, H ₂ ) W PE-ALD (WF ₆ , H ₂ ) Cu, Al, Cr or Pt PE-ALD (Organic metal source, H ₂ )

As shown in Table 1, the heat conductive layer formed by the manufacturing method of the present invention is formed of any one of TiN, TaN, Si ₃ N ₄ , Ta, W, Cu, Al, Cr, Pt. . These materials are commonly characterized by high thermal conductivity and physically strong resistance, and hydrophilicity and non-reactivity with dyes. This non-reactivity prevents the adsorption of the dye in the ink in all the elements with which the ink comes into contact, such as the ink chamber.

The TiN thermal conductive layer may be formed by thermal ALD or plasma-enhanced ALD. The remaining thermal conductive layer is formed by a mode PE-ALD method. A metal organic source may be used as the metal source of the TaN, Ta, Cu, Al, Cr or Pt thermal conductive layer. The heat conductive layer has a thickness of about several tens of nm and is performed for about 60 minutes at a low temperature of 400 degrees or less. This limitation of temperature is inevitable for the protection of components already formed in the substrate and the nozzle plate.

According to the present invention, in the so-called back-shooting ink jet print head, a metal or metal nitride is formed on the inner wall of the chamber where ink can come into contact and heat concentration can occur and on the bottom of the restrictor, preferably the manifold and the substrate. A thermal conductive layer is formed. This structural feature effectively releases the heat present in the ink in the chamber and suppresses the adsorption of the dye present in the ink so that the heat from the heater can effectively contribute to the bubbles in the ink in the chamber. In addition, the physical rigidity of the thermally conductive layer protects the structure around the chamber from the impact generated when the bubble shrinks and disappears. Furthermore, hydrophilicity, which is one of the physical properties of the thermally conductive layer, allows the ink to flow more smoothly, thereby effectively supplying ink, filling, and the like.

For those skilled in the art, many changes and modifications are easy and obvious in light of the above-described preferred embodiments without departing from the spirit of the invention and the scope of the invention is more clearly pointed out by the appended claims. . It is to be understood that the disclosure and disclosure herein are merely exemplary and should not be understood as limiting the scope of the invention, which is pointed out in more detail by the appended claims.

Claims (9)

delete delete delete delete Forming a nozzle plate including a heater on an upper surface of the substrate; Forming a nozzle on the nozzle plate; A third step of forming an ink chamber on the substrate, the ink chamber being positioned below the heater provided on the nozzle plate and on which an inner surface of the nozzle plate is located; A fourth step of penetrating through the restrictor through which ink passes through the bottom of the ink chamber; And a fifth step of forming a thermally conductive layer on the inner wall of the restrictor and on the inner wall of the ink chamber and the inner surface of the nozzle plate located above the ink chamber by atomic layer deposition. Manufacturing method. The method of claim 5, wherein A step of forming an ink supply manifold corresponding to the ink chamber on the back surface of the substrate is further performed between the third step and the fourth step. Manufacturing method of an inkjet print head, characterized in that formed in the form of connecting. The method of claim 6, And the thermally conductive layer is formed on an inner surface of the manifold in the fifth step. The method according to any one of claims 5 to 7, And performing a bubble guide forming step extending from the nozzle to the chamber by a predetermined length between the second step and the third step, wherein the thermal conductive layer is formed like the surface of the bubble guide in the fifth step. A method of manufacturing an inkjet print head. The method of claim 8, The thermal conductive layer is any one selected from the group consisting of Ta, W, Cu, Al, Cr, Pt, TiN, TaN, Si ₃ N _{4 The} inkjet printhead manufacturing method.