KR20060125214A - Ink jet print head and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an ink jet print head and a method for manufacturing the same, characterized in that the two single crystal silicon substrates are integrally formed with a structure forming the ink jet print head using a micro process, and then bonded to each other.

According to the present invention, in the manufacturing process of the ink jet print head, the bonding process can be simplified, the alignment error caused by the bonding process can be reduced, and the product yield and performance can be improved.

Description

Ink jet print head and fabrication method

1 is a cross-sectional view of a conventional piezoelectric ink jet print head.

2 is a cross-sectional view of the ink jet print head of the present invention.

3 is a view showing a volume change state of the pressure chamber due to the deformation of the piezoelectric film.

4A-4I are cross-sectional views illustrating a method of forming a structure on a lower substrate of an ink jet print head of the present invention.

FIG. 5 is a view for explaining a state of the (100) plane and the (111) plane of a single crystal silicon substrate when wet etching with an anisotropic etching solution. FIG.

6 is a plan view of a lower substrate of the ink jet print head of the present invention.

7A to 7E are cross-sectional views illustrating a method of forming a structure on an upper substrate of an ink jet print head of the present invention.

8 is a view showing a state in which the upper substrate and the lower substrate of the ink jet print head of the present invention are bonded.

Explanation of symbols on the main parts of the drawings

100: lower substrate 110: nozzle

120: damper 130: channel

140: reservoir 200: upper substrate

210: ink inlet 220: pressure chamber

230: actuator 231: lower electrode

233: piezoelectric film 235: upper electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head and a method for manufacturing the same, and more particularly, to an ink jet print head and a method for manufacturing the same, in which microstructures of a single crystal silicon substrate are used to form the structures forming the ink jet print head.

Recently, due to the demands of the information age, technology has been remarkably developed in various fields such as display, recording media, and communication. In particular, in the case of printing technology, new and various technologies are being rapidly developed.

Among them, the inkjet printing technology is widely used for home, office and industrial use because of its simple structure and low price. The ink jet method is a method of printing by inserting ink into a fine nozzle (Nozzle) to the position to be printed using heat, bubbles or pressure.

In an ink jet printer, an ink jet print head is an important part, and an ink jet print head is used to print a predetermined color image by ejecting a small droplet of printing ink to a desired position on a recording sheet. Device.

Such ink jet print heads may be classified into heat-driven ink jet print heads and piezoelectric ink jet print heads according to ink ejection methods. Here, the thermally driven ink jet print head generates a bubble in the ink by using a heat source and ejects the ink by the expansion force of the bubble, and the piezoelectric ink jet print head uses a piezoelectric material to The ink is ejected by the pressure applied to the ink by deformation.

1 is a cross-sectional view of a conventional piezoelectric ink jet print head. As shown in the drawing, the first substrate 10 having the nozzle 10a for ejecting ink is formed on the first substrate 10 and the first ink outlet 11a and the ink container (not shown). A second substrate 11 having a reservoir 11b for storing ink flowing from the second substrate 11 and an upper portion of the second substrate 11 and having a second ink outlet 12a and a first ink inlet A third substrate 12 having a 12b), a fourth substrate 13 formed on the third substrate 12, and having a third ink outlet 13a and a second ink inlet 13b; It is formed on the fourth substrate 13 and is in communication with the third ink outlet 13a and the second ink inlet 13b, and the volume of the ink is changed by driving the actuator 20 to thereby eject or inject ink. A fifth substrate 14 having a pressure chamber 14a for generating a pressure change for the diaphragm, and a vibration plate 15 formed on the fifth substrate 14 and deformed by the actuator 20; The lower electrode 16, the piezoelectric film 17, and the upper electrode 18 are sequentially stacked on the diaphragm 15. Here, the lower electrode 16, the piezoelectric film 17, and the upper electrode 18 form an actuator 20 for generating a driving force for ejecting ink.

In the conventional piezoelectric inkjet printhead configured as described above, when a voltage is applied to the upper electrode 18 and the actuator 20 is driven, the diaphragm 15 is deformed by driving the actuator and the diaphragm 15 The volume of the pressure chamber 14a is reduced by the deformation of.

When the pressure in the pressure chamber 14a increases as the volume of the pressure chamber 14a decreases, the ink in the pressure chamber 14a is discharged from the third ink ejection opening 13a, the second ink ejection opening 12a, and the first ink. It moves to the nozzle 10a along the 1 ink ejection opening 11a, and is ejected from the said nozzle 10a.

When the voltage applied to the upper electrode 18 is removed, the diaphragm 15 is restored to its original shape and the volume of the pressure chamber 14a is increased. Then, when the pressure in the pressure chamber 14a decreases as the volume of the pressure chamber 14a increases, the ink stored in the reservoir 11a causes the first ink inlet 12b and the second ink inlet 13b to pass through. Through the pressure chamber 14a is introduced through.

The conventional piezoelectric ink jet print head is manufactured by alignment bonding in which each substrate is separately manufactured and then laminated and bonded to each other.

In the case of the alignment bonding of many substrates, there is a problem that the alignment error is increased due to the number of processes for aligning each substrate, and when the alignment error is increased, ink flow is not smooth and this causes a problem of lowering the resolution of the printer. Will be connected.

In addition, since the substrates are manufactured by different methods using different materials, the manufacturing process is complicated, and deformation may occur due to a difference in thermal expansion coefficient due to temperature change.

Accordingly, an object of the present invention is to provide an ink jet print head and a method of manufacturing the same, which can reduce the alignment error by simplifying the bonding process by integrally forming the structures forming the ink jet print head on two single crystal silicon substrates. .

An embodiment of the ink jet print head of the present invention is formed by penetrating an ink inlet through which ink is introduced, and having a pressure chamber for temporarily storing the ink to be ejected and pressurizing the stored ink to be ejected. An upper substrate having an actuator configured to transfer a driving force for ejecting the ink to the pressure chamber, an reservoir for storing ink flowing through the ink inlet, and supplying ink from the reservoir to the pressure chamber. A channel, a damper for transferring ink from the pressure chamber to the nozzle, and a nozzle for ejecting ink delivered from the damper are integrally formed, and the lower substrate is bonded to the upper substrate.

The upper substrate is a single crystal silicon substrate, and the lower substrate is characterized in that the surface is a (100) plane single crystal silicon substrate.

The actuator may include a lower electrode formed on an upper portion of the pressure chamber, a piezoelectric film formed on an upper portion of the lower electrode and causing deformation according to an applied voltage, and an upper portion formed on an upper portion of the piezoelectric film and applying voltage to the piezoelectric film. It is characterized by consisting of an electrode.

Here, the piezoelectric film is made of PZT (Plumbum-Zirconate-Titanate).

An embodiment of the method of manufacturing an ink jet print head of the present invention includes an ink inlet through which an ink is introduced by finely processing an upper substrate made of a single crystal silicon substrate, and pressure so that the ink to be ejected is temporarily stored and the stored ink is ejected. Forming a pressure chamber to apply, and forming an actuator on the upper portion of the pressure chamber to transmit a driving force for ejecting the ink to the pressure chamber, and finely processing a lower substrate made of a (100) plane single crystal silicon substrate. A reservoir for storing ink flowing through the ink inlet, a channel for supplying ink from the reservoir to the pressure chamber, a damper for transferring ink from the pressure chamber to the nozzle, and a nozzle for ejecting ink delivered from the damper Forming an upper substrate and the lower substrate; It characterized by that.

The forming of the damper, the nozzle, the channel, and the reservoir on the lower substrate may include forming a wet etching mask layer on the lower substrate and etching a portion of the wet etching mask layer to form the nozzle and the reservoir. Forming an opening for the substrate, wet etching the lower substrate exposed by the opening for forming the nozzle and the reservoir with an anisotropic etching solution, removing the wet etching mask layer, and then dry etching the lower substrate. Forming an opening for forming the damper by forming a mask layer for etching, etching a portion of the dry etching mask layer, and forming a lower substrate exposed by the opening for forming the damper. Dry etching to a predetermined depth with ion etching, forming a channel connecting the damper and the reservoir, and Dry etching the lower substrate exposed by the opening for forming until the nozzle is formed by Reactive Ion Etching (RIE), and removing the dry etching mask layer.

Here, the wet etching mask layer is preferably using Si ₃ N ₄ or SiO ₂ , the anisotropic etching solution is any one of EDP (Ethylenediamine Pyrocatechol Water), TMAH (Tetramethyl Ammonium Hydroxide), KOH (Potassium Hydroxide) Preference is given to using.

The forming of the pressure chamber and the ink inlet on the upper substrate may include forming an etching mask layer on the upper substrate and etching a portion of the etching mask layer to form an opening for forming the pressure chamber and the ink inlet. Forming a pressure chamber and an ink inlet by etching the upper substrate exposed by the opening for forming the pressure chamber and the ink inlet; and removing the etching mask layer. It is done.

Bonding of the upper substrate and the lower substrate is characterized in that it is carried out by any one of the method of bonding by epoxy or metal solder and Silicon Direct Bonding.

Hereinafter, an ink jet print head of the present invention and a manufacturing method thereof will be described in detail with reference to FIGS. 2 to 8. 2 is a cross-sectional view of the ink jet print head of the present invention.

As shown therein, the ink jet print head of the present invention includes an actuator 230, an upper substrate 200 in which the pressure chamber 220 and the ink inlet 210 are integrally formed, and a reservoir (reservoir) ( 140, the channel 130, the damper 120, and the lower substrate 100 on which the nozzles 110 are integrally formed are bonded to each other.

The upper substrate 200 may include an actuator 230 generating a driving force for ejecting ink from the nozzle 110, and the ink to be ejected may be temporarily stored, and the stored ink may be ejected by driving the actuator 230. It consists of a pressure chamber 220 for applying pressure and an ink inlet 210 through which ink is introduced from an ink container (not shown).

The lower substrate 100 may include a reservoir 140 in which ink flowing through the ink inlet 210 is stored, and ink in the pressure chamber 220 according to a pressure change of the pressure chamber 220. A damper 120 for transferring a pressure change and buffering a sudden pressure change, a channel 130 for supplying ink stored in the reservoir 140 to the pressure chamber 220, and the damper 120. It consists of a nozzle 110 for ejecting the ink to be delivered.

The actuator 230 includes a lower electrode 231 serving as a common electrode, a piezoelectric film 233 deformed according to an applied voltage, and an upper electrode 235 serving as a driving electrode.

In the ink jet print head of the present invention configured as described above, when a voltage is applied to the upper electrode 235 of the actuator 230, the piezoelectric film 233 causes deformation by piezoelectricity.

Here, piezoelectricity is represented by a combination of electrical and mechanical properties of a material, and when a deformation occurs by applying pressure to the material, an electric field is formed and a voltage is generated through the electrode, or when the electric field is applied to the piezoelectric material, deformation of the material is caused. The latter is the case here.

3 is a view showing a volume change state of the pressure chamber due to the deformation of the piezoelectric film. As shown in the drawing, when a voltage is applied to the upper electrode 235, the piezoelectric film 233 made of a piezoelectric material causes deformation, thereby reducing the volume of the pressure chamber 220 and thus, the pressure chamber ( The pressure in 220 will increase.

Energy generated as the pressure in the pressure chamber 220 increases is concentrated by the damper 120 to the nozzle 110, and the ink filled in the pressure chamber 220 passes through the damper 120 and passes through the nozzle 110. )

When the voltage applied to the upper electrode 235 is removed, the piezoelectric film 233 is restored to its original shape, thereby increasing the volume of the pressure chamber 220 and thus, the pressure in the pressure chamber 220. Will decrease.

When the pressure in the pressure chamber 220 decreases, ink stored in the reservoir 140 flows into the pressure chamber 220 through the channel 130.

The channel 130 not only serves as a passage for supplying ink from the reservoir 140 to the pressure chamber 220, but also when the ink is ejected from the nozzle 110, the reservoir 130 is discharged from the pressure chamber 220. 140) prevents ink from flowing back.

4A to 4I are cross-sectional views illustrating a method of forming a structure on a lower substrate of the ink jet print head of the present invention. As shown in FIG. 4, first, wet etching mask layers 301a and 301b are deposited on both surfaces of the lower substrate 300 (FIG. 4A).

Here, the lower substrate 300 uses a (100) plane single crystal silicon wafer, and the lower substrate 300 preferably has a thickness of 200 to 250 μm. The wet etching mask layers 301a and 301b may be formed of a Si ₃ N ₄ or SiO ₂ layer.

Subsequently, a pattern is formed on a portion 305 for forming a nozzle and a portion 307 for forming a reservoir using a lithography process on the lower substrate 300 and the wet etching mask using a dry etching process. The layer 301a is removed (FIG. 4B).

Next, a wet etching process is performed on the portion 305 to form the nozzle and the portion 307 to form the reservoir using an anisotropic etching solution (FIG. 4C). The single crystal silicon wafer may be prepared using a solution that exhibits anisotropic etching characteristics for the (100) and (111) planes, for example, Ethylenediamine Pyrocatechol Water (EDP), Tetramethyl Ammonium Hydroxide (TMAH), and Potassium Hydroxide (KOH). Three-dimensional microstructures of shape and size can be produced.

When the (100) plane single crystal silicon substrate is used as the lower substrate 300, a microstructure having a square pyramid shape is formed by using the anisotropic wet etching characteristics of the (100) and (111) planes of the lower substrate 300. can do.

That is, since the etching speed of the (111) plane of the single crystal silicon wafer is considerably slower than that of the (100) plane, the lower substrate 300 is inclinedly etched along the (111) plane to form a square pyramid-like microstructure. Will form.

In this case, the (111) plane of the single crystal silicon wafer has an inclination of 54.74 ° with the (100) plane of the single crystal silicon wafer, as shown in FIG. 5.

Through the wet etching process, the portion 305 to form the nozzle of the ink jet print head has a square pyramid shape where the (111) planes of silicon meet with the (100) planes at an inclination of 54.74 °, respectively, to form a reservoir. The portion 307 has a wider pattern width than the portion 305 to form the nozzle and has a trapezoidal shape having a narrow bottom surface. At this time, the reservoir 309 is formed having a depth of 150 ~ 180 ㎛.

Subsequently, the wet etching mask layers 301a and 301b are removed and the lower substrate 300 is placed in a furnace at about 1100 ° C. to form silicon oxide layers (SiO ₂ ) on both sides of the lower substrate 300. ) 310a and 310b are grown (FIG. 4D). The silicon oxide layer (SiO ₂ ) 310a and 310b may serve as a mask layer for dry etching.

Next, a part of forming a nozzle of the ink jet head by applying a photoresist on the silicon oxide layer 310a formed on the lower substrate 300 and patterning the applied photoresist PR. An opening is formed in 305.

Then, the silicon oxide layer 310a of the portion exposed through the opening is removed by dry or wet etching using the photoresist as an etch mask to expose a portion 305 to form a nozzle, and then strip the photoresist. (FIG. 4E).

Subsequently, the portion 305 to form the nozzle is dry-etched by Reactive Ion Etching (RIE) (FIG. 4F). When performing the above RIE, it is preferable to use Sf ₆ , O ₂ and CHF ₃ gas.

In the case of the RIE, the portion 305 where the nozzle is formed is etched in a direction perpendicular to the shape while maintaining the shape formed through the anisotropic wet etching because the RIE is etched with straightness. Through the dry etching process, a damper 311 is formed to transfer the ink in the pressure chamber (not shown) to the nozzle.

Next, after etching of a predetermined depth through the dry etching, a channel 313 for connecting the reservoir 309 of the ink jet print head and the damper 311 formed through the dry etching process is formed (FIG. 4g). That is, photoresist is applied on the silicon oxide layer 310a, and the applied photoresist is patterned to form an opening in a portion to form a channel.

The exposed portion of the channel is formed by dry or wet etching the silicon oxide layer 310a of the portion exposed through the opening using the photoresist as an etching mask, and then dry or wet etching the exposed portion. Channel 313 is formed.

Subsequently, the dry etching process is continued to form a shape, that is, a trapezoidal end portion of the portion to form the nozzle, meets the silicon oxide layer 310b formed on the bottom surface of the lower substrate 300 to form a nozzle. It proceeds until 315 is formed (FIG. 4H).

In this case, the silicon oxide layer 310b formed on the bottom surface of the lower substrate 300 functions as an etch stop layer, and the size of the nozzle 315 may be adjusted by a time for performing a dry etching process. In addition, it is preferable to adjust the dry etching process so that the diameter of the nozzle 315 is about 18 to 22 μm.

Finally, the remaining silicon oxide film layers 310a and 310b are removed by wet etching or the like (FIG. 4I). Through such a manufacturing process, the reservoir 309 in which the ink is stored in the lower substrate 300 and the ink in the pressure chamber are transferred to the nozzle 315 according to the pressure change of the pressure chamber (not shown), and the sudden pressure change is performed. A damper 311 for buffering the pressure, a channel 313 connecting the reservoir 309 and the damper 311, and a nozzle 315 for ejecting ink delivered by the damper 311. Can be formed.

6 is a plan view of the lower substrate of the ink jet print head of the present invention. As shown therein, the lower substrate 400 has a trapezoidal reservoir 410 having a slope of 54.74 ° and a narrow bottom surface thereof, and formed on the reservoir 410 on one side of the horizontal side of the reservoir 410. One end of channels 420 is formed to supply stored ink to a damper (not shown).

The other end of each channel 420 is connected to a damper, and a nozzle 430 for ejecting ink is formed under the damper. For reference, the damper is not displayed since the drawing is a plan view. The nozzle 430 has a quadrangular pyramid in which the (111) plane of the lower substrate 400 has an inclination of 54.74 ° with the (100) plane.

7A to 7E are cross-sectional views illustrating a method of forming a structure on an upper substrate of an ink jet print head of the present invention. As shown in FIG. 7, first, silicon oxide layers (SiO ₂ ) 510a and 510b are grown on both surfaces of the upper substrate 500 (FIG. 7A).

Here, the upper substrate 500 is made of a single crystal silicon substrate, the thickness is preferably about 100 ~ 130 ㎛.

Next, a photoresist PR is applied to a surface of the silicon oxide layer 510b formed on the bottom surface of the upper substrate 500, and the applied photoresist PR is patterned to form a pressure chamber and an ink inlet of the ink jet print head. Openings are formed in the portions 501 and 502 to be formed.

In addition, the silicon oxide layer 510b of the portion exposed through the opening is removed by dry or wet etching using the photoresist as an etching mask to form the pressure chamber and the ink inlet (501, 502). Is exposed (FIG. 7B).

Thereafter, the exposed portions 501 and 502 are etched using the photoresist as an etch mask to form a pressure chamber 505 and an ink inlet 507 (FIG. 7C). At this time, the depth of the pressure chamber is preferably about 50 ~ 80 ㎛, the upper substrate on the pressure chamber 505 serves as a diaphragm.

Next, the remaining silicon oxide layer (SiO ₂ ) 510a and 510b is removed using a wet or dry etching process (FIG. 7D).

Subsequently, the actuator 517 is formed by sequentially stacking the lower electrode 511, the piezoelectric film 513, and the upper electrode 515 in the upper region where the pressure chamber 505 of the upper substrate 500 is formed (FIG. 7e).

The lower electrode 511 and the upper electrode 515 are preferably formed by sputtering Pt to a predetermined thickness, and the piezoelectric film 513 may be formed of a piezoelectric material. PZT (Plumbum-Zirconate-Titanate) is preferably used. The PZT can be made relatively large with low voltage supply.

Up to this point, the process of forming a structure on the lower substrate and the upper substrate of the ink jet print head of the present invention has been described. Finally, as shown in FIG. 8, the lower substrate 700 and the upper substrate 600 are described. Perform the process of bonding.

For bonding the lower substrate 700 and the upper substrate 600, an epoxy or metal solder and silicon direct bonding method may be used.

Here, the bonding using epoxy is to bond the lower substrate 700 and the upper substrate 600 through a polymer bonding agent, and the bonding using metal solder is any one of the lower substrate 700 and the upper substrate 600. The lower substrate 700 and the upper substrate 600 are bonded to each other by applying a low melting point metal and applying heat thereto.

In the silicon direct bonding method, first, the lower substrate 700 and the upper substrate 600 are surface treated, and then put in an oxide furnace to form an oxide film on the surface thereof. The lower substrate 700 and the upper substrate 600 are aligned and stacked, and then bonded by annealing in an horizontal direction.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and variations of the present invention without departing from the spirit or field of the invention provided by the claims below It will be readily apparent to one of ordinary skill in the art that it can be used.

According to the present invention, by integrally forming the structures forming the ink jet print head using two single crystal silicon substrates and then bonding them, it is possible to simplify the bonding process of the ink jet print head, alignment according to the bonding process The error can be reduced.

In addition, by using the substrate of the same material, thermal deformation hardly occurs, and the yield of the product can be improved.

Claims (12)

It is formed through the ink inlet through which the ink flows, and has a pressure chamber for applying the pressure so that the ink to be ejected is temporarily stored and the stored ink is ejected, and a driving force for ejecting the ink on top of the pressure chamber An upper substrate on which an actuator for transferring to the pressure chamber is formed; And A reservoir for storing ink flowing through the ink inlet, a channel for supplying ink from the reservoir to the pressure chamber, a damper for transferring ink from the pressure chamber to the nozzle, and ejecting ink received from the damper An ink jet print head comprising a lower substrate integrally formed with a nozzle and bonded to the upper substrate. An ink jet print head according to claim 1, wherein the upper substrate is a single crystal silicon substrate, and the lower substrate is a (100) plane single crystal silicon substrate. The apparatus of claim 1, wherein the actuator; A lower electrode formed on the pressure chamber; A piezoelectric film formed on the lower electrode and causing deformation according to an applied voltage; And And an upper electrode formed on the piezoelectric film and configured to apply a voltage to the piezoelectric film. 4. An ink jet print head according to claim 3, wherein the piezoelectric film is made of PZT (Plumbum-Zirconate-Titanate). The ink jet print head of claim 1, wherein the nozzle has a size of 18 to 22 μm. The upper substrate made of a single crystal silicon substrate is finely processed to form an ink inlet through which ink is introduced, and a pressure chamber configured to apply pressure to allow the ink to be ejected to be temporarily stored and the stored ink to be ejected, and the ink above the pressure chamber. Forming an actuator for transmitting a driving force to eject the pressure to the pressure chamber; A reservoir for storing the ink flowing through the ink inlet by finely processing a lower substrate made of a (100) plane single crystal silicon substrate, a channel for supplying ink from the reservoir to the pressure chamber, and nozzles for ink from the pressure chamber. Forming a damper for transferring the nozzle to a nozzle for ejecting ink transferred from the damper; And An ink jet printhead manufacturing method comprising the step of bonding the upper substrate and the lower substrate. The method of claim 6, wherein forming a damper, a nozzle, a channel, and a reservoir in the lower substrate; Forming a wet etching mask layer on the lower substrate; Etching a portion of the wet etching mask layer to form an opening for forming the nozzle and the reservoir; Wet etching the lower substrate exposed by the opening for forming the nozzle and reservoir with an anisotropic etching solution; Removing the wet etching mask layer, and then forming a dry etching mask layer on the lower substrate; Etching a portion of the dry etching mask layer to form an opening for forming the damper; Dry etching the lower substrate exposed by the opening for forming the damper to a predetermined depth with Reactive Ion Etching (RIE); Forming a channel connecting the damper and a reservoir; Dry etching the lower substrate exposed by the opening for forming the damper until the nozzle is formed by reactive ion etching (RIE); And Inkjet print head manufacturing method comprising the step of removing the dry etching mask layer. The method of claim 7, wherein the wet etching mask layer is any one of Si ₃ N ₄ or SiO ₂ . The method of claim 7, wherein the anisotropic etching solution is any one of Ethylenediamine Pyrocatechol Water (EDP), Tetramethyl Ammonium Hydroxide (TMAH), Potassium Hydroxide (KOH). The method of claim 7, wherein the dry etching mask layer is SiO ₂ . The method of claim 6, wherein forming a pressure chamber and an ink inlet in the upper substrate; Forming an etching mask layer on the upper substrate; Etching a portion of the etching mask layer to form an opening for forming the pressure chamber and the ink inlet; Etching the upper substrate exposed by the opening for forming the pressure chamber and the ink inlet to form the pressure chamber and the ink inlet; And The method of claim 1, wherein the etching mask layer is removed. The method of claim 6, wherein the bonding between the upper substrate and the lower substrate is performed by any one of an epoxy or metal solder bonding method and a silicon direct bonding method. .

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