JP5059227B2 - Discharge head manufacturing method - Google Patents

Description

  The present invention relates to an ejection head that ejects liquid droplets as typified by an ink jet recording method and landes the liquid droplets on an ejection target, an ejection apparatus using the ejection head, and a method for manufacturing the ejection head.

  A discharge device for discharging a small amount of droplets is called a so-called ink jet device, and is used to manufacture image recording (formation) such as a printer, a facsimile, a copying apparatus, and a plotter, a liquid crystal device, and other electronic devices. It is used for. In recent years, as described in Japanese Patent Publication No. 2000-270896 and PCT Publication No. WO95 / 25116, it has also been applied to ink jets for microarray production methods for comprehensive analysis of biological materials.

  The discharge head includes at least a nozzle hole for discharging droplets, a liquid chamber connected to the nozzle hole for storing discharge liquid, and a pressure mechanism for applying pressure to the liquid chamber. By operating the mechanism and pressurizing the discharge liquid filled in the liquid chamber, droplets are discharged from the opening of the nozzle hole.

  As the base material for forming the nozzle holes, inorganic materials such as stainless steel (SUS), nickel and silicon, and resin materials such as polyimide and polysulfone are used.

In addition to using the base material alone as described above, in order to improve the accuracy of the opening portion of the nozzle hole, the base material may have a two-layer structure of a layer that maintains the hole diameter accuracy and a layer that maintains high rigidity. (Japanese Patent Laid-Open No. 10-119300).
As processing means for forming the nozzle holes, means such as punching, wet etching, dry etching, laser processing, electroforming, and the like are used.

  As a pressure mechanism for applying pressure to the liquid chamber, an energy generation means (actuator element) including an electromechanical conversion element such as a piezoelectric element, an electrothermal conversion element such as a heater, and an electrostatic force generation means such as an electrode is used. ing. In the case of a printer, in order to eject a droplet from a nozzle hole at a position corresponding to image information, by operating a pressure mechanism provided in the nozzle hole, from the nozzle hole at a position where the droplet should be ejected, The discharge liquid is discharged as droplets.

  The amount of liquid droplets as described above is not only affected by the shape and size of the opening of the nozzle hole but also discharged from the nozzle hole when the discharge liquid adheres to the surface of the discharge head. When the liquid comes into contact with the ejected liquid adhering to the surface of the ejection head, inconveniences such as a change in the ejecting direction and the amount of the ejected liquid droplets occur.

  Therefore, even in the prior art, a nozzle-hole is formed by forming a liquid-repellent (liquid-repellent and ink-repellent) thin film on the surface where the nozzle hole opening of the ejection head is located, or by applying a surface treatment to impart liquid-repellent properties. A technique is known in which the discharge liquid does not adhere to the vicinity of the opening.

  For example, a method of applying a silicon-based or fluorine-based liquid repellent (Japanese Patent Laid-Open Nos. 55-65564 and 9-76512), and a method of performing surface treatment using a silane coupling agent containing fluorocarbon ( JP-A-56-89569, JP-A-10-176139), a method for forming a liquid-repellent film by plasma polymerization of a fluorine compound or a silane compound (see JP-A 64-87359), fluorine There are methods for forming a liquid-repellent film of a polymer (JP-A-7-125220, JP-A-8-244235, JP-A-2002-20697), and the like.

However, several problems have arisen with the high integration of the droplet discharge head and the high accuracy of the droplet discharge position.
It is difficult to satisfy the required accuracy when a punching method such as punching or electroforming is used as a processing means for a nozzle hole which is a droplet discharge port. Laser drilling achieves high-precision machining, but practical substrates are limited to resin members such as polyimide.

However, when the resin base material is used, since the rigidity is low, the pressure fluctuation in the liquid chamber is absorbed, and the injection efficiency is lowered, resulting in discharge failure.
When an object bonded to a base material having high rigidity is used as the droplet discharge head, the position accuracy of the discharge port is reduced when each base material is assembled.

  On the other hand, when liquid repellency is imparted to the surface of the ejection head, it is difficult to obtain coatability, adhesion, mechanical durability, and chemical alteration with conventional monomolecular films and thin films. It becomes necessary.

  In addition, when forming a spacer formation for a liquid crystal panel, a discharge liquid in which spacer particles are dispersed in an aqueous solvent is used. When such a discharge liquid is used, it adheres to the surface when wiping and cleaning the discharge head. The ejected head may be rubbed and damaged by the spacer particles.

  A discharge head used for such an application is required to have a particularly high mechanical strength. However, no conventional discharge head has a sufficient mechanical strength for such an application.

JP 2000-270896 A International Publication No. 95/25116 JP-A-10-119300 JP 55-65564 A JP-A-9-76512 JP-A-56-89569 JP-A-10-176139 JP-A 64-87359 JP-A-7-125220 JP-A-8-244235 JP 2002-20697 A

  The present invention provides an ejection head capable of ejecting droplets with high accuracy over a long period of time, an ejection apparatus using the ejection head, and a method for manufacturing the ejection head.

In order to solve the above-mentioned problems, the present invention forms a diamond thin film on the surface of a silicon substrate, forms an inorganic resist film on the surface of the diamond thin film, forms a first opening in the inorganic resist film, Forming a second opening communicating with the first opening in the diamond thin film, etching the surface of the silicon substrate exposed on the bottom surfaces of the first and second openings using the inorganic resist film as a mask; After forming the bottomed small hole in the silicon substrate, the bottom surface of the bottom surface of the bottom of the bottomed small hole is larger than the bottom surface of the bottomed small hole by etching a portion of the back side of the bottom of the silicon substrate to the middle of the bottomed small hole. And forming a nozzle hole by opening the bottom end of the bottomed small hole in the bottom surface of the discharge liquid chamber, and after forming a base oxide film in the nozzle hole and the discharge liquid chamber by thermal oxidation, Serial inorganic resist film is removed, a discharge head manufacturing method for manufacturing an ejection head in which the diamond thin film disposed on the surface.
The present invention is a method for manufacturing an ejection head, wherein when the first opening is formed, a patterned first organic resist film is formed on a surface of the inorganic resist film, and the first organic resist film is formed. Removing the portion of the inorganic resist film exposed at the bottom of the first resist opening to form the first opening in the inorganic resist film, and forming the second opening, After the organic resist film is removed, the portion of the diamond thin film exposed on the bottom surface of the first opening is removed to form the second opening in the diamond thin film.
The present invention is a method for manufacturing an ejection head, wherein after the first organic resist film is removed, a second organic resist film in which a second resist opening is disposed on the first opening is used as the inorganic resist. A portion of the silicon substrate that is exposed on the bottom surface of the first opening is disposed in the depth direction with the second resist opening and the first and second openings being in communication with each other. This is a discharge head manufacturing method in which the bottomed small holes are formed by etching away leaving the bottom.

In the present invention, the diamond thin film includes a diamond-like carbon thin film.
The present invention is configured as described above, and a diamond thin film is formed on the surface of the ejection head. The diamond thin film has higher mechanical strength than the constituent material of the discharge head and is chemically stable.

Therefore, the discharge head of the present invention has high durability, and by providing this diamond thin film as a liquid repellent coating, it is possible to provide a stable droplet discharge nozzle.
Die Ya Monde thin film, it is possible to easily manufacture By using means of conventional chemical vapor deposition method.

Further, the die Ya Mondo thin film since it is possible Plasma etching with a mixed gas or other gas of Ar and oxygen, fine processing can be easily realized. Therefore, after forming the diamond thin film on the surface of the inorganic substrate, the nozzle holes and the discharge liquid chamber can be formed by etching.

  The inner wall surface of the nozzle hole and the inner wall surface of the discharge liquid chamber need to be more lyophilic with respect to the discharge liquid than the diamond thin film. This is because the discharge liquid needs to be filled up to the vicinity of the discharge port in order to increase the discharge accuracy of the discharge liquid.

Since the oxide is more hydrophilic than diamond, when the discharge liquid contains water, the lyophilicity is enhanced by exposing the oxide to the inner wall of the discharge liquid chamber and the inner wall of the nozzle hole.
When the inorganic substrate on which the discharge liquid chamber and the nozzle hole are formed is made of an oxide (for example, glass), it is only necessary to expose the inner wall surface of the discharge liquid chamber and the nozzle hole.

When the inorganic substrate is made of a material other than oxide (for example, silicon), an oxide film is formed on the inner wall surface of the discharge liquid chamber and the inner wall surface of the nozzle hole, or the inner wall surface of the discharge liquid chamber and the nozzle Hydrophilicity can be increased by oxidizing the inner wall surface of the hole.
As a result, it is possible to create a nozzle plate that sufficiently satisfies the positional accuracy and droplet characteristics of the ejected droplets.

  In the present invention, since the rigid base material is used, the positional accuracy of the nozzle holes is high. Further, since the discharge head can be formed of a material having rigidity, durability is high. Since a diamond thin film is formed on the surface where the nozzle hole is located, durability is high. Since the nozzle holes are filled with the discharge liquid and the discharge liquid does not spread on the surface of the diamond thin film, the discharge accuracy is high.

Sectional drawing for demonstrating the 1st example of the discharge apparatus of this invention The top view for demonstrating the 1st example of the discharge apparatus of this invention The top view for demonstrating the discharge apparatus of a 2nd example Sectional drawing for demonstrating an example of the discharge head of this invention (A): sectional view taken along line II in FIG. 4, (b): plan view of the ejection head of the present invention. (A)-(f): Sectional drawing for demonstrating the first half of the manufacturing process of a 1st example. (G)-(j): Sectional drawing for demonstrating the second half of the manufacturing process of a 1st example. (A)-(f): Sectional drawing for demonstrating the first half of the manufacturing process of a 2nd example.

Reference numeral 10 in FIGS. 1 to 3 is an example of a discharge device according to the present invention, and a shaft 12 is disposed on a table 11. A plurality of ejection heads 20 are provided on the shaft 12.
FIG. 4 is a schematic cross-sectional view of the discharge head 20 and has a plurality of discharge liquid chambers 21.

  A nozzle hole 22 having a diameter of 20 μm is formed on the bottom surface of each discharge liquid chamber 21, and the inside of the discharge liquid chamber 21 is connected to the external atmosphere of the discharge head 20 through the nozzle hole 22.

FIG. 5B is a plan view of the surface of the discharge head 20 where the opening (discharge port 23) of the nozzle hole 22 is located, and FIG. 5A is a cross-sectional view taken along line II of the discharge head 20. FIG. . 4 corresponds to a cross-sectional view taken along line AA ′ of FIG.
As shown in FIG. 1, each ejection head 20 has a surface on which the ejection port 23 is positioned facing the surface of the base 11 of the ejection apparatus 10.

  As shown in FIG. 2, the discharge head 20 is connected to the discharge liquid supply device 13, and the discharge liquid supplied from the discharge liquid supply device 13 is connected to the discharge liquid chamber 21 of each discharge head 20 shown in FIG. It is comprised so that the inside of the nozzle hole 22 may be filled.

  A pressure device (not shown) is provided in each of the discharge liquid chambers 21. When the pressure device in the discharge liquid chamber 21 at a desired position is operated, the discharge liquid in the discharge liquid chamber 21 is discharged into the nozzle hole 22. The liquid is discharged toward the surface of the table 11 through.

A processing object 14 (here, a glass substrate) is arranged on the table 11 of the discharge device 10 shown in FIG. 1, and the discharged discharge liquid lands on the surface of the processing object 14.
In FIG. 2, the shaft 12 and the processing target 14 are configured to be relatively movable (here, the shaft 12 moves), and the discharge head 20 is processed at a position directly above the processing target 14. It is configured to face the object 14 and land the discharge liquid at a desired position of the processing object 14.

  If the distance between the desired positions of the processing object 14 and the distance between the nozzle holes 22 are different, the shaft 12 may be inclined so that the nozzle holes 22 pass over the desired position, as shown in FIG. .

As shown in FIG. 4, a diamond thin film 32 is formed on the surface where the discharge port 23 of the discharge head 20 is located.
Die Ya Monde, carbon atoms with adjacent mutually share electrons, are physically and chemically very stable in that it is rigidly coupled, have a high resistance to mechanical abrasion and chemical modification .

  Further, since the diamond thin film has higher liquid repellency than the inorganic substrate used for manufacturing the discharge head 20 such as a silicon substrate or a glass substrate, the discharge liquid contracts in a spherical shape due to surface tension and spreads on the surface of the diamond thin film 32. I don't get it. Accordingly, the discharge liquid does not adhere to the surface of the discharge head 20.

Next, the manufacturing process of the ejection head 20 will be described.
<Production process of the first example>
Reference numeral 30 in FIG. 6A indicates an inorganic substrate made of a silicon substrate, a glass substrate, or the like.

As shown in FIG. 6A, a diamond thin film 32 is formed on the surface of the inorganic substrate 30 by a CVD method. Then, as shown in FIG. 6B, an inorganic resist film 36 is formed on the surface of the diamond thin film 32. Deploy. Here, the inorganic resist film 36 is a SiO ₂ film and is formed by a CVD method.

Next, a patterned organic resist film 38 is disposed on the surface of the inorganic resist film 36 as shown in FIG.
The organic resist film 38 is formed, for example, by patterning a photosensitive resin layer formed on the surface of the inorganic resist film 36 by a lithography method.

  In the organic resist film 38, an opening 39 is formed at a position where the nozzle hole 22 is formed, and the inorganic resist film 36 on the bottom surface of the opening 39 is removed by a dry etching apparatus, and as shown in FIG. When the inorganic resist film 36 is patterned in the same shape as the organic resist film 38, the organic resist film 38 is removed, and then the diamond thin film 32 exposed on the bottom surface of the opening 37 of the inorganic resist film 36 is etched by dry etching. ), The diamond thin film 32 has an opening 33 at a position where the nozzle hole 22 is formed.

  Next, as shown in FIG. 5F, an organic resist film 26 having an opening is formed on the surface of the inorganic resist film 36 on the opening 33 of the diamond thin film 32, and the opening 33 and the inorganic resist film of the diamond thin film 32 are formed. The opening 37 of the 36 and the opening of the organic resist film 26 are communicated.

  Reference numeral 27 in FIG. 7 (f) denotes a communicating opening. When the inorganic substrate 30 exposed on the bottom surface of the opening 27 is etched by dry etching and the organic resist film 26 is removed, as shown in FIG. 7 (g). A bottomed small hole 42 is formed.

  Next, as shown in FIG. 7 (h), an organic resist film 28 having an opening 29 at the position of the discharge liquid chamber 21 is formed on the back surface of the inorganic substrate 30 in this state, etched, and then etched (i). ), A bottomed discharge liquid chamber 21 is formed. The bottom surface of the discharge liquid chamber 21 reaches the bottom surface of the small hole 42, the inside of the small hole 42 communicates with the discharge liquid chamber 21, and the nozzle hole 22 is formed by the remaining portion of the small hole 42. Reference numeral 60 in FIG. 6I denotes a head body in a state where the nozzle holes 22 and the discharge liquid chamber 21 are formed in the inorganic substrate 30.

The head main body 60 is carried into a thermal oxidation furnace with the surface on which the discharge liquid chamber 21 is formed exposed, the head main body 60 is thermally oxidized (thermal oxidation method), and the nozzle holes 22 and the discharge liquid chamber 21 inside. After forming a base oxide film (here, a 100 nm-thickness silicon oxide film, SiO ₂ film) 31, the inorganic resist film 36 on the surface of the diamond thin film 32 is removed, and as shown in FIG. When the panel 70 is attached and the opening of the discharge liquid chamber 21 opposite to the nozzle hole 22 is closed, the discharge head 20 is obtained.

  The above describes the case where the nozzle hole 22 and the discharge liquid chamber 21 are formed after the diamond thin film 32 is formed on the surface of the inorganic substrate 30, but the present invention is not limited to this.

Below, the manufacturing method of this invention 2 example is demonstrated.
<Manufacturing process of the second example>
First, the discharge liquid chamber resist film 50 made of a silicon thin film is formed on one surface of the inorganic substrate 30 by sputtering, and the single-side discharge liquid chamber resist film 50 is patterned to form the discharge liquid chamber 21. Place an opening at the position. When the inorganic substrate 30 is a glass substrate, it is immersed in a buffered hydrofluoric acid solution and isotropic wet etching is performed to form the discharge liquid chamber 21 (FIG. 8A). In this case, the opposite surface of the inorganic substrate 30 covers and protects the resin film 4 9, after the wet etching to remove the resin film 49. .

  Next, after immersing in a tetramethylammonium hydroxide solution to remove the discharge liquid chamber resist film 50 made of a silicon thin film, an organic resist film is formed on the surface opposite to the discharge liquid chamber 21, and the organic resist The film is patterned by lithography to form a nozzle hole resist film 40 (FIG. 8B).

  The nozzle hole resist film 40 has an opening directly behind the discharge liquid chamber 21, and when the nozzle hole 22 is formed by performing anisotropic etching by a dry process using the nozzle hole resist film 40 as a mask, A head main body 60 as shown in FIG. 8C is obtained.

Next, the nozzle hole resist film 40 is removed, and a diamond thin film 32 is formed on the surface of the head body 60 on the side where the nozzle holes 22 are located.
When the diamond thin film 32 is formed, if the plasma-formed source gas (methane gas or hydrogen gas) enters the inside of the nozzle hole 22 or the inside of the discharge liquid chamber 21, the diamond thin film 32 is inside the nozzle hole 22 or the discharge liquid chamber 21. They are also formed inside (FIG . 8D) .

The diamond thin film 32 is formed in order to remove the diamond thin film 32 inside the nozzle hole 22 and the discharge liquid chamber 21 while leaving the diamond thin film 32 on the surface of the head body 60 where the nozzle hole 22 is formed. The head main body 60 is carried into the vacuum chamber of the etching apparatus, the surface of the head main body 60 is placed in close contact with the table, the inside of the discharge liquid chamber 21 faces upward, and oxygen gas is introduced into the vacuum chamber. When the oxygen gas plasma is generated, the diamond thin film 32 formed in the discharge liquid chamber 21 and the nozzle hole 22 comes into contact with the plasma, and the excess diamond thin film 32 is removed. At this time, the diamond thin film 32 on the surface of the head main body 60 remains without being in contact with the plasma (FIG. 8E).

  When the inorganic substrate 30 is composed of a silicon substrate, after forming the discharge liquid chamber 21 and the nozzle hole 22, before forming the diamond thin film 32, or after forming the diamond thin film 32, It is desirable to form the base oxide film 31 by performing the same thermal oxidation process as in the manufacturing process.

  The base oxide film 31 is also formed on the front and back surfaces of the head main body 60 and the inner surfaces of the discharge liquid chamber 21 and the nozzle hole 22, and is not removed by plasma when the diamond thin film 32 is removed. It remains on the inner surface of the liquid chamber 21 and the inner surface of the nozzle hole 22 to maintain lyophilicity.

After removing the excessive diamond thin film 32 of the head body 60, for example, ultrasonic cleaning is performed using Novec HFE7100 (registered trademark) manufactured by Sumitomo 3M, and then the back panel 70 is attached to close the discharge liquid chamber 21. The discharge head 80 is obtained (FIG. 8 (f)) .

<Example 1>
The ejection head 20 of Example 1 was manufactured by the manufacturing process of the first example described above under the conditions shown below.

Inorganic substrate 30: Silicon substrate with a film thickness of 0.2 mm Diamond thin film 32: Film thickness of 150 nm (CVD method)
Inorganic resist film 36: 300 nm thick SiO ₂ thin film (CVD method)
Base oxide film 31: film thickness 100 nm
Nozzle hole 22: φ20μm
The diamond thin film 32 is a non-patent document: Physical Status Solid (a) (2006) 203, No. 13,3245-3272 as described, and plasma gas mixture of methane and hydrogen, the die Ya Mondo was performed by using a CVD method where crystal growth of an inorganic substrate 30 surface.

The patterning of the inorganic resist film 36, the diamond thin film 32, and the inorganic substrate 30 is dry etching using an etching gas. As the etching gas, a mixed gas of Ar and CF ₄ was used for patterning the inorganic resist film 36, a mixed gas of Ar and O ₂ was used for patterning the diamond thin film 32, and a CF ₆ gas was used for patterning the inorganic substrate 30. The discharge liquid chamber 21 was formed by dry etching anisotropic etching.

  When evaluation was performed by dropping 3 pL of ink at a time using the ejection head of Example 1, sufficient positional accuracy and ejection amount accuracy could be obtained. In addition, superiority with respect to wear over time is recognized over the conventional one.

<Example 2>
The ejection head 80 of Example 2 was manufactured by the manufacturing process of the second example described above under the conditions shown below.

Inorganic substrate 30: glass substrate, Pyrex (code 7740) (registered trademark: manufactured by Corning International Co., Ltd.), film thickness 0.15 mm
Nozzle hole 22: φ30μm
Diamond thin film 32: film thickness 200 nm (CVD method)
The diamond thin film 32 was formed under the same conditions as in Example 1 above. The formation of the nozzle hole 22 and the removal of the excess diamond thin film 32 are each dry etching using an etching gas. As the etching gas, a mixed gas of Ar and CF ₄ was used for forming the nozzle hole 22, and a mixed gas of Ar and O ₂ was used for removing the diamond thin film 32.

  When evaluation was performed by dropping 5 pL of ink at a time using the ejection head 80 of Example 2, sufficient positional accuracy and ejection amount accuracy could be obtained. In addition, superiority with respect to wear over time is recognized over the conventional one.

<Other embodiments>
In addition to the silicon substrate and Pyrex glass described above, the inorganic substrate 30 of the present invention includes quartz glass such as Pycor Glass (registered trademark), ULE (registered trademark), Eagle 2000 (registered trademark), and TEMPAX FLOAT (registered trademark). An inorganic material such as silicon nitride can be used.

  The etching method for forming the discharge liquid chamber 21 and the nozzle hole 22 in the inorganic substrate 30 is not particularly limited, and either a wet process or a dry process can be used.

The combination of the kind of the inorganic substrate 30 and the manufacturing steps of the first and second examples is not particularly limited. For example, the discharge head 20 may be manufactured in the manufacturing step of the second example using a silicon substrate, The discharge head 80 may be manufactured by the manufacturing process of the first example using a glass substrate.
The nozzle hole 22 can be formed by wet etching or etching by a dry process.

The method for forming the diamond thin film 32 is not particularly limited, but contains at least one hydrocarbon gas selected from a hydrocarbon gas group consisting of CH ₄ , C ₆ H ₆ , and C ₂ H _2, and is necessary. Accordingly, the film can be formed by a CVD method in which a source gas to which an additive gas such as H ₂ gas is added is turned into plasma.

  The above has described the discharge heads 20 and 80 in which the nozzle hole 22 and the discharge liquid chamber 21 are integrated. However, the structure is not particularly limited as long as at least the nozzle hole 22 is formed.

  DESCRIPTION OF SYMBOLS 10 ... Discharge device 20, 80 ... Discharge head 21 ... Discharge liquid chamber 22 ... Nozzle hole 23 ... Discharge port 30 ... Inorganic substrate 32 ... Diamond thin film 60 ... Head main body

Claims (3)

A diamond thin film is formed on the surface of a silicon substrate,
Forming an inorganic resist film on the surface of the diamond thin film;
Forming a first opening in the inorganic resist film;
Forming a second opening communicating with the first opening in the diamond thin film;
After etching the surface of the silicon substrate exposed at the bottom of the first and second openings using the inorganic resist film as a mask to form a bottomed small hole in the silicon substrate,
Etching the back side of the bottomed small hole on the back surface of the silicon substrate halfway in the thickness direction to form a discharge liquid chamber having a bottom surface larger than the bottom surface of the bottomed small hole, and a lower end of the bottomed small hole To the bottom of the discharge liquid chamber to form a nozzle hole,
A discharge head manufacturing method for manufacturing a discharge head in which a base oxide film is formed in the nozzle hole and the discharge liquid chamber by thermal oxidation, and then the inorganic resist film is removed and the diamond thin film is disposed on the surface. When forming the first opening, a patterned first organic resist film is formed on the surface of the inorganic resist film, and a portion exposed to the bottom surface of the first resist opening of the first organic resist film Removing the inorganic resist film to form the first opening in the inorganic resist film,
When forming the second opening, after removing the first organic resist film, the portion of the diamond thin film exposed on the bottom surface of the first opening is removed to form the second thin film on the diamond thin film. The ejection head manufacturing method according to claim 1, wherein the opening is formed. After removing the first organic resist film,
A second organic resist film having a second resist opening disposed on the first opening is disposed on the surface of the inorganic resist film, and the second resist opening, the first and second openings, In a state where
3. The method of manufacturing an ejection head according to claim 2, wherein a portion of the silicon substrate exposed at a bottom surface of the first opening is removed by etching leaving a bottom portion in a depth direction to form the bottomed small hole.

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