JP2003237074A - Liquid droplet ejecting head, production method therefor, and ink-jet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejecting head capable of printing with high image quality and high liquid droplet ejecting efficiency at a low cost, a method for producing the liquid ejecting head, and an ink-jet recording apparatus capable of recording with high image quality. <P>SOLUTION: In a liquid ejecting head for ejecting liquid droplets from a nozzle hole by deforming a diaphragm, a plurality of electrodes 14 comprising conductive structures electrically insulated with each other are provided in the diaphragm 10, and a second substrate (protection member) 2 for protecting the electrodes 14 is provided such that the part of the second substrate (protection member) 2 corresponding to the electrodes 14 is opened. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet discharge head, a method of manufacturing the same, and an ink jet recording apparatus.

[0002]

2. Description of the Related Art An ink jet head, which is a liquid drop ejection head used in an ink jet recording apparatus used as an image recording apparatus such as a printer, a facsimile, a copying machine or an image forming apparatus, has a single or a plurality of nozzle holes for ejecting ink droplets. And a discharge chamber (also referred to as an ink chamber, a liquid chamber, a pressurized liquid chamber, a pressure chamber, an ink flow path, etc.) communicating with the nozzle hole, and a pressure generation for generating a pressure for pressurizing the ink in the discharge chamber. And ejecting ink droplets from the nozzle holes by pressurizing the ink in the ejection chamber with the pressure generated by the pressure generating means.

As the droplet discharge head, for example, a droplet discharge head for discharging a liquid resist as droplets, DN
There is also a droplet discharge head that discharges the sample A as droplets, but in the following, an inkjet head will be mainly described. In addition, a microactuator, such as a micropump, that constitutes the actuator portion of the droplet discharge head,
It can also be applied to optical devices such as micro light modulation devices, micro switches (micro relays), actuators (optical switches) of multi-optical lenses, micro flow meters, pressure sensors, and the like.

By the way, as a droplet discharge head, an electromechanical conversion element such as a piezoelectric element is used as a pressure generating means to deform and displace a vibrating plate forming the wall surface of the discharge chamber to discharge ink droplets. Type, bubble type (thermal type) in which bubbles are generated by film boiling of ink and ink droplets are discharged by using an electrothermal conversion element such as a heating resistor arranged in the discharge, wall surface of discharge chamber There is an electrostatic type in which an ink droplet is ejected by deforming a vibration plate that forms an electrostatic force.

In recent years, a lead-free bubble type and an electrostatic type have been attracting attention due to environmental problems. In addition to lead-free, a plurality of electrostatic types have been proposed which have little influence on the environment from the viewpoint of low power consumption. ing.

In this electrostatic head, a vibrating plate is pushed to the ink chamber side to reduce the internal volume of the ink chamber, thereby driving the ink droplets by a pushing method.
It is a knock-out method that ejects ink droplets by deforming the vibration plate with the force in the outer direction of the ink chamber and returning the displacement of the vibration plate to the original inner volume from the state where the inner volume of the ink chamber is expanded. Some are driven.

As a push type electrostatic head, for example, as described in Japanese Patent Application Laid-Open No. 2-266943, ink is filled between a pair of electrodes, and one or both electrodes are filled. There is a type in which the ink acts as a vibrating plate, and when a voltage is applied between the electrodes, an electrostatic attractive force acts between the electrodes, and the electrodes (vibrating plate) are deformed, whereby the ink is pushed out and ejected. In addition, JP-A-200
As described in Japanese Patent Application Laid-Open No. 0-15805, a protrusion is provided on the surface of a diaphragm made of a silicon substrate, electrodes are formed on the protrusion, and a voltage is applied to the electrodes to act between the protrusions. There is also one that deforms the diaphragm by electrostatic force to eject ink.

As the pulling-out method, for example, Japanese Patent Laid-Open No. 6-7
As described in Japanese Patent No. 1882, a pair of electrodes is provided via an air gap, one electrode functions as a diaphragm, and ink is filled on the opposite side of the diaphragm to the opposing electrode. An ink chamber is formed, and by applying a voltage between the electrodes (between the vibrating plate and the electrode), an electrostatic attractive force acts between the electrodes, the electrodes (vibrating plate) are deformed, and when the voltage is removed, the vibrating plate becomes elastic. Some return to the original state and use the force to eject ink. In addition, JP-A-200
As described in JP-A-1-47624, a vibrating plate is provided on one side of electrode pairs formed in a comb shape and nested with each other, and electrostatic force attractive force is generated between the comb teeth by applying a voltage to the electrode pair. Is generated, the diaphragm is deformed by the displacement of the electrode, and the ink is ejected by the elastic force of the diaphragm when the voltage is cut off.

[0009]

However, in the droplet discharge head described in Japanese Patent Laid-Open No. 2-266943, since the ink is filled between the electrodes, the distance between the electrodes inevitably becomes large. Since the electrostatic force acting between the electrodes is inversely proportional to the square of the distance between the electrodes, there is a problem that the required voltage becomes very large as the distance between the electrodes increases. In this case, the voltage can be lowered to some extent depending on the dielectric constant of the ink, but it is not so effective because the distance between the electrodes has a great influence. In addition, the degree of freedom of the ink decreases because it is necessary to increase the dielectric constant of the ink or an electric field is applied to the ink. Therefore, the ink color, p
There is a problem that it is difficult to achieve high image quality because the physical properties of the ink such as H and viscosity are limited.

Further, in the droplet discharge head described in Japanese Patent Laid-Open No. 6-71882, since ink is not filled between the electrodes, there is less restriction on the ink and it is advantageous for high image quality. However, in order to reduce the voltage, the air gap between the electrodes must be made extremely small, and it is very difficult to form such a minute gap with high accuracy and with little variation, and the yield does not increase. There is such a problem. In addition, since it is a so-called pull-out method in which ink is ejected by the elastic force of the diaphragm, the diaphragm needs to have a rigidity sufficient to eject ink, and a voltage for attracting such a diaphragm with electrostatic force is applied. There is a problem that it becomes high.

Further, in the droplet discharge head described in the above-mentioned Japanese Patent Laid-Open No. 2001-47624, since the comb-teeth-shaped electrode is used, the displacement amount can be increased, but the generated force is very small, If an attempt is made to obtain the force required to eject ink, the voltage will become extremely high. Moreover, since the structure is complicated, it is difficult to manufacture, and the cost increases.

Further, in the droplet discharge head described in the above-mentioned Japanese Patent Laid-Open No. 2000-15805, a vibrating plate formed of a conductive silicon substrate is provided with a protrusion, and the protrusion is provided with a conductive member. Since the electrodes are formed, there is a problem in that the electrodes cannot be deformed because the electrostatic potential is not generated between the electrodes via the silicon diaphragm and the electrostatic potential is not generated.

In addition, it is necessary to form a protrusion on the diaphragm and attach an electrode to this protrusion, and it is difficult to attach an electrode to the surface of such a three-dimensional fine structure, and the electrode is not formed well. There is a problem that a part is formed or variation occurs, stable manufacturing cannot be performed, and yield is low. Furthermore, in order to reduce the voltage, it is necessary to narrow the gap between the protrusions, but it is difficult to form electrodes in such a narrow gap, and if electrodes are formed between the narrow protrusions, short-circuiting occurs. There is a defect that it will happen.

Further, it is not possible to form electrodes on the protrusions by a general method because it is difficult to perform resist coating and exposure in the photolithography process in a three-dimensional structure. Therefore, a special device is used. However, there is a problem that the cost increases due to the increase in manufacturing process and the lengthening of the manufacturing process.

The present invention has been made in view of the above problems, and is for producing a droplet discharge head that is low in cost, has high droplet discharge efficiency, and is capable of high-quality printing, and a droplet discharge head for manufacturing the same. An object of the present invention is to provide a method for manufacturing a droplet discharge head, and an inkjet recording device capable of high-quality recording.

[0016]

In order to solve the above-mentioned problems, a droplet discharge head according to the present invention comprises a vibrating plate having a plurality of electrodes made of a conductive structure electrically isolated from each other. Provided with a protective member to protect this electrode,
The portion of the protective member corresponding to the electrode is opened.

Here, the electrodes preferably have a multilayer structure. Further, it is preferable that the portion of the same plane as the electrode has the same layer structure as the electrode.

In the method of manufacturing a droplet discharge head according to the present invention, a vibrating plate constituting at least one wall surface of a discharge chamber communicating with a nozzle hole for ejecting a liquid drop, and the vibrating plate are electrically isolated from each other. A plurality of electrodes made of a conductive structure that has been protected, and a protective member that protects the electrodes,
A method of manufacturing a droplet discharge head in which an electrostatic force is generated between electrodes to deform a vibration plate, in which electrodes are formed on a protective member.

Here, after forming the electrodes, it is preferable to provide at least a part of the vibration plate on the electrodes.

The ink jet recording apparatus according to the present invention is
The inkjet head for ejecting ink droplets is manufactured by the manufacturing method according to the present invention.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an inkjet head according to the droplet discharge head of the present invention, and is shown in a partial sectional view. 2 is a sectional explanatory view of the same head in the longitudinal direction of the diaphragm, FIG. 3 is a sectional explanatory view of the same head in a lateral direction of the diaphragm, FIG. 4 is an enlarged explanatory view of electrodes of the same head, and FIG. 5 is an electrode of FIG. It is a plane explanatory view of a pattern.

This ink jet head is of a side shooter type in which ink droplets are ejected from nozzle holes provided on the surface of the substrate, and three first, second and third ink jet heads having a structure described in detail below are provided. It has a laminated structure in which the substrates 1, 2 and 3 are stacked and joined, and a plurality of nozzle holes 4 for ejecting ink droplets, an ejection chamber 6 communicating with each nozzle hole 4, and a fluid resistance portion 7 in each ejection chamber 6. A common liquid chamber (common ink chamber) 8 for supplying ink via the same is formed.

The intermediate first substrate 1 is made of a silicon substrate and has a concave portion (penetration portion) for forming the ejection chambers 6 and a common liquid chamber 8 for supplying ink to each ejection chamber 6. Has a concave portion (penetrating portion) for.

The second substrate 2 bonded to the lower surface of the first substrate 1 is a support / protection substrate (protection member) and is provided with a vibrating plate 10 forming a part of the wall surface of the discharge chamber 6. This diaphragm 10 is made of a silicon nitride film, a silicon nitride film, a laminated film of these films, or a resin film such as a polyethylene film, a polypropylene film, an ionomer film, a polycarbonate film, a polyimide film, a polyamide film, or a polyvinyl chloride film. It consists of an insulating film.

On the lower surface of the vibrating plate 10, a plurality of electrodes 14 made of a conductive structure electrically isolated from each other are provided at predetermined intervals. In this case, since the diaphragm 10 itself is an insulating film, the electrodes 14 are not electrically connected via the diaphragm 10. In addition, two adjacent electrodes of each of the electrodes 14 (which are relatively referred to as electrodes 14a and 14b) are also electrically separated from each other through a gap. The diaphragm 10 and the plurality of electrodes 14 constitute an electrostatic actuator.

Here, as shown in FIGS. 3 and 4, in each electrode 14, the width of the fixed end portion 14A fixed to the diaphragm 10 side (here, the width in the lateral direction of the diaphragm) is the intermediate portion 14B. The width of the intermediate portion 14B is smaller than that of the free end portion 14C. That is, the electrode 1
The distance between the electrodes 4 and 14 is such that the fixed end side of the electrode is wider than the free end side thereof, that is, as shown in FIG. The distance d3 on the free end side is formed to be d1>d2> d3. In the figure, L is the height of the electrode 14.

FIG. 5 shows an example of the electrode arrangement pattern for one diaphragm when viewed from the electrode 14 side of the first substrate 1. As shown in the figure, a driving voltage (a voltage having a different potential) that causes a potential difference from each other is applied from a driving circuit (here, shown as a transmission circuit) 15 to the electrodes 14a and 14b that are electrically separated from each other. It is supposed to be done.

Second substrate (support / protection substrate) 2 and diaphragm 10
A partition 12 having a three-layer structure made of the same material as that of the electrode 14 is formed on the same plane as the electrode 14. The layer structure of the partition wall portion 12 is revealed by the manufacturing process according to the present invention in which the electrode 14 is formed on the support / protection substrate 2 as described later.

An opening 16 is formed in a portion of the second substrate 2 corresponding to the electrode 14. The opening 16 is also revealed by the manufacturing process according to the present invention in which the electrode 14 is formed on the support / protection substrate 2 as described later.

The second substrate 2 is for protecting the electrode 14 from contact with the outside and for supporting and reinforcing the strength of the first substrate 1, the diaphragm 5, the electrode 14 and the like. This second
As the substrate 2, a substrate made of glass, metal, silicon, resin or the like can be used, but a silicon substrate is preferably used in the manufacturing process. Further, the opening 16 of the second substrate 2 does not necessarily have to be formed for each diaphragm 10,
It may be formed in a recess surrounding the diaphragm array or in the entire area other than the edge of the chip. Furthermore, a lid member that covers the opening 16 of the second substrate 2 may be provided.

The third substrate bonded to the upper surface of the first substrate 1
For the substrate 3, for example, a nickel substrate having a thickness of 50 μm is used, and a fluid resistance portion for communicating the nozzle hole 4, the common liquid chamber 8 and the discharge chamber 6 with the surface portion of the third substrate 3 so as to communicate with the discharge chamber 6, respectively. 7 is provided, and an ink supply port 9 is provided so as to communicate with the common liquid chamber 8.

Although the ink jet head has a laminated structure in which the three substrates 1, 2 and 3 described above are stacked and bonded to each other, the substrate 1 and the substrate 3 are manufactured as the same substrate, and the two substrates are manufactured. It is also possible to form a laminated structure in which the above substrates are stacked and joined.

The operation of the ink jet head thus constructed will be described. For example, in the configuration of FIG.
When a pulse potential of 0V to 40V is applied to 4a by the oscillating circuit 15, the surface of the electrode 14a is positively charged, and as shown in FIG. Electric power is generated, electrostatic attraction works, the free ends of the electrodes 14 (the fixed end on the diaphragm 10 side) attract each other, and the electrodes 14 are displaced.
The displacement of the free end of the electrode causes the diaphragm 10, which is the fixed end of the electrode 14, to bend upward. As a result, the pressure in the ejection chamber 6 rapidly increases, and the ink droplets 22 are ejected from the nozzle holes 4 toward the recording paper 23 as shown in FIG.

When the potential of the electrode 14a returns to 0V, the potential difference between the electrode 14b and the electrode 14b disappears, and the vibration plate 10
Restores the original state. When the vibration plate 10 is restored, ink is replenished from the common liquid chamber 8 into the ejection chamber 6 through the fluid resistance portion 7. That is, in this embodiment, the ink droplets are ejected by the pushing method.

As described above, in this ink jet head, the electrodes 14 which are electrically separated and independent from each other are provided on one surface of the vibration plate 10, and the electrodes 1 opposed to the electrodes 14 are provided.
By applying a voltage that causes a potential difference between the electrode 4a and the electrode 14b, an electrostatic attractive force is generated between the adjacent electrodes 14a and 14b, and a slight displacement of the electrode 14 can obtain a large displacement of the diaphragm 10. Therefore, the droplet ejection efficiency is improved, and high image quality recording is possible.

Further, in this head, the diaphragm 10
Since the structure itself provided in 1 functions as the electrode 14, there is no need for the difficult step of forming an electrode on the silicon structure by a method such as film formation as in the past, and cost reduction can be achieved. Further, it is possible to reduce defects such as a short circuit caused by forming electrodes at very narrow intervals between the structures. Furthermore, there is no need for a step of separating the electrodes into comb teeth after forming the electrodes on the structure,
Low cost and easy mass production.

Further, since the diaphragm 10 and the electrodes 14 are electrically separated, even if a voltage is applied to the electrodes as in the conventional case, all the electrodes have the same potential through the diaphragm and malfunction occurs. The voltage applied to the electrode 14 does not leak to the diaphragm 10 side, and the voltage can be efficiently applied to the electrode 14.

Here, the force F acting between the electrodes is defined by the following (1)
As shown in the equation, it increases in inverse proportion to the square of the inter-electrode distance d, and the bending moment acting on the diaphragm increases in proportion to the height L of the structure (electrode). Therefore, in order to displace the diaphragm efficiently, a position (height L
Is large), it is important to form a narrow gap between the electrodes 4a and 4b.

[0039]

[Equation 1]

In the equation (1), F: force acting between the electrodes, ε: permittivity, S: area of facing surfaces of the electrodes, d:
Distance between electrodes, V: applied voltage.

Further, since the electrode (structure) itself does not bend, the deformable region of the diaphragm is formed by forming a wide electrode interval at the base portion (fixed end fixed to the diaphragm) of the electrode (structure). Can be expanded, and the diaphragm can be efficiently displaced.

Therefore, by making the distance between electrodes (electrode spacing) wide on the diaphragm side (fixed end side of the electrode) and narrow on the side away from the diaphragm (free end side of the electrode), The diaphragm can be efficiently and largely displaced.

In order to displace the diaphragm more efficiently and largely, it is preferable to increase the height L of the structure (electrode) as described above. In this case, if it becomes necessary to deposit a very thick film to form the structure, the process cost will increase, and it will be difficult to form a narrow electrode interval by etching or the like. Further, if the deposited film is thin, the mechanical strength of the structure may be weakened, the diaphragm cannot be efficiently displaced, and the yield may be reduced due to damage of the structure itself.

Therefore, in the head of this embodiment, the electrode interval is made to differ in a plurality of steps, particularly three or more steps, and the electrode interval is wide on the fixed end side and narrow on the free end side. While maintaining the mechanical strength of the electrode, the electrode can be formed without making the thickness of the film deposited very thick, and the height L of the structure is increased while suppressing the increase of the process cost, and the vibration is increased. The plate can be displaced more efficiently and largely.

Next, a first embodiment of a method of manufacturing an ink jet head which is a liquid droplet ejection head according to the present invention will be described with reference to FIGS. 7 and 8. It should be noted that the drawing shows an example in which an electrode is provided on one surface of the diaphragm, and the illustration of the surface of the substrate on which the electrode is not provided is omitted.

First, as shown in FIG. 7A, the silicon substrate 2 serving as the second substrate having a plane orientation (110) and a thickness of 400 μm is thermally oxidized to form a silicon oxide film 21a on the silicon substrate 2. To a thickness of 1 μm. The silicon oxide film 21a can be formed by a method such as CVD, or a silicon nitride film can be used instead of the silicon oxide film.

Then, a polysilicon film 22a having a thickness of 2.5 μm is deposited as a film for forming the electrode 14 on the silicon oxide film 21a by a CVD method, and a lithography technique and a dry etching technique using high-density plasma are used. Thus, the polysilicon film 22a is patterned to form a groove 23 having a width of 0.4 μm and serving as an electrode interval. Here, the silicon oxide film 21a functions as an etching stopper when the polysilicon film 22 is etched.

The film forming the electrodes is not limited to polysilicon but may be a metal or a semiconductor, but it is preferable to use polysilicon or silicon which can form the electrode interval by dry etching with relatively high precision.

When non-doped polysilicon is driven at a high frequency or multi-channels, the electric resistance of the electrode may become a problem. In this case, impurity atoms having n-type or p-type conductivity, For example, it is preferable to reduce the electric resistance value by introducing phosphorus or arsenic for n-type and boron or antimony for p-type.

Further, a silicon oxide film 21b is formed to a thickness of 3 μm by the CVD method (at this time, the groove 23 is made into the silicon oxide film 2).
It is embedded in 1b. After that, the substrate surface is flattened by CMP.

Then, as shown in FIG. 3B, a silicon oxide film 21c is deposited to a thickness of 3 μm, and the silicon oxide film 21c is patterned by a known lithography and dry etching technique, so that a width of 4 μm is obtained. The opening 24 is formed. Then, as shown in FIG.
Polysilicon film 22b is formed on the surface by CVD method at 2.5μ
Deposit to a thickness of m. Since the thickness of the polysilicon film required to obtain the flatness of the substrate in which the opening 24 is embedded is 2 μm or more, the requirement for burying is satisfied here, and the substrate is almost flattened.

Further, as shown in FIG. 3D, the polysilicon film 22b is patterned by lithography and dry etching techniques, and further, a silicon oxide film 21d is deposited to a thickness of 3 μm and the surface of the substrate is flattened by CMP.

After that, although not shown, the silicon oxide film and the polysilicon film formed on the back surface of the silicon substrate 2 are removed by an etching solution or the like. It may be removed by polishing (preferably including a lapping or polishing step using a grinder).

Next, as shown in FIG. 8A, a silicon nitride film 25 to be the diaphragm 10 is formed by LP-CVD to a thickness of 0.5 μm. Although not shown, the silicon nitride film 25 is also formed on the back surface of the silicon substrate 2 and can be used as an etching mask for an aqueous potassium hydroxide solution or the like.

Thereafter, as shown in FIG. 6B, the silicon substrate 2 is etched using a potassium hydroxide aqueous solution or the like by using the silicon nitride film 25 on the back surface of the patterned silicon substrate 2 as a mask, and the opening 26 is formed. To form. At this time, the silicon oxide film 21a functions as an etching stopper. As a result, the electrode 1 is formed between the silicon substrate 2 and the diaphragm 10 (silicon nitride film 25) on the same plane as the electrode 14 via the silicon oxide film 21a.
The partition wall 12 having the same three-layer structure as that of 4 appears.

Further, as shown in FIG. 7C, the silicon oxide films 21a, 21b, 21c and 21d are removed by etching with a buffered hydrofluoric acid aqueous solution (BHF) or the like, so that the distance between the electrodes is three steps as described above. (D1, d
2 and d3), the electrode 14 is formed of a structure that is wide (d1) on the diaphragm side and narrow (d3) on the side away from the diaphragm. The electrode 14 can displace the diaphragm 10 efficiently, and the yield can be improved.

Although the structure in which the inter-electrode distance is different in three steps is used here, the present invention is not limited to this and the inter-electrode distance may be three or more steps or less. The structure does not have to be different.

The vibrating plate 10 made of the silicon nitride film 25 functions as an etching stopper and is also an insulating film, so that it is electrically separated from the electrode 14. However, since the silicon nitride film is under tensile stress, the diaphragm will not buckle, but the diaphragm may not be deformed by the tensile stress. In such a case, the stress can be relaxed by doping the silicon nitride film with impurities such as boron, phosphorus and hydrogen.

Thereafter, although not shown, a partition wall of the discharge chamber 6,
The droplet discharge head is completed by joining the substrate 1 having the partition walls of the common liquid chamber 8 for supplying ink to the respective discharge chambers 6 and the substrate 3 having the nozzle holes and the like.

Since the electrodes are formed on the support / protection substrate side as described above, the step of joining the support / protection substrates through the surface on which the electrode having the narrow gap is formed is not required, and the manufacturing yield is improved. Therefore, it is possible to manufacture a droplet discharge head having high reliability. Further, as described above, when manufacturing a structure in which the distance between the electrodes is wide on the diaphragm side, sacrificial layer etching is used. However, in the present invention, the number of deposited film process steps can be reduced, or the film to be etched is an etching solution. It is possible to facilitate the etching of the sacrifice layer, and this effect also improves the manufacturing yield.

Next, a second embodiment of a method of manufacturing an ink jet head which is a droplet discharge head according to the present invention will be described with reference to FIGS. 9 and 10. First, FIG.
As shown in (a), the plane orientation (110) has a thickness of 400
LP-CV with the silicon substrate 2 serving as the second substrate of μm on top
A silicon nitride film 31 is formed by D to a thickness of 0.3 μm. Then, the silicon oxide film 2 is formed on the silicon nitride film 31.
After forming 1a to a thickness of 2.5 μm, patterning is performed, and then a polysilicon film 22a is deposited to a thickness of 3 μm by a CVD method as a film forming an electrode, and the substrate surface is flattened by CMP.

Then, as shown in FIG. 6B, after a part of the silicon oxide film 21a is removed by etching by the lithography and dry etching techniques, a silicon oxide film 21b is further deposited to a thickness of 0.3 μm and the whole surface is deposited. By dry etching, the silicon oxide film 21b is left on the sidewall of the polysilicon film 22a forming the electrode.

Here, the silicon oxide film 21b is a sacrificial layer, and the electrode interval is formed by etching the sacrificial layer (silicon oxide film 21b) in a later step.
That is, since the electrode spacing is defined by the thickness of the sacrificial layer, it is possible to form a high-aspect groove, which is difficult to etch, with high accuracy.

Thereafter, as shown in FIG. 6C, a polysilicon film 22b is deposited to a thickness of 3.5 μm by the CVD method. The thickness of the polysilicon film required to obtain the flatness of the substrate with the gaps embedded therein is 3 μm or more. That is,
Here, the embedding requirements are satisfied, and the substrate surface is also substantially flattened. Further, after that, the surface roughness is reduced by CMP or the like, so that the subsequent bonding reliability can be improved. Although the polysilicon film is deposited so as to be substantially flattened here, it may be flattened by a combination of CMP and the like without being flattened by the deposition.

Next, as shown in FIG. 6D, the polysilicon film 22b is patterned by lithography and dry etching techniques.

Then, as shown in FIG. 10A, the silicon oxide film 21a is formed into a buffered hydrofluoric acid aqueous solution (BHF).
The electrode 14 is formed by etching and removing it. In this way, the silicon substrate 2 which is the support / protection substrate
By forming the electrode 14 on the upper surface, the electrode 14 is easily exposed to the etching solution, and the silicon oxide film 21a can be easily removed by etching. Further, since it is not necessary to deposit the silicon oxide film up to the height which becomes the electrode 14, the process cost can be reduced.

Since the silicon nitride film 31 and the polysilicon films 22a and 22b have a very low etching rate with respect to BHF and are hardly etched, the electrode 14 can be formed. Note that the material of the film used in this embodiment is not limited to those listed above, and when manufacturing a structure like this embodiment, a film corresponding to a silicon nitride film, a polysilicon film, or the like is not used. A film that is difficult to be etched by the etching liquid for the sacrificial layer may be used.

Next, as shown in FIG. 3B, the silicon substrate 1 which is the first substrate on which the high concentration boron layer 32 and the low melting point glass film 33 are formed is bonded to the silicon substrate 2. If the two substrates have different thicknesses, the two substrates can be simultaneously etched in a later step by etching the substrates by reducing the thickness difference by polishing or the like.

Although not shown, a silicon nitride film is formed on both surfaces of the bonded substrate by LP-CVD, and the patterned silicon nitride film is used as a mask by a photolithography technique and a dry etching technique to form a mask.
80% to 90% by weight of potassium hydroxide aqueous solution
Anisotropic etching is performed on the substrate 1 and the substrate 2 at ℃.

At this time, in the silicon substrate 1, when the anisotropic anisotropic etching is performed, the etching rate becomes extremely small when the high-concentration boron layer 32 is exposed (so-called etch stop). And the discharge chamber 6 is formed at the same time. In addition,
Other than high-concentration boron stop, N-type on P-type silicon substrate
Method of forming a P-type layer or a P-type layer of an N-type silicon substrate to stop electrochemical etching, SOI (Silicon
It is also possible to use a method of stopping the etching in the insulator portion (silicon oxide film or silicon nitride film) of the on insulator structure.

In the silicon substrate 2, the silicon nitride film 31 functions as an etching stopper when the opening 26 is formed in the alkali anisotropic etching.

After that, the silicon nitride film and the silicon nitride film 31 of the mask are removed by etching using an etching solution such as phosphoric acid.

Next, a third embodiment of a method of manufacturing an ink jet head which is a liquid droplet ejection head according to the present invention will be described with reference to FIG. First, as shown in FIG. 3A, the silicon substrate 2 serving as the second substrate having a plane orientation (110) and a thickness of 400 μm is thermally oxidized to form a silicon oxide film 21 a having a thickness of 1 μm on the silicon substrate 2. Form to thickness. The silicon oxide film 21a can be formed by a method such as CVD, or a silicon nitride film can be used instead of the silicon oxide film.

Then, a polysilicon film 22a having a thickness of 2.5 μm is deposited on the silicon oxide film 21a as a film for forming the electrode 14 by the CVD method, and a lithography technique and a dry etching technique using high-density plasma are used. Thus, the polysilicon film 22a is patterned to form a groove 23 having a width of 0.4 μm and serving as an electrode interval. Here, the silicon oxide film 21a functions as an etching stopper when the polysilicon film 22a is etched.

Further, the silicon oxide film 21b is formed to a thickness of 3 μm by the CVD method (at this time, the groove 23 is formed in the silicon oxide film 2b).
It is embedded in 1b. After that, the substrate surface is flattened by CMP.

Next, as shown in FIG. 9B, a silicon oxide film 21c is deposited to a thickness of 3 μm, and the silicon oxide film 21c is patterned by the known lithography and dry etching techniques. As a result, the opening 24 having a width of 2 μm is formed.

Then, as shown in FIG. 7C, a silicon nitride film 41 for forming the vibration plate 10 is formed on the surface of 1.
Deposit to a thickness of 5 μm. The thickness of the polysilicon film required to obtain the flatness of the substrate with the gaps embedded therein is 1 μm or more. So here we have the embedding requirements,
The substrate is also almost flattened. At the same time, the diaphragm 10 made of the silicon nitride film 41 is formed. Here, the surface of the substrate may be dry-etched to adjust the thickness of the diaphragm 10 made of the silicon nitride film 31 to be thin. In this way, the structure that is the electrode 14 is formed and the diaphragm 1
By forming 0s at the same time, the manufacturing cost can be reduced.

After that, as shown in FIG. 7D, the opening 26 is formed by etching the silicon substrate 2 with a potassium hydroxide aqueous solution or the like using the patterned silicon nitride film on the back surface as a mask. Here, the silicon oxide film 21a functions as an etching stopper. In forming the opening, a lithography technique and a dry etching technique using high density plasma may be used.

Then, as shown in FIG. 7E, the silicon oxide films 21a, 21b and 21c are removed by etching with a buffered hydrofluoric acid aqueous solution (BHF) or the like, so that the distance between the structures is wide on the diaphragm side and the vibration is reduced. The electrode 14 is formed of a structure that is narrower on the side away from the plate. At this time, the partition 12 having the same layer structure as the electrode 14 is formed on the same plane as the electrode 14.

Next, a fourth embodiment of a method of manufacturing an ink jet head which is a droplet discharge head according to the present invention will be described with reference to FIG. First, as shown in FIG. 3A, the silicon substrate 2 serving as the second substrate having a plane orientation (110) and a thickness of 400 μm is thermally oxidized to form a silicon oxide film 21 a having a thickness of 1 μm on the silicon substrate 2. Form to thickness. The silicon oxide film 21a can be formed by a method such as CVD, or a silicon nitride film can be used instead of the silicon oxide film.

Then, a polysilicon film 22a having a thickness of 2.5 μm is deposited on the silicon oxide film 21a by a CVD method as a film for forming the electrode 14, and a lithography technique and a dry etching technique using high density plasma are used. Thus, the polysilicon film 22a is patterned to form a groove 23 having a width of 0.4 μm and serving as an electrode interval. Here, the silicon oxide film 21a functions as an etching stopper when the polysilicon film 22a is etched.

Further, the silicon oxide film 21b is formed to a thickness of 3 μm by the CVD method (at this time, the groove 23 is formed on the silicon oxide film 2b).
It is embedded in 1b. After that, the substrate surface is flattened by CMP.

Then, as shown in FIG. 9B, a silicon oxide film 21c is deposited to a thickness of 3 μm, and the silicon oxide film 21c is patterned by a known lithography and dry etching technique. As a result, the opening 24 having a width of 2 μm is formed.

Thereafter, as shown in FIG. 7C, a silicon nitride film 41 is deposited to a thickness of 0.3 μm. Since the silicon nitride film 41 cannot fill the groove 24 with this thickness, the silicon nitride film 41 is formed on the side wall surface of the groove 24. Then, the silicon oxide film 21d is
After depositing to a thickness of m, the substrate is planarized by CMP.

The CMP will be described below. CM
Although P will polish the silicon oxide film 21d, as the polishing progresses, the silicon nitride film 41 is exposed on the substrate surface. Since the silicon nitride film has a much slower polishing rate than the silicon oxide film, it serves as a suitable polishing stopper, and the substrate can be planarized easily and accurately.

Then, as shown in FIG. 3D, a liquid of polyimide and an organic solvent is spin-coated on the surface of the substrate and baked to form a polyimide film 4 having a thickness of 3 μm.
Form 2. Thus, the diaphragm 10 having the polyimide film 42 as a constituent member is formed.

Since polyimide exhibits high resistance to dissolution and swelling in ink, it is possible to manufacture a highly reliable droplet discharge head by using a film such as a polyimide film for the vibrating plate.

Further, since polyimide has a heat resistance of about 300 ° C., it is impossible to go through a process step having a higher temperature after forming the polyimide film. A material having high ink resistance even though it does not have heat resistance, such as polyimide, is formed by forming a diaphragm after the step of forming electrodes, which has a high temperature such as polysilicon film deposition as in the present embodiment. Can be used for. This improves the reliability of the head.

Further, it is possible to collectively form the vibration plate, the electrodes, and the support / protection substrate on one substrate, and it is possible to avoid defects due to the intervention of the joining process and to manufacture with a high yield. .

Although the polyimide film is formed by spin coating and baking, it may be formed by spray coating or the like, or film-like polyimide may be formed by adhesion or lamination.

Thereafter, as shown in FIG. 9D, the opening 26 is formed in the silicon substrate 2 even if the back surface is subjected to the lithography technique and the dry etching technique using high-density plasma.
And then the silicon oxide films 21a, 21b and 21c are formed.
Are removed by etching with a buffered hydrofluoric acid aqueous solution (BHF) or the like to form the electrode 14. The polyimide film 40 is protected by a protective film such as a resist.

Although not shown in the drawing, the partition walls of the ejection chambers 6, the silicon substrate 1 having the partition walls of the common liquid chamber 8 for supplying ink to each ejection chamber 6, the third substrate 3 having the nozzle holes, etc. The droplet discharge head is completed by joining the.

Next, an ink cartridge equipped with the droplet discharge head according to the present invention will be described with reference to FIG. This ink cartridge 100 has a nozzle hole 101.
The inkjet head 101 according to any one of the above-described embodiments having the above-described features and the ink tank 102 that supplies ink to the inkjet head 101 are integrated.

As described above, in the case of the head integrated with the ink tank, the cost reduction and reliability of the head immediately leads to the cost reduction and reliability of the entire ink cartridge. Therefore, as described above, the cost reduction and high reliability are achieved. By improving the performance and reducing manufacturing defects, the yield and reliability of the ink cartridge can be improved, and the cost of the head-integrated ink cartridge can be reduced.

Next, an example of an ink jet recording apparatus equipped with an ink jet head (including a head-integrated ink cartridge) which is a droplet discharge head according to the present invention will be described with reference to FIGS. 14 and 15. 14 is a perspective explanatory view of the recording apparatus, and FIG. 15 is a side view of a mechanical portion of the recording apparatus.

This ink jet recording apparatus has a carriage movable inside the recording apparatus main body 111 in the main scanning direction, a recording head including the ink jet head according to the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. Printing mechanism section 11 composed of
A sheet feeding cassette (or a sheet feeding tray) 114 capable of accommodating a large number of sheets 113 from the front side can be detachably attached to the lower portion of the apparatus main body 111 for accommodating 2 or the like. The manual feed tray 115 for manually feeding the paper 113 can be opened and closed, the paper 113 fed from the paper feed cassette 114 or the manual feed tray 115 is taken in, and a desired image is recorded by the printing mechanism unit 112. After that, the output tray 1 mounted on the rear side
The paper is discharged to 16.

The printing mechanism section 112 slides the carriage 123 in the main scanning direction (the direction perpendicular to the paper surface in FIG. 15) by the main guide rod 121 and the sub guide rod 122, which are guide members which are horizontally mounted on the left and right side plates (not shown). The carriage 123 is freely held, and yellow (Y), cyan (C),
A head 124, which is an ink jet head that is a droplet ejection head according to the present invention that ejects ink droplets of each color of magenta (M) and black (Bk), is arranged in a direction in which a plurality of ink ejection ports intersects the main scanning direction. , The ink droplet ejection direction is downward. Also, the carriage 123
Each ink cartridge 125 for supplying each color ink to the head 124 is replaceably mounted. The head-integrated ink cartridge according to the present invention can be mounted.

The ink cartridge 125 has an upper atmosphere port communicating with the atmosphere, a lower supply port for supplying ink to the ink jet head, and a porous body filled with ink in the interior. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of.

Further, although the heads 124 of the respective colors are used here as the recording head, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

Here, the carriage 123 is slidably fitted to the main guide rod 121 on the rear side (downstream side in the sheet transport direction) and slidably fitted to the slave guide rod 122 on the front side (upstream side in the sheet transport direction). It is placed in. Then, in order to move and scan the carriage 123 in the main scanning direction, a timing belt 130 is stretched between the drive pulley 128 and the driven pulley 129 which are rotationally driven by the main scanning motor 127, and the timing belt 130 is mounted on the carriage 123. The carriage 123 is reciprocally driven by the forward and reverse rotations of the main scanning motor 127.

On the other hand, in order to convey the paper 113 set in the paper feed cassette 114 to the lower side of the head 124, the paper feed roller 131 and the friction pad 132 for separately feeding the paper 113 from the paper feed cassette 114, and the paper 11 are provided.
Guide member 133 for guiding the sheet 3 and the fed sheet 11
A conveyance roller 134 that reverses and conveys 3 is provided, a conveyance roller 135 that is pressed against the peripheral surface of the conveyance roller 134, and a leading end roller 136 that defines the feed angle of the paper 113 from the conveyance roller 134. Conveyor roller 1
The sub-scanning motor 137 is rotationally driven through a gear train.

A print receiving member 139, which is a paper guide member for guiding the paper 113 sent out from the conveying roller 134 below the recording head 124, is provided in correspondence with the range of movement of the carriage 123 in the main scanning direction. There is. A transport roller 141 and a spur 142 that are driven to rotate in order to send out the paper 113 in the paper discharge direction are provided on the downstream side of the print receiving member 139 in the paper transport direction, and further, the paper 113 is sent to the paper discharge tray 116. Roller 143 and spur 1
44, and guide members 145 and 146 that form the paper discharge path
And are arranged.

At the time of recording, by driving the recording head 124 according to the image signal while moving the carriage 123, ink is ejected onto the stopped paper 113 to record one line, and the paper 113 is moved by a predetermined amount. After transportation, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 113 reaches the recording area, the recording operation is ended and the paper 113 is ejected. In this case, the head 12
In the ink jet head according to the present invention, which composes No. 4, the controllability of ink droplet ejection is improved and the characteristic variation is suppressed, so that an image with high image quality can be stably recorded.

A recovery device 147 for recovering the ejection failure of the head 124 is arranged at a position outside the recording area on the right end side of the carriage 123 in the moving direction. The recovery device 147 has a cap means, a suction means, and a cleaning means. The carriage 123 is moved to the recovery device 147 side while the printing is on standby, the head 124 is capped by the capping means, and the ejection port portion is kept wet to prevent ejection failure due to ink drying.
Also, by ejecting ink that is not related to recording during recording, etc., the ink viscosity of all ejection ports is made constant,
Maintains stable discharge performance.

When ejection failure occurs, the ejection port (nozzle) of the head 124 is sealed with a capping means.
Bubbles and the like are sucked out together with the ink from the discharge port by the suction means through the tube, and the ink and dust adhering to the surface of the discharge port are removed by the cleaning means to recover the discharge failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed in the lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

As described above, in this ink jet recording apparatus, since the ink jet head or the ink cartridge embodying the present invention is mounted, there is no ink droplet ejection failure due to defective driving of the diaphragm, and stable ink droplet ejection characteristics are obtained. As a result, the image quality is improved. Further, since a head that can be driven at a low voltage is mounted, the power consumption of the entire inkjet recording device can be reduced.

In the above embodiment, the example in which the droplet discharge head is applied to the ink jet head has been described. However, as the droplet discharge heads other than the ink jet head, for example, the droplet discharge for discharging the liquid resist as droplets. The present invention can also be applied to other droplet discharge heads such as a head and a droplet discharge head that discharges a DNA sample as droplets.

The electrostatic actuator portion of the droplet discharge head includes a micro pump, an optical device (light modulation device), a micro switch (micro relay), a multi-optical lens actuator (light switch), a micro flow meter, and a pressure. It can also be applied to microdevices such as sensors.

[0109]

As described above, according to the droplet discharge head of the present invention, the vibrating plate is provided with a plurality of electrodes made of a conductive structure that is electrically isolated from each other. Since the protective member for protecting the protective member is provided and the portion corresponding to the electrode of the protective member is opened, it becomes possible to form the electrode on the protective member, the cost is low, and the droplet ejection efficiency is low. It is possible to obtain a head that is high and capable of high-quality recording.

Here, since the electrode has a multi-layer structure, the displacement restraint region of the diaphragm by the electrode can be reduced and the displacement efficiency is improved. Further, since the portion on the same plane as the electrode has the same layer structure as the electrode, the electrode can be easily formed on the protective member.

According to the method of manufacturing the droplet discharge head of the present invention, the droplet discharge heads are electrically insulated and separated from each other forming at least one wall surface of the discharge chamber communicating with the nozzle hole for discharging the droplets. When a plurality of electrodes made of a structure is formed, the electrodes are formed on the protective member that protects the electrodes, so that the yield is improved and a highly reliable head can be obtained.

By forming at least a part of the vibrating plate on the electrode after forming the electrode, the vibrating plate can be formed even with a material that is easily affected by thermal history in the process, and the liquid resistant The diaphragm can be made of a certain material, and the reliability is improved.

According to the ink jet recording apparatus of the present invention, since the ink jet head for ejecting ink droplets is manufactured by the manufacturing method of the present invention, high quality recording can be performed at low cost with high reliability. A good recording device available.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating an inkjet head according to a droplet discharge head of the present invention.

FIG. 2 is a cross-sectional explanatory view of the same head in the diaphragm longitudinal direction.

FIG. 3 is an enlarged cross-sectional explanatory view of a main part of the head in a lateral direction of a diaphragm.

FIG. 4 is an enlarged explanatory view of an electrode portion of the same head.

FIG. 5 is an explanatory plan view illustrating an electrode arrangement pattern of the head.

FIG. 6 is an enlarged cross-sectional explanatory view of a main part for explaining the operation of the head.

FIG. 7 is an explanatory view illustrating a first embodiment of a head manufacturing method according to the present invention.

FIG. 8 is an explanatory diagram illustrating a step following FIG.

FIG. 9 is an explanatory view illustrating a first embodiment of a head manufacturing method according to the present invention.

FIG. 10 is an explanatory diagram explaining a step following FIG. 9;

FIG. 11 is an explanatory diagram illustrating a third embodiment of a head manufacturing method according to the present invention.

FIG. 12 is an explanatory diagram illustrating a third embodiment of a head manufacturing method according to the present invention.

FIG. 13 is a perspective explanatory diagram for explaining a head-integrated ink cartridge including a droplet discharge head according to the present invention.

FIG. 14 is a perspective explanatory view illustrating an example of an inkjet recording apparatus according to the present invention.

FIG. 15 is an explanatory diagram of a mechanical section of the recording apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st substrate, 2 ... 2nd substrate (protective member), 3 ... Nozzle plate, 4 ... Nozzle hole, 6 ... Discharge chamber, 7 ... Fluid resistance part, 8 ...
Common liquid chamber, 10 ... diaphragm, 14 ... electrode,

Continued front page    F-term (reference) 2C057 AF93 AG12 AG54 AG55 AG93                       AP02 AP32 AP34 AP53 AP56                       AQ02 AQ06 BA03 BA15

Claims (6)

[Claims] 1. A nozzle hole for discharging a droplet, a discharge chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the discharge chamber, the vibration plate being deformed. In a droplet discharge head that discharges droplets from the nozzle holes, a plurality of electrodes made of a conductive structure electrically isolated from each other are provided on the vibration plate, and a protection member for protecting the electrodes is provided. A droplet discharge head, wherein a portion of the protective member corresponding to the electrode is opened. 2. The droplet discharge head according to claim 1, wherein the electrode has a multilayer structure. 3. The droplet discharge head according to claim 2, wherein a portion of the same plane as the electrode has the same layer structure as the electrode. 4. A nozzle hole for discharging droplets, a discharge chamber communicating with each of the nozzle holes, a vibration plate forming at least one wall of the discharge chamber, and an electric insulation between the vibration plate and each other. Manufacture of a droplet discharge head that has a plurality of electrodes composed of separated conductive structures and a protection member that protects the electrodes, and that deforms the diaphragm by generating an electrostatic force between the electrodes A method of manufacturing a droplet discharge head, comprising forming the electrode on the protective member. 5. The method of manufacturing a droplet discharge head according to claim 4, wherein after forming the electrode, at least a part of the vibration plate is provided on the electrode. Production method. 6. An ink jet recording apparatus provided with an ink jet head for ejecting ink droplets, wherein the ink jet head is manufactured by the method for manufacturing a liquid drop ejection head according to claim 4. An inkjet recording device characterized by the above.