JP2003080699A - Liquid droplet discharging head and method for manufacturing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet discharging head with high accuracy, high density and high reliability in which contact static electrification generated by driving is suppressed and inferiority of operation can be suppressed, and in addition, bonding with high reliability at low temperature is possible. SOLUTION: A laminating structure is provided in which the first base sheet 110 provided with an oscillation plate 111 and the second base sheet 120 provided with an electrode 121 are bonded. An insulating film 125 containing boron or both boron and phosphorus is formed on a face facing to the electrode 121 of the oscillating plate 111 and/or a face facing to the oscillating plate of the electrode. A plurality of projected parts 126 consisting of a part or the whole of elements constituting the insulating film 125 are formed on the surface of this insulating film 125. As the contact static electrification during driving is decreased by these projected parts 126, and the insulating film containing boron or both boron and phosphorus is used, size and the number (density) of the projected parts can be controlled only by adjusting heating condition of the insulating film and concentration of phosphorus and boron in the insulating film.

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,
The present invention relates to a manufacturing method thereof and an inkjet recording device using the droplet discharge head.

[0002]

2. Description of the Related Art "Electrostatic Actuator and Inkjet Head" described in JP-A-2001-10052.
In the above, the segment electrode portion of the individual electrode facing the diaphragm through the minute gap is formed of the ITO film, and the surface of this ITO film has a plurality of convex portions smaller than the gap between the electrodes. . By using the segment electrode part made of the ITO film, contact charging on the surface of the counter electrode can be reduced, so that it is possible to realize a reliable inkjet with high printing quality for a long period of time. The above-mentioned publication describes that the convex portion is formed at the same time as the ITO film, and that the convex portion is formed of a part or all of the elements constituting the ITO film.

Further, in the "ink jet head and method of manufacturing the same" described in Japanese Patent Laid-Open No. 6-23986, a first Si substrate having a nozzle and a cavity to be a pressure chamber is formed, and a second diaphragm is formed. The Si substrate is used as a component, and the diaphragm is formed by thinning the second Si substrate bonded to the first Si substrate by etching or polishing. The vibrating plate is composed of a high-concentration p-type Si layer, and in the embodiment, the second Si substrate having the high-concentration p-type Si layer and the first Si substrate are bonded by a Si-Si direct bonding method, A diaphragm is formed (= lost wafer) by leaving the p-type Si layer on the second Si substrate after bonding by alkali anisotropic etching.

Further, in the "ink jet manufacturing method" described in JP-A-9-267479, a high-concentration p-type silicon layer of a first silicon substrate having a high-concentration p-type silicon layer formed on one side, and a nozzle The second silicon substrate on which is formed is opposed to each other and is bonded by direct bonding at a temperature rising rate from room temperature of 5 ° C./minute or less to form a vibration plate.

[0005]

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, a plotter, or an image forming apparatus, ejects ink droplets. A nozzle, a liquid chamber (also referred to as a pressurized liquid chamber, a pressure chamber, a discharge chamber, an ink flow path, etc.) communicating with the nozzle, a diaphragm that forms the wall surface of the liquid chamber, and a diaphragm that faces the diaphragm. 2. Description of the Related Art There is an electrostatic inkjet head that includes an electrode and that deforms and displaces the vibrating plate by an electrostatic force to pressurize the liquid chamber ink to eject an ink droplet from a nozzle. In such an electrostatic ink jet head, fine processing is required in accordance with high speed printing and high image quality of an ink jet printer, further thinning of the diaphragm, high accuracy, and a small gap between the diaphragm and the electrode. It must be secured with high precision.

Therefore, as described in JP-A-6-23986 and JP-A-9-267479, a diaphragm processing method using an etch stop technique using a high-concentration boron diffusion layer or direct bonding is used. A method of bonding silicon substrates together has been proposed. However, in order to secure the joining reliability with direct joining, 1100 ° C
Since high temperature heating up to 1200 ° C is required and the tube of the furnace used is not heat resistant with quartz, it is necessary to use a tube with good heat resistance such as SiC, which is also limited in terms of equipment and the head manufacturing cost Get higher Further, in such an electrostatic ink jet head, there is a possibility that the vibration plate and the electrodes repeatedly contact with each other with the insulating layer sandwiched therebetween, so that the surface of the insulating layer is charged and the vibration characteristics of the vibration plate become unstable. is there. Due to this unstable vibration characteristic, there is a possibility of causing printing failure in the inkjet printer.

Therefore, as described in Japanese Patent Laid-Open No. 2001-10052, there is a method of reducing contact charging by providing a small convex portion on the surface of the ITO film of the electrode portion formed of the ITO film. Proposed. However, as described in Japanese Patent Laid-Open No. 2001-10052, forming a plurality of small convex portions by adjusting the film forming conditions of the ITO film means controlling the size and the number of the convex portions themselves. Is very difficult. Further, it is preferable that the film to be an electrode is covered with an insulating film for preventing a short circuit. As described in JP 2001-10052 A, a convex portion is formed on the surface of the ITO film when the ITO film is formed. In this case, it is difficult to completely cover the ITO film with the insulating film with good adhesion.

The present invention has been made in view of the above-mentioned circumstances, and a droplet discharge head capable of suppressing contact charging caused by driving and suppressing malfunction, and the droplet discharge head. The present invention proposes a method for easily and inexpensively manufacturing a liquid crystal, and further aims to provide a highly accurate, high density, and highly reliable droplet discharge head that enables reliable bonding at low temperature. Is.

[0009]

According to a first aspect of the present invention, there is provided a nozzle for ejecting liquid droplets, and an ejection chamber communicating with the nozzle.
A droplet discharge head, comprising: a vibrating plate forming a wall surface of the ejection chamber; and an electrode facing the vibrating plate, wherein the vibrating plate is displaced and deformed by electrostatic force to eject droplets from the nozzle. In the laminated structure, a first substrate provided with a diaphragm and a second substrate provided with the electrode are joined, and boron is provided on a surface of the diaphragm facing the electrode and / or a surface of the electrode facing the diaphragm. Alternatively, the invention is characterized in that an insulating film containing both phosphorus and boron is formed, and a plurality of convex portions formed of a part or all of the elements forming the insulating film are formed on the surface of the insulating film. As a result, the contact charging during driving is reduced by the convex portion, and further, by using boron or / an insulating film containing both phosphorus and boron as the insulating film, the heating condition of the insulating film can be improved. And the above The size and number (density) of the protrusions can be controlled simply by adjusting the concentration of phosphorus or boron in the film, and as a result, stable vibration characteristics can be obtained and a droplet discharge head capable of stable droplet discharge can be obtained. I am able to provide it.

According to a second aspect of the present invention, in the first aspect of the present invention, both the first substrate having the diaphragm and the second substrate having the electrodes are made of silicon substrates, and both substrates are made of phosphorus and boron. It is characterized in that it is joined using a silicon oxide film containing silicon, which utilizes the fact that the silicon oxide film containing phosphorus and boron reflows at a low temperature, and The use of the silicon oxide film for joining the two substrates enables strong joining at low temperatures.

According to a third aspect of the invention, in the first or second aspect of the invention, the convex portion is formed at the same time as the step of joining the first substrate and the second substrate. The process cost can be reduced by simultaneously forming the convex portions when the substrate and the second substrate are joined.

The invention of claim 4 is characterized in that, in any of the inventions of claims 1 to 3, the sum of the phosphorus concentration and the boron concentration of the insulating film is set to 9 wt% or more. The number of protrusions per piece / cm ² or more can be easily formed.

According to a fifth aspect of the present invention, in manufacturing the droplet discharge head according to any of the first to fourth aspects, the first substrate and the second substrate are superposed and bonded by heat treatment at 900 ° C. to 1050 ° C. It is characterized by 900
The joints can be simultaneously formed by heat treatment at ℃ to 1050 ℃, and even when a high-concentration boron layer is used, the redistribution of boron is suppressed and the thickness of the diaphragm is controlled with high accuracy. It can be done and the tube of the furnace used is SiC
It is not necessary to use a tube having good heat resistance such as, and the process cost can be suppressed.

According to a sixth aspect of the invention, in the fifth aspect of the invention, after the heat treatment, the temperature is maintained at 950 ° C. or higher, and then 90
The temperature decrease rate up to 0 ° C is 10 ° C / min or less, and the temperature decrease rate from at least 900 ° C to 800 ° C is 50 ° C / min or more. The thermal cycle is maintained at 950 ° C or more. After that, the temperature decrease rate up to 900 ° C is gradually cooled to 10 ° C / minute or less, and the temperature decrease rate from 900 ° C to 50 ° C / minute.
By quenching for more than a minute, the size is 0.1
It is possible to form a convex portion having a size of μm or less and a small size variation, and as a result, it is possible to provide a droplet discharge head capable of obtaining stable vibration characteristics and capable of stable droplet discharge.

According to a seventh aspect of the invention, an ink jet recording apparatus is constructed using the droplet discharge head according to any one of the first to fourth aspects, and ink is discharged by using the droplet discharge head according to the present invention. The characteristics and durability are improved,
This is intended to improve image quality and reliability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an exploded perspective view of an essential part showing an embodiment of a droplet discharge head according to the present invention, and FIG. 2 is a schematic sectional configuration view of the essential parts of an assembled droplet discharge head. Three
Is a top view with the nozzle plate removed, FIG.
FIG. 4 is an enlarged view of the surface of an insulating film (silicon oxide film).

The droplet discharge head according to the present embodiment is of a type that discharges ink droplets by changing the volume of the discharge chamber communicating with the nozzle by attracting and vibrating the diaphragm using electrostatic force. Is. Of course, it is also possible to adopt a type in which the volume of the ejection chamber communicating with the nozzle is changed by using a piezoelectric element or the like to eject ink droplets, and the heating element is used to remove the ink in the ejection chamber. It is also possible to adopt a type that expands and ejects ink droplets. Further, in this embodiment, the side shooter type in which the ink droplets are ejected from the nozzle holes provided in the upper surface of the substrate, but the edge shooter type in which the ink droplets are ejected from the nozzle holes provided in the end portion of the substrate may be used.

First, the structure of the droplet discharge head will be described with reference to FIGS. The droplet discharge head 100 according to the present embodiment has a laminated structure in which three substrates 110, 120 and 130 are stacked. 110 is a silicon substrate which is a first substrate, 120 is an electrode silicon substrate which is a second substrate, and 130 is a nozzle plate which is a third substrate. The silicon substrate 110 is made of, for example, single crystal silicon having a (110) plane orientation, a bottom wall of the ejection chamber 112 (ink chamber) that functions as the vibrating plate 111, and a common ink for supplying ink to each ejection chamber 112. It has a concave portion which becomes the chamber 113. Further, on the lower surface of the silicon substrate 110, that is, the surface of the vibrating plate 111 facing the electrode, in order to prevent a short circuit between the vibrating plate 111 and an individual electrode 121 described later when the droplet discharge head 100 is driven, a silicon oxide film The insulating layer 114 is formed.

The nozzle plate 130 bonded to the upper surface of the silicon substrate 110 is made of, for example, glass or plastic, stainless steel or Kovar (Fe29-Ni-17C).
The discharge chamber 11 is made of a metal such as o) or a silicon substrate.
The number of nozzles 131 corresponding to the number of discharge chambers is formed at a position corresponding to 2. Further, a fluid resistance 132 is formed so as to connect the ejection chamber 112 of the substrate 110 and the common ink chamber 113. By joining the nozzle plate 130 and the silicon substrate 110, the ejection chamber 112, the fluid resistance 132, and the common ink chamber 113 communicating with the nozzle 131 are defined.

The electrode silicon substrate 120 bonded to the lower surface of the silicon substrate 110 is, for example, a silicon substrate having a thickness of 625 μm, and a thermal oxide film 122 is formed on the upper surface to a thickness of 0.6 μm. An individual electrode 121 is formed on the oxide film 122, an insulating film 123 made of a silicon oxide film is formed on the individual electrode, and a concave portion 124 that forms a gap G is provided in the insulating film 123.
A low melting point silicon oxide film layer 125 containing boron or both phosphorus and boron is formed on the insulating film 123. Here, since the silicon oxide film 125 exhibits a softening point at a lower temperature than a non-doped silicon oxide film, bonding at a low temperature becomes possible. In the present specification, “1050
"Joining at a temperature not exceeding ℃" is called "joining at low temperature". After the silicon oxide film 125 is formed, the silicon oxide film 125 is reflowed by a heat treatment at a temperature equal to or higher than the softening point, and the surface property is evaluated using an AFM. Surface property is obtained. still,
Although the silicon oxide film 125 is formed on the electrode substrate 120 here, it may be formed on the silicon substrate 110 (for example, on the silicon oxide film 114). Further, on the surface of the silicon oxide film 125, the line B- in FIG.
As shown by enlarging the B line portion, the convex portion 126 is formed. In the present invention, the presence of the convex portion 126 reduces the contact area between the insulating film 114 and the silicon oxide film 125 during driving, and as a result, contact charging is suppressed,
Stable ink ejection is possible for a long time.

Electrode Silicon substrate 120 and silicon substrate 1
The recesses (vibration chambers) 124 are formed by joining 10 and the individual electrodes 121 are arranged at respective positions corresponding to the respective vibration plates 111. In addition, the substrate 110 and the substrate 12
An ink supply port 127 is provided penetrating 0. A common ink chamber 113 is provided above the ink supply port 127. In addition, here, the electrode silicon substrate 12
0 and the silicon substrate 110 are bonded together, the maximum gap (gap) G between the electrode 121 and the diaphragm 111 in the recess 124 is
Is 0.25 μm. The driver 140 is connected to the common electrode 115 and each individual electrode 121 by bonding a lead wire, for example, and the droplet discharge head (inkjet head) 100 shown in FIG. 2 can be driven.

Further, by connecting an ink supply pipe to the ink supply port 127 of the ink jet head 100 by adhering it, the common ink chamber 113, the ejection chamber 112, etc. are supplied from an ink tank (not shown) through the ink supply port 127. The filled ink can be filled. In addition,
The ink used is prepared by dissolving or dispersing a surfactant such as ethylene glycol and a dye or pigment in a main solvent such as water, alcohol or toluene. Furthermore, if a heater or the like is attached to the inkjet head, hot melt ink can also be used.

For each individual electrode 121, the driver 140
Thus, for example, by applying a positive voltage pulse, the electrode 121
When the surface of each is charged to a positive potential, the corresponding vibration plate 111
The bottom surface of is charged to a negative potential. Therefore, the diaphragm 11
1 is attracted by the electrostatic force and bends in a direction in which the distance between the electrode 1 and the individual electrode 121 is narrowed. At this time, the vibration plate 111 bends, so that ink is supplied from the common ink chamber 113 to the ejection chamber 112 via the orifice 132. Next, when the voltage pulse applied to the individual electrode 121 is turned off and the accumulated charge is discharged, the diaphragm 111 restores to its original position. Due to this restoration operation, the internal pressure of the ejection chamber 112 rapidly rises, and ink droplets are ejected from the nozzle holes 131.

The diaphragm 111 in the ink jet head of this embodiment is a high concentration p-type impurity layer,
The high-concentration p-type impurity layer has the same thickness as the desired diaphragm thickness. Although boron, gallium, aluminum or the like is used as the impurity forming the high-concentration p-type impurity layer, boron is generally used as the impurity forming the p-type impurity layer in the field of semiconductors. Also made boron an impurity. As for the etching rate in Si etching with alkali, when the dopant is boron, the etching rate becomes very small in a high concentration region. In this embodiment, by utilizing this, the diaphragm forming region is a high-concentration boron-doped layer, and the etching rate at the time when the boron-doped layer is exposed when the ejection chamber and the ink cavity are formed by alkali anisotropic etching. The vibration plate 111 is manufactured to have a desired plate thickness by a so-called etch stop technique, which is extremely small.

Example 1 Next, FIG. 5 (a sectional view taken along the line VV in FIG. 3).
The method for manufacturing the inkjet head of the present invention will be described with reference to FIG. Note that FIG. 5A to FIG. 5D
Is a diagram showing a manufacturing process of the second substrate 120 on which the individual electrodes are formed, and FIGS. 5E to 5G show the first substrate 110 on which the vibration plate is formed on the second substrate 120. 5H shows a manufacturing process of the third substrate 130 which is a nozzle plate formed on the first substrate 110.

Step a (FIG. 5A) First, a thermal oxide film 122 having a thickness of 0.6 μm is formed on one side of a silicon substrate 120 having a thickness of 625 μm (100), and a polysilicon film 121 a is formed on the entire surface. 1 by CVD method
Then, it is deposited to a thickness of 00 nm, phosphorus or arsenic, boron or BF ₂ is ion-implanted, and a heat treatment for activation is performed. Next, a tungsten silicide film 121b is deposited by a 200 nm sputtering method. Before sputtering the tungsten silicide film, the surface of the polysilicon film is reverse-sputtered (etched) with Ar to be cleaned (: removal of natural oxide film, etc.)
Since high reliability can be secured for the adhesion of the film by doing so, it is desirable to use a multi-chamber sputtering apparatus and perform the cleaning of the deposition surface and the continuous processing of the deposition. The tungsten silicide film 121b and the polysilicon film 121a are patterned by a well-known photolithography technique and dry etching technique, and the tungsten silicide film 121b and the polysilicon film 121a are patterned.
An individual electrode 121 composed of is formed. Although a stacked body of polysilicon and tungsten silicide is used here as the individual electrode 121, a single layer film may be used, or a refractory metal such as TiN or another refractory metal silicide may be used.

Subsequently, by depositing a silicon oxide film 123 as a protective insulating film by the CVD method, the spaces between the individual electrodes 121 are filled with the silicon oxide film 123, and the surface of the individual electrode 121 has a thickness of 550 nm. 123 is formed. A recess Q is formed on the surface of the silicon oxide film 123 due to the influence of the embedded shape during the separation of the individual electrodes.

Step b (FIG. 5B) The surface of the silicon oxide film 123 is polished. This polishing is performed by CMP (chemical-mechanical).
-Polishing), which is a technique used for planarizing a substrate in a semiconductor process. 1 in CMP
After polishing with 50 nm, the recess Q disappears and the silicon substrate 120 is flattened, and the film thickness of the silicon oxide film 123 on the individual electrode becomes 400 nm. Further, the surface roughness of the silicon oxide film 123 before polishing was evaluated by AFM, and the surface roughness: Ra value was about 1 to 2 nm. Is 0.3n
Since it is m or less, a surface property advantageous for obtaining very good bondability can be obtained.

Step c (FIG. 5C) Next, a carved portion 124 for forming a gap is formed by etching the silicon oxide film 123. The engraved portion 124 is formed in a non-parallel state by etching the resist shape by photolithography using a mask having a gradation pattern so that the resist shape is transferred using Ar gas or the like. Was formed as follows. Engraving part 12
The depth of the bottom of 4 is 0.25 μm, and the silicon oxide film 123 is 0.15 μm thereabove.

Step d (FIG. 5D) Next, a silicon oxide film 125 made of a BPSG film (boron concentration 4.2 wt%, phosphorus concentration 0.8 wt%) is formed by CVD.
Method is used to deposit 50 nm. The important point is that by including both phosphorus and boron in the silicon oxide film, the melting point of the silicon oxide film is lowered to give the silicon oxide film reflowability, and a precipitate to form the convex portion 126 is formed. It is possible. Further, the silicon oxide film 125 was heat-treated at a temperature equal to or higher than the melting point (here, 1000 ° C., nitrogen gas atmosphere) for reflow. The surface property of the silicon oxide film 125 after the reflow is evaluated by AFM and the surface property is Ra: 0.3 nm or less, and a surface property capable of very good bonding is obtained.

In the heat treatment here, the entire heat cycle is performed in an N ₂ atmosphere so as to prevent the formation of precipitates which become convex portions. Precipitates can be generated on the surface of the BPSG film by devising the heat cycle here (for example, by using oxygen as a gas at the time of temperature rise). Since there is a precipitate, it becomes difficult to bond the substrates to each other later. In this case, if a precipitate is to be generated, it is necessary to perform some patterning beforehand so that the silicon oxide film 125 does not exist on the bonding surface.

Step e (FIG. 5 (E)) 520 μm-thick Si substrate 1 having (110) plane orientation
The coating diffusion method was used to diffuse boron to 10. Si
B on the substrate 110₂O₃Dispersed in an organic solvent
And heat treatment (1125 ° C, 40 minutes)
The boron is diffused to form the high-concentration boron diffusion layer 116.
(Note that the diffusion method is BBr in addition to this embodiment. ₃Qi using
Phase diffusion method, ion implantation method, solid diffusion method, etc. may be used.
I). After that, B on the surface of the Si substrate₂O₃Layer with hydrofluoric acid
Remove. B₂O₃Compound layer of silicon and boron under the layer
Has been formed and if it is to be removed, it may be oxidized.
With and can be removed with hydrofluoric acid. But this
Even if the compound layer is oxidized with hydrofluoric acid to remove boron,
Since the diffused silicon surface of is roughened,
It cannot be joined by direct joining performed later. Therefore, CMP polishing
Surface property that can be directly bonded by using (5 μm □ using AFM)
Ra = 0.15 nm or less) was obtained by measuring the area. this
Substrate 110 (high
Good by thermally oxidizing the boron concentration diffusion layer 116)
Oxide film 1 with excellent surface properties (Ra = 0.20 nm or less)
14 was formed. Here, the oxide film 114 protects the diaphragm.
It will function as an insulating film. Note that the diaphragm is protected
The oxide film 114, which is an insulating film, also protects the electrode side.
If an insulating film is formed, it may be possible to reduce the film thickness.
(For example, a silicon oxide film is used as a protective insulating film for the electrodes.
When the thickness of 100 nm or more is formed, the oxide film 1
14 should have a thickness of about 30 to 50 nm).

Step f (FIG. 5 (F)) The second substrate 120 formed in the steps a to d and the first substrate 110 formed in the step e are bonded. Pre-bonding was completed by cleaning and drying each substrate using a substrate cleaning method such as sulfuric acid-hydrogen peroxide mixture or ammonia-hydrogen peroxide mixture, and then pressing both substrates under reduced pressure while overlapping them in the atmosphere. Further, thereafter, the bonded wafers are heat-treated (950 ° C., 1 hour) in a nitrogen gas atmosphere to bond the both substrates. At this time, a deposit is generated on the surface of the silicon oxide film 122, and this deposit becomes the convex portion 126. As a result of analysis, the precipitate obtained in this example was mainly composed of boron, phosphorus and oxygen. Moreover, as a result of analyzing the silicon oxide film 125, phosphorus was not detected in the vicinity of the precipitate and was detected in the portion corresponding to the joint. This means that phosphorus in the silicon oxide film 125 has been consumed for forming precipitates.

One of the important points in this embodiment is that the convex portion 126 is formed at the same time when the two substrates are joined together, which is a point that the process cost can be reduced.
Further, as another important point, as described in step d, the melting point of the silicon oxide film 125 is lowered, and a strong joint having high joint reliability at a relatively low temperature (here, 950 ° C.) is obtained. This is possible. The heat treatment at the time of joining is: 900 ° C. as a temperature sufficient to generate precipitates
The above is desirable. -When a high-concentration boron layer is used for the diaphragm, the redistribution of boron is suppressed, the thickness of the diaphragm is controlled with high accuracy, and the furnace tube used is a tube with good heat resistance such as SiC. Is not necessary, and 1050 ° C. or lower is desirable to reduce the process cost.

Step g (FIG. 5 (G)) Next, a substrate 520 having a thickness of 520 μm is formed with a thickness of 100 μm.
Thin by polishing, photolithography technology,
Using the silicon nitride film patterned by the dry etching technique as a mask, the substrate 11 is heated with a 10 to 30 wt% potassium hydroxide aqueous solution at a temperature of 80 to 90 ° C.
0 is anisotropically etched. When the boron concentration reaches a depth of 1E20 / cm ³ , the etching is stopped (the etching rate is extremely reduced), and the vibration plate 111 and the discharge chamber 112 made of the high-concentration boron-doped silicon layer 116 are formed. . As described above, by using the etch stop technology using the high-concentration boron layer and performing the bonding at the temperature at which the re-diffusion of boron does not occur, it is possible to form the diaphragm whose thickness is controlled with high accuracy. I can.

Step h (FIG. 5 (H)) Finally, the ink jet head is completed by joining the nozzle 131 and the nozzle plate 130 having the fluid resistance formed thereon with an adhesive or the like.

Embodiment 2 Next, a method of manufacturing an ink jet head according to another embodiment of the present invention will be described with reference to FIG. (1): Process a to process c (FIGS. 5A to 5C)
Is the same as in the first embodiment. (2): In step d (FIG. 5D), in the second embodiment, the silicon oxide film 125 made of the BPSG film is deposited to a thickness of 50 nm by the CVD method. Here, several kinds of BPSG films were formed using the boron concentration and phosphorus concentration of the BPSG film as parameters. After that, the second step is performed in the same manner as in the step d.
The substrate 120 of is manufactured. (3): In steps e, f, and g, the first substrate 110 is manufactured in the same manner as in Example 1, the second substrate 120 and the first substrate 110 are bonded, and then the diaphragm 111 and Discharge chamber 1
After forming No. 12, the number of precipitates as convex portions (density: pieces / cm ² ) was examined using a differential interference microscope or the like.

FIG. 6 is a graph showing the results of examining the number of the deposits (relationship between the number of deposits and the boron concentration and phosphorus concentration) of the ink jet manufactured in Example 2. From FIG. 6, the boron concentration and the phosphorus concentration are shown. Is about 9 wt% or more and 10,000
It is possible to form the precipitates of the number of pieces / cm ² or more, that is, the convex portions 126. This means that even if the area of the engraved portion 124 becomes smaller due to the miniaturization of the inkjet head, a plurality of convex portions can be reliably formed in the gap, and as a result, stable vibration characteristics and stable droplet ejection are possible. It is possible to provide a droplet discharge head compatible with high speed and high image quality printing.

Embodiment 3 Next, a method of manufacturing an ink jet head according to still another embodiment of the present invention will be described with reference to FIG. (I): Steps a to d of Example 1 (FIGS. 5A to 5)
The second substrate 120 and the first substrate 110 are manufactured in the same manner as in (E). (II): Next, the second substrate 120 and the first substrate 110 formed in (I) are bonded. Pre-bonding was completed by cleaning and drying each substrate using a substrate cleaning method such as sulfuric acid-hydrogen peroxide mixture or ammonia-hydrogen peroxide mixture, and then pressing both substrates under reduced pressure while overlapping them in the atmosphere. After that, the bonded wafers are heat-treated in a nitrogen gas atmosphere to bond the two substrates (FIG. 5F).

In the above heat treatment, the particle size of the precipitate (projection 126) of "a sample which was held at 950 ° C. for 1 hour and then gradually cooled to 800 ° C. at a temperature lowering rate of 10 ° C./min or less" was examined. The particle size X shown in was 0.55 to 0.15 μm, while “holding at 950 ° C. for 1 hour, gradually cooling to 900 ° C. at a temperature decrease rate of 10 ° C./min or less, The particle size X of the precipitates of the "sample rapidly cooled at a cooling rate of 50 ° C / min" was uniform in size from 0.05 µm to 0.08 µm.

Regarding the grain height, the former sample was 0.05 to 0.08 μm, and the latter sample was 0.05 μm to 0.02 μm.
The difference between the samples was 6 μm, which was smaller than the particle size X, but the latter was more uniform. This means that precipitates are formed when cooled from high temperatures, and at high temperatures (here 950
The lower the temperature (90
It is considered that the particle size increases (0 ° C to 800 ° C). Also,
In the latter case, if the rate of temperature decrease from 900 ° C. is 50 ° C./min or more, almost the same result is obtained.

As described above, generation of large precipitates can be suppressed by controlling the rate of temperature decrease during heat treatment, in particular by increasing the rate of temperature decrease from 900 ° C. (rapid cooling), forming convex portions with small size variation. I can. As a result, it is possible to provide a droplet discharge head that can obtain stable vibration characteristics and can stably discharge droplets.

Embodiment 4 Hereinafter, an embodiment of an ink jet recording apparatus according to the present invention will be described with reference to FIGS. 7 and 8. 7. FIG. 7 is a perspective explanatory view of a printing mechanism unit having the inkjet head according to the present invention, and FIG. 8 is a side view explanatory diagram of an inkjet recording apparatus having the printing mechanism unit shown in FIG.
The inkjet recording apparatus 1 is a printing apparatus including a carriage that is movable in the main scanning direction inside the recording apparatuses 1 and 1, a recording head including an inkjet head mounted on the carriage, and an ink cartridge that supplies ink to the recording head. A mechanism 2 and the like can be accommodated, and a paper feeding cassette (or a paper feeding tray) 4 capable of loading a large number of papers 3 can be detachably attached to the lower portion of the recording device 1 from the front side. Further, the manual feed tray 5 for manually feeding the paper 3 can be opened and closed, the paper 3 fed from the paper feed cassette 4 or the manual feed tray 5 is taken in, and the desired image is printed by the printing mechanism unit 2. After recording
The paper is discharged to the paper discharge tray 6 mounted on the rear surface side.

The printing mechanism unit 2 slides the carriage 13 in the main scanning direction (the direction perpendicular to the paper surface in FIG. 8) by the main guide rod 11 and the sub guide rod 12 which are guide members which are horizontally mounted on the left and right side plates (not shown). Hold it at will, this carriage 1
3 is a head 14 formed of an inkjet head that ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk) in a direction that intersects a plurality of ink ejection ports with the main scanning direction. And are mounted so that the ink droplet ejection direction faces downward. Further, each ink cartridge 15 for supplying each color ink to the head 14 is replaceably mounted on the carriage 13.

The ink cartridge 15 has an atmosphere port communicating with the atmosphere above, a supply port supplying ink to the ink jet head below, and a porous body filled with ink inside. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of.

Although the heads 14 of the respective colors are used as the recording heads in the present embodiment, a single head having nozzles for ejecting ink droplets of the respective colors may be used. Furthermore, head 1
The ink jet head used as No. 4 is a piezo type that presses ink through a vibration plate that forms a wall surface of a liquid chamber with an electromechanical conversion element such as a piezoelectric element, or a bubble type that presses ink by generating bubbles by a heating resistor. Alternatively, it is possible to use an electrostatic type or the like in which the diaphragm is displaced by the electrostatic force between the diaphragm forming the wall surface of the ink flow path and the electrode facing the diaphragm to press the ink. An electrostatic inkjet head is used.

Here, the carriage 13 is slidably fitted to the main guide rod 11 on the rear side (downstream side in the sheet conveying direction), and the front side (upstream side on the sheet conveying direction) in the sub guide rod 1.
2 is slidably mounted. Then, since the carriage 13 is moved and scanned in the main scanning direction, the main scanning motor 1
A timing belt 20 is stretched between a drive pulley 18 and a driven pulley 19 which are rotatably driven by 7, and the timing belt 20 is fixed to the carriage 13. It is driven back and forth.

On the other hand, the paper 3 set in the paper feed cassette 4
For feeding the paper 3 to the lower side of the head 14, a paper feed roller 21 and a friction pad 22 for separating and feeding the paper 3 from the paper feed cassette 4, and a guide member 23 for guiding the paper 3.
A transport roller 24 that reverses and transports the fed paper 3, a transport roller 25 that is pressed against the peripheral surface of the transport roller 24, and a tip roller 26 that defines the feed angle of the paper 3 from the transport roller 24. Is provided. The transport roller 24 is rotationally driven by the sub-scanning motor 27 via a gear train.

A print receiving member 29, which is a paper guide member for guiding the paper 3 sent out from the carrying roller 24 below the recording head 14 in correspondence with the range of movement of the carriage 13 in the main scanning direction, is provided. There is. A conveying roller 31 and a spur 32, which are rotationally driven to send out the sheet 3 in the sheet discharging direction, are provided on the downstream side of the printing receiving member 29 in the sheet conveying direction.
Further, a paper discharge roller 33 and a spur 34 for sending the paper 3 to the paper discharge tray 6 and guide members 35 and 36 forming a paper discharge path are provided.

At the time of recording, the recording head 14 is driven according to an image signal while moving the carriage 13 to eject ink onto the stopped paper 3 to record one line, and the paper 3 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 sheet 3 has reached the recording area, the recording operation is terminated and the sheet 3 is ejected.

A recovery device 37 for recovering the ejection failure of the head 14 is arranged at a position outside the recording area on the right end side of the carriage 13 in the moving direction. The recovery device has a cap means, a suction means, and a cleaning means. The carriage 13 is provided with the recovery device 37 while waiting for printing.
The head 14 is moved to the side and the head 14 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant, and stable ejection performance is maintained.

When ejection failure occurs, the ejection port of the head 14 is sealed by the capping means, and the bubbles and the like are sucked out from the ejection port through the tube and the ink is ejected from the ejection port. Is removed by the cleaning means and the ejection failure is recovered. 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.

[0053]

The present invention is provided with a nozzle for discharging liquid droplets, a discharge chamber communicating with the nozzle, a diaphragm forming a wall surface of the discharge chamber, and an electrode facing the diaphragm. In a droplet discharge head that displaces and deforms a diaphragm by electrostatic force to discharge droplets from the nozzle, a first substrate provided with the diaphragm and a second substrate provided with the electrode have a laminated structure, An insulating film containing boron or both phosphorus and boron is formed on the surface of the vibration plate facing the electrode and / or the surface of the electrode facing the vibration plate, and the surface of the insulating film is By forming a plurality of convex portions formed of a part or all of the elements forming the insulating film, contact charging during driving is reduced by the convex portions, and an insulating film containing boron or / both phosphorus and boron is used. Because the above The size and number (density) of the convex portions can be controlled simply by adjusting the heating conditions of the edge film and the concentration of phosphorus and boron in the insulating film, and as a result, stable vibration characteristics can be obtained and stable droplet ejection can be achieved. It is possible to provide a possible droplet discharge head.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of essential parts showing an embodiment of a droplet discharge head according to the present invention.

FIG. 2 is a schematic cross-sectional configuration diagram of a main part of the assembled droplet discharge head.

FIG. 3 is a top view when a nozzle plate is removed.

FIG. 4 is an enlarged view of a surface of an insulating film (silicon oxide film).

FIG. 5 is a process chart for explaining a method of manufacturing an inkjet head according to the present invention.

FIG. 6 is a diagram in which the produced inkjet deposits are examined.

FIG. 7 is a perspective explanatory view of a printing mechanism unit equipped with an inkjet head according to the present invention.

8 is a side view of an ink jet recording apparatus equipped with the printing mechanism section shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording device, 2 ... Printing mechanism part, 3 ... Paper, 4 ... Paper feed cassette, 5 ... Manual feed tray, 6 ... Paper ejection tray, 11 ... Main guide rod, 12 ... Slave guide rod, 13 ... Carriage, 14 ... Recording head, 15 ... Ink cartridge, 1
7 ... Main scanning motor, 18 ... Driving pulley, 19 ... Followed pulley, 20 ... Timing belt, 21 ... Paper feeding roller, 22
... Friction pad, 23 ... Guide member, 24 ... Conveying roller, 25 ... Conveying roller, 26 ... Tip roller, 27 ... Sub scanning motor, 29 ... Printing receiving member, 31 ... Conveying roller, 32
... spur, 33 ... ejection roller, 34 ... spur, 35, 36 ...
Guide member, 37 ... Recovery device, 100 ... Droplet ejection head, 110 ... Silicon substrate, 111 ... Vibration plate, 112 ...
Discharge chamber, 113 ... Common ink chamber, 114 ... Insulating layer, 11
5 ... Common electrode, 116 ... High concentration boron diffusion layer, 120 ...
Electrode silicon substrate, 121 ... Individual electrode, 121a ... Polysilicon film, 121b ... Tungsten silicide film, 1
22 ... Thermal oxide film, 123 ... Insulating film, 124 ... Recessed part, 12
5 ... Silicon oxide film layer, 126 ... Convex portion, 127 ... Ink supply port, 130 ... Nozzle plate, 131 ... Nozzle, 1
32 ... Fluid resistance, 140 ... Driver.

Claims (7)

[Claims] 1. A nozzle for discharging droplets, a discharge chamber in which the nozzle communicates, and a vibrating plate forming a wall surface of the discharge chamber.
A droplet discharge head, comprising: an electrode facing the vibrating plate, wherein the vibrating plate is displaced and deformed by electrostatic force to eject droplets from the nozzle, the first substrate having the vibrating plate, and the electrode. A laminated structure in which a second substrate is joined, and an insulating film containing boron or both phosphorus and boron is formed on a surface of the diaphragm facing the electrode and / or a surface of the electrode facing the diaphragm. The droplet discharge head is characterized in that a plurality of convex portions are formed on the surface of the insulating film, the convex parts being formed of a part or all of the elements forming the insulating film. 2. The first substrate having the diaphragm and the second substrate having the electrodes are both silicon substrates.
The droplet discharge head according to claim 1, wherein both substrates are bonded together by using a silicon oxide film containing both phosphorus and boron. 3. The droplet discharge head according to claim 1, wherein the convex portion is formed at the same time as the step of joining the first substrate and the second substrate. 4. The droplet discharge head according to claim 1, wherein the sum of the phosphorus concentration and the boron concentration of the insulating film is 9 wt% or more. 5. The method of manufacturing a droplet discharge head according to claim 1, wherein the first substrate and the second substrate are superposed and bonded by heat treatment at 900 ° C. to 1050 ° C. And a method for manufacturing a droplet discharge head. 6. In the heat treatment, the temperature lowering rate up to 900 ° C. after holding at 950 ° C. or higher is 10 ° C./minute or less,
Temperature decrease rate from at least 900 ℃ to 800 ℃ is 50 ℃
6. The method for manufacturing a droplet discharge head according to claim 5, wherein the ratio is not less than 1 / minute. 7. An ink jet recording apparatus equipped with an ink jet printer head, wherein the ink jet printer head is the droplet discharge head according to any one of claims 1 to 4.