JPH10181015A - Ink-jet recording head and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict a warp or distortion of a substrate, highly accurately pattern elements, easily fit a chip having required elements to a base, and improve adhesion of the substrate and a nozzle plate. SOLUTION: There are provided a piezoelectric body element 20 formed on a silicon substrate 11, an ink cavity 18 formed at a position corresponding to the piezoelectric body element 20 formed on the silicon substrate 11, and a nozzle plate 26 having a discharge opening 25 through which the ink stored in the ink cavity 18 is discharged. An intermediate film 17 having nearly the same thermal expansion coefficient as a lower electrode 14 constituting the piezoelectric body element 20 is interposed between the silicon substrate 11 and nozzle plate 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head and a method of manufacturing the same, and more particularly to an ink cavity containing ink by applying electric energy to a piezoelectric element to vibrate or fluctuate a diaphragm. The present invention relates to an ink jet recording head that ejects and discharges ink by applying pressure to a recording medium, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Heretofore, as a driving source for ink ejection, that is, an element made of lead zirconate titanate (hereinafter referred to as "PZT") has been used as an element for converting electrical energy into mechanical energy. There is an ink jet recording head that has been used.

The ink jet recording head generally includes a substrate having a large number of individual ink passages (ink cavities, ink reservoirs, etc.) formed therein, a diaphragm attached to the substrate so as to cover all the individual ink passages, and And a piezoelectric element formed of a lower electrode, a PZT film, and an upper electrode formed at each portion corresponding to the individual ink passage of the vibration plate.

In this ink jet type recording head, ink contained in an individual ink passage is ejected from the individual ink passage by a pressure generated by vibrating or displacing a diaphragm by applying an electric field to a piezoelectric element. It is configured such that it can be pushed out or ejected from a hole (ink ejection port) of a nozzle plate provided on the side.

In this ink jet recording head, a silicon wafer (hereinafter, referred to as "wafer") is used as a substrate.
Is used, first, patterning for forming a plurality of piezoelectric elements on a wafer is performed, and then the wafer is divided into chips.

In this ink jet recording head, a piezoelectric element is usually formed by the following steps. That is, a lower electrode forming film, a PZT film, and an upper electrode forming film made of platinum or the like are formed on a wafer serving as a substrate via a silicon oxide film (thermal oxide film).

Next, a photoresist is coated on the upper electrode formation region on the upper electrode formation film and patterned, and the upper electrode formation film and the PZT film are etched using the photoresist as a mask. Thereafter, a photoresist is formed in the lower electrode forming region of the substrate and patterned, and the lower electrode forming film is etched using the photoresist as a mask.

Here, if a material having low reactivity such as platinum is used as a material for forming the lower electrode forming film, when the upper electrode forming film and the PZT film are etched, the lower electrode once over-etched is formed. There has been a problem that the electrode material is redeposited (residual residue), which causes a leak or short circuit between the electrodes. Therefore,
To prevent this redeposition, the photoresist is formed in a trapezoidal shape with a tapered side wall.

In the structure of the ink jet recording head,
If the partition walls of the ink cavity do not have sufficient rigidity, when the ink cavity is pressurized, the partition walls bend and a problem arises in that sufficient pressure for ink ejection cannot be obtained. Further, as a result that the pressure easily propagates to the adjacent ink cavities, there is a problem that the characteristic of ejecting the ink is changed by ON / OFF of the adjacent element.

Therefore, in order to increase the rigidity of the partition wall of the ink cavity, the thickness of the wafer has been reduced.

[0011]

However, the inventors of the present invention have made extensive studies and found that when the thickness of the wafer is reduced,
When the lower electrode forming film is formed on the wafer, the wafer tends to be warped or distorted due to the difference between the thermal expansion coefficient of the wafer and the lower electrode forming film. As described above, when the wafer is warped or distorted, a patterning mask (photoresist or the like) for forming the upper electrode, the PZT film, and the lower electrode cannot be formed in a uniform shape. There is a problem that the reproducibility of the shape of the element or the accuracy is reduced. Further, as described above, there is also a problem that it is difficult to prevent redeposition (occurrence of residue) depending on the shape of the photoresist.

On the other hand, there is a residual stress in the layer laminated on the substrate, and the residual stress may cause a warp or a distortion in the wafer. There is room for improvement.

Therefore, the present invention prevents the wafer from being warped or distorted so that the patterning of the elements can be performed with good reproducibility.
It is an object of the present invention to provide an ink jet recording head with high precision.

Another object of the present invention is to provide an ink jet recording head in which a desired element is formed and a chip separated from a wafer can be easily fitted to a base. Still another object is to provide an ink jet recording head in which the adhesiveness between a substrate on which an ink cavity is formed and a nozzle plate is improved. Still another object of the present invention is to provide a method for manufacturing these ink jet recording heads.

[0015]

In order to achieve this object, the present invention provides a substrate having an individual ink passage formed therein, a piezoelectric element formed in each of the portions corresponding to the individual ink passage, An ink jet recording head comprising: an ink ejection unit for ejecting ink in the individual ink passage; wherein an intermediate film having a thermal expansion characteristic similar to that of a lower electrode forming the piezoelectric element is provided on the ink ejection unit side. It is characterized by being provided in.

In one embodiment of the present invention, a piezoelectric element formed on a first surface of a substrate, an ink cavity formed at a position corresponding to the piezoelectric element on the substrate, And a nozzle means formed on a second surface opposite to the surface of the substrate and having an ejection port for ejecting the ink contained in the ink cavity. An ink jet type recording head comprising an intermediate film between the second surface and the nozzle means, which has the same thermal expansion characteristic as the lower electrode constituting the piezoelectric element. .

In the ink jet type recording head having such a structure, a film having a similar thermal expansion characteristic is formed on both surfaces of the substrate, so that the lower electrode forming material and the substrate have different thermal expansion characteristics. However, the warpage and distortion of the substrate caused by this will be offset by the intermediate film and the lower electrode.

That is, the thermal expansion characteristics of the films formed on the first surface side and the second surface side of the substrate are determined by the physical deformation of the substrate such as warpage, distortion, or twist on the substrate. The same range is set until the pattern error of the element configuration and the pattern accuracy are not substantially affected.

In the present invention, the fact that the thermal expansion characteristics are substantially the same means that the difference between the thermal expansion coefficients of the films and layers to be compared is within ± 10%.

Here, one aspect of the thermal expansion characteristic is the thermal expansion coefficient. In particular, when the thickness of the above-described intermediate film is substantially the same as the thickness of the lower electrode, the intermediate film may be made of a material having substantially the same thermal expansion coefficient as the lower electrode. on the other hand,
Another aspect of the thermal expansion characteristic is the product of the coefficient of thermal expansion and the thickness of the target film. That is, the product of the film thickness of the lower electrode and its thermal expansion coefficient should be approximately the same as that of the lower electrode. In short, in the present invention, the thermal expansion characteristic is a means or an element for balancing the compressive stress of the film or layer to be compared. Therefore, the present invention is not limited to the two aspects described above. Elements and means of thermal expansion characteristics suitable for the composition and form of the film or layer may be appropriately selected or designed.

More preferably, the intermediate film is made of a lower electrode forming material. By doing so, in addition to the above advantages, the adhesiveness between the substrate and the nozzle plate is also improved.
Further, it is preferable that the lower electrode and the intermediate film are formed to have substantially the same thickness.

Further, the present invention provides a piezoelectric element formed on a first surface of a substrate, an ink cavity formed on the substrate at a position corresponding to the piezoelectric element, and a first surface of the substrate. A nozzle means formed on a second surface opposite to the first surface, and having a discharge port for discharging ink contained in the ink cavity. The present invention provides an ink jet recording head in which the substrate is exposed at the outer peripheral portion of the surface.

Further, a step can be formed on the outer peripheral portion of the chip. With such a structure, the exposed portion or the step portion of the substrate can be engaged with a predetermined position of the base to which the substrate is fitted, and the substrate can be easily fitted to the base.

Further, the present invention provides an ink jet recording line head in which a plurality of chips constituting the ink jet recording head are arranged. By doing so, high resolution is achieved, and it is possible to easily cope with high-speed printing.

Further, according to the present invention, there is provided a piezoelectric element comprising a lower electrode, a piezoelectric film and an upper electrode formed on a first surface of a substrate, and formed at a position corresponding to the piezoelectric element on the substrate. An ink cavity, and nozzle means formed on a second surface of the substrate opposite to the first surface and having a discharge port for discharging ink contained in the ink cavity;
A method for manufacturing an ink jet recording head comprising: a substrate having a lower electrode forming film on a first surface thereof, and an intermediate film having a thermal expansion characteristic comparable to that of the lower electrode forming film on a second surface thereof. Forming a film, forming a piezoelectric film and an upper electrode on the lower electrode forming film, then patterning the lower electrode forming film to form a piezoelectric element, and forming the intermediate layer. Providing a method of manufacturing an ink jet recording head, comprising: a step of forming an ink cavity in a formed substrate; and a step of providing nozzle means through the intermediate film on the substrate in which the ink cavity is formed. It is.

In this method, after forming films having similar thermal expansion characteristics on both surfaces of the substrate, that is, these films cancel each other out of the warpage and distortion of the substrate, thereby improving the flatness of the substrate. Later, patterning for forming a piezoelectric element is performed. Therefore, uniform and highly accurate patterning can be performed.

Further, according to the present invention, there is provided a piezoelectric element comprising a lower electrode, a piezoelectric film and an upper electrode formed on a first surface of a substrate, and formed at a position corresponding to the piezoelectric element on the substrate. An ink-jet recording method comprising: an ink cavity; and nozzle means formed on a second surface of the substrate opposite to the first surface and having an ejection port for ejecting ink contained in the ink cavity. A method of forming a film for forming a lower electrode, a film for forming a piezoelectric film, and a film for forming an upper electrode on a substrate in order, wherein the film for forming an upper electrode and the film for forming a piezoelectric film are provided. And a step of dividing the film for forming the lower electrode into chip units, and patterning the film for forming the upper electrode, the film for forming the piezoelectric film, and the film for forming the lower electrode divided into the chip units to form the piezoelectric element And an inkjet process comprising: There is provided a manufacturing method of the recording head.

In the present invention, “chip” means
A unit in which a plurality of piezoelectric elements and ink cavities are formed and function as an ink jet recording head.

According to this method, the film for forming the upper electrode, the film for forming the piezoelectric film, and the film for forming the lower electrode are divided into chips to reduce the warpage and distortion generated on the substrate. Is performed to form a pattern. Therefore, uniform and highly accurate patterning can be performed.

Further, the present invention provides a method for forming a film for canceling or balancing stress on the piezoelectric element side of an ink jet recording head based on the fact that the warpage or distortion of the substrate is largely due to the residual stress of the piezoelectric element. Features. Since the warpage and distortion of the substrate largely depend on the tensile stress due to the lower electrode of the piezoelectric element, particularly platinum, the ink jet recording head of the present invention is particularly suitable for a film having a compressive stress on the piezoelectric element side of the substrate. Is formed to offset the tensile stress.

One embodiment of the present invention is characterized in that a metal oxide film having a compressive stress corresponding to the tensile stress of the piezoelectric element is provided on the side of the piezoelectric element of the ink jet recording head. Things.

Another embodiment of the present invention is characterized in that the tensile stress and the compressive stress are balanced to such an extent that the substrate is not warped or distorted.

According to still another embodiment of the present invention, in the ink jet recording head, a film having a compressive stress is formed on the piezoelectric element side so as to exert a compressive stress as a whole, and also on the ink discharge side. A film exhibiting a compressive stress is formed to generate a compressive stress having a value balanced on both surfaces of the substrate, that is, a compressive stress that does not cause the substrate to be warped or distorted. This configuration is achieved by forming the thickness of the metal oxide film on the piezoelectric element side to be larger than the thickness of the metal oxide film on the ink cavity side. In a typical example, the former film thickness is almost twice as large as the latter film thickness.

The balance of the compressive force on both sides of the substrate can be achieved by forming metal oxide films on the piezoelectric element side and the ink cavity side, respectively, and appropriately adjusting the thickness and material of both. When the same metal oxide film is formed on both sides of the substrate, as described above, the thickness of the metal oxide on the side where the lower electrode having tensile stress is formed is the same as that of the metal oxide on the ink cavity side. It becomes larger than the film thickness.

The preferred range (ratio) of the film thickness is as follows.

Lower electrode: 0.3-0.9 PZT: 0.5-3.0 Upper electrode: 0.05-0.2 Silicon oxide film (lower electrode side): 1.0-2.0 Silicon oxide Film (ink cavity side): 0.5-1.
5 (The unit is μm.) The oxide film is preferably a silicon oxide film (silicon dioxide). In particular, a silicon oxide film formed by a thermal oxidation method is effective because it becomes a dense crystal.
In addition, zirconium dioxide, tantalum oxide, and iridium oxide may be used. Further, it is possible to provide zirconium dioxide or the like on the piezoelectric element side and stack it on the silicon oxide film to adjust the compressive stress appropriately.

In a more specific embodiment of the present invention, the first substrate
A piezoelectric element formed on the surface of the substrate, an ink cavity formed at a position corresponding to the piezoelectric element on the substrate,
A nozzle means formed on a second surface of the substrate opposite to the first surface, the nozzle means having a discharge port for discharging ink contained in the ink cavity. An oxide film between the piezoelectric element and the substrate, and an oxide film between the nozzle plate and the substrate,
The compression stress is formed so as to be balanced.

The ink jet recording head according to the present invention is characterized in that the compressive stress on the piezoelectric element side and the compressive stress on the ink ejection side are balanced to such an extent that no warping or distortion occurs in the substrate. Therefore, the patterning of the element can be performed with high precision.

In the present invention, the nozzle means
For example, it is realized by a member forming an ink ejection port.

[0040]

Next, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing an example of an ink jet recording head. FIG. 1 shows a part of an ink jet recording head. The ink jet recording head includes a piezoelectric element 20 formed on a first surface of a silicon substrate 11 with a silicon oxide film 12 interposed therebetween, and an ink formed at a position corresponding to the piezoelectric element 20 on the silicon substrate 11. A cavity 18, an intermediate film 17 formed on the second surface of the silicon substrate 11 opposite to the first surface via the silicon oxide film 13, and an intermediate film 17 formed on the intermediate film 17; And a nozzle plate 26 having an ejection port 25 for ejecting the ink stored in the nozzle plate 26.

The piezoelectric element 20 has a structure in which a lower electrode 14, a PZT film 15, and an upper electrode 16 are sequentially stacked from the silicon substrate 11 side. In this embodiment, platinum was used as the lower electrode forming material and the upper electrode forming material. The intermediate film 17 was made of the same material as the lower electrode forming material, that is, platinum. This intermediate film 17
Has the same thickness as the lower electrode 14. The nozzle plate 26 was made of stainless steel.

In the ink jet recording head having this structure, the lower electrode 14 is provided on the first surface of the silicon substrate 11.
An intermediate film 1 made of the same material as the lower electrode 14 is formed on the second surface.
7, the lower electrode 14 and the silicon substrate 1
Even if the coefficient of thermal expansion is different from 1, the warpage and distortion of the silicon substrate 11 caused by this can be canceled by the intermediate film 17 and the lower electrode 14. Therefore, it is possible to form the piezoelectric element 20 having a uniform shape, and to provide a highly accurate and highly reliable ink jet recording head without re-deposition (residual residue).

Further, due to the presence of the intermediate film 17, the adhesiveness between the silicon substrate 11 having the silicon oxide film 13 formed thereon and the nozzle plate 26 can be improved.

Next, a method of manufacturing an ink jet recording head having this structure will be described with reference to FIG. First, in a step shown in FIG. 2A, a silicon oxide film 1 is formed on a first surface of a silicon substrate 11 by a thermal oxidation method.
2, a silicon oxide film 13 is formed on a second surface opposite to the first surface. Next, an intermediate film 17 made of platinum is formed on the silicon oxide film 13 by a thin film forming method such as a sputtering film forming method.

Next, in the step shown in FIG. 2B, the lower electrode forming film 1 made of platinum is formed on the silicon oxide film 12.
4A is formed. The lower electrode forming film 14A was formed with the same thickness as the intermediate film 17. By this step, a platinum film is formed on both surfaces of the silicon substrate 11, so that even if the platinum and the silicon substrate have different coefficients of thermal expansion, the silicon substrate 11 is prevented from being warped or distorted. be able to.

Next, a PZT film 15A is formed on the lower electrode forming film 14A by a film forming method such as a sol-gel method, a high-frequency sputtering film forming method, and a CVD method. Thereafter, heat treatment is performed on the silicon substrate 11 on which these films are formed.

Next, in the step shown in FIG.
An upper electrode forming film 16A is formed on the T film 15A by a thin film forming method such as a sputtering film forming method. Next, FIG.
In the step (4), a photoresist film 21 is formed in the upper electrode formation region on the upper electrode formation film 16A.

On the other hand, a photoresist pattern 22 is formed in a region other than the ink cavity forming region on the intermediate film 17. Note that the photoresist 21 is used to prevent the once-etched material from being deposited again when the lower electrode forming film 14A is patterned in a later step.
The shape was such that a taper extending toward the silicon substrate side was provided on the side surface.

Next, in the step shown in FIG. 2 (5), using the photoresist 21 as a mask, the upper electrode forming film 16A is formed.
The upper electrode 16 and the PZT film 15 are formed by etching the PZT film 15A. Then, photoresist 2
Remove one.

The photolithography (patterning) step performed in FIGS. 2 (4) and (5)
1 can be performed without warping or distortion. Therefore, the photoresists 21 and 22 can be formed in a uniform shape with good reproducibility in the wafer surface, and good etching can be performed while preventing redeposition.

Next, in the step shown in FIG. 2 (6), the lower electrode forming film 1 on which the upper electrode 16 and the PZT film 15 are formed is formed.
A photoresist 23 having a uniform shape is formed in the lower electrode formation region on 4A in the same manner as described above.

Next, in the step shown in FIG. 2 (7), the lower electrode forming film 14A is etched using the photoresist 23 as a mask to form the lower electrode 14. In this way,
A piezoelectric element 20 including a lower electrode 14, a PZT film 15, and an upper electrode 16 was formed on a silicon substrate 11 with a silicon oxide film 12 interposed therebetween.

Next, in the step shown in FIG. 2 (8), the intermediate film 17 is etched using the photoresist 22 as a mask. Next, in the step shown in FIG.
The silicon oxide film 13 and the silicon substrate 11 are etched by using the intermediate film 17 patterned in the process shown in FIG.

Thereafter, the nozzle plate 26 is interposed through the intermediate film 17.
And the like, to perform a desired process to complete the ink jet recording head. Here, platinum was used as the material for forming the lower electrode and the material for forming the intermediate film. However, the material is not limited to this, and iridium, a platinum iridium alloy, a platinum palladium alloy, or the like may be used.

The case where the lower electrode 14 and the intermediate film 17 are made of the same material has been described. However, the present invention is not limited to this. The intermediate film 17 has a thermal expansion coefficient similar to that of the lower electrode forming material. If it is a material which is different from the material for forming the lower electrode, the material may be different.

(Embodiment 2) Next, Embodiment 2 according to the present invention will be described with reference to the drawings. In the present embodiment, the same members as those of the ink jet recording head described in the first embodiment are denoted by the same reference numerals, and detailed description thereof may be omitted.

FIG. 3 is a cross-sectional view showing a part of the ink jet recording head according to the second embodiment, FIG. 4 is a cross sectional view showing a manufacturing process of the ink jet recording head shown in FIG. 3, and FIG. FIG. 7 is an exploded view of the ink jet recording head according to Embodiment 2.

The ink jet recording head shown in FIG. 3 has a silicon oxide film 1 on a first surface of a silicon substrate 11.
2, an ink cavity 18 formed at a position corresponding to the piezoelectric element 20 on the silicon substrate 11, and a second surface opposite to the first surface of the silicon substrate 11. A nozzle plate 26 formed through the silicon oxide film 13 and having an opening 25 for discharging ink contained in the ink cavity 18;
It is provided with.

The outer peripheral portion of the chip on the first surface of the silicon substrate 11 is exposed without being covered by the silicon oxide film 12, and a step 19 is formed in this portion. As shown in FIG. 5, after the nozzle plate 26 is adhered to the silicon substrate 11 on which the above-described elements are formed, and the step portion 19 is fitted to the base 90, as shown in FIG. Engages. The silicon substrate 11 is simply and reliably fixed to the base 90 by the step 19. Reference numeral 98 denotes a wiring board for providing a signal to the piezoelectric element 20.

Next, a method of manufacturing an ink jet recording head having this structure will be described with reference to FIG. First, in the step shown in FIG. 4A, the silicon oxide film 12 is formed on the first surface and the silicon oxide film 13 is formed on the second surface of the wafer-shaped silicon substrate 11 in the same manner as in the first embodiment. Formed, and further on the silicon oxide film 12,
The lower electrode forming film 14A and the PZT film 15A are formed.

Next, in the step shown in FIG.
An upper electrode forming film 16A is formed on the PZT film 15A obtained in the step shown in (1). Next, in a step shown in FIG. 4C, a photoresist 41 for dividing the silicon substrate 11 on which the above-described film is formed into chip units is formed on the upper electrode forming film 16A.

Next, in the step shown in FIG. 4D, using the photoresist 41 as a mask, the upper electrode forming film 16 is formed.
A, the PZT film 15A and the lower electrode forming film 14A are etched and divided into chip units. In this manner, the lower electrode forming films 14B, P
The ZT film 15B and the upper electrode forming film 16B are obtained.

In this step, the lower electrode forming film 14A that causes the silicon substrate 11 to warp or warp is divided into chips, so that the silicon substrate 11 can be prevented from warping or warping. In addition, the photolithography process performed at the time of division into chips does not require a higher precision than the above-described patterning, so that even if the silicon substrate 11 has some warpage or distortion, it does not particularly cause a problem. .

FIG. 4 (5) is an enlarged sectional view of one chip obtained in the step shown in FIG. 4 (4). In the step shown in FIG. 4 (6), a photoresist 42 is formed in the upper electrode formation region on the upper electrode formation film 16B.

On the other hand, in a region other than the ink cavity forming region on the silicon oxide film 13, a photoresist 43 is formed. Note that the photoresist 42 is used to prevent the once-etched material from re-depositing during patterning of the lower electrode forming film 14B in a later step.
The shape was such that a taper extending toward the silicon substrate side was provided on the side surface.

Next, in the step shown in FIG. 4 (7), the upper electrode forming film 16B is formed using the photoresist 42 as a mask.
Then, the PZT film 15B is etched by ion milling to form a pattern of the upper electrode 16 and the PZT film 15. At this time, the silicon oxide film 12 exposed on the outer peripheral portion of the chip is simultaneously etched, and the silicon substrate 11 thereunder is also etched.
1 is exposed, and a step 19 is formed.

Thereafter, the photoresist 42 is removed.
Thus, the lower electrode 14, the PZT film 15, and the upper electrode 1 are formed on the silicon substrate 11 with the silicon oxide film 12 interposed therebetween.
6 were formed.

The photolithography step performed in this step can be performed in a state where the silicon substrate 11 has no warpage or distortion due to division into chips. Therefore, the photoresists 42 and 43 can be formed in a uniform shape with good reproducibility, and good etching can be performed while preventing redeposition.

Next, in the step shown in FIG. 4 (8), after the silicon oxide film 13 is patterned using the photoresist 43 as a mask, the silicon substrate 11 is etched using the patterned silicon oxide film 13 as a mask to form an ink cavity. 18 are formed.

Thereafter, a desired process such as providing a nozzle plate 26 at a predetermined position is performed to complete an ink jet recording head. In the first and second embodiments, the case where a PZT-based material is used as the piezoelectric film has been described.
A material obtained by adding another metal oxide such as niobate, nickel oxide, or magnesium oxide to this system, or a material other than the PZT system may be used.

FIG. 9 shows an example of a nozzle unit in place of the nozzle plate 26 for the substrate 11 (a pressure chamber substrate forming the ink chamber 18 serving as a pressure chamber) in FIG. More specifically, FIG. 9 shows a layer structure of the pressure chamber substrate 100 and the nozzle unit. Here, a type in which the common flow path of the ink is formed not on the pressurized chamber substrate but on the reservoir chamber forming substrate is shown.

The nozzle unit 2 includes a communication path substrate 260 having a communication path 270 formed therein, an ink supply path forming substrate 240 having a plurality of ink supply holes 250, a reservoir chamber forming substrate 220 having an ink reservoir chamber 230, and a plurality of It is constituted by a nozzle forming substrate 200 having a nozzle 210. The pressure chamber substrate 100 and the nozzle unit 2 are joined by an adhesive. The ink reservoir chamber 230 has the same function as the common flow channel 112 in FIG.

FIG. 2 shows a structural diagram in which four nozzles are arranged in four rows and two rows are arranged vertically for simplification.
The number of nozzles and the number of rows are not limited, and any combination may be used. 5, a pressure chamber (ink cavity) is provided in the substrate 11 in a plurality of strips, and a common flow channel 112 for supplying ink to all the pressure chambers is provided. Each ink cavity is separated by a side wall 18A.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to the drawings. In the third embodiment, a line head in which the chips obtained in the second embodiment are arranged on a plurality of lines will be described. Since this chip has the same structure as that obtained in the second embodiment, the same reference numerals are given and the detailed description is omitted.

This line head is, as shown in FIG.
It has a structure in which four chips are arranged on a base 91. That is, it has a structure in which four ink jet recording heads shown in FIG. 5 are arranged on a line.

The ink cavities 18 of the line head respectively store black ink, cyan ink, magenta ink, and yellow ink. In this way, it corresponds to the force printing.

In the third embodiment, the case where the chip obtained in the second embodiment is used has been described. However, the present invention is not limited to this. It goes without saying that a chip having another structure may be used as long as it is a chip constituting the head. Also, the number of chips to be installed is not limited to four, but can be set arbitrarily.

(Embodiment 4) FIG. 7 is a sectional view of an ink jet recording head provided with a film having a compressive stress for relaxing, eliminating or compensating for a tensile stress generated by a lower electrode of a piezoelectric element. is there. In this embodiment,
It is manufactured by the steps almost described in FIG. In this embodiment, the same components as those in the embodiment of FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

This ink jet type recording head is shown in FIG.
Similarly, the silicon oxide films 12 and 13 are formed on the piezoelectric element 20 side and the ink cavity 18 side of the substrate 11, respectively.
It has. The nozzle plate 26 and the silicon oxide film 1
3, the intermediate film 17 is omitted.

The piezoelectric element 20 composed of the upper electrode 16, the PZT film 15, and the lower electrode film 14 has a tensile stress as a whole. Each of these films has a tendency to have a tensile stress, and is close to the high temperature annealing during the heat treatment of PZT because the lower electrode has a large shrinkage ratio and the upper electrode is not formed during the annealing. The effect of the tensile stress of the lower electrode greatly affects the flatness of the substrate.

On the other hand, the silicon oxide film 12 between the lower electrode 14 and the silicon substrate 11 and the silicon oxide film 13 between the substrate, the silicon substrate 11 and the nozzle plate 26
Has a compressive stress. The following relationship is set when the relationship between the stresses of these films is shown.

A + B = C A: Tensile stress of piezoelectric element (+) B: Compressive stress of silicon oxide film 12 (-) C: Compressive stress of silicon oxide film 13 (-) Since the tensile stress on the piezoelectric element side is canceled by the compressive stress of the silicon oxide film 12 and the compressive stress on the piezoelectric element side and the ink cavity side of the silicon wafer are balanced, the PZ
Even after the heat treatment of T, the wafer does not warp, and the patterning after (5) in FIG. 2 can be performed with high accuracy.

The silicon oxide film is formed by a thermal oxidation method as in FIG. The relationship between the stresses is realized by appropriately adjusting the thickness of the silicon oxide film. On the piezoelectric element side of the substrate, the compressive stress is generated by overcoming the tensile stress of the piezoelectric element, and since the compressive stress on the piezoelectric element side of the substrate and the ink cavity side are balanced, the piezoelectric element side The thickness of the silicon oxide film 12 is larger than the thickness of the silicon oxide film 13 on the ink cavity side, and the silicon oxide film on the piezoelectric element side generates a larger value of compressive stress. Is formed.

The thickness of these silicon oxide films is appropriately determined in consideration of the thickness of the piezoelectric element and the like.

FIG. 8 is a diagram corresponding to (3) in FIG. 2. In this embodiment, the silicon oxide film 12 on the piezoelectric element side has a value almost twice that of the silicon oxide film 13 on the ink cavity side. It is formed with a film thickness. The silicon oxide films 12 and 13 are formed by different processes, respectively.
By making the thermal oxidation time for forming the silicon oxide film of the reference numeral 12 longer than that of the silicon oxide film of the reference numeral 13, the silicon oxide film of the reference numeral 12 can be formed thicker than that of the reference numeral 13. In FIG. 8, since a balanced compressive stress is formed on the upper and lower surfaces of the silicon substrate, physical deformation such as warpage, distortion, or twisting of the substrate is unlikely to occur.

If the silicon oxide film 12 on the side of the piezoelectric element is substantially balanced with the tensile stress of the piezoelectric element,
The silicon oxide film 13 on the ink cavity side may be omitted. Further, instead of or in addition to the silicon oxide film, another metal oxide film such as ZrO ₂ , Ta
₂ O ₅ and IrO _x are formed on the silicon oxide film 12,
The compression stress may be adjusted.

Incidentally, as in the embodiment shown in FIG.
Of the substrate 11, dividing the chip for each chip as in the embodiment of FIG. 4, and forming a stress relaxation film as shown in FIG. And other physical deformations can be effectively prevented or mitigated to achieve high-precision patterning. As a result, it is possible to obtain an ink jet recording head in which leakage and short circuit between electrodes are prevented.

The ink discharge means and the nozzle means are not particularly limited, such as those using a nozzle plate or those comprising a nozzle unit as shown in FIG.

[0090]

As described above, according to the present invention, a photolithography process for forming a piezoelectric element can be performed on a flat substrate. As a result, it is possible to perform element patterning with high accuracy, to prevent the occurrence of a leak or a short circuit between electrodes, and to provide a highly reliable ink jet recording head.

Further, it is easy to fit the chip on which the desired element is formed on the base, and it is also possible to improve the adhesiveness between the substrate on which the ink cavity is formed and the nozzle plate.

Further, if a plurality of chips according to the present invention are arranged side by side, they can be used as a line head. As a result, high resolution is achieved, and color printing can be easily supported.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of an ink jet recording head according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the ink jet recording head shown in FIG.

FIG. 3 is a cross-sectional view showing a part of an ink jet recording head according to Embodiment 2 of the present invention.

FIG. 4 is a cross-sectional view showing a manufacturing process of the ink jet recording head shown in FIG.

FIG. 5 is an exploded view of an ink jet recording head according to Embodiment 2 of the present invention.

FIG. 6 is a plan view of an ink jet recording line head according to Embodiment 3 of the present invention.

FIG. 7 is a sectional view of an ink jet recording line head according to Embodiment 4 of the present invention.

FIG. 8 is a cross-sectional view showing one of the steps in the middle.

FIG. 9 is an exploded perspective view of the nozzle unit.

[Explanation of symbols]

 Reference Signs List 11 silicon substrate 12, 13 silicon oxide film 14 lower electrode 15 PZT film 16 upper electrode 17 intermediate film 18 ink cavity 19 stepped portion 20 piezoelectric element

Claims (18)

[Claims] 1. A substrate having an individual ink passage formed therein, a piezoelectric element formed in each portion corresponding to the individual ink passage, and an ink ejection means for ejecting ink in the individual ink passage. An ink jet recording head according to claim 1, wherein an intermediate film having a thermal expansion characteristic substantially equal to that of a lower electrode forming said piezoelectric element is provided on said ink discharging means side. 2. A piezoelectric element formed on a first surface of a substrate, an ink cavity formed on the substrate at a position corresponding to the piezoelectric element, and a piezoelectric element on a side opposite to the first surface of the substrate. A nozzle means formed on the second surface and having a discharge port for discharging ink contained in the ink cavity;
An ink jet recording head comprising: an intermediate film having a thermal expansion characteristic similar to that of a lower electrode constituting the piezoelectric element between a second surface of the substrate and nozzle means. Inkjet recording head. 3. The ink jet recording head according to claim 1, wherein the intermediate film is made of a lower electrode forming material. 4. The ink jet recording head according to claim 1, wherein the thickness of the lower electrode is equal to the thickness of the intermediate film. 5. A piezoelectric element formed on a first surface of a substrate, an ink cavity formed on the substrate at a position corresponding to the piezoelectric element, and a piezoelectric element on a side opposite to the first surface of the substrate. A nozzle means formed on the second surface and having a discharge port for discharging ink contained in the ink cavity;
An ink jet recording head comprising: a substrate exposed at a chip outer peripheral portion of a first surface of the substrate. 6. The ink jet recording head according to claim 5, wherein a step is formed on the outer peripheral portion. 7. An ink jet recording line head comprising a plurality of chips constituting the ink jet recording head according to claim 1 arranged side by side. 8. A piezoelectric element comprising a lower electrode, a piezoelectric film, and an upper electrode formed on a first surface of a substrate, an ink cavity formed at a position on the substrate corresponding to the piezoelectric element, Production of an ink jet recording head, comprising: nozzle means formed on a second surface of the substrate opposite to the first surface and having an ejection port for ejecting ink contained in the ink cavity. Forming a film for forming a lower electrode on a first surface of a substrate and forming an intermediate film having a thermal expansion coefficient similar to that of the film for forming a lower electrode on a second surface of the substrate; Forming a piezoelectric film and an upper electrode on the forming film, and then patterning the lower electrode forming film to form a piezoelectric element; and forming an ink cavity in the substrate on which the intermediate layer is formed. And the ink cavity is formed Providing a nozzle means on the substrate with the intermediate film interposed therebetween. 9. The method according to claim 8, wherein the intermediate film comprises a lower electrode forming material. 10. The ink jet recording head according to claim 8, wherein the intermediate film is formed to have a thickness equal to that of the lower electrode forming film. 11. A lower electrode formed on a first surface of a substrate,
A piezoelectric element composed of a piezoelectric film and an upper electrode; an ink cavity formed on the substrate at a position corresponding to the piezoelectric element; and a second surface opposite to the first surface of the substrate formed on the second surface. A nozzle means having an ejection port for ejecting the ink contained in the ink cavity, comprising: a lower electrode forming film, a piezoelectric film forming on a substrate; Forming a film for forming an upper electrode and a film for forming an upper electrode in order, dividing the film for forming an upper electrode, the film for forming a piezoelectric film and the film for forming a lower electrode into chips, and dividing the film into chips. Film for forming the upper electrode,
Forming a piezoelectric element by patterning the film for forming a piezoelectric film and the film for forming a lower electrode to form a piezoelectric element. 12. An ejecting recording head in which a film for canceling the stress of the piezoelectric element is formed on the piezoelectric element side of the substrate. 13. The ink jet recording head according to claim 12, wherein the film for canceling the stress has a compressive stress balanced with the tensile stress of the piezoelectric element. 14. The ink jet recording head according to claim 13, wherein the film having a compressive stress is made of a metal oxide. 15. The ink jet recording head according to claim 12, wherein the tensile stress and the compressive stress are balanced to such an extent that the substrate does not warp or warp. 16. The ink jet recording head according to claim 12, wherein a film having a compressive stress is formed on the piezoelectric element side of the substrate so as to exert a compressive stress as a whole, and also on the ink discharge side of the substrate. An ink jet recording head, wherein a film exhibiting a compressive stress is formed to generate a balanced compressive stress on both surfaces of the substrate. 17. A film having a compressive stress is made of a metal oxide, and the thickness of the metal oxide film on the piezoelectric element side is formed to be larger than the thickness of the metal oxide film on the ink ejection side. An ink jet recording head according to claim 16. 18. A piezoelectric element formed on a first surface of a substrate, an ink cavity formed on the substrate at a position corresponding to the piezoelectric element, and a piezoelectric element on a side opposite to the first surface of the substrate. A nozzle means formed on a second surface and having an ejection port for ejecting the ink contained in the ink cavity; and an ink jet recording head comprising: a space between the piezoelectric element and a substrate. And an oxide film between the nozzle means and the substrate is formed such that the compressive stress is balanced.