JP2002370354A - Liquid jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jet head in which liquid jet characteristics are enhanced by realizing a lower electrode having a low protrusion density on the surface and a high voltage PZT film. SOLUTION: The liquid jet head comprises nozzles for jetting ink drops, liquid chambers formed in a substrate to communicate with the nozzles, a diaphragm constituting a part of the liquid chamber, and a piezoelectric element comprising a lower electrode, a piezoelectric film and an upper electrode formed on the diaphragm wherein the lower electrode is formed of platinum or an alloy containing platinum on the diaphragm through an adhesion film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid jet head suitably used for a liquid jet recording apparatus.

In general, a liquid jet recording apparatus includes a liquid chamber, a nozzle, a liquid jet head having a liquid flow path, and an ink supply system, and applies energy to ink filled in the liquid chamber to thereby provide energy to the liquid chamber. Ink is extruded into the liquid flow path, and as a result, ink droplets are ejected from the nozzle,
Thereby, the recording of the character / image information is performed.

As means for applying energy to ink, means for applying pressure to the liquid chamber using a piezoelectric element or means for heating ink in the liquid chamber using a heater are widely used.

The present invention particularly relates to a liquid ejecting head having means for pressurizing a liquid chamber using a piezoelectric element.

[0005]

2. Description of the Related Art As a prior art of the liquid ejecting head as described above and the components related to the present invention, Japanese Patent Publication No.
No. 22790, JP-A-2-219654, U.S. Pat.
No. 312008, Torii et al. (Japanese Journal of Applied Physics, Vo 1.30, No. 12)
B, December 1991, 3562-3566),
Japanese Patent Publication No. 4-43535 and Japanese Patent Application Laid-Open No. 3-124450 disclose such a technique.

In Japanese Patent Publication No. 62-22790, an electrode is formed on a substrate having a thinner portion corresponding to the liquid chamber, and PZT is formed at the position corresponding to the liquid chamber by a thin film forming method such as sputtering or printing. A method for manufacturing a liquid ejecting head for forming a thin film is disclosed.

In Japanese Patent Application Laid-Open No. 2-219654, a diaphragm and a diaphragm are formed on a thin plate laminated on a semiconductor substrate provided with a nozzle, in which a liquid chamber and a liquid flow path are formed. A liquid ejecting head including a piezoelectric vibrator provided on an upper part, and a nozzle formed on a semiconductor substrate, a dry film is adhered on the semiconductor substrate, and a vibrating plate, a lower electrode, a piezoelectric film, There is disclosed a method of manufacturing a liquid jet head which is formed by stacking electrodes and removing the dry film.

In US Pat. No. 4,311,2008, a liquid ejecting head comprising a liquid passage formed on the surface of a substrate and a liquid chamber penetrating the substrate, wherein the substrate is joined to both surfaces of the substrate, and a piezoelectric body is provided. Is disclosed.

[0009] Torii et al. (Japanese Journal of Applied Physics, Vo 1.30, No. 12B, 1
(December 991, p. 3562-3566) discloses the use of platinum for the lower electrode of a PZT thin film.

Japanese Patent Publication No. 4-43535 discloses a method for forming a base metal thin film and a platinum film on an insulating thin film, and performing a heat treatment at a temperature at which the surface of the platinum film becomes uneven due to crystal grain growth. Is disclosed.

In Japanese Patent Application Laid-Open No. 3-124450, a nozzle is formed from one surface of a single-crystal silicon substrate, and p-type single-crystal silicon is formed on another surface of the single-crystal silicon substrate. There is disclosed a method of manufacturing a liquid jet head in which a p-type silicon layer and a single crystal silicon substrate are epitaxially grown, and a p-type silicon layer and a single crystal silicon substrate are thereafter etched to form a liquid chamber and a cantilevered, double-sided vibration plate.

However, the above-described conventional liquid jet head, its components, and their manufacturing methods have the following problems to be solved.

In Japanese Patent Publication No. 62-22790, although the thickness of the component is not set in the claim, the PZT thickness tp and the diaphragm thickness tv in the embodiment are set to 50 μm and 50 to 50 μm, respectively.
It is set to about 100 μm, and tp + tv is 10 μm.
It is clear that the region of about m or less is not considered. If tp + tv is about 100 μm, it is still too thick, so that the amount of deformation of the diaphragm when a voltage is applied to PZT is small. As described above, a circular liquid chamber having a size of about 2 mm in diameter is required. At this time, in order to improve the resolution, as shown in the embodiment, the plane configuration is such that the liquid chamber pitch> the nozzle pitch, and the area efficiency is low. That is, the plane size of the liquid ejecting head having seven nozzles is 20 mm × 15.
mm. In order to further increase the number of nozzles, not only does the plane size dramatically increase, but also the liquid flow path connecting the liquid chamber and the nozzle becomes longer, the flow resistance increases, and the speed of the liquid ejection operation becomes extremely high. descend.

Further, in the conventional example, a thin diaphragm is formed at a position corresponding to the liquid chamber, and PZT is formed thereon. According to experiments by the present inventors, the liquid chamber,
In a method of forming PZT after forming a diaphragm,
When tp + tv is further reduced, for example, tp is set to 3 μm.
When m and tv were set to 1 μm, phenomena such as sagging, wrinkling, and destruction of the diaphragm occurred during the manufacturing process, and the manufacturing yield of the liquid jet head was extremely reduced.

In Japanese Patent Application Laid-Open No. 2-219654, the nozzles are formed by processing Si substrates of both positions (100). For example, a thickness of about 300 μm (10
0) When forming a nozzle by anisotropically etching a Si substrate, even if the nozzle size is 30 μm square, an opening in the substrate surface on the opposite side is inevitable even if the nozzle size is 30 μm square due to the angular relationship with the (111) plane having a low etching rate. It is about 400 μm square. For this reason, the nozzle pitch is not less than 400 μm, and the resolution is at most about 60 dpi (dot per inch). That is, it is impossible to increase the nozzle density of the liquid jet head.

Further, in the embodiment of the prior art, both the piezoelectric film and the upper and lower electrodes are formed larger than the liquid chamber, and in such a configuration, when a voltage is applied to the piezoelectric film, vibration is efficiently generated. It is impossible to deform the plate and eject the liquid. Further, there is no mention of the size relationship and the thickness relationship of the piezoelectric film, the upper and lower electrodes, and the liquid chamber for efficiently ejecting the liquid.

Further, in the embodiment of the conventional example, a single layer of SiO ₂ is used for the diaphragm. Sio ₂ has a Young's modulus as small as 10 ¹⁰ N / m ² , and when a piezoelectric thin film is formed thereon and a voltage is applied to deform the piezoelectric thin film in a horizontal direction, the piezoelectric thin film simultaneously expands greatly in a horizontal direction, and is vertically elongated. The deformation in the direction is not so large. That is, Si
Even when the o ₂ single layer is used, it is impossible to efficiently deform the diaphragm and apply the liquid when a voltage is applied to the piezoelectric film. Further, there is no mention of diaphragm characteristics or materials for efficiently ejecting liquid.

US Pat. No. 4,311,2008 describes in its claim that a piezoelectric crystal is mounted on a diaphragm. Further, even in the embodiment, there is a description of mounting with an indium-based solder, and it is clear that the present invention is directed to a piezoelectric body having a thickness larger than that described in JP-B-62-2790. Therefore, nozzle density cannot be substantially increased as in the above-mentioned Japanese Patent Publication No. 62-22790. In the case of US Pat. No. 4,311,2008, when a liquid flow path is formed by using anisotropic etching, the flow path shape is determined by both positions of the Si substrate. Met. For example, when (100) Si is used, the cross-sectional shape of the liquid channel is an inverted triangle, while when (110) Si is used, it is a rectangle. If the liquid flow path is an inverted triangle, air bubbles are likely to accumulate, causing trouble. Also, (11
0) When a rectangular liquid flow path is formed in Si, it is difficult to control the depth of the liquid flow path, and the resulting depth is not uniform.

Furthermore, undercut etching inevitably occurs at the contact point between the liquid flow path and the liquid chamber, so that the contact shape varies and the liquid ejection characteristics are not constant. In addition, in the conventional example, two substrates for sealing the Si substrate are required, and two bonding steps are required, so that the manufacturing process is complicated and the manufacturing cost is disadvantageous.

Torii et al. (Japanese Journal of Applied Physics, Vo 1.30, No. 12B, 1
(December 991, p. 3562-3566), a platinum film is formed directly on Sio ₂ as a lower electrode of a PZT film. However, it is a well-known fact that such a configuration has a problem in the adhesion between silicon oxide and platinum. Peeling occurred between silicon oxide and platinum during a later operation. Further, in order to solve the above problems and to improve the adhesion between the insulating material such as silicon oxide and platinum and platinum, as shown in Japanese Patent Publication No. 43435/1973, titanium is inserted between the platinum and the insulating material. Although it is known that the PZT film is formed, projections are formed on the surface of the platinum during the formation of the PZT film or during the subsequent heat treatment, and this reduces the withstand voltage of the PZT film.

In Japanese Patent Application Laid-Open No. 3-124450, anisotropic etching of a single-crystal silicon substrate is performed such that an etchant automatically flows around the surface on the piezoelectric element side. A phenomenon in which a piezoelectric element is side-etched by an aqueous etchant, for example, an aqueous solution of potassium hydroxide occurs, and this reduces the yield of the liquid ejecting head.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has the following objects.

(1) To provide a liquid ejecting head capable of performing an efficient liquid ejecting operation, having a small size in plan view even if the number of nozzles is increased, and having a high density of nozzles.

(2) To provide a liquid ejecting head which realizes a lower electrode having a small surface projection density, realizes a PZT film having a high withstand voltage, and improves liquid ejecting characteristics.

(3) A liquid jet that makes it easy to control the shape and depth of the liquid chamber and the liquid flow path, has no bubble accumulation and fluctuations in the liquid jet characteristics, and can further improve the degree of freedom in its design. Providing a head.

[0026]

According to the present invention, there is provided a liquid ejecting head comprising: a nozzle for discharging ink droplets; a liquid chamber formed on a substrate and communicating with the nozzle; and a diaphragm constituting a part of the liquid chamber. A lower electrode formed on the diaphragm, a piezoelectric film, and a piezoelectric element comprising an upper electrode;
The lower electrode is laminated on the diaphragm via an adhesive film, and the lower electrode is made of platinum or an alloy containing platinum. As a result, the adhesion between the platinum of the electrode material and the diaphragm can be increased.

It is desirable that the adhesion film is made of titanium having a thickness of 80 ° or less. Thereby, the withstand voltage of the PZT film can be improved.

The Young's modulus of the diaphragm is 1 × 10 ¹¹ N /
is configured such that m ² or more. This allows
The amount of deformation of the diaphragm increases, and a liquid ejecting operation with a sufficient margin can be performed. Particularly, the Young's modulus of the diaphragm is 2 × 10 ¹¹ N / m
If it is ² or more, the amount of deformation of the diaphragm is significantly increased, the length W of the liquid chamber in the depth direction can be reduced, and the size and speed of the liquid ejecting head can be reduced.

Suitable materials for the diaphragm include silicon nitride, titanium nitride, aluminum nitride, boron nitride, tantalum nitride, tungsten nitride, zirconium nitride, zirconium oxide, titanium oxide, aluminum oxide, silicon carbide, titanium carbide, and tungsten carbide. And a material mainly containing at least one of tantalum carbide.

The diaphragm has a Young's modulus of 1 × 10 ¹¹ N.
/ M ² or more, preferably 2 × 10 ¹¹ N / m ² or more, and a silicon oxide layer, and the silicon oxide layer is desirably arranged on the lower electrode side. As a result, the adhesion to the lower electrode or the substrate is strengthened, and the production yield can be improved.

Further, a material layer containing at least one of aluminum oxide, zirconium oxide, tin oxide, zinc oxide and titanium oxide as a main component may be inserted between the diaphragm and the lower electrode. Thereby, the piezoelectric characteristics of the PZT film can be improved.

Further, materials suitable for the piezoelectric film include:
And lead zirconate titanate.

The above-described liquid jet head is provided in a liquid jet recording apparatus.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a perspective view of a liquid jet head according to an embodiment of the present invention.

In the figure, a diaphragm 103 formed on a liquid chamber 102, a first substrate 101 on which a piezoelectric element composed of a lower electrode 104, a piezoelectric film 105 and an upper electrode 106 are formed, and a liquid flow path Second substrate 10 with 108 formed
7 are joined. Reference numeral 109 denotes a nozzle formed at an opening in a cross section where the first substrate 101 and the second substrate 107 are joined. Here, a plurality of liquid chambers 102 and nozzles 109 are arranged at the same pitch.

The operation of the liquid ejecting head will be briefly described. A voltage is applied between the lower electrode 104 and the upper electrode 106, and a piezoelectric element including the lower electrode 104, the piezoelectric film 105, the upper electrode 106, and the vibration plate 103. And the liquid chamber 102
Is reduced, the ink filling the liquid chamber 102 is pushed out to the liquid flow path 108, and the ink is ejected from the nozzle 109.

Hereinafter, the liquid jet head of the present invention and the method of manufacturing the same will be described in detail according to the manufacturing process.

FIGS. 2A, 2B, and 2C are cross-sectional views showing a manufacturing process up to forming a piezoelectric element and a liquid chamber on the first substrate 101 in the embodiment of the present invention. In addition,
In this cross-sectional view, the direction perpendicular to the paper surface is the depth direction of the liquid chamber.

The first (110) single crystal silicon is used for the first
The substrate 101 is thermally oxidized at 1200 ° C. to form a silicon oxide layer 201 on both surfaces of the substrate 101 at a thickness of 5000 °. Then, the vibration plate 103 is formed on one surface of the substrate 101. The vibration plate 103 is formed by, for example, forming silicon nitride to a thickness of 1 μm by PECVD (plasma enhanced chemical vapor deposition) and performing heat treatment at 800 ° C. in a nitrogen atmosphere. Further, the substrate 10
1. A photoresist is formed on both surfaces of the silicon oxide 201, and an opening is provided on the surface opposite to the side on which the diaphragm 103 is provided.
Is patterned with an aqueous solution of hydrofluoric acid and ammonium fluoride,
The opening 202 is formed, and a sectional view shown in FIG. At this time, the depth direction of the opening 202, that is, the direction perpendicular to the paper surface is set as the <1-12> or <-11.

Then, the lower electrode 104 is placed on the diaphragm 103.
Is formed by sputtering in a thickness of 50 ° for titanium and 2000 ° for platinum, in this order, and the patterning is performed with an aqueous solution of aqua regia. Next, PZT is formed by sputtering to a thickness of 3 μm as the piezoelectric film 105, and is patterned with an aqueous solution of hydrochloric acid. Various methods have been attempted in recent years for forming a PZT film. However, the present inventors have proposed a method of forming a substrate in an argon atmosphere by using a sintered body target in which lead oxide is excessively added to modified PZT mixed with niobium. It was formed by high-frequency sputtering without heating. After the patterning of the PZT, a heat treatment is performed at 700 ° C. in an oxygen atmosphere.
{Circle around (2)}, gold is formed to a thickness of 2000 mm in this order, and is patterned with an aqueous solution of iodine and potassium iodide.
The sectional view shown in FIG.

Thereafter, a protective film 203 is formed of photosensitive polyimide to a thickness of 2 μm, the protective film at the electrode take-out portion (not shown) is removed by development, and a heat treatment is performed at 400 ° C.
Next, the surface on the piezoelectric element side on which the protective film 203 is formed is shown in FIG.
(See below for details), and immersed in an aqueous solution of potassium hydroxide to form an opening 2 in the silicon oxide layer 201.
From 02, anisotropic etching of the single crystal silicon substrate 101 is performed to form a liquid chamber 102. At this time, the single crystal silicon substrate 10
1 are both (110) and the depth direction of the opening 202 is the <1-1 2> or <-11 12> direction, so that the side wall forming the side of the liquid chamber 102 in the depth direction is The plane can be a (111) plane. When an aqueous solution of potassium hydroxide is used, the etching rate ratio between the (110) plane and the (111) plane of single crystal silicon is about 300: 1, and a groove having a depth of 300 μm is etched by 1 μm.
m, and the liquid chamber 102 is formed. Then, while the substrate 101 is fixed to the jig, the silicon oxide in contact with the vibration plate 103 is removed by etching with an aqueous solution of hydrofluoric acid and ammonium fluoride to obtain a cross-sectional view shown in FIG.

In this embodiment, after the liquid chamber 102 is formed without the protective film 203, the heat treatment may be performed again at 700 ° C. in an oxygen atmosphere to further form the protective film. . This is a piezoelectric film (PZT film) 1
This is because the piezoelectric properties can be further improved by performing the heat treatment twice on the layer 05. Although the detailed reason for this effect is not clear, PZ constituting the piezoelectric film
It is presumed that the sintering of T proceeds to increase the crystal grain size, and as a result, the piezoelectric strain constant increases.

FIGS. 3A and 3B are views showing a jig for protecting the surface of the substrate 101 on the piezoelectric element side during anisotropic etching of the substrate 101 in the embodiment of the present invention, as described above. FIG. 5A is a configuration diagram of a jig, and FIG.
It is sectional drawing in the state which fixed 1 to the jig.

An O-ring 302 and an O-ring 302 are provided on a cylindrical fixed frame 301 having an opening on one side and having an inner wall surface threaded.
The substrate 101 and the O-ring 302 are fitted in this order, and the fixing ring 303 having a thread cut on the outer wall thereof is attached to the fixing frame 3.
It is configured to be screwed into the inner wall of the device 01 and fixed. At this time, the surface of the substrate 101 to be etched is fixed to the fixed frame 3.
01 on the opening side. In the state shown in FIG. 3B, the substrate is immersed in an etching solution such as an aqueous solution of potassium hydroxide. At this time, the substrate is sealed with the fixing ring 303, the O-ring 302, and the surface on which the substrate 101 is to be etched. Therefore, the etchant can be prevented from sneaking into the piezoelectric element side of the substrate 101. As a material of the jig, the present inventors used polypropylene.

FIG. 4 is a conceptual diagram of the mounting structure of the liquid jet head in the embodiment of the present invention.

In the figure, a first substrate 101 on which a piezoelectric element and a liquid chamber are formed, and a second substrate 101 on which a liquid flow path 108 is formed.
Nozzle 107 and liquid introduction hole 40
4 are formed. A liquid chamber 403 is formed by surrounding the liquid introduction hole 404 side with the base material 401. The liquid chamber 403 is supplied with liquid from outside (not shown). The base 401 is attached to the mounting board 402.
The second substrate 107 was formed integrally with the liquid channel 108 by injection molding of plastic.

The above is the outline of the liquid jet head of the present invention.

Next, the dimensions of the liquid chamber / electrode, the thickness of the piezoelectric film,
The relationship between the dimensions and the thickness of the diaphragm will be described. The present inventors have obtained various findings by conducting a liquid ejection experiment using the above-described liquid ejection head.

The present inventors first set the liquid chamber 102 and the lower electrode 1
04, the planar positional relationship between the piezoelectric film 105 and the upper electrode 106 by PZT was set.

First, the lower electrode 104, the piezoelectric film 105, and the upper electrode 106 were evaluated according to the above manufacturing process up to the upper electrode forming process.

When comparing the case where the upper electrode is larger than the lower electrode and the case where the lower electrode is larger than the upper electrode, the former shows that the leakage current between the upper and lower electrodes is about two digits larger than the latter. I understood. This is because P at the lower electrode end
It is considered that the leakage current of the ZT film was large.

Further, when the lower electrode is larger than the upper electrode, when the PZT film is larger than the lower electrode, and when the PZT film is smaller than the lower electrode, the former is such that the end of the PZT film is turned up from the underlying silicon nitride. In contrast, the latter could be formed without film peeling. This is PZT
It is considered that the adhesion between the film and the silicon nitride layer was insufficient. Therefore, based on the above results, the magnitude relation of upper electrode ≦ PZT film <lower electrode is satisfied, that is, the length of the upper electrode in the liquid chamber arrangement direction is Lu, and the PZT in the liquid chamber arrangement direction is Lu.
The length is Lp, and the length of the lower electrode in the liquid chamber arrangement direction is L1.
Where Lu ≦ Lp <L1 and the length of the upper electrode in the depth direction of the liquid chamber is Wu, and the PZ in the depth direction of the liquid chamber is PZ.
When the length of T is Wp and the length of the lower electrode in the depth direction of the liquid chamber is W1, there is no problem in the manufacturing process and the leakage current is suppressed by setting the magnitude relation of Wu ≦ Wp <W1. A piezoelectric element could be constructed.

Further, in order to take out the electrode from the upper electrode 106, after forming up to the liquid chamber 102 according to the above-mentioned manufacturing process, wire bonding was performed on the upper electrode 106.
However, when wire bonding was performed to the upper electrode 106 directly above the liquid chamber 102, the diaphragm 103 was broken by pressure. On the other hand, when the upper electrode 106 is extended in the depth direction of the liquid chamber, that is, the length of the liquid chamber in the depth direction is W, and the length of the upper electrode in the depth direction of the liquid chamber is Wu.
And W <Wu. Then, when wire bonding was performed on a portion where the substrate 101 was present under the upper electrode 106 (a portion where the liquid chamber 102 was not present), the operation was successfully performed. Therefore, it was found from the above results that the electrode extraction from the upper electrode 106 was facilitated by setting W <Wu.

Next, under the condition of Lu ≦ Lp <L1, the relationship with the length L of the liquid chamber 102 in the arrangement direction is optimized by examining the amount of deformation of the diaphragm 103 at the center of the liquid chamber. An experiment was performed. The materials and thicknesses of the diaphragm, lower electrode, PZT, and upper electrode were as described above.
Then, the center of the piezoelectric element was arranged at the center of the side in the liquid chamber arrangement direction so as to be bilaterally symmetric. The applied voltage between the upper and lower electrodes was 30 V. L = 100 μm fixed, L
Table 1 below shows the results when u, Lp, and L1 were changed.

[0056]

[Table 1]

As shown in Table 1 above, the magnitude relationship between the liquid chamber 102 and the PZT film 105 or the lower electrode 104 in the arrangement direction does not significantly affect the diaphragm deformation.
However, the magnitude relationship between the liquid chamber 102 and the upper electrode 106 affects the amount of deformation of the diaphragm. If the upper electrode 106 is larger than the liquid chamber 102, the amount of deformation of the diaphragm decreases. Based on this result, it is considered that if the deformed portion of the piezoelectric element is accommodated in the liquid chamber, the diaphragm can be efficiently deformed. The planar positional relationship that makes such a state is
In the liquid chamber arrangement direction, the length L of the liquid chamber in the arrangement direction> the upper electrode length L of the liquid chamber in the arrangement direction
u.

Under the planar size relationship described above,
Next, a liquid ejection experiment was performed. A water-based ink was used as the liquid. The length of the liquid chamber in the arrangement direction L (unit: μm), the length of the liquid chamber in the depth direction W (unit: μm), the thickness tp of the PZT film (unit: μm), and the thickness tv of the diaphragm (unit: μm) are used as parameters from the nozzle 109. The liquid ejection speed (unit: m / sec) was measured at a portion separated by 5 mm. The electric field applied to the PZT film was 5 V / μm. The diaphragm material, lower electrode material and thickness, upper electrode material and thickness, protective film material and thickness were as described above. The results are shown in Table 2 below.

[0059]

[Table 2]

Consider the following results.

First, L = 100 μm, W = 15000 μm
Under the condition that m and tv = 0.4 μm, tp = 0.8
In the case of μm, the liquid is ejected, and in the case of tp = 0.7 μm, the liquid is not ejected. This is considered to be because the pressure applied to the liquid in the liquid chamber is insufficient when tp = 0.7 μm. According to the teaching of material mechanics, the pressure applied to the liquid in the liquid chamber is generally proportional to the third power of tp + tv and inversely proportional to the third power of L. Therefore, when the above experimental results are applied to this condition, (tp + tv) ³ / L ³ ≧ 1.7 × 10 ⁻⁶ , that is, if (tp + tv) /L≧0.012, the range is set as the liquid in the liquid chamber. The applied pressure is
Anything that only sprays liquid can be given. Further, if the left side of the above inequality expression is increased, the liquid ejection characteristics are expected to be improved. In fact, when tp = tv = 3 μm, the liquid ejection speed of 17 m / sec is recorded.

However, when tp = 3 μm and tv = 5 μm, no liquid was jetted. This is because the diaphragm 103 is thickened and its rigidity is increased, so that the diaphragm 103 is not deformed by an amount sufficient to eject the liquid. Therefore, the diaphragm 103
Is too thick, it is undesirable to apply the numerical condition to the above inequality: (tp + tv) ³ / L ³ <5.12 × 10 ⁻⁴ , ie, (tp + tv) / L <0.08 Becomes This inequality means that the sum of the thickness tp of the PZT and the thickness tv of the diaphragm should be reduced in order to shorten the length L of the liquid chamber in the arrangement direction and increase the density of the nozzles of the liquid ejecting head. It is necessary. Conversely, by reducing tp + tv, L can be reduced and the nozzle density can be increased.

Now, in this state (tp = 3 μm, tv = 5
As a means for ejecting the liquid in a state of μm), it is conceivable to further increase the depth W of the liquid chamber in the depth direction. However, with such a configuration, the size of the liquid ejecting head becomes extremely large in plan view, which deviates from a practical range. Also, when W becomes large, the flow path resistance in the liquid chamber becomes large, and the operating speed of the liquid jet head decreases. Accordingly, for the planar miniaturization and high-speed operation of the liquid ejecting head, it is desirable that tp ≧ tv and W / L ≦ 150 from the above experimental results.

Further, L = 200 μm, tp = 4 μm, t
When v = 2 μm, liquid ejection is performed when W = 2000 μm, and liquid ejection is not performed when W = 1000 μm. This is W
This is because the depth of the liquid chamber for ejecting the liquid is too short at 1000 μm. Therefore, L = 200 μm
In the following, it was found that it is necessary to satisfy W / L ≧ 10 when arranging liquid chambers and increasing the density of nozzles.

The characteristics of the liquid ejecting head described above are summarized as follows.

Since PZT is used for the piezoelectric curtain 105, the liquid ejection efficiency is good. PZT has a large piezoelectric strain constant among piezoelectric materials, d ₃₁ = 150pC / N is achieved in the PZT in this embodiment. In the PZT of the present invention, the composition, the type and amount of the additive added in the above-described examples, and the type and amount of the compound which can be further dissolved are not limited in the above-mentioned practical examples. . Further, the forming method does not need to be limited to the above method.

The arrangement pitch of the liquid chambers 102 is
The arrangement pitch is the same as that of the above, so that a space for routing the liquid flow path 108 connecting the liquid chamber and the nozzle is not required, and the size of the liquid ejection head can be reduced. No increase in size is required.

By setting 10 ≦ W / L ≦ 150 and tp ≧ tv and 0.012 ≦ (tp + tv) / L <0.08, a liquid chamber having a narrow width can be formed using the thin diaphragm 103 and the PZT film 105. Even if it is formed, liquid ejection becomes possible, so that the size of the liquid ejection head can be reduced and the nozzle density thereof can be increased.

The substrate 101 is made of single crystal silicon having a plane orientation (110), and the depth direction of the liquid chamber 102 is set to a <1-12> or <−11 2> direction.
Of the side wall forming the side in the depth direction can be a (111) plane, so that the liquid chamber having a depth of 300 μm can be formed while suppressing the side etching in the arrangement direction to about 1 μm, and the liquid chamber dimension Can be made more accurate.

By setting Lu ≦ Lp <L1, it is possible to configure a piezoelectric element having no problem in the manufacturing process and having a suppressed leak current.

By setting L> Lu, the diaphragm can be efficiently deformed, and as a result, efficient liquid ejection becomes possible.

By setting W <Wu <Wp <W1,
This makes it possible to form a piezoelectric element having no problem in the manufacturing process and a reduced leakage current, and facilitates taking out of the electrode from the upper electrode.

The first in which the piezoelectric element and the liquid chamber 102 are formed
The shape and depth of the liquid flow path are controlled by joining and integrating the first substrate 101 and the second substrate 107 on which the liquid flow path 108 is formed so that the liquid chamber and the liquid flow path communicate with each other. In addition, the shape of the contact point between the liquid flow path and the liquid chamber can be made constant, the degree of freedom in design can be improved, and bubble accumulation and liquid ejection characteristics can be improved. It is possible to eliminate the cause of the variation.

The use of a nozzle at the opening of the cross section where the first substrate 101 and the second substrate 107 are joined eliminates the need for an expensive nozzle plate that was required as a separate component.

After the piezoelectric element is formed, means for protecting the surface on this side is provided, and the liquid chamber is formed from the opposite surface. Thus, the yield can be reduced even when a thin diaphragm and PZT are used. A liquid jet head can be formed well. In the present embodiment, the means for protecting the surface on the piezoelectric element side is by a jig, but the means is not limited to this, and other means such as applying a thick photoresist may be used. good.

The manufacturing method of joining the second substrate 107 having the liquid flow path formed thereon to the liquid chamber opening side of the first substrate 101 having the liquid chamber formed therein is used for sealing the substrate 101. In this case, it is possible to perform only one bonding process using one substrate (second substrate), and the cost of the liquid ejecting head can be reduced.

The manufacturing method is the same as the step of forming the silicon oxide layer 201 on the substrate 101 and removing the silicon oxide layer 201 formed in contact with the liquid chamber 102 in the same step as the step of forming the liquid chamber 102. It is possible to prevent the vibration plate 103 from being cracked or peeled off during the process, and the production yield of the liquid jet head is improved. Further, the influence of the silicon oxide layer 201 remaining when the diaphragm vibrates can be removed, and the liquid ejection characteristics can be improved.

Example 2 In order to obtain knowledge about the material of the diaphragm 103, the amount of deformation of the diaphragm at the center of the liquid chamber was examined by changing the material of the diaphragm in the structure of FIG. 2C. The lower electrode 104 does not perform any patterning, and is formed on the entire surface of the substrate 101. As a condition, L =
100 μm, Lp = 94 μm, Lu = 88 μm, W =
The applied voltage between the upper and lower electrodes was 15 V, tp = 3 μm, and tv = 1 μm.

As the material of the diaphragm 103, in addition to the nitrogen silicon used in Example 1 described above, silicon oxide formed by a thermal oxidation method, silicon obtained by thermally diffusing boron by 10 ²¹ cm ^-3 ,
Five kinds of zirconium oxide and aluminum oxide formed by a sputtering method were used. The results are shown in Table 3 below.

[0080]

[Table 3]

According to the following results, as the Young's modulus of the diaphragm 103 increases, the amount of deformation of the diaphragm increases. This indicates that when the Young's modulus of the vibration plate 103 is small, when the piezoelectric thin film is deformed in the horizontal direction, it is also greatly expanded in the horizontal direction, and the deformation in the vertical direction is not so large. In order to efficiently deform the diaphragm and eject the liquid, it is necessary to use a diaphragm having a large Young's modulus. In the case where silicon oxide is used, the volume becomes 1.5 × 10 ⁻¹³ m ³ , which is just around the exclusion volume required when performing liquid ejection using water-based ink. Therefore, the Young's modulus of the diaphragm is 1 × 10 ¹¹
If it is not less than N / m ^2, it is possible to eject the liquid with a margin, and if it is not less than 2 × 10 ¹¹ N / m ² , the amount of deformation of the diaphragm is significantly increased and the depth of the liquid chamber is increased. The length W in the direction can be reduced, and the size of the liquid ejecting head can be reduced, and the operation speed can be increased.

According to the above results, as the diaphragm material,
It is understood that zirconium oxide, nitrogen silicon, and aluminum oxide having large Young's modulus are desirable. In addition, titanium nitride, aluminum nitride, boron nitride, tantalum nitride,
Tungsten nitride, zirconium nitride, titanium nitride, silicon carbide, titanium carbide, tungsten carbide, and tantalum carbide have a Young's modulus of 2 × 10 ¹¹ N / m ² or more, and can be said to be desirable diaphragm materials.

Further, other components may be added with the above-mentioned material as a main component, or a material containing two or more kinds of the above-mentioned materials may be used. For example, tungsten carbide is the main component,
Titanium carbide, tantalum carbide, cemented carbide with a small addition of cobalt, titanium carbide or titanium carbonitride as the main component,
Cermet may be used for the diaphragm with a small amount of impurities added.

(Embodiment 3) FIG. 5 is a cross-sectional view of a substrate on which a piezoelectric element and a liquid chamber are formed in a liquid jet head having a laminated structure of a vibration plate according to an embodiment of the present invention.

In the figure, reference numeral 501 denotes a Young's modulus of 1 × 1.
It is a material layer of 0 ¹¹ N / m ² or more, desirably 2 × 10 ¹¹ N / m ² or more, and silicon nitride is used as in the above (Example 1). Reference numeral 502 denotes a silicon oxide layer, which was continuously formed after forming the nitrogen silicon layer 501 in the PECVD apparatus in which the nitrogen silicon layer 501 was formed. Other elements are the same as in the first embodiment.

By providing the silicon oxide layer 502, the adhesion between the lower electrode 104 and the diaphragm was enhanced. Further, the PZT film 105 generated at the time of heat treatment during the manufacturing process is used.
Since the stress applied to the substrate can be reduced, the production yield can be improved. 1 silicon nitride layer 501
The liquid ejection characteristics when the thickness of the silicon oxide layer 502 is set to 1000 ° are the same as those shown in Table 2 in the first embodiment.
The provision of the silicon oxide layer 502 did not deteriorate the liquid ejection characteristics.

This embodiment is desirably applied at a processing temperature of 710 ° C. or less when forming the PZT film or thereafter. This is because lead in the PZT film diffuses through the lower electrode 104 to the silicon oxide layer 502 of the diaphragm. Normally, silicon oxide is in a solid state in this temperature range. However, silicon oxide in which lead is diffused becomes liquid at 714 ° C. or higher, and this is ejected to the outside and destroys the liquid ejecting head. .

Embodiment 4 FIG. 6 is a cross-sectional view of a substrate in which a piezoelectric element and a liquid chamber are formed in a liquid ejecting head in which an aluminum oxide layer is inserted between a diaphragm and a lower electrode.

In the figure, an aluminum oxide layer 60 is placed on a diaphragm composed of a silicon nitride layer 501 and a silicon oxide layer 502.
1 is formed to a thickness of 1000 ° by a sputtering method,
A lower electrode 104 is formed from above. Other than that is the same as the third embodiment.

By forming the aluminum oxide layer 601, the diffusion of lead in the PZT into the diaphragm as described in the third embodiment can be suppressed. This allows 710
Even if a high-temperature heat treatment at a temperature of not less than ° C. is performed, it is possible to prevent the liquid ejecting head from being broken due to the external ejection of the silicon oxide layer 502, and to improve the production yield of the liquid ejecting head. Furthermore, since a high-temperature and high-temperature heat treatment of 710 ° C. or more can be performed efficiently, the piezoelectric characteristics of the PZT film can be further improved, and the liquid ejecting characteristics can be improved.

It has been found that the effect of providing the aluminum oxide layer 601 can be obtained by using other materials. As a result of the experiment, the effect was similarly confirmed by using zirconium oxide, tin oxide, zinc oxide, and titanium oxide in addition to the above aluminum oxide. Further, a material containing these as a main component and an additive, or a material containing two or more of these materials as a main component can be similarly applied.
Furthermore, this effect was confirmed not only for the diaphragm having a silicon oxide layer on the surface but also for a single-crystal silicon diaphragm containing boron.

(Embodiment 5) The present inventors have proposed that the lower electrode 104
The following experiment was performed to determine the configuration of

On a single crystal silicon substrate provided with a silicon oxide layer,
As the lower electrode 104, titanium and platinum were continuously formed in this order by a sputtering method. The thickness of the platinum was changed from 2000 ° and the thickness of the titanium was changed from 50 ° to 1000 °. Titanium is necessary to increase the adhesion between platinum as the electrode material and the silicon oxide layer as the diaphragm material.

Then, PZ was obtained by the method shown in the first embodiment.
T was formed to a thickness of 1 μm, and heat treatment was performed at 600 ° C. for 4 hours in an oxygen atmosphere.
It was formed by mask evaporation to a size of mm square.

In this sample, a voltage was applied between the upper and lower electrodes, and the withstand voltage characteristics of the PZT film were evaluated. here,
As a definition of the withstand voltage of the PZT film, the leakage current is 100
The applied voltage when nA flowed was taken. Table 4 shows the results.

[0096]

[Table 4]

From the above results, it is understood that there is a correlation between the titanium film thickness and the withstand voltage of the PZT film, and the withstand voltage increases as the titanium film thickness decreases. Further, according to observations made by the present inventors, fine projections were formed on the platinum surface, and the density of the projections increased as the titanium film thickness increased. For example, in the case of titanium 50 °, 20,000 pieces / m
m ² , but for titanium 200 mm 21
It was observed that it was about 0000 / mm ² . From this, it is considered that minute protrusions on the platinum surface formed by the heat treatment lower the withstand voltage of the PZT film.

By reducing the titanium film thickness from 100 ° to 80 °, the withstand voltage of the PZT film was greatly improved from 18V to 30V. If the withstand voltage of the PZT film is improved, the applied voltage can be increased, and the liquid ejecting characteristics of the liquid ejecting head can be improved. Further, even in a state where the PZT film is made thin, liquid ejection becomes possible, and productivity in manufacturing can be improved.

As for the withstand voltage value, if it is less than 10 V, it cannot withstand practical use, and if it is about 20 V, it is still insufficient. According to the above experimental results, the withstand voltage of the PZT film is significantly improved when the thickness of the titanium film layer is 80 ° or less. Therefore, it is desirable that the titanium film thickness be set to 80 ° or less, and the present inventors also set the titanium film thickness to 50 ° in the above-described embodiment.

In the above embodiment, the electrode material provided on titanium having a thickness of 80 ° or less is platinum, but this may be an alloy containing platinum. The inventors of the present invention continuously formed an alloy of titanium at 50 ° and 70 at% of platinum-30 at% of iridium on a single crystal silicon substrate provided with a silicon oxide layer by a sputtering method, and heat-treated at 600 ° C. for 4 hours in an oxygen atmosphere. The surface of this alloy after heat treatment was 8
Microscopic observation at a magnification of 00 showed that no microprojections on the surface were observed. PZT as in the previous embodiment
When a film was formed and the breakdown voltage was measured, a result of 70 V was obtained, and the characteristics were further improved.

The material of the diaphragm is not limited to single crystal silicon provided with a silicon oxide layer, but may be any material as mentioned in the above-described embodiments.

(Embodiment 6) FIG. 7 shows a piezoelectric element in a liquid jet head in which a hydrophilic material layer is formed on the surface of a liquid chamber.
It is sectional drawing of the board | substrate which formed the liquid chamber.

In the figure, reference numeral 701 denotes a hydrophilic material layer. The manufacturing method in this embodiment is almost the same as that in the first embodiment, except that the anisotropic etching of the single-crystal silicon substrate 101 is performed before the formation of the protective film 203, and then the temperature is set to 800 ° C.
By thermally oxidizing the surface of the substrate 101 at about the temperature,
The difference from the first embodiment is that silicon oxide is formed as the hydrophilic material layer 701. After that, a protective film 203 is formed on the surface on the piezoelectric element side.

The method for forming the hydrophilic material layer 701 is as follows.
Silicon oxide may be formed by SOG (Spin On Glass) or the like so as to cover the lower part of the diaphragm 103. Further, after assembling the liquid jet head, a liquid mixed with hydrophilic material particles is supplied to a liquid flow path or a liquid chamber. Through which the hydrophilic material particles may be left on the liquid flow path and the surface of the liquid chamber.

In such a configuration, when a water-based material such as aqueous ink is used for the liquid, the wettability between the liquid chamber and the liquid flow path and the liquid is improved, and the generation of bubbles is reduced. Become. At the same time, if a hydrophilic material such as glass is used for the second substrate 107, this effect is further improved.

Embodiment 7 FIGS. 8A and 8B show the second embodiment.
FIGS. 4A and 4B are a plan view and a cross-sectional view of a liquid jet head in which a nozzle is formed on a substrate 107 of FIG.

In the figure, a nozzle 801 is formed on a second substrate 107 on which a liquid flow path 108 is formed, and the nozzle 801 is joined to the first substrate 101. The nozzle 801 is
It may be formed by irradiating an excimer laser.

With such a configuration, FIG.
As shown in (a), the liquid chambers 102 can be arranged in a staggered manner, and the nozzles 801 can be arranged in a straight line. Therefore, the arrangement pitch of the nozzles 801 can be made half of the arrangement pitch of the liquid chambers 102. When the liquid chamber dimensions are set to 100 μm as in the first embodiment, the nozzle 80
1 can be further increased in density. In addition, since they can be arranged on a straight line, when recording a liquid such as ink on a medium such as paper, high-quality printing can be performed without causing a dot shift.

(Embodiment 8) FIG. 9 is a conceptual diagram of a liquid jet recording apparatus using the liquid jet head of the present invention.

In the figure, a liquid ejecting head 901 having a plurality of nozzles is connected to a control circuit (not shown) so that the control circuit drives the liquid ejecting head 901 appropriately to selectively eject ink. Has become. Information such as characters and images is recorded as a group of dots formed by ink droplets on a recording sheet 909 at a position facing the liquid jet head 901.

A cartridge 902 for storing ink is connected to the liquid ejecting head 901, and a guide rail 903 and a feed belt 904 are connected to the cartridge 902. Feed roller 905
When is rotated, the feed belt 904 is driven, and the liquid ejecting head 901 and the cartridge 902 move along the guide rail 903.

On the other hand, the recording paper 909 is
7 and the paper feed roller 908 so as to be in close contact with the platen 906. The liquid ejecting head 901 is scanned in the main scanning direction (the direction in which the liquid ejecting head 901 moves by the guide rail 903), and when recording is completed, the paper feed roller 908 is rotated stepwise, and the liquid ejecting head 901 is again rotated.
, The next recording is started.

This recording apparatus has the characteristics and effects of the liquid jet head described above as they are.

In this embodiment, the recording paper is used as the medium from which the ink is ejected. However, the recording medium is not limited to this, and may be a cloth or the like. Further, a three-dimensional object such as metal, resin, and wood may be used.

[0115]

As described above, the liquid ejecting head according to the present invention is suitable for a liquid ejecting recording apparatus for recording characters and image information on a recording medium such as paper, metal, resin, and fabric using ink. Used.

Further, taking advantage of the characteristics of small size, high density, and improved characteristics, it is most suitable as a recording head used in a small and high performance liquid jet recording apparatus.

[Brief description of the drawings]

FIG. 1 is a perspective view of a liquid jet head according to an embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views illustrating a manufacturing process until a piezoelectric element and a liquid chamber are formed on a first substrate 101. FIGS.

3A is a configuration diagram of a jig for protecting a surface of a substrate 101 on a piezoelectric element side during anisotropic etching of the substrate 101, and FIG. 3B is a cross-sectional view of a state where the substrate 101 is fixed to the jig. FIG.

FIG. 4 is a conceptual diagram of a mounting structure of a liquid jet head according to the present invention.

FIG. 5 is a cross-sectional view of a substrate on which a piezoelectric element and a liquid chamber are formed in a liquid jet head having a laminated structure of a vibration plate.

FIG. 6 is a cross-sectional view of a substrate on which a piezoelectric element and a liquid chamber are formed in a liquid jet head in which an aluminum oxide layer is inserted between a diaphragm and a lower electrode.

FIG. 7 is a sectional view of a substrate on which a piezoelectric element and a liquid chamber are formed in a liquid ejecting head in which a hydrophilic material layer is formed on the surface of the liquid chamber.

FIG. 8A is a plan view of a liquid jet head in which a nozzle is formed on a second substrate 107 of the present invention, and FIG. 8B is a cross-sectional view thereof.

FIG. 9 is a conceptual diagram of a liquid jet recording apparatus using the liquid jet head of the present invention.

[Explanation of symbols]

 101 first substrate 102 liquid chamber 103 diaphragm 104 lower electrode 105 piezoelectric film 106 upper electrode 107 second substrate 108 liquid flow path 109 nozzle

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 27, 2002 (2002.6.2
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

[0017]

2. Description of the Related Art Further, in an embodiment of the prior art,
One layer of SiO ₂ is used for the diaphragm. SiO ₂ has a Young's modulus as small as 10 ¹⁰ N / m ² , and when a piezoelectric thin film is formed thereon and a voltage is applied to deform the piezoelectric thin film in a horizontal direction, the piezoelectric thin film also expands in the horizontal direction at the same time. The deformation in the direction is not so large. That is, S
Even when a single layer of iO ₂ is used, it is impossible to efficiently deform the diaphragm and apply a liquid when applying a voltage to the piezoelectric film. Further, there is no mention of diaphragm characteristics or materials for efficiently ejecting liquid.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

[0020]

2. Description of the Related Art Torii et al. (Japanese Journal of Applied Physics, Vo1.30, No. 12B,
(December 1991, pages 3562 to 3566), a platinum film is formed directly on SiO ₂ as a lower electrode of a PZT film. However, it is a well-known fact that such a configuration has a problem in the adhesion between silicon oxide and platinum.
Peeling occurred between silicon oxide and platinum during film formation or subsequent heat treatment, or during operation after completion. Further, in order to solve the above problems and to improve the adhesion between the insulating material such as silicon oxide and platinum and platinum, as shown in Japanese Patent Publication No. 43435/1973, titanium is inserted between the platinum and the insulating material. Although it is known that the PZT film is formed, projections are formed on the surface of the platinum during the formation of the PZT film or during the subsequent heat treatment, and this reduces the withstand voltage of the PZT film.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has the following objects. (1) Enables efficient liquid ejection operation,
Provided is a liquid ejecting head which is small in a plane even when the number of nozzles is increased and has a high nozzle density. (2) To provide a liquid ejecting head which realizes a lower electrode having a small surface projection density, realizes a PZT film having a high withstand voltage, and improves liquid ejecting characteristics.

Continued on front page (31) Priority claim number Japanese Patent Application No. 5-57430 (32) Priority date March 17, 1993 (1993. 3.17) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 5-72426 (32) Priority date March 30, 1993 (1993.3.30) (33) Priority claim country Japan (JP) (31) Priority claim number 5-10226 (32) Priority date January 25, 1993 (1993.1.25) (33) Priority claiming country Japan (JP) (72) Inventor Masashi Sawada 3-5-5 Yamato, Suwa-shi, Nagano Prefecture No. Seiko Epson Corporation F-term (reference) 2C057 AF34 AF78 AG32 AG39 AG44 AG52 AG55 AP02 AP34 AP52 AP56 AP59 AQ02 BA03 BA14

Claims (8)

[Claims] A nozzle for discharging ink droplets, a liquid chamber formed in the substrate and communicating with the nozzle, a diaphragm constituting a part of the liquid chamber, a lower electrode formed on the diaphragm, In a liquid ejecting head including a piezoelectric film and a piezoelectric element including an upper electrode, the lower electrode is laminated on the diaphragm via an adhesive film, and the lower electrode is platinum or an alloy containing platinum. A liquid jet head, characterized in that: 2. The liquid jet head according to claim 1, wherein the adhesion film is titanium having a thickness of 80 ° or less. Is wherein Young's modulus of the diaphragm 1 × 10 ¹¹ N /
^3. The liquid jet head according to claim 1, wherein the liquid jet head is at least m ² , preferably at least 2 × 10 ¹¹ N / m ² . 4. The vibrating plate is made of silicon nitride, titanium nitride, aluminum nitride, boron nitride, tantalum nitride, tungsten nitride, zirconium nitride, zirconium oxide, titanium oxide, aluminum oxide, silicon carbide, titanium carbide, tungsten carbide, tantalum carbide. 4. The liquid jet head according to claim 3, wherein the liquid jet head is a material containing at least one of the following as a main component. 5. The diaphragm has a Young's modulus of 1 × 10 ¹¹ N.
/ M ² or more, desirably 2 × 10 ¹¹ N / m ² or more, and a silicon oxide layer having a two-layer structure.
The liquid ejecting head according to claim 1, wherein the liquid ejecting head is disposed on a lower electrode side. 6. A material layer mainly comprising at least one of aluminum oxide, zirconium oxide, tin oxide, zinc oxide and titanium oxide is provided between the diaphragm and the lower electrode. The liquid jet head according to any one of claims 1 to 5, wherein 7. The liquid jet head according to claim 1, wherein the piezoelectric film is made of lead zirconate titanate. 8. A liquid jet recording apparatus comprising the liquid jet head according to claim 1.