JP2000109398A - Composite titanium oxide film element unit and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite titanium oxide thin film element unit obtained by easily and inexpensively forming a composite titanium oxide film in fine pattern form on the prescribed area of a substrate, and to provide the method for producing the unit. SOLUTION: This composite titanium oxide film element unit is obtained by providing a substrate in which at least its surface layer contains, as main component, Ni-P (nickel-phosphorus), then forming a film of titanium or titanium-containing material on the prescribed area of the substrate and selectively forming the composite titanium oxide layer only on the film surface of titanium or titanium-containing material by a hydrothermal method. The method for producing the composite titanium oxide film element unit is comprised of forming a Ni-P protective film on the prescribed area on a substrate containing titanium and selectively forming the composite titanium oxide film on the part without the protective film by the hydrothermal method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condenser, a detector for detecting infrared rays and ultrasonic waves, an ink jet recording head, an actuator such as a micropump, a piezoelectric buzzer, a piezoelectric speaker and the like. The present invention relates to a composite titanium oxide thin film element unit in which a composite titanium oxide thin film is finely or precisely formed at a desired position on a substrate by a thermal synthesis method, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, communication equipment, information processing equipment, AV,
At the same time as high performance and miniaturization of home electric appliances and the like are progressing, miniaturization and weight reduction of electronic components constituting those devices are being studied, and attempts have been made to improve performance by thinning.

[0003] However, in the conventional thinning method using a ceramic polishing method, although a desired density and composition can be obtained, the yield is poor and the cost is extremely increased in order to form a desired thickness (3 to 50 µm). However, it is not suitable for forming a piezoelectric crystal film in a free shape such as a curved surface.

A thin film can be formed by using a physical vapor deposition method such as a sputtering method, a CVD method, or a vapor deposition method, or a sol-gel method. Poor mass production
There is a problem that the substrate material is limited because it passes through a high temperature of 00 ° C. or higher.

As means for solving the above problems, recently, a method of forming a composite titanium oxide film by heat treatment in a solution containing an alkali under a low temperature environment of 200 ° C. or less has been actively studied.

This method is described in, for example, "Preparation of PZT Crystal Film by Hydrothermal Synthesis and Its Electrical Properties" in Proceedings of the 15th Electronic Materials Research Seminar of the Ceramic Society of Japan (published October 2, 1995). In general, the method includes a seed crystal forming process of depositing a PZT seed crystal on the surface of a titanium metal substrate, and a crystal growth process of further depositing and growing a PZT crystal on the PZT seed crystal.

Japanese Patent Application Laid-Open No. Hei 8-306980 discloses a method for manufacturing a piezoelectric element unit by a hydrothermal synthesis method. The method disclosed herein is to form a film containing titanium in a predetermined region on a substrate not containing titanium such as stainless steel and to form a piezoelectric film only in that region by a hydrothermal method. is there. On the other hand, a method is disclosed in which a protective film of gold, platinum, iridium, and Teflon is formed on a substrate containing titanium, and a piezoelectric film is formed only on a portion where titanium is exposed.

[0008]

However, even if a substrate containing no titanium is used as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-306980, crystals of the composite titanium oxide are deposited in unnecessary portions. And there are various problems. For example, the stainless steel substrate used in the examples of the above publication has poor corrosion resistance to the hot alkaline solution used in the present invention, elution of chromium ions is observed, and the surface is deteriorated. Furthermore, when the reaction is performed for a long time to increase the thickness of the composite titanium oxide to be formed, or when the reaction is repeatedly performed,
The composite titanium oxide adheres and grows on the entire surface of the deteriorated stainless steel substrate, and a desired fine pattern cannot be formed.

In the method of forming a protective film such as a gold or platinum layer on a predetermined region of a substrate containing titanium, the protective film is expensive and not practical. In addition, when the temperature of the Teflon protective film is repeatedly increased and decreased in the steps of seed formation and growth film formation, the protective film peels off due to a difference in thermal expansion with the substrate material, and the function as the protective film is impaired, and the pattern itself is lost Disappear.

Accordingly, the present invention solves such a problem, and a composite titanium oxide thin film element unit in which a composite titanium oxide film is formed in a predetermined area on a substrate in a fine pattern easily and inexpensively, and a method of manufacturing the same. The purpose is to provide.

[0011]

Means for Solving the Problems In a method for selectively forming a composite titanium oxide film on a substrate by a hydrothermal method, the present inventors provide a substrate and a protective film for preventing the formation of a composite titanium oxide film. Have been studied diligently, and have led to the present invention.

That is, according to the present invention, there is provided a substrate in which at least the main component of the surface is Ni-P (nickel phosphorus), and a film of titanium or a material containing titanium is formed in a predetermined region of the substrate. A composite titanium oxide film element unit comprising a composite titanium oxide layer selectively formed by a hydrothermal method on a surface of a film containing a material containing:

Further, according to the present invention, a film of titanium or a material containing titanium is formed at least in a predetermined region of a substrate whose main component is Ni-P (nickel phosphorus), and a film of titanium or a material containing titanium is formed. Selectively on the surface of the membrane
The present invention relates to a method for manufacturing a composite titanium oxide film element unit, wherein a composite titanium oxide layer is formed by a hydrothermal method.

Further, the present invention provides a step of forming a protective film mainly containing Ni-P (nickel phosphorus) on a substrate, and a step of forming a film containing Ti in a partial region on the protective film. ,
Selectively forming a composite titanium oxide film on a film containing Ti by a hydrothermal method.

Further, according to the present invention, a protective film containing Ni-P (nickel phosphorus) as a main component is formed on a surface of a substrate made of titanium or a material containing titanium in a region where a composite titanium oxide film is not formed. The present invention also relates to a method for manufacturing a composite titanium oxide film element unit, wherein a composite titanium oxide thin film is selectively formed in a region where no protective film is formed on a substrate.

In one embodiment of the present invention, Ni
It is preferable that the method of forming the protective film containing -P (nickel phosphorus) as a main component is a plating method.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a film of titanium or a material containing titanium is formed on a predetermined region of a substrate whose main surface is at least Ni-P (nickel phosphorus), and this film contains titanium or titanium. A method for manufacturing a composite titanium oxide film element unit characterized by selectively forming a composite titanium oxide layer on the surface of a film of a material by a hydrothermal method will be described.

As a substrate, at least the surface is made of Ni-P
It is only necessary that the substrate be made of a material mainly containing (nickel phosphorus), and a film mainly containing Ni-P is formed on a substrate mainly containing Ni-P (nickel phosphorus) or a substrate other than Ni-P. May be formed. In this case, an optimal substrate such as a thickness and a material may be selected according to the intended use. For example, metals such as nickel, titanium, copper, and iron, and alloys thereof (such as stainless steel) are preferably used. In addition, a polymer, glass, silicon, or the like can be used as the substrate as long as conductivity can be ensured. Further, the substrate is not limited to a planar substrate. It is sufficient that Ni and P are contained in a total of 80% by weight or more.

The method for forming a film containing Ni-P as a main component on the surface of the substrate is not particularly limited, but for example, a plating method is preferable. In the case of performing the plating method, first, the substrate whose surface has been clarified or pretreated is immersed in a nickel plating bath using sodium hypophosphite as a reducing agent together with the counter electrode, and the reaction temperature is 20 ° C. or higher, and the solution pH = Under 4 to 11, a nickel-plated protective film containing phosphorus is formed on the entire surface of the substrate until a desired film thickness is obtained. The thickness of this protective film may be not less than the thickness that exhibits the crystal adhesion preventing effect of the composite titanium oxide, and is preferably 50 nm or more, although it depends on the conditions of the hydrothermal reaction. It is also possible to isolate only the Ni-P film thus formed and use it as an electroformed nickel phosphorus substrate. Since the higher the phosphorus content of the Ni—P film is, the higher the effect of suppressing the precipitation of the composite titanium oxide film is,
A higher phosphorus content is preferred. The phosphorus content of the Ni-P plating formed by the normal plating method is about 3 to 16% by weight, and more preferably 5% by weight or more.

Examples of the nickel plating bath using sodium hypophosphite as a reducing agent include an acidic electroless nickel plating bath, an alkaline electroless nickel plating bath, a low-temperature electroless nickel plating bath, and the like. The optimal combination can be selected depending on the amount.

Next, a layer containing titanium is patterned in a desired shape on the nickel protective layer containing phosphorus or on the Ni-P substrate. As the layer containing titanium, T
i element may be included. In addition to metal Ti, titanium oxide, T
An i-containing perovskite ceramic may be used. Examples of the method for forming the titanium layer include a film forming method such as a sputtering method and a vacuum evaporation method. Further, as a method for forming a desired shape, a method using a shadow mask when forming a titanium layer on a substrate by a sputtering method or a vacuum evaporation method, or using a photolithography after forming a titanium layer on the entire surface of the substrate To form a desired shape. The thickness of the titanium layer is desirably 0.01 to 5 μm, preferably 0.1 to 1.0 μm.

On the patterned titanium layer, composite titanium oxide crystals are formed by a hydrothermal method as follows. ATiO ₃ (where A is P
b, Ba, Sr, and Ca) as well as A (Zr, Ti) O ₃ (where A is Pb, B
a, Sr, or Ca), or any other perovskite-type composite oxide containing Ti.

The hydrothermal method is a method of obtaining a target compound by heating a compound containing a film-forming element in an aqueous alkaline solution. In the case of a perovskite-type composite oxide, the solution is practically 80 to 3 in an alkaline aqueous solution containing the above-mentioned constituent elements such as Pb, Ba, Sr, Ca, Zr, and Ti.
By heating at a temperature of about 00 ° C., the target compound can be obtained. Here, PZT (lead zirconate titanate) and two stages of seed crystal formation and crystal growth,
An example in which a film in which a part of Pb is substituted with Sr or Ba will be described, but a one-step reaction or a multi-step reaction can also be used.

In a 0.1 mol / l to 8.0 mol / l alkali solution, the amount of the lead-containing starting compound is 50 mmol / l or less.
500 mmol / l, zirnium-containing starting compound is 10
mmol / l to 500 mmol / l, the titanium-containing raw material compound is 0 mmol / l to 500 mmol / l, and the strontium and / or barium-containing raw material compound is 0.0
The substrate was placed and fixed in a mixed solution prepared to have a concentration of 1 mmol / l to 500 mmol / l,
° C, preferably 100 to 160 ° C, more preferably 1 to
The reaction is performed at 20 to 160 ° C. for 1 minute or more, preferably 10 minutes or more, to form an initial crystal layer on the patterned titanium layer. At this time, since the nickel plating film containing phosphorus, which is a protective film, has high corrosion resistance to the reaction solution, no reaction occurs, and a composite titanium oxide seed crystal is formed only in the titanium layer.

Next, 0.1 mol / l to 8.0 mol
/ Mm alkaline solution contains 50 mmol of lead-containing starting compound
l / l to 500 mmol / l, zirnium-containing raw material compound is 10 mmol / l to 500 mmol / l, and
10 mmol / l to 500 mm of titanium-containing raw material compound
ol / l, 80-200 ° C., preferably 100
The reaction is carried out at a temperature of about 160 ° C., more preferably 120 ° C. to 160 ° C. for 1 minute or more, preferably 10 minutes or more to produce a composite titanium oxide crystal film forming a crystal growth layer. In this reaction as well, the nickel plating film containing phosphorus, which is a substrate protective film, does not react with the raw material solution because of high corrosion resistance, and no crystal growth on the protective film is observed. Therefore, the pattern of the composite titanium oxide crystal is accurately formed. Furthermore, the thickness of the composite titanium oxide can be controlled by repeating the crystal growth reaction.

Lead used in the hydrothermal reaction in the present invention,
As the compound containing the constituent elements of zirconium, titanium, strontium, and barium, chloride, oxychloride, nitrate, hydroxide, oxide, and the like are preferable. Examples of the alkali compound include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

A specific example of the present invention will be described in detail below. For example, a nickel substrate is used as a substrate. First, a nickel-plated protective layer containing phosphorus is formed on the surface of the substrate by nickel plating using sodium hypophosphite as a reducing agent. A titanium base layer is formed on the upper surface of the protective layer by a sputtering method, and the titanium layer is patterned into a desired shape by a photolithography technique. Next, an initial composite titanium oxide crystal layer is formed on the patterned titanium layer by a hydrothermal reaction in an alkaline solution, and further, by a hydrothermal reaction in the alkaline solution,
A composite titanium oxide crystal film having a fine and accurate pattern and improved electrical properties such as a dielectric constant, a dielectric loss, and a piezoelectric constant is manufactured.

First, a protective film is formed on a substrate by plating, for example, as follows. Nickel chloride 30g /
l, sodium citrate 15 g / l, sodium acetate 5
g / l, 10 g / l sodium hypophosphite, 2 ppm Pb ion, and prepare an acidic electroless nickel plating bath.
= 4.2, 60-90 ° C., 10-15 minutes, forming a nickel plating protective film on the substrate. At this time, the thickness of the nickel protective film containing phosphorus is about 0.5 to 2.0 μm.

Next, after a titanium layer is formed on the substrate on which the protective film is formed by sputtering, the titanium layer is formed into a desired shape by using a photolithography technique. The thickness of this titanium layer is about 0.1 to 1 μm.

Next, in order to form an initial crystal layer, the following steps are taken.
In a 1 mol / l to 8.0 mol / l alkaline solution, the lead-containing raw material compound is 50 mmol / l to 500 mmol /
l, zirnium-containing starting compound is 10 mmol / l to 5
00 mmol / l, 0 mmol of titanium-containing starting compound
/ L to 500 mmol / l, the strontium and / or barium-containing starting compound is 0.01 mmol / l to
The substrate is placed and fixed in a mixed solution prepared to have a concentration of 500 mmol / l.
0 to 160 ° C, more preferably 120 to 160 ° C.
The reaction is performed for at least 10 minutes, preferably at least 10 minutes, to form an initial crystal layer on the patterned titanium layer. At this time, the thickness of the initial composite titanium oxide crystal layer is 0.05 to 2.0 μm.

Next, in order to grow the crystal, 0.1 mol
/ L to 8.0 mol / l alkaline solution, lead-containing raw material compound is 50 mmol / l to 500 mmol / l, zirnium-containing raw material compound is 10 mmol / l to 500 mm.
ol / l and titanium-containing raw material compound is 10 mmo
Under the condition of 1 / l to 500 mmol / l, 80 to 200
° C, preferably 100 to 160 ° C, more preferably 1 to
The reaction is performed at 20 to 160 ° C. for 1 minute or more, preferably 10 minutes or more, to produce a composite titanium oxide crystal film that forms a crystal growth layer. The heating method in the hydrothermal reaction uses a hot water bath, an electric furnace, or the like. Thereafter, general cleaning is performed. For example, ultrasonic cleaning is performed in pure water and dried at 100 to 200 ° C. for 2 hours or more. Organic acids such as acetic acid, nitric acid, sulfuric acid and the like can be used for washing.

The composition of the piezoelectric crystal film thus formed is
The first layer of the initial crystal layer is lead titanate, lead zirconate, strontium titanate and or barium titanate,
The composite oxide is a solid solution of strontium zirconate and / or barium zirconate. The composition of the PZT-based piezoelectric crystal film grown on the initial crystal layer is PbZr
_x Ti _{1 -x} O ₃ (where 0 <x <1).

The electrode used when converting the PZT-based piezoelectric crystal film obtained in the present invention into an element is not particularly limited, but an optimum one is selected in consideration of cost and mass productivity. For example, there are nickel by electroless plating and silver of a baking type. In addition, aluminum by vapor deposition, platinum, gold, nickel and the like by sputtering are also used. When a resin is used for the substrate, it is not possible to heat the substrate to a high temperature.

Next, a Ni-P (nickel-phosphorus) protective film is formed on at least a region of the surface of the substrate made of titanium or a material containing titanium where the composite titanium oxide film is not formed. A method for selectively forming a composite titanium oxide thin film in a region having no region will be described.

In this case, the substrate may be a substrate containing Ti, which serves as a nucleus for seed crystal precipitation at least on the surface, and may be a Ti metal plate itself. In a region where the composite titanium oxide film is not formed on this substrate, for example, a Ni-P protective film is formed by the plating method described above. As a method of plating a predetermined area, there is a method such as masking. Next, as described above, when the seed crystal of the composite titanium oxide film and its growth layer are formed by the hydrothermal method, Ni
No film is formed on the -P protective film, and a composite titanium oxide film having a predetermined pattern can be formed, and the composite titanium oxide film element unit of the present invention can be obtained. By forming the electrodes by the above-mentioned method, it can be used for various applications such as a piezoelectric element and a capacitor.

[0036]

EXAMPLES Hereinafter, specific examples of the present invention will be described in more detail.

Example 1 Nickel chloride 30 g / l, sodium citrate 15 g /
l, sodium acetate 5 g / l, sodium hypophosphite 1
An acidic electroless nickel plating bath of 0 g / l and 2 mg / l of lead nitrate was prepared, and a nickel plating protective film was formed on the entire surface of a 20 μm stainless substrate under the conditions of pH = 4.2, 90 ° C., and 10 minutes. . At this time, the thickness of the nickel protective film containing phosphorus was a uniform plating film having a thickness of 1.0 μm. As a result of X-ray analysis, the composition of this protective film was 90.6% by weight of Ni, 8.9% by weight of P, and 0.5% by weight of Na.

Next, a titanium layer was formed by sputtering on the upper surface of the substrate on which the protective film had been formed, and then formed into a desired shape using photolithography. The thickness of this titanium layer was 0.5 μm.

In order to form an initial PZT crystal layer on the titanium layer of the substrate patterned as described above, the input amount of the reaction raw material was 150 mmol / l of Pb (NO ₃ ) ₂ aqueous solution, Sr
(NO ₃ ) ₂ aqueous solution 50 mmol / l, ZrOCl ₂ aqueous solution 75 mmol / l, TiCl ₄ aqueous solution 25 mmol / l
and a KOH aqueous solution of 4.15 mol / l. The substrate with the protective film was fixed in the mixed solution, and a heat treatment reaction was performed at 150 ° C. for 4 hours under a normal stirring operation.
The composition of the initial crystal layer generated in this step is Pb _x Sr _{1 over x} Z
r _y Ti _1-y O3 (provided that 0 <x <1, 0 <y <1).

In the initial crystal layer obtained in this manner, the amount of the reaction raw material charged for crystal growth was adjusted to the Pb (NO ₃ ) ₂ aqueous solution 3
30 mmol / l, 150 mmol ZrOCl ₂ aqueous solution
/ L, 150 mmol / l TiCl ₄ aqueous solution, and K
An OH aqueous solution was adjusted to 5.06 mol / l, and a substrate with a protective film having an initial PZT crystal layer was installed and fixed in the mixed solution, and a heat treatment reaction was performed at 130 ° C. for 4 hours under a normal stirring operation. This step was repeated three times to make the film thickness 10 μm. After that, perform ultrasonic cleaning in pure water twice for 3 minutes,
Drying was performed at 100 ° C. for 12 hours.

The composition of the obtained PZT-based piezoelectric crystal growth film layer was PbZr _x Ti _1-x O ₃ (where 0 <x <1). FIG. 1 shows the surface state of the obtained composite titanium oxide film element unit. In FIG. 1, the portion that looks black is the region of the Ni-P protective film, and the portion that looks white is the composite titanium oxide film formed on Ti. No attached crystal particles were found on the protective film, indicating that the pattern was formed finely and accurately.

Comparative Example 1 In Example 1, a Ti layer was formed on a predetermined region of a 20 μm stainless substrate in the same manner as in Example 1 except that nickel phosphorus plating was not performed, and a PZT thin film was formed. FIG. 2 shows the surface state of the obtained composite titanium oxide film element unit. The target pattern is described in Example 1.
Although it is the same as above, it can be seen that a PZT film is also formed on the surface of the stainless steel substrate on which Ti is not formed, a composite titanium oxide film is formed on the entire surface, and a precise pattern cannot be formed.

Comparative Example 2 In Example 1, nickel plating was performed in the following manner in place of nickel phosphorous plating.
In the same manner as described above, Ti was formed, and a PZT film was formed. Nickel plating was performed as follows. Nickel chloride 0.0
2 mol / l, sodium tartrate 0.02 mol / l,
A nickel plating bath using hydrazine of 1 mol / l hydrazine as a reducing agent was adjusted to have a pH of 10, a temperature of 95 ° C, and a temperature of 95 ° C.
Under a condition of 0 minute, a nickel plating protective film was formed on the entire surface of the 20 μm stainless steel foil. The nickel protective film was a uniform plating film having a thickness of 1.5 μm. As a result of X-ray analysis, the composition of this protective film was 98.4% by weight of Ni and N
It was 1.6% by weight. FIG. 3 shows the surface state of the obtained composite titanium oxide film element unit. Although the amount of the PZT crystal deposited on the protective film is smaller than that formed directly on the stainless steel substrate, the PZT crystal is partially deposited, indicating that a precise pattern cannot be formed.

[0044]

According to the present invention, when forming a composite titanium oxide film in a fine pattern in a predetermined region on a substrate to obtain a composite titanium oxide thin film element unit, an expensive protective film such as platinum or gold is not used. Also, there is no separation problem such as Teflon, and even under severe conditions, there is no precipitation of the composite titanium oxide on the protective film, and the composite titanium oxide film can be formed on the substrate in a precise pattern. it can.

[Brief description of the drawings]

FIG. 1 is a photograph instead of a drawing showing a surface state of a composite titanium oxide film element unit obtained by forming a PZT thin film on a substrate having a Ni—P protective film obtained in Example 1.

FIG. 2 is a photograph instead of a drawing showing a surface state of a composite titanium oxide film element unit obtained by forming a PZT thin film on a substrate having no Ni—P protective film obtained in Comparative Example 1.

FIG. 3 is a photograph instead of a drawing showing a surface state of a composite titanium oxide film element unit obtained by forming a PZT thin film on a substrate having a Ni protective film obtained in Comparative Example 2.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 41/187 H01L 41/18 101D 41/24 41/22 A F term (Reference) 4G077 AA03 BC42 CB03 ED06 EE06 EF01 HA11 KA15 4K044 AB05 BA02 BA06 BA12 BA19 BB04 BB10 BC14 CA13 CA15 CA62 5E082 AB03 BC40 FG03 FG26 FG27 FG41 KK01

Claims (5)

[Claims] 1. A substrate having at least a main component of Ni-P (nickel phosphorus) on a surface, and a film of titanium or a material containing titanium formed on a predetermined region of the substrate. A composite titanium oxide film element unit comprising a composite titanium oxide layer selectively formed on a surface of the film by a hydrothermal method. 2. A film of titanium or a material containing titanium is formed at least in a predetermined region of a substrate whose main component is Ni-P (nickel phosphorus), and a film of titanium or a material containing titanium is formed on a surface of the film. A method for manufacturing a composite titanium oxide film element unit, comprising selectively forming a composite titanium oxide layer by a hydrothermal method. 3. A step of forming a protective film containing Ni-P (nickel phosphorus) as a main component on a substrate, a step of forming a film containing Ti in a partial region on the protective film, and a hydrothermal method. Selectively forming a composite titanium oxide film on a film containing Ti in the method described above. 4. A region of a substrate made of titanium or a material containing titanium where a composite titanium oxide film is not formed,
A composite titanium oxide film element comprising: forming a protective film containing Ni-P (nickel phosphorus) as a main component; and selectively forming a composite titanium oxide thin film in a region where the protective film is not provided on the substrate. Unit manufacturing method. 5. The composite oxide thin film element unit according to claim 3, wherein the method of forming the protective film containing Ni—P (nickel phosphorus) as a main component is a plating method. Production method.