JPS6197159A - Solution for manufacturing piezoelectric thin film and manufacture of film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solution for producing a piezoelectric thin film and a method for producing a piezoelectric thin film.

``Prior art'' ``Problems to be solved by the invention'' Sintered bodies containing lead and titanium oxides, which are attracting attention as piezoelectric materials, especially electroceramics, have already been used as ignition elements and speakers. Currently, they are widely used in various electrical appliances as ultrasonic transducers and filters. For these piezoelectric materials, efforts are being made to make them smaller in size or thinner, aiming for higher frequency applications or new functions.In particular, thin film piezoelectric materials are being used for surface wave filters and optical anisotropy. It is a material that is expected to be applied to electrical spectroscopic devices that utilize .

However, when using this piezoelectric thin film material using conventional sintering technology, the molded body must be sliced and polished, which makes the processing process complicated and expensive.
Furthermore, it is difficult to increase the size, there is a limit to the film thickness, and since the large particles are large, it is difficult to maintain strength, and it is difficult to apply them to other substrates.

On the other hand, methods using vacuum techniques such as evaporation, sputtering, and ion blating allow for arbitrary film thickness and precise formation on substrates, and are attracting attention as important technologies for forming electronics-related materials. , piezoelectric thin films are also being actively investigated using this method. However, piezoelectric thin films made using this vacuum technology are quite difficult to stably produce aWN9 with the desired stoichiometric composition, especially in the case of metal compositions higher than Ht, and for this reason they are completely different from bulk materials. It is well known that this is a physical property. It is also known that it is difficult to produce results for complex shapes or large areas, and that it is expensive due to equipment costs and poor productivity due to the batch method. A method for producing thin films is expected.

"Means for Solving the Problems" In view of the above circumstances, the present invention provides a novel solution for manufacturing a piezoelectric body with a thickness of 1 odor and a method for manufacturing the same, which can solve the problems of the above-mentioned thin film forming method.

That is, the first aspect of the present invention is Ll selected from lead and lanthanum.
An organometallic compound solution containing a metal with ffi or higher and one or more metals selected from titanium and zirconium,
The second aspect of the present invention is a piezoelectric material thickness Jli manufacturing solution characterized in that the functional group of the organometallic compound consists of an alkoxy group and a β-diketone group. A solution for producing a piezoelectric thin film, characterized in that the functional group of the organometallic compound consists of an alkoxy group and a β-diketone group, the third aspect of the present invention is an organometallic compound solution containing one or more metals selected from lead and lanthanum and one or more metals selected from titanium and zirconium, the organometallic compound having functional groups such as an alkoxy group and a β-diketone group. A piezoelectric body i1j! A piezoelectric body characterized by immersing a metal, glass, or ceramic substrate in a manufacturing solution, pulling it out at a constant speed into a humid atmosphere, drying it, and then heat-treating it at a temperature of 400°C or higher and 1200°C or lower. A method for producing a thin film, the fourth aspect of the present invention is an organometallic compound solution containing lithium and one or more metals selected from tantalum, niobium, and vanadium, the organometallic compound having functional groups such as an alkoxy group and a β- A piezoelectric material composed of diketone groups 'RIIj! A piezoelectric device characterized in that a metal, glass, or ceramic substrate is immersed in F6 manufacturing liquid, pulled out at a constant speed into a humid atmosphere, dried, and then heat-treated at a temperature of 400°C or higher and 1200°C or lower. Each content is a method for manufacturing body thin films.

It is important that the main component of the organometallic compound used in the present invention is a metal alkoxide that easily decomposes through hydrolysis or thermal decomposition, but if it is composed only of gold mud alkoxide, it is sensitive to moisture and easily decomposes. Since it is stable and has poor long-term stability, it is necessary to have a composition in which some functional groups are replaced with β-diketone groups from alkoxy groups, or to use a metal β-diketone complex in combination.

Furthermore, if each metal alkoxide or metal β-diketone complex is simply mixed in a solvent, individual gold-N oxides may be produced as impurities during thermal decomposition in addition to the desired composite metal oxide. In many cases, by subjecting the mixed solution to reflux treatment for a sufficient period of time, a single-phase composite oxide can be obtained by thermal decomposition.
If a β-diketone used for stabilization causes an insoluble precipitate, or if a β-diketone complex with low solubility is used, an aldehyde of less than the number of moles of β-diketone may be added. A stable solution can be obtained by adding and refluxing.

For these reasons, the transparent piezoelectric material thinning solution of the present invention can be produced using the following three methods.

A metal alkoxide is mixed in a solvent to obtain a desired composition ratio, and β-diketone is added to stabilize the mixture. Preferably, the metal alkoxide is mixed in a solvent, heated to reflux sufficiently, and then β-diketone is added to stabilize the mixture.

■, Metal alkoxide and metal β to achieve the desired composition ratio.
- The diketone complex is mixed in a solvent and preferably heated to reflux.

1 [[, If the solubility of the metal β-diketone complex is low in the precipitation in method I or in the method
Heat to reflux to make a homogeneous and stable solution.

The organometallic compound used in the present invention is a metal alkoxide selected from lead, lanthanum, titanium, zirconium, lithium, quantal, niobium, and vanadium, which are metals necessary for piezoelectric compounds, and a metal β-diketone complex. As alkoxides, these metals have a carbon number of 2
0 or less monovalent and polyhydric alcohol, preferably carbon number 5
The following reaction products with alcohols and metal β-diketone complexes include acetylacetone, benzoylacetone, dipivaloylmethane, diisobutyrylmethane,
A reactant of 3-methylpentane-2 dione is used, preferably an acetylacetone complex.

The use of metal alkoxides and metal β-diketone complexes can be selected depending on the stability of the metal alkoxide and the difficulty of production. 1 of the organic functional groups of
It is desirable that 74 or more are alkoxy groups.

In addition, the β-diketones added to stabilize the solution are the aforementioned β-diketones, and acetylacetone is particularly preferred. Similarly, the amount added is such that the alkoxy group accounts for 1/4 or more of the total organic functional groups. It is desirable to add.

Formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde are preferable as aldehydes used to improve solubility in the solvent when β-diketone complexes and β-diketones are added. Particularly good results are obtained by using formaldehyde and paraformaldehyde. It will be done.

Examples of the solvent used in the present invention include aromatic solvents such as lfi or polyhydric alcohols, carboxylic acid esters, ketones, and Hensen, and one type or a mixed solvent of two or more types of ethers. In particular, lower alcohols, lower Acetate ester, tetrahydrofuran, etc. are versatile, but
It may be selected as appropriate depending on the combination of metal alkoxide and metal β-diketone complex.

By immersing a substrate in the F6 piezoelectric film forming solution of the present invention and drawing it out into the humid atmosphere at a constant speed, the alkoxy groups contained in the solution are hydrolyzed and the thin film adhered to the substrate is formed. After drying this film at a temperature below the boiling point of the solvent, it is heated in an oxidizing atmosphere to a temperature of 400° C. or higher and 1200° C. or lower, thereby obtaining a transparent piezoelectric thin film having the desired composition on the substrate.

The substrate material for forming the thin film only needs to have rI4 thermal properties that can withstand the temperature of heat treatment, and examples include glass, ceramics, metals, and even heat-resistant polymers such as polyimide.

As a combination of metals exhibiting piezoelectricity, for example, lead titanate (PbTj03
), PZT (PbZrxTil-x03) PL
ZT ((Ph, -shi" 1-x) (zry T
Piezoelectric oxides such as ii-y) 03) are obtained, and by combining lithium with a metal selected from tantalum, niobium, and vanadium, piezoelectric oxides such as lithium tantalate (1-+Ta03) and lithium niobate (L+Nb0) are obtained.
3)-Lithium vanadate (LiVO3) is obtained.

In addition, trace elements used to improve piezoelectric properties, such as zinc, manganese, antimony, bismuth, iron, gallium, indium, chromium, cobalt, nickel, aluminum, magnesium, tin, calcium, barium,
It goes without saying that strontium, cerium, yttrium, tungsten, etc. may be added as long as they are in the form of metal alkoxide or metal β-diketone complex compounds.

"Effect of the invention" According to the invention, l) It becomes easy to form a film over a large area and a complicated shape.

2) A dense piezoelectric thin film with a smooth surface can be obtained.

3) A piezoelectric thin film with extremely excellent transparency, which is difficult to obtain with a sintered molded body, can be obtained.

4) Since the desired metal composition is placed on the substrate in advance and thermally decomposed, the desired f! A thin film having a stoichiometric ratio can be easily obtained, and the composition ratio can be freely adjusted.

5) Compared to conventional sintering processes, the desired piezoelectric compound thin film can be obtained with low-temperature heat treatment.

6) Production can be performed in a continuous process, resulting in better productivity and lower film-forming costs than batch systems using vacuum technology.

This provides many advantages that cannot be obtained with conventional techniques such as.

Hereinafter, the present invention will be explained in more detail using the actual alP11, but it goes without saying that the present invention is not limited to the examples.

Example 1 25.0 g of diisopropoxy lead, 16.2 g of zirconium tetrabutoxide, and 9.8 g of titanium tetraisopropoxide were sufficiently dehydrated so that the ratio of pb:Zr:Ti was 11.55:0.45. Melt it in 150g of ethyl alcohol, and further dissolve it at the boiling point of ethyl alcohol.
After refluxing for a period of time, 5.0 g of acetylacetone was added to obtain a pressure 11151 coating solution. When this solution was left in a tightly closed glass container at room temperature for about 3 months, no change occurred (it was stable).

A piece of quartz glass was immersed in this coating solution, lifted into the atmosphere at a rate of 15 cm/min, dried at room temperature for 30 minutes, and then fired in a Matsufuru furnace at 600°C for 1 hour, resulting in a slightly grayish transparent thin film. The resulting film thickness was measured using a step needle and found to be about 100 OA. Even after applying this method two more times and increasing the thickness to about 3oooA, the transparency of the film hardly changed, and as a result of elemental analysis using an X-ray microanalyzer, the ratio of Pb:Zr:Ti was 1:0.591.41.
It was confirmed that the desired composition was obtained as a thin film. Further, as a result of X-ray diffraction, the thin film fired at 600°C showed a PZT crystal pattern, and the thin film fired at 450°C was amorphous.

Example 2 Element ratio of Pb + La: Zr: Ti is 0.92
:O.

os:o, ss:o, 3s (lead diacetylacetonate) 29.9 g, lanthanum triacetylacetonate 2.8g, zirconium tetrabutoxide 20
．． When 0 g of titanium tetraisopropoxide and 8.0 g of titanium tetraisopropoxide were added to 150 g of anhydrous ethyl alcohol and stirred, it was not completely dissolved and the insoluble scuttling occurred.

Then, 1.0 g of paraformaldehyde was added and refluxed for 4 hours at the boiling point of ethyl alcohol, resulting in a yellowish transparent solution, which was stable at room temperature for more than 3 months.

This solution was applied and heated on quartz glass under the same conditions as in Example 1 to obtain a transparent thin film with a thickness of about 3000 Å. When the elemental composition of SOt was measured using an energy dispersive scanning electron microscope, it was found to be Pb:La:Zr:Ti-1:0
．． 1:0.7=0.4, which is consistent with the composition in the Habo solution, and further structural analysis by X-ray diffraction revealed a single perovskite structure.
It was concluded that a PLZTaN film was obtained.

Example 3 10.6 g of lithium acetylacetonate and 38.8 g of niobium bentite propoxide were dissolved in 100 g of anhydrous isopropyl alcohol and refluxed for 2 hours at the boiling point of isopropyl alcohol to obtain a colorless and transparent solution.

When this solution was applied on a quartz substrate in the same manner as in Example 1, an amorphous structure was obtained at a firing temperature of 500°C or lower, and a crystalline transparent lithium niobate thin film was obtained at a firing temperature of 650°C or higher. Ta.

Claims (1)

[Scope of Claims] 1. An organometallic compound solution containing one or more metals selected from lead and lanthanum and one or more metals selected from titanium and zirconium, wherein the organometallic compound has an alkoxy functional group. A solution for producing a piezoelectric thin film characterized by comprising a group and a β-diketone group. 2. An organometallic compound solution containing lithium and one or more metals selected from tantalum, niobium, and vanadium, the organometallic compound having functional groups such as alkoxy groups and β
- A solution for producing a piezoelectric thin film characterized by comprising a diketone group. 3. An organometallic compound solution containing one or more metals selected from lead and lanthanum and one or more metals selected from titanium and zirconium, the organometallic compound having functional groups such as an alkoxy group and a β-diketone group. A metal, glass or ceramic substrate is immersed in a piezoelectric thin film production solution consisting of a solution, pulled out at a constant speed into a humid atmosphere, dried, and then heat-treated at a temperature of 400°C or higher and 1200°C or lower. A method for producing a characteristic piezoelectric thin film. 4. An organometallic compound solution containing lithium and one or more metals selected from tantalum, niobium, and vanadium, the organometallic compound having functional groups such as alkoxy groups and β
- A metal, glass or ceramic substrate is immersed in a solution for producing a piezoelectric thin film consisting of a diketone group, pulled out at a constant speed into a humid atmosphere, and then dried at 400°C.
A method for producing a piezoelectric thin film, characterized in that heat treatment is performed at a temperature of 1200° C. or less.