JPH10287983A - Production of titanium-containing ceramic thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and swiftly form Ti-contg. ceramic thin film having regulated crystal orientation properties on all substrates by forming a Ti compound layer on a substrate, forming amorphous ceramic precursor film thereon and crystallizing this. SOLUTION: The Ti compound layer formed on the substrate itself contributes to the formation of crystal nuclei and has operation of promoting the subsequent growth of crystals. In this way, crystal nuclei having high density are formed on the substrate side, the growth of crystals progresses in one direction toward the direction of the surface of film on the upper layer, and the crystallization is completed. Therefore, the obtd. crystalline film is not formed into polycrystalline film but into Ti-contg. ceramic thin film excellent in crystal orientation properties. The Ti compound layer to be formed on the substrate is composed of any of a metallic Ti layer, a TiO2 layer and a lead titanate layer, and the thickness of this layer is regulated to <=10 nm. Furthermore, the amorphous ceramic precursor film can be formed by applying a sol using an organic metallic compound as a raw material and executing drying.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic thin film, which is a main component of a thin film device utilizing physical properties derived from crystallinity (piezoelectricity, pyroelectricity, ferroelectricity, etc.). In particular, regarding a method of manufacturing a ceramic thin film containing titanium, the obtained ceramic thin film is widely applied to electronic devices.

[0002]

2. Description of the Related Art The physical properties of a ceramic thin film material and the device characteristics when it is incorporated as a component of an electronic device are greatly affected by the crystallinity and orientation of the ceramic thin film. The method of forming a crystalline thin film is roughly classified into two types. One is to form a crystalline film having a uniform orientation on a single crystal substrate or a substrate and epitaxially grow a desired ceramic thin film thereon. Another method is to form an amorphous film, which is a precursor of a desired crystalline film, on a substrate and then apply external energy by firing or light irradiation to form a crystalline thin film. What you get. This is a film forming method represented by a so-called post-annealing method.

[0003]

However, both of the above two types of film forming methods have problems. First, in the case of a film forming method by epitaxial growth, it is necessary to select a film having a crystal lattice constant of a substrate (or a crystal film formed thereon) close to a lattice constant of a desired ceramic thin film.
There is a problem that the degree of freedom in material selection is small or there is no suitable substrate in some cases. Also,
In general, epitaxial growth has a low film forming rate, and a film requiring a relatively large thickness takes too much film forming time, which is not suitable for mass production.

On the other hand, in the case of the post-annealing method, in this method, crystal nuclei are randomly generated throughout the film during the transition from the amorphous film to the crystalline film. There is a problem that it becomes a crystal film, and it is extremely difficult to control the target crystal orientation.

[0005] However, the post-annealing method also has an advantage that it is suitable for mass production because of its simple manufacturing process. Accordingly, the present inventors have focused on this post-annealing method and have conducted intensive research to overcome the conventional disadvantages. As a result, the present inventors have found a method for solving the above-described problems with respect to a ceramic thin film containing titanium as a constituent element. It was reached. That is, an object of the present invention is to provide a method for easily and quickly forming a titanium-containing ceramic thin film having a controlled crystal orientation on any substrate.

[0006]

According to the present invention, there is provided a method for producing a titanium-containing ceramic thin film.
(i) forming a compound layer; (2) forming an amorphous ceramic precursor film on the titanium compound layer; and (3) crystallizing the same. I do. Further, the method for producing a titanium-containing ceramic thin film of the present invention comprises the step of forming a titanium (T
i) The compound layer is one of a metal titanium (Ti) layer, a titanium oxide (TiO2) layer, and a lead titanate (PbTiO3) layer. In the method for producing a titanium-containing ceramic thin film according to the present invention, the thickness of the titanium (Ti) compound layer formed on the substrate is 10 nm or less. The method for producing a titanium-containing ceramic thin film of the present invention is characterized in that the formation of the amorphous ceramic precursor film is achieved by applying and drying a sol made of an organometallic compound as a raw material. I do. Further, the method for producing a titanium-containing ceramic thin film of the present invention includes: (1) a step of forming a titanium (Ti) compound (eg, titanium metal, titanium oxide) layer on a substrate; A step of applying and drying a sol containing lead and zirconium, and not containing titanium,
(3) a step of repeating a step of applying and drying a sol containing lead, zirconium and titanium n times (n is an integer of 1 or more); and (4) a step of crystallizing the same. . Further, the method for producing a titanium-containing ceramic thin film of the present invention comprises the following steps: 1) forming a titanium (Ti) compound (eg, titanium metal, titanium oxide) layer on a substrate;
(2) a step of applying and drying a sol containing lead and zirconium but not containing titanium on the titanium compound layer; (3) a step of crystallizing the sol; (4) a lead, zirconium and titanium Repeating the step of applying and drying a sol containing n times (n is an integer of 1 or more);
(5) crystallizing this.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS By going through the steps described above,
The thin titanium compound layer itself formed on the substrate has a function of contributing to the generation of crystal nuclei and promoting subsequent crystal growth. Thus, it is considered that high-density crystal nuclei are generated on the substrate side (near), and crystal growth proceeds in one direction toward the surface of the upper layer to complete crystallization. for that reason,
The resulting crystalline film does not become a polycrystalline film, but becomes a titanium-containing ceramic thin film having excellent crystal orientation.

The operation has been briefly described above, but the present invention will be described in more detail with reference to the following examples.

(Example 1) A silicon wafer (diameter: 4 inches, thickness: 250 μm) was prepared by forming Pt to a thickness of 0.2 μm by sputtering, and this was used as a substrate to be used later. On the other hand, a sol solution containing a predetermined concentration of lead acetate and titanium tetraisopropoxide was prepared to obtain a sol solution 1.

On the prepared Pt film of the substrate, a titanium (Ti) layer having a thickness of about 5 nm is further formed by sputtering.
The sol solution 1 was applied thereon by spin coating. 180
After drying in an oven at 350 ° C for 10 minutes,
By performing degreasing for a minute, an amorphous film having a thickness of about 0.2 μm was obtained on the substrate. On top of this, sol solution 1
Coating, drying and degreasing four times, the total film thickness is about 1.0
A μm amorphous film was obtained. This is put in an electric furnace in air atmosphere 5
Baking was performed at 00 ° C. for 30 minutes to perform crystallization (Sample 1). On the other hand, a sample according to the conventional method was also prepared for comparison.
That is, the sol solution 1 is applied directly on Pt by spin coating without forming a Ti layer on the substrate, and the obtained thickness is about 1.
The 0 μm amorphous film was crystallized by firing in an air atmosphere at 500 ° C. for 30 minutes in an air atmosphere (Comparative Example 1).

As a result of crystal analysis by X-ray diffraction for both sample 1 and comparative example 1, a perovskite-type PbTiO3
It was found that a (PT) thin film was obtained. Further, in order to examine the crystal orientation of both, a rocking curve of X-ray diffraction was measured for the PT (111) plane. The incident angle of the X-ray to the sample surface is θ, and the deviation from θ is Δω (Δ
θ). In sample 1, Δω (Δθ) = ± 10 °
When the diffraction intensity from the (111) plane was measured within the range, a very sharp peak having a half width of about 1 ° centered on Δω = 0 ° was observed (FIG. 1). From this, it can be seen that in Sample 1, a PT film having extremely strong orientation was obtained. This is considered to be because the Ti layer formed first on the substrate acts as a crystal growth starting point, and crystal growth proceeds in the vertical direction from the substrate side toward the surface layer. On the other hand, in Comparative Example 1,
Within the range of Δω (Δθ) = ± 10 °, the diffraction intensity from the (111) plane was almost constant, and it was found that this PT film was a polycrystalline film having random orientation (FIG. 2). Thus, a remarkable difference in crystal structure was observed between Sample 1 and Comparative Example 1.

As shown in this embodiment, when a titanium (Ti) (compound) layer is formed on a substrate and then an amorphous layer is formed thereon and crystallized, an amorphous layer is formed. Near)
High density crystal nuclei are formed in the substrate,
It is considered that crystal growth proceeds in one direction toward, and crystallization is completed. Therefore, the obtained crystalline film does not become a polycrystalline film as in the related art, but becomes a ceramic thin film having excellent crystal orientation. In this example, an example of producing a PT film by the so-called sol-gel method was shown. However, the same effect as in this example was confirmed for other compositions and amorphous precursor film formation methods (such as sputtering). Was. Also, the crystallization method is described in the present embodiment in the case of the most standard heating and firing method.However, without being limited to this, any method of crystallizing by supplying energy from the outside including laser irradiation is widely and generally used. It can be applied and the effects of the present invention can be obtained.

Example 2 A silicon wafer (4 inches in diameter, 250 μm in thickness) having Pt formed in a thickness of 0.2 μm by sputtering was prepared and used as a substrate to be used later. On the other hand, a sol solution containing a predetermined concentration of lead acetate, zirconium acetylacetonate and titanium tetraisopropoxide was prepared, and was referred to as sol solution 1.

A titanium oxide (TiO 2) layer having a thickness of about 5 nm was further formed on the prepared Pt film of the substrate by sputtering, and a sol solution 1 was applied thereon by spin coating. After drying in a 200 ° C. oven for 10 minutes, degrease in a 400 ° C. oven for 30 minutes to obtain a thickness of about 0.2 μm.
m amorphous films were obtained on the substrate. Further on this,
The application, drying and degreasing of the sol solution 1 were repeated four times to obtain an amorphous film having a total thickness of about 1.0 μm. This was fired at 800 ° C. for 1 minute in an oxygen atmosphere by a rapid temperature rising lamp annealing apparatus (RTA) to crystallize (sample 1). On the other hand, a sample according to the conventional method was also prepared for comparison. That is, the sol solution 1 is applied directly on Pt by spin coating without forming a TiO2 layer on the substrate, and the obtained amorphous film having a thickness of about 1.0 μm is subjected to RTA at 800 ° C. in an oxygen atmosphere. It was baked for a minute and crystallized (Comparative Example 1).

When the crystallized films of Sample 1 and Comparative Example 1 obtained as described above were analyzed by X-ray diffraction, they were found to be perovskite-type Pb (Zr0.5, Ti0.5) O3 (PZT). did.

Now, PZT is a piezoelectric material, and in order to construct a thin film device utilizing this piezoelectricity, it is naturally desirable that the piezoelectric constant (d31) showing its characteristic has a large value. Therefore, in order to evaluate the piezoelectric characteristics of Sample 1 and Comparative Example 1, an Al electrode having a thickness of 0.1 μm was formed on each of the upper portions by vapor deposition, and a piezoelectric constant was obtained from the measurement of the electromotive force between this and a Pt electrode on the substrate. (D31) was determined. Table 1 shows the results.

As apparent from Table 1, the piezoelectric constant of Sample 1 was larger than that of Comparative Example 1, indicating that a thin film PZT having very excellent piezoelectric characteristics was obtained. When the crystal orientation was examined by X-ray rocking curve measurement in the same manner as in Example 1 described above, the PZT (111)
While the normal vector of the plane was oriented in the direction perpendicular to the substrate, Comparative Example 1 was randomly oriented. It is considered that such a difference in crystal structure appears as a difference in piezoelectric characteristics.

As shown in this embodiment, when a titanium oxide (TiO 2) layer is formed on a substrate and then an amorphous layer is formed thereon and crystallized, an amorphous layer is formed on the substrate side (near). It is considered that high-density crystal nuclei are generated, and crystal growth proceeds in one direction in a direction perpendicular to the substrate (thickness direction) to complete crystallization. Therefore, the obtained crystalline film did not become a polycrystalline film as in the prior art, but became a ceramic thin film having excellent crystal orientation, and as a result, the electrical characteristics (piezoelectric characteristics) of the obtained film were improved. In this embodiment, an example is shown in which attention is paid to the piezoelectric characteristics of a PZT film manufactured by a so-called sol-gel method.
Experiments were performed on other compositions and amorphous precursor film formation methods (such as sputtering), and the same effects as in this example were confirmed. It was possible to improve the physical properties of the thin film. Regarding the crystallization method, the present embodiment described the case of the most standard heating and firing method.However, without being limited to this, a method of crystallizing by supplying energy from the outside including laser irradiation is generally widely used. Anything can be applied, and the effects of the present invention can be obtained.

[0019]

[Table 1]

(Example 3) A silicon wafer (4 inches in diameter, 250 μm in thickness) having Pt formed in a thickness of 0.2 μm by sputtering was prepared and used as a substrate to be used later. On the other hand, a sol solution containing a predetermined concentration of lead acetate, zirconium acetylacetonate and titanium tetraisopropoxide was prepared, and was referred to as sol solution 1.

A titanium oxide (TiO2) layer was further formed on the prepared Pt film of the substrate by sputtering. At this time, six samples were prepared in which the thickness of the TiO2 layer was changed (samples 1-3 and comparative examples 1-3, a total of six). Each Ti
The thickness of the O2 layer is as shown in Table 2. The sol solution 1 was spin-coated on each of these six levels of substrates. After drying in a 200 ° C. oven for 10 minutes, degrease in a 400 ° C. oven for 30 minutes to obtain a thickness of about 0.2 μm.
m amorphous films were obtained on the substrate. Further on this,
The application of the sol solution, drying and degreasing were repeated four times to obtain an amorphous film having a total film thickness of about 1.0 μm. This was fired at 800 ° C. for 1 minute in an oxygen atmosphere by a rapid temperature rising lamp annealing apparatus (RTA) to perform crystallization.

The crystallized films of Samples 1 to 3 and Comparative Examples 1 to 3 obtained above were analyzed by X-ray diffraction. As a result, perovskite-type Pb (Zr0.5, Ti0.5) O3
(PZT).

Now, PZT is a piezoelectric material, and in order to construct a thin film device utilizing this piezoelectricity, it is naturally desirable that the piezoelectric constant (d31) showing its characteristic has a large value. Therefore, in order to evaluate the piezoelectric characteristics of each sample, an Al electrode having a thickness of 0.1 μm was formed on each of the samples by vapor deposition.
The piezoelectric constant (d31) was determined from the measurement of the electromotive force between this and the Pt electrode on the substrate. Table 2 shows the results.

As is clear from Table 2, the underlying TiO2
The piezoelectric constants of Samples 1 to 3 having a layer thickness of 10 nm or less are larger than those of Comparative Examples 1 to 3 (the TiO2 layer is thicker than 10 nm), and the thin film P having very excellent piezoelectric properties is obtained.
It was found that ZT was obtained. When the crystal orientation was examined by X-ray rocking curve measurement in the same manner as in Example 1 described above, the normal vectors of the PZT (111) planes of Samples 1 to 3 were oriented in the direction perpendicular to the substrate. Example 1
In No. 3, the alignment was random. It is considered that such a difference in crystal structure appears as a difference in piezoelectric characteristics.

As shown in this embodiment, when a titanium oxide (TiO2) layer is formed on a substrate and then an amorphous layer is formed thereon and crystallized, the thickness of the TiO2 layer is particularly high. When the thickness is 10 nm or less, it is considered that high-density crystal nuclei are generated on the substrate side (near), crystal growth proceeds in one direction toward the substrate vertical direction (film thickness direction), and crystallization is completed. Therefore, the obtained crystalline film does not become a polycrystalline film as in the past, but becomes a ceramic thin film having excellent crystal orientation, and the electrical characteristics (piezoelectric characteristics) of the resulting film are obtained.
Improved. A similar effect was confirmed when titanium metal was used as the titanium compound on the substrate. In this embodiment, an example was described in which attention was paid to the piezoelectric characteristics of a PZT film manufactured by a so-called sol-gel method. However, when an experiment was performed for another composition or an amorphous precursor film formation method (such as sputtering), The same effect as that of the present example was confirmed, and it was possible to improve thin film physical properties such as piezoelectricity, pyroelectricity, and ferroelectricity. Regarding the crystallization method, the present embodiment described the case of the most standard heating and firing method.However, without being limited to this, a method of crystallizing by supplying energy from the outside including laser irradiation is generally widely used. Anything can be applied, and the effects of the present invention can be obtained.

[0026]

[Table 2]

Example 4 A silicon wafer (4 inches in diameter, 250 μm in thickness) having Pt formed in a thickness of 0.2 μm on a silicon wafer was prepared and used as a substrate to be used later. On the other hand, a sol solution containing a predetermined concentration of lead acetate, zirconium acetylacetonate and titanium tetraisopropoxide was prepared, and was referred to as sol solution 1.
In addition, a sol solution containing a predetermined concentration of lead acetate and titanium tetraisopropoxide was also prepared, and a sol solution 2 was obtained.

The sol solution 2 is formed on the prepared Pt film of the substrate.
Was applied by spin coating. After drying in a 200 ° C. oven for 10 minutes, degreasing was performed in a 400 ° C. oven for 30 minutes to form an amorphous film on the substrate. At this time, the coating conditions of the sol solution 2 were changed to produce films having different film thicknesses as shown in Table 3 (Samples 1 to 3, Comparative Examples 1 to 3). Further, a sol solution 1 is applied thereon by spin coating,
After drying in an oven for 10 minutes, degreasing was performed in a 400 ° C. oven for 30 minutes. Further, by repeating the application, drying and degreasing of the sol solution 1 four times, an amorphous film having a total film thickness of about 1.0 μm was obtained. This is a rapid temperature ramp lamp annealing system (RTA)
For 1 minute at 800 ° C. in an oxygen atmosphere for crystallization. On the other hand, a sample according to the conventional method was also prepared. That is, the sol solution 2 was not used, and the sol solution 1 was applied directly on Pt on the substrate by spin coating, and the obtained thickness was about 1.0.
The μm amorphous film was crystallized by firing at 800 ° C. RTA in an oxygen atmosphere for 1 minute (Comparative Example 4).

Samples 1 to 3 obtained above and Comparative Example 1
Each of the crystallized films Nos. To 4 was analyzed by X-ray diffraction. As a result, the obtained crystallized films were Samples 1 to 3 and Comparative Examples 1 to
In No. 3, perovskite type PbTiO3 (PT) and Pb
It turned out that it has a two-layer structure of (Zr0.5, Ti0.5) O3 (PZT). On the other hand, in Sample 4, the obtained crystallized film was a perovskite-type Pb (Zr0.5, Ti0.5) O3 (PZ
T).

Now, PZT (PT) is a piezoelectric material, and in order to construct a thin film device utilizing this piezoelectricity, it is naturally desirable that the piezoelectric constant (d31) showing its characteristic has a large value. Therefore, in order to evaluate the piezoelectric characteristics of Sample 1 and Comparative Example 1, an Al electrode having a thickness of 0.1 μm was formed on each of the upper portions by vapor deposition, and a piezoelectric constant was obtained from the measurement of the electromotive force between this and a Pt electrode on the substrate. (D31) was determined. Table 3 shows the results.

As is clear from Table 3, the piezoelectric constants of Samples 1 to 3 in which the thickness of the underlying PT is 10 nm or less are Comparative Examples 1 to 3 (thickness of the PT is larger than 10 nm) or Comparative Example 4 (PT (No layer), indicating that a thin film PZT having very excellent piezoelectric properties was obtained. The crystal orientation was examined by X-ray rocking curve measurement in the same manner as in Example 1 described above.
While the normal vector of the ZT (111) plane was oriented in the direction perpendicular to the substrate, Comparative Examples 1 to 4 were randomly oriented. It is considered that such a difference in crystal structure appears as a difference in piezoelectric characteristics.

As described above, as shown in this embodiment, P
When the T precursor layer is formed, especially the thickness of the PT layer is 10 n
In the crystallization step, first, a high-density crystal nucleus is generated on the substrate side (near) in the crystallization step, and the nucleus is used as a seed for the amorphous film formed thereon. It is considered that the crystal growth proceeds in one direction (thickness direction) and the crystallization is completed. Therefore, the obtained crystalline film did not become a polycrystalline film as in the prior art, but became a ceramic thin film having excellent crystal orientation, and as a result, the electrical characteristics (piezoelectric characteristics) of the obtained film were improved. In this embodiment, an example was described in which attention was paid to the piezoelectric characteristics of a PZT film manufactured by a so-called sol-gel method. However, when an experiment was performed for another composition or an amorphous precursor film formation method (such as sputtering), The same effect as that of the present example was confirmed, and it was possible to improve thin film physical properties such as piezoelectricity, pyroelectricity, and ferroelectricity. Regarding the crystallization method, the present embodiment described the case of the most standard heating and firing method.However, without being limited to this, a method of crystallizing by supplying energy from the outside including laser irradiation is generally widely used. Anything can be applied, and the effects of the present invention can be obtained.

[0033]

[Table 3]

Example 5 A silicon wafer (diameter: 4 inches, thickness: 250 μm) was prepared by forming Pt to a thickness of 0.2 μm by sputtering, and this was used as a substrate to be used later. On the other hand, a sol solution containing a predetermined concentration of lead acetate, zirconium acetylacetonate and titanium tetraisopropoxide was prepared, and was referred to as sol solution 1.
In addition, a sol solution containing a predetermined concentration of lead acetate and zirconium acetylacetonate was also prepared to obtain a sol solution 2.

A titanium oxide (TiO2) layer having a thickness of about 5 nm was formed on the prepared Pt film of the substrate by sputtering, and a sol solution 2 was applied thereon by spin coating. 2
After drying in a 00 ° C. oven for 10 minutes, degreasing was performed in a 400 ° C. oven for 30 minutes to obtain an amorphous film having a thickness of about 10 nm on the substrate. Further, the sol solution 1 was applied thereon by spin coating, dried in a 200 ° C. oven for 10 minutes, and then degreased in a 400 ° C. oven for 30 minutes.
Further, by repeating the application, drying and degreasing of the sol solution 1 four times, an amorphous film having a total film thickness of about 1.0 μm was obtained. This is heated in an oxygen atmosphere by a rapid temperature rising lamp annealing apparatus (RTA) 8
Crystallization was performed by baking at 00 ° C. for 1 minute (sample 1). On the other hand, a sample according to the conventional method was also prepared for comparison.
That is, titanium oxide (Ti
The O2) layer is not formed or the sol solution 2 is not applied, but the sol solution 1 is applied directly on the Pt on the substrate by spin coating, and the obtained amorphous film having a thickness of about 1.0 μm is subjected to RTA at 800 ° C. For 1 minute in an oxygen atmosphere to crystallize (Comparative Example 1).

The crystallized films of Sample 1 and Comparative Example 1 obtained above were each analyzed by X-ray diffraction. as a result,
The obtained crystallized film was a perovskite type Pb (Zr0.5,
Ti0.5) O3 (PZT).

Now, PZT is a piezoelectric material, and in order to construct a thin film device utilizing this piezoelectricity, it is naturally desirable that the piezoelectric constant (d31) showing its characteristics has a large value. Therefore, in order to evaluate the piezoelectric characteristics of Sample 1 and Comparative Example 1, an Al electrode having a thickness of 0.1 μm was formed on each of the upper portions by vapor deposition, and a piezoelectric constant was obtained from the measurement of the electromotive force between this and a Pt electrode on the substrate. (D31) was determined. Table 4 shows the results.

As apparent from Table 4, the piezoelectric constant of Sample 1 was larger than that of Comparative Example 1, and it was found that a thin film PZT having very excellent piezoelectric characteristics was obtained. When the crystal orientation was examined by X-ray rocking curve measurement in the same manner as in Example 1 described above, the PZT (111)
While the normal vector of the plane was oriented in the direction perpendicular to the substrate, Comparative Example 1 was randomly oriented. It is considered that such a difference in crystal structure appears as a difference in piezoelectric characteristics.

As shown in this embodiment, when a titanium compound layer is formed on a substrate, and a precursor layer containing Pb and Zr is formed thereon and crystallized, first, the substrate side (near)
A high-density PZT crystal nucleus is generated, and crystal growth proceeds in one direction in the direction perpendicular to the substrate (thickness direction) with respect to the amorphous film formed thereon as a seed. Is considered complete. Therefore, the obtained PZT crystal film did not become a polycrystalline film as in the related art, but became a ceramic thin film having excellent crystal orientation, and as a result, the electrical characteristics (piezoelectric characteristics) of the obtained film were improved. The same effect was confirmed when a titanium metal layer was formed on a substrate. In this embodiment, an example was described in which attention was paid to the piezoelectric characteristics of a PZT film manufactured by a so-called sol-gel method. However, when an experiment was performed for another composition or an amorphous precursor film formation method (such as sputtering),
The same effect as that of the present example was confirmed, and it was possible to improve thin film physical properties such as piezoelectricity, pyroelectricity, and ferroelectricity. Regarding the crystallization method, the present embodiment described the case of the most standard heating and firing method.However, without being limited to this, a method of crystallizing by supplying energy from the outside including laser irradiation is generally widely used. Anything can be applied, and the effects of the present invention can be obtained.

[0040]

[Table 4]

Example 6 A silicon wafer (4 inches in diameter, 250 μm in thickness) having Pt formed in a thickness of 0.2 μm by sputtering was prepared and used as a substrate to be used later. On the other hand, a sol solution containing a predetermined concentration of lead acetate, zirconium acetylacetonate and titanium tetraisopropoxide was prepared, and was referred to as sol solution 1.
In addition, a sol solution containing a predetermined concentration of lead acetate and zirconium acetylacetonate was also prepared to obtain a sol solution 2.

A titanium oxide (TiO2) layer having a thickness of about 5 nm was formed on the prepared Pt film of the substrate by sputtering, and a sol solution 2 was applied thereon by spin coating. 2
After drying in a 00 ° C. oven for 10 minutes, degreasing was performed in a 400 ° C. oven for 30 minutes to obtain an amorphous film having a thickness of about 10 nm on the substrate. This was baked at 800 ° C. for 1 minute in an oxygen atmosphere by a rapid temperature rising lamp annealing apparatus (RTA). Further, the sol solution 1 is applied thereon by spin coating, dried in a 200 ° C. oven for 10 minutes, and then dried at 400 ° C.
Degreasing was performed in an oven for 30 minutes. Further, by repeating the application, drying and degreasing of the sol solution 1 four times, the total film thickness becomes about 1.
An amorphous film of 0 μm was obtained. This was fired at 800 ° C. for 1 minute in an oxygen atmosphere by a rapid temperature rising lamp annealing apparatus (RTA) to crystallize (sample 1). On the other hand, a sample according to the conventional method was also prepared for comparison. That is, the formation of a titanium oxide (TiO2) layer by sputtering on the substrate, the application of the sol solution 2, and the crystallization are not performed, and the sol solution 1 is directly applied on Pt on the substrate by spin coating, and the obtained thickness is obtained. About 1.
A 0 μm amorphous film was formed in an oxygen atmosphere at 800 ° C. RTA for 1 minute.
It was baked for a minute and crystallized (Comparative Example 1).

The crystallized films of Sample 1 and Comparative Example 1 obtained above were each analyzed by X-ray diffraction. as a result,
The obtained crystallized film was a perovskite type Pb (Zr0.5,
Ti0.5) O3 (PZT).

Now, PZT is a piezoelectric material, and in order to construct a thin film device utilizing this piezoelectricity, it is naturally desirable that the piezoelectric constant (d31) showing its characteristics has a large value. Therefore, in order to evaluate the piezoelectric characteristics of Sample 1 and Comparative Example 1, an Al electrode having a thickness of 0.1 μm was formed on each of the upper portions by vapor deposition, and a piezoelectric constant was obtained from the measurement of the electromotive force between this and a Pt electrode on the substrate. (D31) was determined. Table 5 shows the results.

As is clear from Table 5, the piezoelectric constant of Sample 1 was larger than that of Comparative Example 1, indicating that a thin film PZT having very excellent piezoelectric characteristics was obtained. When the crystal orientation was examined by X-ray rocking curve measurement in the same manner as in Example 1 described above, the PZT (111)
While the normal vector of the plane was oriented in the direction perpendicular to the substrate, Comparative Example 1 was randomly oriented. It is considered that such a difference in crystal structure appears as a difference in piezoelectric characteristics.

As shown in the present embodiment, when a titanium compound layer is formed on a substrate and a precursor layer containing Pb and Zr is formed thereon and crystallized, first, the substrate side (near)
A high-density PZT crystal nucleus is generated, and crystal growth proceeds in one direction in the direction perpendicular to the substrate (thickness direction) with respect to the amorphous film formed thereon as a seed. Is considered complete. Therefore, the obtained PZT crystal film did not become a polycrystalline film as in the related art, but became a ceramic thin film having excellent crystal orientation, and as a result, the electrical characteristics (piezoelectric characteristics) of the obtained film were improved. The same effect was confirmed when a titanium metal layer was formed on a substrate. In this embodiment, an example was described in which attention was paid to the piezoelectric characteristics of a PZT film manufactured by a so-called sol-gel method.
The same effect as that of the present example was confirmed, and it was possible to improve thin film physical properties such as piezoelectricity, pyroelectricity, and ferroelectricity. Regarding the crystallization method, in this example, the case of the most standard heating and firing method was described, but without being limited to this, a method of crystallizing by supplying energy from the outside including laser irradiation is widely and generally used. Anything can be applied, and the effects of the present invention can be obtained.

[0047]

[Table 1]

[0048]

As described above, in forming a titanium-containing ceramic thin film on a substrate, first, a titanium compound layer is formed on a substrate, so that the obtained crystalline film does not become a polycrystalline film. It becomes a titanium-containing ceramic thin film having excellent crystal orientation. As a result, electric characteristics (piezoelectric characteristics) are improved. Therefore, the ceramic thin film obtained by the production method of the present invention can exhibit excellent characteristics when incorporated as a component of a device utilizing its physical properties.

[Brief description of the drawings]

FIG. 1 is a locking curve diagram of a PZT (111) plane of a sample 1 of the present invention.

FIG. 2 is a diagram showing a locking curve of a PZT (111) surface according to a conventional example.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C30B 29/32 C04B 35/49 A

Claims (10)

[Claims] (1) a step of forming a titanium (Ti) compound layer on a substrate; (2) a step of forming an amorphous ceramic precursor film on the titanium compound layer; (3)
A method for producing a titanium-containing ceramic thin film. 2. The method according to claim 1, wherein the titanium (Ti) compound layer formed on the substrate is a metal titanium (Ti) layer. 3. The method according to claim 1, wherein the titanium (Ti) compound layer formed on the substrate is a titanium oxide (TiO2) layer. 4. The method according to claim 1, wherein the titanium (Ti) compound layer formed on the substrate is a lead titanate (PbTiO3) layer. 5. The method for producing a titanium-containing ceramic thin film according to claim 1, wherein the thickness of the titanium (Ti) compound layer formed on the substrate is 10 nm or less. 6. The method according to claim 1, wherein the formation of the amorphous ceramic precursor film is achieved by applying and drying a sol made of an organometallic compound as a raw material. A method for producing a titanium-containing ceramic thin film. 7. A step of forming a titanium (Ti) compound layer on a substrate, and a step of applying and drying a sol containing lead and zirconium and not containing titanium on the titanium compound layer. And (3) a step of applying and drying a sol containing lead, zirconium and titanium by n times (n
Is an integer of 1 or more), and (4) a step of crystallizing the same. 8. A step of (1) forming a titanium (Ti) compound layer on a substrate; and (2) coating and drying a sol containing lead and zirconium and not containing titanium on the titanium compound layer. (3) a step of (3) crystallizing the same, and (4) a step of applying and drying a sol containing lead, zirconium and titanium n times (n is an integer of 1 or more), and (5) A) a step of crystallizing the thin film. 9. The method for producing a titanium-containing ceramic thin film according to claim 7, wherein the titanium (Ti) compound layer formed on the substrate is a metal titanium (Ti) layer. 10. The method for producing a titanium-containing ceramic thin film according to claim 7, wherein the titanium (Ti) compound layer formed on the substrate is a titanium oxide (TiO2) layer.