JPH07211135A - Ferroelectric thin film and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a ferroe1ectric thin film in which high c-axis orientation is given in forming the thin film, and in which performing a polarization process like that in bulk crystals is not required by adding at least one element selected among Mg and Mn to be coupled with oxygen atoms in six-configuration to lead titanate to which La is added, and forming this to be the ferroelectric thin film. CONSTITUTION:An MgO single crystal substrate 9 in which a primer platinum electrode is formed preliminarily in a sputterhing method is installed on a substrate heating heater 10. Air in the inside of a chamber 7 is discharged, the substrate 9 is heated by the substrate heating heater 10, Ar and 02 as sputtering gas is introduced into the chamber 7 by a nozzle 14, and it is kept at a high vacuum degree. High frequancy power is charged from a high frequency power source to a target 1 to generate plasma, so film formation is performed on the substrate 9. A ferroelectric thin film of a composition formula of [(1-x).Pb1-yLayTi1-y/4O3+x.MgO], for example, is thus manufactured, where x=0.01-0.10, y=0.05-0.25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric thin film used for a pyroelectric infrared detecting element, a piezoelectric element and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Ferroelectrics are parallel or
Is the spontaneous polarization caused by antiparallel permanent dipoles.
It exists even without an electric field, and this is countered by an external electric field.
It is a substance that can be turned. This property
The ferroelectric material is used as a pyroelectric infrared detector.
Element, piezoelectric element, optical modulator utilizing electro-optical characteristics, non-volatile
It can be applied to various electronic components such as memory cells.
Perovskite type crystal is used as a typical ferroelectric material.
Structural oxides such as PbTiO₃, Pb_1-XLa _XT
i_{1-X / 4}O₃(PLT), PbZrXTi_1-XO₃(P
ZT), BaTiO ₃Etc. are particularly well known. this
Of which, PbTiO₃Ferroelectrics have a high Curie temperature
Degree, large pyroelectric coefficient, moderately low dielectric constant, and
Promising as a pyroelectric material due to its low dielectric loss
Infrared sensor using ceramic has already been commercialized
Has been done.

This pyroelectric infrared sensor has an advantage that it operates at room temperature and has no wavelength dependence. Also,
Among thermal infrared sensors, it is superior in terms of sensitivity and response speed.

At present, most of the ferroelectric materials used for infrared detection elements and piezoelectric elements are polycrystalline porcelains. However, with the recent miniaturization of electronic parts, electronic materials for ferroelectric materials have been applied. There is a demand for smaller parts. Further, the thinner the pyroelectric element, the lower the heat capacity and the higher the sensitivity. Therefore, the ferroelectric single crystal that achieves high sensitivity and high-speed response is required from the needs of the performance improvement of the infrared detection element and the reduction in size and weight described above. Attention has been paid to the reduction of the film thickness.

For example, c-axis oriented PbTiO 3₃For system thin film
The pyroelectric infrared sensor described in J. Appl. Phy
s. , Vol. 61, P.I. 411 (1987)
Has been. Also, see Japanese Unexamined Patent Publication No. 59-138004.
PbTiO₃La to₂O₃Small amount of
A ferroelectric thin film whose performance index has been improved by
Has been. Also, see Japanese Patent Laid-Open No. 59-141427.
PbTiO ₃To MnO₂For adding a small amount of
Ferroelectric material with improved figure of merit and dielectric loss
Thin films have been proposed. Also, JP-A-61-88403
As seen in Japanese Patent Publication No.₃At Pb /
It has a high electro-optical effect by selecting the Ti molar ratio,
Ferroelectric PbTiO3 with High and Piezoelectricity₃Single phase thin film
Proposed. In addition, JP-A-3-245406
As seen in, PbTiO₃Addition of small amount of MgO to
Ferroelectric with High DC Resistivity and High Pyroelectric Coefficient
Thin films have been proposed.

[0006]

However, in the various thin film forming techniques of PbTiO ₃ based on the prior art as described above, the pyroelectric characteristics, the piezoelectric characteristics, the specific resistance, the withstand voltage and the dielectric loss are as follows. Although improved to some extent, a thin film having satisfactory properties for all has not been obtained yet.

In order to solve the above-mentioned conventional problems, the present invention provides a ferroelectric thin film to which a high c-axis orientation is imparted and which does not require polarization treatment like a bulk crystal, and a manufacturing method thereof. With the goal.

[0008]

In order to achieve the above object, the ferroelectric thin film of the present invention is selected from Mg and Mn which form a hexacoordinate bond with an oxygen atom in lead titanate added with La. It is characterized in that at least one element is added to form a thin film.

In the above structure, the additive element is Mg and the composition of the thin film is [(1-x) .Pb _1-y La _y Ti
_{1-y / 4} O ₃ + x · MgO] (x = 0.01 to 0.10,
It is preferable that y = 0.05 to 0.25). Mg
If the composition range of La and La is less than the above range, the effect of addition is small, and if the composition range of Mg and La exceeds the above range, various properties such as crystallinity and pyroelectric properties tend to be adversely affected. Become.

Further, in the above structure, the additional element is Mn.
And the composition of the thin film is [(1-z) .Pb _1-y La _y T
i _{1-y / 4} O ₃ + z · MnO ₂ ] (y = 0.05 to 0.2
5, z = 0.002 to 0.05) is preferable. When the composition range of Mn and La is less than the above range, the effect of addition is small. On the contrary, when the composition range of Mn and La exceeds the above range, various properties such as crystallinity and pyroelectric properties tend to be adversely affected. Becomes

In the above structure, it is preferable that the crystal phase of the ferroelectric thin film is a single phase of perovskite.
By doing so, particularly high c-axis orientation is imparted,
In addition, it is possible to realize a ferroelectric thin film that does not require polarization treatment like a bulk crystal.

Further, in the above structure, the thickness of the ferroelectric thin film is preferably in the range of 100 nm or more and 10 μm or less. If the thickness of the ferroelectric thin film is less than 100 nm, it is too thin to easily insulate, and if it exceeds 10 μm, the film forming time is long and it is not practical.

In the above structure, it is preferable that the ferroelectric thin film is a thin film that has not been polarized (as-grown thin film). In the conventional method, it is usually necessary to polarize (poling) the pyroelectric material under high temperature and high electric field conditions, but since high temperature and high electric field conditions are used,
The thin film could be altered or decomposed. On the other hand, since the thin film of the present invention does not require polarization treatment, the thin film can be stably held. The as-grown thin film is also called as-deposited thin film.

Further, in the above-mentioned structure, in the X-ray reflection intensity analysis of the ferroelectric thin film, the height (intensity) of the (001) peak is I (001), and the height (intensity) of the I (100) peak is I (100), α = I (001) /
When {I (001) + I (100)}, the orientation ratio α of the ferroelectric thin film is preferably in the range of 0.85 ≦ α ≦ 1.00. Orientation rate α is 0.85 ≦ α ≦
The range of 1.00 indicates that the crystal phase has a high C-axis orientation. In the conventional normal ceramic lead titanate, (101) is the strongest peak and (0)
It cannot be oriented in the (01) direction. In addition, since the C-axis direction is the polarization axis, this thin film has the property of being oriented to the C-axis, so that the polarization treatment (poling treatment) after film formation becomes unnecessary. The method of obtaining the orientation rate α will be described in Example 1 described later. The orientation rate α changes depending on the added amounts of La, Mg and Mn. In the case of Mg and Mn, Mg is x = 0.01 to 0.10 and Mn is z = 0.0.
The range of 02 to 0.05 is preferable, and the maximum orientation ratio α is x = 0.02 to 0.04 for Mg and z = for Mn.
It is in the range of 0.005 to 0.02. On the contrary, Mg is x =
0.01-0.10, Mn is z = 0.002-0.05
Outside the range of, the orientation rate α becomes small. In the case of La, the orientation rate α tends to increase as the amount of the additive decreases.

In the above structure, it is preferable that the dielectric thin film is sandwiched between two layers of electrodes. This is because it is used for an element for a pyroelectric infrared sensor. Further, in the above structure, it is preferable that the ferroelectric thin film is used as a pyroelectric material for a pyroelectric infrared sensor. This is because it is particularly suitable for this application.

Next, the method of manufacturing the ferroelectric thin film of the present invention is as follows.
A method for forming a ferroelectric thin film by adding at least one element selected from Mg and Mn that forms a hexacoordinate bond with oxygen atoms to lead titanate to which La has been added. The inorganic single crystal plate formed by the sputtering method is placed on the substrate heating heater, the chamber is evacuated, the substrate is heated by the substrate heating heater, the sputtering gas is introduced into the chamber, and the target is kept at a high degree of vacuum. It is characterized in that high-frequency power is applied from a high-frequency power source to generate plasma and a film is formed on the substrate. By adopting this method, the ferroelectric thin film of the present invention can be formed efficiently and rationally.

In the above method, the composition of the sputtering target is [(1-w). {(1-x) .P
b _1-y La _y Ti _{1-y / 4} O ₃ + x.MgO} + w.Pb
O] and [(1-w) · {(1-x) (1-y) · P
bO + (1-x) y / 2 · La ₂ O ₃ + (1-x) (1
-Y / 4) ・ TiO ₂ + x ・ MgO} + w ・ PbO]
(X = 0.01-0.10, y = 0.05-0.25,
At least one compound selected from w = 0.05 to 0.40) and the number of targets is preferably 1 or more. This is for forming a thin film having the composition of the present invention.

In the above method, the composition of the sputtering target is [(1-w). {(1-z)
_{· Pb 1-y La y Ti} 1-y / 4 O 3 + z · MnO 2} + w
.PbO], and [(1-w). {(1-z) (1-
y) · PbO + (1-z) y / 2 · La ₂ O ₃ + (1-
z) (1-y / 4) ・ TiO ₂ + z ・ MnO ₂ } + w ・
PbO] (y = 0.05 to 0.25, z = 0.002 to
0.05, w = 0.05 to 0.40), and it is preferable that the number of targets is 1 or more. This is for forming a thin film having the composition of the present invention.

Further, in the above method, sputtering
The target composition of the method is selected from the following (A) to (C)
Use a target consisting of at least one combination
Is preferred. (A) [(1-w) · Pb_1-yLa_yTi_{1-y / 4}O₃+
w · PbO] and [(1-w) · {(1-y) · PbO
+ Y / 2 ・ La₂O₃+ (1-y / 4) ・ TiO ₂} +
w · PbO] (y = 0.05 to 0.25, w = 0.05
~ 0.40) at least one target selected from
And at least one target selected from MgO and Mg
A combination of two types of get. (B) [(1-w) ・ {(1-x) ・ PbTiO 3₃+ X
.MgO} + w.PbO] and [(1-w). {(1-
x) (PbO + TiO₂) + X ・ MgO} + w ・ Pb
O] (x = 0.01-0.10, w = 0.05-0.4
0) at least one target selected from La) and La
₂O₃A combination of two types of targets. (C) [(1-x) Pb_1-yLa_yTi_{1-y / 4}O₃+
x.MgO] and [((1-x) (1-y) .PbO +
(1-x) y / 2 · La₂O₃+ (1-x) (1-y /
4) ・ TiO₂+ X · MgO] (x = 0.01 to 0.1
0, y = 0.05 to 0.25)
Two types of target, one target and PbO target
Matching.

Further, in the above method, sputtering
The target composition of the method is selected from the following (D) to (F)
Use a target consisting of at least one combination
Is preferred. (D) [(1-w) · Pb_1-yLa_yTi_{1-y / 4}O₃+
w · PbO] and [(1-w) · {(1-y) · PbO
+ Y / 2 ・ La₂O₃+ (1-y / 4) ・ TiO ₂} +
w · PbO] (y = 0.05 to 0.25, w = 0.05
~ 0.40) at least one target selected from
And MnO₂And at least one selected from Mn
A combination of two types of target. (E) [(1-w) ・ {(1-z) ・ PbTiO 3₃+ Z
・ MnO₂} + W · PbO] and [(1-w) · {(1
-Z) (PbO + TiO₂) + Z ・ MnO₂} + W ・ P
bO] (z = 0.002-0.05, w = 0.05-
0.40) at least one target selected from
And La₂O₃A combination of two types of targets. (F) [(1-z) · Pb_1-yLa_yTi_{1-y / 4}O₃+
z MnO₂] And [(1-z) (1-y) .PbO +
(1-z) y / 2 · La₂O₃+ (1-z) (1-y /
4) ・ TiO₂+ Z ・ MnO₂] (Y = 0.05-0.
25, z = 0.002-0.05) less
Two types, one target and one PbO target
Combination of.

Further, in the above method, it is preferable to use a target in which the composition of the sputtering target is at least one combination selected from the following (G) to (I). This is for forming a thin film having the composition of the present invention. (G) [(1-w ) · PbTiO 3 + w · PbO] and [(1-w) · ( PbO + TiO 2) + w · PbO]
At least one target selected from (w = 0.05 to 0.40), a La ₂ O ₃ target, and MgO.
And at least one target selected from Mg 3
A combination of types. (H) [Pb _1-y La _y Ti _{1-y / 4} O ₃ ] and [(1-
y) ・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4) ・
TiO ₂ ] (y = 0.05 to 0.25), at least one target, and a PbO target.
Three types of combinations of at least one target selected from MgO and Mg. (I) [(1-x ) · PbTiO 3 + x · MgO] and [(1-x) · ( PbO + TiO 2) + x · MgO]
At least one target selected from (x = 0.01 to 0.10), a La ₂ O ₃ target, and PbO
3 kinds of target combination.

Further, in the above method, it is preferable to use a target having a composition of the sputtering method which is a combination of at least one selected from the following (J) to (L). This is for forming a thin film having the composition of the present invention. (J) [(1-w ) · PbTiO 3 + w · PbO] and [(1-w) · ( PbO + TiO 2) + w · PbO]
At least one target selected from (w = 0.05 to 0.40), a La ₂ O ₃ target, and MnO
3 combinations of at least one target selected from ₂ and Mn. (K) [Pb _1-y La _y Ti _{1-y / 4} O ₃ ] and [(1-
y) ・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4) ・
TiO ₂ ] (y = 0.05 to 0.25), at least one target, and a PbO target.
Three kinds of combinations of at least one target selected from MnO ₂ and Mn. (L) [(1-z ) · PbTiO 3 + z · MnO 2] and [(1-z) · ( PbO + TiO 2) + z · Mn
O ₂ ] (z = 0.002 to 0.05), at least one target, a La ₂ O ₃ target, and a PbO target.

In the above method, the sputtering target is PbTiO ₃ or [PbO + Ti
O ₂ ], a target of La ₂ O ₃ , a target of MgO or Mg, and a target of PbO are preferably used as a plurality of targets. This is for forming a thin film having the composition of the present invention.

In the above method, the sputtering target is PbTiO ₃ or [PbO + Ti
O ₂ ] target, La ₂ O ₃ target, MnO ₂ or Mn target, PbO
It is preferable to use a plurality of targets that are a combination of four types of targets. This is for forming a thin film having the composition of the present invention.

Further, in the above method, when the target of the sputtering method is an oxide, a ceramic or powder is pressed and molded, and when it is a simple substance, it is preferably a metal plate. This is because it is suitable as a material for the sputtering method.

Further, in the above-mentioned method, the conditions of the sputtering method are as follows: the temperature is in the range of 550 to 650 ° C., the pressure is in the range of 0.1 to 2.0 Pa, and the input power is 1.5 to 3. It is preferable that the atmosphere gas is 5 W / cm ² and the atmosphere gas is a mixed gas of argon and oxygen. An example flow rate of a mixed gas of argon and oxygen is Ar: O ₂ = 9:
It is 1 cm ³ / min. The sputter time depends on the required film thickness and sputter rate, but is 15 hours when the sputter rate is 200 nm / h and the film thickness is 3000 nm, for example.

[0027]

According to the structure of the present invention described above, at least one element selected from Mg and Mn that forms a hexacoordinate bond with an oxygen atom is added to lead titanate to which La is added, and a ferroelectric thin film is obtained. By forming a thin film, a high c-axis orientation is imparted when forming a thin film, and it is not necessary to perform polarization treatment unlike a bulk crystal. In addition, the obtained thin film is M that forms a hexacoordinate bond with oxygen atoms in lead titanate containing La.
When at least one element selected from g and Mn is added to form a ferroelectric thin film, Mg and Mn enter the B site, a part of which is vacant by the addition of La, so that the conventional La In comparison with the lead titanate thin film to which is added, the electrical properties of the pyroelectric material such as the relative permittivity εr, the pyroelectric coefficient γ, and the dielectric loss tan δ are excellent. When a plurality of types of targets are used when forming a thin film by the sputtering method, the composition can be controlled by controlling the high-frequency input power of each target.

Now, the perovskite crystal structure of PbTiO ₃ will be described with reference to the drawings. Figure 5 shows PbTi
FIG. 3 is a model diagram showing an oxygen atom octahedron having a perovskite crystal structure of O ₃ . In FIG. 5, the black circle in the center indicates titanium (Ti), the white circle with dots indicates lead (Pb), and the white circle indicates oxygen (O). The position of titanium (Ti) is the B site. Therefore, the B site can also be expressed as "center position of oxygen atom octahedron of perovskite crystal structure". In addition, A site says lead (Pb).

[0029]

The present invention will be described more specifically with reference to the drawings. In FIG. 1, 1 is a target, 2 is a target dish, 3 is a magnet, 4 is a cover that covers the edge of the target dish 2, 5 is a high frequency electrode, 6 is an insulator, 7 is a vacuum chamber, 8 is a high frequency power supply, and 9 is Substrate 10, substrate heater, 11 metal mask, 12 and 13 valves, 14 nozzle for supplying sputter gas into the vacuum chamber 7, 15 motor for rotating substrate heater 10, 32 bearing with seal is there.

The method of manufacturing this ferroelectric thin film is as follows. As shown in FIG. 1, the ferroelectric thin film of this example was produced by a high frequency magnetron sputtering method. First, the target 1 used for sputtering was produced as follows.

The target composition is {(1-x) .Pb_1-y
La_yTi_{1-y / 4}O₃+ X.MgO} (x = 0.01-
0.10, y = 0.05 to 0.25)
O, La₂O₃, TiO₂, Mix MgO powder,
It was calcined at 50 ° C. for 4 hours and then pulverized. Or
{(1-x) (1-y) ・ PbO + (1-x) y / 2 ・
La₂O₃+ (1-x) (1-y / 4) ・ TiO₂+ X
・ PbO, La to become MgO}₂O₃, Ti
O₂, MgO powders were mixed and crushed. These powders
In order to prevent the shortage of Pb,
By further mixing a mol% excess of PbO powder, the composition was
[(1-w) ・ {(1-x) ・ Pb_1-yLa_yTi
_{1-y / 4}O₃+ X · MgO} + w · PbO] or [(1
-W) ・ {(1-x) (1-y) ・ PbO + (1-x)
y / 2 ・ La₂O₃+ (1-x) (1-y / 4) ・ Ti
O₂+ X · MgO} + w · PbO] (x = 0.01 to
0.10, y = 0.05 to 0.25, w = 0.05 to
0.40). 30g of this powder
Fill the target tray 2 and use a hydraulic press to
50 kgf / cm²Molding with the surface pressure of
It was The thinness obtained with the targets produced by these two methods
The membranes showed comparable properties.

The target plate 2 was placed on the magnet 3, and the cover 4 was placed on it. The magnet 3 and the high-frequency electrode 5 below the magnet 3 are insulated from the vacuum chamber 7 by an insulator 6. Further, the high frequency electrode 5 is connected to a high frequency power source 8.

The thin film substrate 9 is a <100> oriented MgO single crystal plate (20 mm × 20 mm, thickness 0.5 m).
m) was used. On one surface of the substrate 9, platinum having a <100> preferential orientation was formed in advance as a base electrode to a thickness of 100 nm by a sputtering method, and patterning was performed. This substrate 9 was placed on the substrate heater 10, and a metal mask 11 made of stainless steel and having a thickness of 0.2 mm was attached to the surface of the substrate 9. Then, the chamber 7 is evacuated, and the substrate 9 is heated by the substrate heater 10.
Was heated to 600 ° C. The substrate heater 10 was rotated by the motor 15. After heating, the valves 12 and 13 were opened, and the sputtering gases Ar and O ₂ were changed to 9:
It was introduced into the chamber 7 from the nozzle 14 at a ratio of 1, and the degree of vacuum was maintained at 0.5 Pa. After that, on target 1,
High frequency power from the high frequency power source 8 is 2.1 W / cm ² (13.
56 MHz) was applied to generate plasma, and a film was formed on the substrate 9. In this way, [(1-x) · Pb
_1-y La _y Ti _{1-y / 4} O ₃ + x · MgO] (x
= 0.01 to 0.10, y = 0.05 to 0.25). The film thickness of the obtained thin film was about 1 μm after the film formation time of 5 hours. On the ferroelectric thin film, a Ni-Cr electrode was formed to a thickness of 50 nm by a DC sputtering method for measurement, and patterned.

For the obtained thin film, the solid capacity of each component is
X-ray microanalyzer, crystal phase and c-axis orientation rate
α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. X-ray diffraction measurement
The sheet is shown in FIG. The measurement range is 20 ° to 50 °
It was In FIG. 3, A is a composition [0.96 (Pb_0.9La
_0.1Ti_0.975O₃) + 0.04MgO] thin film (0
01) peak, B is the same (100) peak, C is MgO single
The peak of the crystal substrate, D is the composition [0.96 (Pb_0.9La
_0.1Ti_0.975O₃) + 0.04MgO] thin film (0
02) peak, E is the same (200) and Pt of the base electrode
The combined peaks are shown respectively.

Next, how to obtain the orientation rate α will be described. In FIG. 3, intensity (height) I of the (001) peak shown in A
The intensity (height) I (100) of (001) and the (100) peak shown in B was measured from the chart, and α = I (00
1) / {I (001) + I (100)}. The thin film shown in FIG. 3 had α = 0.936.

As described above, only (001) and (100) and their higher peaks were confirmed. This allows
When the orientation rate α is obtained, in the as-grown thin film,
In the range of 0.85 ≦ α ≦ 1.00, high c-axis orientation was exhibited. Further, the solid content of MgO is M of the target composition.
It almost coincided with the amount of gO. Moreover, the crystal phase was completely a perovskite single phase.

Next, the pyroelectric coefficient γ, the relative permittivity εr and the dielectric loss tan δ of the obtained thin film were measured. Tables 1 and 2 show the pyroelectric coefficient γ, the relative dielectric constant εr, and the dielectric loss tan δ of the thin films of each composition. Table 2 also shows the value of PbTiO ₃ in bulk.

[0038]

[Table 1]

[0039]

[Table 2]

As is clear from Tables 1 and 2, La
In the sample in which the added amount y of MgO was in the range of 0.05 to 0.25 and the added amount x of MgO was changed to 0.01 to 0.10.
It was confirmed that the pyroelectric coefficient γ was large and the relative permittivity εr and the dielectric loss tan δ were small as compared with the sample of = 0 and the bulk value.

As described above, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
It was confirmed that the material was an extremely excellent ferroelectric thin film material in which the pyroelectric coefficient γ was improved and the relative permittivity εr and the dielectric loss tan δ were decreased as compared with the bulk value of.

Next, FIG. 4 shows a structure in which the ferroelectric thin film of this embodiment is used as a pyroelectric material for a pyroelectric infrared sensor. In FIG. 4, 40 is an element of a pyroelectric infrared sensor, 41 is a 0.5 mm thick MgO single crystal plate, 42
Is a Pt lower electrode having a thickness of 100 nm, 43 is a thickness of 1 μm, and has a composition [0.96 (Pb _0.9 La _0.1 Ti _0.975 O ₃ ) +
0.04MgO] ferroelectric thin film, 44 is 50 nm thick
Is an upper electrode of Ni-Cr. By doing so, it was possible to realize a pyroelectric infrared sensor element (element) to which high c-axis orientation was imparted when forming a thin film, and which did not require polarization treatment like bulk crystals.

Example 2 The ferroelectric thin film of this example is
As shown in FIG. 1, high frequency magnetron sputtering
It was produced by the method. First, the target used for sputtering
Get 1 was manufactured as follows. The target composition is
{(1-z) · Pb_1-yLa_yTi_{1-y / 4}O₃+ Z ・ M
nO ₂} (Y = 0.05-0.25, z = 0.002-
0.05) PbO, La₂O₃, TiO
₂, MnO₂Powders were mixed and calcined at 750 ° C for 4 hours
After that, it was crushed. Alternatively, {(1-z) (1-y) ・
PbO + (1-z) y / 2 ・ La₂O₃+ (1-z)
(1-y / 4) ・ TiO₂+ Z ・ MnO₂} To become
, PbO, La₂O₃, TiO₂, MnO₂Powder of
Mixed and ground. Prevents lack of Pb in these powders
5 to 40 mol% excess of Pb in each case
O powder was further mixed to give a composition of [(1-w) · {(1
-Z) / Pb_1-yLa_yTi_{1-y / 4}O₃+ Z · Mn
O₂} + W · PbO] or [(1-w) · {(1-
z) (1-y) ・ PbO + (1-z) y / 2 ・ La₂O
₃+ (1-z) (1-y / 4) ・ TiO₂+ Z ・ MnO
₂} + W · PbO] (y = 0.05 to 0.25, z =
0.002-0.05, w = 0.05-0.40)
It was to so. Target plate 2
To about 250 kgf / c using a hydraulic press.
m²The target 1 was formed by molding with the surface pressure of. These two
Thin films obtained with targets prepared by the same method are
Showed sex.

The target plate 2 was placed on the magnet 3 and the cover 4 was placed on it. The magnet 3 and the high-frequency electrode 5 below the magnet 3 are insulated from the vacuum chamber 7 by an insulator 6. Further, the high frequency electrode 5 is connected to a high frequency power source 8.

As the thin film substrate 9, a <100> -oriented MgO single crystal plate (20 mm × 20 mm, thickness 0.5 m) was used.
m) was used. On one surface of the substrate 9, platinum having <100> preferential orientation was formed in advance as a base electrode by a sputtering method, and patterning was performed. This substrate 9 is placed on the substrate heater 10 and the surface of the substrate 9 is covered with a metal mask 1 made of stainless steel and having a thickness of 0.2 mm.
I installed 1. Then, the inside of the chamber 7 was evacuated, and the substrate 9 was heated to 600 ° C. by the substrate heater 10. The substrate heater 10 was rotated by the motor 15. After heating, the valves 12 and 13 were opened, and the sputtering gas Ar and O ₂ were mixed at a ratio of 9: 1 to the nozzle 1.
4 was introduced into the chamber 7, and the degree of vacuum was maintained at 0.5 Pa. After that, a high-frequency power of 2.1 W / cm ² (13.56 MHz) was applied to the target 1 from the high-frequency power source 8 to generate plasma and form a film on the substrate 9. In this way, [(1-z) .Pb _1-y La _y Ti
_{1-y / 4} O ₃ + z · MnO ₂ ] (y = 0.05 to
A ferroelectric thin film of 0.25, z = 0.002 to 0.05) was prepared. The film thickness of the obtained thin film was about 0.95 μm after the film formation time of 5 hours. For measurement, a Ni—Cr electrode was formed on the ferroelectric thin film by a DC sputtering method and patterned.

With respect to the obtained thin film, the solid capacity of each component was measured by an X-ray microanalyzer for crystal phase and c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, MgO
The solid capacity was almost the same as the amount of MgO in the target composition. Further, the crystal phase is a completely perovskite single phase, and (00
Only 1) and (100) and their higher peaks were confirmed. Thus, when α is obtained, as-grown
The thin film had a high c-axis orientation in the range of 0.84 ≦ α ≦ 1.00.

Next, the pyroelectric coefficient γ, the relative permittivity εr and the dielectric loss tan δ of the obtained thin film were measured. Tables 3 to 4 show the pyroelectric coefficient γ, the relative permittivity εr, and the dielectric loss tan δ of the thin films of each composition. Table 4 also shows bulk PbTiO ₃ values.

[0048]

[Table 3]

[0049]

[Table 4]

As is clear from Tables 3 to 4, La
In the sample in which the added amount y of MnO ₂ was in the range of 0.05 to 0.25 and the added amount z of MnO ₂ was changed to 0.002 to 0.05, the sample was compared with the sample of z = 0 and the bulk value by γ. Was confirmed to be large and εr and tan δ to be small.

Thus, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

(Embodiment 3) 16 and 1 in FIG.
7 and 18 and 19 are targets, 20 and 21
And 22 and 23 are high frequency power sources, 24 is a vacuum chamber, 25 is a substrate, 26 is a substrate heater, 27 is a metal mask, 28 and 29 are valves, 30 is a nozzle for supplying a sputtering gas into the vacuum chamber 24, and 31 is It is a motor that rotates the substrate heater 26. The cover, electrodes, insulators, magnets, etc. around the target shown in FIG. 1 are omitted.

The method of manufacturing this ferroelectric thin film is as follows. The ferroelectric thin film of the present invention, as shown in FIG.
It was manufactured by a multi-source high frequency magnetron sputtering method with four targets. These four targets are
The heaters are arranged in concentric circles equidistant from the substrate in the center of the heater. As a target used for sputtering,
(Pb, La) TiO ₃ powder target 16 and M
Two types of gO ceramic targets 17 were used.
Of these, a target 16 of (Pb, La) TiO ₃ powder was prepared as follows.

The target composition is Pb _1-y La _y Ti
P to be _{1-y / 4} O ₃ (y = 0.05 to 0.25)
Mix powders of bO, La ₂ O ₃ and TiO ₂ at 750 ° C.
It was calcined for 4 hours and then crushed. Or (1-y)
・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4) ・ Ti
Powders of PbO, La ₂ O ₃ and TiO ₂ were mixed so as to become O ₂ and pulverized. In order to prevent the Pb deficiency, these powders each contain 5-40 mol% excess of Pb.
O powder was further mixed to give a composition of [(1-w) .Pb
_1-y La _y Ti _{1-y / 4} O ₃ + w · PbO] or [(1
-W) ・ {(1-y) ・ PbO + y / 2 ・ La ₂ O ₃ +
(1-y / 4) · TiO 2} + w · PbO] (y = 0.
05 to 0.25, w = 0.05 to 0.40). A target dish was filled with 30 g of the powder, and was molded with a hydraulic press at a surface pressure of about 250 kgf / cm ^{2 to} obtain a target 16. The thin films obtained with the target 16 produced by these two types of methods showed equivalent characteristics. The target 16 and the MgO ceramic target 17 were set in the chamber 24. The targets 16 and 17 are connected to the high frequency power sources 20 and 21, respectively.

On the substrate 25, Mg oriented in <100>
An O single crystal plate (20 mm × 20 mm, thickness 0.5 mm) was used. On one surface of the substrate 25, platinum having <100> preferential orientation was formed in advance as a base electrode by a sputtering method and patterned. This board 2
5 is placed on the substrate heating heater 26, and a metal mask 2 made of stainless steel and having a thickness of 0.2 mm is provided on the surface of the substrate 25.
I attached 7. Then, the chamber 24 is evacuated,
The substrate 25 was heated to 600 ° C. by the substrate heater 26. After heating, the substrate heating heater 26 is rotated by the motor 31, the valves 28 and 29 are opened,
The sputtering gas Ar and O ₂ were introduced into the chamber 24 from the nozzle 30 at a ratio of 9: 1 and the vacuum degree was 0.5 P.
kept at a. After that, high frequency power was applied to the targets 16 and 17 from the high frequency power sources 20 and 21 to generate plasma, and a film was formed on the substrate 25. The high frequency power is fixed at 2.1 W / cm ² (13.56 MHz) in the high frequency power source 20 of the target 16 and 0 W to 1.2 W / cm in the high frequency power source 21 of the target 17.
^The amount of MgO added was controlled by changing the value up to ² (13.56 MHz). In this way
[(1-x) ・ Pb _1-y La _y Ti _{1-y / 4} O ₃ + x ・ M
gO] (x = 0.01 to 0.10, y = 0.0
A ferroelectric thin film of 5 to 0.25) was prepared. The film thickness of the obtained thin film was about 1.2 μm after the film formation time of 5 hours.
For measurement, a Ni—Cr electrode was formed as an upper electrode on the ferroelectric thin film by a DC sputtering method and patterned.

With respect to the obtained thin film, the solid capacity of each element was measured by an X-ray microanalyzer for crystal phase and c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, the crystal phase of the thin film was completely a perovskite single phase, and (001)
Only (100) and its higher peaks were confirmed. As a result, when α was determined, the as-grown thin film was in the range of 0.84 ≦ α ≦ 0.96 and showed a high c-axis orientation.

Next, the pyroelectric coefficient γ, the relative permittivity εr and the dielectric loss tan δ of the obtained thin film were measured between the base electrode and the upper electrode. Tables 5 to 6 show the pyroelectric coefficient γ, the relative dielectric constant εr, and the dielectric loss tan δ of the thin films of each composition. Table 6 also shows bulk PbTiO ₃ values.

[0058]

[Table 5]

[0059]

[Table 6]

As is clear from Tables 5 to 6, La
In the sample in which the added amount y of MgO was in the range of 0.05 to 0.25 and the added amount x of MgO was changed to 0.01 to 0.10.
Γ is larger than that of the sample of = 0 and the bulk value,
It was confirmed that r and tan δ were small.

Thus, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

Although a MgO ceramic target was used as the target for sputtering in this example, a metal Mg target was used instead.
It was confirmed that similar results were obtained even when the sputtering gas Ar and O ₂ were introduced into the chamber at a ratio of 9: 3. Further, as a target used for the sputtering of this example, [(1-w) .Pb _1-y La _y Ti was used.
_{1-y / 4} O ₃ + w · PbO] or [(1-w) · {(1
-Y) ・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4)
_{· TiO 2} + w · PbO} ] (y = 0.05~0.2
5, w = 0.05 to 0.40), and M
While using two kinds of gO targets, in addition to the combination, [(1-w) · {(1-x) · PbTiO 3 +
x.MgO} + w.PbO] or [(1-w).
{(1-x) (PbO + TiO 2) + x · MgO} + w
PbO] (x = 0.01 to 0.10, w = 0.05 to
0.40) target and a target that is La ₂ O ₃ , two types of targets and [(1-x) .Pb
_{1-y La y Ti 1-} y / 4 O 3 + x · MgO] or [((1-x) ( 1-y) · PbO + (1-x) y / 2
・ La ₂ O ₃ + (1-x) (1-y / 4) ・ TiO ₂ +
x.MgO] (x = 0.01 to 0.10, y = 0.05
It was confirmed that similar results could be obtained even when a combination of two types of targets, ie, a target of ˜0.25) and a target of PbO.

Example 4 As shown in FIG. 2, the ferroelectric thin film of the present invention was prepared by the multi-source high frequency magnetron sputtering method with four targets. These four targets are arranged on concentric circles equidistant from the substrate centered on the heater. As a target used for sputtering, two types of targets, a powder target 16 of (Pb, La) TiO ₃ and a ceramic target 17 of MnO ₂ were used. Of these, (Pb, La) TiO ₃
The powder target 16 was prepared as follows.

The target composition is Pb _1-y La _y Ti
P to be _{1-y / 4} O ₃ (y = 0.05 to 0.25)
Mix powders of bO, La ₂ O ₃ and TiO ₂ at 750 ° C.
It was calcined for 4 hours and then crushed. Or (1-y)
・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4) ・ Ti
Powders of PbO, La ₂ O ₃ and TiO ₂ were mixed so as to become O ₂ and pulverized. In order to prevent the Pb deficiency, these powders each contain 5-40 mol% excess of Pb.
O powder was further mixed to give a composition of [(1-w) .Pb
_1-y La _y Ti _{1-y / 4} O ₃ + w · PbO] or [(1
-W) ・ {(1-y) ・ PbO + y / 2 ・ La ₂ O ₃ +
(1-y / 4) · TiO 2} + w · PbO] (y = 0.
05 to 0.25, w = 0.05 to 0.40). A target dish was filled with 30 g of the powder, and was molded with a hydraulic press at a surface pressure of about 250 kgf / cm ^{2 to} obtain a target 16. The thin films obtained with the target 16 produced by these two types of methods showed equivalent characteristics. This target 16 and a MnO ₂ ceramic target 17 were set in a chamber 24.
The targets 16 and 17 are connected to the high frequency power sources 20 and 21, respectively.

On the substrate 25, Mg oriented in <100>
O single crystal plate (20 mm × 20 mm, thickness 0.5 mm)
Using. On one surface of the substrate 25, a base electrode is previously formed.
As a result, platinum preferentially oriented in <100> is sputtered.
It was formed by patterning method and patterned. This board 2
5 is placed on the substrate heating heater 26, and the surface of the substrate 25 is
On the surface, a metal mask 2 made of stainless steel with a thickness of 0.2 mm
I attached 7. Then, the chamber 24 is evacuated,
The substrate heating heater 26 heats the substrate 25 to 600 ° C.
Heated at. After heating, motor the substrate heater 26
Rotating by 31, opening valves 28 and 29,
Sputtering gas Ar and O₂Nozzle at a ratio of 9: 1
It is introduced into the chamber 24 from 30 and the degree of vacuum is 0.5P.
kept at a. Then, on targets 16 and 17,
High frequency power is supplied from the frequency power supplies 20 and 21, and the
Zuma was generated and a film was formed on the substrate 25. In addition, high
As for the frequency input power, the high frequency power source 20 of the target 16
2.1 W / cm²Fix at (13.56MHz),
The high frequency power supply 21 of the Get 17 is 0 W to 0.7 W / cm
²Change to any value up to (13.56MHz)
Due to MnO₂The amount added was controlled. Like this
, [(1-z) · Pb_1-yLa_yTi_{1-y / 4}O ₃+ Z
・ MnO₂] Composition (y = 0.05-0.25, z =
A ferroelectric thin film of 0.002 to 0.05) was prepared. Profit
The thickness of the obtained thin film is about 1.15 μm in 5 hours.
Met. On top of the ferroelectric thin film, for measurement
Ni-Cr electrode as a partial electrode by DC sputtering method
Then, it was formed and patterned.

With respect to the obtained thin film, the solid capacity of each element was measured by an X-ray microanalyzer for the crystal phase and the c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, the crystal phase of the thin film was completely a perovskite single phase, and (001)
Only (100) and its higher peaks were confirmed. As a result, when α was determined, the as-grown thin film was in the range of 0.85 ≦ α ≦ 0.96 and showed high c-axis orientation.

Next, the pyroelectric coefficient γ, the relative permittivity εr and the dielectric loss tan δ of the obtained thin film were measured between the base electrode and the upper electrode. Tables 7 to 8 show the pyroelectric coefficient γ, the relative permittivity εr, and the dielectric loss tan δ of the thin films of each composition. Table 8 also shows bulk PbTiO ₃ values.

[0068]

[Table 7]

[0069]

[Table 8]

As is clear from Tables 7 to 8, La
In the sample in which the added amount y of MnO ₂ was in the range of 0.05 to 0.25 and the added amount z of MnO ₂ was changed to 0.002 to 0.05, the sample was compared with the sample of z = 0 and the bulk value by γ. Was confirmed to be large and εr and tan δ to be small.

Thus, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

Incidentally, it is used for the sputtering of this embodiment.
As a target, MnO₂Ceramic target
However, instead of this, a metal Mn target was used.
Sputter gas Ar and O₂At a ratio of 9: 3
Similar results can be obtained when installed in the chamber
It was confirmed. Furthermore, in the sputtering of this embodiment
The target used is [(1-w) .Pb_1-yLa
_yTi_{1-y / 4}O₃+ W · PbO] or [(1-w) ・
{(1-y) ・ PbO + y / 2 ・ La₂O₃+ (1-y
/ 4) ・ TiO₂} + W · PbO] (y = 0.05-
0.25, w = 0.05-0.40)
And MnO₂Two types of targets that are
In addition to this combination, [(1-w).
{(1-z) ・ PbTiO₃+ Z ・ MnO₂} + W ・ P
bO] or [(1-w) · {(1-z) (PbO + T
iO₂) + Z ・ MnO₂} + W · PbO] (z = 0.0
02-0.05, w = 0.05-0.40)
Get and La₂O₃Two types of target
Target and [(1-z) Pb_1-yLa_yTi_{1-y / 4}
O ₃+ Z ・ MnO₂] Or [(1-z) (1-y).
PbO + (1-z) y / 2 ・ La₂O₃+ (1-z)
(1-y / 4) ・ TiO₂+ Z ・ MnO₂] (Y = 0.
05-0.25, z = 0.002-0.05)
Target and PbO target, two types of targets
Similar results are obtained even when using a combination of get
Was confirmed.

Example 5 A ferroelectric thin film was prepared using the same multi-source high frequency magnetron sputtering apparatus as in Example 3. As a target used for this sputtering, a powder target 16 of [PbTiO ₃ + PbO] and a ceramic target 17 of La ₂ O ₃ are used.
And three types of targets 18 made of MgO ceramics were used. Of these, the target 16 of (PbTiO ₃ + PbO) powder has a composition of [(1-w) · PbTiO ₃
+ W · PbO] or [(1-w) · (PbO + TiO 2
₂ ) + w · PbO] (w = 0.05 to 0.40), and the method for producing this target 16 is the same as in Examples 1 to 4.

These three types of targets 16 and 17
And 18 are installed in the chamber and platinum is
The same as in Examples 1 to 4 on the MgO single crystal substrate 25 that has been polished.
The film was formed by the above method. However, high frequency to each target
Wave input power is [PbTiO 3 ₃+ PbO] powder
Target 16 is 2.1 W / cm²(13.56
MHz), and La₂O₃Ceramic target
To 17 is 0 W to 0.7 W / cm²(13.56MH
zO) to any value up to MgO ceramic target
18 is from 0W to 1.2W / cm²(13.56MHz)
Up to an arbitrary value up to La₂O₃And of MgO
The amount added was controlled. In this way, [(1-x) · P
b_1-yLa_yTi_{1-y / 4}O₃+ X · MgO] composition
(X = 0.01-0.10, y = 0.05-0.25)
A ferroelectric thin film was prepared. The film thickness of the obtained thin film is
The film thickness was about 1.3 μm after 5 hours. Its ferroelectric thin
On top of the film, a Ni-Cr electrode was used as an upper electrode for the measurement.
Pole is formed by DC sputtering method and patterned
I went.

With respect to the obtained thin film, the solid capacity of each element was measured by an X-ray microanalyzer with the crystal phase and the c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, the crystal phase of the thin film was completely a perovskite single phase, and (001)
Only (100) and its higher peaks were confirmed. As a result, when α was determined, the as-grown thin film was in the range of 0.85 ≦ α ≦ 0.94 and showed high c-axis orientation.

Next, the pyroelectric coefficient γ, the relative dielectric constant εr and the dielectric loss tan δ of the obtained thin film were measured between the base electrode and the upper electrode. Tables 9 to 10 show the pyroelectric coefficient γ, the relative permittivity εr, and the dielectric loss tan δ of the thin films of each composition. Table 1
The value of bulk PbTiO ₃ is also shown in 0.

[0077]

[Table 9]

[0078]

[Table 10]

As is clear from Tables 9 to 10, L
In the sample in which the addition amount y of a is in the range of 0.05 to 0.25 and the addition amount x of MgO is changed to 0.01 to 0.10.
γ is large compared to the sample of x = 0 and the bulk value,
It was confirmed that εr and tan δ were small.

As described above, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

Although a MgO ceramic target was used as the target for sputtering in this example, a metal Mg target was used instead.
It was confirmed that similar results were obtained even when the sputtering gas Ar and O ₂ were introduced into the chamber at a ratio of 9: 3. Further, as a target used for the sputtering of this example, [(1-w) .PbTiO ₃ + w
· PbO] or [(1-w) · ( PbO + TiO 2)
+ W · PbO] (w = 0.05 to 0.40), a target that is La ₂ O ₃ , and a target that is MgO, three types of targets were used. Pb _1-y La _y Ti _{1-y / 4} O ₃ ]
Or [(1-y) · PbO + y / 2 · La ₂ O ₃ +
(1-y / 4) · TiO ₂ ] (y = 0.05 to 0.2
5) the target, which is PbO, and
Three types of targets, which are targets that are MgO or metallic Mg, and [(1-x) .PbTiO ₃ + x.Mg
O] or [(1-x) · ( PbO + TiO 2) + x ·
Similar results can be obtained even when a combination of three types of targets of MgO] (x = 0.01 to 0.10), La ₂ O ₃ target, and PbO target is combined. It was confirmed.

Example 6 A ferroelectric thin film was prepared using the same multi-source high frequency magnetron sputtering device as in Example 4. As a target used for this sputtering, a powder target 16 of [PbTiO ₃ + PbO] and a ceramic target 17 of La ₂ O ₃ are used.
And three types of MnO ₂ ceramic targets 18 were used. Of these, the target 16 of (PbTiO ₃ + PbO) powder has a composition of [(1-w) · PbTiO 3
₃ + w · PbO] or [(1-w) · (PbO + Ti
O ₂ ) + w · PbO] (w = 0.05 to 0.40), and the method for producing this target 16 is the same as in Examples 1 to 4.

These three types of targets 16 and 17
And 18 are installed in the chamber and platinum is
The same as in Examples 1 to 4 on the MgO single crystal substrate 25 that has been polished.
The film was formed by the above method. However, high frequency to each target
Wave input power is [PbTiO 3 ₃+ PbO] powder
Target 16 is 2.1 W / cm²(13.56
MHz), and La₂O₃Ceramic target
To 17 is from 0W to 1.7W / cm²(13.56MH
z) to any value, MnO₂Ceramic target
18 to 0 W to 0.7 W / cm²(13.56MH
z) to an arbitrary value and La₂O₃And Mn
O₂The amount added was controlled. In this way, [(1-
z) ・ Pb_1-yLa_yTi_{1-y / 4}O₃+ Z ・ MnO₂]
Composition (y = 0.05 to 0.25, z = 0.002 to
0.05) ferroelectric thin film was prepared. Of the obtained thin film
The film thickness was about 1.26 μm after the film formation time of 5 hours. So
As an upper electrode for measurement, on the ferroelectric thin film of
The Ni-Cr electrode is formed by the DC sputtering method,
Patterning was performed.

With respect to the obtained thin film, the solid capacity of each element was measured by an X-ray microanalyzer for the crystal phase and the c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, the crystal phase of the thin film was completely a perovskite single phase, and (001)
Only (100) and its higher peaks were confirmed. As a result, when α was determined, the as-grown thin film was in the range of 0.86 ≦ α ≦ 0.94 and showed high c-axis orientation.

Next, the pyroelectric coefficient γ, the relative permittivity εr and the dielectric loss tan δ of the obtained thin film were measured between the base electrode and the upper electrode. Tables 11 to 12 show the pyroelectric coefficient γ, the relative dielectric constant εr, and the dielectric loss tan δ of the thin films of each composition. Table 1
The value of bulk PbTiO ₃ is also shown in 2.

[0086]

[Table 11]

[0087]

[Table 12]

As is clear from Tables 11 to 12,
When the amount y of La added is in the range of 0.05 to 0.25, MnO
_It was confirmed that in the sample in which the added amount z of 2 was changed from 0.002 to 0.05, γ was larger and εr and tan δ were smaller than those of the sample of z = 0 and the bulk value.

Thus, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

Incidentally, it is used for the sputtering of this embodiment.
As a target, MnO₂Ceramic target
However, instead of this, a metal Mn target was used.
Sputter gas Ar and O₂At a ratio of 9: 3
Similar results can be obtained when installed in the chamber
It was confirmed. Furthermore, in the sputtering of this embodiment
As a target to be used, [(1-w) .PbTiO 3₃
+ W · PbO] or [(1-w) · (PbO + TiO 2
₂) + W · PbO] (w = 0.05 to 0.40)
Target and La₂O₃Target and MnO
₂3 types of targets, which are
However, in addition to this combination, [Pb_1-yLa _yTi
_{1-y / 4}O₃] Or [(1-y) · PbO + y / 2 · L
a₂O₃+ (1-y / 4) ・ TiO₂] (Y = 0.05
~ 0.25) target and PbO target
And MnO₂Or of a target that is metallic Mn,
Three types of targets and [(1-z) ・ PbTiO 3₃+
z MnO₂] Or [(1-z) ・ (PbO + TiO 2
₂) + Z ・ MnO₂] (Z = 0.002-0.05)
A target and La₂O₃Target and P
Combination of three types of targets that are bO
Confirm that the same result can be obtained even if it is mixed
did.

Example 7 Using the same multi-source high frequency magnetron sputtering device as in Example 3, a ferroelectric thin film was prepared. As a target used for this sputtering, a PbTiO ₃ powder target 16 and La were used.
Four kinds of targets, that is, a ₂ O ₃ ceramic target 17, a MgO ceramic target 18, and a PbO ceramic target 19 were used. Of these, PbTiO
The powder target 16 of ₃ has a composition of [PbTiO ₃ ].
Alternatively, it is [PbO + TiO ₂ ], and the method for producing this target is the same as in Examples 1-6.

These four types of targets 16 and 17
And 18 and 19 are installed in chamber 24 and
Implemented on MgO single crystal substrate 25 with gold patterning
Film formation was performed by the same method as in Examples 1 to 4. However, each
The high-frequency input power to the get is PbTiO₃Of powder
The target 16 is 2.1 W / cm²(13.5
6MHz), and La₂O₃Ceramic target
0 to 0.7 W / cm²(13.56MH
zO) to any value up to MgO ceramic target
18 is from 0W to 1.2W / cm²(13.56MHz)
Up to any value, PbO ceramic target 19
Is 0 W to 0.5 W / cm²Up to (13.56MHz)
Change to any value and₂O₃And MgO addition
The amount was controlled to fill the shortage of Pb. Like this
, [(1-x) · Pb_1-yLa _yTi_{1-y / 4}O₃+ X
.MgO] composition (x = 0.01 to 0.10, y =
A ferroelectric thin film of 0.05 to 0.25) was prepared. Got
The thickness of the formed thin film is about 1.4 μm after the film formation time of 5 hours.
It was. On top of the ferroelectric thin film, a top electrode is
Ni-Cr electrode as the electrode by DC sputtering method
It was formed and patterned.

With respect to the obtained thin film, the solid capacity of each element was measured by an X-ray microanalyzer for the crystal phase and the c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, the crystal phase of the thin film was completely a perovskite single phase, and (001)
Only (100) and its higher peaks were confirmed. As a result, when α was determined, the as-grown thin film was in the range of 0.83 ≦ α ≦ 1.00 and showed a high c-axis orientation.

Next, the pyroelectric coefficient γ, relative permittivity εr and dielectric loss tan δ of the obtained thin film were measured between the base electrode and the upper electrode. Tables 13 to 14 show the pyroelectric coefficient γ, the relative dielectric constant εr, and the dielectric loss tan δ of the thin films of each composition. Table 14 also shows bulk PbTiO ₃ values.

[0095]

[Table 13]

[0096]

[Table 14]

As is clear from Tables 13 to 14,
When the amount y of La added is in the range of 0.05 to 0.25, MgO
It was confirmed that γ was large and εr and tan δ were small in the sample in which the addition amount x of was changed from 0.01 to 0.10.

Thus, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

Although a MgO ceramic target was used as the target for sputtering in this example, a metal Mg target was used instead.
It was confirmed that similar results were obtained even when the sputtering gas Ar and O ₂ were introduced into the chamber at a ratio of 9: 3.

Example 8 Using the same multi-source high frequency magnetron sputtering apparatus as in Example 4, a ferroelectric thin film was prepared. As a target used for this sputtering, a PbTiO ₃ powder target 16 and La were used.
Four types of targets were used: a ₂ O ₃ ceramic target 17, a MnO ₂ ceramic target 18, and a PbO ceramic target 19. Of these, PbTi
The target 16 of O ₃ powder has a composition of [PbTi
O _3] or a [PbO + TiO _2], a method for manufacturing the target is the same as in Example 1-6.

These four types of targets 16 and 17
And 18 and 19 were placed in the chamber 24, and a film was formed on the platinum-patterned MgO single crystal substrate 25 by the same method as in Examples 1-6. However, the high-frequency power applied to each target was 2.1 W / cm ² (13.5 W) for the target 16 obtained by pressing the PbTiO ₃ powder.
6 MHz) and the La ₂ O ₃ ceramic target 17 is 0 W to 0.7 W / cm ² (13.56 MH).
z), the MnO ₂ ceramic target 18 has a value of 0 W to 0.7 W / cm ² (13.56 MH).
z), the PbO ceramic target 19 can be set to any value up to 0 W to 0.5 W / cm ² (13.56 MHz).
Up to an arbitrary value up to La ₂ O ₃ and MnO ₂
The amount of Pb added was controlled to fill the shortage of Pb. In this way, [(1-z) .Pb _1-y La _y Ti _{1-y / 4} O
₃ + z · MnO ₂ ] (y = 0.05 to 0.2
5, z = 0.002 to 0.05) to prepare a ferroelectric thin film. The film thickness of the obtained thin film was about 1.
It was 38 μm. For measurement, a Ni—Cr electrode was formed as an upper electrode on the ferroelectric thin film by a DC sputtering method and patterned.

With respect to the obtained thin film, the solid capacity of each element was measured by an X-ray microanalyzer for the crystal phase and the c-axis orientation rate α (= I (001) / {I (001) + I (10
0)}) was measured with an X-ray diffractometer. As a result, the crystal phase of the thin film was completely a perovskite single phase, and (001)
Only (100) and its higher peaks were confirmed. As a result, when α was determined, the as-grown thin film was in the range of 0.84 ≦ α ≦ 0.94 and showed high c-axis orientation.

Next, the pyroelectric coefficient γ, the relative permittivity εr and the dielectric loss tan δ of the obtained thin film were measured between the base electrode and the upper electrode. Tables 15 to 16 show the pyroelectric coefficient γ, the relative permittivity εr, and the dielectric loss tan δ of the thin films of each composition. Table 16 also shows bulk PbTiO ₃ values.

[0104]

[Table 15]

[0105]

[Table 16]

As is clear from Tables 15 to 16,
When the amount y of La added is in the range of 0.05 to 0.25, MnO
_It was confirmed that in the sample in which the added amount z of 2 was changed from 0.002 to 0.05, γ was larger and εr and tan δ were smaller than those of the sample of z = 0 and the bulk value.

Thus, the thin film having the composition of the present invention is
Thin films having compositions outside the scope of the present invention as well as conventional PbTiO ₃
Γ is improved, and εr and tan are increased as compared with the bulk value of
It is an extremely excellent ferroelectric thin film material with a decreased δ.

Although a MnO ₂ ceramic target was used as the target for sputtering in this embodiment, a metal Mn target was used instead, and the sputtering gases Ar and O ₂ were mixed at a ratio of 9: 3. It was confirmed that similar results were obtained even when introduced into the chamber by.

In these Examples 1 to 8, a target obtained by pressing powder into a target and molding was used. However, it was confirmed that similar results could be obtained even when a target of ceramic having the same composition was used. .

[0110]

As described above, the ferroelectric thin film produced by the method for producing a ferroelectric thin film of the present invention is imparted with a high c-axis orientation at the time of forming a thin film, and is polarized like a bulk crystal. Since the thin film obtained by adding at least one element selected from Mg and Mn forming a hexacoordinate bond with an oxygen atom to form a ferroelectric thin film, As a result, Mg and / or Mn enter the B site where some of them are vacant.
Compared with the lead titanate thin film added with a, the relative permittivity ε
It has excellent electrical characteristics as a pyroelectric material such as r, pyroelectric coefficient γ, and dielectric loss tan δ. When a plurality of types of targets are used when forming a thin film by the sputtering method, the composition can be controlled by controlling the high-frequency input power of each target. Therefore, as a pyroelectric sensor material that enables downsizing of devices, high sensitivity, and high-speed response, it is useful to provide a ferroelectric thin film having a very high industrial value and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus for manufacturing a ferroelectric thin film used in an embodiment of the present invention.

FIG. 2 is a schematic diagram of an apparatus for manufacturing a ferroelectric thin film used in an embodiment of the present invention.

FIG. 3 is an X-ray diffraction measurement chart of the ferroelectric thin film of Example 1 of the present invention.

FIG. 4 is a schematic sectional view of a pyroelectric infrared sensor element (element) using the ferroelectric thin film of Example 1 of the present invention.

FIG. 5 is a model diagram showing an oxygen atom octahedron of the perovskite crystal structure of PbTiO ₃ .

[Explanation of symbols]

1 Target 2 Target Dish 3 Magnet 4 Cover 5 High Frequency Electrode 6 Insulator 7 Vacuum Chamber 8 High Frequency Power Supply 9 Substrate 10 Substrate Heating Heater 11 Metal Mask 12 Valve 13 Valve 14 Nozzle 15 Motor 16 Target 17 Target 18 Target 19 Target 20 High Frequency Power Supply 21 High frequency power supply 22 High frequency power supply 23 High frequency power supply 24 Vacuum chamber 25 Substrate 26 Substrate heating heater 27 Metal mask 28 Valve 29 Valve 30 Nozzle 31 Motor 32 Sealed bearing 40 Pyroelectric infrared sensor element 41 Single crystal plate 42 Pt Lower electrode 43 Composition [0.96 (Pb _0.9 La _0.1 Ti _0.975 O
₃ ) + 0.04MgO] ferroelectric thin film 44 Ni-Cr upper electrode

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI Technical indication H01B 3/12 319 H01L 37/02 41/24 (72) Inventor Ryoichi Takayama Osaka Prefecture Kadoma City Kadoma 1006 Matsushita Electric Industrial Co., Ltd. (72) Inventor Masafumi Kobune 10-20 Satsuki-cho, Ako-shi, Hyogo Prefecture (72) Inventor Tomo Fujii 3-1-1 Kitashione, Ako-shi, Hyogo Prefecture

Claims (20)

[Claims] 1. A ferroelectric material comprising a lead-titanate to which La is added, and at least one element selected from Mg and Mn that forms a hexacoordinate bond with an oxygen atom is added to form a thin film. Thin film. Wherein the additional element is Mg, the composition of the thin film _{[(1-x) · Pb 1} -y La y Ti 1-y / 4 O 3 + x · M
gO] (x = 0.01-0.10, y = 0.05-0.
25) The ferroelectric thin film according to claim 1. 3. The additive element is Mn, and the composition of the thin film is [(1-z) · Pb _1-y La _y Ti _{1-y / 4} O ₃ + z · M.
nO ₂ ] (y = 0.05 to 0.25, z = 0.002 to
0.05) The ferroelectric thin film according to claim 1. 4. The ferroelectric thin film according to claim 1, wherein the crystal phase of the ferroelectric thin film is a berovskite single phase. 5. The ferroelectric thin film according to claim 1, wherein the thickness of the ferroelectric thin film is in the range of 100 nm or more and 10 μm or less. 6. The ferroelectric thin film according to claim 1, wherein the ferroelectric thin film is a thin film that has not been polarized (as-grown thin film). 7. In the X-ray reflection intensity analysis of a ferroelectric thin film, the height (strength) of the (001) peak is I (001), and the height (strength) of the I (100) peak is I (100).
And α = I (001) / {I (001) + I (10
0)}, the orientation ratio α of the ferroelectric thin film is
The ferroelectric thin film according to claim 1, which is in a range of 0.85 ≦ α ≦ 1.00. 8. The ferroelectric thin film according to claim 1, which has a structure in which the ferroelectric thin film is sandwiched between two layers of electrodes. 9. The ferroelectric thin film according to claim 8, wherein the ferroelectric thin film is used as a pyroelectric material for a pyroelectric infrared sensor. 10. A method for forming a ferroelectric thin film by adding at least one element selected from Mg and Mn that forms a hexacoordinate bond to an oxygen atom to lead titanate containing La. An inorganic single crystal plate with an underlying platinum electrode formed in advance by a sputtering method is placed on a substrate heating heater, the inside of the chamber is evacuated, the substrate is heated by the substrate heating heater, the sputtering gas is introduced into the chamber, and a high degree of vacuum is set. And a high frequency power is applied to the target from a high frequency power source to generate plasma to form a film on the substrate. 11. The composition of a sputtering target is [(1-w). {(1-x) .Pb _1-y La _y Ti].
_{1-y / 4} O ₃ + x · MgO} + w · PbO], and [(1
-W) ・ {(1-x) (1-y) ・ PbO + (1-x)
y / 2 ・ La ₂ O ₃ + (1-x) (1-y / 4) ・ Ti
O ₂ + x · MgO} + w · PbO] (x = 0.01 to
0.10, y = 0.05 to 0.25, w = 0.05 to
The method for producing a ferroelectric thin film according to claim 10, wherein the ferroelectric thin film is at least one compound selected from 0.40) and the target number is 1 or more. 12. The composition of a sputtering target.
Is [(1-w) ・ {(1-z) ・ Pb_1-yLa_yTi
_{1-y / 4}O₃+ Z ・ MnO₂} + W · PbO], and
[(1-w) ・ {(1-z) (1-y) ・ PbO + (1
-Z) y / 2 · La ₂O₃+ (1-z) (1-y / 4)
・ TiO₂+ Z ・ MnO₂} + W · PbO] (y = 0.
05-0.25, z = 0.002-0.05, w = 0.
05-0.40) at least one compound selected from
And the number of targets is 1 or more.
A method for producing a ferroelectric thin film as described in 1. 13. Composition of sputtering target
Is at least one set selected from the following (A) to (C)
11. The use of a target composed of a mixture, according to claim 10.
Method for manufacturing ferroelectric thin film of. (A) [(1-w) · Pb_1-yLa_yTi_{1-y / 4}O₃+
w · PbO] and [(1-w) · {(1-y) · PbO
+ Y / 2 ・ La₂O₃+ (1-y / 4) ・ TiO ₂} +
w · PbO] (y = 0.05 to 0.25, w = 0.05
~ 0.40) at least one target selected from
And at least one target selected from MgO and Mg
A combination of two types of get. (B) [(1-w) ・ {(1-x) ・ PbTiO 3₃+ X
.MgO} + w.PbO] and [(1-w). {(1-
x) (PbO + TiO₂) + X ・ MgO} + w ・ Pb
O] (x = 0.01-0.10, w = 0.05-0.4
0) at least one target selected from La) and La
₂O₃A combination of two types of targets. (C) [(1-x) Pb_1-yLa_yTi_{1-y / 4}O₃+
x.MgO] and [((1-x) (1-y) .PbO +
(1-x) y / 2 · La₂O₃+ (1-x) (1-y /
4) ・ TiO₂+ X · MgO] (x = 0.01 to 0.1
0, y = 0.05 to 0.25)
Two types of target, one target and PbO target
Matching. 14. Composition of sputtering target
Is at least one selected from the following (D) to (F)
The method according to claim 10, wherein a target composed of a combination is used.
Manufacturing method of the above-mentioned ferroelectric thin film. (D) [(1-w) · Pb_1-yLa_yTi_{1-y / 4}O₃+
w · PbO] and [(1-w) · {(1-y) · PbO
+ Y / 2 ・ La₂O₃+ (1-y / 4) ・ TiO ₂} +
w · PbO] (y = 0.05 to 0.25, w = 0.05
~ 0.40) at least one target selected from
And MnO₂And at least one selected from Mn
A combination of two types of target. (E) [(1-w) ・ {(1-z) ・ PbTiO 3₃+ Z
・ MnO₂} + W · PbO] and [(1-w) · {(1
-Z) (PbO + TiO₂) + Z ・ MnO₂} + W ・ P
bO] (z = 0.002-0.05, w = 0.05-
0.40) at least one target selected from
And La₂O₃A combination of two types of targets. (F) [(1-z) · Pb_1-yLa_yTi_{1-y / 4}O₃+
z MnO₂] And [(1-z) (1-y) .PbO +
(1-z) y / 2 · La₂O₃+ (1-z) (1-y /
4) ・ TiO₂+ Z ・ MnO₂] (Y = 0.05-0.
25, z = 0.002-0.05) less
Two types, one target and one PbO target
Combination of. 15. The method for producing a ferroelectric thin film according to claim 10, wherein the target of the sputtering method is a combination of at least one selected from the following (G) to (I). (G) [(1-w ) · PbTiO 3 + w · PbO] and [(1-w) · ( PbO + TiO 2) + w · PbO]
At least one target selected from (w = 0.05 to 0.40), a La ₂ O ₃ target, and MgO.
And at least one target selected from Mg 3
A combination of types. (H) [Pb _1-y La _y Ti _{1-y / 4} O ₃ ] and [(1-
y) ・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4) ・
TiO ₂ ] (y = 0.05 to 0.25), at least one target, and a PbO target.
Three types of combinations of at least one target selected from MgO and Mg. (I) [(1-x ) · PbTiO 3 + x · MgO] and [(1-x) · ( PbO + TiO 2) + x · MgO]
At least one target selected from (x = 0.01 to 0.10), a La ₂ O ₃ target, and PbO
3 kinds of target combination. 16. The method for producing a ferroelectric thin film according to claim 10, wherein the target of the sputtering method is a combination of at least one selected from the following (J) to (L). (J) [(1-w ) · PbTiO 3 + w · PbO] and [(1-w) · ( PbO + TiO 2) + w · PbO]
At least one target selected from (w = 0.05 to 0.40), a La ₂ O ₃ target, and MnO
3 combinations of at least one target selected from ₂ and Mn. (K) [Pb _1-y La _y Ti _{1-y / 4} O ₃ ] and [(1-
y) ・ PbO + y / 2 ・ La ₂ O ₃ + (1-y / 4) ・
TiO ₂ ] (y = 0.05 to 0.25), at least one target, and a PbO target.
Three kinds of combinations of at least one target selected from MnO ₂ and Mn. (L) [(1-z ) · PbTiO 3 + z · MnO 2] and [(1-z) · ( PbO + TiO 2) + z · Mn
O ₂ ] (z = 0.002 to 0.05), at least one target, a La ₂ O ₃ target, and a PbO target. 17. The target of the sputtering method is P
bTiO ₃ or [PbO + TiO ₂ ] target, La ₂ O ₃ target, MgO or M
4 of a target that is g and a target that is PbO
The method for manufacturing a ferroelectric thin film according to claim 10, wherein a plurality of targets, which are combinations of types, are used. 18. The sputtering target is P
bTiO₃Or [PbO + TiO₂] Is the target
To and La₂O₃Target and MnO ₂Or
Of the target that is Mn and the target that is PbO,
Use multiple targets that are a combination of four types
The method for manufacturing a ferroelectric thin film according to claim 10. 19. The method for producing a ferroelectric thin film according to claim 10, wherein the target of the sputtering method is a material obtained by pressing and molding ceramic or powder in the case of an oxide, and a metal plate in the case of a simple substance. 20. The sputtering condition is that the temperature is 5
50 to 650 ° C. range, pressure is 0.1 to 2.0 Pa, input power is 1.5 per unit target area
The method for producing a ferroelectric thin film according to claim 10, wherein the atmosphere gas is ˜3.5 W / cm ² , and the atmosphere gas is a mixed gas of argon and oxygen.