JP7320091B2 - Laminated substrate with piezoelectric thin film, method for manufacturing laminated substrate with piezoelectric thin film, piezoelectric thin film element, sputtering target material, and method for manufacturing sputtering target material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminated substrate with a piezoelectric thin film, a piezoelectric thin film element, and a manufacturing method thereof.

Piezoelectric materials are widely used in functional electronic components such as sensors and actuators. Lead-based materials, particularly PZT-based ferroelectrics represented by the composition formula Pb(Zr _1-x Ti _x )O ₃ are widely used as piezoelectric materials. A PZT-based piezoelectric body can be produced by a sintering method of sintering a plurality of kinds of oxides.

In recent years, there has been a strong demand for thinner piezoelectric materials and higher performance. However, when the thickness of the piezoelectric body produced by the sintering method approaches the size of the crystal grains forming the piezoelectric body, for example, 10 μm, the deterioration of the characteristics becomes remarkable. Therefore, as a method to replace the sintering method, a new method applying a thin film technology such as a sputtering method is being researched.

Moreover, the PZT-based piezoelectric body contains about 60 to 70 wt % of lead, which is not preferable from the viewpoint of pollution prevention. _Various lead-free piezoelectric materials are _currently being researched _. Also referred to as KNN) (see, for example, Patent Documents 1 and 2). KNN exhibits relatively good piezoelectric properties and is expected to be a strong candidate for lead-free piezoelectric materials.

JP 2007-184513 A JP 2008-159807 A

An object of the present invention is to improve the film properties of a piezoelectric thin film formed using an alkali niobium oxide.

According to one aspect of the invention,
a substrate, an electrode film formed on the substrate, and a piezoelectric thin film formed on the electrode film,
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
A laminated substrate with a piezoelectric thin film containing a metal element selected from the group consisting of Mn and Cu at a concentration of 0.2 at % or more and 0.6 at % or less is provided.

According to another aspect of the invention,
a substrate, an electrode film formed on the substrate, and a piezoelectric thin film formed on the electrode film,
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
an etching rate of 0.005 μm/hr or less when etched using a fluorine-based etchant containing hydrogen fluoride at a concentration of 4.32 mol/L and ammonium fluoride at a concentration of 10.67 mol/L;
A laminated substrate with a piezoelectric thin film having a dielectric constant of 300 or more and 1000 or less when measured at a frequency of 1 kHz is provided.

According to yet another aspect of the invention,
a lower electrode film, a piezoelectric thin film formed on the lower electrode film, and an upper electrode film formed on the piezoelectric thin film;
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
A piezoelectric thin film element containing a metal element selected from the group consisting of Mn and Cu at a concentration of 0.2 at % or more and 0.6 at % or less is provided.

According to yet another aspect of the invention,
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation, and from the group consisting of Mn and Cu preparing a laminated substrate with a piezoelectric thin film containing the selected metal element at a concentration of 0.2 at % or more and 0.6 at % or less;
a step of supplying a fluorine-based etchant to the laminated substrate while exposing at least a portion of the piezoelectric thin film to etch at least a portion of a portion of the laminated substrate excluding the piezoelectric thin film;
A method for manufacturing a piezoelectric thin film element having

According to yet another aspect of the invention,
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation, and from the group consisting of Mn and Cu preparing a laminated substrate with a piezoelectric thin film containing the selected metal element at a concentration of 0.2 at % or more and 0.6 at % or less;
The piezoelectric thin film acts as an etching stopper when a fluorine-based etchant is supplied to the insulating film formed on the piezoelectric thin film to etch a portion of the insulating film to expose the surface of the piezoelectric thin film. a step of controlling the etching end point of the insulating film by causing the
A method for manufacturing a piezoelectric thin film element having

According to the present invention, it is possible to improve the film properties of a piezoelectric thin film formed using alkali niobium oxide.

It is a figure which shows the cross-section of the laminated substrate in one Embodiment of this invention. It is a figure which shows the cross-section of the laminated substrate in other embodiment of this invention. 1 is a schematic diagram showing the crystal structure of potassium sodium niobate; FIG. 1 is a schematic configuration diagram of a piezoelectric thin film device according to an embodiment of the present invention; FIG. It is a figure which shows one process of the manufacturing process of the piezoelectric thin film element in one Embodiment of this invention. It is a figure which shows one process of the manufacturing process of the piezoelectric thin film element in one Embodiment of this invention. It is a figure which shows one process of the manufacturing process of the piezoelectric thin film element in one Embodiment of this invention. (a) shows evaluation results regarding the etching resistance of the piezoelectric thin film, (b) shows evaluation results regarding the insulating property of the piezoelectric thin film, and (c) shows evaluation regarding the dielectric constant of the piezoelectric thin film.

<First embodiment>
An embodiment of the present invention will be described below.

(1) Structure of Laminated Substrate As shown in FIG. and an upper electrode film 4 formed on the piezoelectric thin film 3 .

As the substrate 1, a single crystal silicon (Si) substrate 1a on which a surface oxide film (SiO ₂ film) 1b such as a thermal oxide film or a CVD (Chemical Vapor Deposition) oxide film is formed, that is, a Si substrate with a surface oxide film is used. It can be used preferably. As the substrate 1, a Si substrate 1a having an exposed surface such as a Si (100) plane or a Si (111) plane, that is, a Si substrate having no surface oxide film can be used. Further, as the substrate 1, an SOI (Silicon On Insulator) substrate, a quartz glass ( _SiO2 ) substrate, a gallium arsenide (GaAs) _substrate , a sapphire ( _Al2O3 ) substrate, a metal substrate made of stainless steel or the like can also be used. . The thickness of the single crystal Si substrate 1a can be, for example, 300 to 1000 μm, and the thickness of the surface oxide film 1b can be, for example, 100 to 300 nm.

The lower electrode film 2 can be formed using platinum (Pt), for example. The lower electrode film 2 becomes a single crystal film or a polycrystal film (hereinafter also referred to as a Pt film). Preferably, the crystals forming the Pt film are preferentially oriented in the (111) plane orientation with respect to the surface of the substrate 1 . That is, it is preferable that the surface of the Pt film (the surface serving as the base of the piezoelectric thin film 3) is mainly composed of the Pt (111) plane. The Pt film can be formed using methods such as sputtering and vapor deposition. The lower electrode film 2 is made of various metals other than Pt, such as gold (Au), ruthenium (Ru), and iridium ( _Ir ); ₃ ) can also be used to form a film using a metal oxide or the like. In order to increase the adhesion between the substrate 1 and the lower electrode film 2, for example, titanium (Ti), tantalum (Ta), titanium oxide (TiO ₂ ), nickel (Ni), etc., are placed as main components. An adhesion layer 6 is provided. The adhesion layer 6 can be formed by using a technique such as a sputtering method or a vapor deposition method. The thickness of the lower electrode film 2 can be, for example, 100 to 300 nm, and the thickness of the adhesion layer 6 can be, for example, 1 to 20 nm.

The piezoelectric thin film 3 contains, for example, potassium (K), sodium (Na), and niobium (Nb), and is an alkaline niobium oxide represented by the composition formula (K _1-x Na _x )NbO ₃ , that is, potassium niobate. A film can be formed using sodium (KNN). The coefficient x[=Na/(K+Na)] in the above composition formula should be within the range of 0<x<1, preferably 0.4≦x≦0.7. The piezoelectric thin film 3 is a KNN polycrystalline film (hereinafter also referred to as a KNN thin film). The crystal structure of KNN is a perovskite structure as shown in FIG. It is preferable that the crystals forming the KNN thin film are preferentially oriented in the (001) plane orientation with respect to the surface of the substrate 1 . That is, it is preferable that the surface of the KNN thin film (the surface serving as the base of the upper electrode film 4) is mainly composed of the KNN (001) plane. By directly forming a KNN thin film on a Pt film preferentially oriented in the (111) plane orientation with respect to the surface of the substrate 1, the crystals constituting the KNN thin film are oriented in the (001) plane with respect to the surface of the substrate 1. It is possible to preferentially align the azimuth. For example, 80% or more of the crystal group constituting the KNN thin film is oriented in the (001) plane orientation with respect to the surface of the substrate 1, and 80% or more of the surface of the KNN thin film is the KNN (001) plane. It becomes possible to The KNN thin film can be formed using methods such as a sputtering method, a PLD (Pulsed Laser Deposition) method, and a sol-gel method. The thickness of the piezoelectric thin film 3 can be, for example, 1 to 5 μm.

The piezoelectric thin film 3 preferably contains, for example, a metal element selected from the group consisting of manganese (Mn) and copper (Cu) at a concentration within the range of 0.2 at % or more and 0.6 at % or less. This point will be described later.

The upper electrode film 4 can be formed using, for example, various metals such as Pt, Au, aluminum (Al), Cu, and alloys thereof. The upper electrode film 4 can be formed using methods such as a sputtering method, a vapor deposition method, a plating method, and a metal paste method. The upper electrode film 4 does not greatly affect the crystal structure of the piezoelectric thin film 3 like the lower electrode film 2 does. Therefore, the material, crystal structure, and film forming method of the upper electrode film 4 are not particularly limited. Between the piezoelectric thin film 3 and the upper electrode film 4, an adhesion layer containing, for example, Ti, Ta, TiO ₂ , Ni, or the like as a main component may be provided in order to improve adhesion therebetween. The thickness of the upper electrode film 4 can be, for example, 100 to 1000 nm, and the thickness of the adhesion layer can be, for example, 1 to 20 nm.

(2) Configuration of Piezoelectric Thin Film Device FIG. 4 shows a schematic configuration diagram of the piezoelectric thin film device 30 according to the present embodiment. The piezoelectric thin film device 30 includes at least a piezoelectric thin film element 20 obtained by molding the laminated substrate 10 into a predetermined shape, and a voltage detecting means 11a or a voltage applying means 11b connected to the piezoelectric thin film element 20. Configured.

By connecting the voltage detection means 11a between the lower electrode film 2 and the upper electrode film 4 of the piezoelectric thin film element 20, the piezoelectric thin film device 30 can function as a sensor. When the piezoelectric thin film 3 is deformed due to some change in physical quantity, a voltage is generated between the lower electrode film 2 and the upper electrode film 4 due to the deformation. By detecting this voltage with the voltage detection means 11a, the magnitude of the physical quantity applied to the piezoelectric thin film 3 can be measured. In this case, applications of the piezoelectric thin film device 30 include, for example, an angular velocity sensor, an ultrasonic sensor, a pressure sensor, an acceleration sensor, and the like.

By connecting the voltage applying means 11b between the lower electrode film 2 and the upper electrode film 4 of the piezoelectric thin film element 20, the piezoelectric thin film device 30 can function as an actuator. By applying a voltage between the lower electrode film 2 and the upper electrode film 4 by the voltage applying means 11b, the piezoelectric thin film 3 can be deformed. Various members connected to the piezoelectric thin film device 30 can be operated by this deformation operation. In this case, applications of the piezoelectric thin film device 30 include, for example, heads for inkjet printers, MEMS mirrors for scanners, vibrators for ultrasonic generators, and the like.

(3) Addition of Mn and Cu to the Piezoelectric Thin Film As described above, the piezoelectric thin film 3 of the present embodiment contains 0.2 at % or more and 0.6 at % or less of the metal element selected from the group consisting of Mn and Cu. Contained at a concentration within the range of The effect obtained by this will be described below.

(a) By adding Mn or Cu to the piezoelectric thin film 3 at a concentration within the above range, it is possible to improve the insulation (leakage resistance) of the piezoelectric thin film 3 . For example, by setting the Cu concentration in the piezoelectric thin film 3 to 0.2 at % or more and 0.6 at % or less, when an electric field of 25×10 ⁶ V/m is applied to the piezoelectric thin film 3 in its thickness direction, It is possible to reduce the leakage current density to 500 μA/cm ² or less, preferably 300 μA/cm ² or less. Further, for example, by setting the Mn concentration in the piezoelectric thin film 3 to 0.2 at % or more and 0.6 at % or less, it is possible to obtain the same insulating properties as in the case where the Cu concentration in the piezoelectric thin film 3 is within the above range. It becomes possible. By improving the insulating properties of the piezoelectric thin film 3, it is possible to improve the performance of the piezoelectric thin film device 30, such as a sensor or an actuator, which is produced by processing the laminated substrate 10 described above.

(b) By adding Cu to the piezoelectric thin film 3 at a concentration within the above range, it is possible to improve resistance to the fluorine-based etchant, that is, etching resistance, in addition to the above-described insulating properties. For example, by setting the Cu concentration in the piezoelectric thin film 3 to 0.2 at % or more and 0.6 at % or less, hydrogen fluoride (HF) is 4.32 mol/L and ammonium fluoride (NH ₄ F) is 10.67 mol/L. The etching rate of the piezoelectric thin film 3 when the piezoelectric thin film 3 is immersed in a buffered hydrofluoric acid (BHF) solution containing a concentration of /L can be 0.005 μm/hr or less. The inventors of the present invention have already confirmed that when the BHF solution was supplied to the piezoelectric thin film 3 under the above conditions, etching of the piezoelectric thin film 3 did not progress even after 60 minutes.

By improving the etching resistance of the piezoelectric thin film 3, the following merits can be obtained, for example.

For example, as shown in FIG. 5A, a substrate 1 having surface oxide films 1b and 1c formed on the front and rear surfaces of a single crystal Si substrate 1a is prepared, and an adhesion layer is formed on the surface oxide film 1b on the front surface side. 6. Let us consider the processing after manufacturing the laminated substrate 10 by forming the lower electrode film 2 and the piezoelectric thin film 3 in this order. In this case, as shown in FIG. 5B, a BHF solution or the like may be used to etch the front surface electrode film 1c on the rear surface side. When performing this treatment, by increasing the etching resistance of the piezoelectric thin film 3 as described above, it becomes unnecessary to form a protective film for protecting the exposed surface 3a of the piezoelectric thin film 3, thereby simplifying the processing process. It becomes possible.

Further, for example, as shown in FIG. 6A, a surface oxide film 1b is formed on the surface of an SOI substrate in which a single crystal Si substrate 1a, a BOX layer (SiO ₂ layer) 1e and a Si layer 1f are laminated in this order. A laminated substrate 10 is manufactured by forming an adhesion layer 6, a lower electrode layer 2 and a piezoelectric thin film 3 in this order on the surface oxide film 1b. Consider the processing after the part is removed by Deep-RIE or wet etching. In this case, as shown in FIG. 6B, a process of removing a portion of the BOX layer 1e left on the back side of the Si layer 1f using a BHF solution or the like may be performed. Even when performing this process, by increasing the etching resistance of the piezoelectric thin film 3 as described above, it becomes unnecessary to form a protective film for protecting the exposed surface 3a of the piezoelectric thin film 3, thereby simplifying the processing process. becomes possible.

For example, as shown in FIG. 7A, let us consider a process after forming an insulating film (SiO ₂ film) 7 and an etching mask 7m in this order on the piezoelectric thin film 3 after patterning. In this case, as shown in FIG. 7B, in order to expose the film forming region of the upper electrode film 4, a process of etching a part of the insulating film 7 using a BHF solution or the like may be performed. When performing this process, by increasing the etching resistance of the piezoelectric thin film 3 underlying the insulating film 7 as described above, the piezoelectric thin film 3 can function as an etching stopper, and the end point of the etching process can be accurately controlled. becomes possible. In addition, as an etchant, a BHF solution or the like having a stronger etching power than an etching gas such as hydrogen fluoride (HF) gas can be used, and the efficiency of the etching process can be improved. Moreover, even when wet etching is performed using a BHF solution or the like, etching damage to the piezoelectric thin film 3 due to the etching process can be suppressed.

Although the effect of improving the etching resistance described above can be obtained particularly remarkably when Cu is added to the piezoelectric thin film 3, it has characteristics that are difficult to obtain when Mn is added to the piezoelectric thin film 3. By utilizing this characteristic, it is possible to appropriately finely adjust the etching resistance of the piezoelectric thin film 3 while improving the insulation of the piezoelectric thin film 3 . For example, both Mn and Cu are added to the piezoelectric thin film 3 at concentrations within the above range, and the ratio of the Cu concentration to the total concentration of Mn and Cu (Cu/Mn+Cu) is brought close to 1. It is possible to control so as to increase the etching resistance while increasing the insulation as described above. Further, for example, by bringing the ratio (Cu/Mn+Cu) closer to 0, it is possible to control the increase in etching resistance appropriately while enhancing the insulation of the piezoelectric thin film 3 as described above. .

(c) By adding Mn or Cu to the piezoelectric thin film 3 at a concentration within the range described above, it is possible to make the dielectric constant of the piezoelectric thin film 3 suitable for applications such as sensors and actuators. . For example, by setting the Cu concentration in the piezoelectric thin film 3 to 0.2 at % or more and 0.6 at % or less, the dielectric constant of the piezoelectric thin film 3 measured under conditions of a frequency of 1 kHz and ±1 V can be set to 1000 or less. It becomes possible. Further, for example, by setting the Mn concentration in the piezoelectric thin film 3 to 0.2 at % or more and 0.6 at % or less, the dielectric constant of the piezoelectric thin film 3 can be made 1000 or less.

(d) By adding Mn or Cu to the piezoelectric thin film 3 in the concentration range described above, the film characteristics of the piezoelectric thin film 3 can be improved. In other words, it is possible to enhance the insulating properties of the piezoelectric thin film 3 and make the dielectric constant of the piezoelectric thin film 3 appropriate. Further, by adding Cu to the piezoelectric thin film 3 within the concentration range described above, it is possible to increase the etching resistance of the piezoelectric thin film 3 in addition to the above effects. Further, by adding both Mn and Cu to the piezoelectric thin film 3 within the concentration range described above, it is possible to appropriately finely adjust the etching resistance of the piezoelectric thin film 3 while obtaining the above effects.

In order to obtain the above effects in a well-balanced manner, the concentrations of Mn and Cu in the piezoelectric thin film 3 must be 0.2 at % or more and 0.6 at % or less. As will be described later, if the total concentration of Mn and Cu in the piezoelectric thin film 3 is less than 0.2 at %, the insulating effect described above may not be obtained. Also, if the Cu concentration in the piezoelectric thin film 3 is less than 0.2 at %, the effect of etching resistance described above may not be obtained. Further, when the total concentration of Mn and Cu in the piezoelectric thin film 3 exceeds 0.6 at %, the dielectric constant of the piezoelectric thin film 3 becomes excessively large, resulting in a decrease in sensitivity when applied to a sensor or an actuator. may lead to an increase in power consumption. One of the reasons for this is thought to be that as the amount of Mn or Cu added increases, it becomes difficult to preferentially orient the crystals forming the piezoelectric thin film 3 in the (001) orientation with respect to the surface of the substrate 1. be done.

(4) Modifications The present embodiment is not limited to the above aspects, and can be modified as follows, for example.

For example, the concentration of Mu or Cu in the piezoelectric thin film 3 may be 0.2 atomic % or more and 0.25% or less. In this case, it is possible to reduce the dielectric constant of the piezoelectric thin film 3 within the range described above while obtaining the above-described effects of insulation and etching resistance. For example, the dielectric constant of the piezoelectric thin film 3 measured under conditions of a frequency of 1 kHz and ±1 V can be set within a range of 300-400. The laminated substrate 10 configured in this manner can be particularly suitably used for applications such as high-sensitivity sensors that require a low dielectric constant.

Further, for example, the concentration of Mu or Cu in the piezoelectric thin film 3 may be 0.5 at % or more and 0.6 at % or less. In this case, the insulating properties of the piezoelectric thin film 3 can be further enhanced while obtaining the above-described effects of insulating properties and etching resistance. For example, it is possible to reduce the leakage current density to 500 μA/cm ² or less when an electric field of 25×10 ⁶ V/m is applied to the piezoelectric thin film 3 in its thickness direction. The laminated substrate 10 configured in this manner can be particularly suitably used for applications such as actuators that require a high breakdown voltage.

Further, for example, the concentration of Cu in the piezoelectric thin film 3 may be 0.4 at % or more and 0.6 at % or less. In this case, the etching resistance of the piezoelectric thin film 3 can be further enhanced while obtaining the above-described effects of insulation and dielectric constant. For example, the etching rate of the piezoelectric thin film 3 when the piezoelectric thin film 3 is immersed in the BHF solution having the concentration described above can be set to 0.005 μm/hr or less.

<Second embodiment>
While adding Mn or Cu into the piezoelectric thin film 3 as in the first embodiment, the out-of-plane lattice constant c and the in-plane lattice of the crystal that constitutes the piezoelectric thin film 3, that is, the alkali niobium oxide The ratio c/a to the constant a may be controlled as follows.

For example, the lattice constant ratio is adjusted so that the ratio between the out-of-plane lattice constant c and the in-plane lattice constant a of the crystals forming the piezoelectric thin film 3 is within the range of 0.98≦c/a≦1.01. may be controlled. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧90 pm/V, making it possible to improve the piezoelectric characteristics.

When the piezoelectric thin film 3 has a plurality of layers represented by the composition formula (K _1−x Na _x )NbO ₃ (0<x<1), at least the thickest layer among these layers is The lattice constant ratio may be controlled so that the ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal to be formed is within the range of 0.98≦c/a≦1.01. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧90 pm/V, making it possible to improve the piezoelectric characteristics.

Further, for example, when a tensile stress is generated in the piezoelectric thin film 3, the ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal constituting the piezoelectric thin film 3 is set to 0.980≦c/a≦0.993. The lattice constant ratio may be controlled so as to be within the range. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧90 pm/V, making it possible to improve the piezoelectric characteristics. In this case, the piezoelectric thin film 3 is preferably provided on the stress relaxation layer made of a crystal having a lattice constant smaller than that of the crystal forming the piezoelectric thin film 3 .

Further, for example, when compressive stress is generated in the piezoelectric thin film 3, the ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal constituting the piezoelectric thin film 3 is set to 1.004≦c/a≦1.010. The lattice constant ratio may be controlled so as to be within the range. In this case, the piezoelectric thin film 3 is preferably provided on the stress relaxation layer made of a crystal having a lattice constant larger than that of the crystal forming the piezoelectric thin film 3 .

The above c/a ratio can be adjusted by controlling the partial pressure of H ₂ O present in the mixed atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas during sputtering deposition. An Ar/O ₂ mixed gas is used as the atmosphere gas for sputtering film formation, but moisture existing inside the chamber may be mixed in the atmosphere gas, although the proportion is very small. The c/a ratio of the KNN thin film greatly depends on the orientation of the (001) plane orientation of the KNN thin film. /a ratio tends to be small. _The (001) orientation state of this KNN thin film greatly depends on the H ₂ O partial pressure _contained in the atmospheric gas during sputtering film formation. When the partial pressure is low, the (001) orientation tends to be high. That is, by strictly controlling the H ₂ O partial pressure in the atmospheric gas, the c/a ratio of the KNN thin film can be controlled.

<Third Embodiment>
While adding Mn and Cu into the piezoelectric thin film 3 as in the first embodiment, the composition ratio of the substance constituting the piezoelectric thin film 3, that is, the alkali niobium oxide is controlled as follows. good too.

For example, the piezoelectric thin film 3 has a perovskite structure represented by the composition formula (K _1−x Na _x ) _y NbO ₃ and having a range of 0.4≦x≦0.7 and 0.7≦y≦0.94. Alkaline niobium oxide may be used for film formation. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧90 pm/V, making it possible to improve the piezoelectric characteristics. It is also possible to more reliably improve the insulation resistance of the piezoelectric thin film. For example, it is possible to set the leakage current density to 0.1 μA/cm ² or less when an electric field of 50 kV/cm is applied in the thickness direction of the piezoelectric thin film 3 .

Further, for example, the piezoelectric thin film 3 has a perovskite structure represented by the composition formula (K _1−x Na _x ) _y NbO ₃ and having a range of 0.4≦x≦0.7 and 0.75≦y≦0.90. Alkaline niobium oxide may be used to form the film. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧100 pm/V, making it possible to improve the piezoelectric characteristics. It is also possible to more reliably improve the insulation resistance of the piezoelectric thin film. For example, it is possible to set the leakage current density to 0.1 μA/cm ² or less when an electric field of 50 kV/cm is applied in the thickness direction of the piezoelectric thin film.

The above composition ratio can be adjusted, for example, by controlling the composition of the target material used during sputtering film formation. The target material can be produced, for example, by mixing K ₂ CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O ₅ powder, etc. and firing the mixture. In this case, the composition of the target material can be controlled by adjusting the mixing ratio of K ₂ CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O ₅ powder, and the like.

<Fourth Embodiment>
While adding Mn or Cu to the piezoelectric thin film 3 as in the first embodiment, the composition ratio of the substances constituting the piezoelectric thin film 3, the out-of-plane lattice constant c, and the in-plane lattice constant a You may control ratio c/a as follows, respectively.

For example, the piezoelectric thin film 3 has a perovskite structure represented by the composition formula (K _1−x Na _x ) _y NbO ₃ and having a range of 0.4≦x≦0.7 and 0.77≦y≦0.90. The film is formed using alkali niobium oxide, and the ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystals forming the piezoelectric thin film 3 is 0.98≦c/a≦1.008. The lattice constant ratio may be controlled so as to be within the range. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧90 pm/V, making it possible to improve the piezoelectric characteristics. It is also possible to more reliably improve the insulation resistance of the piezoelectric thin film. For example, it is possible to set the leakage current density to 0.1 μA/cm ² or less when an electric field of 50 kV/cm is applied in the thickness direction of the piezoelectric thin film 3 .

When the piezoelectric thin film 3 has a plurality of layers represented by the composition formula (K _1−x Na _x )NbO ₃ (0<x<1), at least the thickest layer among these layers is The lattice constant ratio may be controlled so that the ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal to be formed is in the range of 0.98≦c/a≦1.008. Also in this case, the same effect as in the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies |d ₃₁ |≧90 pm/V, making it possible to improve the piezoelectric characteristics.

The above c/a ratio and composition ratio can be controlled by the methods described in the second and third embodiments.

<Fifth Embodiment>
While adding Mn and Cu into the piezoelectric thin film 3 as in the first embodiment, the concentrations of carbon (C) and hydrogen (H) in the piezoelectric thin film 3 are controlled as follows. good too.

For example, the C concentration in the piezoelectric thin film 3 may be 2×10 ¹⁹ cm ⁻³ or less, or the H concentration may be 4×10 ¹⁹ cm ⁻³ or less when measured using SIMS. Also in these cases, the same effects as in the first embodiment can be obtained. It is also possible to more reliably improve the dielectric strength of the piezoelectric thin film 3 . For example, it is possible to set the leakage current density to 0.1 μA/cm ² or less when an electric field of 50 kV/cm is applied in the thickness direction of the piezoelectric thin film 3 . It is also possible to set the dielectric loss tan δ of the piezoelectric thin film 3 to 0.1 or less.

Further, for example, the C concentration in the piezoelectric thin film 3 may be 2×10 ¹⁹ cm ⁻³ or less and the H concentration may be 4×10 ¹⁹ cm ⁻³ or less. Also in this case, the same effect as in the first embodiment can be obtained. It is also possible to more reliably improve the dielectric strength of the piezoelectric thin film 3 . For example, when an electric field of 50 kV/cm is applied in the thickness direction of the piezoelectric thin film 3, the leakage current density can be reduced to 0.1 μA/cm ² or less. It is also possible to set the dielectric loss tan δ of the piezoelectric thin film 3 to 0.1 or less.

In order to reduce the C concentration and H concentration in the piezoelectric thin film 3, it is effective to reduce the C concentration and H concentration in the KNN sintered body target used in sputtering. It is possible to reduce the C concentration and the H concentration in the sintered target by increasing the firing temperature when producing the sintered target. It is also effective to increase the ratio of O ₂ in the atmosphere gas, for example, the mixed gas of Ar gas and O ₂ gas, when performing the sputtering film forming process. It is also effective to perform heat treatment in the air or in an oxygen atmosphere after forming the piezoelectric thin film 3 .

<Sixth embodiment>
As shown in FIG. 2, as the substrate 1, a Si substrate 1a having an insulating film 1d made of an insulating material other than SiO ₂ formed on its surface can also be used. Even when the adhesion layer 6, the lower electrode film 2, the piezoelectric thin film 3, and the upper electrode film 4 are formed in this order on the insulating film 1d, the composition and crystal orientation of the piezoelectric thin film 3 are the same as those of the above embodiments. By controlling as follows, effects similar to those of these embodiments and the like can be obtained. As in the first embodiment, an adhesion layer may be provided between the piezoelectric thin film 3 and the upper electrode film 4 .

<Other embodiments>
The embodiments of the present invention have been specifically described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, the first to sixth embodiments described above can be combined as appropriate.

Experimental results that support the effects of the above-described embodiments will be described below.

As a substrate, a Si substrate having a (100) surface orientation, a thickness of 610 μm, a diameter of 6 inches, and a thermal oxide film (thickness of 200 nm) formed on the surface was prepared. Then, on the thermally oxidized film of this substrate, a Ti layer (thickness 2 nm) as an adhesion layer and a Pt film (preferentially oriented in the (111) plane orientation with respect to the surface of the substrate, thickness 200 nm) as a lower electrode film were formed. , and a KNN thin film (preferentially oriented in the (100) plane orientation with respect to the surface of the substrate, thickness 2 μm) as a piezoelectric thin film were sequentially formed to fabricate a laminated substrate. The Cu concentration (CuO concentration) in the KNN thin film was varied within the range of 0 to 1 at %.

The Ti layer, Pt film, and KNN thin film were all formed by RF magnetron sputtering. The processing conditions for depositing the Ti layer and the Pt film were respectively a substrate temperature of 300.degree. The processing conditions for forming _{the KNN thin} film are as follows: substrate temperature 600° C.; The speed was 1 μm/hr.

As a sputtering target material for forming a KNN thin film to which Cu is added, it has a composition of (K + Na) / Nb = 0.8 to 1.2 and Na / (K + Na) = 0.4 to 0.7. A (K _1−x Na _x ) _y NbO ₃ sintered body containing Cu at a concentration of 0.2 at % or more and 0.6 at % or less was used. The target material was prepared by mixing K ₂ CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O ₅ powder, and CuO powder using a ball mill for 24 hours, prefiring at 850° C. for 10 hours, and then using a ball mill again. It was prepared by pulverizing, molding at a pressure of 200 MPa, and firing at 1080°C. The composition of the target material is controlled by adjusting the mixing ratio of K ₂ CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O ₅ powder, and CuO powder. line spectroscopy). In the evaluation described later, the sputtering target material for forming a KNN thin film to which Mn is added is the above-mentioned (K _{A 1-x} Na _x ) _y NbO ₃ sintered body was used. When producing the sintered body, MnO powder was used instead of CuO powder in the above-described production procedure.

Then, the etching resistance, insulating properties, and dielectric constant of the KNN thin film of the laminated substrate were measured. FIG. 8(a) shows the evaluation result of the etching resistance of the KNN thin film, FIG. 8(b) shows the evaluation result of the insulation property of the KNN thin film, and FIG. 8(c) shows the evaluation of the dielectric constant of the KNN thin film. be.

(Evaluation on etching resistance)
Etching resistance was evaluated by immersing the laminated substrate in a BHF solution with the surface of the KNN thin film exposed, and measuring the time until the surface of the KNN thin film started to be corroded. The HF concentration in the BHF solution was 4.32 mol/L, and the NH ₄ F concentration was 10.67 mol/L.

As shown in FIG. 8A, it was confirmed that the surface of the KNN thin film with a Cu concentration of 0 at % started to erode in less than 1 minute after being immersed in the BHF solution. In the KNN thin film with a Cu concentration of 0.1 at %, etching of the KNN thin film is relatively difficult to proceed, but it was confirmed that corrosion started about 1 minute after immersion. It was confirmed that the KNN thin film with a Cu concentration of 0.2 at % could avoid surface erosion for at least 15 minutes after immersion. It was confirmed that the KNN thin film with a Cu concentration of 0.5 at % could avoid surface erosion for at least 60 minutes after immersion.

That is, by setting the Cu concentration in the KNN thin film to 0.2 at% or more, the etching resistance of the KNN thin film can be dramatically improved. It was confirmed that the etching resistance of the thin film could be further enhanced. It has already been confirmed that the above effect on etching resistance is difficult to obtain when Mn is added instead of Cu to the KNN thin film.

(Evaluation regarding insulation)
In the evaluation of insulation, a circular Pt film with a diameter of 0.5 mm was formed as an upper electrode film on the KNN thin film, and a voltage was applied between the lower electrode film and the upper electrode film. It was carried out by measuring the voltage value until a leak current of 500 μA/cm ² flows.

As shown in FIG. 8(b), in the KNN thin film with a Cu concentration of 0 at%, it was confirmed that a leakage current of 500 μA/cm ² flows when a voltage of 2 to 4 V is applied in the film thickness direction. did it. It was also confirmed that in a KNN thin film with a Cu concentration of 0.1 at %, a leak current of 500 μA/cm ² flows when a voltage of 5 to 7 V is applied in the film thickness direction.

On the other hand, in the KNN thin film with a Cu concentration of 0.2 at%, it was confirmed that a voltage of 30 to 34 V must be applied in the film thickness direction in order to allow a leak current of 500 μA/cm ² to flow. did it. In addition, in the KNN thin film with a Cu concentration of 0.25 at% in the film, even if a voltage of 50 V was applied in the film thickness direction, a leakage current of 500 μA/cm ² or more was not observed, and the magnitude of the leakage current was the maximum. However, it was confirmed to be 300 μA/cm ² or less. It was also confirmed that in the KNN thin film with a Cu concentration of 0.5 at % or more, no leak current of 500 μA/cm ² or more was observed even when a voltage of 100 V was applied in the film thickness direction.

That is, by setting the Cu concentration in the KNN thin film to 0.2 at% or more, the insulating properties of the KNN thin film can be dramatically improved, and the Cu concentration in the film can be 0.25 at%, or even 0.5 at%. % or more, it was confirmed that the insulating properties of the KNN thin film can be further improved. It has already been confirmed that the above-mentioned insulating effect can be obtained even when Mn is added to the KNN thin film instead of Cu, in the same manner as when Cu is added to the KNN thin film. A preferable Mn concentration range in this case is the same as the Cu concentration range described above.

(Evaluation on dielectric constant)
The dielectric constant was evaluated by applying an AC electric field of 1 kHz and ±1 V to the KNN thin film.

As shown in FIG. 8(c), it was confirmed that the dielectric constant exceeded 1000 in the KNN thin film with a Cu concentration of 0.7 at % or higher. It was also confirmed that a KNN thin film with a Cu concentration of 0.6 at % or higher has a dielectric constant of less than 1000. It was also confirmed that the KNN thin film with a Cu concentration of 0.25 at % or less had a dielectric constant of less than 400.

That is, by setting the Cu concentration in the KNN thin film to 0.6 at% or less, the dielectric constant of the KNN thin film can be made suitable for use in sensors and actuators. It was confirmed that by setting the content to 0.25 at % or less, the dielectric constant of the KNN thin film can be made suitable for use in highly sensitive sensors. It has already been confirmed that the above-mentioned effect on the dielectric constant can be obtained even when Mn is added to the KNN thin film instead of Cu, in the same way as when Cu is added to the KNN thin film. A preferable Mn concentration range in this case is the same as the Cu concentration range described above.

<Preferred embodiment of the present invention>
Preferred embodiments of the present invention are described below.

(Appendix 1)
According to one aspect of the invention,
a substrate, an electrode film formed on the substrate, and a piezoelectric thin film formed on the electrode film,
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
A laminated substrate with a piezoelectric thin film containing a metal element selected from the group consisting of Mn and Cu at a concentration of 0.2 at % or more and 0.6 at % or less is provided.

(Appendix 2)
Preferably, the laminated substrate with a piezoelectric thin film according to Appendix 1,
A concentration of the metal element in the piezoelectric thin film is 0.2 atomic % or more and 0.25% or less.

(Appendix 3)
Also preferably, the laminated substrate with a piezoelectric thin film according to Appendix 1,
A concentration of the metal element in the piezoelectric thin film is 0.5 at % or more and 0.6 at % or less.

(Appendix 4)
Also preferably, the laminated substrate with a piezoelectric thin film according to Appendix 1,
A concentration of the metal element in the piezoelectric thin film is 0.4 at % or more and 0.6 at % or less.

(Appendix 5)
According to another aspect of the invention,
a substrate, an electrode film formed on the substrate, and a piezoelectric thin film formed on the electrode film,
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
an etching rate of 0.005 μm/hr or less when etched using a fluorine-based etchant containing hydrogen fluoride at a concentration of 4.32 mol/L and ammonium fluoride at a concentration of 10.67 mol/L;
a leakage current density of 500 μA/cm ² or less (preferably 300 μA/cm ² or less) when an electric field of 25×10 ⁶ V/m is applied in the thickness direction;
A laminated substrate with a piezoelectric thin film having a dielectric constant of 300 or more and 1000 or less when measured at a frequency of 1 kHz is provided.

(Appendix 6)
Also preferably, the laminated substrate with a piezoelectric thin film according to any one of Appendices 1 to 5,
The ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal (alkali niobium oxide) forming the piezoelectric thin film is within the range of 0.98≦c/a≦1.01,
The absolute value of the piezoelectric constant of the piezoelectric thin film satisfies |d ₃₁ |≧90 pm/V.

(Appendix 7)
Also preferably, the laminated substrate with a piezoelectric thin film according to appendix 6,
the piezoelectric thin film has a plurality of layers represented by a composition formula of (K _1-x Na _x )NbO ₃ (0<x<1),
The ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal (alkali niobium oxide) constituting at least the thickest layer among the plurality of layers is 0.98≦c/a≦1. 01 range.

(Appendix 8)
Also preferably, the laminated substrate with a piezoelectric thin film according to appendix 6 or 7,
A tensile stress is generated in the piezoelectric thin film, and the ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal (alkali niobium oxide) constituting the piezoelectric thin film is 0.980≦c/a≦0.980≦c/a≦0. 993 range.

(Appendix 9)
Also preferably, the laminated substrate with a piezoelectric thin film according to Appendix 8,
The piezoelectric thin film is provided on the stress relieving layer made of a crystal having a lattice constant smaller than that of the crystal forming the piezoelectric thin film.

(Appendix 10)
Also preferably, the laminated substrate with a piezoelectric thin film according to appendix 6 or 7,
Compressive stress is generated in the piezoelectric thin film, and the ratio between the out-of-plane lattice constant c and the in-plane lattice constant a of the crystal (alkali niobium oxide) forming the piezoelectric thin film is 1.004≦c/a≦1.004≦c/a≦1. 010 range.

(Appendix 11)
Also preferably, the laminated substrate with a piezoelectric thin film according to Appendix 10,
The piezoelectric thin film is provided on the stress relieving layer made of a crystal having a lattice constant larger than that of the crystal forming the piezoelectric thin film.

(Appendix 12)
Also preferably, the laminated substrate with a piezoelectric thin film according to any one of Appendices 1 to 5,
The piezoelectric thin film is
An alkali niobium oxide having a perovskite structure represented by the compositional formula (K _1-x Na _x ) _y NbO ₃ and having a range of 0.4≦x≦0.7 and 0.7≦y≦0.94,
The absolute value of the piezoelectric constant |d ₃₁ | is 90 pm/V or more.

(Appendix 13)
Also preferably, the laminated substrate with a piezoelectric thin film according to any one of Appendices 1 to 5,
The piezoelectric thin film is
An alkali niobium oxide having a perovskite structure represented by the compositional formula (K _1-x Na _x ) _y NbO ₃ and having a range of 0.4≦x≦0.7 and 0.75≦y≦0.90,
The absolute value of the piezoelectric constant |d ₃₁ | is 100 pm/V or more.

(Appendix 14)
Preferably, the laminated substrate with a piezoelectric thin film according to any one of Appendices 1 to 5,
The piezoelectric thin film is
An alkali niobium oxide having a perovskite structure represented by the compositional formula (K _1-x Na _x ) _y NbO ₃ and having a range of 0.4≦x≦0.7 and 0.77≦y≦0.90,
The ratio between the out-of-plane lattice constant c and the in-plane lattice constant a of the crystal (alkali niobium oxide) forming the piezoelectric thin film is in the range of 0.98≦c/a≦1.008.

(Appendix 15)
Preferably, the laminated substrate with a piezoelectric thin film according to appendix 14,
the piezoelectric thin film has a plurality of layers represented by a composition formula of (K _1-x Na _x )NbO ₃ (0<x<1),
The ratio of the out-of-plane lattice constant c to the in-plane lattice constant a of the crystal (alkali niobium oxide) constituting at least the thickest layer among the plurality of layers is 0.98≦c/a≦1. 008 range.

(Appendix 16)
Preferably, the laminated substrate with a piezoelectric thin film according to any one of Appendices 1 to 5,
The piezoelectric thin film has a C concentration of 2×10 ¹⁹ cm ⁻³ or less, or an H concentration of 4×10 ¹⁹ cm ⁻³ or less. More preferably, the piezoelectric thin film has a C concentration of 2×10 ¹⁹ cm ⁻³ or less and an H concentration of 4×10 ¹⁹ cm ⁻³ or less.

(Appendix 17)
According to yet another aspect of the invention,
a lower electrode film, a piezoelectric thin film formed on the lower electrode film, and an upper electrode film formed on the piezoelectric thin film;
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
A piezoelectric thin film element containing a metal element selected from the group consisting of Mn and Cu at a concentration of 0.2 at % or more and 0.6 at % or less is provided.

(Appendix 18)
According to yet another aspect of the invention,
a substrate, a lower electrode film formed on the substrate, a piezoelectric thin film formed on the lower electrode film, and an upper electrode film formed on the piezoelectric thin film;
The piezoelectric thin film is
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation,
A piezoelectric thin film element containing a metal element selected from the group consisting of Mn and Cu at a concentration of 0.2 at % or more and 0.6 at % or less is provided.

(Appendix 19)
According to yet another aspect of the invention,
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation, and from the group consisting of Mn and Cu preparing a laminated substrate with a piezoelectric thin film containing the selected metal element at a concentration of 0.2 at % or more and 0.6 at % or less;
A fluorine-based etchant is supplied to the laminated substrate (without providing a protective film covering the exposed surface of the piezoelectric thin film) in a state in which at least a portion of the piezoelectric thin film is exposed, and the etching at least a portion of the portion excluding the piezoelectric thin film;
A method for manufacturing a piezoelectric thin film element having

(Appendix 20)
According to yet another aspect of the invention,
Alkaline niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is preferentially oriented in the (001) plane orientation, and from the group consisting of Mn and Cu preparing a laminated substrate with a piezoelectric thin film containing the selected metal element at a concentration of 0.2 at % or more and 0.6 at % or less;
The piezoelectric thin film acts as an etching stopper when a fluorine-based etchant is supplied to the insulating film formed on the piezoelectric thin film to etch a portion of the insulating film to expose the surface of the piezoelectric thin film. a step of controlling the etching end point of the insulating film by causing the
A method for manufacturing a piezoelectric thin film element having

(Appendix 21)
According to yet another aspect of the invention,
Composed of a sintered body represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1), containing 0.2 at% or more and 0.6 at% of a metal element selected from the group consisting of Mn and Cu % or less is provided.

(Appendix 22)
Preferably, the sputtering target material according to Appendix 21,
The concentration of the metal element in the sintered body is 0.2 atomic % or more and 0.25% or less.

(Appendix 23)
Also preferably, the sputtering target material according to Appendix 21,
A concentration of the metal element in the sintered body is 0.5 at % or more and 0.6 at % or less.

(Appendix 24)
Also preferably, the sputtering target material according to Appendix 21,
The concentration of the metal element in the sintered body is 0.4 at % or more and 0.6 at % or less.

REFERENCE SIGNS LIST 1 substrate 2 lower electrode film 3 piezoelectric thin film 10 laminated substrate

Claims (9)

a substrate, an electrode film formed on the substrate, and a piezoelectric thin film formed on the electrode film,
The piezoelectric thin film is made of an alkali niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) and is preferentially oriented in the (001) plane orientation, containing Cu and Mn,
The total concentration of Cu and Mn is 0.2 at% or more and 0.6 at% or less,
The ratio of the concentration of Cu to the total concentration of Cu and Mn is more than 0 and less than 1,
Laminated substrate with piezoelectric thin film. 2. The laminated substrate with a piezoelectric thin film according to claim 1, wherein the ratio of the concentration of Cu to the total concentration of Cu and Mn is 0.67 or more and less than 1. 3. The laminated substrate with a piezoelectric thin film according to claim 1, wherein the ratio of the concentration of Cu to the total concentration of Cu and Mn is 0.83 or more and less than 1. Claim 1, wherein the etching rate is 0.005 μm/hr or less when etched using a fluorine-based etching solution containing hydrogen fluoride at a concentration of 4.32 mol/L and ammonium fluoride at a concentration of 10.67 mol/L. 4. The laminated substrate with a piezoelectric thin film according to any one of 1 to 3. A step of preparing a sputtering target material composed of a sintered body represented by a composition formula (K _1−x Na _x )NbO ₃ (0<x<1);
Using the sputtering target material, an alkali niobium oxide having a perovskite structure represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1) is formed on the substrate, and the (001) plane orientation is It has a preferential orientation, contains Cu and Mn, has a total concentration of Cu and Mn of 0.2 at% or more and 0.6 at% or less, and has a ratio of the concentration of Cu to the total concentration of Cu and Mn of more than 0 and less than 1 a step of forming a piezoelectric thin film;
A method for manufacturing a laminated substrate with a piezoelectric thin film, comprising: a lower electrode film, a piezoelectric thin film formed on the lower electrode film, and an upper electrode film formed on the piezoelectric thin film;
The piezoelectric thin film is
Composed of an alkali niobium oxide having a perovskite structure represented by the composition formula (K 1- _x Na _x )NbO ₃ (0<x<1), preferentially oriented in the (001) plane orientation, and containing Cu and Mn ,
The total concentration of Cu and Mn is 0.2 at% or more and 0.6 at% or less,
The ratio of the concentration of Cu to the total concentration of Cu and Mn is more than 0 and less than 1,
Piezoelectric thin film element. A sintered body represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1),
containing Cu and Mn,
The total concentration of Cu and Mn is 0.2 at% or more and 0.6 at% or less,
The ratio of the concentration of Cu to the total concentration of Cu and Mn is more than 0 and less than 1,
Made of an alkali niobium oxide having a perovskite structure represented by the above composition formula, preferentially oriented in the (001) plane orientation, containing Cu and Mn, and having a total concentration of 0.2 at % or more and 0.6 at % or less, and the ratio of the concentration of Cu to the total concentration of Cu and Mn is more than 0 and less than 1. A sputtering target material for obtaining a piezoelectric thin film. A sputtering target material comprising a sintered body represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1),
Substrate temperature is 600° C., discharge power is 2200 W, introduced gas is a mixed gas of Ar gas and O ₂ gas, atmospheric pressure is 0.3 Pa, Ar gas partial pressure/O ₂ gas partial pressure = 25/1, deposition rate is 1 μm/hr, when used as a target material for film formation on a substrate by RF magnetron sputtering,
On the substrate, an alkaline niobium oxide having a perovskite structure represented by the composition formula, preferentially oriented in the (001) plane orientation, containing Cu and Mn, the total concentration of Cu and Mn being 0.2 atm % or more and 0.6 at % or less, and the ratio of the concentration of Cu to the total concentration of Cu and Mn is more than 0 and less than 1.
Sputtering target material. A powder of K carbonate, a powder of Na carbonate, a powder of Nb oxide, a powder of Cu metal element oxide, and a powder of Mn metal oxide are mixed. obtaining a mixture;
applying pressure to the mixture to mold and bake at a first temperature;
represented by the composition formula (K _1-x Na _x )NbO ₃ (0<x<1), containing Cu and Mn, having a total concentration of Cu and Mn of 0.2 at % or more and 0.6 at % or less; and the ratio of the concentration of Cu to the total concentration of Mn is more than 0 and less than 1, is made of an alkali niobium oxide with a perovskite structure represented by the composition formula, is preferentially oriented in the (001) plane orientation, and is made of Cu and Mn, the total concentration of Cu and Mn is 0.2 at% or more and 0.6 at% or less, and the ratio of the concentration of Cu to the total concentration of Cu and Mn is more than 0 and less than 1. A method for manufacturing a sputtering target material that obtains a solid body.

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