JP6502460B2 - Laminated substrate with piezoelectric thin film and piezoelectric thin film element - Google Patents

Description

  The present invention relates to a laminated substrate with a piezoelectric thin film, a piezoelectric thin film element, and a method of manufacturing the same.

Piezoelectric materials are widely used in functional electronic components such as sensors and actuators. As the material of the piezoelectric body, lead-based materials, in particular, ferroelectric PZT system represented by a composition formula _{Pb (Zr 1-x Ti x} ) O 3 has been widely used. The PZT-based piezoelectric material can be manufactured by a sintering method in which a plurality of oxides are sintered.

  In recent years, thin film formation and high performance of a piezoelectric body have been strongly demanded. However, when the thickness of the piezoelectric body produced by the sintering method approaches the size of crystal grains constituting the piezoelectric body, for example, 10 μm due to thinning, the characteristic deterioration becomes remarkable. Therefore, as a method to replace the sintering method, a new method to which a thin film technology such as a sputtering method is applied has been studied.

In addition, a PZT piezoelectric material contains about 60 to 70 wt% of lead, which is not preferable in terms of prevention of pollution and the like. At present, various lead-free piezoelectric materials are being studied, among them, alkali niobium oxides (potassium sodium niobate having a perovskite structure represented by the composition formula (K _1-x Na _x ) NbO ₃ , hereinafter, (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 leading 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 characteristics of a piezoelectric thin film formed using alkaline 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
Alkali 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,
There is provided a laminated substrate with a piezoelectric thin film comprising a metal element selected from the group consisting of Mn and Cu in a concentration of 0.2 at% or more and 0.6 at% or less.

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
Alkali 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,
The etching rate is 0.005 μm / hr or less when etching is performed using a fluorine-based etching solution containing hydrogen fluoride at 4.32 mol / L and ammonium fluoride at a concentration of 10.67 mol / L,
Provided is a laminated substrate with a piezoelectric thin film having a dielectric constant of 300 or more and 1,000 or less when measured under a condition of a frequency of 1 kHz.

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
Alkali 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,
Provided is a piezoelectric thin film element including 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.

According to yet another aspect of the invention,
Alkali 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;
Supplying a fluorine-based etching solution to the laminated substrate in a state where at least a part of the piezoelectric thin film is exposed, and etching at least a part of a portion of the laminated substrate excluding the piezoelectric thin film;
A method of manufacturing a piezoelectric thin film element is provided.

According to yet another aspect of the invention,
Alkali 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;
When supplying a fluorine-based etching solution to the insulating film formed on the piezoelectric thin film and etching a part of the insulating film to expose the surface of the piezoelectric thin film, the piezoelectric thin film acts as an etching stopper Controlling the end point of the etching of the insulating film by
A method of manufacturing a piezoelectric thin film element is provided.

  According to the present invention, it is possible to improve the film characteristics of a piezoelectric thin film formed by using an 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. It is a schematic block diagram which shows the crystal structure of potassium sodium niobate. It is a schematic block diagram of the piezoelectric thin film device in one embodiment of the present invention. It is a figure which shows 1 process of the manufacturing process of the piezoelectric thin film element in one Embodiment of this invention. It is a figure which shows 1 process of the manufacturing process of the piezoelectric thin film element in one Embodiment of this invention. It is a figure which shows 1 process of the manufacturing process of the piezoelectric thin film element in one Embodiment of this invention. (A) is a figure which shows the evaluation result regarding the etching tolerance of a piezoelectric thin film, (b) shows the evaluation result regarding the insulation of a piezoelectric thin film, (c) shows the evaluation regarding the dielectric constant of a piezoelectric thin film.

First Embodiment
Hereinafter, an embodiment of the present invention will be described.

(1) Configuration of Laminated Substrate As shown in FIG. 1, the laminated substrate 10 of the present embodiment is deposited on a substrate 1, a lower electrode film 2 deposited on the substrate 1, and a lower electrode film 2. It is configured as a laminate including the piezoelectric thin film 3 and the 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, ie, a Si substrate with a surface oxide film It can be used suitably. In addition, as the substrate 1, it is also possible to use a Si substrate 1 a whose surface has an exposed Si (100) surface, Si (111) surface, etc. In addition, as the substrate 1, a metal substrate made of an SOI (Silicon On Insulator) substrate, a quartz glass (SiO ₂ ) substrate, a gallium arsenide (GaAs) substrate, a sapphire (Al ₂ O ₃ ) substrate, stainless steel or the like can 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, for example, using platinum (Pt). The lower electrode film 2 is a single crystal film or a polycrystalline film (hereinafter, these are also referred to as a Pt film). The crystals constituting the Pt film are preferably preferentially oriented in the (111) plane direction with respect to the surface of the substrate 1. That is, it is preferable that the surface of the Pt film (the surface to be the base of the piezoelectric thin film 3) be mainly composed of a Pt (111) surface. The Pt film can be formed using a method such as a sputtering method or an evaporation method. The lower electrode film 2 may be made of various metals such as gold (Au), ruthenium (Ru), iridium (Ir) and the like, alloys containing these as main components other than Pt, strontium ruthenate (SrRuO ₃ ), lanthanum nickelate (LaNiO) It is also possible to form a film using a metal oxide such as ₃ ). Between the substrate 1 and the lower electrode film 2, for example, titanium (Ti), tantalum (Ta), titanium oxide (TiO ₂ ), nickel (Ni) or the like as a main component in order to enhance the adhesion thereof. An adhesion layer 6 is provided. The adhesion layer 6 can be formed into a film using methods, such as sputtering method and 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), niobium (Nb), and an alkali niobium oxide represented by a composition formula (K _1-x Na _x ) NbO ₃ , that is, potassium niobate It is possible to form a membrane using sodium (KNN). The coefficient x [= Na / (K + Na)] in the above composition formula is in the range of 0 <x <1, preferably 0.4 ≦ x ≦ 0.7. The piezoelectric thin film 3 is a polycrystalline film of KNN (hereinafter also referred to as a KNN thin film). The crystal structure of KNN is a perovskite structure as shown in FIG. The crystals constituting the KNN thin film are preferably 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 to be the base of the upper electrode film 4) be mainly composed of the KNN (001) surface. By directly depositing a KNN thin film on a Pt film preferentially oriented in the (111) plane orientation with respect to the surface of the substrate 1, crystals constituting the KNN thin film are made to the (001) plane with respect to the surface of the substrate 1. It is possible to preferentially orient in the azimuth. For example, 80% or more of the crystal groups constituting the KNN thin film are 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 a method such as a sputtering method, a PLD (Pulsed Laser Deposition) method, a sol-gel method, or the like. 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 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, for example, using various metals such as Pt, Au, aluminum (Al), Cu, etc., and alloys thereof. The upper electrode film 4 can be formed using a method such as a sputtering method, an evaporation method, a plating method, a metal paste method or the like. The upper electrode film 4 does not significantly affect the crystal structure of the piezoelectric thin film 3 as the lower electrode film 2 does. Therefore, the material, the crystal structure, and the film formation method of the upper electrode film 4 are not particularly limited. In order to enhance the adhesion 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. The thickness of the upper electrode film 4 can be, for example, 100 to 1000 nm, and when the adhesion layer is provided, the thickness 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 in the present embodiment. The piezoelectric thin film device 30 includes at least a piezoelectric thin film element 20 obtained by forming the above-described laminated substrate 10 into a predetermined shape, and a voltage detection means 11 a or a voltage application means 11 b connected to the piezoelectric thin film element 20. Configured

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

  By connecting the voltage application unit 11 b 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. The piezoelectric thin film 3 can be deformed by applying a voltage between the lower electrode film 2 and the upper electrode film 4 by the voltage application means 11 b. By this deformation operation, various members connected to the piezoelectric thin film device 30 can be operated. In this case, examples of applications of the piezoelectric thin film device 30 include a head for an ink jet printer, a MEMS mirror for a scanner, and a vibrator for an ultrasonic wave generator.

(3) Addition of Mn and Cu to Piezoelectric Thin Film As described above, the piezoelectric thin film 3 in the present embodiment is 0.2 at% or more and 0.6 at% or less of a metal element selected from the group consisting of Mn and Cu. Contains at concentrations within the range of
Hereinafter, the effects obtained by this will be described.

(A) By adding Mn or Cu to the piezoelectric thin film 3 at a concentration within the above range, the insulation (leak resistance) of the piezoelectric thin film 3 can be improved. 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, an electric field of 25 × 10 ⁶ V / m is applied to the piezoelectric thin film 3 in the thickness direction. The leak current density can be 500 μA / cm ² or less, preferably 300 μA / cm ² or less. Further, for example, even when the Mn concentration in the piezoelectric thin film 3 is 0.2 at% or more and 0.6 at% or less, the same insulating properties as in the case where the Cu concentration in the piezoelectric thin film 3 is in the above range can be obtained. It becomes possible. By improving the insulation of the piezoelectric thin film 3, the performance of the piezoelectric thin film device 30 such as a sensor or an actuator manufactured by processing the above-described laminated substrate 10 can be enhanced.

(B) Adding Cu to the piezoelectric thin film 3 at a concentration within the above range makes it possible to improve the resistance to a fluorine-based etching solution, that is, the etching resistance, in addition to the above-described insulation. 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. When the piezoelectric thin film 3 is immersed in a buffered hydrofluoric acid (BHF) solution containing a concentration of / L, the etching rate of the piezoelectric thin film 3 can be made 0.005 μm / hr or less. When the present inventors supplied the BHF solution to the piezoelectric thin film 3 under the above-mentioned conditions, it has been confirmed that the etching of the piezoelectric thin film 3 does not proceed even after 60 minutes.

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

  For example, as shown in FIG. 5A, a substrate 1 having surface oxide films 1b and 1c formed respectively on the front and back surfaces of a single crystal Si substrate 1a is prepared, and an adhesion layer is formed on the surface oxide film 1b on the surface side. 6. A process after manufacturing the laminated substrate 10 by forming the lower electrode film 2 and the piezoelectric thin film 3 in this order will be considered. In this case, as shown in FIG. 5B, a process of etching the surface electrode film 1c on the back side may be performed using a BHF solution or the like. When performing this processing, by increasing the etching resistance of the piezoelectric thin film 3 as described above, there is no need to form a protective film for protecting the exposed surface 3 a of the piezoelectric thin film 3, and the processing process can be simplified. It becomes possible.

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. The laminated substrate 10 is prepared by forming the adhesion layer 6, the lower electrode layer 2 and the piezoelectric thin film 3 in this order on the surface oxide film 1b, and then forming a single crystal Si substrate 1a. Consider the processing after the part is removed by Deep-RIE or wet etching. In this case, as shown in FIG. 6B, processing may be performed to remove a part of the BOX layer 1e left behind on the back surface side of the Si layer 1f using a BHF solution or the like. Also when performing this processing, by increasing the etching resistance of the piezoelectric thin film 3 as described above, it is not necessary to form a protective film for protecting the exposed surface 3a of the piezoelectric thin film 3, and the processing process is simplified. It becomes possible.

Also, for example, as shown in FIG. 7A, the processing after forming the insulating film (SiO ₂ film) 7 and the etching mask 7m in this order on the piezoelectric thin film 3 after patterning will be considered. In this case, as shown in FIG. 7B, in order to expose the film formation 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, the piezoelectric thin film 3 can be made to function as an etching stopper by enhancing the etching resistance of the piezoelectric thin film 3 which is the base of the insulating film 7 as described above, and the end point of the etching process is accurately controlled. It becomes possible. Further, a BHF solution or the like having a stronger etching power than an etching gas such as hydrogen fluoride (HF) gas can be used as an etchant, and the efficiency of the etching process can be enhanced. In addition, even when wet etching is performed using a BHF solution or the like, it is possible to suppress the etching damage of the piezoelectric thin film 3 accompanying the etching process.

  The effect of improving the etching resistance described above can be obtained particularly remarkably when Cu is added to the piezoelectric thin film 3, but is difficult to obtain when Mn is added to the piezoelectric thin film 3. By utilizing this characteristic, it is also possible to appropriately finely adjust the etching resistance of the piezoelectric thin film 3 while enhancing the insulation of the piezoelectric thin film 3. For example, by adding both Mn and Cu to the piezoelectric thin film 3 at a concentration within the above range, the ratio of the Cu concentration to the total concentration of Mn and Cu (Cu / Mn + Cu) approaches 1 to make the piezoelectric thin film 3 It is possible to control to enhance the etching resistance while enhancing the insulation as described above. Further, for example, by bringing the above ratio (Cu / Mn + Cu) close to 0, it is possible to control so as to appropriately suppress the increase in etching resistance 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 above range, the relative dielectric constant of the piezoelectric thin film 3 can be made 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 relative dielectric constant of the piezoelectric thin film 3 measured under the conditions of 1 kHz frequency and ± 1 V is 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 set to 1000 or less.

(D) As described above, by adding Mn or Cu to the piezoelectric thin film 3 in the above-described concentration range, the film characteristics of the piezoelectric thin film 3 can be improved. That is, the insulation of the piezoelectric thin film 3 can be enhanced, and the relative dielectric constant of the piezoelectric thin film 3 can be made to have an appropriate size. In addition to the above-described effects, the etching resistance of the piezoelectric thin film 3 can be enhanced by adding Cu to the piezoelectric thin film 3 in the above-described concentration range. Further, by adding both Mn and Cu to the piezoelectric thin film 3 in the above-described concentration range, it is possible to appropriately finely adjust the etching resistance of the piezoelectric thin film 3 while obtaining the above-described effect.

  In order to obtain the above effects simultaneously in a balanced manner, the concentration of Mn and Cu in the piezoelectric thin film 3 needs to be 0.2 at% or more and 0.6 at% or less. As described later, when the total concentration of Mn and Cu in the piezoelectric thin film 3 is less than 0.2 at%, the above-described effect on the insulation may not be obtained. When the Cu concentration in the piezoelectric thin film 3 is less than 0.2 at%, the above-described effect on the etching resistance may not be obtained. In addition, when the total concentration of Mn and Cu in the piezoelectric thin film 3 exceeds 0.6 at%, the relative dielectric constant of the piezoelectric thin film 3 becomes excessive, causing a decrease in sensitivity when applied to a sensor, or applied to an actuator When this happens, it may cause an increase in power consumption. This is considered to be one of the reasons that it is difficult to preferentially orient the crystal constituting the piezoelectric thin film 3 with respect to the surface of the substrate 1 in the (001) plane orientation as the addition amount of Mn and Cu increases. Be

(4) Modifications The present embodiment is not limited to the above-described aspect, and may be modified as follows, for example.

  For example, the concentration of Mu or Cu in the piezoelectric thin film 3 may be 0.2 at% or more and 0.25% or less. In this case, it is possible to lower the relative dielectric constant of the piezoelectric thin film 3 within the above-described range while obtaining the above-described effects on the insulating property and the etching resistance. For example, it is possible to set the relative dielectric constant of the piezoelectric thin film 3 measured under the conditions of frequency 1 kHz and ± 1 V to a size within the range of 300 to 400. The multilayer substrate 10 configured in this way can be particularly suitably used in applications such as high sensitivity sensors where a low dielectric constant is required.

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 insulation of the piezoelectric thin film 3 can be further enhanced while obtaining the above-described effects on the insulation and the etching resistance. For example, when an electric field of 25 × 10 ⁶ V / m is applied to the piezoelectric thin film 3 in the thickness direction, the leak current density can be 500 μA / cm ² or less. The multilayer substrate 10 configured in this manner can be particularly suitably used for applications such as actuators that require high withstand voltage.

  Also, 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 on the insulation property and the relative dielectric constant. For example, the etching rate of the piezoelectric thin film 3 when immersing the piezoelectric thin film 3 in the BHF solution having the above-mentioned concentration can be set to 0.005 μm / hr or less.

Second Embodiment
As in the first embodiment, addition of Mn and Cu to the piezoelectric thin film 3 is performed, and further, the out-of-plane direction lattice constant c of the crystal forming the piezoelectric thin film 3, ie, the alkali niobium oxide and the in-plane direction lattice The ratio c / a to the constant a may be controlled as follows.

For example, the lattice constant ratio is set so that the ratio of the out-of-plane direction lattice constant c of the crystal constituting the piezoelectric thin film 3 to the in-plane direction lattice constant a is in the range of 0.98 ≦ c / a ≦ 1.01. You may control. Also in this case, the same effect as that of the first embodiment can be obtained. Further, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies | d ₃₁ | ≧ 90 pm / V, and the piezoelectric characteristics can be improved.

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

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

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

The c / a ratio described above 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 film formation. Although an Ar / O ₂ mixed gas is used as an atmosphere gas at the time of film formation by sputtering, moisture present in the chamber may be mixed with the atmosphere gas although the proportion thereof is very small. The c / a ratio of the KNN thin film largely depends on the orientation condition of the (001) plane orientation of the KNN thin film, and the c / a ratio becomes large in the (001) high orientation, and c in the (001) low orientation. The / a ratio tends to be smaller. The KNN thin film (001) orientation situation depends largely on in _{H 2} O partial pressure contained in the ambient gas during sputtering film formation, when _{H 2} O partial pressure is high becomes low orientation _{(001), H} 2 O 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 atmosphere gas, the c / a ratio of the KNN thin film can be controlled.

Third Embodiment
While adding Mn and Cu to the piezoelectric thin film 3 as in the first embodiment, the composition ratio of the material constituting the piezoelectric thin film 3, that is, the alkali niobium oxide is further controlled as follows. It is also good.

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

For example, the piezoelectric thin film 3 is represented by a composition formula (K _1-x Na _x ) _y NbO ₃ and has a perovskite structure in the range of 0.4 ≦ x ≦ 0.7 and 0.75 ≦ y ≦ 0.90. The film may be formed using an alkali niobium oxide of Also in this case, the same effect as that of the first embodiment can be obtained. In addition, the absolute value of the piezoelectric constant of the piezoelectric thin film 3 satisfies | d ₃₁ | 100100 pm / V, and the piezoelectric characteristics can be improved. In addition, the insulation resistance of the piezoelectric thin film can be more reliably improved. For example, it is also possible to set the leak current density which flows when an electric field of 50 kV / cm is applied in the thickness direction of the piezoelectric thin film to 0.1 μA / cm ² or less.

Note that the above-described 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 or the like and baking. 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 or the like.

Fourth Embodiment
While the addition of Mn and Cu into the piezoelectric thin film 3 is performed as in the first embodiment, the composition ratio of the material constituting the piezoelectric thin film 3 and the out-of-plane directional lattice constant c and the in-plane directional lattice constant a The ratio c / a to c may be controlled as follows.

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

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

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

Fifth Embodiment
While the addition of Mn and Cu into the piezoelectric thin film 3 is performed as in the first embodiment, the concentrations of carbon (C) and hydrogen (H) in the piezoelectric thin film 3 are further controlled as follows, respectively. It is also good.

For example, the C concentration in the piezoelectric thin film 3 when measured using SIMS may be 2 × 10 ¹⁹ cm ⁻³ or less, or the H concentration may be 4 × 10 ¹⁹ cm ⁻³ or less. Also in these cases, the same effect as that of the first embodiment can be obtained. In addition, the insulation resistance of the piezoelectric thin film 3 can be more reliably improved. For example, it is also possible to set the leak current density which flows when an electric field of 50 kV / cm is applied in the thickness direction of the piezoelectric thin film 3 to 0.1 μA / cm ² or less. Further, 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 that of the first embodiment can be obtained. In addition, the insulation resistance of the piezoelectric thin film 3 can be more reliably improved. For example, it is possible to set the leak current density which flows when an electric field of 50 kV / cm is applied in the thickness direction of the piezoelectric thin film 3 to 0.1 μA / cm ² or less. Further, 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 the H concentration in the piezoelectric thin film 3, it is effective to reduce the C concentration and the H concentration in the KNN sintered compact target used in sputtering. It is possible to reduce the C concentration and the H concentration in the sinter target as the firing temperature at the time of producing the sinter target is increased. In addition, it is also effective to increase the ratio of O ₂ in an atmosphere gas at the time of performing the sputtering film formation process, for example, a mixed gas of Ar gas and O ₂ gas. Further, it is also effective to perform heat treatment in the air or oxygen atmosphere after forming the piezoelectric thin film 3.

Sixth Embodiment
As shown in FIG. 2, it is also possible to use, as the substrate 1, a Si substrate 1 a on the surface of which an insulating film 1 d made of an insulating material other than SiO ₂ is formed. 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 in each of the embodiments described above By performing control as described above, the same effects as those of the embodiments and the like can be obtained. An adhesion layer may be provided between the piezoelectric thin film 3 and the upper electrode film 4 in the same manner as in the first embodiment.

Other Embodiments
The embodiments of the present invention have been specifically described above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the first to sixth embodiments described above can be implemented in combination as appropriate.

  Hereinafter, the experimental result which supports the effect of the above-mentioned embodiment is explained.

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

The film formation of the Ti layer, the Pt film, and the KNN thin film was all performed by the RF magnetron sputtering method. The processing conditions for forming the Ti layer and the Pt film were a substrate temperature of 300 ° C., a discharge power of 1200 W, an introduced gas Ar, a pressure of 0.3 Pa for Ar atmosphere, and a film forming time of 5 minutes. The processing conditions for forming the KNN thin film are substrate temperature 600 ° C., discharge power 2200 W, introduced gas Ar + O ₂ , pressure 0.3 Pa of Ar + O ₂ mixed atmosphere (partial pressure ratio Ar / O ₂ = 25/1), film formation The speed was 1 μm / hr.

The sputtering target material for forming a KNN thin film to which Cu is added has a composition of (K + Na) /Nb=0.8 to 1.2 and Na / (K + Na) = 0.4 to 0.7. And a sintered body of (K _1-x Na _x ) _y NbO ₃ containing Cu at a concentration of 0.2 at% or more and 0.6 at% or less. The target material is a mixture of K ₂ CO ₃ powder, Na ₂ CO ₃ powder, Nb ₂ O ₅ powder, and CuO powder for 24 hours using a ball mill, pre-baked at 850 ° C. for 10 hours, and then again using a ball mill. After pulverizing and shaping | molding by the pressure of 200 Mpa, it produced by baking at 1080 degreeC. 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, and EDX (energy dispersive type X before film forming treatment) Measured by line spectroscopy. In the evaluation to be described later, as a sputtering target material for forming a KNN thin film to which Mn is added, the above-mentioned (K at a concentration of 0.2 at% or more and 0.6 at% or less instead of Cu) _{A 1-x} Na _x ) _y NbO ₃ sintered body was used. When producing a sintered body, MgO powder was used instead of CuO powder in the above-mentioned preparation procedure.

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

(Evaluation on etching resistance)
The evaluation of the etching resistance was performed by immersing the laminated substrate in the BHF solution with the surface of the KNN thin film exposed and measuring the time until the erosion of the KNN thin film surface was started. 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 having a Cu concentration of 0 at% in the film starts to be attacked in less than one minute after being immersed in the BHF solution. In the case of the KNN thin film in which the Cu concentration in the film is 0.1 at%, although the etching of the KNN thin film is relatively difficult to progress, it has been confirmed that the corrosion starts about 1 minute after immersion. In the case of a KNN thin film having a Cu concentration of 0.2 at% in the film, it was confirmed that surface erosion can be avoided at least for 15 minutes after immersion. In the case of a KNN thin film in which the Cu concentration in the film was 0.5 at%, it was confirmed that surface erosion can be avoided 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, and by setting the Cu concentration in the film to 0.5 at% or more, the KNN It has been confirmed that the etching resistance of the thin film can be further enhanced. In addition, it has been confirmed that the above-mentioned effect on the etching resistance is difficult to be obtained when Mn is added to the KNN thin film instead of Cu.

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

As shown in FIG. 8B, in the case of a KNN thin film in which the Cu concentration in the film is 0 at%, it is confirmed that a leakage current of 500 μA / cm ² flows by applying a voltage of 2 to 4 V in the film thickness direction. did it. Further, in the case of a KNN thin film having a Cu concentration of 0.1 at% in the film, it was confirmed that a leak current of 500 μA / cm ² flows by applying a voltage of 5 to 7 V in the film thickness direction.

On the other hand, in the case of a KNN thin film in which the Cu concentration in the film is 0.2 at%, it is necessary to apply a voltage of 30 to 34 V in the film thickness direction in order to flow a leakage current of 500 μA / cm ² did it. In addition, in the case of a KNN thin film in which the Cu concentration in the film is 0.25 at%, a leak current of 500 μA / cm ² or more is not observed even if a voltage of 50 V is applied in the film thickness direction. However, it could be confirmed that it was 300 μA / cm ² or less. In addition, in the case of a KNN thin film in which the Cu concentration in the film was 0.5 at% or more, it was confirmed that a leak current of 500 μA / cm ² or more was not 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 insulation of the KNN thin film can be dramatically improved, and the Cu concentration in the film is 0.25 at%, and further 0.5 at%. It could be confirmed that the insulating property of the KNN thin film can be further enhanced by setting it to at least%. In addition, it has been confirmed that the above-mentioned effect on the insulating property can be obtained similarly to the case of adding Cu to the KNN thin film even when Mn is added to the KNN thin film instead of Cu. The preferable concentration range of the Mn concentration in this case is the same as the concentration range of Cu described above.

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

  As shown in FIG. 8C, in the case of the KNN thin film in which the Cu concentration in the film is 0.7 at% or more, it was confirmed that the relative dielectric constant exceeds 1000. In addition, in the case of a KNN thin film in which the Cu concentration in the film is 0.6 at% or more, it was confirmed that the relative dielectric constant is less than 1000. In addition, it has been confirmed that the relative dielectric constant is less than 400 in the case of a KNN thin film in which the Cu concentration in the film is 0.25 at% or less.

  That is, by setting the Cu concentration in the KNN thin film to 0.6 at% or less, the relative dielectric constant of the KNN thin film can be made a size suitable for the application of the sensor or actuator, and the Cu concentration in the film can be It could be confirmed that the relative dielectric constant of the KNN thin film can be made to be a size suitable for the application of the high sensitivity sensor by setting it to 0.25 at% or less. In addition, it has been confirmed that the above-described effect on the relative dielectric constant can be obtained similarly to the case of adding Cu to the KNN thin film also when Mn is added to the KNN thin film instead of Cu. The preferable concentration range of the Mn concentration in this case is the same as the concentration range of Cu described above.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally stated.

(Supplementary Note 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
Alkali 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,
There is provided a laminated substrate with a piezoelectric thin film comprising a metal element selected from the group consisting of Mn and Cu in a concentration of 0.2 at% or more and 0.6 at% or less.

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

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

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

(Supplementary Note 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
Alkali 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,
The etching rate is 0.005 μm / hr or less when etching is performed using a fluorine-based etching solution containing hydrogen fluoride at 4.32 mol / L and ammonium fluoride at a concentration of 10.67 mol / L,
The leakage current density is 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.
Provided is a laminated substrate with a piezoelectric thin film having a relative dielectric constant of 300 or more and 1,000 or less when measured under a condition of a frequency of 1 kHz.

(Supplementary Note 6)
In addition, preferably, the laminate substrate with a piezoelectric thin film according to any one of appendices 1 to 5, is provided.
The ratio of the out-of-plane direction lattice constant c to the in-plane direction lattice constant a of the crystal (alkali niobium oxide) constituting the piezoelectric thin film is in 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)
Further preferably, the laminate substrate with a piezoelectric thin film according to Appendix 6 is provided.
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),
Among the plurality of layers, the ratio of the out-of-plane direction lattice constant c of the crystal (alkali niobium oxide) constituting at least the thickest layer to the in-plane direction lattice constant a is 0.98 ≦ c / a ≦ 1. It is in the range of 01.

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

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

(Supplementary Note 10)
Preferably, the laminate substrate with a piezoelectric thin film according to Appendix 6 or 7 is preferably,
A compressive stress is generated in the piezoelectric thin film, and the ratio of the out-of-plane directional lattice constant c of the crystal (alkali niobium oxide) constituting the piezoelectric thin film to the in-plane directional lattice constant a is 1.004 ≦ c / a ≦ 1. It is in the range of 010.

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

(Supplementary Note 12)
In addition, preferably, the laminate substrate with a piezoelectric thin film according to any one of appendices 1 to 5, is provided.
The piezoelectric thin film is
An alkaline niobium oxide of a perovskite structure represented by the composition formula (K _{1 -x} Na _x ) _y NbO ₃ and in the 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.

(Supplementary Note 13)
In addition, preferably, the laminate substrate with a piezoelectric thin film according to any one of appendices 1 to 5, is provided.
The piezoelectric thin film is
It consists of an alkali niobium oxide of the perovskite structure which is represented by the compositional formula (K _{1 -x} Na _x ) _y NbO ₃ and in the 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.

(Supplementary Note 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 alkaline niobium oxide of a perovskite structure represented by the composition formula (K _{1 -x} Na _x ) _y NbO ₃ and in the range of 0.4 ≦ x ≦ 0.7 and 0.77 ≦ y ≦ 0.90,
The ratio of the out-of-plane direction lattice constant c of the crystal (alkali niobium oxide) constituting the piezoelectric thin film to the in-plane direction lattice constant a is in the range of 0.98 ≦ c / a ≦ 1.008.

(Supplementary Note 15)
Preferably, the laminated substrate with a piezoelectric thin film according to appendix 14 is provided.
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),
Among the plurality of layers, the ratio of the out-of-plane direction lattice constant c of the crystal (alkali niobium oxide) constituting at least the thickest layer to the in-plane direction lattice constant a is 0.98 ≦ c / a ≦ 1. It is in the range of 008.

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

(Supplementary Note 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
Alkali 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,
Provided is a piezoelectric thin film element including 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.

(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
Alkali 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,
Provided is a piezoelectric thin film element including 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.

(Appendix 19)
According to yet another aspect of the invention,
Alkali 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;
In a state where at least a part of the piezoelectric thin film is exposed, a fluorine-based etching solution is supplied to the laminated substrate (without providing a protective film covering the exposed surface of the piezoelectric thin film), and Etching at least a part of the portion excluding the piezoelectric thin film;
A method of manufacturing a piezoelectric thin film element is provided.

(Supplementary Note 20)
According to yet another aspect of the invention,
Alkali 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;
When supplying a fluorine-based etching solution to the insulating film formed on the piezoelectric thin film and etching a part of the insulating film to expose the surface of the piezoelectric thin film, the piezoelectric thin film acts as an etching stopper Controlling the end point of the etching of the insulating film by
A method of manufacturing a piezoelectric thin film element is provided.

(Supplementary Note 21)
According to yet another aspect of the invention,
0.2 at% or more and 0.6 atm of a metal element composed of a sintered body represented by a composition formula (K _1-x Na _x ) NbO ₃ (0 <x <1) and selected from the group consisting of Mn and Cu A sputtering target material is provided which comprises a concentration of% or less.

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

(Supplementary Note 23)
Further preferably, the sputtering target material according to appendix 21 is
The concentration of the metal element in the sintered body is 0.5 at% or more and 0.6 at% or less.

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

1 substrate 2 lower electrode film 3 piezoelectric thin film 10 laminated substrate

Claims (12)

A substrate, an electrode film formed on the substrate, and a piezoelectric thin film formed on the electrode film;
The piezoelectric thin film is
Alkali 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,
Only contains a concentration of less than 0.2at% or more 0.6at% of Cu,
Leakage current density when applying an electric field of 25 × 10 ⁶ V / m is 500 μA / cm ² or less,
A laminated substrate with a piezoelectric thin film having a dielectric constant of 1000 or less when measured under a frequency of 1 kHz . The piezoelectric thin film contains Cu at a concentration of 0.25 at% or more and 0.6 at% or less,
25 × 10 ⁶ Leakage current density is 300μA / cm when an electric field of V / m is applied ² The laminated substrate with a piezoelectric thin film according to claim 1, which is the following. The laminated substrate with a piezoelectric thin film according to claim 1 or 2, wherein the piezoelectric thin film has a relative dielectric constant of 300 or more and 1000 or less when measured under a condition of a frequency of 1 kHz. The piezoelectric thin film contains Cu at a concentration of 0.5 at% to 0.6 at%,
50 × 10 ⁶ Leakage current density is 500μA / cm when an electric field of V / m is applied ² The laminated substrate with a piezoelectric thin film according to claim 1, which is the following. 5. The laminated substrate with a piezoelectric thin film according to claim 4, wherein the piezoelectric thin film has a relative dielectric constant of 700 or more and 1000 or less when measured under a condition of a frequency of 1 kHz. The piezoelectric thin film, a Mn, more than 0.2 at% 0. The laminated substrate with a piezoelectric thin film according to any one of claims 1 to 5, wherein the concentration is 4 at% or less , and the total concentration of Cu and Mn is 0.6 at% or less . The laminated film substrate with a piezoelectric thin film according to any one of claims 1 to 5 , wherein the piezoelectric thin film substantially does not contain Mn. 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
Alkali 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,
Only contains a concentration of less than 0.2at% or more 0.6at% of Cu,
Leakage current density when applying an electric field of 25 × 10 ⁶ V / m is 500 μA / cm ² or less,
Piezoelectric thin film element with a relative dielectric constant of 1000 or less when measured under the condition of 1 kHz frequency . The piezoelectric thin film contains Cu at a concentration of 0.25 at% or more and 0.6 at% or less,
25 × 10 ⁶ Leakage current density is 300μA / cm when an electric field of V / m is applied ² The piezoelectric thin film element according to claim 8, which is the following. The piezoelectric thin film contains Cu at a concentration of 0.5 at% to 0.6 at%,
50 × 10 ⁶ Leakage current density is 500μA / cm when an electric field of V / m is applied ² The laminated substrate with a piezoelectric thin film according to claim 8, which is the following. The piezoelectric thin film, a Mn, more than 0.2 at% 0. The piezoelectric thin film element according to any one of claims 8 to 10, wherein the concentration is 4 at% or less and the total concentration of Cu and Mn is 0.6 at% or less . The piezoelectric thin film element according to any one of claims 8 to 10 , wherein the piezoelectric thin film substantially does not contain Mn.