Substrate with PZT-based ferroelectric layer

Abstract

The present invention is provided with: a substrate (11); a silicon oxide layer (12) formed on at least the front surface of the substrate (11); an electrode layer (13) laminated on the silicon oxide layer (12); and a PZT-based ferroelectric layer (14) laminated on the electrode layer (13). The Pb content in the silicon oxide layer (12) is 1 atom% or less. Preferably, an insulating oxide layer (15) is formed between the silicon oxide layer (12) and the electrode layer (13). Preferably, a conductive oxide layer (16) is formed between the electrode layer (13) and the PZT-based ferroelectric layer (14).

Description

PZT-based ferroelectric layer substrate

[0001] The present invention relates to a substrate with a PZT-based ferroelectric layer, in which a PZT-based ferroelectric layer is formed on a substrate. This application claims priority based on Japanese Patent Application No. 2024-010956, filed on January 29, 2024, the contents of which are incorporated herein by reference.

[0002] PZT (lead zirconate titanate: PbZrTiO ３ ) is lead zirconate (PbZrO ３ ) and lead titanate (PbTiO ３ ) and has a large ferroelectricity at room temperature. Substrates with a PZT-based ferroelectric layer, in which a ferroelectric layer (PZT-based ferroelectric layer) made of the above-mentioned PZT-based ferroelectric is formed on a substrate, are used in composite electronic components such as thin-film capacitors, capacitors, IPDs, capacitors for DRAMs, multilayer capacitors, gate insulators for transistors, nonvolatile memories, current-collecting infrared detection elements, piezoelectric elements, electro-optical elements, actuators, resonators, ultrasonic motors, and LC noise filter elements.

[0003] When forming the above-mentioned PZT-based ferroelectric layer, a sol-gel method (also called a chemical solution deposition method (CSD method)) is used, as shown in, for example, Patent Document 1. The sol-gel method is a method in which a sol-gel liquid containing a PZT-based ferroelectric composition is applied onto an electrode, and the resulting applied film is heated to form a piezoelectric film.

[0004] Japanese Patent Application Publication No. 2013-211306 (A)

[0005] The above-mentioned PZT-based ferroelectric layer-equipped substrate has a laminated structure in which a silicon oxide layer is formed on the surface of the substrate, an electrode layer is formed on the silicon oxide layer, and a PZT-based ferroelectric layer is formed on the electrode layer. However, in the PZT-based ferroelectric layer-equipped substrate with the above-mentioned structure, a white haze-like phenomenon sometimes occurs. In such cases, there is a risk of deterioration in characteristics due to poor appearance, generation of leakage current, etc.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a substrate with a PZT-based ferroelectric layer that can suppress defects in appearance, the occurrence of leakage current, etc., and can be used stably.

[0007] In order to solve the above problem, the inventors conducted extensive research and found that, in a substrate with a PZT-based ferroelectric layer on which a white haze-like phenomenon was observed, irregularities were formed at the interface between the silicon oxide layer and the electrode layer. They then discovered that the cause of these irregularities was that Pb contained in the PZT-based ferroelectric layer diffused into the silicon oxide layer, causing part of the silicon oxide layer to turn into lead glass, resulting in the generation of voids.

[0008] The present invention has been made based on the above findings, and a substrate with a PZT-based ferroelectric layer according to a first aspect of the present invention comprises a substrate, a silicon oxide layer formed on at least a surface of the substrate, an electrode layer stacked on the silicon oxide layer, and a PZT-based ferroelectric layer stacked on the electrode layer, wherein the silicon oxide layer has a Pb content of 1 atomic % or less.

[0009] According to the substrate with a PZT-based ferroelectric layer of Aspect 1 of the present invention, the Pb content in the silicon oxide layer formed at least on the surface of the substrate is 1 atomic % or less. This prevents a part of the silicon oxide layer from becoming lead glass and forming voids, smoothing the interface between the silicon oxide layer and the electrode layer, preventing defects in appearance, the occurrence of leakage current, and the like, and allowing for stable use.

[0010] A substrate with a PZT-based ferroelectric layer according to a second aspect of the present invention is the substrate with a PZT-based ferroelectric layer according to the first aspect of the present invention, characterized in that an insulating oxide layer is formed between the silicon oxide layer and the electrode layer. According to the substrate with a PZT-based ferroelectric layer according to the second aspect of the present invention, since the insulating oxide layer is formed between the silicon oxide layer and the electrode layer, this insulating oxide layer acts as a Pb diffusion barrier layer, preventing the diffusion of Pb from the PZT-based ferroelectric layer into the silicon oxide layer, thereby further reducing the Pb content in the silicon oxide layer. Furthermore, the insulating oxide layer ensures insulation between the electrode layer and the silicon oxide layer.

[0011] A substrate with a PZT-based ferroelectric layer according to a third aspect of the present invention is the substrate with a PZT-based ferroelectric layer according to the second aspect of the present invention, wherein the insulating oxide layer is made of ZrO ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ layer, TiO ２ According to the substrate with a PZT-based ferroelectric layer of the third aspect of the present invention, the insulating oxide layer is at least one selected from the group consisting of ZrO ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ Since the layer is one or more selected from these ZrO ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ The layer prevents the diffusion of Pb from the PZT-based ferroelectric layer into the silicon oxide layer, and the Pb content in the silicon oxide layer can be further reduced. ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ The layer has excellent insulating properties, and can ensure sufficient insulation between the electrode layer and the silicon oxide layer.

[0012] A substrate with a PZT-based ferroelectric layer according to Aspect 4 of the present invention is characterized in that, in the substrate with a PZT-based ferroelectric layer according to Aspect 2 or Aspect 3 of the present invention, the thickness of the insulating oxide layer is within the range of 0.10 μm or more and 0.30 μm or less. According to the substrate with a PZT-based ferroelectric layer according to Aspect 4 of the present invention, the thickness of the insulating oxide layer is within the range of 0.10 μm or more and 0.30 μm or less, so that diffusion of Pb from the PZT-based ferroelectric layer to the silicon oxide layer is prevented, and the Pb content in the silicon oxide layer can be further reduced.

[0013] A substrate with a PZT-based ferroelectric layer according to Aspect 5 of the present invention is characterized in that, in the substrate with a PZT-based ferroelectric layer according to any one of Aspects 1 to 4 of the present invention, a conductive oxide layer is formed between the electrode layer and the PZT-based ferroelectric layer. According to the substrate with a PZT-based ferroelectric layer according to Aspect 5 of the present invention, since a conductive oxide layer is formed between the electrode layer and the PZT-based ferroelectric layer, the conductive oxide layer acts as a Pb diffusion barrier layer, preventing Pb from diffusing from the PZT-based ferroelectric layer to the silicon oxide layer, thereby further reducing the Pb content in the silicon oxide layer. Furthermore, since the conductive oxide layer is used, electrical conductivity between the electrode layer and the PZT-based ferroelectric layer can be sufficiently ensured.

[0014] A substrate with a PZT-based ferroelectric layer according to a sixth aspect of the present invention is the substrate with a PZT-based ferroelectric layer according to the fifth aspect of the present invention, characterized in that the conductive oxide layer is at least one selected from a RuO layer, a LaNiO layer, a SnO layer, and a ZnO layer. According to the substrate with a PZT-based ferroelectric layer according to the sixth aspect of the present invention, the conductive oxide layer is at least one selected from a RuO layer, a LaNiO layer, a SnO layer, and a ZnO layer. Therefore, the conductive oxide layer reliably functions as a Pb diffusion barrier layer, preventing Pb from diffusing from the PZT-based ferroelectric layer to the silicon oxide layer, thereby further reducing the Pb content in the silicon oxide layer. Furthermore, the conductive oxide layer has sufficiently excellent conductivity, ensuring sufficient electrical conductivity between the electrode layer and the PZT-based ferroelectric layer.

[0015] A substrate with a PZT-based ferroelectric layer according to Aspect 7 of the present invention is characterized in that, in the substrate with a PZT-based ferroelectric layer according to Aspect 5 or Aspect 6 of the present invention, the thickness of the conductive oxide layer is in the range of 0.05 μm or more and 0.20 μm or less. According to the substrate with a PZT-based ferroelectric layer according to Aspect 7 of the present invention, the thickness of the conductive oxide layer is in the range of 0.05 μm or more and 0.20 μm or less, so that diffusion of Pb from the PZT-based ferroelectric layer to the silicon oxide layer is prevented, and the Pb content in the silicon oxide layer can be further reduced.

[0016] According to the present invention, it is possible to provide a substrate with a PZT-based ferroelectric layer that can suppress defects in appearance, the occurrence of leakage current, etc., and can be used stably.

[0017] 1 is a cross-sectional view illustrating an example of a substrate with a PZT-based ferroelectric layer according to an embodiment of the present invention, and FIG. 2 is a flow chart illustrating a method for manufacturing a substrate with a PZT-based ferroelectric layer according to an embodiment of the present invention.

[0018] The following describes a substrate with a PZT-based ferroelectric layer according to an embodiment of the present invention, which is used in composite electronic components such as thin film capacitors, capacitors, IPDs, capacitors for DRAMs, multilayer capacitors, gate insulators for transistors, nonvolatile memories, current collection type infrared detectors, piezoelectric elements, electro-optical elements, actuators, resonators, ultrasonic motors, and LC noise filter elements.

[0019] As shown in FIG. 1 , the substrate 10 with a PZT-based ferroelectric layer according to this embodiment includes a substrate 11, a silicon oxide layer 12 formed on at least the surface of the substrate 11, an electrode layer 13 formed on the silicon oxide layer 12, and a PZT-based ferroelectric layer 14 formed on the electrode layer 13. In the substrate 10 with a PZT-based ferroelectric layer according to this embodiment, the Pb content in the silicon oxide layer 12 is 1 atomic % or less. Although not particularly limited, the Pb content may be 0.01 atomic % or more. The Pb content in the silicon oxide layer can be measured by performing depth profile analysis of the substrate with a PZT-based ferroelectric layer using XPS. For example, XPS measurement and surface cutting by argon sputtering can be repeated to calculate the Pb content in atomic % from the ratio to other elements. For example, the sputtering rate can be adjusted by SiO ２ The Pb content can be obtained as the average value of the Pb content measured 32 times (a total of 32 minutes, approximately 204.8 nm) starting from the point where the Si content is 5% or more, with a conversion rate of 6.4 nm / min. This method can be used both when the insulating oxide layer 15 described below is not present and when it is present. When the insulating oxide layer 15 is not present between the silicon oxide layer 12 and the electrode layer 13, the Pb content can be obtained as the average value of the Pb content by the following method instead of the above method. That is, the measurement start point is set to a point where the Pt content of the electrode layer is 10 atomic % or less, and the Pb content can be obtained as the average value of the Pb content by the same method as above.

[0020] In the substrate 10 with a PZT-based ferroelectric layer according to this embodiment, it is preferable that an insulating oxide layer 15 is formed between the silicon oxide layer 12 and the electrode layer 13, as shown in Fig. 1. Furthermore, in the substrate 10 with a PZT-based ferroelectric layer according to this embodiment, it is preferable that a conductive oxide layer 16 is formed between the electrode layer 13 and the PZT-based ferroelectric layer 14, as shown in Fig. 1.

[0021] The substrate 11 may be, for example, a silicon substrate, a stainless steel substrate, an alumina substrate, or the like. The thickness t1 of the substrate 11 is not particularly limited, but is preferably within the range of 500 μm to 1000 μm. In the substrate 10 with a PZT-based ferroelectric layer according to this embodiment, the substrate 11 is a silicon substrate.

[0022] The silicon oxide layer 12 formed on the surface of the substrate 11 is, for example, SiO ２ The silicon oxide layer 12 is preferably made of silicon oxide such as silicon dioxide. The thickness t2 of the silicon oxide layer 12 is preferably 0.2 μm or more, and more preferably 0.4 μm or more. The thickness t2 of the silicon oxide layer 12 is preferably 1.0 μm or less, and more preferably 0.7 μm or less. In this embodiment, since a silicon substrate is used as the substrate 11, the silicon oxide layer 12 is formed by thermally oxidizing the surface of the substrate 11 (silicon substrate), as will be described later.

[0023] The electrode layer 13 is made of a metal having excellent conductivity, and in this embodiment, is made of Pt (platinum), which has excellent conductivity and is chemically stable. There are no particular restrictions on the thickness t3 of the electrode layer 13, but it is preferably in the range of 0.1 μm to 0.3 μm.

[0024] The PZT-based ferroelectric layer 14 is made of PZT (lead zirconate titanate: PbZrTiO ３ ), but also includes those made of PZT-based dielectrics such as PLZT, PMnZT, and PNbZT, and has excellent dielectric properties. The thickness t4 of this PZT-based ferroelectric layer 14 is preferably 0.4 μm or more, and more preferably 0.5 μm or more. The thickness t4 of the PZT-based ferroelectric layer 14 is preferably 3.0 μm or less, and more preferably 2.5 μm or less.

[0025] The insulating oxide layer 15 formed between the silicon oxide layer 12 and the electrode layer 13 acts as a diffusion prevention layer and suppresses the diffusion of Pb contained in the PZT-based ferroelectric layer 14 into the silicon oxide layer 12. Since the insulating oxide layer 15 is made of oxide, it is possible to suppress the influence on the PZT-based ferroelectric layer 14. Furthermore, since the insulating oxide layer 15 has excellent insulating properties, it is possible to ensure insulation between the electrode layer 13 and the silicon oxide layer 12.

[0026] In this embodiment, the insulating oxide layer 15 is made of ZrO ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ It is preferable that the thickness t5 of the insulating oxide layer 15 be at least one selected from the group consisting of silicon oxide layer, silicon dioxide layer, silicon dioxide film ...

[0027] The conductive oxide layer 16 formed between the electrode layer 13 and the PZT-based ferroelectric layer 14 has the effect of suppressing the diffusion of Pb contained in the PZT-based ferroelectric layer 14 into the silicon oxide layer 12 and ensuring electrical conductivity between the electrode layer 13 and the PZT-based ferroelectric layer 14. In this embodiment, the conductive oxide layer 16 is preferably one or more selected from a RuO layer, a LaNiO layer, a SnO layer, and a ZnO layer. These conductive oxide layers are particularly suitable as the conductive oxide layer 16 formed between the electrode layer 13 and the PZT-based ferroelectric layer 14 because they can efficiently prevent the diffusion of Pb and have excellent electrical conductivity. The thickness t6 of the conductive oxide layer 16 is preferably 0.05 μm or more, and more preferably 0.10 μm or more. The thickness t6 of the conductive oxide layer 16 is preferably 0.30 μm or less, and more preferably 0.20 μm or less.

[0028] Next, a method for manufacturing the substrate 10 with a PZT-based ferroelectric layer according to this embodiment will be described with reference to Fig. 2. As shown in Fig. 1, the method for manufacturing the substrate 10 with a PZT-based ferroelectric layer according to this embodiment includes a silicon oxide layer forming step S01, an insulating oxide layer forming step S02, an electrode layer forming step S03, a conductive oxide layer forming step S04, and a PZT-based ferroelectric layer forming step S05.

[0029] In the silicon oxide layer forming step S01, a silicon oxide layer 12 is formed on the surface of the substrate 11. In this embodiment, since the substrate 11 is a silicon substrate, the silicon oxide layer 12 is formed by thermally oxidizing the surface of the substrate 11 (silicon substrate).

[0030] In the insulating oxide layer forming step S02, the insulating oxide layer 15 is formed by a sol-gel method. In the electrode layer forming step S03, the electrode layer 13 is formed by a sputtering method using a sputtering target made of a metal with excellent conductivity (Pt in this embodiment). In the conductive oxide layer forming step S04, the insulating oxide layer 15 is formed by a sol-gel method. Here, the insulating oxide layer forming step S02, the electrode layer forming step S03, and the conductive oxide layer forming step S04 may be performed consecutively by changing the target in the sputtering apparatus.

[0031] In the PZT-based ferroelectric layer forming step S05, the PZT-based ferroelectric layer 14 is formed by a sol-gel method. A PZT-based sol-gel liquid containing a plurality of oxides that constitute the PZT-based ferroelectric layer is applied onto the conductive oxide layer 16, and the resulting applied film is heated and baked in an oxidizing atmosphere, thereby forming the PZT-based ferroelectric layer 14.

[0032] The PZT-based sol-gel liquid is a liquid that generates a PZT-based ferroelectric when heated in an oxidizing atmosphere. Spin coating or dipping can be used as a method for applying this PZT-based sol-gel liquid. Furthermore, when the applied film is heated and baked in an oxidizing atmosphere, the baking temperature is preferably in the range of 600°C to 800°C, and the holding time at the baking temperature is preferably in the range of 30 seconds to 5 minutes. In the PZT-based ferroelectric layer forming step S05, the step of applying the PZT-based sol-gel liquid and the step of heating the resulting applied film in an oxidizing atmosphere may be repeated until a PZT-based ferroelectric layer 14 of the desired thickness is obtained.

[0033] Here, when the PZT-based sol-gel liquid is baked at a high temperature of 600° C. or higher, there is a risk that Pb contained in the PZT-based sol-gel liquid will diffuse into the silicon oxide layer 12 through the grain boundaries of the electrode layer 13. In this embodiment, the insulating oxide layer 15 and the conductive oxide layer 16 are formed, so that the diffusion of Pb into the silicon oxide layer 12 is suppressed.

[0034] Through the steps described above, the substrate 10 with the PZT-based ferroelectric layer according to this embodiment is manufactured.

[0035] In the substrate 10 with a PZT-based ferroelectric layer according to the present embodiment having the above-described configuration, the silicon oxide layer 12 formed on at least the surface of the substrate 11 has a Pb content of 1 atomic % or less. This prevents a portion of the silicon oxide layer 12 from becoming lead glass and forming voids, smoothing the interface between the silicon oxide layer 12 and the electrode layer 13, thereby preventing defects in appearance, the occurrence of leakage current, and the like, and enabling stable use.

[0036] In this embodiment, when the insulating oxide layer 15 is formed between the silicon oxide layer 12 and the electrode layer 13, the insulating oxide layer 15 prevents the diffusion of Pb from the PZT-based ferroelectric layer 14 to the silicon oxide layer 12, and the Pb content in the silicon oxide layer 12 can be further reduced. ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ layer, TiO ２ When any one or more selected from the ZrO layer is used, the diffusion of Pb into the silicon oxide layer 12 is prevented, and the Pb content in the silicon oxide layer 12 can be further reduced. ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ layer, TiO ２ The insulating oxide layer 15 has excellent insulating properties and can ensure insulation between the electrode layer 13 and the silicon oxide layer 12. When the thickness of the insulating oxide layer 15 is in the range of 0.10 μm to 0.30 μm, the diffusion of Pb into the silicon oxide layer 12 is prevented, and the Pb content in the silicon oxide layer 12 can be further reduced.

[0037] In this embodiment, when the conductive oxide layer 16 is formed between the electrode layer 13 and the PZT-based ferroelectric layer 14, the conductive oxide layer 16 acts as a Pb diffusion prevention layer, preventing the diffusion of Pb from the PZT-based ferroelectric layer 14 to the silicon oxide layer 12, thereby further reducing the Pb content in the silicon oxide layer 12. In addition, since the conductive oxide layer 16 is made of a conductive oxide, electrical conductivity between the electrode layer 13 and the PZT-based ferroelectric layer 14 can be sufficiently ensured.

[0038] In particular, when the conductive oxide layer 16 is one or more selected from a RuO layer, a LaNiO layer, a SnO layer, and a ZnO layer, the conductive oxide layer 16 further suppresses the diffusion of Pb from the PZT-based ferroelectric layer 14 to the silicon oxide layer 12, thereby further reducing the Pb content in the silicon oxide layer 12. Furthermore, the conductive oxide layer 16 has sufficiently excellent conductivity, thereby ensuring sufficient electrical conductivity between the electrode layer 13 and the PZT-based ferroelectric layer 14. Furthermore, when the thickness of the conductive oxide layer 16 is within the range of 0.05 μm to 0.20 μm, the diffusion of Pb into the silicon oxide layer 12 is prevented, thereby further reducing the Pb content in the silicon oxide layer 12.

[0039] Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate within the scope of the technical concept of the invention. For example, in the present embodiment, the insulating oxide layer 15 and the conductive oxide layer 16 are described as being formed, but the present invention is not limited thereto and only the insulating oxide layer may be formed, or only the conductive oxide layer may be formed. In other words, in the present invention, either one or both of the insulating oxide layer formed between the silicon oxide layer and the electrode layer and the conductive oxide layer formed between the electrode layer and the PZT-based ferroelectric layer may be formed.

[0040] In the present embodiment, the insulating oxide layer 15 is formed by a sol-gel method in the insulating oxide layer forming step S02. However, the present invention is not limited to this. For example, the insulating oxide layer 15 may be formed by a sol-gel method. ２ , TiO２ , HfO ２ , Al ２ O ３ Alternatively, the insulating oxide layer 15 may be formed by a sputtering method using a sputtering target made of a conductive oxide (RuO, LaNiO, SnO, ZnO). Similarly, in the present embodiment, the conductive oxide layer 16 is formed by a sol-gel method in the conductive oxide layer forming step S04, but the present invention is not limited to this, and the conductive oxide layer 16 may be formed by a sputtering method using a sputtering target made of a conductive oxide (RuO, LaNiO, SnO, ZnO).

[0041] The results of confirmation experiments conducted to confirm the effectiveness of the present invention will be described below.

[0042] A silicon substrate was prepared, and the surface of this silicon substrate was subjected to thermal oxidation treatment to form a silicon oxide layer with the thickness shown in Table 1. Next, an insulating oxide layer, an electrode layer, and a conductive oxide layer were formed by a sol-gel method, as shown in Table 1.

[0043] Next, a PZT sol-gel solution was applied by spin coating, followed by pre-baking at 300°C for 5 minutes and final baking at 700°C for 1 minute. The application and baking of the PZT sol-gel solution were repeated to form a PZT-based ferroelectric layer with the thickness shown in Table 1. In this way, substrates with PZT-based ferroelectric layers were prepared according to the invention and comparative examples shown in Table 1. For the prepared substrates with PZT-based ferroelectric layers, the Pb content in the silicon oxide layer was measured using the procedure described below, and cross sections along the thickness direction were observed.

[0044] (Pb content in silicon oxide layer) The substrate with the PZT-based ferroelectric layer thus prepared was subjected to depth direction analysis by XPS to measure the Pb content in the silicon oxide layer. Specifically, XPS measurement and surface cutting by argon sputtering were repeated, and the Pb content was calculated in atomic % from the ratio with other elements. Here, the sputtering rate was SiO ２The rate was 6.4 nm / min, calculated as a conversion rate, and the content of each element was measured every minute. Measurements were made 32 times (for a total of 32 minutes, approximately 204.8 nm) from measurement points where the Si content was 5% or more or where the Pt content constituting the electrode layer was 10 atomic % or less. When the average Pb content was 1 atomic % or less, it was evaluated as "A," and when the average Pb content was more than 1 atomic %, it was evaluated as "B."

[0045] (Cross-section observation) The cross section of the prepared substrate with a PZT-based ferroelectric layer was observed with a scanning electron microscope. When an altered phase was confirmed at the interface between the silicon oxide layer and the substrate, it was rated as "B", and when no altered phase was confirmed at the interface between the silicon oxide layer and the substrate, it was rated as "A".

[0046]

[0047] In Comparative Examples 1 to 4, the Pb content in the silicon oxide layer exceeded 1 atomic %, and an altered phase was observed at the interface between the silicon oxide layer and the substrate. It is presumed that Pb caused part of the silicon oxide layer to become lead glass. In contrast, in Inventive Examples 1 to 15, the Pb content in the silicon oxide layer was 1 atomic % or less, and no altered phase was observed at the interface between the silicon oxide layer and the substrate.

[0048] As a result of the above confirmation experiments, it was confirmed that the present invention can provide a substrate with a PZT-based ferroelectric layer that can suppress defects in appearance, the occurrence of leakage current, etc., and can be used stably.

[0049] It is possible to provide a substrate with a PZT-based ferroelectric layer that can suppress defects in appearance, the occurrence of leakage current, etc., and can be used stably.

[0050] REFERENCE SIGNS LIST 10 Substrate with PZT-based ferroelectric layer 11 Substrate 12 Silicon oxide layer 13 Electrode layer 14 PZT-based ferroelectric layer 15 Insulating oxide layer 16 Conductive oxide layer

Claims

1. A substrate with a PZT-based ferroelectric layer, comprising: a substrate; a silicon oxide layer formed on at least the surface of said substrate; an electrode layer laminated on said silicon oxide layer; and a PZT-based ferroelectric layer laminated on said electrode layer, wherein the Pb content in said silicon oxide layer is 1 atomic % or less.

2. A substrate with a PZT-based ferroelectric layer according to claim 1, wherein an insulating oxide layer is formed between said silicon oxide layer and said electrode layer.

3. The insulating oxide layer is made of ZrO ２ layer, TiO ２ layer, HfO ２ layer, Al ２ O ３ 3. The substrate with a PZT-based ferroelectric layer according to claim 2, wherein the PZT-based ferroelectric layer is at least one selected from the group consisting of a PZT-based ferroelectric layer, ...

4. A substrate with a PZT-based ferroelectric layer according to claim 2, wherein the thickness of said insulating oxide layer is in the range of 0.10 μm to 0.30 μm.

5. A substrate with a PZT-based ferroelectric layer according to claim 1 or 2, characterized in that a conductive oxide layer is formed between the electrode layer and the PZT-based ferroelectric layer.

6. The substrate with a PZT-based ferroelectric layer according to claim 5, wherein the conductive oxide layer is at least one selected from the group consisting of a RuO layer, a LaNiO layer, a SnO layer, and a ZnO layer.

7. A substrate with a PZT-based ferroelectric layer according to claim 5, wherein the thickness of said conductive oxide layer is in the range of 0.05 μm to 0.20 μm.

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