JPH07154187A - Structure of electrode of piezoelectric vibrator and forming method for the electrode - Google Patents

Abstract

PURPOSE:To provide the piezoelectric vibrator, small in variation with time by forming an electrode film of the piezoelectric vibrator with a metallic layer and a protective layer formed by an oxidation layer formed on the surface layer of the metallic layer. CONSTITUTION:The electrode film of the piezoelectric vibrator is made up of a metallic layer 11 comprising a metallic single layer using an active metal with a small electric resistance such as aluminum, titanium or copper on a piezoelectric material 10 and up of a protective layer 12 comprising an oxidation layer, a nitride layer or a carbide layer chemically stable. When an oxidation layer is adopted for the protective layer 12, after the metallic layer 11 forming the electrode film of the piezoelectric vibrator is formed on the piezoelectric material 10, the piezoelectric material 10 is supported and fixed to a support member with a conductive adhesives or the like. Then heat treatment or plasma processing is applied to the piezoelectric material 10 to change a surface layer of the metallic layer 11 into an oxide by a chemical reaction. Thus, the electrode film for the piezoelectric vibrator is formed by forming the protective layer 12 made of the oxidation layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure of a piezoelectric vibrator and an electrode forming method, and more particularly to an electrode structure and an electrode forming method for highly stabilizing the piezoelectric vibrator.

[0002]

2. Description of the Related Art Conventionally, as an electrode structure of a piezoelectric vibrator,
On the piezoelectric body 40 as shown in FIG.
And the second layer 41b, the first layer 41 made of nickel, chromium, or the like having a role of an adhesion layer for enhancing the adhesion.
a and a role of an excitation layer for vibrating the piezoelectric body,
Second made of metal with low electric resistance such as gold or silver
There is an electrode film composed of a plurality of layers including the layer 41b.

A piezoelectric body 30 as shown in FIG.
An electrode film composed of a metal single-layer metal layer 31 having both the functions of the first layer 41a and the second layer 41b shown in FIG. 4 and having a low electric resistance is also used.

One of the characteristics of the piezoelectric vibrator is a change over time that indicates a deviation in the oscillation frequency of the piezoelectric vibrator before and after a certain period of time. This change over time may be affected by the change in mass on the piezoelectric body. Are known. As the characteristics of the piezoelectric vibrator, the smaller this temporal change, the better.

[0005]

As shown in FIG. 4A, the electrode film formed on the piezoelectric body 40 is the first layer 41a.
And in the case of a multi-layer electrode film including the second layer 41b,
When the second layer 41b is silver, it gradually reacts with oxygen and the like existing in the surrounding atmosphere, so that the mass change on the piezoelectric body 40 gradually occurs, which adversely affects the change over time.

Even when the second layer 41b is made of gold having a relatively low activity, it is heated to solidify the conductive adhesive for fixing the piezoelectric body to the supporting member when manufacturing the piezoelectric vibrator. Alternatively, the surface of the piezoelectric body is heated for degassing for the purpose of stabilizing the characteristics.
As shown in (b), the active metal composing the first layer 41a diffuses in the second layer 41b and reaches the surface to form the diffusion layer 43.

The active metal thus exposed on the surface naturally causes oxidation in the diffusion layer 43 which gradually reacts with oxygen and the like existing in the surrounding atmosphere, and FIG.
Although the natural oxide layer 42 is formed as shown in (c), the reaction with the surrounding atmosphere in the diffusion layer 43 gradually progresses until the surface has no active component. For this reason, the mass increase due to the reaction gradually occurs, which adversely affects the change over time.

On the other hand, as shown in FIG.
0 is an active metal single-layer metal layer 31.
Also in this case, since the metal layer 31 itself is active, the surface thereof gradually reacts with oxygen or the like existing in the surrounding atmosphere to be gradually oxidized, and the natural oxide layer 32 as shown in FIG. However, the reaction with the surrounding atmosphere on the surface of the metal layer 31 gradually progresses until the surface has no active component. As a result, mass increase due to the reaction gradually occurs, which adversely affects the change with time.

Therefore, an object of the present invention is to provide a piezoelectric vibrator having a small change with time due to mass increase due to reaction with oxygen or the like in the surrounding atmosphere on the surface of the electrode film formed on the piezoelectric body of the piezoelectric vibrator. An object is to provide an electrode structure and a manufacturing method thereof.

[0010]

In order to achieve the above object, in the present invention, the electrode film of the piezoelectric vibrator adopts the following constitution and its manufacturing method.

The electrode film of the piezoelectric vibrator of the present invention is a metal layer,
And a protective layer formed of an oxide layer formed on the surface of the metal layer. Further, the method of manufacturing an electrode film of a piezoelectric vibrator of the present invention is a method in which a single layer or a plurality of metal layers forming the electrode film are formed by a vacuum deposition method or a sputtering method on a supporting member, a conductive adhesive, etc. After being fixed in place, the protective layer made of an oxide layer is formed on the surface layer of the metal layer by heat treatment or plasma treatment in the air or an oxidizing atmosphere.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a sectional view showing an electrode structure of a piezoelectric vibrator according to the present invention, and FIG. 1B is a partially enlarged sectional view of the electrode structure of a piezoelectric vibrator according to the present invention.

The electrode film of the piezoelectric vibrator of the present invention is shown in FIG.
As shown in (a), a metal layer 11 composed of a single metal layer of aluminum, titanium, or copper, which is active and has a small electric resistance value, and a natural oxidation on the surface of the metal layer 11 are formed on the piezoelectric body 10 over time. The protective layer 12 is composed of a chemically stable oxide layer, a nitride layer, or a carbonized layer for suppressing a reaction accompanied by an increase in mass.

First, the case where an oxide layer made of an oxide is used as the protective layer 12 in order to obtain the electrode film of the piezoelectric vibrator of the present invention will be described.

In order to form the piezoelectric vibrator, the piezoelectric member 10 having the electrode film formed thereon is used as a support member for electrically connecting the electrode film of the piezoelectric vibrator to the outside as shown in FIG. 5A. 5
6 needs to be supported and fixed with a conductive adhesive or the like. First, a method of forming the electrode film 54 of the piezoelectric vibrator when the piezoelectric body 10 and the supporting member 56 are supported and fixed before forming the protective layer 12 will be described.

After the metal layer 11 forming the electrode film 54 of the piezoelectric vibrator is formed on the piezoelectric body 10 by a film forming method such as a vacuum deposition method or a sputtering method, the piezoelectric body 10 is formed.
Is supported and fixed to a supporting member 56 as shown in FIG. 5A with a conductive adhesive 55 or the like. After that, this support member 5
The piezoelectric body 10 supported and fixed to 6 is heat-treated or plasma-treated in the air or in an oxidizing atmosphere to obtain the piezoelectric body 1.
By changing the surface layer of the metal layer 11 formed on the oxide layer 0 into an oxide by a chemical reaction, the protective layer 12 of the oxide layer is formed to form the electrode film 54 of the piezoelectric vibrator.

When heat treatment or plasma treatment is performed in the air or in an oxidizing atmosphere to change the surface layer of the metal layer 11 formed on the piezoelectric body 10 into an oxide by a chemical reaction, the chemical reaction is from the surface of the metal layer 11. As shown in FIG. 1 (b), the degree of oxidation becomes stronger toward the surface.

Next, after forming the protective layer 12, the piezoelectric body 10 is supported by a supporting member 56 as shown in FIG.
A method of forming the electrode film of the piezoelectric vibrator when fixed will be described.

Also in this case, first, the metal layer 11 forming the electrode film of the piezoelectric vibrator is formed on the piezoelectric body 10 by a film forming method such as a vacuum deposition method or a sputtering method, and then the metal layer 11 is formed. Piezoelectric body 10
By heat treatment or plasma treatment in the air or in an oxidizing atmosphere to change the surface layer of the metal layer 11 formed on the piezoelectric body 10 into an oxide by a chemical reaction, or by a vacuum deposition method, a sputtering method,
Alternatively, the protective layer 12 of the oxide layer is formed by forming an oxide film by a film forming method such as a chemical vapor deposition (CVD) method.

After forming the protective layer 12, the piezoelectric member 10 is attached to the supporting member 56 as shown in FIG.
The oxide is generally an insulator, but it is difficult to conduct it to the outside.

Therefore, before supporting and fixing the piezoelectric body 10 to the supporting member 56 with the conductive adhesive 55 or the like, as shown in FIG. 5B, the piezoelectric body 10 is supported and fixed by the electrode film 54. The protective film 12 is removed only on the portion to be performed, and the metal layer 11 is exposed on the surface so that conduction can be established.

The metal layer 11 and the support member 56 can be electrically connected to each other by preventing the protective layer 12 from being formed on a portion for supporting and fixing the piezoelectric body 10 with a mask when the protective layer 12 is formed. Is possible.

As described above, the protective layer 12 made of a chemically stable oxide is formed on the surface of the metal layer 11 made of an active metal.
By providing, the surface has no active ingredient.
Therefore, a reaction such as a natural oxidation in which the reaction gradually progresses does not occur. Therefore, the change in mass on the piezoelectric body 10 is also eliminated, so that it is possible to suppress the change over time.

Up to this point, the case where the metal layer is a metal single layer which is active and has a small electric resistance value has been described, but the metal layer in the present invention is the first metal layer made of an active metal as shown in FIG.
2a and a second layer 21b made of a metal having a small electric resistance value and formed on the first layer 21a.

In this case, as described in the conventional example, even if the second layer 21b is chemically stable gold, by heat treatment such as solidification of the conductive adhesive or degassing of the piezoelectric surface, The active metal of the first layer 21a is the second layer 21b.
Therefore, by forming the protective layer 22 as shown in FIG. 2, the same effect as in the case of a single metal layer can be obtained.

Although the case where an oxide layer made of an oxide is used as the protective layer has been shown so far, a similar effect can be obtained even if a nitride layer made of a nitride or a carbonized layer made of a carbide is used as the protective layer. You can

When the protective layer is formed by changing the surface of the metal layer by a chemical reaction, heat treatment or plasma treatment is performed in a nitriding atmosphere to obtain a nitrided layer, and in a carbonizing atmosphere to obtain a carbonized layer. Heat treatment or plasma treatment may be performed.

On the other hand, when the protective layer is formed by film formation, a nitride film may be formed to obtain a nitride layer, and a carbide film may be formed on the metal layer to obtain a carbonized layer.

[0029]

As described above, according to the present invention, the electrode film of the piezoelectric vibrator is composed of the metal layer and the protective layer formed on the surface layer of the metal layer, which is composed of the oxide layer, the nitride layer or the carbonized layer. By doing so, a piezoelectric vibrator is produced which has a small change over time due to mass increase due to reaction with oxygen or the like in the atmosphere inside the container of the piezoelectric vibrator on the surface of the electrode film formed on the piezoelectric body of the piezoelectric vibrator. It becomes possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electrode structure of a piezoelectric vibrator according to an example of the invention.

FIG. 2 is a sectional view showing an electrode structure of a piezoelectric vibrator according to another embodiment of the present invention.

FIG. 3 is a sectional view showing an electrode structure of a piezoelectric vibrator in a conventional example.

FIG. 4 is a sectional view showing an electrode structure of a piezoelectric vibrator in another conventional example.

FIG. 5 is a plan view showing a piezoelectric vibrator for explaining an electrode forming method of the piezoelectric vibrator in the example of the present invention.

[Explanation of symbols]

 10 Piezoelectric body 11 Metal layer 12 Protective layer

Claims (14)

[Claims] 1. An electrode structure of a piezoelectric vibrator, wherein an electrode film of the piezoelectric vibrator is composed of a metal layer and a protective layer formed of an oxide layer formed on a surface layer of the metal layer. 2. The electrode structure of a piezoelectric vibrator, wherein the electrode film of the piezoelectric vibrator is composed of a metal layer and a protective layer formed of a nitride layer formed on the surface of the metal layer. 3. The electrode structure of a piezoelectric vibrator, wherein the electrode film of the piezoelectric vibrator is composed of a metal layer and a protective layer formed of a carbonized layer formed on the surface of the metal layer. 4. The electrode structure for a piezoelectric vibrator according to claim 1, wherein the metal layer is a single layer made of a metal that is active and has a low electric resistance value. 5. The metal layer is a plurality of layers including a first layer made of an active metal and a second layer made of a metal having a small electric resistance value formed on the first layer. The electrode structure of the piezoelectric vibrator according to claim 1, 2 or 3. 6. A piezoelectric body having a single layer or a plurality of metal layers forming an electrode film formed on the piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method, and fixed to a supporting member with a conductive adhesive or the like. After that, a method for forming an electrode of a piezoelectric vibrator, characterized in that a protective layer made of an oxide layer is formed on a surface layer of a metal layer by heat treatment or plasma treatment in the air or an oxidizing atmosphere. 7. A piezoelectric body having a single layer or a plurality of metal layers forming an electrode film formed on the piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method and fixed to a supporting member with a conductive adhesive or the like. After that, a method for forming an electrode of a piezoelectric vibrator, characterized in that a protective layer made of a nitride layer is formed on a surface layer of a metal layer by heat treatment or plasma treatment in a nitriding atmosphere. 8. A piezoelectric body in which a single layer or a plurality of metal layers forming an electrode film is formed on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method, and the piezoelectric body is fixed to a supporting member with a conductive adhesive or the like. After that, a method for forming an electrode of a piezoelectric vibrator, characterized in that a protective layer made of a carbonized layer is formed on a surface layer of a metal layer by heat treatment or plasma treatment in a carbonized atmosphere. 9. A single-layer or multiple-layer metal layer forming an electrode film is formed on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method, and is heat-treated or plasma-treated in the air or an oxidizing atmosphere. After forming a protective layer consisting of an oxide layer on the surface of the metal layer by forming a protective layer made of an oxide layer by a vacuum vapor deposition method, a sputtering method, or a film forming method such as a chemical vapor deposition method on the piezoelectric body. A method of forming an electrode of a piezoelectric vibrator, comprising removing a protective layer on a metal layer formed in a portion of the electrode film formed in step 1 for conducting connection and fixing to a supporting member. 10. A single-layer or multiple-layer metal layer forming an electrode film is formed on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method, and heat-treated or plasma-treated in a nitriding atmosphere, Alternatively, a nitride film is formed by a film forming method such as a vacuum vapor deposition method, a sputtering method, or a chemical vapor deposition method to form a protective layer made of a nitride layer on the surface of the metal layer and then formed on the piezoelectric body. A method of forming an electrode of a piezoelectric vibrator, comprising removing a protective layer on a metal layer formed on a portion of the electrode film required for conducting connection and fixing with a supporting member. 11. A single-layer or multiple-layer metal layer forming an electrode film is formed on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method, and heat-treated or plasma-treated in a carbonized atmosphere, Alternatively, by forming a carbonized film by a film forming method such as a vacuum vapor deposition method, a sputtering method, or a chemical vapor deposition method, a protective layer made of a carbonized layer is formed on the surface layer of the metal layer and then formed on the piezoelectric body. A method of forming an electrode of a piezoelectric vibrator, comprising removing a protective layer on a metal layer formed on a portion of the electrode film required for conducting connection and fixing with a supporting member. 12. A support member for a metal layer formed on a piezoelectric body by forming a single layer or a plurality of metal layers forming an electrode film on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method. After applying a mask to the parts required for conductive connection and fixing with, heat treatment or plasma treatment in the air or an oxidizing atmosphere, or a film formed by a vacuum vapor deposition method, a sputtering method, a chemical vapor deposition method, or the like. A method for forming an electrode of a piezoelectric vibrator, comprising forming an oxide film by a forming method to form a protective layer made of an oxide layer on a surface layer of a metal layer. 13. A support member for a metal layer formed on a piezoelectric body by forming a single layer or a plurality of metal layers forming an electrode film on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method. After applying a mask to the parts necessary for conductive connection and fixing with, heat treatment or plasma treatment in a nitriding atmosphere, or by a film forming method such as a vacuum deposition method, a sputtering method, or a chemical vapor deposition method. A method for forming an electrode of a piezoelectric vibrator, comprising forming a protective layer made of a nitride layer on a surface layer of a metal layer by forming a nitride film. 14. A support member for a metal layer formed on a piezoelectric body by forming a single layer or a plurality of metal layers forming an electrode film on a piezoelectric body by a film forming method such as a vacuum deposition method or a sputtering method. After masking the parts required for conductive connection with and fixing with, carbonization is performed by heat treatment or plasma treatment in a carbonization atmosphere, or by a film forming method such as a vacuum deposition method, a sputtering method or a chemical vapor deposition method. A method for forming an electrode of a piezoelectric vibrator, comprising forming a protective layer made of a carbonized layer on a surface layer of a metal layer by forming a film.