JP2000244032A - Conductive film on piezoelectric element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the continuity between the faces of a piezoelectric element by integrally forming a conductive film having a uniform thickness and containing no junction in its structure. SOLUTION: A method for manufacturing a conductive film having a uniform thickness and containing no junction in its structure on a piezoelectric element includes a step of forming a metallic film in a uniform thickness on the whole surface of the piezoelectric element, a step of forming a resist film in a uniform thickness on the metallic film, and a step of arranging a mask on the main surface of the resist film. The method also includes a step of exposing the resist film at an upward angle of 50 deg.-70 deg. from the mask and developing the exposed resist film, a step of etching the exposed part of the metallic film after development, and a step of removing the resist film left on the metallic film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a conductive film formed on a piezoelectric element used for a vibrator, a sensor element, and the like, and a method for manufacturing the conductive film.

[0002]

2. Description of the Related Art In recent years, miniaturization of electronic components has been rapidly progressing. Accordingly, the elements housed in the component package must also be reduced in size. Above all, there is a remarkable reduction in size of a piezoelectric component equipped with a piezoelectric element using quartz or another piezoelectric material. Therefore, the miniaturization and precision of the piezoelectric element to be housed in the component became necessary, so the method of manufacturing the piezoelectric element was to manufacture the outer shape of the piezoelectric element itself and to form an electrode film that was formed so as to extend over multiple surfaces of the piezoelectric element. Alternatively, a photolithography method is used for manufacturing a conductive film such as a wiring formed so as to electrically connect an electrode film formed on each surface of a piezoelectric element.

[0003]

However, when a conductive film to be formed on a piezoelectric element is formed by photolithography, the following problems occur in the formation process. First, a metal such as gold, silver or an alloy is vapor-deposited uniformly on the entire surface of the piezoelectric element, and a resist film is applied thereon. There is a problem that it becomes thinner than that. This state is shown in FIG.

[0004] This is because conventionally, a piezoelectric element having a multi-layered metal film deposited thereon is immersed in a resist solution, and then the excess resist solution is removed to apply the resist film over the entire surface of the multi-layer metal film. This method is very simple, but the resist thickness at the edge of the piezoelectric element is thinner than the other parts due to the surface tension of the resist solution, and the thickness is not uniform throughout the film. In this case, the metal film under the resist film at the edge portion of the piezoelectric element cannot be completely protected by the etching solution, and the metal film is cut at the edge portion, so that conduction between the respective surfaces of the piezoelectric element cannot be obtained or there is no conduction. Even so, the conductive state becomes very unstable.

Conventionally, in order to avoid insulation or an unstable state at the edge portion, after forming a conductive film by photolithography, the conductive portion formed on each surface is placed at the edge portion where conduction is required between the piezoelectric element surfaces. There is a need for a process of forming a metal film having such a shape as to connect the films by a vapor deposition method to ensure conduction. In addition, when the metal film having such a shape is formed, it is considered that the vibration state of the piezoelectric element is affected to a considerable extent. This state is shown in FIG.

Next, after applying a resist film, a mask is arranged on the main surface, and the main surface and the side surface are exposed from above the mask. Unless exposure is not good and high-precision exposure is not performed, there is a possibility that the resist film on the side surface remaining after development may have a difference from the desired shape, and the shape of the conductive film after etching may be irregular. There is also.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. First, in a conductive film formed over a plurality of surfaces of a piezoelectric element by a photolithography method, another conductive film is formed on one side of the piezoelectric element. A conductive film formed on the piezoelectric element, wherein the conductive film formed so as to reach the surface has a uniform thickness at all locations, and has no joint in the structure of the conductive film and is integrally formed. is there.

[0008] Further, the manufacturing method includes a step of forming a multilayer metal film as a material of a conductive film to a uniform thickness on the entire surface of the piezoelectric element processed into a desired outer shape, and a step of forming a resist film on the multilayer metal film. A step of forming a film having a uniform thickness, a step of arranging a mask on which a desired conductive film pattern to be formed on the main surface and side surfaces is formed on the main surface of the resist film, At the angle of °, the step of simultaneously exposing and developing the resist film on the main surface and the side surface, the step of removing the exposed part of the metal film by removing the resist film after the development, and the step of etching the remaining multi-layered metal film And removing the resist film.

According to the present invention, a metal film having such a shape as to connect a conductive film formed on each surface is formed by vapor deposition on an edge portion where conduction is required between each surface of the piezoelectric element. Is eliminated, and since there is no joint portion in the structure of the conductive film and it is integrally formed, there is no factor that hinders the vibration of the piezoelectric element, and the structure is stabilized.

Further, by exposing the mask at an angle of 50 ° to 70 ° above, the resist masks formed on the main surface and the side surfaces can be simultaneously and accurately formed into a desired shape. A desired conductive film shape can be obtained at the time of etching.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same reference numeral indicates the same object.

FIG. 1 shows an edge portion of a piezoelectric element 1 after forming a conductive film 2 in the present invention. Actually, a plurality of piezoelectric elements are formed on a single piezoelectric element by photolithography, and a conductive film or the like is simultaneously formed on the plurality of piezoelectric elements. A portion including the edge portion is enlarged and shown in a simplified form of the film shape and the like. Note that the conductive film in the present invention is an electrode film formed so as to extend over a single surface or a plurality of surfaces of a piezoelectric element, or an electrode film formed on each surface of a piezoelectric element so as to be electrically connected. This refers to the created wiring and the like. Further, in the present invention, a piezoelectric element whose outer shape is formed by a photolithography method is used, but the present invention is also applicable to a conductive film formed on a piezoelectric element whose outer shape is formed by another method.

In the conductive film 2 of the present invention, the piezoelectric element 1
The structure of the conductive film 2 from one surface to the other surface is an integrated structure having a uniform film thickness and no structural connection anywhere. With such a structure, the risk of non-conduction of the conductive film 2 at the edge portion is eliminated, and since there is no extra mass on the surface of the piezoelectric element 1, stress applied to the vibration characteristics of the piezoelectric element 1 is minimized. Can be.

FIG. 2 shows a method of manufacturing the conductive film 2 according to the present invention. FIG. 2 shows a cross section of a part of the piezoelectric element and simplifies the shape of the film and the like so that the process of forming the conductive film 2 is clear.

First, gold is applied to the entire surface of the cleaned piezoelectric element 1.
Silver or an alloy is deposited in a multilayer structure to a uniform thickness on all surfaces to form a multilayer metal film 2a.

Next, a resist is formed with a uniform thickness on the entire surface of the multilayer metal film 2a to obtain a resist film 3. In the present invention, as a method for forming a uniform thickness of the resist,
A method of forming the resist film 3 using an electrodeposition method or a method of forming a resist film 3 by applying a resist using a spray is used. By this method, the resist film 3 can be formed uniformly on all surfaces of the multilayer metal film.

Next, among the respective surfaces of the piezoelectric element 1 on which the multilayer metal film 2a and the resist film 3 are formed,
A glass mask 4 on which a pattern of a conductive film 2 to be formed on the main surface and a side surface continuous with the main surface is arranged.

Next, 5 mm from above the placed glass mask 4.
The resist film 3 formed on the main surface and the side surface is exposed at an angle of 0 ° to 70 °. Exposure angle is 50 ° -70 compared to conventional
°, the mask pattern on the main surface and the side surface can be exposed to the resist film 3 more accurately than in the past. In this embodiment, exposure is performed by irradiating an electromagnetic wave having a wavelength in the ultraviolet region. However, an electromagnetic wave in another wavelength region such as visible light may be used as long as the resist film can be exposed. After this exposure, development is performed.

Next, the piezoelectric element 1 having the resist film 3 (resist mask for the metal film) remaining on the multilayer metal film 2a in a desired pattern of the conductive film 2 is etched to expose the multilayer metal film without the resist film 3. The film part is removed.

Next, the resist film 3 on the multilayer metal film 2a remaining on the surface of the piezoelectric element 1 is removed, and a desired conductive film 2 is formed on the piezoelectric element 1.

[0021]

According to the present invention, a metal film having such a shape as to connect a conductive film formed on each surface is formed by an evaporation method at an edge portion where conduction is required between each surface of the piezoelectric element, thereby ensuring conduction. This eliminates the need for a step to perform, thus reducing man-hours. In addition, since there is no bonding portion in the structure of the conductive film and it is formed integrally, there is no factor that deteriorates the characteristics of the piezoelectric element, and the characteristics can be stabilized. Further, the exposure angle is set to 5
By setting the angle to 0 ° to 70 °, the shapes of the resist masks formed on the main surface and the side surfaces can be formed simultaneously and accurately to a desired shape, and a desired conductive film can be formed at a later etching time. The shape can be reliably obtained.

[Brief description of the drawings]

FIG. 1 shows a film shape of the present invention.

FIG. 2 shows a process chart for forming a conductive film of the present invention.

FIG. 3 shows a conventional resist film shape when a resist film is applied.

FIG. 4 shows a conventional film shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Conductive film 2a Multilayer metal film 3 Resist film 4 Mask

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03H 9/13 H01L 41/22 Z

Claims (2)

[Claims] 1. A conductive film formed over a plurality of surfaces of a piezoelectric element by a photolithography method, wherein the conductive film formed from one surface of the piezoelectric element to the other surface includes all the conductive films. A conductive film on a piezoelectric element, wherein the conductive film has a uniform thickness at a portion and has no joint portion in the structure of the conductive film and is integrally formed. 2. The entire surface of a piezoelectric element processed into a desired outer shape,
A step of forming a multilayer metal film as a material of the conductive film with a uniform film thickness; a step of forming a resist film with a uniform film thickness on the multilayer metal film; Arranging a mask on which a desired conductive film pattern to be formed on a plurality of side surfaces is formed;
Simultaneously exposing and developing the resist film on the main surface and the side surface of the piezoelectric element at an angle of 0 °, and removing the resist film by removing the exposed portion of the multilayer metal film by etching; A method for producing a conductive film on a piezoelectric element, comprising: a step of removing the resist film on the remaining multilayer metal film.