JP2014146945A - Piezoelectric element wafer forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element wafer forming method that is more productive by reducing man-hour requirements.SOLUTION: The piezoelectric element wafer forming method includes a corrosion-resistant film forming step S1, a resist film forming step S2, an exposure step S3, a predetermined resist film stripping step S4, an exposed corrosion-resistant film stripping step S5 and a piezoelectric wafer etching step S6, where the exposed corrosion-resistant film stripping step S5 and the piezoelectric wafer etching step S6 are repeated until desired steps are formed on the front and rear main surfaces of a piezoelectric wafer 10, and subsequently to the formation of the desired steps, includes an overall resist film stripping step S8, an overall corrosion-resistant film stripping step S9, a resist film forming step S10, an exposure step S11, a predetermined resist film stripping step S12, a piezoelectric wafer contour etching step S13 of etching the piezoelectric wafer through from the front surface to the rear surface, and an overall resist film stripping step S14.

Description

  The present invention relates to a piezoelectric element wafer forming method using an etching technique.

  Conventionally, the outer shape of a small electronic component such as a piezoelectric element used in a piezoelectric device has been formed using a photolithography technique, a wet etching technique, and a dry etching technique. The miniaturized piezoelectric element has a plurality of piezoelectric elements formed on a plate-like piezoelectric wafer cut at a predetermined angle with respect to the crystal axis.

  For example, as shown in FIG. 4, the method for forming a piezoelectric element is a corrosion-resistant film forming step (S1) in which a corrosion-resistant film is deposited on a piezoelectric wafer. Next, a resist film forming step (S2) for forming a resist film on the corrosion resistant film deposited on the piezoelectric wafer. Next, an exposure step (S3) in which a mask having a predetermined external pattern is placed on the resist film and exposed. Next, a predetermined resist film peeling step (S4) for peeling by developing the resist film at the exposed portion. Next, an exposed corrosion-resistant film peeling step (S5) for peeling the corrosion-resistant film from which the resist film at the exposed portion has been peeled off. Next, a piezoelectric wafer etching step (S6) for etching the piezoelectric wafer. Next, an entire resist film peeling step (S7) for peeling off the resist film in the unexposed portion. Next, a total corrosion-resistant film peeling step (S9) for peeling the corrosion-resistant film from which the resist film in the unexposed portion has been peeled off. Next, a resist film forming step (S10) for forming a resist film on the piezoelectric wafer. Next, an exposure step (S11) is performed in which a mask having an external pattern formed so as to leave one side of a portion to be a piezoelectric element is left on the resist film and exposed. Next, a predetermined resist film peeling step (S12) for peeling by developing the resist film in the exposed portion. Next, a piezoelectric wafer outer shape etching step (S13) is performed in which the piezoelectric wafer is etched to leave one side and penetrate from the front surface to the back surface. Next, through the entire resist film peeling step (S14) for peeling off the resist film in the unexposed portion, the outer shape of the piezoelectric element is formed on the piezoelectric wafer to form the piezoelectric element wafer.

JP 2007-294751 A

  However, in the piezoelectric element, the central portion of the main surface of the piezoelectric element is thicker than the end portion of the main surface of the piezoelectric element so that vibration energy is concentrated at the center of the piezoelectric element. It is formed by providing a plurality of steps toward the center of the main surface of the piezoelectric element. In this step formation, after the entire resist film peeling step (S7) in FIG. 4, it is determined whether a desired step is formed on the piezoelectric element (S8). If the desired step is not formed, the resist film is formed. The steps from step (S2) to the entire resist film peeling step (S7) are repeated until a desired step is formed. If a desired level difference is formed, the process proceeds to a total corrosion resistant film peeling step (S9). Thus, a plurality of steps are provided from the end of the main surface of the piezoelectric element toward the center of the main surface of the piezoelectric element. In addition, in order to provide this step, the mask having a predetermined external pattern on the resist film has to be replaced as many times as the desired step is formed. For this reason, the conventional method for forming a piezoelectric element wafer is a factor that requires man-hours and deteriorates productivity. In addition, the conventional method for forming a piezoelectric element wafer requires a plurality of masks to provide a plurality of steps, which may increase the cost and man-hours for managing the mask. Accordingly, an object of the present invention is to provide a method for forming a piezoelectric element wafer that solves the above problems and does not require man-hours and has high productivity.

  According to the present invention, a piezoelectric element wafer forming method includes a corrosion-resistant film forming step of forming a corrosion-resistant film on the front and back main surfaces of a piezoelectric wafer, a resist film forming step of forming a resist film on the corrosion-resistant film, and a resist film An exposure process for exposing the front and back surfaces of the resist film with a predetermined outer pattern, a predetermined resist film peeling process for peeling the front and back resist films exposed or not exposed in the exposure process, and a corrosion-resistant film at the part where the resist film is peeled off An exposed anticorrosive film peeling step that peels off and a piezoelectric wafer etching step that etches portions exposed by peeling off the anticorrosive film, and an exposed anticorrosive film peeling step until a desired step is formed on the main surface of the front and back surfaces of the piezoelectric wafer. And the piezoelectric wafer etching process are repeated to remove all resist films on the piezoelectric wafer and to remove all resist films on the piezoelectric wafer. A film peeling process, a resist film forming process for forming a resist film on the main surfaces of the front and back surfaces of the piezoelectric wafer, an exposure process for exposing the front and back surfaces of the resist film with a predetermined external pattern, and an exposure process that is exposed or not exposed A predetermined resist film peeling step for peeling the resist films on the front and back sides, a piezoelectric wafer outer shape etching step for etching the exposed portion of the resist film by peeling from the front surface to the back surface, and all resist films on the piezoelectric wafer And a resist film peeling step for peeling off the resist film.

  In the method for forming a piezoelectric element wafer according to the present invention, the piezoelectric element provided on the piezoelectric wafer has a main portion of the piezoelectric element from the end of the main surface of the piezoelectric element by repeating the exposed corrosion-resistant film peeling step and the piezoelectric wafer etching step a plurality of times. A plurality of steps can be provided toward the center of the surface. Therefore, the piezoelectric element wafer forming method according to the present invention does not require man-hours, improves productivity, and eliminates the need for a plurality of masks having a predetermined outer shape pattern for providing a plurality of steps. Management man-hours can also be reduced.

It is a flowchart explaining the process of the piezoelectric element wafer formation method in embodiment of this invention. It is a figure which shows the process of the piezoelectric element wafer formation method in embodiment of this invention, (a) is a figure which shows the state in which the corrosion-resistant film was formed, (b) is a figure which shows the state in which the resist film was formed. (C) is a figure which shows the state of exposure, (d) is a figure which shows the state which peeled the predetermined resist film, (e) is a figure which shows the state which peeled the exposure corrosion-resistant film, (f) ) Is a diagram showing a state where the piezoelectric wafer is etched, (g) is a diagram showing a state where the exposed corrosion-resistant film is peeled off, and (h) is a diagram showing a state where the piezoelectric wafer is etched. (I) is a figure which shows the state which peeled the exposure corrosion-resistant film, (j) is a figure which shows the state which etched the piezoelectric wafer, (k) is a figure which shows the state which peeled the resist film Yes, (l) is a view showing a state in which the corrosion-resistant film is peeled off. It is a figure which shows a part of piezoelectric element wafer in embodiment of this invention, (a) is a figure which shows the state in which the resist film was formed, (b) is a figure which shows the state of exposure, (c) Is a diagram showing a state where a predetermined resist film is peeled off, (d) is a diagram showing a state where a piezoelectric wafer is etched and penetrated from the front surface to the back surface, and (e) is a diagram showing a state where all resist films are peeled off. It is a perspective view shown. It is a flowchart explaining the process of the conventional piezoelectric element wafer formation method.

  Hereinafter, some exemplary embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. In addition, the illustration is exaggerated for the sake of clarity. In addition, the main surface in this embodiment is the widest surface and a plane parallel to it in the three-dimensionally formed piezoelectric wafer.

  As shown in FIG. 1, the piezoelectric element wafer forming method according to the embodiment of the present invention includes a corrosion resistant film forming step (S1), a resist film forming step (S2), an exposure step (S3), and a predetermined resist film peeling step. (S4) After the exposed corrosion-resistant film peeling step (S5) and the piezoelectric wafer etching step (S6), it is determined whether a desired number of steps is formed (S7). If the desired number of steps is not formed, exposure is performed. When the desired number of steps is formed by repeating the corrosion-resistant film peeling step (S5) and the piezoelectric wafer etching step (S6), the entire resist film peeling step (S8), the total corrosion-resistant film peeling step (S9), and the resist film formation Through the step (S10), the exposure step (S11), the predetermined resist film peeling step (S12), the piezoelectric wafer outer shape etching step (S13), and the entire resist film peeling step (S14), 1 is formed in plural.

  The piezoelectric wafer 10 is made of, for example, a flat plate crystal cut at a predetermined angle with respect to the crystal axis, and is light-etched to remove a layer roughened by polishing.

[Corrosion-resistant film forming step (S1)]
As shown in FIGS. 1 and 2A, the corrosion resistant film 2 is made of, for example, a metal film of Cr (chromium), and the corrosion resistant film 2 is formed on the front and back main surfaces of the piezoelectric wafer 10. The corrosion resistant film 2 is formed by, for example, vapor deposition using a vapor deposition device or sputtering.

[Resist film forming step (S2)]
As shown in FIGS. 1 and 2B, a resist film 3 is formed on the anticorrosion film 2 formed on the front and back main surfaces of the piezoelectric wafer 10 in the anticorrosion film forming step (S1). This resist film 3 is formed on the corrosion-resistant film 2 by a spin coat method, an electrodeposition resist method, a spray coat method or the like.

[Exposure Step (S3)]
As shown in FIG. 1 and FIG. 2C, the resist film 3 is exposed by sandwiching the piezoelectric wafer 10 on which the corrosion-resistant film 2 and the resist film 3 are formed with a mask 4 on which a predetermined outer shape pattern is formed. Thereby, the surface of the resist film 3 provided on the front and back main surfaces of the piezoelectric wafer 10 is exposed with a predetermined outer shape pattern.

[Predetermined resist film peeling step (S4)]
As shown in FIG. 1 and FIG. 2D, the resist film 3 on the front and back surfaces exposed or not exposed in the exposure step (S3) is peeled off by developing. The developing method includes a positive type method in which the exposed resist film 3 is peeled off and a negative type method in which the resist film 3 not exposed is peeled off.

[Exposed corrosion-resistant film peeling step (S5)]
As shown in FIG. 1 and FIG. 2E, the corrosion-resistant film 2 exposed by peeling off the resist film 3 is peeled off by etching to expose the surface of the piezoelectric wafer 10. As an etching method, there are a dry etching method in which etching is performed using a reactive gas, ions, or the like, and a wet etching method in which etching is performed using a liquid.

[Piezoelectric wafer etching process (S6)]
As shown in FIGS. 1 and 2F, the front and back surfaces of the piezoelectric wafer 10 exposed by peeling off the corrosion-resistant film 2 are removed to a desired depth by etching to form steps.

[Determining if a desired number of steps is formed (S7)]
In the piezoelectric element 1, the central portion of the main surface of the piezoelectric element 1 is formed thicker than the end portion of the main surface of the piezoelectric element 1 in order to concentrate vibration energy at the center of the piezoelectric element 1. This shape is solved by providing a plurality of steps from the end of the main surface of the piezoelectric element 1 toward the center of the main surface of the piezoelectric element 1. Therefore, it is determined whether the desired number of steps is formed. If the desired number of steps is not formed, the exposed corrosion-resistant film peeling step (S5) and the piezoelectric wafer etching step (S6) until the desired number of steps is reached. When the desired number of steps is formed, the process proceeds to the entire resist film peeling step (S8).

  For example, when there are two steps, as shown in FIG. 2G, the corrosion-resistant film 2 is sandwiched between the resist film 3 and the portion to be the piezoelectric element 1, so that the portion where the corrosion-resistant film 2 is exposed. Between the resist film 3 and the portion to be the piezoelectric element 1, that is, the side surface portion of the corrosion-resistant film 2 is peeled off by etching to expose the surface of the portion to be the piezoelectric element 1 (exposed corrosion-resistant film peeling step (S5 )). At this time, the side surface of the corrosion-resistant film 2 is peeled off toward the center side of the portion that becomes the piezoelectric element 1. Next, as shown in FIG. 2 (h), the front and back surfaces of the portion that becomes the piezoelectric element 1 exposed by peeling off the corrosion-resistant film 2 are removed to a desired depth by etching, and the first step is removed. Form (piezoelectric wafer etching step (S6)). Next, as shown in FIG. 2 (i), the corrosion resistant film 2 is sandwiched between the resist film 3 and the portion to be the piezoelectric element 1 as in FIG. 2 (g), so that the corrosion resistant film 2 is exposed. The portion between the resist film 3 and the portion to be the piezoelectric element 1, that is, the side portion of the corrosion-resistant film 2 is peeled off by etching to expose the surface of the piezoelectric wafer 10 (exposed corrosion-resistant film peeling step (S 5 )). Also at this time, as in FIG. 2G, the side surface of the corrosion-resistant film 2 is peeled off toward the center side of the portion that becomes the piezoelectric element 1. Next, as shown in FIG. 2 (j), the front and back surfaces of the portion to be the piezoelectric element 1 exposed by peeling off the corrosion-resistant film 2 are removed to a desired depth by etching, and the second step is removed. Form (piezoelectric wafer etching step (S6)). Thus, a desired level | step difference is formed by repeating the above-mentioned process.

[All resist film peeling step (S8)]
As shown in FIGS. 1 and 2 (k), all the resist film 3 formed on the piezoelectric wafer 10 is peeled off.

[Total corrosion-resistant film peeling step (S9)]
As shown in FIG. 1 and FIG. 2 (l), all the corrosion-resistant film 2 formed on the piezoelectric wafer 10 from which the resist film 3 has been peeled is peeled off.

[Resist film forming step (S10)]
As shown in FIGS. 1 and 3A, a resist film 3 is newly formed on the front and back main surfaces of the piezoelectric wafer 10. The resist film 3 is formed by a spin coating method, an electrodeposition resist method, a spray coating method, or the like.

[Exposure Step (S11)]
As shown in FIG. 1 and FIG. 3B, the resist film 3 is exposed by being sandwiched by a mask 4 having an external pattern formed so as to leave one side of a portion to be the piezoelectric element 1 on the resist film 3. . As a result, the resist film 3 provided on the front and back main surfaces of the piezoelectric wafer 10 is exposed with a predetermined outer shape pattern formed so as to leave one side of the portion to be the piezoelectric element 1.

[Predetermined resist film peeling step (S12)]
As shown in FIGS. 1 and 3 (c), the resist films 3 on the front and back surfaces exposed or not exposed in the exposure step (S11) are developed to be peeled off. The developing method includes a positive type method in which the exposed resist film 3 is peeled off and a negative type method in which the resist film 3 not exposed is peeled off. In addition, the portion where the resist film 3 is peeled is exposed with a predetermined outer shape pattern formed so as to leave one side of the portion to be the piezoelectric element 1, so the other three sides of the portion to be the piezoelectric element 1 are exposed. It becomes.

[Piezoelectric Wafer Outline Etching Step (S13)]
As shown in FIG. 1 and FIG. 3D, the exposed three sides of the front and back surfaces of the piezoelectric wafer 10 are etched to penetrate from the front surface to the back surface of the piezoelectric wafer 10.

[All resist film peeling step (S14)]
As shown in FIGS. 1 and 3 (e), the resist film 3 formed on the piezoelectric wafer 10 is all removed.

  As described above, by configuring the piezoelectric element wafer forming method according to the embodiment of the present invention, the piezoelectric element 1 has the central portion of the main surface of the piezoelectric element 1 with the main part of the piezoelectric element 1 without man-hours compared to the related art. It can be formed thicker than the edge of the surface. Therefore, the method for forming a piezoelectric element wafer according to the present invention improves productivity and eliminates the need for a plurality of masks 4 having a predetermined outer shape pattern for providing a plurality of steps, thereby reducing costs and management man-hours for the masks 4. Can be reduced.

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Corrosion-resistant film 3 Resist film 4 Mask 10 Piezoelectric wafer

Claims (1)

A corrosion-resistant film forming process for forming a corrosion-resistant film on the front and back main surfaces of the piezoelectric wafer;
A resist film forming step of forming a resist film on the corrosion-resistant film;
An exposure step of exposing the front and back of the resist film with a predetermined external pattern;
A predetermined resist film peeling step for peeling off the resist films on the front and back surfaces exposed or not exposed in the exposure step;
An exposed corrosion-resistant film peeling step for peeling off the corrosion-resistant film where the resist film has been peeled off;
A piezoelectric wafer etching step of etching a portion exposed by peeling off the corrosion-resistant film,
The exposed corrosion-resistant film peeling step and the piezoelectric wafer etching step are repeated until desired steps are formed on the main surfaces of the front and back surfaces of the piezoelectric wafer,
A total resist film peeling step for peeling all resist films on the piezoelectric wafer;
A total corrosion-resistant film peeling step for peeling all the corrosion-resistant films on the piezoelectric wafer;
A resist film forming step of forming a resist film on the front and back main surfaces of the piezoelectric wafer;
An exposure step of exposing the front and back of the resist film with a predetermined external pattern;
A predetermined resist film peeling step for peeling off the resist films on the front and back surfaces exposed or not exposed in the exposure step;
Piezoelectric wafer outer shape etching step of etching the portion exposed by peeling off the resist film and penetrating from the front surface to the back surface;
A method for forming a piezoelectric element wafer, comprising: a whole resist film peeling step for peeling off all resist films on the piezoelectric wafer.

Images