WO2018092872A1

WO2018092872A1 - Piezoelectric vibration element manufacturing method

Info

Publication number: WO2018092872A1
Application number: PCT/JP2017/041434
Authority: WO
Inventors: 尚士大島
Original assignee: 株式会社村田製作所
Priority date: 2016-11-21
Filing date: 2017-11-17
Publication date: 2018-05-24

Abstract

A piezoelectric vibration element manufacturing method comprises: a step of forming, from a piezoelectric substrate, an assembly substrate (100) which is provided with a plurality of crosspiece portions (120) extending in a first direction, and which is arranged in a second direction, a plurality of piezoelectric pieces (111) which are positioned between adjacent first crosspiece portion and second crosspiece portion, and which are arranged in the first direction, a plurality of support portions (131) which support the plurality of piezoelectric pieces (111) on the first crosspiece portion, and a protruding portion (142) which protrudes from the second crosspiece portion toward the first crosspiece portion, and which has a distal end spaced apart from the piezoelectric pieces (111); a step of forming a metal layer (300); a step of forming a photoresist layer (500) on the metal layer (300); a step of forming an electrode pattern (510) by exposing and developing the photoresist layer (500); and a step of forming an excitation electrode (314) on a main surface of the piezoelectric pieces (111) by removing the metal layer (300) in accordance with the electrode pattern (510).

Description

Method for manufacturing piezoelectric vibration element

The present invention relates to a method for manufacturing a piezoelectric vibration element.

Piezoelectric vibrators are widely used as signal sources for reference signals used in oscillators and bandpass filters. The piezoelectric vibrator is manufactured, for example, by forming a plurality of piezoelectric pieces on an aggregate substrate (wafer) by etching or the like, and providing excitation electrodes collectively on the plurality of piezoelectric pieces. The excitation electrode is formed by providing a metal layer and a photoresist in this order on the collective substrate, patterning the photoresist, and etching the metal layer.

JP 2005-223396 A

As described above, when the excitation electrodes are collectively provided on the plurality of piezoelectric pieces, a gap is formed around each piezoelectric piece. Photoresist is formed by application in a state of being dissolved in a solvent. However, if unevenness or gaps exist in the aggregate substrate, the spread of the photoresist solution may be inhibited, and the thickness of the photoresist may become uneven. There is. In such a case, in the step of forming the excitation electrode, the photoresist removal by photolithography becomes insufficient, and an unnecessary metal layer may remain.

This invention is made in view of such a situation, and it aims at providing the manufacturing method of the piezoelectric vibration element which can suppress the fluctuation | variation of a frequency characteristic.

A method of manufacturing a piezoelectric vibration element according to one aspect of the present invention includes a step of preparing a piezoelectric substrate, a plurality of bars extending in a first direction and arranged in a second direction intersecting the first direction, and a plurality of bars. A plurality of piezoelectric pieces that are located between the first and second crosspieces adjacent to each other in the section and are arranged in the first direction; a plurality of support sections that support the plurality of piezoelectric pieces on the first crosspiece; Forming a collective substrate from the piezoelectric substrate and projecting from the two crosspieces toward the first crosspiece and having a tip separated from the piezoelectric piece, and a metal on at least the main surface of the piezoelectric piece of the collective substrate A step of forming a layer; a step of applying a solution containing a photoresist on the metal layer to form a photoresist layer; a step of exposing and developing the photoresist layer to form an electrode pattern; and Remove according to pattern and form excitation electrode on main surface of piezoelectric piece Including that a step.

According to the present invention, it is possible to provide a method for manufacturing a piezoelectric vibration element that can suppress fluctuations in frequency characteristics.

FIG. 1 is a flowchart showing a crystal piece forming step in a method for manufacturing a piezoelectric vibration element according to an embodiment of the present invention. FIG. 2 is a flowchart showing an excitation electrode forming step in the method for manufacturing a piezoelectric vibration element according to the embodiment of the present invention. FIG. 3 is a plan view showing the collective substrate after completion of the crystal piece forming step shown in FIG. FIG. 4 is a diagram showing a photoresist coating process by spin coating. FIG. 5 is a diagram schematically showing how the photoresist spreads in FIG. FIG. 6 is a diagram illustrating an aggregate substrate on which an electrode pattern is formed. FIG. 7 is an exploded perspective view of a configuration example of a crystal resonator. FIG. 8 is a cross-sectional view taken along line VIII-VIII of the crystal resonator shown in FIG. FIG. 9 is a perspective view of a crystal resonator element according to a modification.

Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar components are denoted by the same or similar reference numerals. The drawings are exemplary, the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be limited to the embodiment.

<Embodiment>
A method for manufacturing a piezoelectric vibration element according to an embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a flowchart showing a crystal piece forming step in the method of manufacturing a piezoelectric vibration element according to the embodiment of the present invention. FIG. 2 is a flowchart showing an excitation electrode forming step in the method for manufacturing a piezoelectric vibration element according to the embodiment of the present invention. FIG. 3 is a plan view showing the collective substrate after completion of the crystal piece forming step shown in FIG. FIG. 4 is a diagram showing a photoresist coating process by spin coating. FIG. 5 is a diagram schematically showing how the photoresist spreads in FIG. FIG. 6 is a diagram illustrating an aggregate substrate on which an electrode pattern is formed.

First, the crystal piece forming process will be described with reference to FIG. In the following description of the embodiments, for example, a piezoelectric vibrating element is a quartz vibrating element (Quartz Crystal Resonator), a piezoelectric piece is a quartz piece (Quartz Crystal Element), and a piezoelectric substrate is a quartz wafer (Quartz). A crystal substrate such as Crystal Wafer. However, the embodiment according to the present invention is not limited to these.

First, at the start of the crystal piece forming step, a quartz substrate 99 (piezoelectric substrate) made of an artificial quartz plate as a piezoelectric material is prepared. At this time, the quartz crystal substrate 99, which is an artificial quartz, is a plane parallel to the plane specified by the X axis and the Z ′ axis (hereinafter referred to as “XZ ′ plane”. The same applies to the plane specified by other axes. And the Y ′ axis is parallel to the normal direction of the main surface. The Y ′ axis and the Z ′ axis are respectively the X axis, the Y axis, and the Z axis, which are the crystal axes of the artificial quartz crystal, the Y axis and the Z axis around the X axis in the direction from the Y axis to the Z axis. It is an axis rotated at 35 degrees 15 minutes ± 1 minute 30 seconds.

Next, metal layers are formed on both main surfaces of the quartz substrate 99 (S11). The metal layer functions as a corrosion-resistant film against an etching solution (for example, ammonium fluoride or buffered hydrofluoric acid) used when etching the crystal. As such a corrosion-resistant film, for example, a multilayer film composed of a chromium (Cr) layer and a gold (Au) layer is used. The metal layer is formed by vapor deposition or sputtering. Inside the metal layer, the Cr layer is located closer to the quartz substrate 99 than the Au layer, that is, the side in contact with the quartz substrate 99. In addition, the Au layer is located on the opposite side of the Cr layer from the quartz substrate 99 as compared to the Cr layer. The Cr layer increases the adhesion with the quartz substrate 99, and the Au layer increases the corrosion resistance.

Next, a photoresist layer is formed on the metal layer (S12). The photoresist layer is formed by applying a photoresist solution on the metal layer and volatilizing the solvent by heating. The photoresist solution is applied by, for example, a spray method or a spin coat method.

Next, the photoresist layer is exposed and developed to form an external pattern of the crystal piece 110 (piezoelectric piece) (S13). For the photoresist layer, from the viewpoint of adaptability to microfabrication, it is desirable to use a positive photosensitive resin that removes the exposed portion by dissolution. When a positive photosensitive resin is used, the photoresist layer is exposed in a state where a region corresponding to the crystal piece 110 is shielded from light by a photomask, and then an unnecessary portion is washed away by a developer. That is, the shape of the photomask is transferred to the photoresist layer. As a result, the photoresist layer remaining on the metal layer forms an external pattern of the crystal piece 110.

Next, the quartz substrate 99 is removed according to the external pattern (S14). At this time, a plurality of crystal pieces 110 are formed in the crystal substrate 99 by etching using the external pattern of the photoresist layer formed in the previous step. The crystal pieces 110 are not separated into individual pieces and are connected to each other by the crosspieces 120. A specific shape will be described later. In this step, the metal layer is removed by etching in accordance with the external pattern of the photoresist layer, and then the quartz substrate 99 is removed by etching. The etching process is not particularly limited, and is, for example, general wet etching. An iodine-based etching solution is used for the metal layer, and a hydrofluoric acid-based etching solution is used for the crystal.

Next, the photoresist layer and the metal layer are removed (S15). Here, all of the photoresist layer and the metal layer adhering to the quartz substrate 99 are removed. Thereafter, the crystal piece 110 is processed into a mesa structure (S16). The mesa structure can be processed by repeating the same processes as in steps S11 to S15. The difference between steps S11 to S14 in step S16 is that the shape of the photoresist layer in the step corresponding to step S13 is a mesa structure pattern that covers the vibrating portion 117 and exposes the

peripheral portions

118 and 119. The etching of the quartz crystal substrate 99 in the process corresponding to the process S14 is half etching.

The shape of the collective substrate 100 formed through the above steps will be described with reference to FIG. In addition, although the 1st direction D1 and the 2nd direction D2 which are shown in FIG. 3 are directions orthogonal to each other, they may be directions intersecting at an angle other than orthogonal to each other. In the example illustrated in FIG. 3, the first direction D1 is a direction parallel to the Z′-axis direction, and the second direction D2 is a direction parallel to the X-axis direction.

The collective substrate 100 includes a crystal piece 110, a plurality of crosspieces 120, a plurality of support portions 130, and a plurality of protrusions 140. In the example illustrated in FIG. 3, each of the crystal pieces 110 has a rectangular shape having a short side parallel to the first direction D1 and a long side parallel to the second direction D2. In addition, each of the crystal pieces 110 is held by the crosspiece 120 via the support portion 130 on the short side thereof. A space (space) is formed around the crystal piece 110 by removing the crystal substrate 99 by etching except for the connection portion with the support portion 130. As a more specific configuration example, a plurality of first crystal pieces 111 and a plurality of second crystal pieces 112 as an example of the crystal piece 110, a first crosspiece 121 and a second crosspiece 122 as an example of the crosspiece 120, Examples of the support part 130 include a plurality of first support parts 131 and a plurality of second support parts 132, and examples of the protrusion part 140 include a plurality of first protrusion parts 141 and a plurality of second protrusion parts 142, respectively. explain.

The first crystal piece 111 and the second crystal piece 112 are arranged in the first direction D1 at intervals, and are arranged in the second direction D2. The first crosspiece 121 and the second crosspiece 122 each extend in the first direction D1 and are adjacent to each other in the second direction D2. The first crystal piece 111 is provided with a space between the first crosspiece 121 and the second crosspiece 122, and the second crosspiece 122 is provided between the first crystal piece 111 and the second crystal piece 112. Are provided at intervals. That is, the crystal pieces 110 and the crosspieces 120 are alternately arranged in the second direction D2 and are separated from each other. The first crosspiece 121 has an end side 121b on the side close to the first crystal piece 111, and an end side 121a on the side opposite to the end side 121b. The second crosspiece 122 has an end side 122b on the side close to the second crystal piece 112, and an end side 122a on the side close to the first crystal piece 111 (the side opposite to the end side 122b). The first crystal piece 111 and the second crystal piece 112 each have corner portions C1 to C4. Taking the first crystal piece 111 as an example, corners C1 and C2 are located on the short side closer to the second crosspiece 122, and corners C3 and C4 are located on the short side closer to the first crosspiece 121. The corners C1 and C4 are located diagonally to each other.

The first crystal piece 111 is supported by the first crosspiece 121 via the first support 131, and the second crystal piece 112 is supported by the second crosspiece 122 via the second support 132. That is, the first crosspiece 121 that supports the first crystal piece 111 is a crosspiece located on one side of the second direction D2, that is, the positive direction side with respect to the first crystal piece 111. All the crystal pieces 110 of the collective substrate 100 are similarly supported by the crosspieces 120 located on one side in the second direction D2, that is, the positive direction side. The first support portion 131 supports the first crystal piece 111 on the first crosspiece 121 at two points between the corner portion C3 and the end side 121b and between the corner portion C4 and the end side 121b. . Similarly, the second support portion 132 supports the second crystal piece 112 on the second crosspiece 122 at two points. The first protrusion 141 protrudes from the end side 121a, and the second protrusion 142 protrudes from the end side 122a toward the first crosspiece 121. Further, the second protrusion 142 has a tip 142 a that is separated from the first crystal piece 111. The first protrusion 141 and the second protrusion 142 are arranged in the first direction D1 with a space between each other, and are adjacent to each other in the second direction D2.

The tip 142a of the second protrusion 142 is an end extending in the first direction D1 in the configuration example illustrated in FIG. The second projecting portion 142 projects toward the space between one adjacent first crystal piece 111 and the other first crystal piece 111. That is, the second protrusion 142 protrudes so that the tip 142a approaches both the corner C1 of one first crystal piece 111 and the corner C2 of the other first crystal piece 111. The second protrusion 142 preferably has at least its tip 142a to avoid a space between the first crystal piece 111 and the second crosspiece 122, and more preferably the entire second protrusion 142 has the first crystal piece 111. And projecting to avoid a space between the second crosspiece 122. The second protrusion 142 is preferably separated from the space between the first crystal pieces 111 adjacent in the first direction D1. That is, the second protrusion 142 is not aligned with the first crystal piece 111 in the first direction D1. That is, the gap G2 in the second direction D2 of the space between the short side of the first crystal piece 111 on the second crosspiece 122 side and the end side 122a of the second crosspiece 122 is the corner of the first crystal piece 111. It is constant from C1 to the corner C2. Further, the gap G1 in the first direction D1 of the space between the long sides facing each other of the adjacent first crystal pieces 111 is constant from the corner C1 to the corner C3 of the first crystal piece 111. When the space interval between the tip 142a and the corner C1 is G3 and the space interval between the tip 142a and the corner C2 is G4, the interval G3 is equal to the interval G4, and the interval It is smaller than G1 and G2 (G3 = G4, G3 <G1, G3 <G2).

The above describes the outer shape of the collective substrate 100 formed in steps S11 to S15 when viewed in plan from the normal line of the main surface of the collective substrate 100. At this time, the main surface of the collective substrate 100 is a surface parallel to the surface specified by the first direction D1 and the second direction D2 (hereinafter referred to as “D1D2 surface”), and the main surface 110a of the crystal piece 110. It is almost parallel to. Next, the mesa structure of the crystal piece 110 formed in step S16 will be described. In FIG. 3, the main surface of the first crystal piece 111 is indicated by reference numeral 111a, and the main surface of the second crystal piece 112 is indicated by reference numeral 112a.

Specifically, when the main surface 110a is viewed in plan, the quartz crystal piece 110 has a vibrating portion 117 including the center, and a thickness in the normal direction of the main surface 110a that is located outside the vibrating portion 117 is a vibrating portion. It has a peripheral edge different from 117. The peripheral edge has a first peripheral edge 118 and a second peripheral edge 119. The vibration part 117 has a short side parallel to the first direction D1 and a long side parallel to the second direction D2. The first peripheral portion 118 and the second peripheral portion 119 are provided on both sides in the long side direction of the crystal piece 110 with respect to the vibrating portion 117. The first peripheral portion 118 and the second peripheral portion 119 correspond to the peripheral portion of the crystal piece 110. Taking the first crystal piece 111 as an example, the first peripheral edge portion 118 includes a short side on the side connected to the first crosspiece 121 of the first crystal piece 111 and is more first than the vibrating portion 117. Located on the side close to the crosspiece 121. Further, the second peripheral edge 119 includes a short side opposite to the peripheral edge 118 of the first crystal piece 111 and is located closer to the second crosspiece 122 than the vibrating part 117. The positional relationship among the vibrating part 117, the first peripheral part 118, and the second peripheral part 119 is the same in the other crystal pieces 110 such as the second crystal piece 112.

The vibrating portion 117 has a thickness different from that of the first peripheral portion 118 and the second peripheral portion 119 (hereinafter, “thickness” refers to a thickness parallel to the normal direction of the main surface 110a. Other “thicknesses”. The same shall apply to "." Specifically, the thickness of the first peripheral edge portion 118 is smaller than the thickness of the vibrating portion 117. The thickness of the second peripheral edge 119 is also smaller than the thickness of the vibration part 117. Further, the crystal piece 110 is provided with steps at the boundary between the vibrating portion 117 and the first peripheral portion 118 and the boundary between the vibrating portion 117 and the second peripheral portion 119 in the long side direction of the crystal piece 110. . This level difference extends along the short side direction of the crystal piece 110. In the crystal piece 110, which is a crystal of quartz, this step is formed with a predetermined tilt angle that depends on the crystal orientation of the crystal. In addition, although the thickness of each of the 1st peripheral part 118 and the 2nd peripheral part 119 is the same as an example, you may differ. The width W2 of the first peripheral edge 118 in the second direction D2 may be larger than the width W1 of the second peripheral edge 119 in the second direction D2. That is, the area of the first peripheral edge 118 may be larger than the area of the second peripheral edge 119 when the main surface 110a of the crystal piece 110 is viewed in plan.

In the present embodiment, the mode has been described by taking as an example a crystal piece having a mesa structure in which the vibration part is thicker than the peripheral part. However, the present invention may be applied to a quartz piece having an inverted mesa structure in which the vibration part is thinner than the peripheral part. In addition, the present invention may be applied to a quartz piece having a convex structure or a bevel structure in which changes in thickness (steps) between the vibrating portion and the peripheral portion change continuously.

Next, the excitation electrode forming process will be described with reference to FIG. Note that S21 to S25 of the excitation electrode forming step are the same as steps S11 to S15 of the crystal piece forming step, and description of similar parts in each step is omitted, and only different parts are described. First,

metal layers

200 and 300 are formed on both

main surfaces

101 and 102 of the aggregate substrate 100 (S21). The collective substrate 100 used at this time is shown in FIG. At this time, the metal layer is not necessarily formed on the entire

main surfaces

101 and 102 of the collective substrate 100 (that is, the main surfaces of the crystal piece 110, the crosspiece 120, and the support portion 130). What is necessary is just to be formed in both main surfaces. In order to obtain electrical continuity between the two main surfaces, a metal layer may be provided on the side surfaces connected to the two main surfaces.

Next, photoresist layers 400 and 500 are formed on the metal layers 200 and 300 (S22). At this time, a photoresist layer 400 is first formed by spin coating on the main surface 101 on the side of the aggregate substrate 100 where the metal layer 200 is provided. Next, a photoresist layer 400 is formed on the main surface 102 of the aggregate substrate 100 on which the metal layer 300 is provided by a spin coating method. The formation of the photoresist layer in the excitation electrode forming step will be described with reference to FIGS. 4 and 5 by taking the application of the photoresist solution 501 as an example. The main surface 110a of the crystal piece 110 illustrated in FIG. 3 is a surface located on the main surface 102 side of the collective substrate 100.

As shown in FIG. 4, the collective substrate 100 is placed on a turntable 610 so that the metal layer 300 is on the upper surface, and a photoresist solution 501 in which a photoresist is dissolved in a solvent is dropped onto the center 103 of the main surface 102. In order to make the thickness of the photoresist layer 500 uniform, the collective substrate 100 is installed such that the center 103 is located on the extension line of the rotation shaft 620 of the turntable 610. Next, the turntable 610 is rotated at the rotation speed R1 around the rotation shaft 620 so that the photoresist solution 501 spreads with a uniform thickness.

As shown in FIG. 5, the photoresist solution 501 that receives the centrifugal force moves between the first crystal piece 111 and the second crosspiece 122 via the flow path 502 and the flow path 503. The channel 502 is a channel formed between the corner C2 of the first crystal piece 111 and the tip 142a of the second protrusion 142 because the interval G4 is sufficiently smaller than the intervals G1 and G2. The flow path 503 is a path formed between the corner C2 and the tip 142a because the gap G3 is sufficiently smaller than the gaps G1 and G2. The formation of such a flow path is attributed to the fact that if the space formed in the collective substrate 100 is sufficiently small, the photoresist solution can be spread over the space by surface tension. Since the

flow paths

502 and 503 are formed by the second projecting portions 142, the photoresist solution 501 is prevented from forming a liquid pool in the first crystal piece 111, and the thickness uniformity of the photoresist layer 500 is improved. To do. At this time, if the second protrusion 142 facing the corner C2 at the interval G4 is substantially trapezoidal, the angle of the corner of the second protrusion 142 facing the corner C2 becomes an obtuse angle.

Next, the photoresist layers 400 and 500 are exposed and developed to form an electrode pattern (S23). As shown in FIG. 6, taking the photoresist layer 500 as an example, the electrode pattern 510 covers regions that will be the excitation electrode 314, the extraction electrode 315, and the connection electrode 316. The photoresist layer 500 in the region other than the electrode pattern 510 is removed. In the previous step S22, the thickness unevenness of the photoresist layer 500 due to the accumulation of the photoresist solution 501 can be reduced, so that a photoresist residue is generated in which a thick portion of the photoresist layer 500 is not completely removed by exposure and development. Can be suppressed.

Next, the metal layers 200 and 300 are removed according to the electrode pattern to form an excitation electrode (S24). As shown in FIG. 6, taking the metal layer 300 as an example, the exposed metal layer 300 around the excitation electrode 314, the extraction electrode 315, and the connection electrode 316 covered with the electrode pattern 510 is removed. The excitation electrode 314 is formed on the vibration unit 117. In addition, the extraction electrode 315 and the connection electrode 316 are formed on the first peripheral edge 118. The excitation electrode 314, the extraction electrode 315, and the connection electrode 316 are continuously connected to each other and electrically connected. The extraction electrode 315 and the connection electrode 316 are formed simultaneously with the excitation electrode 314. Note that the extraction electrode 315 and the connection electrode 316 can be formed in a step different from the formation of the excitation electrode 314.

Next, the photoresist layers 400 and 500 are removed (S25). As shown in FIG. 6, taking the photoresist layer 500 as an example, the removed photoresist layer 500 corresponds to the electrode pattern 510. The excitation electrode forming process is thus completed. Although illustration is omitted, after the step S25, a step of separating the piezoelectric substrates from the support portions and separating them into pieces is performed. The piezoelectric substrate is separated into pieces by, for example, being broken from the support portion. The piezoelectric substrate separated from the collective substrate is obtained as a piezoelectric vibration element.

As described above, according to one aspect of the present invention, a step of preparing the piezoelectric substrate (quartz substrate) 99 and a plurality of bars arranged in the second direction D2 extending in the first direction D1 and intersecting the first direction D1. A plurality of piezoelectric pieces (first crystal pieces) 111 that are positioned between the first crosspiece portion 120 and the first crosspiece portion 121 and the second crosspiece portion 122 that are adjacent to each other in the plurality of crosspiece portions 120 and arranged in the first direction D1. A plurality of support portions 131 that support the piezoelectric piece 111 on the first crosspiece 121 and a protrusion 142 that protrudes from the second crosspiece 122 toward the first crosspiece 121 and has a tip that is separated from the piezoelectric piece 111. A step of forming the collective substrate 100 provided from the piezoelectric substrate 99, a step of forming the metal layer 300 on at least the main surface 111a of the piezoelectric piece 111 of the collective substrate 100, and a solution containing a photoresist on the metal layer 300. Apply and photoresist 500, exposing and developing the photoresist layer 500 to form an electrode pattern 510, removing the metal layer 300 in accordance with the electrode pattern 510, and exciting electrode 314 on main surface 111a of piezoelectric piece 111. Forming a piezoelectric vibration element.

According to the above embodiment, in the excitation electrode forming step, the protrusions form the flow path of the photoresist solution, and therefore, when the photoresist layer is applied, the photoresist solution pools at the corners of the piezoelectric piece. Occurrence can be suppressed. That is, the uniformity of the thickness of the photoresist layer can be improved, and the generation of photoresist residues in the development process can be suppressed. By reducing the photoresist residue, it is possible to suppress the formation of unnecessary electrodes due to poor etching of the metal layer. That is, it is possible to provide a method for manufacturing a piezoelectric vibration element that can suppress fluctuations in frequency characteristics.

In addition, if it is a step after the piezoelectric piece (crystal piece) 110, the crosspiece 120, the support portion 130, and the protruding portion 140 are formed on the quartz substrate 99 and includes a step of applying a photoresist solution, excitation is performed. Even if it is another process without being limited to the electrode forming process, it is possible to suppress the generation of the photoresist pool as in the present embodiment. For example, in step S16 of processing the piezoelectric piece 110 into a mesa structure, it is possible to suppress the occurrence of a crystal piece shape defect caused by the photoresist residue.

The first crosspiece 121 is a crosspiece located on one side in the second direction D2 of the two

crosspieces

121 and 122 adjacent to each other, that is, on the positive direction side. ) 110 may be supported by the first crosspiece 121 located on one side in the second direction D2, that is, the positive direction side, via the support 131. Thereby, in the singulation process of separating the piezoelectric pieces from the collective substrate to form the piezoelectric vibration element, for example, all the piezoelectric pieces can be folded by applying a force from the same direction without changing the orientation of the collective substrate. That is, the singulation process can be simplified.

The step of forming the photoresist layer 500 may include a spin coating method. The spin coating method is more likely to cause photoresist accumulation due to surface irregularities and gaps of the piezoelectric substrate than the spray coating method, etc., but according to this embodiment, even if the spin coating method is used, the occurrence of photoresist accumulation occurs. Can be suppressed.

The protruding portion 142 may protrude toward the corner portions C1 and C2 of the piezoelectric piece (first crystal piece) 111. Accordingly, a flow path can be formed between the crosspiece and the corner portion where the photoresist is liable to be generated via the protruding portion, and the thickness of the photoresist layer can be made more uniform.

The protrusion 142 is provided between the adjacent piezoelectric pieces 111 arranged in the first direction D1 so as to avoid a space between the piezoelectric piece (first crystal piece) 111 and the second crosspiece 122 in the second direction D2. You may protrude toward the space. Thereby, the etching rate of the short side of the piezoelectric piece becomes constant, and the distortion of the short side on the second crosspiece side of the piezoelectric piece can be suppressed.

The protrusion 142 may be separated from the space between adjacent piezoelectric pieces (first crystal pieces) 111 in the first direction D1. Thereby, the etching rate of the long side of the piezoelectric piece becomes constant, and the distortion of the long side of the adjacent piezoelectric pieces facing each other can be suppressed.

The protrusion 142 has a first corner C1 of one of the two piezoelectric pieces adjacent in the first direction D1 in the plurality of piezoelectric pieces (first crystal pieces) 111 and a second corner of the other piezoelectric piece. You may protrude so that both may approach part C2. Accordingly, the gaps G3 and G4 between the first corner C1 and the second corner C2 and the protrusion 142 are smaller than the gap G2 between the first corner C1 and the second corner C2 and the

crosspieces

121 and 122. . As a result, a gap G3 close to the first corner C1 and the obtuse corner of the protrusion 142 forms a fluid resist flow path, and the second corner C2 and the protrusion 142 A flow path can be formed even between them. That is, the occurrence of photoresist accumulation can be suppressed more effectively. The projecting portion 142 has a substantially trapezoidal shape when the main surface 111a is viewed in plan, and the width dimension in the first direction D1 decreases as the projecting portion 142 projects from the crosspiece portion in the second direction D2. That is, the corner on the tip 142a side of the protrusion 142 is configured to be an obtuse angle. According to this, there is an effect that the flow rate at which the photoresist solution can be discharged from the corner portion of the piezoelectric piece 111 to the corner portion of the protruding portion 142 can be increased as compared with the case where the corner portion of the protruding portion 142 has a right angle and an acute angle.

The piezoelectric piece (first crystal piece) 111 is located at the center when the main surface 111a is viewed in plan view, and the piezoelectric part 111 is located outside the vibrating part 117 and is located outside the vibrating part 117. You may have the peripheral part 118,119 in which the thickness in the normal line direction of the surface 111a differs from the vibration part 117. That is, even if the surface unevenness of the collective substrate to which the photoresist solution is applied is increased and the wet spreading of the photoresist solution is inhibited, the occurrence of photoresist accumulation can be suppressed.

The

peripheral edge portions

118 and 119 are thinner than the vibrating portion 117, and the

peripheral edge portions

118 and 119 are located closer to the first crosspiece 121 than the vibrating portion 117, and the vibrating portion A second peripheral edge 119 located closer to the second crosspiece 122 than 117, and the area of the second peripheral edge 119 may be smaller than the area of the first peripheral edge 118. As described above, even in the case of a piezoelectric piece having a so-called mesa structure, it is possible to suppress the occurrence of photoresist accumulation due to the surface unevenness of the piezoelectric piece.

Furthermore, a step of separating the piezoelectric pieces (first crystal pieces) 111 from the support portions 131 to form piezoelectric vibration elements may be included. Since the piezoelectric vibration element manufactured through the above steps can suppress fluctuations in frequency characteristics, the generation rate of defective products can be suppressed and the manufacturing cost can be reduced.

Next, a configuration example of a piezoelectric vibrator manufactured using the piezoelectric vibration element according to the present embodiment will be described with reference to FIGS. 7 and 8. In the following description, a quartz resonator (Quartz Crystal Resonator Unit) using a quartz piece (Quartz Crystal Element) as a piezoelectric substrate will be described as an example. Here, FIG. 7 is an exploded perspective view showing an example of a piezoelectric vibrator manufactured using the present embodiment. 8 is a cross-sectional view taken along line VIII-VIII in FIG.

As shown in FIG. 7, the crystal resonator 1 includes a crystal resonator element (Quartz Crystal Resonator) 10, a lid member 20, and a base member 30. The lid member 20 and the base member 30 are holders for housing the crystal resonator element 10. In the example shown in FIG. 7, the lid member 20 has a concave shape, and the base member 30 has a flat plate shape. Specifically, the lid member 20 has a box shape having an opening on the base member 30 side. The lid member 20 may be flat and the base member 30 may be concave.

The crystal resonator element 10 includes an AT-cut type crystal piece (Quartz Crystal Element) 11. The AT-cut crystal piece 11 has an X-axis, a Y-axis, and a Z-axis which are crystal axes of artificial quartz, and the Y-axis and the Z-axis are 35 degrees 15 minutes around the X-axis from the Y-axis to the Z-axis. When the axes rotated by ± 1 minute 30 seconds are defined as the Y ′ axis and the Z ′ axis, respectively, a plane parallel to the plane specified by the X axis and the Z ′ axis (hereinafter referred to as “XZ ′ plane”). It was cut out as the main surface. The crystal piece 11 has a rectangular shape on the XZ ′ plane, a long side direction in which a long side parallel to the X-axis direction extends, a short side direction in which a short side parallel to the Z′-axis direction extends, and Y A thickness direction parallel to the 'axis direction extends. The crystal piece 11 has a first main surface 12a and a second main surface 12b which are XZ ′ surfaces facing each other, and an end surface 12c extending along the short side and connecting the two main surfaces.

A quartz resonator element using an AT-cut quartz piece has high frequency stability over a wide temperature range, is excellent in aging characteristics, and can be manufactured at low cost. Further, the AT-cut quartz crystal resonator element uses a thickness shear vibration mode as a main vibration. In addition, you may apply different cuts (for example, BT cut etc.) other than AT cut for the cut angle of a crystal piece. Further, the crystal piece 11 has a rectangular shape on the XZ ′ plane, but is not limited to this, and may be a comb-teeth shape.

The crystal resonator element 10 includes a first excitation electrode 14a and a second excitation electrode 14b that constitute a pair of electrodes. The first excitation electrode 14a is provided at the center of the first main surface 12a. The second excitation electrode 14b is provided at the center of the second main surface 12b. The first excitation electrode 14a and the second excitation electrode 14b are provided to face each other with the crystal piece 11 in between. The first excitation electrode 14a and the second excitation electrode 14b are disposed so as to substantially overlap each other on the XZ ′ plane.

The crystal resonator element 10 has a pair of

extraction electrodes

15a and 15b and a pair of

connection electrodes

16a and 16b. The connection electrode 16a is electrically connected to the first excitation electrode 14a via the extraction electrode 15a. The connection electrode 16b is electrically connected to the second excitation electrode 14b through the extraction electrode 15b. The

connection electrodes

16 a and 16 b are terminals for electrically connecting the first excitation electrode 14 a and the second excitation electrode 14 b to the base member 30. On the first main surface 12a, the first excitation electrode 14a, the extraction electrode 15a, and the connection electrode 16a are provided continuously. Further, the connection electrode 16a extends over the end surface 12c and the second main surface 12b. Similarly, on the second main surface 12b, the second excitation electrode 14b, the extraction electrode 15b, and the connection electrode 16b are continuously provided. The connection electrode 16b extends over the end surface 12c and the first main surface 12a. In the configuration example shown in FIG. 7, the

connection electrodes

16 a and 16 b are arranged along the short side direction (Z′-axis direction) of the crystal piece 11. The

connection electrodes

16a and 16b may be arranged along the long side direction (X-axis direction) of the crystal piece 11. Further, the

connection electrodes

16 a and 16 b may be arranged near the center of the long side or the short side of the crystal piece 11, or may be arranged on different sides of the crystal piece 11.

The

conductive holding members

36 a and 36 b electrically connect the

connection electrodes

16 a and 16 b to the pair of electrode pads of the base member 30, respectively. The

conductive holding members

36a and 36b are formed of a conductive adhesive such as an ultraviolet curable resin, for example. For example, the conductive holding member 36a is in contact with the connection electrodes 16a on the second main surface 12b and the end surface 12c. The same applies to the conductive holding member 36b. By increasing the contact area between the conductive holding member and the connection electrode, the conductivity between the electrode pad and the connection electrode can be improved.

The lid member 20 is bonded to the base member 30, and thereby accommodates the crystal resonator element 10 in the internal space 26. The lid member 20 has an inner surface 24 and an outer surface 25, and has a concave shape that opens toward the third main surface 32 a of the base member 30. The lid member 20 has a top surface portion 21 that faces the third main surface 32 a of the base member 30, and a side wall that is connected to the outer edge of the top surface portion 21 and extends in a direction intersecting the main surface of the top surface portion 21. Part 22. The lid member 20 has a facing surface 23 that faces the third main surface 32 a of the base member 30 at the concave opening edge (end surface of the side wall portion 22), and this facing surface 23 surrounds the periphery of the crystal resonator element 10. It extends like a frame. The material of the lid member 20 is not particularly limited, but is made of a conductive material such as metal. According to this, the electromagnetic shielding function which shields electromagnetic waves can be added to the lid member 20.

The base member 30 supports the crystal resonator element 10 so that it can be excited. Specifically, the crystal resonator element 10 is held on the third main surface 32a of the base member 30 through the

conductive holding members

36a and 36b so as to be able to be excited. The base member 30 has a base 31. The base 31 has a third main surface 32a and a fourth main surface 32b that are XZ ′ surfaces facing each other. The base 31 is a sintered material such as insulating ceramic (alumina).

The base member 30 has

electrode pads

33a and 33b provided on the third main surface 32a and

external electrodes

35a, 35b, 35c and 35d provided on the second main surface. The

electrode pads

33 a and 33 b are terminals for electrically connecting the base member 30 and the crystal resonator element 10. The

external electrodes

35a, 35b, 35c, and 35d are terminals for electrically connecting a mounting substrate (not shown) and the crystal unit 1. The electrode pad 33a is electrically connected to the external electrode 35a via a via electrode 34a extending in the Y′-axis direction, and the electrode pad 33b is an external electrode via a via electrode 34b extending in the Y′-axis direction. It is electrically connected to 35b. The via

electrodes

34a and 34b are formed in via holes that penetrate the base 31 in the Y′-axis direction.

The

electrode pads

33a and 33b of the base member 30 are provided in the vicinity of the short side of the base member 30 on the X axis negative direction side on the third main surface 32a, away from the short side of the base member 30 and in the short side direction. Are arranged along. The electrode pad 33a is connected to the connection electrode 16a of the crystal resonator element 10 via the conductive holding member 36a, while the electrode pad 33b is connected to the connection electrode 16b of the crystal resonator element 10 via the conductive holding member 36b. Is done.

The plurality of

external electrodes

35a, 35b, 35c, and 35d are provided in the vicinity of each corner of the fourth main surface 32b. For example, the

external electrodes

35a and 35b are disposed immediately below the

electrode pads

33a and 33b. Accordingly, the

external electrodes

35a and 35b can be electrically connected to the

electrode pads

33a and 33b by the via

electrodes

34a and 34b extending in the Y′-axis direction. Out of the four external electrodes 35a to 35d, the

external electrodes

35a and 35b arranged near the short side of the base member 30 on the X axis negative direction side are input / output electrodes to which an input / output signal of the crystal resonator element 10 is supplied. is there. The

external electrodes

35c and 35d arranged near the short side of the base member 30 on the X axis positive direction side are dummy electrodes to which input / output signals of the crystal resonator element 10 are not supplied. Such dummy electrodes are not supplied with input / output signals of other electronic elements on a mounting board (not shown) on which the crystal unit 1 is mounted. Alternatively, the

external electrodes

35c and 35d may be grounding electrodes to which a ground potential is supplied. By connecting the lid member 20 to the

external electrodes

35c and 35d, which are grounding electrodes, the electromagnetic shielding function of the lid member 20 can be improved.

A sealing frame 37 is provided on the third main surface 32 a of the base 31. For example, the sealing frame 37 has a rectangular frame shape when the third main surface 32a is viewed in plan. The

electrode pads

33 a and 33 b are disposed inside the sealing frame 37, and the sealing frame 37 is provided so as to surround the crystal resonator element 10. The sealing frame 37 is made of a conductive material. A joining member 40 described later is provided on the sealing frame 37, whereby the lid member 20 is joined to the base member 30 via the joining member 40 and the sealing frame 37. For example, the

electrode pads

33a and 33b, the external electrodes 35a to 35d, and the sealing frame 37 of the base member 30 are all made of a metal film. In the metal film, for example, a molybdenum (Mo) layer, a nickel (Ni) layer, and a gold (Au) layer are laminated in this order from the side contacting the base 31 (lower layer) to the side away from the base 31 (upper layer). Has been configured. The via

electrodes

34a and 34b can be formed by filling the via hole of the base 31 with a metal material such as molybdenum (Mo).

When both the lid member 20 and the base member 30 are joined via the sealing frame 37 and the joining member 40, the quartz resonator element 10 is surrounded by the lid member 20 and the base member 30 (cavity). 26 is sealed. In this case, the pressure in the internal space 26 is preferably in a vacuum state lower than the atmospheric pressure, so that the frequency characteristics of the crystal resonator 1 change with time due to oxidation of the first excitation electrode 14a and the second excitation electrode 14b. Can be reduced.

The joining member 40 is provided over the entire circumference of the lid member 20 and the base member 30. Specifically, the joining member 40 is provided on the sealing frame 37. Since the sealing frame 37 and the joining member 40 are interposed between the facing surface 23 of the side wall portion 22 of the lid member 20 and the third main surface 32a of the base member 30, the crystal resonator element 10 is covered with the lid member 20. And the base member 30 is sealed.

In the crystal resonator element 10 according to this configuration example, one end of the crystal piece 11 in the long side direction (the end on the side where the

conductive holding members

36a and 36b are disposed) is a fixed end, and the other end is a free end. It has become. In addition, the crystal resonator element 10, the lid member 20, and the base member 30 have rectangular shapes on the XZ ′ plane, and the long side direction and the short side direction are the same.

However, the position of the fixed end of the crystal resonator element 10 is not particularly limited, and may be fixed to the base member 30 at both ends in the long side direction of the crystal piece 11. In this case, the crystal resonator element 10 and the electrodes of the base member 30 may be formed in such a manner that the crystal resonator element 10 is fixed at both ends of the crystal piece 11 in the long side direction.

In the crystal resonator 1 according to this configuration example, an alternating electric field is applied between the pair of

excitation electrodes

14 a and 14 b in the crystal resonator element 10 via the

external electrodes

35 a and 35 b of the base member 30. As a result, the crystal piece 11 vibrates in a predetermined vibration mode such as a thickness shear vibration mode, and resonance characteristics associated with the vibration are obtained.

When manufacturing a crystal resonator as described above, fluctuations in the performance (excitation frequency) of the crystal resonator can be suppressed by using the manufacturing method according to this embodiment.

Next, a modification of the piezoelectric vibrator will be described. In the following modified example, description of matters common to the above embodiment is omitted, and only different points will be described. In particular, the same operation effect by the same configuration will not be mentioned sequentially.

<Modification>
FIG. 9 is a perspective view of a piezoelectric vibration element according to a modification of the present invention. The modification is different from the configuration example shown in FIG. 7 in that the shape of the piezoelectric vibration element 210 is a tuning fork type. Specifically, the piezoelectric substrate 211 has two tuning

fork arm portions

219a and 219b arranged in parallel to each other. The tuning

fork arm portions

219a and 219b extend in the X-axis direction, are aligned in the Z′-axis direction, and are connected to each other by a connecting portion 219c on the end face 212c side. In the tuning fork arm portion 219a, excitation electrodes 214a are provided on a pair of main surfaces that are parallel to the XZ 'plane and face each other, and excitation electrodes 214b intersect the pair of main surfaces and face each other. Is provided. In the tuning fork arm portion 219b, excitation electrodes 214b are provided on a pair of main surfaces, respectively, and excitation electrodes 214a are provided on a pair of side end surfaces. The configuration of the piezoelectric vibration element 210 is not particularly limited, and the shape of the tuning fork arm, the arrangement of the excitation electrodes, and the like may be different.

Even in the above modification, the same effect as described above can be obtained.

The embodiment described above is for facilitating understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed / improved without departing from the spirit thereof, and the present invention includes equivalents thereof. In other words, those obtained by appropriately modifying the design of each embodiment by those skilled in the art are also included in the scope of the present invention as long as they include the features of the present invention. For example, each element included in each embodiment and its arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be changed as appropriate. In addition, each element included in each embodiment can be combined as much as technically possible, and combinations thereof are included in the scope of the present invention as long as they include the features of the present invention.

99 ... Piezoelectric substrate (quartz substrate) 100 ... Aggregate substrate 110 ... Crystal piece (piezoelectric piece)
DESCRIPTION OF SYMBOLS 111 ... 1st crystal piece 112 ... 2nd crystal piece 120 ... Crosspiece 121 ... 1st crosspiece 122 ... 2nd crosspiece 130 ... Support part 131 ... 1st support part 132 ... 2nd support part 140 ... Protrusion part 141 ... 1st protrusion 142 ... 2nd protrusion 142a ... tip C1, C2, C3, C4 ...

corner

200, 300 ...

metal layer

400, 500 ... photoresist layer 501 ...

photoresist solution

502, 503 ... flow path 510 ... electrode Pattern 314 ... Excitation electrode 315 ... Extraction electrode 316 ... Connection electrode

Claims

Preparing a piezoelectric substrate;
A plurality of crosspieces extending in a first direction and arranged in a second direction intersecting the first direction, and located between adjacent first and second crosspieces in the plurality of crosspieces, A plurality of piezoelectric pieces arranged in a first direction; a plurality of support portions for supporting the plurality of piezoelectric pieces on the first crosspiece; and a projection protruding from the second crosspiece toward the first crosspiece and from the piezoelectric pieces. Forming a collective substrate from the piezoelectric substrate comprising a protrusion having a distant tip; and
Forming a metal layer on at least a main surface of the piezoelectric piece of the aggregate substrate;
Applying a solution containing a photoresist on the metal layer to form a photoresist layer;
Exposing and developing the photoresist layer to form an electrode pattern;
Removing the metal layer according to the electrode pattern to form an excitation electrode on the main surface of the piezoelectric piece;
A method for manufacturing a piezoelectric vibration element, comprising:
The first crosspiece is a crosspiece located on one side in the second direction among the two crosspieces adjacent to each other, and all the piezoelectric pieces of the collective substrate are connected to the first via the support. Supported by the first crosspiece located on the one side in two directions,
The method for manufacturing a piezoelectric vibration element according to claim 1.
The step of forming the photoresist layer includes a spin coating method.
The method for manufacturing a piezoelectric vibration element according to claim 1.
The protruding portion protrudes toward a corner portion of the piezoelectric piece.
The manufacturing method of the piezoelectric vibration element of any one of Claim 1 to 3.
The protruding portion protrudes toward a space between adjacent piezoelectric pieces arranged in the first direction so as to avoid a space between the piezoelectric piece and the second crosspiece in the second direction. Yes,
The manufacturing method of the piezoelectric vibration element of any one of Claim 1 to 4.
The protrusion is separated from a space between the adjacent piezoelectric pieces in the first direction.
The method for manufacturing a piezoelectric vibration element according to claim 1.
The protruding portion protrudes so as to approach both the first corner of one piezoelectric piece and the second corner of the other piezoelectric piece of two adjacent piezoelectric pieces in the plurality of piezoelectric pieces. ,
The method for manufacturing a piezoelectric vibration element according to claim 1.
When the piezoelectric piece is viewed in plan from the main surface,
A vibrating part located in the center and where the excitation electrode is formed;
A peripheral edge located on the outer side of the vibrating portion and having a thickness in the normal direction of the principal surface of the piezoelectric piece that is different from the vibrating portion;
The manufacturing method of the piezoelectric vibration element of any one of Claim 1 to 7.
The peripheral edge is thinner than the vibrating part,
A first peripheral portion located on a side closer to the first crosspiece portion than the vibrating portion; and a second peripheral portion located on a side closer to the second crosspiece portion than the vibrating portion. Have
The area of the second peripheral edge is smaller than the area of the first peripheral edge,
The method for manufacturing a piezoelectric vibration element according to claim 8.
Further, the method includes a step of separating the piezoelectric pieces from the support portions to form piezoelectric vibration elements.
The method for manufacturing a piezoelectric vibration element according to claim 1.