JP2016174328A - Wafer manufacturing method and wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer manufacturing method and a wafer, which enable singulation of oscillation elements from a wafer.SOLUTION: A wafer manufacturing method of the present embodiment includes: a first etching step of etching a crystal substrate 10 as a wafer to form a first region 20 which is a region corresponding to a thin part and simultaneously half-etching a region corresponding to an outer shape of an oscillation element 12 by a depth of the thin part; and a second etching step of etching the half-etched regions corresponding to the outer shapes to form outer shapes of individual oscillation elements 12.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a wafer manufacturing method and a wafer.

  AT-cut quartz resonators that excite the thickness shear vibration, which is the main vibration, exhibit cubic curves that are suitable for miniaturization and higher frequency and have excellent frequency-temperature characteristics, so they are used in various fields such as oscillators and electronic equipment. ing. In particular, in recent years, as the processing speed of transmission communication equipment and OA equipment has been increased or the capacity of communication data and processing volume has been increased, the AT cut crystal resonator as a reference frequency signal source used therefor has a higher frequency. There is an increasing demand for conversion. Therefore, the frequency is increased by reducing the thickness of the vibration part excited by the thickness shear vibration.

  In Patent Document 1, a quartz resonator element having a high frequency with an inverted mesa structure having a thin rectangular vibrating portion and a thick portion connected to three sides of the vibrating portion is provided. A method of manufacturing a piezoelectric substrate is disclosed in which after forming an inverted mesa portion by an etching method, the outer shape of the element is processed into individual pieces. Patent Document 2 discloses a piezoelectric vibration element having an inverted mesa structure having a thin rectangular vibration part and a thick part connected to two sides of the vibration part, and a manufacturing method thereof. . Patent Document 3 discloses a reverse mesa having a thin rectangular vibration part and a thick part connected to two sides of the vibration part, and a part of the thick part is cut obliquely. A vibrating element having a structure and a manufacturing method thereof are disclosed.

JP 2006-203700 A JP 2013-042440 A JP 2014-138413 A

  However, in the method for manufacturing a crystal resonator element described in Patent Documents 1 to 3, depending on the interval between two adjacent crystal resonator elements of a plurality of crystal resonator elements arranged on the wafer, the two crystal resonator elements may be spaced apart from each other. There was a problem that a residue due to crystal planes such as r-plane caused by etching anisotropy of quartz was generated and could not be singulated.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A wafer manufacturing method according to this application example includes a thin part and a thick part that is integrated with the outer edge except for a part of the outer edge of the thin part, and is thicker than the thin part. And a plurality of vibration elements including a plurality of vibration elements connected to a frame, wherein the wafer is etched to form a region corresponding to the thin portion and to correspond to the outer shape of the vibration element. A first etching step of simultaneously half-etching the region by the depth of the thin-walled portion; a second etching step of etching a region corresponding to the half-etched outer shape to form the outer shape of the piece of the vibration element; , Including.

  According to this application example, before the second etching step for forming the outer shape of the vibration element, in the first etching step, the etching for forming the thin portion and the part of the thick portion for separation into pieces are simultaneously performed. Since half-etching is performed, the time for etching in the second etching process is increased, the generation of etching residues due to crystal planes due to the etching anisotropy of the wafer material can be reduced, and the vibration elements can be singulated.

Application Example 2 A wafer manufacturing method according to this application example is integrated with a first region including a vibration region that vibrates by thickness shear vibration, and an outer edge of the first region, and is thicker than the first region. A thick second region, and the outer edge of the first region includes one first outer edge orthogonal to the vibration direction of the thickness-shear vibration and the other first outer edge, and one of the outer edges along the vibration direction. A second outer edge and the other second outer edge, wherein the one first outer edge is spaced apart from the other first outer edge in the vibration direction, and the one second outer edge is the other second outer edge. And the second region has a first thick portion connected to the one first outer edge and a second thickness connected to the one second outer edge. A vibration element including a meat part and a third thick part connected to the first thick part and the second thick part is a front element. A plurality of outer edges arranged in a direction orthogonal to the vibration direction and parallel to the one second outer edge side opposite to the one second outer edge side of the second thick portion of the first vibration element And the third thick portion of the wafer that is spaced apart from the other second outer edge and the first thick portion of the first region of the second vibrating element arranged next to each other by an interval of a length W. A manufacturing method comprising: a preparation step for preparing a wafer; a protective film application step for applying a protective film to the surface of the wafer; and a length along a direction orthogonal to the vibration direction, along the vibration direction. An opening portion including a first opening whose length is equal to or longer than the length of the vibration element along the vibration direction and a second opening corresponding to the first region is orthogonal to the vibration direction. An exposure step of exposing the protective film using a plurality of masks arranged in a direction. When the thickness of the wafer was determined as t, and satisfies a relationship of ^{0.029 <(W / t 2)} <0.033.

According to this application example, the length W of the interval between the opposing outer edges of adjacent vibrating elements is a length satisfying the relationship of 0.029 <(W / t ² ) <0.033 with respect to the thickness t of the wafer. After exposure using a mask having an opening to form an etching pattern, between adjacent vibration elements is etched in a first etching step. By doing so, it is possible to increase the time for etching between the adjacent vibration elements in the second etching step, and the crystal plane (r) due to the etching anisotropy of the wafer material generated between the adjacent vibration elements. Residue) and the vibration element can be separated. When (W / t ² ) is smaller than 0.029, the interval is narrowed, so that the crystal plane (r-plane) generated from one outer edge is connected to the other outer edge, and the etching rate is remarkably slowed. Even in the second etching step, it cannot penetrate, and the vibration element cannot be separated. Further, when (W / t ² ) is larger than 0.033, the interval is widened. Therefore, before the crystal plane (r-plane) generated from one outer edge is connected to the other outer edge, in the second etching step, Although it can penetrate and the vibration element can be easily separated, the number of vibration elements is reduced, so that the cost cannot be reduced.

  Application Example 3 In the wafer manufacturing method according to the application example described above, the wafer is a crystal axis of quartz, an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis. The X-axis of the Cartesian coordinate system comprising the rotation axis, the Z-axis tilted so that the + Z side rotates in the −Y direction of the Y-axis is the Z′-axis, and the Y-axis is the Z-axis A crystal substrate in which an axis inclined so that the + Y side rotates in the + Z direction is a Y ′ axis, a surface including the X axis and the Z ′ axis is a main surface, and a direction along the Y ′ axis is a thickness. Preferably there is.

  According to this application example, it is possible to manufacture a vibration element suitable for downsizing and higher frequency and having excellent frequency temperature characteristics.

Application Example 4 A wafer according to this application example is integrated with a first region including a vibration region that vibrates due to thickness shear vibration, and an outer edge of the first region, and is thicker than the first region. The outer edge of the first region includes one first outer edge perpendicular to the vibration direction of the thickness-shear vibration, the other first outer edge, and one second outer edge along the vibration direction. And the other second outer edge, wherein the one first outer edge is spaced apart from the other first outer edge in the vibration direction, and the one second outer edge is separated from the other second outer edge and the vibration direction. And the second region has a first thick part connected to the one first outer edge, and a second thick part connected to the one second outer edge, and A vibration element including the first thick part and the third thick part connected to the second thick part is provided in the vibration direction. A plurality of wafers arranged along the intersecting direction, and parallel to the one second outer edge side opposite to the one second outer edge side of the second thick part of the first vibration element. The length of the gap between the outer edge and the third thick part and the other second outer edge and the first thick part of the first region of the second vibrating element arranged next to each other is W, When the thickness is t, the relationship 0.029 <(W / t ² ) <0.033 is satisfied.

According to this application example, since (W / t ² ) satisfies the relationship of 0.029 <(W / t ² ) <0.033, the crystal plane generated from one outer edge in the adjacent vibration element Can reduce the singulation failure due to being connected to the other outer edge, increase the number of wafers taken from the wafer, and obtain a low-cost vibration element.

  Application Example 5 In the wafer according to the application example described above, the wafer includes an X axis as an electrical axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, which are crystal axes of quartz. In the orthogonal coordinate system, the X axis is the rotation axis, the Z axis is tilted so that the + Z side rotates in the −Y direction of the Y axis, the Z ′ axis, and the Y axis is the + Z direction of the Z axis. A quartz substrate having an axis inclined so that the + Y side rotates as a Y ′ axis, a surface including the X axis and the Z ′ axis as a main surface, and a thickness along a direction along the Y ′ axis. preferable.

  According to this application example, it is possible to obtain a vibration element suitable for downsizing and higher frequency and having excellent frequency temperature characteristics.

1 is a schematic plan view of a wafer on which a vibration element according to an embodiment of the present invention is formed. The figure explaining the relationship between a crystal substrate and the crystal axis of a crystal. The schematic plan view of the wafer which expanded the A section in FIG. The schematic sectional drawing of the BB line in FIG. FIG. 4 is a schematic sectional view taken along line CC in FIG. 3. The figure which shows the relationship between the length W of a space | interval, and the quality of a vibration element division | segmentation. The process figure which shows the manufacturing method of the wafer which concerns on one Embodiment of this invention. (A)-(f) The schematic sectional drawing in the DD line | wire in FIG. 3 for every main process shown in FIG. (G)-(l) The schematic sectional drawing in the DD line | wire in FIG. 3 for every main process shown in FIG. 1 is a schematic plan view of a mask according to an embodiment of the present invention. The schematic plan view of the mask which forms the external shape of a vibration element.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure shown below, the size and ratio of each component may be described differently from the actual component in order to make each component large enough to be recognized on the drawing. is there.

<Wafer>
As an example of a wafer according to an embodiment of the present invention, a quartz substrate on which a vibration element 12 having an inverted mesa structure is formed is described, and a schematic configuration thereof will be described with reference to FIGS. In the following description of the schematic configuration of the crystal substrate 10 and the vibration element 12, for convenience of explanation, the X axis, the Y ′ axis, and the Z ′ axis are illustrated as three axes orthogonal to each other. The tip side of the arrow is “+ side” and the base side is “− side”. A direction parallel to the X axis is referred to as an “X axis direction”, a direction parallel to the Y ′ axis is referred to as a “Y ′ axis direction”, and a direction parallel to the Z ′ axis is referred to as a “Z ′ axis direction”. .
FIG. 1 is a schematic plan view of a wafer on which a vibration element according to an embodiment of the present invention is formed. FIG. 2 is a diagram for explaining the relationship between the AT-cut quartz substrate and the crystal axis of quartz. FIG. 3 is a schematic plan view of the wafer in which part A in FIG. 1 is enlarged. 4 is a schematic cross-sectional view taken along line BB in FIG. FIG. 5 is a schematic cross-sectional view taken along the line CC in FIG.

  The quartz crystal substrate 10 as a wafer has a plate shape, and is formed by connecting a plurality of vibration elements 12 to a frame portion 16 as a frame and an outer peripheral frame portion 18 via a connecting portion 14 as shown in FIG. Yes. The vibration element 12 formed on the quartz substrate 10 includes a first region 20 and a second region 22 that is thicker than the first region 20, and the second region 22 and the connecting portion 14 are It is connected. In addition, the plurality of vibration elements 12 are arranged in a direction (Z′-axis direction) intersecting the direction (X-axis direction) in which the connecting portion 14 is connected, and are arranged at intervals of the length W. Note that the vibration elements 12 on both ends arranged side by side are arranged at an interval of the outer peripheral frame portion 18 and the length W. Further, when the vibration element 12 is separated into pieces, the vibration element 12 is separated into pieces by being broken at the connecting portion 14.

  As shown in FIG. 2, the quartz substrate 10 has an orthogonal coordinate system X composed of an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, which are crystal axes of quartz. An axis tilted so that the Z axis is rotated by a predetermined angle θ on the + Z side in the −Y direction of the Y axis is defined as a Z ′ axis with the axis as a rotation axis. Further, an axis that is tilted so that the + Y side rotates by a predetermined angle θ in the + Z direction of the Z axis is defined as a Y ′ axis. A surface including the X axis and the Z ′ axis is a main surface, and a direction along the Y ′ axis is a thickness. The quartz substrate 10 of the present embodiment is a “rotated Y-cut quartz substrate” cut along a plane obtained by rotating the XZ ′ plane around the X axis by a predetermined angle θ, for example, θ = 35 ° 15 ′ only. The substrate cut out along the rotated plane is called “AT-cut quartz substrate”. By using such a quartz substrate 10, it is possible to obtain the vibration element 12 having excellent temperature characteristics. The main vibration of the quartz substrate 10 is thickness shear vibration, and vibrates in the X-axis direction.

Next, the vibration element 12 provided on the quartz substrate 10 will be described with reference to FIGS.
The vibration element 12 includes a first region 20 including a vibration region that vibrates due to thickness shear vibration, and a second region 22 that is integrated with the outer edge of the first region 20 and is thicker than the first region 20. It is out. The outer edge of the rectangular first region 20 is perpendicular to the vibration direction (X-axis direction), and is disposed along the vibration direction with one first outer edge 24a and the other first outer edge 24b arranged apart from each other in the vibration direction. In addition, one second outer edge 26a and the other second outer edge 26b that are spaced apart in a direction orthogonal to the vibration direction (Z′-axis direction) are included. The second region 22 includes a first thick part 28 connected to one first outer edge 24a, a second thick part 30 connected to one second outer edge 26a, and a first thick part 28. And a third thick part 32 connected to the second thick part 30.

  A plurality of vibration elements 12 arranged along the direction orthogonal to the vibration direction (Z′-axis direction) are on the opposite side of the second outer edge 26a side of the second thick portion 30 of the first vibration element 12a. The outer edge 40 formed by the outer edge parallel to the second outer edge 26a side and the third thick portion 32, and the second outer edge 26b and the first outer edge 26b of the first region 20 of the second vibrating element 12b arranged next to each other. The outer edge 42 formed by the thick portion 28 is arranged at an interval of a length W.

Next, the relationship between the distance W between the vibration elements 12 arranged along the direction orthogonal to the vibration direction (Z′-axis direction) and the thickness t of the quartz substrate 10 will be described with reference to FIG. To do.
FIG. 6 is a diagram showing a relationship between the length W of the interval and the quality of the vibration element division.
In order to find the optimum value of the distance W between the vibration elements 12 and the thickness t of the quartz substrate 10, the following experiment was performed. Using a mask for the first etching process designed with the distance W between the vibrating elements 12 in the range of 180 μm to 210 μm, the crystal substrate 10 having a thickness of 80 μm is etched by a wafer manufacturing method described later to vibrate. The element 12 was formed on the quartz substrate 10. Thereafter, an etching residue E1 (FIG. 5) generated when the vibration element 12 is broken from the frame portion 16 (outer peripheral frame portion 18) of the quartz substrate 10 or a crystal plane (r-plane) is generated due to etching anisotropy of quartz. 8 (see e)) was evaluated. In FIG. 6, the pass / fail indicates “X” when the etching residue E1 remains and the vibration element 12 cannot be folded, and “◯” indicates that the vibration element 12 can be folded without any etching residue.

From FIG. 6, when the distance W between the vibration elements 12 is 185 μm or less, the etching residue E1 remains and the vibration element 12 cannot be broken. When the distance W is 190 μm or more, there is no etching residue and the vibration element 12 It turns out that it can be broken. That is, when (W / t ² ) is greater than 0.029, no etching residue E1 remains and the vibration element 12 can be easily separated. Note that if (W / t ² ) is greater than 0.033, the interval is widened and the number of vibrating elements 12 is reduced, resulting in a problem that the cost cannot be reduced.
Therefore, if (W / t ² ) satisfies the relationship of 0.029 <(W / t ² ) <0.033, the crystal plane (due to the crystal etching anisotropy in the adjacent vibration element 12 ( It is possible to reduce the singulation failure due to the etching residue E1 generated by the generation of the (r-plane), increase the number of wafers taken, and obtain a low-cost vibration element 12.

<Wafer manufacturing method>
Next, as an example of a method for manufacturing a wafer according to an embodiment of the present invention, a method for manufacturing a quartz substrate on which a vibrating element 12 having an inverted mesa structure is formed will be described with reference to FIGS.
FIG. 7 is a process diagram showing a wafer manufacturing method according to an embodiment of the present invention. FIG. 8A to FIG. 8F are schematic cross-sectional views taken along the line DD in FIG. 3 for each main process shown in FIG. FIG. 9G to FIG. 9L are schematic cross-sectional views taken along the line DD in FIG. 3 for each main process shown in FIG. FIG. 10 is a schematic plan view of a mask according to an embodiment of the present invention. FIG. 11 is a schematic plan view of a mask that forms the outer shape of the vibration element.

  As shown in FIG. 7, the method for manufacturing the quartz substrate 10 on which the vibration element 12 having the inverted mesa structure is formed, includes a preparation process for preparing a wafer, and the vibration element 12 adjacent to the thin first region 20 serving as a vibration region. The metal layer forming step (Step 1) to the first etching step (Step 5), the metal layer peeling step (Step 6), and the outer shape of the vibration element 12 (the first region 20 and the first) 2 region 22) is formed by etching to include a metal layer forming step (Step 7) to a second etching step (Step 11), and a metal layer peeling step (Step 12).

  First, the first region 20 corresponding to the thin portion that becomes the vibration region is formed by etching, and the region corresponding to the outer shape of the adjacent vibration element 12 is simultaneously half-etched by the depth of the thin portion. I do.

<Preparation process (Step 1)>
In the preparation step (Step 1), a crystal substrate 10 as a wafer is prepared.

<Metal layer forming step (Step 2)>
Next, in the metal layer forming step (Step 2), the metal layer 50 that serves as a protective mask in the first etching step (Step 6) is formed on both main surfaces on the front and back sides of the quartz substrate 10. FIG. 8A is a schematic cross-sectional view after the metal layer 50 is formed on the quartz substrate 10. The metal layer 50 can be formed by vacuum deposition or sputtering. As a material of the metal layer 50, for example, gold (Au), platinum (Pt), or the like having high resistance to a hydrofluoric acid-based etching solution can be used. An adhesion layer (not shown) for improving the adhesion between the crystal substrate 10 and the metal layer 50 may be provided. As the adhesion layer, chromium (Cr), nickel chromium (NiCr) alloy, nickel (Ni), or the like can be used.

<Protective film application process (Step 3)>
In the protective film application step (Step 3), a resist 52 as a protective film is uniformly applied to both the front and back main surfaces of the quartz substrate 10 on which the metal layer 50 is formed using, for example, a coater device. FIG. 8B is a schematic cross-sectional view after a resist 52 is applied on the metal layer 50 of the quartz substrate 10. In the present embodiment, a positive resist 52 will be described as an example.

<Exposure process (Step 4)>
Next, in the exposure step (Step 4), exposure for forming the first region 20 of the vibration element 12 is performed. FIG. 8C is a schematic cross-sectional view in which the resist 52 is exposed through the mask 60. The resist 52 applied to the quartz substrate 10 is exposed from one main surface side of the quartz substrate 10 through a mask 60 using an exposure apparatus such as a contact aligner or a proximity liner.

Here, a mask 60 which is a photomask according to an embodiment of the present invention will be described with reference to FIG.
FIG. 10 shows the outer shape of the vibration element 12 formed by a broken line in the second etching step (Step 12) to be described later, together with the opening 62 pattern provided in the mask 60. The mask 60 has a length along the direction orthogonal to the vibration direction (Z′-axis direction) W and a length along the vibration direction (X-axis direction) equal to or greater than the length along the vibration direction of the vibration element 12. A plurality of patterns of openings 62 including a certain first opening 64 and a second opening 66 corresponding to the first region 20 of the vibration element 12 are arranged in a direction perpendicular to the vibration direction. In the present embodiment, since the positive resist 52 is used, the region where the resist 52 is left is provided with a pattern for blocking light so that light does not pass therethrough.

<Metal layer etching step (Step 5)>
Next, in the metal layer etching step (Step 5), after developing the resist 52 in the region irradiated with light, the metal layer 50 is etched, and the opening 62 pattern (see FIG. 10) shown in the mask 60 is formed on the quartz substrate 10. Formed on one of the main surfaces. FIG. 8D is a schematic sectional view after the resist 52 and the metal layer 50 are formed. The resist 52 and the metal layer 50 can protect a region that is not etched.

<First Etching Step (Step 6)>
In the first etching step (Step 6), using the patterned resist 52 and the metal layer 50 as a protective mask, the quartz substrate 10 exposed from the resist 52 and the metal layer 50 is wet-etched using a hydrofluoric acid-based etching solution. FIG. 8E is a schematic cross-sectional view after etching. The thickness-shear vibration that is the main vibration of the vibration element 12 has a frequency that is inversely proportional to the plate thickness in the vibration region, and the frequency increases as the plate thickness decreases. For example, in the case of an At-cut quartz substrate with an angle θ of 35 ° 15 ′ shown in FIG. 2, the frequency is 167 MHz when the plate thickness is 10 μm, and the frequency is 334 MHz when the plate thickness is 5 μm. . Therefore, in order to obtain a desired frequency, a portion that becomes a vibration region is etched and thinned to a desired plate thickness. Note that the vibration element 12 having a desired frequency can be obtained by measuring the etching rate in advance and performing etching for the calculated predetermined time.

During etching, as shown in FIG. 8E, an etching residue E1 is generated due to the crystal plane (r-plane) due to the crystal etching anisotropy. Etching residue E1 occurs between adjacent vibration elements 12, and when the distance between adjacent vibration elements 12 is narrow, the crystal plane (r-plane) generated from the outer edge of one vibration element 12 is connected to the outer edge of the other vibration element 12. The etching rate is significantly slowed down. Therefore, in the second etching step (Step 12) to be described later, it becomes impossible to penetrate between the adjacent vibration elements 12 into the outer shape due to the etching residue E1, and the vibration elements 12 are made to pass through the frame portion 16 and the outer peripheral frame portion of the quartz substrate 10. It cannot be separated from 18 pieces. Even if the etching residue E1 is broken and separated into pieces, a part of the etching residue E1 is connected to the outer edge of the second region 22, so that the etching residue E1 is not removed from the side wall of the package when mounted on the package thereafter. Cannot be mounted successfully. Therefore, when the thickness of the quartz substrate 10 is t, the relationship with the interval length W in the mask 60 needs to be 0.029 <(W / t ² ) <0.033.

<Metal layer peeling step (Step 7)>
In the metal layer peeling step (Step 7), the resist 52 and the metal layer 50 are peeled off after etching to a plate thickness having a desired frequency. FIG. 8F is a schematic cross-sectional view after the resist 52 and the metal layer 50 are peeled off. As a method for removing the resist 52, a wet etching method using a resist remover, a dry etching method using ozone or plasma, or the like can be used. The metal layer 50 can be peeled by a dry etching method using a reactive gas that reacts with the material used for the metal layer 50, or a wet etching method in which the material used for the metal layer 50 is immersed in a liquid that corrodes and dissolves. The method is used.

  Next, a second etching process is performed in which a region corresponding to the outer shape of the half-etched vibration element 12 is etched to make the vibration element 12 into a single piece outer shape, and the vibration element 12 is formed on the quartz substrate 10.

<Metal layer forming step (Step 8)>
In the metal layer forming step (Step 8), the metal layer 50 serving as a protective mask in the second etching step (Step 12) is formed on both front and back main surfaces of the quartz substrate 10 obtained by etching the opening 62 pattern provided in the mask 60. To do. FIG. 9G is a schematic cross-sectional view after the metal layer 50 is formed on the quartz substrate 10. The metal layer 50 can be formed by vacuum deposition or sputtering. As in the metal layer forming step (Step 1), as the material of the metal layer 50, for example, gold (Au), platinum (Pt), or the like that is highly resistant to a hydrofluoric acid-based etching solution can be used. An adhesion layer (not shown) for improving the adhesion between the crystal substrate 10 and the metal layer 50 may be provided. As the adhesion layer, chromium (Cr), nickel chromium (NiCr) alloy, nickel (Ni), or the like can be used.

<Protective film application process (Step 9)>
In the protective film application step (Step 9), a resist 52 as a protective film is uniformly applied to both the front and back main surfaces of the quartz substrate 10 on which the metal layer 50 is formed using, for example, a coater device. FIG. 9H is a schematic cross-sectional view after a resist 52 is applied on the metal layer 50 of the quartz substrate 10. In the present embodiment, as in the resist coating process (Step 3), a positive resist 52 will be described as an example.

<Exposure process (Step 10)>
Next, in the exposure step (Step 10), exposure for forming the outer shape of the vibration element 12 is performed. FIG. 9I is a schematic cross-sectional view in which the resist 52 is exposed through the mask 70. The resist 52 applied to the quartz substrate 10 is simultaneously exposed from both main surface sides of the quartz substrate 10 through a mask 70 using a double-side exposure apparatus such as a contact aligner or a proximity liner.
Here, a mask 70 which is a photomask for forming the outer shape of the vibration element 12 will be described with reference to FIG.
In FIG. 11, a plurality of external patterns for forming the external shape of the vibration element 12 are arranged along a direction (Z′-axis direction) orthogonal to the vibration direction. In the present embodiment, since the positive resist 52 is used in the same manner as the positive resist 52 used in the resist coating step (Step 8), the region where the resist 52 is left is prevented from transmitting light. A pattern for blocking light is provided.

<Metal layer etching step (Step 11)>
Next, in the metal layer etching step (Step 11), after developing the resist 52 in the region irradiated with light, the metal layer 50 is etched to form the external pattern shown in the mask 70 on both main surfaces of the quartz substrate 10. . FIG. 9 (j) is a schematic cross-sectional view after the external pattern is formed by the resist 52 and the metal layer 50. The resist 52 and the metal layer 50 can protect a region that is not etched.

<Second Etching Step (Step 12)>
In the second etching step (Step 12), the resist 52 and the metal layer 50 whose outer shapes are patterned are used as a protective mask, and the quartz substrate 10 exposed from the resist 52 and the metal layer 50 is wet-etched using a hydrofluoric acid-based etching solution. To do. FIG. 9K is a schematic cross-sectional view after etching. Etching is performed until the outer shape of the vibration element 12 penetrates. Further, the region where the etching residue E1 has occurred also penetrates by etching from both main surface sides of the quartz substrate 10, and the vibration element 12 can be easily separated. Further, when the thickness of the quartz substrate 10 is t and the length of the interval between the adjacent vibration elements 12 is W, the relationship satisfies 0.029 <(W / t ² ) <0.033. The generation of etching residue E1 due to the crystal plane (r-plane) due to the crystal etching anisotropy can be reduced, and the vibration element 12 can be easily separated into pieces.

<Metal layer peeling step (Step 13)>
In the metal layer peeling step (Step 13), the metal layer 50 is peeled after the resist 52 is peeled off. FIG. 9L is a schematic cross-sectional view after the resist 52 and the metal layer 50 are peeled off. As a method for removing the resist 52, a wet etching method using a resist remover, a dry etching method using ozone or plasma, or the like can be used. The metal layer 50 can be peeled by a dry etching method using a reactive gas that reacts with the material used for the metal layer 50, or a wet etching method in which the material used for the metal layer 50 is immersed in a liquid that corrodes and dissolves. The method is used.

  Through the above steps, the quartz substrate 10 on which the plurality of vibration elements 12 are formed is obtained. After that, after forming electrodes by photolithography technique or the like, the vibrating element 12 is completed by separating from the frame portion 16 and the outer peripheral frame portion 18 of the quartz substrate 10.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Quartz substrate as a wafer, 12 ... Vibration element, 14 ... Connection part, 16 ... Frame part as a frame, 18 ... Outer frame part as a frame, 20 ... 1st area | region, 22 ... 2nd area | region, 24a ... First outer edge, 24b ... the other first outer edge, 26a ... one second outer edge, 26b ... the other second outer edge, 28 ... the first thick part, 30 ... the second thick part, 32 ... the third thickness Meat part 40 ... outer edge 42 ... outer edge 50 ... metal layer 52 ... resist as protective film 60 ... mask 62 ... opening part 64 ... first opening 66 ... second opening 70 ... mask , E1 ... Etching residue, W ... Length of interval.

Claims (5)

A plurality of vibration elements including a thin part and a thick part that is integrated with the outer edge except for a part of the outer edge of the thin part and is thicker than the thin part are connected to the frame. A wafer manufacturing method comprising:
Etching a wafer to form a region corresponding to the thin-walled portion, and simultaneously half-etching the region corresponding to the outer shape of the vibration element by the depth of the thin-walled portion; and
Etching a region corresponding to the half-etched outer shape to form the outer shape of the piece of the vibration element; and
A method for producing a wafer, comprising: A first region including a vibration region that vibrates by thickness shear vibration;
A second region that is integrated with an outer edge of the first region and is thicker than the first region;
Including
The outer edge of the first region is
One first outer edge orthogonal to the vibration direction of the thickness-shear vibration and the other first outer edge;
One second outer edge and the other second outer edge along the vibration direction;
Including
The one first outer edge is separated from the other first outer edge in the vibration direction,
The one second outer edge is separated from the other second outer edge in a direction perpendicular to the vibration direction,
The second region is
A first thick portion connected to the first outer edge;
A second thick portion connected to the one second outer edge;
A vibration element including the first thick part and the third thick part connected to the second thick part,
A plurality are arranged along a direction orthogonal to the vibration direction,
An outer edge parallel to the one second outer edge side opposite to the one second outer edge side of the second thick part of the first vibrating element and a third thick part are arranged next to each other. A method of manufacturing a wafer separated from the other second outer edge and the first thick part of the first region of the vibration element of 2 by an interval of a length W,
A preparation process for preparing a wafer;
A protective film application step of applying a protective film on the surface of the wafer;
A first opening having a length along a direction orthogonal to the vibration direction W and a length along the vibration direction equal to or greater than a length along the vibration direction of the vibration element; and An exposure step of exposing the protective film using a mask in which a plurality of openings including the corresponding second openings are arranged along a direction orthogonal to the vibration direction,
When the thickness of the wafer is t,
0.029 <(W / t ² ) <0.033
A wafer manufacturing method characterized by satisfying the relationship: In the manufacturing method of the wafer according to claim 2,
The wafer is
A crystal axis of quartz, an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis, the X-axis of a Cartesian coordinate system as a rotation axis, and the Z-axis as the rotation axis The axis tilted so that the + Z side rotates in the −Y direction of the Y axis is defined as the Z ′ axis, the axis tilted so that the + Y side rotates in the + Z direction of the Z axis is defined as the Y ′ axis, and the X A method for producing a wafer, comprising: a quartz substrate having a surface including an axis and the Z ′ axis as a main surface and a thickness along a direction along the Y ′ axis. A first region including a vibration region that vibrates by thickness shear vibration;
A second region that is integrated with an outer edge of the first region and is thicker than the first region;
Including
The outer edge of the first region is
One first outer edge orthogonal to the vibration direction of the thickness-shear vibration and the other first outer edge;
One second outer edge and the other second outer edge along the vibration direction;
Including
The one first outer edge is separated from the other first outer edge in the vibration direction,
The one second outer edge is separated from the other second outer edge in a direction perpendicular to the vibration direction,
The second region is
A first thick portion connected to the first outer edge;
A second thick portion connected to the one second outer edge;
A vibration element including the first thick part and the third thick part connected to the second thick part,
A plurality of wafers arranged in a direction perpendicular to the vibration direction,
The outer edge parallel to the one second outer edge side opposite to the one second outer edge side of the second thick part of the first vibration element and the third thick part are arranged next to each other. The length of the interval between the other second outer edge and the first thick part of the first region of the two vibration elements is W,
The thickness of the wafer is t,
When
0.029 <(W / t ² ) <0.033
A wafer characterized by satisfying the above relationship. The wafer according to claim 4, wherein
The wafer is
A crystal axis of quartz, an X-axis as an electric axis, a Y-axis as a mechanical axis, and a Z-axis as an optical axis, the X-axis of a Cartesian coordinate system as a rotation axis, and the Z-axis as the rotation axis The axis tilted so that the + Z side rotates in the −Y direction of the Y axis is defined as the Z ′ axis, the axis tilted so that the + Y side rotates in the + Z direction of the Z axis is defined as the Y ′ axis, and the X A wafer comprising a crystal substrate having a surface including an axis and the Z ′ axis as a main surface and a thickness along a direction along the Y ′ axis.

Images