Method for manufacturing a vibrating element

Abstract

A manufacturing method of a vibration element. Generation of useless vibration and breakage of the vibration element are suppressed. The manufacturing method of the vibration element includes: a first dry etching process of dry etching a quartz substrate from a first surface side to form a first groove and an outer shape of a first vibration arm and a second vibration arm; a second dry etching process of dry etching the quartz substrate from a second surface side to form a second groove and the outer shape; and a wet etching process of forming an inclined surface connecting a bottom surface and an inner side surface of the groove, wherein when a depth of the first groove and the second groove is D, and a value obtained by subtracting a Z-direction length of the inclined surface from the depth is D1, D1 / D is equal to or greater than 0.80.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a vibrating element. Background Technology

[0002] Patent Document 1 discloses a method for manufacturing a vibrating element, which forms a vibrating element having a pair of vibrating arms with grooves by dry etching. In this manufacturing method, when dry etching a substrate made of piezoelectric material, the width of the groove is narrowed relative to the width between the pair of vibrating arms, and the etching depth of the groove is made shallower relative to the etching depth between the pair of vibrating arms by utilizing the micro-load effect, thereby forming the groove and the outer shape of the vibrating element.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2007-013382

[0004] However, in the manufacturing method of the vibration element in Patent Document 1, since dry etching is performed from both the front and back sides of the substrate, the positional misalignment of the resist film formed on the surface of the substrate and the resist film formed on the back side of the substrate may cause steps to form on the side of the vibration arm. When steps are formed on the side of the vibration arm, there are problems such as generating useless vibrations or causing damage such as cracks or gaps originating from the steps during impact. Summary of the Invention

[0005] In a method for manufacturing a vibrating element, the vibrating element has a first vibrating arm and a second vibrating arm extending along a first direction and arranged along a second direction intersecting the first direction. The first and second vibrating arms each have a first surface and a second surface, a first groove with a bottom opening on the first surface, a second groove with a bottom opening on the second surface, and a side surface connecting the first and second surfaces. The first and second surfaces are arranged in a forward and reverse orientation along a third direction intersecting the first and second directions. The manufacturing method includes: a preparation step of preparing a quartz substrate having the first surface and the second surface; and a first dry etching step of etching the quartz substrate from the first surface side. The substrate is subjected to dry etching to form the shape of the first groove, the first vibrating arm, and the second vibrating arm; a second dry etching process is performed to dry etch the quartz substrate from the second side to form the shape of the second groove, the first vibrating arm, and the second vibrating arm; and a wet etching process is performed to wet etch the side surfaces of the first and second vibrating arms, the first groove, and the second groove, forming an inclined surface connecting the bottom surface and the inner side surface of the groove in the first and second grooves. When the depth of the first and second grooves is D, and the value of the depth minus the length of the inclined surface in the third direction is D1, the first and second grooves satisfy D1 / D≥0.80. Attached Figure Description

[0006] Figure 1 This is a top view showing the vibrating element of Embodiment 1.

[0007] Figure 2 yes Figure 1 Sectional view along line A1-A1 in the diagram.

[0008] Figure 3 This is a diagram illustrating the manufacturing process of the vibration element according to Embodiment 1.

[0009] Figure 4 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0010] Figure 5 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0011] Figure 6 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0012] Figure 7 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0013] Figure 8 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0014] Figure 9 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0015] Figure 10 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0016] Figure 11 Is with Figure 10 The position of part E1 in the cross-sectional view is equivalent to that of the part in the cross-sectional view.

[0017] Figure 12 Is with Figure 10 The position of part E2 in the cross-sectional view is equivalent to that of the part in the cross-section.

[0018] Figure 13 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0019] Figure 14 It is a graph showing the relationship between the dry ratio and the Q value ratio.

[0020] Figure 15 It is a graph showing the relationship between the dry ratio and the Q-value ratio when the aspect ratio is changed.

[0021] Figure 16 This is a graph showing the relationship between W / A and Wa / Aa under different etching times.

[0022] Figure 17 This is a graph showing the relationship between W / A and Wa / Aa under different conditions of reactant gases.

[0023] Figure 18 It is a graph showing the relationship between Wa / Aa and CI ratio.

[0024] Figure 19 This is a diagram illustrating the manufacturing process of the vibration element according to Embodiment 2.

[0025] Figure 20 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0026] Figure 21 It is a cross-sectional view used to illustrate the manufacturing method of a vibrating element.

[0027] Figure 22 This is a top view showing a modified example of the vibrating element.

[0028] Figure 23 yes Figure 22 Sectional view along line A2-A2.

[0029] Figure 24 This is a top view showing a modified example of the vibrating element.

[0030] Figure 25 yes Figure 24 Sectional view along line A3-A3 in the diagram.

[0031] Figure 26 This is a top view showing a modified example of the vibrating element.

[0032] Figure 27 yes Figure 26 Sectional view along line A4-A4 in the diagram.

[0033] Figure 28 yes Figure 26 Sectional view along line A5-A5.

[0034] Figure 29 This is a top view showing a modified example of the vibrating element.

[0035] Figure 30 yes Figure 29 Sectional view along line A6-A6 in the diagram.

[0036] Figure 31 yes Figure 29 Sectional view along line A7-A7 in the diagram.

[0037] Label Explanation

[0038] 1. Vibrating element; 2. Vibrating substrate; 2A. First surface; 2B. Second surface; 101, 103. Side surfaces; 20. Quartz substrate; 21. Base; 22. First vibrating arm; 23. Second vibrating arm; 221, 231. First groove; 222, 232. Second groove; 3. Electrode; 31. Signal electrode; 32. Ground electrode; 5. First protective film; 51, 52, 53. Openings; 6. Second protective film; 61, 62, 63. Openings; 107. Step portion; 109. Third protective film; 111. Bottom surface; 112, 113. Inner side surfaces of grooves; 114, 115. Inclined surface; A. Width; Aa. Depth Degree; B width; Ba depth; D, D1, D2 depth; M1 metal film; Q1 first trench forming area; Q2 first vibrating arm forming area; Q3 second vibrating arm forming area; Q4 inter-arm area; Q5 inter-component area; Q6 second trench forming area; R1 first resist film; S1 preparation process; S2 first protective film forming process; S3 first dry etching process; S4 second protective film forming process; S5 second dry etching process; S6 wet etching process; S7 electrode forming process; S10 third protective film forming process; Ta thickness; W width; Wa depth. Detailed Implementation

[0039] 1. Implementation Method 1

[0040] The manufacturing method of the vibration element in Embodiment 1 will be described.

[0041] First, refer to Figure 1 and Figure 2 The structure of vibrating element 1 will be explained. Next, refer to... Figures 3 to 18 The manufacturing method of vibration element 1 is explained.

[0042] For ease of explanation, the X-axis, Y-axis, and Z-axis are shown as three intersecting axes in the figures with portions removed. In this embodiment, these three axes are orthogonal to each other. The direction along the X-axis is also called the X-direction, the direction along the Y-axis is also called the Y-direction, and the direction along the Z-axis is also called the Z-direction. The Y-direction corresponds to the first direction, the X-direction to the second direction, and the Z-direction to the third direction. The arrow side of each axis is also called the positive side, and the opposite side is also called the negative side. The positive side of the Z-direction is also called "up," and the negative side is also called "down." The view from the Z-direction is also simply referred to as "top view." Furthermore, as described later, the X-axis, Y-axis, and Z-axis correspond to the crystal axes of quartz.

[0043] like Figure 1 and Figure 2 As shown, the vibrating element 1 is a tuning fork type vibrating element, having a vibrating substrate 2 and electrodes 3 formed on the surface of the vibrating substrate 2.

[0044] The vibrating substrate 2 is formed by patterning a Z-cut quartz substrate, which is a Z-cut quartz plate, into a desired shape. It extends on the XY plane, which is defined by the X-axis and Y-axis, which are the axes of the quartz crystal, and has a thickness in the Z-direction. The X-axis is also called the electrical axis, the Y-axis is also called the mechanical axis, and the Z-axis is also called the optical axis.

[0045] The vibrating substrate 2 is plate-shaped and has a first surface 2A and a second surface 2B arranged opposite each other along the Z direction. Furthermore, the vibrating substrate 2 has a base 21 and a first vibrating arm 22 and a second vibrating arm 23 extending from the base 21 along the Y direction and arranged along the X direction.

[0046] The first vibrating arm 22 has a bottomed first groove 221 opening on the first surface 2A, a bottomed second groove 222 opening on the second surface 2B, and a side surface 101 connecting the first surface 2A and the second surface 2B. Similarly, the second vibrating arm 23 has a bottomed first groove 231 opening on the first surface 2A, a bottomed second groove 232 opening on the second surface 2B, and a side surface 103 connecting the first surface 2A and the second surface 2B. These first grooves 221, 231 and second grooves 222, 232 extend along the Y direction, and a bottom surface 111, inner side surfaces 112, 113, and inclined surfaces 114, 115 are formed on their inner surfaces. The inner side surfaces 112, 113 are opposite to each other, with the inner side surface 112 on the negative side of the X direction connected to the bottom surface 111 via the inclined surface 114, and the inner side surface 113 on the positive side of the X direction connected to the bottom surface 111 via the inclined surface 115. Thus, the first vibrating arm 22 and the second vibrating arm 23 each have a generally H-shaped cross-sectional shape. This results in a vibrating element 1 that reduces thermoelastic losses and possesses excellent vibration characteristics. Furthermore, the bottom surface 111 is the deepest part in the Z-direction from the first surface 2A or the second surface 2B, and is not necessarily a plane parallel to the XY plane. For example, the first grooves 221, 231 and the second grooves 222, 232 can also be shaped such that the inclined surface 114 intersects with the inclined surface 115; in this case, the edge connecting the inclined surface 114 and the inclined surface 115 corresponds to the bottom surface 111.

[0047] Electrode 3 has a signal electrode 31 and a ground electrode 32. The signal electrode 31 is disposed on the first surface 2A and the second surface 2B of the first vibrating arm 22 and on the side surface 103 of the second vibrating arm 23. Conversely, the ground electrode 32 is disposed on the side surface 101 of the first vibrating arm 22 and on the first surface 2A and the second surface 2B of the second vibrating arm 23. When a drive signal is applied to the signal electrode 31 with the ground electrode 32 grounded, as... Figure 1 As indicated by the arrows, the first vibrating arm 22 and the second vibrating arm 23 undergo bending vibration in the X direction by repeatedly approaching and separating.

[0048] The above provides a brief description of the vibrating element 1.

[0049] Next, the manufacturing method of the vibrating element 1 will be described. For example... Figure 3 As shown, the manufacturing method of the vibrating element 1 includes: a preparation step S1, preparing a quartz substrate 20 as the parent material for the vibrating substrate 2; a first protective film forming step S2, forming a first protective film 5 on the first surface 2A of the quartz substrate 20; a first dry etching step S3, performing dry etching on the quartz substrate 20 from the first surface 2A side through the first protective film 5; a second protective film forming step S4, forming a second protective film 6 on the second surface 2B of the quartz substrate 20; a second dry etching step S5, performing dry etching on the quartz substrate 20 from the second surface 2B side through the second protective film 6; a wet etching step S6, performing wet etching on the quartz substrate 20; and an electrode forming step S7, forming an electrode 3 on the surface of the vibrating substrate 2 obtained through the above steps.

[0050] The following sections will explain each of these processes in turn.

[0051] <<Preparation Process S1>>

[0052] like Figure 4 As shown, a quartz substrate 20 is prepared as the base material for the vibrating substrate 2. The quartz substrate 20 is trimmed to the desired thickness by chemical mechanical polishing (CMP) or the like, and has a sufficiently smooth first surface 2A and a second surface 2B. A plurality of vibrating elements 1 are formed together from the quartz substrate 20.

[0053] <<First Protective Film Forming Process S2>>

[0054] like Figure 5 As shown, a metal film M1 is formed on the first surface 2A of the quartz substrate 20, and a metal film M2 is formed on the second surface 2B. Next, a first resist film R1 is formed on the metal film M1, and the formed first resist film R1 is patterned. Then, a first protective film 5 is formed at the opening of the first resist film R1, and then the first resist film R1 is removed. Thus, a... Figure 6 That's right. As for the first protective film 5, there are no particular limitations as long as it is etch-resistant, and various metal masks such as nickel masks can be used.

[0055] The first protective film 5 has openings 51, 52, and 53 in the portion of the quartz substrate 20 to be removed. Opening 51 overlaps with the first groove forming region Q1 that forms the first grooves 221 and 231. Opening 52 overlaps with the inter-arm region Q4 located between the first vibrating arm forming region Q2 that forms the first vibrating arm 22 and the second vibrating arm forming region Q3 that forms the second vibrating arm 23. Opening 53 overlaps with the inter-element region Q5 located between adjacent vibrating substrates 2. That is, the first protective film 5 is formed in the region other than the first groove forming region Q1, the inter-arm region Q4, and the inter-element region Q5.

[0056] <<First Dry Etching Step S3>>

[0057] As shown in Figure 7 the figure, dry etching is performed on the quartz substrate 20 from the first surface 2A side with the first protective film 5 interposed therebetween, so that the first grooves 221, 231 and the outer shape of the vibrating substrate 2, that is, the outer shapes of the first vibrating arm 22 and the second vibrating arm 23 are simultaneously formed on the first surface 2A. In addition, "simultaneously formed" means that both are collectively formed in one step. More specifically, this step is reactive ion etching, which is performed using a reactive ion etching apparatus (RIE apparatus). The reaction gas introduced into the RIE apparatus is not particularly limited, and for example, SF6, CF4, C2F4, C2F6, C3F6, C4F8 and the like can be used.

[0058] This step ends when the first grooves 221, 231 reach a desired depth. Here, in dry etching, the "microloading effect" is known, in which the higher the pattern density of the first protective film 5, the lower the etching rate. In the present embodiment, when the width W of the first grooves 221, 231 in the X direction is compared with the width A of the inter-arm region Q4 in the X direction, W < A. Further, when the width W is compared with the width B of the inter-element region Q5 in the X direction, W < B. Therefore, due to the microloading effect, the etching rate of the first groove forming region Q1 is lower than the etching rates of the inter-arm region Q4 and the inter-element region Q5. Therefore, at the end of this step, the depth Wa of the first grooves 221, 231 is shallower than the depths Aa and Ba of the outer shape of the vibrating substrate 2. That is, Wa < Aa (Wa / Aa < 1), and Wa < Ba (Wa / Ba < 1). In addition, each of the depths Aa and Ba is equal to or more than half the thickness of the quartz substrate 20. That is, if the thickness of the quartz substrate 20 is Ta, then Aa ≥ 0.5Ta and Ba ≥ 0.5Ta.

[0059] After this step is completed, the first protective film 5 and the metal film M1 are removed, and the process proceeds to processing the back surface of the quartz substrate 20.

[0060] <<Second Protective Film Forming Step S4>>

[0061] As shown in Figure 8 the figure, the second protective film 6 is formed on the metal film M2. The film forming method of the second protective film 6 is the same as the film forming method of the first protective film 5 described above. The second protective film 6 has openings 61, 62, 63 in the portions of the quartz substrate 20 that should be removed. The opening 61 overlaps with the second groove forming region Q6 where the second grooves 222, 232 are to be formed. The opening 62 overlaps with the inter-arm region Q4. The opening 63 overlaps with the inter-element region Q5.

[0062] <<Second Dry Etching Step S5>>

[0063] As Figure 9 shown, dry etching is performed on the quartz substrate 20 from the second surface 2B side with the second protective film 6 interposed therebetween, so that the second grooves 222 and 232, and the outer shape of the vibrating substrate 2, that is, the outer shapes of the first vibrating arm 22 and the second vibrating arm 23, are simultaneously formed on the second surface 2B. This step is performed in the same manner as the first dry etching step S3.

[0064] This step ends at the moment when the second grooves 222, 232 reach a desired depth. In the present embodiment, the width W of the second grooves 222, 232 in the X direction is compared with the width A of the inter-arm region Q4 in the X direction, where W<A. Further, the width W is compared with the width B of the inter-element region Q5 in the X direction, where W<B. Therefore, due to the microloading effect, the etching rate of the second groove formation region Q6 is lower than the etching rates of the inter-arm region Q4 and the inter-element region Q5. Therefore, at the end of this step, the depth Wa of the second grooves 222, 232 is smaller than the depths Aa and Ba of the outer shape of the vibrating substrate 2. That is, Wa<Aa (Wa / Aa<1) and Wa<Ba (Wa / Ba<1). Further, the depths Aa and Ba are each equal to or more than half the thickness of the quartz substrate 20. That is, Aa≥0.5Ta and Ba≥0.5Ta. Therefore, the inter-arm region Q4 and the inter-element region Q5 are each penetrated. The inter-arm region Q4 and the inter-element region Q5 are each penetrated, so that the first vibrating arm 22 and the second vibrating arm 23 are formed.

[0065] As Figure 10 shown, after this step is completed, the second protective film 6 and the metal film M2 are removed.

[0066] As described above, in the first dry etching step S3, dry etching is performed on the quartz substrate 20 from the first surface 2A side, and in the second dry etching step S5, dry etching is performed on the quartz substrate 20 from the second surface 2B side, whereby the outer shape of the vibrating substrate 2 is formed. Therefore, for example, when the respective positions of the first protective film 5 and the second protective film 6 are displaced due to manufacturing variations or the like when viewed in plan from the Z direction, a step may be formed on the side surface 101 of the first vibrating arm 22 and the side surface 103 of the second vibrating arm 23 in the region 105 where both the dry etching in the first dry etching step S3 and the dry etching in the second dry etching step S5 overlap.

[0067] As Figure 11 and Figure 12As shown, for example, when the position of the second protective film 6 is offset to the negative side in the X direction relative to the first protective film 5, the shape of the vibrating substrate 2 formed in the second dry etching process S5 is offset to the negative side in the X direction relative to the shape of the vibrating substrate 2 formed in the first dry etching process S3, thereby forming a step portion 107 on the side surface 101 of the first vibrating arm 22. Additionally, for example, when the position of the second protective film 6 is offset to the positive side in the X direction relative to the first protective film 5, a step portion 107 is also formed. Furthermore, while the first vibrating arm 22 has been described as an example, when the position of the second protective film 6 is offset relative to the first protective film 5, a step portion 107 is also formed on the side surface 103 of the second vibrating arm 23.

[0068] <<Wet Etching Process S6>>

[0069] The wet etching process S6 is a process of wet etching the quartz substrate 20 by immersing it in an etching solution. The etching solution can be hydrofluoric acid or ammonium fluoride.

[0070] As described above, the first vibrating arm 22 and the second vibrating arm 23 are formed on the quartz substrate 20 through the first dry etching process S3 and the second dry etching process S5. That is, this process is a wet etching process for the first vibrating arm 22 and the second vibrating arm 23. Specifically, the side surfaces 101 and 103 of the first vibrating arm 22 and the second vibrating arm 23, as well as the first grooves 221 and 231 and the second grooves 222 and 232, are wet etched. In this process, by wet etching the side surfaces 101 and 103 of the first vibrating arm 22 and the second vibrating arm 23, the step portion 107 formed on the side surfaces 101 and 103 can be reduced. By reducing the step portion 107, the generation of unwanted vibrations when the vibrating element 1 vibrates and the breakage of the vibrating element 1 when an impact is applied to the vibrating element 1 can be suppressed.

[0071] In addition, in this process, wet etching is performed on the first grooves 221 and 231 and the second grooves 222 and 232, such as... Figure 13 As shown, inclined surfaces 114 and 115 and a bottom surface 111 are formed on the inner surfaces of the first grooves 221 and 231 and the second grooves 222 and 232.

[0072] When the depth of the groove formed by the first dry etching process S3 and the second dry etching process S5 is D1, and the depth of the groove formed by the wet etching process S6 is D2, the final groove depth D after the wet etching process S6 is the distance in the Z direction from the first surface 2A or the second surface 2B to the bottom surface 111, which is D1 + D2. Furthermore, depth D1 is equal to the aforementioned depth Wa. Additionally, depth D1 can be considered as the Z-direction distance between the boundary farther from the bottom surface 111 of the inner surface 112 and the inclined surface 114, and the boundary between the inner surface 113 and the inclined surface 115, and the first surface 2A or the second surface 2B. Furthermore, depth D2 can be considered as the Z-direction distance from the boundary farther from the bottom surface 111 to the bottom surface 111. In this embodiment, the distance in the Z direction between the boundary of the inner side surface 112 of the groove and the inclined surface 114 and the first surface 2A or the second surface 2B is the depth D1, and the distance in the Z direction from this boundary to the bottom surface 111 is the depth D2. That is, the depth D2 is the length of the inclined surface 114 in the Z direction, and the depth D1 is the value of depth D minus depth D2.

[0073] Figure 14 This is a graph showing the simulation results of the relationship between the dry etching ratio D1 / D and the Q-value ratio. Here, the dry etching ratio D1 / D is the ratio of the depth D1 of the groove formed by dry etching to the final groove depth D. The Q-value ratio is the ratio of the Q-value of the vibrating element 1 when the dry etching ratio D1 / D is 0, i.e., the Q-value when the first grooves 221 and 231 and the second grooves 222 and 232 are formed only by wet etching, normalized to 100%. Figure 14 As shown, the Q value of the vibrating element 1 changes according to the dry ratio D1 / D. Specifically, the larger the dry ratio D1 / D, the higher the Q value. Within the range where the dry ratio D1 / D is ≥ 0.80, the Q value remains approximately constant. This Q value is the same as the Q value when the dry ratio D1 / D is 1.00, i.e., when the first vibrating arm 22 and the second vibrating arm 23 are formed with an ideal shape without the step portion 107 by dry etching alone. Thus, by forming the first grooves 221 and 231 and the second grooves 222 and 232 with a dry ratio D1 / D satisfying D1 / D ≥ 0.80, the Q value can be significantly improved compared to the case where they are formed by wet etching alone.

[0074] also, Figure 15 This is a graph showing the simulation results of the relationship between the dry ratio D1 / D and the Q value ratio when the aspect ratio D / W is changed. The aspect ratio D / W is the ratio of the groove depth D to the groove width W. Figure 15As shown, even if the aspect ratio D / W changes, the Q value can be significantly improved by making the dryness ratio D1 / D ≥ 0.80. Furthermore, if the first grooves 221 and 231 and the second grooves 222 and 232 are formed with a dryness ratio D1 / D satisfying D1 / D ≥ 0.85, an even better Q value can be obtained.

[0075] In the wet etching process S6, the etching amount of the sides 101 and 103 is preferably 0.01 μm or more. This reduces the size of the step portion 107, suppressing the generation of unwanted vibrations when the vibrating element 1 vibrates and preventing damage to the vibrating element 1 when impacted. Furthermore, the etching amount of the sides 101 and 103 is the displacement of the sides 101 and 103 in the X direction, which is orthogonal to the sides 101 and 103, before and after the wet etching process S6.

[0076] Furthermore, in this process, the etching depth of sides 101 and 103 is preferably 1 μm or less. If the etching depth of sides 101 and 103 exceeds 1 μm, then various parts of the vibrating substrate 2 other than the step portion 107, such as the first surface 2A, the second surface 2B, the first grooves 221 and 231, and the second grooves 222 and 232, will be wet-etched, resulting in the external dimensions of the vibrating element 1 being different from the desired external dimensions. Therefore, the vibrating element 1 may vibrate at a frequency far deviating from the desired frequency. By setting the etching depth of sides 101 and 103 to 1 μm or less, deviation from the desired frequency can be suppressed.

[0077] Furthermore, in this process, the etching amount of sides 101 and 103 is preferably 0.5 μm or less. When the etching amount of sides 101 and 103 exceeds 0.5 μm, for example, the corners of the vibrating arms 22 and 23 connected to the first surface 2A and the second surface 2B and sides 101 and 103 are wet-etched, resulting in a complex shape of the vibrating element 1 that differs from the desired shape. Therefore, unwanted vibrations may occur when the vibrating element 1 is vibrating, and vibration characteristics such as the Q value may decrease. By setting the etching amount of sides 101 and 103 to 0.5 μm or less, the generation of unwanted vibrations can be suppressed.

[0078] Through the above processes S1 to S6, multiple vibrating substrates 2 are formed from the quartz substrate 20.

[0079] <<Electrode Formation Process S7>>

[0080] A metal film is formed on the surface of the vibrating substrate 2, and the metal film is patterned to form an electrode 3.

[0081] Through the above processes, vibration element 1 is obtained.

[0082] As described above, dry etching allows for processing without being affected by the crystal planes of the quartz, thus achieving excellent dimensional accuracy. Furthermore, by forming the first grooves 221, 231 and the second grooves 222, 232 along with the outer shape of the vibrating substrate 2, the manufacturing process of the vibrating element 1 can be reduced, and the cost of the vibrating element 1 can be lowered. Additionally, preventing positional misalignment of the first grooves 221, 231 and the second grooves 222, 232 relative to the outer shape improves the forming accuracy of the vibrating substrate 2.

[0083] Furthermore, when dry etching is performed on the quartz substrate 20 from both the first surface 2A and the second surface 2B, wet etching can reduce the step portions 107 formed on the side surfaces 101 and 103 of the first vibrating arm 22 and the second vibrating arm 23. Therefore, it is possible to suppress the generation of unwanted vibrations when the vibrating element 1 vibrates and to suppress the breakage of the vibrating element 1 when an impact is applied to the vibrating element 1.

[0084] The manufacturing method of the vibration element 1 has been described above.

[0085] Next, refer to Figure 16 and Figure 17 The conditions for more reliably revealing the effects of micro-loading are explained.

[0086] Figure 16 The figure shows the relationship between W / A and Wa / Aa for different etching times. As can be seen from the figure, a significant micro-loading effect is observed at all times in the region where W / A ≤ 40%.

[0087] In addition, the micro-load effect also varies depending on the type of reactive gas used in dry etching. Figure 17 The relationship between W / A and Wa / Aa is shown when three different common reactive gases are used.

[0088] For example, if the reactant gas is a fluorine-based gas containing a large amount of carbon, such as C2F4, C2F6, C3F6, or C4F8, a thick sidewall protective film can be obtained, and the slope becomes smaller, as with gas type G3. Therefore, it is easy to increase Wa / Aa in a shape where the width A is smaller than the width W, which allows for miniaturization of the vibrating element 1. For example, when designing the frequency and CI value, sometimes a width W of a certain value or higher and a depth Wa close to the value of the depth Aa are required. In this case, in order to miniaturize the vibrating element 1, it is necessary to reduce the width A. In this case, at least one of C2F4, C2F6, C3F6, and C4F8 is particularly effective.

[0089] On the other hand, when fluorinated gases such as SF6 and CF4, which are low in carbon or contain no carbon, are used alone or in combination with fluorinated gases that are high in carbon, the sidewall protective film becomes thinner, and the slope becomes greater, as with gas type G1. Therefore, it is possible to maintain a larger depth Wa relative to depth Aa and increase the width A relative to width W. For example, at least one of SF6 and CF4 is particularly effective when it is desired to increase the depth Wa and make the widths of the first vibrating arm 22 and the second vibrating arm 23 thinner and the width A larger.

[0090] When W / A = x and Wa / Aa = y, gas type G1 is represented by the following formula (1), gas type G2 is represented by the following formula (2), and gas type G3 is represented by the following formula (3).

[0091] y = -4.53 × 10 -6 x 4 +3.99×10 -4 x 3 -1.29×10 -3 x 2 +1.83×10 -1 x...(1)

[0092] y = -5.59 × 10 -8 x 4 +1.48×10 -5 x 3 -1.43×10 -3 x 2 +6.09×10 -2 x...(2)

[0093] y = -6.90 × 10 -10 x 4 +5.47×10 -7 x 3 -1.59×10 -4 x 2 +2.03×10 -2 x...(3)

[0094] like Figure 17 As shown, if y lies in region P between equations (1) and (3), that is, if y satisfies equations (4) and (5) below, then the micro-load effect can be more reliably manifested using a general reactive gas. Therefore, the manufacturing of the vibrating element 1 becomes easier, and its manufacturing cost can be reduced.

[0095] y≥-4.53×10 -6 x 4 +3.99×10 -4 x 3 -1.29×10 -3 x2 +1.83×10 -1 x...(4)

[0096] y≤-6.90×10 -10 x 4 +5.47×10 -7 x 3 1.59×10 -4 x 2 +2.03×10 -2 x...(5)

[0097] When y does not satisfy equation (4), the change in depth Wa relative to width W becomes larger, and the depth Wa may deviate. This can be suppressed by ensuring y satisfies equation (4). Furthermore, when y does not satisfy equation (5), it is difficult to increase y in regions where x is large, resulting in a shallower depth Wa. Alternatively, to increase the depth Wa, it is necessary to approach W = A, which can easily lead to shape constraints. This can also be suppressed by ensuring y satisfies equation (5).

[0098] Here, for example, when the width W and depth Wa are set constant, if gas type G2 is selected, the width A can be reduced compared to gas type G1, and miniaturization of the vibrating element 1 can be achieved. If gas type G3 is selected, the width A can be further reduced compared to gas type G2, and further miniaturization of the vibrating element 1 can be achieved. Thus, from the viewpoint of miniaturization, in region P, it is further preferable that y lies in region PP between equations (2) and (3). That is, it is preferable that y satisfies equation (6) and equation (5) above.

[0099] y≥-5.59×10 -8 x 4 +1.48×10 -5 x 3 -1.43×10 -3 x 2 +6.09×10 -2 x...(6)

[0100] Next, refer to Figure 18 This demonstrates the improvement effect of the CI value of the vibrating element 1 when the first groove 221, 231 and the second groove 222, 232 are formed.

[0101] Figure 18 The relationship between Wa / Aa and the CI ratio is shown. Here, the CI ratio is the ratio of the normalized CI values ​​when the first grooves 221 and 231 and the second grooves 222 and 232 are not formed, set to 1.0. Figure 18As shown, Wa / Aa ≥ 0.2 is preferred. In this embodiment, Wa / Aa < 1 in order to utilize the micro-load effect. Therefore, compared with the case where the first grooves 221, 231 and the second grooves 222, 232 are not formed, the CI value can be reduced to less than 30%. Therefore, it is possible to manufacture a vibration element 1 with excellent vibration characteristics. Moreover, Wa / Aa ≥ 0.4 is preferred, thereby reducing the CI value to less than 10% compared with the case where the first grooves 221, 231 and the second grooves 222, 232 are not formed.

[0102] The above describes the conditions for more reliably manifesting the micro-load effect in the manufacturing method of the vibrating element 1.

[0103] As described above, in the manufacturing method of the vibrating element 1, the vibrating element 1 has a first vibrating arm 22 and a second vibrating arm 23 extending along the Y direction (a first direction) and arranged along the X direction (a second direction) intersecting the Y direction. The first vibrating arm 22 and the second vibrating arm 23 each have a first surface 2A and a second surface 2B, a first groove 221 and 231 with a bottom opening on the first surface 2A, a second groove 222 and 232 with a bottom opening on the second surface 2B, and side surfaces 101 and 103 connecting the first surface 2A and the second surface 2B. The first surface 2A and the second surface 2B are arranged in a positive-negative relationship along the Z direction (a third direction) intersecting the Y and X directions. The manufacturing method includes: a preparation step S1, preparing a quartz substrate 20 having a first surface 2A and a second surface 2B; and a first dry etching step S3, dry etching the quartz substrate 20 from the first surface 2A side to form the first... The outlines of grooves 221 and 231, the first vibrating arm 22, and the second vibrating arm 23 are formed; a second dry etching process S5 is performed to dry etch the quartz substrate 20 from the second surface 2B side to form the outlines of the second grooves 222 and 232, the first vibrating arm 22, and the second vibrating arm 23; and a wet etching process S6 is performed to etch the side surfaces 101 and 103 of the first vibrating arm 22 and the second vibrating arm 23, the first grooves 221 and 231, and the second grooves 222 and 23. 2. Perform wet etching to form inclined surfaces 114 and 115 connecting the bottom surface 111 and the inner side surfaces 112 and 113 in the first trench 221, 231 and the second trench 222, 232. When the depth of the first trench 221, 231 and the second trench 222, 232 is D, and the value after subtracting the length of the inclined surface 114 in the Z direction from the depth is D1, the first trench 221, 231 and the second trench 222, 232 satisfy D1 / D≥0.80.

[0104] According to this manufacturing method, the stepped portions 107 formed on the sides 101, 103 of the first vibrating arm 22 and the second vibrating arm 23 can be reduced. This suppresses the generation of unwanted vibrations when the vibrating element 1 vibrates and prevents damage to the vibrating element 1 when impacts are applied. Furthermore, as described above, since the dry ratio D1 / D satisfies D1 / D≥0.80, the Q value can be improved.

[0105] Furthermore, as described above, in the manufacturing method of the vibrating element 1, it is preferable that the dry ratio D1 / D of the first grooves 221 and 231 and the second grooves 222 and 232 satisfies D1 / D≥0.85. This further improves the Q value.

[0106] Furthermore, as described above, in the manufacturing method of the vibrating element 1, the etching amount of the sides 101 and 103 in the wet etching process S6 is preferably 0.01 μm or more. As a result, the step portion 107 is reduced, which can suppress the generation of useless vibrations when the vibrating element 1 vibrates and the damage to the vibrating element 1 when an impact is applied to it.

[0107] Furthermore, as described above, in the manufacturing method of the vibrating element 1, the etching amount of the sides 101 and 103 in the wet etching process S6 is preferably 1 μm or less. This allows for the suppression of deviations from the desired frequency when the vibrating element 1 is vibrating.

[0108] Furthermore, as described above, in the manufacturing method of the vibrating element 1, the etching amount of the sides 101 and 103 in the wet etching process S6 is preferably 0.5 μm or less. This suppresses the generation of unwanted vibrations when the vibrating element 1 vibrates.

[0109] Furthermore, as described above, in the manufacturing method of the vibration element 1, when the depths of the first grooves 221 and 231 formed by the first dry etching process S3 and the depths of the second grooves 222 and 232 formed by the second dry etching process S5 are Wa respectively, and the depths of the outlines of the first vibration arm 22 and the second vibration arm 23 formed by the first dry etching process S3 and the depths of the outlines of the first vibration arm 22 and the second vibration arm 23 formed by the second dry etching process S5 are Aa respectively, it is preferable that Wa / Aa < 1 is satisfied in at least one of the first dry etching process S3 and the second dry etching process S5. Therefore, the first grooves 221 and 231, the second grooves 222 and 232, and the outline shape of the vibration substrate 2 can be formed simultaneously. Thus, the manufacturing process of the vibration element 1 can be reduced, and the cost of the vibration element 1 can be lowered. In addition, preventing the positional displacement of the first grooves 221 and 231 and the second grooves 222 and 232 relative to the outline shape improves the forming accuracy of the vibration substrate 2.

[0110] 2. Implementation Method 2

[0111] Reference Figures 19-21 The manufacturing method of the vibration element 1 in Embodiment 2 is described below. Furthermore, structures identical to those in Embodiment 1 are labeled with the same reference numerals, and repeated descriptions are omitted.

[0112] In Embodiment 2, a third protective film forming process S10 is provided between the second dry etching process S5 and the wet etching process S6. In the third protective film forming process S10, a third protective film 109 is formed on the first surface 2A and the second surface 2B of the quartz substrate 20. In the wet etching process S6, the first surface 2A and the second surface 2B of the quartz substrate 20 are covered by the third protective film 109. Otherwise, Embodiment 2 is the same as Embodiment 1.

[0113] like Figure 19 As shown, the manufacturing method of the vibration element 1 in Embodiment 2 includes: a preparation step S1, preparing a quartz substrate 20 as the parent material for the vibration substrate 2; a first protective film forming step S2, forming a first protective film 5 on the first surface 2A of the quartz substrate 20; a first dry etching step S3, dry etching the quartz substrate 20 from the first surface 2A side through the first protective film 5; a second protective film forming step S4, forming a second protective film 6 on the second surface 2B of the quartz substrate 20; a second dry etching step S5, dry etching the quartz substrate 20 from the second surface 2B side through the second protective film 6; a third protective film forming step S10, forming a third protective film 109 on the first surface 2A and the second surface 2B of the quartz substrate 20; a wet etching step S6, wet etching the quartz substrate 20; and an electrode forming step S7, forming an electrode 3 on the surface of the vibration substrate 2 obtained by the above steps.

[0114] The preparation process S1 to the second dry etching process S5 is the same as in Embodiment 1, so the description is omitted. The description will proceed from the third protective film formation process S10. In addition, as in Embodiment 1, after the second dry etching process S5, the second protective film 6 and the metal film M2 are removed from the quartz substrate 20.

[0115] <<Third protective film formation process S10>>

[0116] like Figure 20 As shown, a third protective film 109 is formed on the first surface 2A and the second surface 2B of the quartz substrate 20. The third protective film 109 is, for example, a metal film of chromium and gold sequentially formed from the side of the quartz substrate 20. The metal film is formed on the surface of the quartz substrate 20, for example, using sputtering or Chemical Vapor Deposition (CVD), and the metal film is patterned using photolithography and etching techniques, thereby forming the third protective film 109.

[0117] <<Wet Etching Process S6>>

[0118] In this process, the quartz substrate 20 is wet-etched by immersing it in an etching solution.

[0119] In Embodiment 2, prior to this step, a third protective film 109 is formed on the first surface 2A and the second surface 2B of the quartz substrate 20 in the third protective film formation step S10. Therefore, in this step, the first surface 2A and the second surface 2B of the quartz substrate 20 are shielded by the third protective film 109. In other words, the first surface 2A and the second surface 2B of the first vibrating arm 22 and the second vibrating arm 23 are shielded by the third protective film 109. That is, in this step, the first surface 2A and the second surface 2B of the first vibrating arm 22 and the second vibrating arm 23 are not wet-etched. This prevents the size or shape of the vibrating element 1 from becoming different from the desired size or shape. Therefore, it is possible to suppress deviations from the desired frequency of the vibrating element 1 or the generation of unwanted vibrations.

[0120] Since the third protective film 109 is not formed on the sides 101 and 103 of the first vibrating arm 22 and the second vibrating arm 23, the step portion 107 formed on the sides 101 and 103 can be reduced, similar to Embodiment 1.

[0121] like Figure 21 As shown, after this process is completed, the third protective film 109 is removed. As a result, a plurality of vibrating substrates 2 are formed together from the quartz substrate 20.

[0122] <<Electrode Formation Process S7>>

[0123] This process is performed in the same manner as in Embodiment 1. A metal film is formed on the surface of the vibrating substrate 2, and the metal film is patterned to form the electrode 3.

[0124] Through the above processes, vibration element 1 is obtained.

[0125] According to this embodiment, in addition to the effects of embodiment 1, the following effects can also be obtained.

[0126] In the wet etching process S6, the first surface 2A and the second surface 2B of the quartz substrate 20 are shielded by the third protective film 109, thereby preventing the size or shape of the vibrating element 1 from becoming different from the desired size or shape. As a result, deviations from the desired frequency of the vibrating element 1 or the generation of unwanted vibrations can be suppressed.

[0127] The manufacturing method of the vibration element of the present invention has been described above according to Embodiment 1 and Embodiment 2.

[0128] However, the present invention is not limited thereto, and the structure of each part can be replaced with any structure having the same function. Furthermore, other arbitrary components can be added to the present invention. Additionally, the various embodiments can be appropriately combined.

[0129] For example, in the above embodiment, Wa / Aa<1 is satisfied in the first dry etching step S3 and the second dry etching step S5, but it is not limited to this, as long as at least one of them satisfies Wa / Aa<1.

[0130] Furthermore, the vibrating element manufactured by the method of the present invention is not particularly limited, and for example, it can be... Figure 22 and Figure 23 The vibrating element 1A is shown. In the vibrating element 1A, a pair of first grooves 221 are formed along the X direction on the first surface 2A of the first vibrating arm 22, and a pair of second grooves 222 are formed along the X direction on the second surface 2B. Similarly, a pair of first grooves 231 are formed along the X direction on the first surface 2A of the second vibrating arm 23, and a pair of second grooves 232 are formed along the X direction on the second surface 2B. In this structure, due to the arrangement of multiple grooves, the width W of each groove can easily become thinner. Therefore, in the first dry etching step S3 and the second dry etching step S5, at least one of SF6 and CF4 is preferably used as the reactive gas. As a result, each groove can be formed more deeply, and the CI value can be reduced.

[0131] In addition, the vibrating element can also be Figure 24 and Figure 25 The double tuning fork type vibrating element 7 is shown. Additionally, in... Figure 24 and Figure 25 The electrodes are not shown in the diagram. The double tuning fork type vibrating element 7 has a pair of bases 711 and 712 and a first vibrating arm 72 and a second vibrating arm 73 connecting the bases 711 and 712. In addition, the first vibrating arm 72 and the second vibrating arm 73 have a bottomed first groove 721 and 731 that open on the first surface 7A and a bottomed second groove 722 and 732 that open on the second surface 7B, respectively.

[0132] Alternatively, for example, the vibrating element can also be Figures 26-28 The gyroscope oscillating element 8 is shown. Additionally, in... Figures 26-28 The electrodes are omitted from the diagram. The gyroscope vibration element 8 has a base 81, a pair of detection vibration arms 82 and 83 extending from the base 81 in the Y direction, a pair of connecting arms 84 and 85 extending from the base 81 in the X direction, drive vibration arms 86 and 87 extending from the front end of the connecting arm 84 in the Y direction, and drive vibration arms 88 and 89 extending from the front end of the connecting arm 85 in the Y direction. In this gyroscope vibration element 8, when the drive vibration arms 86, 87, 88, and 89 are directed towards... Figure 26When the angular velocity ωz around the Z-axis is applied under the bending vibration state in the direction of arrow SD, the bending vibration in the direction of arrow SS is re-excited by the Coriolis force on the detection vibration arms 82 and 83, and the angular velocity ωz is detected based on the charge output from the detection vibration arms 82 and 83 through the bending vibration.

[0133] Furthermore, the detection vibration arms 82 and 83 have a first groove 821 and 831 with a bottom that opens on the first surface 8A, and a second groove 822 and 832 with a bottom that opens on the second surface 8B. Similarly, the drive vibration arms 86, 87, 88, and 89 have a first groove 861, 871, 881, and 891 with a bottom that opens on the first surface 8A, and a second groove 862, 872, 882, and 892 with a bottom that opens on the second surface 8B. In this gyroscope vibration element 8, for example, a pair of vibration arms adjacent in the X direction, such as the detection vibration arm 82 and drive vibration arm 86, the detection vibration arm 82 and drive vibration arm 88, the detection vibration arm 83 and drive vibration arm 87, and the detection vibration arm 83 and drive vibration arm 89, can be designated as the first vibration arm and the second vibration arm.

[0134] Furthermore, in the case of the gyroscope vibration element 8, the inter-arm region Q4 needs to be increased structurally. In this case, the depth Wa in the region between equations (2) and (3) above becomes shallower, which may lead to a decrease in sensitivity. Therefore, it is preferable to use the region between equations (1) and (2) above.

[0135] Alternatively, for example, the vibrating element can also be Figures 29-31 The gyroscope vibration element 9 shown is a base 91, a pair of drive vibration arms 92 and 93 extending from the base 91 in the positive Y direction and arranged in the X direction, and a pair of detection vibration arms 94 and 95 extending from the base 91 in the negative Y direction and arranged in the X direction. In this gyroscope vibration element 9, when the drive vibration arms 92 and 93 are directed towards... Figure 29 When the angular velocity ωy about the Y-axis is applied under the bending vibration state in the direction of arrow SD, the bending vibration in the direction of arrow SS is re-excited by the Coriolis force on the detection vibration arms 94 and 95, and the angular velocity ωy is detected based on the charge output from the detection vibration arms 94 and 95 through the bending vibration.

[0136] Furthermore, the driving vibration arms 92 and 93 have a first groove 921 and 931 with a bottom that opens on the first surface 9A and a second groove 922 and 932 with a bottom that opens on the second surface 9B. Similarly, the detection vibration arms 94 and 95 have a first groove 941 and 951 with a bottom that opens on the first surface 9A and a second groove 942 and 952 with a bottom that opens on the second surface 9B. In this gyroscope vibration element 9, the driving vibration arms 92 and 93 or the detection vibration arms 94 and 95 serve as the first vibration arm and the second vibration arm, respectively.

Claims

1. A method for manufacturing a vibrating element, the vibrating element having a first vibrating arm and a second vibrating arm extending along a first direction and arranged along a second direction intersecting the first direction, the first vibrating arm and the second vibrating arm each having a first surface and a second surface, a first groove with a bottom opening on the first surface, a second groove with a bottom opening on the second surface, and a side surface connecting the first surface and the second surface, the first surface and the second surface being arranged in a positive-negative relationship in a third direction intersecting the first direction and the second direction. The manufacturing method includes: Preparation process: preparing a quartz substrate having the first surface and the second surface; The first dry etching process involves dry etching the quartz substrate from the first side to form the shape of the first groove, the first vibrating arm, and the second vibrating arm. The second dry etching process involves dry etching the quartz substrate from the second side, forming the second groove while simultaneously connecting the area between the first and second vibrating arms to form the shape of the first and second vibrating arms. as well as The wet etching process involves etching the sides of the first and second vibrating arms, as well as the first and second grooves, to form inclined surfaces in the first and second grooves that connect the bottom surface and the inner side surface of the groove. When the depth of the first groove and the second groove is D, and the value of the depth minus the length of the third direction of the inclined surface is D1, the first groove and the second groove satisfy D1 / D≥0.

80.

2. The method for manufacturing a vibrating element according to claim 1, wherein, The first slot and the second slot satisfy D1 / D≥0.

85.

3. The method for manufacturing a vibrating element according to claim 1 or 2, wherein, The etching depth of the side surface in the wet etching process is 0.01 μm or more.

4. The method for manufacturing a vibrating element according to claim 1 or 2, wherein, The etching depth of the side surface in the wet etching process is less than 1 μm.

5. The method for manufacturing a vibrating element according to claim 1 or 2, wherein, The etching depth of the side surface in the wet etching process is less than 0.5 μm.

6. The method for manufacturing a vibrating element according to claim 1 or 2, wherein, In the wet etching process, the first surface and the second surface are masked.

7. The method for manufacturing a vibrating element according to claim 1 or 2, wherein, When the depth of the first groove formed by the first dry etching process and the depth of the second groove formed by the second dry etching process are Wa, and the depth of the shape formed by the first dry etching process and the depth of the shape formed by the second dry etching process are Aa, Wa / Aa < 1 is satisfied in at least one of the first dry etching process and the second dry etching process.

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