JP2022130274A - Method for manufacturing vibration element - Google Patents

Abstract

To provide a method for manufacturing a vibration element that can prevent a variation in depths of grooves.SOLUTION: A method for manufacturing a vibration element includes: a first protective film forming step of forming a first protective film on a first surface of a crystal substrate; a first dry etching step of performing dry etching on the crystal substrate from the first surface side with the first protective film therebetween to form a first groove and contours of a first vibration arm and a second vibration arm in the first surface; a second protective film forming step of forming a second protective film on a second surface of the crystal substrate; and a second dry etching step of performing dry etching on the crystal substrate from the second surface side with the second protective film therebetween to form a second groove and the contours of the first vibration arm and the second vibration arm in the second surface. When the depth of the first and second grooves formed in the first and second dry etching steps is Wa, and the depth of the contours formed in the first and second dry etching steps is Aa, in at least one of the first and second dry etching steps, Wa/Aa<1 is satisfied.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for manufacturing a vibrating element.

Patent Document 1 describes a method for manufacturing a vibrating element in which a vibrating element having a pair of vibrating arms with grooves is formed by dry etching. In this manufacturing method, by narrowing the width of the groove with respect to the width between the pair of vibrating arms, the microloading effect is used to increase the etching depth of the groove with respect to the etching depth between the pair of vibrating arms. It is made shallow, and the groove and outer shape of the vibrating element are collectively formed.

JP 2007-013382 A

However, in the manufacturing method of the vibrating element of Patent Document 1, if the dry etching time varies, the depth of the groove varies, which causes the vibration characteristics of the vibrating element to vary.

A method for manufacturing a vibrating element of the present invention comprises: a base;
a first vibrating arm and a second vibrating arm extending from the base along a first direction and arranged along a second direction intersecting the first direction;
The first vibrating arm and the second vibrating arm are respectively arranged side by side in a third direction that intersects the first direction and the second direction, and have a front-to-back relationship with a first surface and a second surface; A method for manufacturing a vibrating element having a bottomed first groove opening on a first surface and a bottomed second groove opening on the second surface,
a preparation step of preparing a crystal substrate having the first surface and the second surface;
A first groove forming region in which the first groove is formed, a first vibrating arm forming region in which the first vibrating arm is formed, and the second vibrating arm are formed on the first surface of the crystal substrate. a first protective film forming step of forming the first protective film except for the arm region located between the second vibrating arm forming regions;
The crystal substrate is dry-etched from the first surface side through the first protective film to form the first groove and the outlines of the first and second vibrating arms on the first surface. 1 dry etching step;
a second protective film forming step of forming a second protective film on the second surface of the quartz substrate except for the second groove forming region where the second groove is formed and the inter-arm region;
dry-etching the crystal substrate from the second surface side through the second protective film to form the second groove and outlines of the first vibrating arm and the second vibrating arm on the second surface; 2 a dry etching step;
Let Wa be the depth of the first groove formed in the first dry etching step and the depth of the second groove formed in the second dry etching step, respectively;
When the depth of the outer shape formed in the first dry etching step and the depth of the outer shape formed in the second dry etching step are Aa,
At least one of the first dry etching step and the second dry etching step satisfies Wa/Aa<1.

1 is a plan view showing a vibrating element according to a preferred embodiment of the present invention; FIG. 2 is a cross-sectional view taken along line A1-A1 in FIG. 1; FIG. 1. It is a figure which shows the manufacturing process of the vibration element of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 1. It is sectional drawing for demonstrating the manufacturing method of FIG. 5 is a graph showing the relationship between W/A and Wa/Aa with different etching times. 5 is a graph showing the relationship between W/A and Wa/Aa when different reaction gases are used; 4 is a graph showing the relationship between Wa/Aa and CI value. FIG. 11 is a plan view showing a modification of the vibrating element; FIG. 15 is a cross-sectional view taken along line A2-A2 in FIG. 14; FIG. 11 is a plan view showing a modification of the vibrating element; 17 is a cross-sectional view taken along line A3-A3 in FIG. 16; FIG. FIG. 11 is a plan view showing a modification of the vibrating element; FIG. 19 is a cross-sectional view taken along line A4-A4 in FIG. 18; FIG. 19 is a cross-sectional view taken along line A5-A5 in FIG. 18; FIG. 11 is a plan view showing a modification of the vibrating element; FIG. 22 is a cross-sectional view taken along line A6-A6 in FIG. 21; FIG. 22 is a sectional view taken along line A7-A7 in FIG. 21;

Hereinafter, a method for manufacturing a vibrating element of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a plan view showing a vibrating element according to a preferred embodiment of the invention. FIG. 2 is a cross-sectional view taken along line A1-A1 in FIG. 3A and 3B are diagrams showing a manufacturing process of the vibrating element of FIG. 1. FIG. 4 to 10 are cross-sectional views for explaining the manufacturing method of FIG. 1, respectively. FIG. 11 is a graph showing the relationship between W/A and Wa/Aa for different etching times. FIG. 12 is a graph showing the relationship between W/A and Wa/Aa when different reaction gases are used. FIG. 13 is a graph showing the relationship between Wa/Aa and CI value. FIG. 14 is a plan view showing a modification of the vibrating element. 15 is a cross-sectional view taken along the line A2-A2 in FIG. 14. FIG. FIG. 16 is a plan view showing a modification of the vibrating element. 17 is a cross-sectional view taken along the line A3-A3 in FIG. 16. FIG. FIG. 18 is a plan view showing a modification of the vibrating element. 19 is a cross-sectional view taken along the line A4-A4 in FIG. 18. FIG. 20 is a cross-sectional view taken along the line A5-A5 in FIG. 18. FIG. FIG. 21 is a plan view showing a modification of the vibrating element. 22 is a cross-sectional view taken along line A6-A6 in FIG. 21. FIG. 23 is a cross-sectional view taken along line A7-A7 in FIG. 21. FIG.

For convenience of explanation, three axes orthogonal to each other, the X-axis, the Y-axis and the Z-axis, are shown in each figure except FIG. 3 and FIGS. The direction along the X-axis is also called the X-axis direction (second direction), the direction along the Y-axis is also called the Y-axis direction (first direction), and the direction along the Z-axis is also called the Z-axis direction (third direction). Also say. Also, the arrow side of each axis is also called the plus side, and the opposite side is also called the minus side. Also, the positive side in the Z-axis direction is also called "upper", and the negative side is also called "lower". A plan view from the Z-axis direction is also simply referred to as a “plan view”. Also, the X-axis, Y-axis and Z-axis correspond to the crystal axes of quartz, as will be described later.

Prior to explaining the manufacturing method of the vibration element 1, the configuration of the vibration element 1 will be explained based on FIGS. 1 and 2. FIG. The vibrating element 1 is a tuning-fork type vibrating element, and has a vibrating substrate 2 and an electrode 3 formed on the surface of the vibrating substrate 2 .

The vibrating substrate 2 is formed by patterning a Z-cut crystal substrate (Z-cut crystal plate) into a desired shape, and has an extension in the XY plane defined by the X-axis and Y-axis, which are the crystal axes of crystal. and has a thickness in the Z-axis 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.

The vibrating substrate 2 has a plate-like shape, and has a first surface 2A and a second surface 2B arranged side by side in the Z-axis direction in a front-to-back relationship. Further, the vibration substrate 2 has a base portion 21, and a first vibrating arm 22 and a second vibrating arm 23 extending from the base portion 21 along the Y-axis direction and arranged along the X-axis direction.

The first vibrating arm 22 has a bottomed first groove 221 opening on the first surface 2A and a bottomed second groove 222 opening on the second surface 2B. Similarly, the second vibrating arm 23 has a bottomed first groove 231 opening on the first surface 2A and a bottomed second groove 232 opening on the second surface 2B. Each of these grooves 221, 222, 231, 232 extends along the Y-axis direction. Therefore, the first and second vibrating arms 22 and 23 each have a substantially H-shaped cross-sectional shape. As a result, the thermoelastic loss is reduced, and the vibrating element 1 has excellent vibration characteristics.

The electrode 3 has a signal electrode 31 and a ground electrode 32 . The signal electrodes 31 are arranged on the first surface 2A and the second surface 2B of the first vibrating arm 22 and both side surfaces of the second vibrating arm 23 . On the other hand, the ground electrodes 32 are arranged on both side surfaces of the first vibrating arm 22 and 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 while the ground electrode 32 is grounded, as indicated by the arrows in FIG. Bending vibration in the direction.

The vibration element 1 has been briefly described above. Next, a method for manufacturing the vibrating element 1 will be described. As shown in FIG. 3, the method of manufacturing the vibrating element 1 comprises a preparation step S1 of preparing a quartz substrate 20 as a base material of the vibrating substrate 2, and forming a first protective film 5 on the first surface 2A of the quartz substrate 20. a first protective film forming step S2 for dry-etching the crystal substrate 20 from the first surface 2A side through the first protective film 5; A second protective film forming step S4 for forming the protective film 6, and a second dry etching step S5 for dry-etching the crystal substrate 20 from the second surface 2B side through the second protective film 6. and an electrode forming step S6 of forming the electrodes 3 on the surface of the vibrating substrate 2 . Each of these steps will be described below in order.

<<Preparation step S1>>
As shown in FIG. 4, a crystal substrate 20, which is a base material of the vibration substrate 2, is prepared. The crystal substrate 20 is adjusted to a desired thickness by CMP (Chemical Mechanical Polishing) or the like, and has a sufficiently smooth first surface 2A and second surface 2B. A plurality of vibrating elements 1 are collectively formed from the crystal substrate 20 .

<<First protective film forming step S2>>
As shown in FIG. 5, metal films M1 and M2 are formed on the first surface 2A and the second surface 2B of the crystal substrate 20. As shown in FIG. Next, a first resist film R1 is formed on the metal film M1, and the formed first resist film R1 is patterned. Next, a first protective film 5 is formed in the opening of the first resist film R1, and then the first resist film R1 is removed. As a result, it becomes as shown in FIG. The first protective film 5 is not particularly limited as long as it has etching resistance, but various metal masks such as a nickel mask can be used.

The first protective film 5 has openings 51, 52 and 53 in portions of the crystal substrate 20 to be removed. Of these, the opening 51 overlaps with the first groove forming region Q1 in which the first grooves 221 and 231 are formed. The opening 52 overlaps the arm-to-arm region Q4 positioned between the first vibrating arm forming region Q2 where the first vibrating arm 22 is formed and the second vibrating arm forming region Q3 where the second vibrating arm 23 is formed. The opening 53 overlaps with the inter-element region Q5 located between the adjacent vibration substrates 2 . That is, the first protective film 5 is formed except for the groove forming region Q1, the inter-arm region Q4, and the inter-element region Q5.

<<First dry etching step S3>>
As shown in FIG. 7, the crystal substrate 20 is dry-etched from the first surface 2A side through the first protective film 5 to simultaneously form the first grooves 221 and 231 and the outline of the vibration substrate 2 on the first surface 2A. do. Note that "simultaneously formed" means that both are collectively formed in one step. More specifically, this step is reactive ion etching and is performed using an RIE (reactive ion etching) apparatus. The reaction gas introduced into the RIE apparatus is not particularly limited, but for example, _SF6 , _CF4 , _C2F4 , _C2F6 , _{C3F6 , C4F8 , etc. can} be used. can.

This process ends when the first grooves 221 and 231 reach desired depths. Here, in dry etching, a "microloading effect" is known in which the etching rate decreases as the pattern density of the first protective film 5 increases. In the present embodiment, when the width W of the first grooves 221 and 231 in the X-axis direction is compared with the width A of the inter-arm region Q4 in the X-axis direction, W<A. Further, comparing the width W and the width B of the inter-element region Q5 in the X-axis direction, W<B. Therefore, due to the microloading effect, the etching rate of the first groove forming region Q1 becomes lower than the etching rate of the inter-arm region Q4 and the inter-element region Q5. Therefore, the depth Wa of the first grooves 221 and 231 is shallower than the outer depths Aa and Ba of the vibrating substrate 2 at the end of this step. That is, Wa<Aa (Wa/Aa<1) and Wa<Ba (Wa/Ba<1). Also, the depths Aa and Ba are each more than half the thickness of the crystal substrate 20 . That is, if the thickness of the crystal substrate 20 is Ta, then Aa≧0.5Ta and Ba≧0.5Ta. The depth Wa, the depth Aa and the depth Ba are defined as the depth of the deepest part in the regions of width W, width A and width B, respectively.

After completing this step, the first protective film 5 and the metal film M1 are removed, and the back surface of the crystal substrate 20 is processed.

<<Second protective film forming step S4>>
As shown in FIG. 8, a second protective film 6 is formed on the metal film M2. The method for forming the second protective film 6 is the same as the method for forming the first protective film 5 described above. The second protective film 6 has openings 61, 62, 63 in portions of the crystal substrate 20 to be removed. Among these, the opening 61 overlaps with the second groove forming region Q6 in which the second grooves 222 and 232 are formed. The opening 62 overlaps the inter-arm region Q4. The opening 63 overlaps with the inter-element region Q5.

<<Second dry etching step S5>>
As shown in FIG. 9, the crystal substrate 20 is dry-etched from the second surface 2B side through the second protective film 6 to simultaneously form the second grooves 222 and 232 and the outline of the vibration substrate 2 on the second surface 2B. do. This step is performed in the same manner as the first dry etching step S3.

This process ends when the second grooves 222 and 232 reach desired depths. In the present embodiment, when comparing the width W of the second grooves 222 and 232 in the X-axis direction with the width A of the inter-arm region Q4 in the X-axis direction, W<A. Further, comparing the width W and the width B of the inter-element region Q5 in the X-axis direction, W<B. Therefore, due to the microloading effect, the etching rate of the second groove forming region Q6 is lower than the etching rate of the inter-arm region Q4 and the inter-element region Q5. Therefore, the depth Wa of the second grooves 222 and 232 is shallower than the depths Aa and Ba of the outer shape of the vibration substrate 2 . That is, Wa<Aa (Wa/Aa<1) and Wa<Ba (Wa/Ba<1). Also, the depths Aa and Ba are each more than half the thickness of the crystal substrate 20 . That is, Aa≧0.5Ta and Ba≧0.5Ta. Therefore, the inter-arm region Q4 and the inter-element region Q5 respectively penetrate.

As shown in FIG. 10, after this step is finished, the second protective film 6 and the metal film M2 are removed. As described above, a plurality of vibration substrates 2 are collectively formed from the crystal substrate 20 .

<<Electrode forming step S6>>
A metal film is formed on the surface of the vibration substrate 2, and the electrode 3 is formed by patterning the metal film.

As described above, the vibrating element 1 is obtained. As described above, dry etching enables processing without being affected by crystal planes of quartz crystal, and thus excellent dimensional accuracy can be achieved. Also, by collectively forming the first grooves 221, 231, the second grooves 222, 232, and the outer shape of the vibration substrate 2, the manufacturing process of the vibration element 1 can be reduced and the cost of the vibration element 1 can be reduced. be able to. Further, positional deviation of the first grooves 221, 231 and the second grooves 222, 232 with respect to the outer shape is prevented, and the formation accuracy of the vibration substrate 2 is improved.

The method for manufacturing the vibrating element 1 has been described above. Next, the conditions for more reliably expressing the microloading effect will be described. FIG. 11 shows the relationship between W/A and Wa/Aa when the etching time is varied. As can be seen from the figure, the microloading effect is remarkably manifested in the region of W/A≦40% at each time.

Also, the microloading effect changes depending on the reactive gas species used in dry etching. FIG. 12 shows the relationship between W/A and Wa/Aa when three different general reaction gases are used.

For example, if a fluorine-based gas containing a large amount of carbon such as C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₆ or C ₄ F ₈ is used as the reaction gas, a thick side wall protective film can be obtained, and gas type G3 is used. The slope becomes smaller like . Therefore, it becomes easy to increase Wa/Aa with a shape in which the width A is smaller than the width W, and the vibrating element 1 can be miniaturized. For example, when designing the frequency and the CI value, it may be necessary to have a width W above a certain level and a depth Wa close to the depth Aa. At that time, it is necessary to reduce the width A _in order to miniaturize the vibration element 1. _In such a case, at least _one of _C2F4 , _C2F6 , _{C3F6 ,} and _C4F8 is Especially effective.

On the other hand, when a fluorine-based gas containing little or no carbon, such as SF ₆ or CF ₄ , is used alone or in combination with a fluorine-based gas containing a large amount of carbon, the side wall protective film becomes thin, and gas type G1 is used. slope increases. Therefore, it is possible to increase the width A relative to the width W while keeping the depth Wa large relative to the depth Aa. For example, at least one of SF ₆ and CF ₄ is particularly effective when it is desired to narrow the width of the first and second vibrating arms 22 and 23 and increase the width A while increasing the depth Wa.

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

As shown in FIG. 12, if y is in the region P between the formulas (1) and (3), that is, if y satisfies the following formulas (4) and (5), a general reaction gas can be used to more reliably develop the microloading effect. Therefore, manufacturing of the vibrating element 1 becomes easy, and the manufacturing cost can be reduced.

Note that if y does not satisfy the expression (4), the change in the depth Wa increases with respect to the change in the width W, and the depth Wa may vary. It can be suppressed when y satisfies the formula (4). Moreover, when y does not satisfy the formula (5), it becomes difficult to increase y in a region where x is large, and the depth Wa becomes shallow. Alternatively, in order to increase the depth Wa, it is necessary to approach W=A, which is likely to cause shape restrictions. It can be suppressed when y satisfies the formula (5).

Here, for example, when the width W and the depth Wa are constant, if the gas type G2 is selected, the width A can be made smaller than the gas type G1, and the size of the vibration element 1 can be reduced. . When the gas type G3 is selected, the width A can be further reduced compared to the gas type G2, and the size of the vibration element 1 can be further reduced. In this way, from the viewpoint of miniaturization, it is preferable that y be in the region PP between the formulas (2) and (3) even in the region P. That is, y preferably satisfies the following formula (6) and the above formula (5).

FIG. 13 shows the effect of improving the CI value of the vibrating element 1 when the first grooves 221, 231 and the second grooves 222, 232 are formed. From the figure, it is preferable to satisfy Wa/Aa≧0.2. Note that, in this embodiment, Wa/Aa<1 in order to utilize the microloading effect. Thereby, the CI value can be reduced to 30% or less compared to the case where the first grooves 221 and 231 and the second grooves 222 and 232 are not formed. Therefore, the vibrating element 1 having excellent vibration characteristics can be manufactured. Furthermore, it is preferable that Wa/Aa≧0.4, whereby the CI value can be reduced to 10% or less compared to the case where the first grooves 221, 231 and the second grooves 222, 232 are not formed. .

The method for manufacturing the vibrating element 1 has been described above. As described above, the method for manufacturing the vibrating element 1 includes the base 21 and the X-axis direction extending from the base 21 along the Y-axis direction, which is the first direction, and intersecting the Y-axis direction, which is the second direction. The first vibrating arm 22 and the second vibrating arm 23 are arranged side by side in the Z-axis direction intersecting the Y-axis direction and the X-axis direction, respectively. , a first surface 2A and a second surface 2B that are in a front-back relationship, bottomed first grooves 221 and 231 that open to the first surface 2A, bottomed second grooves 222 that open to the second surface 2B, 232, comprising a preparatory step S1 of preparing a crystal substrate 20 having a first surface 2A and a second surface 2B; Between the first groove forming region Q1 in which 221 and 231 are formed, the first vibrating arm forming region Q2 in which the first vibrating arm 22 is formed, and the second vibrating arm forming region Q3 in which the second vibrating arm 23 is formed a first protective film forming step S2 of forming the first protective film 5 except for the region Q4 between the arms located in the region Q4; , a first dry etching step S3 for forming the first grooves 221 and 231 and the outlines of the first vibrating arms 22 and the second vibrating arms 23 on the first surface 2A; A second protective film forming step S4 of forming the second protective film 6 except for the second groove forming region Q6 where the grooves 222 and 232 are formed and the inter-arm region Q4, and through the second protective film 6 a second dry etching step S5 of dry-etching the crystal substrate 20 from the second surface 2B side to form the second grooves 222 and 232 and the outlines of the first vibrating arms 22 and the second vibrating arms 23 on the second surface 2B; ,including. Then, the depth of the first grooves 221 and 231 formed in the first dry etching step S3 and the depth of the second grooves 222 and 232 formed in the second dry etching step S5 are set to Wa respectively, and the first dry etching When the depth of the contour formed in the step S3 and the depth of the contour formed in the second dry etching step S5 are Aa, respectively, in at least one of the first dry etching step S3 and the second dry etching step S5, Wa/Aa<1 is satisfied. According to such a manufacturing method, the first grooves 221, 231 and the second grooves 222, 232 and the external shape of the vibration substrate 2 can be formed collectively. Therefore, the manufacturing process of the vibration element 1 can be reduced, and the cost of the vibration element 1 can be reduced. Further, positional deviation of the first grooves 221, 231 and the second grooves 222, 232 with respect to the outer shape is prevented, and the formation accuracy of the vibration substrate 2 is enhanced.

Further, as described above, in the method for manufacturing the vibration element 1, it is preferable to satisfy Wa/Aa≧0.2. Thereby, the CI value can be reduced to 30% or less compared to the case where the first grooves 221 and 231 and the second grooves 222 and 232 are not formed. Therefore, the vibrating element 1 having excellent vibration characteristics can be manufactured.

Further, as described above, in the method of manufacturing the vibration element 1, the width of the first grooves 221, 231 and the second grooves 222, 232 in the direction along the X-axis direction is W, and the width of the inter-arm region Q4 in the X-axis direction is W. When the width along the direction is A, W/A=x, and Wa/Aa=y, it is preferable to satisfy the above formula (4). As a result, the microloading effect can be developed more reliably using a general reaction gas. Therefore, manufacturing of the vibrating element 1 becomes easy, and the manufacturing cost can be reduced. Note that if y does not satisfy the expression (4), the change in the depth Wa increases with respect to the change in the width W, and the depth Wa may vary. It can be suppressed when y satisfies the formula (4).

Moreover, as described above, in the method for manufacturing the vibrating element 1, it is preferable to satisfy the above-described formula (5). As a result, the microloading effect can be developed more reliably using a general reaction gas. Therefore, manufacturing of the vibrating element 1 becomes easy, and the manufacturing cost can be reduced. If y does not satisfy Expression (5), it becomes difficult to increase y in regions where x is large, and the depth Wa becomes shallow. Alternatively, in order to increase the depth Wa, it is necessary to approach W=A, which is likely to cause shape restrictions. It can be suppressed when y satisfies the formula (5).

Further, as described above, in the method for manufacturing the vibration element 1, C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₆ and C ₄ are used as the reaction gases in the first dry etching step S3 and the second dry etching step S5. It is preferred to use at least one of _F8 . As a result, it becomes easy to increase Wa/Aa with a shape in which the width A is smaller than the width W, and the vibrating element 1 can be miniaturized.

Further, as described above, in the method for manufacturing the vibration element ₁ , it is preferable to use at least one of CF4 and _SF6 as the reaction gas in the first dry etching step S3 and the second dry etching step S5. This makes it possible to increase the width A relative to the width W while keeping the depth Wa large relative to the depth Aa. Therefore, for example, while increasing the depth Wa, the widths of the first and second vibrating arms 22 and 23 can be reduced and the width A can be increased.

Although the method of manufacturing a vibrating element according to the present invention has been described above based on the illustrated embodiments, the present invention is not limited to this, and the configuration of each part may be any configuration having similar functions. can be replaced. Also, other optional components may be added to the present invention. Further, each embodiment may be combined as appropriate.

For example, in the above-described embodiment, Wa/Aa<1 is satisfied in each of the first dry etching step S3 and the second dry etching step S5. It suffices if Aa<1 is satisfied.

Further, the vibrating element manufactured by the vibrating element manufacturing method of the present invention is not particularly limited, and may be, for example, a vibrating element 1A as shown in FIGS. In the vibrating element 1A, a pair of first grooves 221 are formed on the first surface 2A of the first vibrating arm 22 in the X-axis direction, and a pair of second grooves 222 are formed in the second surface 2B of the vibrating arm 22 in the X-axis direction. Similarly, a pair of first grooves 231 are formed along the X-axis direction on the first surface 2A of the second vibrating arm 23, and a pair of second grooves 232 are formed along the X-axis direction on the second surface 2B. is formed by In such a configuration, since a plurality of grooves are arranged, the width W of each groove tends to be narrow. Therefore, it is preferable to use at least one of SF ₆ and CF ₄ as the reaction gas in the first and second dry etching steps S3 and S5. As a result, each groove can be formed deep and the CI value can be lowered.

Also, the vibrating element may be a double tuning fork type vibrating element 7 as shown in FIGS. 16 and 17, illustration of electrodes is omitted. The double tuning fork 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 and second vibrating arms 72 and 73 include bottomed first grooves 721 and 731 opening on the first surface 7A, bottomed second grooves 722 and 732 opening on the second surface 7B, have

Further, for example, the vibration element may be a gyro vibration element 8 as shown in FIGS. 18 to 20. FIG. 18 to 20, illustration of electrodes is omitted. The gyro vibration element 8 includes a base 81, a pair of detection vibrating arms 82 and 83 extending from the base 81 on both sides in the Y-axis direction, and a pair of connecting arms 84 and 85 extending from the base 81 on both sides in the X-axis direction. , drive vibrating arms 86 and 87 extending from the tip of the connecting arm 84 to both sides in the Y-axis direction, and drive vibrating arms 88 and 89 extending from the tip of the connecting arm 85 to both sides in the Y-axis direction. In such a gyro vibration element 8, when the driving vibrating arms 86, 87, 88, and 89 are bendingly vibrated in the direction of the arrow SD in FIG. A bending vibration is newly excited in the direction of the arrow SS in the detection vibrating arms 82 and 83, and the angular velocity ωz is detected based on the charges output from the detection vibrating arms 82 and 83 due to the bending vibration.

Further, the detection vibrating arms 82 and 83 have bottomed first grooves 821 and 831 opening on the first surface 8A and bottomed second grooves 822 and 832 opening on the second surface 8B. In addition, the driving vibrating arms 86, 87, 88, 89 have bottomed first grooves 861, 871, 881, 891 opening on the first surface 8A and bottomed second grooves 862 opening on the second surface 8B. , 872, 882, 892 and . In such a gyro vibration element 8, for example, the detection vibration arm 82 and the drive vibration arm 86, the detection vibration arm 82 and the drive vibration arm 88, the detection vibration arm 83 and the drive vibration arm 87, the detection vibration arm 83 and the drive vibration arm A pair of vibrating arms such as 89 that are adjacent in the X-axis direction can be used as a first vibrating arm and a second vibrating arm.

In addition, in the case of the gyro vibration element 8, it is necessary to increase the area Q4 between the arms due to its structure. In such a case, the depth Wa becomes shallow in the region between the above formulas (2) and (3), which may lead to a decrease in sensitivity. Therefore, it is preferable to use the region between the above formulas (1) and (2).

Further, for example, the vibration element may be a gyro vibration element 9 as shown in FIGS. 21 to 23. FIG. The gyro vibration element 9 includes a base portion 91, a pair of drive vibrating arms 92 and 93 extending from the base portion 91 toward the Y-axis direction plus side and arranged in the X-axis direction, and a pair of drive vibrating arms 92 and 93 extending from the base portion 91 toward the Y-axis direction minus side, It has a pair of detection vibrating arms 94 and 95 aligned in the axial direction. In such a gyro vibration element 9, when an angular velocity ωy around the Y-axis acts while the driving vibrating arms 92 and 93 are bending-vibrating in the direction of the arrow SD in FIG. A bending vibration in the direction of arrow SS is newly excited at 94 and 95, and the angular velocity ωy is detected based on the charges output from the detection vibrating arms 94 and 95 by the bending vibration.

Further, the driving vibrating arms 92 and 93 have bottomed first grooves 921 and 931 opening to the first surface 9A and bottomed second grooves 922 and 932 opening to the second surface 9B. Further, the detection vibrating arms 94 and 95 have bottomed first grooves 941 and 951 opening on the first surface 9A and bottomed second grooves 942 and 952 opening on the second surface 9B. In such a gyro vibration element 9, the driving vibrating arms 92 and 93 or the detecting vibrating arms 94 and 95 are the first vibrating arm and the second vibrating arm.

Reference Signs List 1 Vibration element 1A Vibration element 2 Vibration substrate 2A First surface 2B Second surface 20 Crystal substrate 21 Base 22 First vibration arm 221 First groove 222 Second groove 23 Second vibrating arm 231 First groove 232 Second groove 3 Electrode 31 Signal electrode 32 Ground electrode 5 First protective film 51 Opening 52 ... opening, 53 ... opening, 6 ... second protective film, 61 ... opening, 62 ... opening, 63 ... opening, 7 ... double tuning fork vibration element, 7A ... first surface, 7B ... second surface, 711 ... base, 712...Base 72...First vibrating arm 721...First groove 722...Second groove 73...Second vibrating arm 731...First groove 732...Second groove 8...Gyro vibration element 8A... First surface 8B Second surface 81 Base 82 Detection vibrating arm 821 First groove 822 Second groove 83 Detection vibrating arm 831 First groove 832 Second groove 84... Connecting arm, 85... Connecting arm, 86... Drive vibrating arm, 861... First groove, 862... Second groove, 87... Drive vibrating arm, 871... First groove, 872... Second groove, 88... Drive vibration Arms 881 First groove 882 Second groove 89 Driving vibration arm 891 First groove 892 Second groove 9 Gyro vibration element 9A First surface 9B Second surface 91...Base 92...Drive vibrating arm 921...First groove 922...Second groove 93...Drive vibrating arm 931...First groove 932...Second groove 94...Detection vibrating arm 941...First Grooves 942 Second groove 95 Detection vibration arm 951 First groove 952 Second groove A Width Aa Depth B Width Ba Depth G1 Gas type G2 Gas species G3 Gas species M1 Metal film M2 Metal film P Region PP Region Q1 First groove forming region Q2 First vibrating arm forming region Q3 Second vibrating arm Formation region, Q4... Arm region, Q5... Inter-element region, Q6... Second groove formation region, R1... First resist film, S1... Preparatory step, S2... First protective film forming step, S3... First dry etching Steps, S4... Second protective film forming step, S5... Second dry etching step, S6... Electrode forming step, SD... Arrow, SS... Arrow, Ta... Thickness, W... Width, Wa... Depth, ωy... Angular velocity , ωz ... angular velocity

Claims (6)

a base;
a first vibrating arm and a second vibrating arm extending from the base along a first direction and arranged along a second direction intersecting the first direction;
The first vibrating arm and the second vibrating arm are respectively arranged side by side in a third direction that intersects the first direction and the second direction, and have a front-to-back relationship with a first surface and a second surface; A method for manufacturing a vibrating element having a bottomed first groove opening on a first surface and a bottomed second groove opening on the second surface,
a preparation step of preparing a crystal substrate having the first surface and the second surface;
A first groove forming region in which the first groove is formed, a first vibrating arm forming region in which the first vibrating arm is formed, and the second vibrating arm are formed on the first surface of the crystal substrate. a first protective film forming step of forming the first protective film except for the arm region located between the second vibrating arm forming regions;
The crystal substrate is dry-etched from the first surface side through the first protective film to form the first groove and the outlines of the first and second vibrating arms on the first surface. 1 dry etching step;
a second protective film forming step of forming a second protective film on the second surface of the quartz substrate except for the second groove forming region where the second groove is formed and the inter-arm region;
dry-etching the crystal substrate from the second surface side through the second protective film to form the second groove and outlines of the first vibrating arm and the second vibrating arm on the second surface; 2 a dry etching step;
Let Wa be the depth of the first groove formed in the first dry etching step and the depth of the second groove formed in the second dry etching step, respectively;
When the depth of the outer shape formed in the first dry etching step and the depth of the outer shape formed in the second dry etching step are Aa,
A method for manufacturing a vibrating element, wherein Wa/Aa<1 is satisfied in at least one of the first dry etching step and the second dry etching step. 2. The method for manufacturing a vibrating element according to claim 1, wherein Wa/Aa≧0.2 is satisfied. W is the width of the first groove and the second groove in the second direction,
Let A be the width of the inter-arm region in the second direction,
Let W/A=x,
3. The method for manufacturing a vibrating element according to claim 1, wherein the following formula is satisfied when Wa/Aa=y.

4. The method for manufacturing a vibrating element according to claim 3, wherein the following formula is satisfied.

5. _At least one of _C2F4 , _{C2F6 , C3F6} and _C4F8 is used as a reactive gas in said _first dry etching step and said _second dry etching step. A method for manufacturing a vibrating element according to any one of Claims 1 to 3. 5. The method of manufacturing a vibrating element according to claim ₁ , wherein at least one of CF4 and _SF6 is used as a reaction gas in said first dry etching step and said second dry etching step.

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