JP2014187577A - Vibrator, oscillator, electronic apparatus, mobile body, and process of manufacturing the vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact vibrator having high vibration efficiency and suppressed vibration leakage.SOLUTION: A MEMS vibrator 100 includes: a substrate 1; a stationary part 23 provided on a principle plane of the substrate 1; support parts 25 extending from the stationary part 23; and a vibration body (an upper electrode 20), separated from the substrate 1 by the support parts 25, whose node part of the vibration is supported. The vibration body is a rotationally symmetric body of 2n symmetricity having 2n beams extending spokewise from the node part of the vibration, where n is a natural number.

Description

  The present invention relates to a vibrator, an oscillator, an electronic device, a moving body, and a method for manufacturing the vibrator.

  Generally, an electromechanical structure (for example, a vibrator, a filter, a sensor, a motor, etc.) having a mechanically movable structure called a MEMS (Micro Electro Mechanical System) device formed by using a semiconductor microfabrication technology )It has been known. Among these, MEMS resonators are easier to manufacture by incorporating a semiconductor circuit than conventional resonators / resonators that use quartz or dielectrics. Since it is advantageous, its range of use is widened.

  As typical examples of conventional MEMS vibrators, there are known a comb-type vibrator that vibrates in a direction parallel to the substrate surface on which the vibrator is provided, and a beam-type vibrator that vibrates in the thickness direction of the substrate. . A beam-type vibrator is a vibrator composed of a fixed electrode formed on a substrate and a movable electrode disposed on the substrate. The cantilever type (clamped- Known are a free beam, a clamped-clamped beam, and a free-free beam on both ends.

In the free-beam MEMS vibrator at both ends, the vibration node of the movable electrode that vibrates is supported by the support member, so that vibration is less leaked to the substrate and vibration efficiency is high. Patent Document 1 proposes a technique for improving the vibration characteristics by setting the length of the support member to an appropriate length with respect to the vibration frequency.
Patent Document 2 describes a signal processing method in which a plurality of MEMS vibrators (vibrating micromechanical elements) can be used to process a signal with low power consumption.

US Patent No. US6930569B2 Specification Special table 2004-515089 gazette

  However, the MEMS vibrators described in Patent Document 1 and Patent Document 2 have a problem that it is difficult to obtain stable vibration characteristics and desired vibration characteristics when the size is further reduced. More specifically, in general, in a method for manufacturing a beam-type vibrator using MEMS technology, a sacrificial layer such as an oxide film is stacked on an upper layer of a fixed electrode formed on a substrate, and an upper layer of the sacrificial layer is formed. A method is employed in which the movable electrode is released from the substrate and the fixed electrode by removing the sacrificial layer after the movable electrode is formed. Therefore, the movable electrode laminated on the upper layer portion tends to have a shape reflecting the uneven shape of the lower layer portion. For example, in the MEMS vibrator shown in FIG. 2 of Patent Document 1 and FIG. 5a of Patent Document 2 (partially extracted from FIGS. 2A and 2B attached to the present specification), the fixed electrode disposed in the lower layer is used. This pattern shape appears as irregularities on the upper movable electrode. Such unevenness of the movable electrode affects the stiffness of the movable electrode as a vibrating beam. For this reason, when the size of the vibrator is further reduced, this influence is increased, resulting in a problem that stable vibration characteristics and desired vibration characteristics cannot be obtained. More specifically, for example, when the vibrator is viewed in plan, even if the movable electrode (vibrating beam) is arranged in a well-balanced manner, the unevenness of the pattern arranged in the lower layer is reflected, and when viewed from the side In addition, the uneven shape of the vibrating beam may be out of balance. In this case, since the stiffness distribution in the vibrating beam is not uniform, the vibration balance of the vibrating beam is lost. As a result, the vibration efficiency is lowered or the leakage of vibration from the support portion to the outside increases. Led to problems such as. In addition, since the vibrating beam has a complicated shape as described above, there is a problem that the vibration design in manufacturing the vibrator becomes complicated.

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

  Application Example 1 The vibrator according to this application example is separated from the substrate by the substrate, the fixing portion provided on the main surface of the substrate, the support portion extending from the fixing portion, and the support portion. And a vibrating body supported by a vibration node, and the vibration body has 2n rotational symmetry with 2n beams extending radially from the vibration node at a natural number n. It is a body.

According to this application example, the vibration body is supported by the support at the vibration node, and the shape thereof is a 2n-fold rotationally symmetric body having 2n beams extending radially from the vibration node. It has the shape of That is, the 2n beams extending radially from the vibration node have the same shape and are arranged at equal intervals as rotationally symmetric bodies. Therefore, for example, when the vibrator is configured as a beam-type vibrator that vibrates in the thickness direction of the substrate, by reversing the phase of vibration of beams adjacent to each other, the vibration of the entire vibrating body at the vibration node Therefore, vibration leakage from the vibration node supported by the support portion can be suppressed. The same applies to a comb-type vibrator that vibrates in a direction parallel to the substrate surface, and vibration leakage from a vibration node supported by the support portion can be suppressed.
Therefore, according to this application example, it is possible to provide a vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed even when the size is further reduced.

  Application Example 2 A vibrator according to this application example includes a substrate, a lower electrode provided on the main surface of the substrate, a fixing portion provided on the main surface of the substrate, and an extension from the fixing portion. A vibrating body having a region that overlaps the lower electrode when the substrate is viewed in plan view, and the upper electrode is supported by being separated from the substrate by the supporting portion. The support portion supports a vibration node included in the upper electrode as the vibrating body, and the upper electrode has 2n beams extending radially from the vibration node at a natural number n. It is characterized by being a 2n-fold rotationally symmetric body having

According to this application example, the upper electrode as a vibrating body has a vibration node supported by the support, and the shape thereof is 2n times symmetrical with 2n beams extending radially from the vibration node. It exhibits the shape of a rotationally symmetric body. That is, the 2n beams extending radially from the vibration node have the same shape and are arranged at equal intervals as rotationally symmetric bodies. Further, the upper electrode as the vibrating body has a region overlapping with the lower electrode provided on the main surface of the substrate when the substrate is viewed in plan. Therefore, this vibrator can be configured as an electrostatic beam vibrator that vibrates in the thickness direction of the substrate by an AC voltage applied to the lower electrode and the upper electrode. Further, in this configuration, for example, by reversing the vibration phases of the beams adjacent to each other, the vibration of the entire vibrating body is balanced at the vibration node, so the vibration from the vibration node supported by the support portion Leakage can be suppressed.
Therefore, according to this application example, it is possible to provide a vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed even when the size is further reduced.

  Application Example 3 In the vibrator according to the application example described above, a region of the lower electrode that overlaps the upper electrode when the substrate is viewed in plan is a shape of a rotationally symmetric body that is 2n times symmetric. .

  According to this application example, the region of the lower electrode that overlaps with the upper electrode when the substrate is viewed in plan has the shape of a rotationally symmetric body that is 2n times symmetric. By adopting such a configuration, it is possible to provide an electrostatic beam-type vibrator that is more easily manufactured, has higher vibration efficiency, and further suppresses vibration leakage. More specifically, for example, in manufacturing a vibrator, when a sacrificial layer is stacked on the lower electrode and the upper electrode is formed by stacking on the sacrificial layer, the region of the lower electrode that overlaps the upper electrode when viewed in plan Is the shape of a rotationally symmetric body that is 2n-fold symmetric, and therefore the shape of the top electrode unevenness that reflects the unevenness of the region of the lower electrode can be more easily converted to the shape of a rotationally symmetric body that is 2n-fold symmetric. As a result, as described above, it is possible to more easily provide an electrostatic beam-type vibrator in which vibration efficiency is higher and vibration leakage is suppressed by balancing the vibration of the entire vibrating body at the vibration node. it can.

  Application Example 4 In the vibrator according to the application example, the lower electrode is formed such that a region of the lower electrode overlapping the upper electrode in a plan view of the substrate has a 2n-fold rotationally symmetric shape. Has a dummy slit.

  According to this application example, the lower electrode has a dummy slit so that the region of the lower electrode overlapping the upper electrode in a plan view of the substrate has a 2n-fold rotationally symmetric shape. By adopting such a configuration, it is possible to provide an electrostatic beam-type vibrator that is more easily manufactured, has higher vibration efficiency, and further suppresses vibration leakage. Specifically, the lower electrode may be formed in an electrically insulated pattern in a region overlapping with the upper electrode. In this insulating part, since the lower electrode is separated, an uneven shape is formed. On the other hand, even in a portion that does not need to be electrically separated, by forming a dummy slit as in this application example, the region of the lower electrode that overlaps the upper electrode has a shape of a rotationally symmetric body that is 2n-fold symmetric. Can be formed. The lower electrode electrically insulated by the dummy slit can be electrically connected by being connected in a region that does not overlap with the upper electrode in plan view. With such a configuration, for example, in the manufacture of a vibrator, when a sacrificial layer is stacked on the lower electrode and the upper electrode is formed by stacking on the sacrificial layer, the lower portion overlapped when viewed in plan with the upper electrode Since the electrode region has the shape of a rotationally symmetric body that is 2n times symmetric, the shape of the unevenness of the upper electrode that reflects the unevenness of the region of the lower electrode can be easily changed to the shape of a rotationally symmetric body that is 2n times symmetric. it can. As a result, as described above, it is possible to more easily provide an electrostatic beam-type vibrator in which vibration efficiency is higher and vibration leakage is suppressed by balancing the vibration of the entire vibrating body at the vibration node. it can.

  Application Example 5 A method for manufacturing a vibrator according to this application example includes a step of laminating a first conductor layer on a main surface of a substrate, and a step of forming the first conductor layer to form a lower electrode. A layer forming step, a step of laminating a sacrificial layer so as to cover the lower electrode, a step of forming the sacrificial layer to form an opening exposing at least a part of the lower electrode, and the sacrificial layer And a step of laminating a second conductor layer so as to cover the opening, and a vibrating body having a region that overlaps the lower electrode when the substrate is viewed in plan after forming the second conductor layer A second layer forming step of forming an upper electrode, a fixed portion having a region overlapping with the opening, and a support portion extending from the fixed portion and connected to a central portion of the upper electrode; and etching the sacrificial layer In the second layer forming step, In the number n, the upper electrode is formed such that 2n beams extend radially from the center of the upper electrode to form a 2n-fold rotational symmetry body, and the first layer is formed. In the process, the lower electrode is formed in advance so that when the substrate is viewed in plan after the second layer forming step, the region of the lower electrode that overlaps the upper electrode becomes a 2n-fold rotationally symmetric body. It is characterized by leaving.

According to the method for manufacturing a vibrator according to this application example, the upper electrode as the vibrating body is supported by the support at the center, and the shape thereof is 2n having 2n beams extending radially from the center. It is formed in the shape of a rotationally symmetric body that is rotationally symmetric. That is, 2n beams extending radially from the center are formed in the same shape, and are arranged at equal intervals as rotationally symmetric bodies. Further, the upper electrode as the vibrating body is formed to have a region overlapping with the lower electrode provided on the main surface of the substrate when the substrate is viewed in plan. Therefore, the vibrator obtained by this manufacturing method can be configured as an electrostatic beam vibrator that vibrates in the thickness direction of the substrate by an alternating voltage applied to the lower electrode and the upper electrode. Further, in this configuration, for example, by reversing the phases of vibrations of adjacent beams, the central portion of the upper electrode supported by the support portion is configured as a vibration node portion, and the vibration body in the vibration node portion. Since the entire vibration is balanced, vibration leakage from the vibration node supported by the support portion can be suppressed.
Therefore, according to this application example, it is possible to provide a vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed even when the size is further reduced.

  Application Example 6 A vibrator manufacturing method according to this application example includes a step of laminating a first conductor layer on a main surface of a substrate, and a step of forming the lower electrode by forming the first conductor layer. A first layer forming step, a step of laminating a first sacrificial layer so as to cover the lower electrode, a step of grinding the first sacrificial layer and flattening so as to expose the lower electrode, and flattening A step of laminating a second sacrificial layer so as to cover the surface composed of the lower electrode and the first sacrificial layer, and forming the second sacrificial layer so that at least a part of the lower electrode is exposed. Forming a portion, laminating a second conductor layer so as to cover the second sacrificial layer and the opening, forming the second conductor layer, and viewing the substrate in plan view The upper electrode as a vibrating body having a region overlapping with the lower electrode, and the opening overlaps A second layer forming step of forming a fixed portion having a region and a support portion extending from the fixed portion and connected to the central portion of the upper electrode; and etching and removing the first sacrificial layer and the second sacrificial layer In the second layer forming step, in the natural number n, the shape of the upper electrode is a 2n-fold rotationally symmetric body in which 2n beams extend radially from the center of the upper electrode and The upper electrode is formed in such a manner.

According to the method of manufacturing a vibrator according to this application example, the first sacrificial layer laminated so as to cover the lower electrode is ground so that the lower electrode is exposed, and is flat formed by the lower electrode and the first sacrificial layer. A formed surface is formed. Since the upper electrode is formed by being laminated on the second sacrificial layer that is laminated on the flattened surface, the upper electrode is formed in a shape in which unevenness is suppressed without being affected by the lower electrode. In addition, the upper electrode as a vibrating body is supported by a support portion at the center, and the shape thereof is formed in the shape of a 2n-fold rotationally symmetric body having 2n beams extending radially from the center portion. The That is, the 2n beams extending radially from the central portion are formed in the same shape in which unevenness is suppressed, and are arranged at equal intervals as rotationally symmetric bodies. Further, the upper electrode as the vibrating body is formed to have a region overlapping with the lower electrode provided on the main surface of the substrate when the substrate is viewed in plan. Therefore, the vibrator obtained by this manufacturing method can be configured as an electrostatic beam vibrator that vibrates in the thickness direction of the substrate by an alternating voltage applied to the lower electrode and the upper electrode. Further, in this configuration, for example, by reversing the phases of vibrations of adjacent beams, the central portion of the upper electrode supported by the support portion is configured as a vibration node portion, and the vibration body in the vibration node portion. Since the entire vibration is balanced, vibration leakage from the vibration node supported by the support portion can be suppressed.
Therefore, according to this application example, it is possible to provide a vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed even when the size is further reduced.

  Application Example 7 An oscillator according to this application example includes the vibrator according to the application example.

  According to this application example, a higher-performance and smaller oscillator can be provided by utilizing a vibrator having higher vibration efficiency and a smaller size as the oscillator.

  Application Example 8 An electronic apparatus according to this application example includes the vibrator according to the application example.

  According to this application example, it is possible to provide a high-performance and small-sized electronic device by using a vibrator having higher vibration efficiency and a smaller size as the electronic device.

  Application Example 9 A moving object according to this application example includes the vibrator according to the application example.

  According to this application example, a moving body with higher vibration efficiency and superior space utility can be provided by using a vibrator with higher vibration efficiency and a smaller size as the moving body. .

(A)-(d) The top view and sectional drawing of the vibrator | oscillator which concern on Embodiment 1. FIG. (A), (b) The perspective view and sectional drawing which show a part of example of the vibrator | oscillator by a prior art. (A)-(c) The top view and sectional drawing which show the example of the vibrator | oscillator manufactured by the prior art. (A)-(g) Process drawing which shows the manufacturing method of the vibrator | oscillator which concerns on Embodiment 1 in order. (A)-(f) Process drawing which shows the manufacturing method of the vibrator | oscillator which concerns on Embodiment 2 in order. FIG. 3 is a schematic diagram illustrating a configuration example of an oscillator including the vibrator according to the first embodiment. FIG. 4A is a perspective view illustrating a configuration of a mobile personal computer as an example of an electronic apparatus, and FIG. 5B is a perspective view illustrating a configuration of a mobile phone as an example of an electronic apparatus. The perspective view which shows the structure of the digital still camera as an example of an electronic device. The perspective view which shows the motor vehicle as an example of a mobile body roughly. (A)-(c) The top view which shows the example of the variation of an upper electrode as a vibrator | oscillator concerning the modification 1. FIG. (A)-(d) Process drawing which shows the manufacturing method of the vibrator | oscillator which concerns on the modification 2 in order.

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention. In the following drawings, the scale may be different from the actual scale for easy understanding.

(Embodiment 1)
First, the MEMS vibrator 100 as the vibrator according to the first embodiment will be described.
1A is a plan view of the MEMS vibrator 100, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 1C is a cross-sectional view taken along line BB in FIG. Sectional drawing and FIG.1 (d) are CC sectional drawing of Fig.1 (a).
The MEMS vibrator 100 is an electrostatic beam vibrator provided with a fixed electrode (lower electrode) formed on a substrate and a movable electrode (upper electrode) formed free from the substrate and the fixed electrode. is there. The movable electrode is formed free from the substrate and the fixed electrode by etching the main surface of the substrate and the sacrificial layer laminated on the fixed electrode.
Note that the sacrificial layer is a layer once formed of an oxide film or the like, and is removed by etching after forming necessary layers above and around it. By removing the sacrificial layer, necessary gaps and cavities are formed between the upper and lower layers and the surrounding layers, and necessary structures are liberated.

The configuration of the MEMS vibrator 100 will be described below. A method for manufacturing the MEMS vibrator 100 will be described in an embodiment described later.
The MEMS vibrator 100 includes a substrate 1, a lower electrode 10 (first lower electrode 11, second lower electrode 12) and a fixing portion 23 provided on the main surface of the substrate 1, and a support extending from the fixing portion 23. A portion 25 and an upper electrode 20 as a movable electrode supported by being separated from the substrate 1 by the support portion 25 are included.

As the substrate 1, a silicon substrate is used as a preferred example. An oxide film 2 and a nitride film 3 are sequentially laminated on the substrate 1, and a lower electrode 10 (a first lower electrode 11 and a second lower electrode 12 is formed on the main surface of the substrate 1 (the surface of the nitride film 3). ), An upper electrode 20, a fixing portion 23, a support portion 25, and the like.
Here, in the thickness direction of the substrate 1, the direction in which the oxide film 2 and the nitride film 3 are sequentially stacked on the main surface of the substrate 1 is described as an upward direction.

  Among the lower electrodes 10, the second lower electrode 12 is a fixed electrode that fixes the fixing portion 23 on the substrate 1 and applies a potential to the upper electrode 20 through the fixing portion 23 and the support portion 25. As shown in FIG. 1A, the first conductor layer 4 laminated on the film 3 is patterned by photolithography (including an etching process; the same applies hereinafter) to form an H shape. The second lower electrode 12 is connected to an external circuit (not shown) by a wiring 12a.

The fixing portion 23 is provided at each of four ends of the H-shaped second lower electrode 12. The fixing portion 23 is formed by patterning the second conductor layer 5 laminated via a sacrificial layer laminated on the first conductor layer 4 by photolithography. A part of the fixing portion 23 is directly laminated on the second lower electrode 12 through an opening provided in the sacrifice layer.
As the first conductor layer 4 and the second conductor layer 5, conductive polysilicon is used as a suitable example, but the present invention is not limited to this.

The upper electrode 20 is a 2n-fold rotationally symmetric body having 2n beams extending radially from the central portion at a natural number n = 2. Specifically, as shown in FIG. 1A, a movable electrode (vibrating body) having a cross shape by four beams extending from the central portion of the upper electrode 20 is provided around the central portion. Further, it is supported by four support portions 25 extending from the four fixed portions 23. The upper electrode 20 is formed by patterning the second conductor layer 5 laminated via a sacrificial layer laminated on the first conductor layer 4 by photolithography. That is, the four fixing portions 23, the four support portions 25, and the upper electrode 20 are integrally formed.
Further, the H-shaped second lower electrode 12 and the cross-shaped upper electrode 20 overlap each other so that their central portions substantially coincide when the substrate 1 is viewed in plan view, and the lateral direction from the central portion of the upper electrode 20 Two beams extending in the (BB direction) are arranged so as to overlap with the H-shaped second lower electrode 12 (except for a slit S2 described later).

  Among the lower electrodes 10, the first lower electrode 11 is a fixed electrode to which an AC voltage is applied between the lower electrode 10 and the upper electrode 20 that overlaps when the substrate 1 is viewed in plan, and is a first conductive layer laminated on the nitride film 3. The body layer 4 is formed by patterning by photolithography. The first lower electrode 11 is provided at two locations so as to overlap two beams extending in the longitudinal direction (AA direction) from the center of the upper electrode 20 when the front view of FIG. The wiring 11a is connected to an external circuit.

  The first lower electrode 11 is formed of the first conductor layer 4 that is the same layer as the second lower electrode 12. Accordingly, the first lower electrode 11 needs to be electrically insulated from the second lower electrode 12 as a fixed electrode for applying a potential to the upper electrode 20, and the respective patterns (the first lower electrode 11 and the first lower electrode 11) 2 lower electrode 12 and 2) are separated. The step (unevenness) of the gap for separation is uneven in the upper electrode 20 formed by the second conductor layer 5 stacked via the sacrificial layer stacked on the upper layer of the first conductor layer 4. Transcribed. Specifically, as shown in FIGS. 1A and 1B, an uneven shape is formed on the upper electrode 20 in the pattern separation portion (slit S <b> 1).

Since the uneven shape formed on the upper electrode 20 affects the stiffness of the beam as the vibrating body, the vibration characteristics may be adversely affected depending on the shape and position of the unevenness.
2A and 2B are views showing a part of a vibrator 98 according to the prior art (FIG. 5a of Patent Document 2). The vibrator 98 is a doubly-supported vibrator, and both ends of the vibrating body 97 are fixed to the substrate by fixing portions (anchors 18). In addition, two electrodes (strips 24 and 26) are disposed under the vibrating body 97. As can be seen from FIGS. 2A and 2B, the widths of the two electrodes are different and the distances from the fixed portions at both ends are also different. Therefore, the stiffness of the oscillating body 97 due to the uneven shape transferred to the oscillating body 97 is An uneven distribution will be exhibited. Due to this non-uniform stiffness, for example, the resonance peak value of the vibrating body 97 may decrease, or the Q value of vibration may deteriorate.

  FIGS. 3A and 3B show an example of the MEMS vibrator 99 manufactured by the conventional technique without considering the uneven shape transferred to such a vibrating body. The MEMS vibrator 99 is the same as the MEMS vibrator 100 except that the first lower electrode 11 does not have a slit S2, which will be described later, and that the upper electrode 20 is not formed with unevenness transfer by the slit S2. It is configured.

  As shown in FIGS. 3A and 3B, the MEMS vibrator 99 is similar to the MEMS vibrator 100 in the vertical direction (AA) of the upper electrode 20 in the pattern separation portion (slit S1). An uneven shape is formed on the two beams extending in the direction). On the other hand, the two beams extending in the lateral direction (BB direction) of the upper electrode 20 are not formed with uneven shapes as shown in FIG. This is because the second lower electrode 12 extending in the BB direction in the region where the upper electrode 20 is laminated does not have a separation portion or the like and is formed flat. As a result, there is a difference in stiffness between the beam extending in the vertical direction (AA direction) from the central portion of the upper electrode 20 and the beam extending in the horizontal direction (BB direction).

Returning to FIGS. 1A to 1C, the MEMS vibrator 100 will be described.
In the MEMS vibrator 100, there is no difference in stiffness between a beam extending in the vertical direction (AA direction) from the center portion of the upper electrode 20 and a beam extending in the horizontal direction (BB direction). As described above, a dummy slit pattern is provided in the second lower electrode 12. Specifically, the horizontal direction (BB direction) of the upper electrode 20 is similar to the concavo-convex shape in which the slit S1 is reflected in two beams extending in the longitudinal direction (AA direction) of the upper electrode 20. ) Is provided in the second lower electrode 12 extending in the BB direction in the region where the upper electrode 20 overlaps. That is, the width of the slit S2 is substantially the same as the width of the slit S1, and when viewed in plan, the distance from the position where the center point of the upper electrode 20 overlaps to the slit S2 is the same as the center point of the upper electrode 20. The slit S2 is formed so as to be substantially the same as the distance from the overlapping position to the slit S1.

By providing the dummy slit S2 in this manner, the upper electrode 20 including the concavo-convex portion has a 2n-fold rotational symmetry having 2n beams extending radially from the central portion at a natural number n = 2. Configured as a body.
Note that the slit S2 is not formed for the purpose of electrically insulating the second lower electrode 12, and therefore, in a region of both ends of the slit S2 that does not overlap the upper electrode 20 when viewed in plan, The lower electrode 12 is continuous.

  In such a configuration, the MEMS vibrator 100 is configured as an electrostatic vibrator, and the upper part is driven by an AC voltage applied between the first lower electrode 11 and the upper electrode 20 from the external circuit via the wirings 11a and 12a. The tip regions of the four beams of the electrode 20 vibrate as vibration antinodes. In FIG. 1A, the symbol (+/−) indicates a portion that vibrates in the vertical direction (thickness direction of the substrate 1) as a vibration antinode, including its phase relationship. For example, when the + beam moves upward (in a direction away from the substrate 1), the adjacent beam moves in a −down direction (a direction approaching the substrate 1).

As described above, according to the MEMS vibrator 100 according to the present embodiment, the following effects can be obtained.
The central portion of the upper electrode 20 as a vibrating body is supported by a support portion 25 as a vibration node, and the shape thereof has 2n beams extending radially from the central portion at a natural number n = 2. It has the shape of a 2n-fold rotationally symmetric body. That is, 2n = 4 beams extending radially from the central portion (vibration node) have the same shape and are arranged at equal intervals as rotationally symmetric bodies. Further, the upper electrode 20 as the vibrating body has a region overlapping the first lower electrode 11 provided on the main surface of the substrate 1 when the substrate 1 is viewed in plan. Therefore, the MEMS vibrator 100 can be configured as an electrostatic beam vibrator that vibrates in the thickness direction of the substrate 1 by an AC voltage applied to the first lower electrode 11 and the upper electrode 20. Further, in this configuration, for example, by reversing the phases of the vibrations of the beams adjacent to each other, the vibration of the entire vibrating body is balanced at the vibration node, so that the vibration from the vibration node supported by the support unit 25 is reduced. Vibration leakage can be suppressed.
Therefore, according to the present embodiment, there is provided a higher-performance electrostatic beam-type vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed even when the size is further reduced. be able to.

  Also, by providing the dummy slit S2, the region of the first lower electrode 11 that overlaps the upper electrode 20 when the substrate 1 is viewed in plan is configured as a 2n-fold rotationally symmetric body. By adopting such a configuration, it is possible to provide an electrostatic beam-type vibrator that is more easily manufactured, has higher vibration efficiency, and further suppresses vibration leakage. More specifically, the first lower electrode 11 is formed in an electrically insulated pattern in a region overlapping with the upper electrode 20. In this insulating part, since the first lower electrode 11 is separated, an uneven shape is formed. On the other hand, even in a portion that does not need to be electrically separated, by forming a dummy slit S2 as in this embodiment, the region of the first lower electrode 11 that overlaps the upper electrode 20 rotates 2n times symmetrically. It can be formed to have a symmetrical shape. The first lower electrode 11 that is electrically insulated by the dummy slit S2 can be electrically connected by being connected in a region that does not overlap the upper electrode 20 in plan view. With such a configuration, for example, in the manufacture of the vibrator, when a sacrificial layer is stacked on the first lower electrode 11 and the upper electrode 20 is formed by stacking on the sacrificial layer, the upper electrode 20 and a plan view are formed. Since the region of the first lower electrode 11 that overlaps with the shape of a rotationally symmetric body that is 2n-fold symmetric, the shape of the unevenness of the upper electrode 20 that reflects the unevenness of the region of the first lower electrode 11 can be easily 2n. It can be made into the shape of a rotationally symmetric body of a rotational symmetry. As a result, as described above, it is possible to more easily provide an electrostatic beam-type vibrator in which vibration efficiency is higher and vibration leakage is suppressed by balancing the vibration of the entire vibrating body at the vibration node. it can.

(Embodiment 2)
Next, a method for manufacturing the vibrator (MEMS vibrator 100) according to Embodiment 1 as Embodiment 2 will be described. In the description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
4A to 4G are process diagrams sequentially illustrating a method for manufacturing the MEMS vibrator 100. The aspect of the MEMS vibrator 100 in each step is shown in the AA sectional view and the BB sectional view in FIG.

In the method for manufacturing the vibrator according to the present embodiment, the step of laminating the first conductor layer 4 on the main surface of the substrate 1, and forming the first conductor layer 4 to form the lower electrode 10 (first lower electrode 11). And a second lower electrode 12), a first layer forming step, a step of laminating a sacrificial layer so as to cover the first lower electrode 11 and the second lower electrode 12, a sacrificial layer being formed, and a second lower portion Forming the opening 30 where at least a part of the electrode 12 is exposed, laminating the second conductor layer 5 so as to cover the sacrificial layer and the opening 30, and forming the second conductor layer 5 The upper electrode 20 as a vibrating body having a region overlapping with the first lower electrode 11 when the substrate 1 is viewed in plan, the fixing portion 23 having a region overlapping with the opening 30, and the upper electrode 20 extending from the fixing portion 23 The second layer forming step for forming the support portion 25 connected to the central portion of the second layer In the second layer forming step, the shape of the upper electrode 20 is radiated from the central portion of the upper electrode 20 in a radiating manner and is symmetric 2n times in the second layer forming step. The upper electrode 20 is formed so as to be a rotationally symmetric body. In the first layer forming step, when the substrate 1 is viewed in plan after the second layer forming step, the region of the lower electrode 10 overlapping the upper electrode 20 is 2n. The lower electrode 10 is formed in advance so as to be a rotationally symmetric body having a rotational symmetry.
This will be specifically described below.

FIG. 4A: A substrate 1 is prepared, and an oxide film 2 is laminated on the main surface. As a preferred example, the oxide film 2 is formed of a local LOCOS (Local Oxidation of Silicon) oxide film as an element isolation layer of a semiconductor process. However, depending on the generation of the semiconductor process, for example, an STI (Shallow Trench Isolation) method is used. An oxide film may be used.
Next, a nitride film 3 as an insulating layer is stacked. As the nitride film 3, Si ₃ N _{4 is formed} by LPCVD (Low Pressure Chemical Vapor Deposition). The nitride film 3 is resistant to buffered hydrofluoric acid as an etchant used for release etching of the sacrificial layer, and functions as an etching stopper.

  4B and 4C: Next, as the first layer forming step, first, the first conductor layer 4 is laminated on the nitride film 3. The first conductor layer 4 is a polysilicon layer constituting the lower electrode 10 (first lower electrode 11, second lower electrode 12), wirings 11a, 12a (see FIG. 1A), etc. Injection is performed to give a predetermined conductivity. Next, a resist 6 is applied to the first conductor layer 4 and patterned by photolithography to form a first lower electrode 11, a second lower electrode 12, and wirings 11a and 12a. In the first layer forming step, when the substrate 1 is viewed in plan after the second layer forming step, the lower electrode 10 in advance so that the region of the lower electrode 10 that overlaps the upper electrode 20 becomes a 2n-fold rotationally symmetric body. That is, the first lower electrode 11 and the second lower electrode 12 are formed in advance.

  FIG. 4D: Next, the sacrificial layer 7 is laminated so as to cover the lower electrode 10 and the wirings 11a and 12a. The sacrificial layer 7 is a sacrificial layer for forming a gap between the first lower electrode 11 and the second lower electrode 12 and the upper electrode 20 and releasing the upper electrode 20, and is formed of a CVD (Chemical Vapor Deposition) oxide film. doing. In the laminated sacrificial layer 7, irregularities due to steps such as the patterned first lower electrode 11 and second lower electrode 12 appear.

  FIG. 4E: Next, the sacrificial layer 7 is patterned by photolithography to form an opening 30 through which a part of the second lower electrode 12 is exposed. The opening 30 forms a bonding region where the fixing unit 23 is bonded to and fixed to the second lower electrode 12. Since the bonding region is a region where the upper electrode 20 is supported by the substrate 1 via the support portion 25, an area where necessary stiffness is obtained is opened.

  FIG. 4F: Next, as the second layer forming step, first, the second conductor layer 5 is laminated so as to cover the sacrificial layer 7 and the opening 30. The second conductor layer 5 is the same polysilicon layer as the first conductor layer 4, and is patterned by photolithography after lamination to form the upper electrode 20, the fixing part 23, and the support part 25. As shown in FIG. 1A, the upper electrode 20 is an electrode having a region that overlaps the first lower electrode 11 and the second lower electrode 12 when the substrate 1 is viewed in plan view. The shape is formed so that 2n beams extend radially from the center of the upper electrode 20 and become a 2n-fold rotationally symmetric body. Further, ion implantation is performed after stacking to give a predetermined conductivity.

FIG. 4G: Next, the substrate 1 is exposed to an etching solution (buffered hydrofluoric acid), and the sacrificial layer 7 is removed by etching (release etching). A gap with the electrode 20 is formed, and the upper electrode 20 is released.
Thus, the MEMS vibrator 100 is formed.

  Note that the MEMS vibrator 100 is preferably installed in a hollow portion sealed in a reduced pressure state. Therefore, in manufacturing the MEMS vibrator 100, the sacrificial layer for forming the cavity, the side wall surrounding the sacrificial layer, the sealing layer for forming the lid of the cavity, etc. are formed together. The description is omitted here.

As described above, according to the method for manufacturing a vibrator according to the present embodiment, the following effects can be obtained.
The upper part of the upper electrode 20 as a vibrating body is supported by a support part 25 at the center, and the shape thereof is formed in the shape of a 2n-fold rotationally symmetric body having 2n beams extending radially from the center. The That is, 2n beams extending radially from the center are formed in the same shape, and are arranged at equal intervals as rotationally symmetric bodies. Further, the upper electrode 20 as a vibrating body is formed to have a region overlapping with the first lower electrode 11 provided on the main surface of the substrate 1 when the substrate 1 is viewed in plan. Therefore, the vibrator obtained by this manufacturing method is configured as an electrostatic beam vibrator that vibrates in the thickness direction of the substrate 1 by an alternating voltage applied to the first lower electrode 11 and the upper electrode 20.
In this configuration, for example, the center portion of the upper electrode 20 supported by the support portion 25 is configured as a vibration node portion by reversing the phases of vibrations of the beams adjacent to each other. Since the entire vibration is balanced, vibration leakage from the vibration node supported by the support portion 25 can be suppressed.
Therefore, according to the method for manufacturing a vibrator according to the present embodiment, even when the size is further reduced, a decrease in vibration efficiency is suppressed, and a higher performance electrostatic beam in which vibration leakage is suppressed. A type resonator can be provided.

(Embodiment 3)
Next, a method for manufacturing the vibrator (MEMS vibrator 100) according to Embodiment 1 as Embodiment 3 will be described. In the description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
5A to 5F are process diagrams sequentially showing a method for manufacturing the MEMS vibrator 100. FIG. The aspect of the MEMS vibrator 100 in each step is shown in the AA sectional view and the BB sectional view in FIG.

The method for manufacturing a vibrator according to the present embodiment reduces or eliminates the unevenness formed on the upper electrode 20 by planarizing the sacrificial layer 7 as compared with the method for manufacturing the vibrator according to the second embodiment. It is a feature.
The method for manufacturing a vibrator according to the present embodiment includes a step of laminating the first conductor layer 4 on the main surface of the substrate 1 and a first layer for forming the lower electrode 10 by forming the first conductor layer 4. Forming the first sacrificial layer 8 so as to cover the lower electrode 10, grinding the first sacrificial layer 8 and flattening so that the lower electrode 10 is exposed, and flattened lower part A step of laminating the second sacrificial layer 9 so as to cover the surface constituted by the electrode 10 and the first sacrificial layer 8, and forming the second sacrificial layer 9 so that at least a part of the lower electrode 10 is exposed. Forming the portion 30, laminating the second conductor layer 5 so as to cover the second sacrificial layer 9 and the opening 30, forming the second conductor layer 5, and viewing the substrate 1 in plan view The upper electrode 20 as a vibrator having a region that sometimes overlaps the lower electrode 10 and the region that overlaps the opening 30 A second layer forming step of forming a fixing portion 23 having a supporting portion 25 extending from the fixing portion 23 and connected to a central portion of the upper electrode 20, and a sacrificial layer (first sacrificial layer 8 and second sacrificial layer 9). In the second layer forming step, the shape of the upper electrode 20 is radially extended from the central portion of the upper electrode 20 in a natural number n, and is rotated 2n times symmetrically. The upper electrode 20 is formed so as to be a symmetric body.
This will be specifically described below.

  FIG. 5A: First, similarly to the second embodiment, the process proceeds to the first layer forming step shown in FIG. Next, the first sacrificial layer 8 is laminated so as to cover the lower electrode 10 (first lower electrode 11 and second lower electrode 12) and wirings 11a and 12a (see FIG. 1A). The first sacrificial layer 8 is a sacrificial layer for filling a step (unevenness) formed by patterning with respect to the first conductor layer 4, and is formed of, for example, a CVD (Chemical Vapor Deposition) oxide film.

FIG. 5B: Next, the first sacrificial layer 8 is ground to expose the first conductor layer 4 (the lower electrode 10 (the first lower electrode 11 and the second lower electrode 12) and the wirings 11a and 12a). So that it is flattened. The grinding is performed by, for example, CMP (Chemical Mechanical Polishing).
The flattening step after the first layer forming step is not limited to the method of flattening the CVD oxide film by CMP. For example, as the interlayer film (IMD (Inter Metal Dielectric)) used in the semiconductor process, A flattening method using TEOS (Tetraethoxysilane) may be used.

  FIG. 5C: Next, the second sacrificial layer 9 is laminated so as to cover the planarized surface. The second sacrificial layer 9 is a sacrificial layer that forms a gap between the first lower electrode 11 and the second lower electrode 12 and the upper electrode 20 and releases the upper electrode 20, and is a CVD (Chemical Vapor Deposition) oxide film. It is formed with. The laminated second sacrificial layer 9 has an uneven surface (patterned first lower electrode 11 and second sacrificial layer 7 as in the sacrificial layer 7 in the second embodiment) as a result of the planarization of the laminated surface by the first sacrificial layer 8. There is no unevenness due to steps such as the lower electrode 12.

  FIG. 5D: Next, the second sacrificial layer 9 is patterned by photolithography to form an opening 30 where a part of the second lower electrode 12 is exposed (not shown), and then the second layer is formed. As a process, first, the second conductor layer 5 is laminated so as to cover the second sacrificial layer 9 and the opening 30.

  FIG. 5E: Next, as the second layer forming step, the second conductor layer 5 is patterned by photolithography to form the upper electrode 20, the fixing portion 23, and the support portion 25 (not shown). As shown in FIG. 1A, the upper electrode 20 is an electrode having a region that overlaps the first lower electrode 11 and the second lower electrode 12 when the substrate 1 is viewed in plan view. The shape is formed so that 2n beams extend radially from the center of the upper electrode 20 and become a 2n-fold rotationally symmetric body. Further, ion implantation is performed after stacking to give a predetermined conductivity.

FIG. 5F: Next, the substrate 1 is exposed to an etching solution, and the sacrificial layers (the first sacrificial layer 8 and the second sacrificial layer 9) are removed by etching.
Thus, the MEMS vibrator 100 is formed.

As described above, according to the method for manufacturing a vibrator according to the present embodiment, the following effects can be obtained.
The first sacrificial layer 8 laminated so as to cover the lower electrode 10 (the first lower electrode 11 and the second lower electrode 12) and the wirings 11a and 12a is ground to form a flattened surface. Since the upper electrode 20 is formed by being laminated on the second sacrificial layer 9 that is laminated on the planarized surface, the upper electrode 20 is formed in a shape in which unevenness is suppressed without being affected by the lower electrode 10. The upper electrode 20 as a vibrating body is supported at the center by a support 25, and the shape thereof is a 2n-fold rotationally symmetric body having 2n beams extending radially from the center. It is formed. That is, the 2n beams extending radially from the central portion are formed in the same shape in which unevenness is suppressed, and are arranged at equal intervals as rotationally symmetric bodies. Further, the upper electrode 20 as a vibrating body is formed to have a region overlapping with the first lower electrode 11 provided on the main surface of the substrate 1 when the substrate 1 is viewed in plan. Therefore, the vibrator obtained by this manufacturing method is configured as an electrostatic beam vibrator that vibrates in the thickness direction of the substrate 1 by an AC voltage applied between the first lower electrode 11 and the upper electrode 20. be able to.
Further, in this configuration, for example, by reversing the vibration phases of the beams adjacent to each other, the central portion of the upper electrode 20 supported by the support portion 25 is configured as a vibration node portion. Since the vibration of the entire vibrating body is balanced, vibration leakage from the vibration node supported by the support portion 25 can be suppressed.
Therefore, according to the method for manufacturing a vibrator according to the present embodiment, even when the size is further reduced, a decrease in vibration efficiency is suppressed, and a higher performance electrostatic beam in which vibration leakage is suppressed. A type resonator can be provided.

[Oscillator]
Next, an oscillator 200 to which the MEMS vibrator 100 as an oscillator according to an embodiment of the present invention is applied will be described with reference to FIG.

FIG. 6 is a schematic diagram illustrating an example of the configuration of an oscillator including the MEMS resonator 100 according to an embodiment of the present invention. The oscillator 200 includes a MEMS vibrator 100, a bias circuit 70, amplifiers 71 and 72, and the like.
The bias circuit is a circuit that is connected to the wirings 11 a and 12 a of the MEMS vibrator 100 and applies an alternating voltage with a predetermined potential biased to the MEMS vibrator 100.
The amplifier 71 is a feedback amplifier connected to the wirings 11 a and 12 a of the MEMS vibrator 100 in parallel with the bias circuit. By performing feedback amplification, the MEMS vibrator 100 is configured as an oscillator.
The amplifier 72 is a buffer amplifier that outputs an oscillation waveform.

  According to the present embodiment, it is possible to provide a smaller oscillator with higher performance by utilizing a vibrator having higher vibration efficiency and a smaller size as the oscillator.

[Electronics]
Next, an electronic apparatus to which the MEMS vibrator 100 as an electronic component according to an embodiment of the present invention is applied will be described with reference to FIGS. 7 (a), 7 (b), and 8. FIG.

  FIG. 7A is a perspective view schematically illustrating a configuration of a mobile (or notebook) personal computer as an electronic apparatus including an electronic component according to an embodiment of the present invention. In this figure, a personal computer 1100 includes a main body portion 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display portion 1000. The display unit 1106 is rotated with respect to the main body portion 1104 via a hinge structure portion. It is supported movably. Such a personal computer 1100 incorporates a MEMS vibrator 100 as an electronic component that functions as a filter, a resonator, a reference clock, and the like.

  FIG. 7B is a perspective view schematically showing a configuration of a mobile phone (including PHS) as an electronic apparatus including the electronic component according to the embodiment of the present invention. In this figure, a cellular phone 1200 is provided with a plurality of operation buttons 1202, an earpiece 1204 and a mouthpiece 1206, and a display unit 1000 is disposed between the operation buttons 1202 and the earpiece 1204. Such a cellular phone 1200 incorporates a MEMS vibrator 100 as an electronic component (timing device) that functions as a filter, a resonator, an angular velocity sensor, or the like.

FIG. 8 is a perspective view schematically illustrating a configuration of a digital still camera as an electronic apparatus including the electronic component according to the embodiment of the present invention. In this figure, connection with an external device is also simply shown. The digital still camera 1300 generates an imaging signal (image signal) by photoelectrically converting an optical image of a subject using an imaging element such as a CCD (Charge Coupled Device).
A display unit 1000 is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to display based on an image pickup signal from the CCD. The display unit 1000 displays an object as an electronic image. Functions as a viewfinder. A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side (the back side in the drawing) of the case 1302.
When the photographer confirms the subject image displayed on the display unit 1000 and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory 1308. In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the input / output terminal 1314 for data communication as necessary. Further, the imaging signal stored in the memory 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation. Such a digital still camera 1300 includes a MEMS vibrator 100 as an electronic component that functions as a filter, a resonator, an angular velocity sensor, or the like.

  As described above, a higher-performance and smaller electronic device can be provided by utilizing a vibrator having higher vibration efficiency and a smaller size as the electronic device.

  The MEMS vibrator 100 as an electronic component according to an embodiment of the present invention includes a personal computer (mobile personal computer) in FIG. 7A, a mobile phone in FIG. 7B, and a digital still camera in FIG. In addition, for example, an ink jet discharge device (for example, an ink jet printer), a laptop personal computer, a television, a video camera, a car navigation device, a pager, an electronic notebook (including a communication function), an electronic dictionary, a calculator, an electronic Game equipment, workstations, videophones, crime prevention TV monitors, electronic binoculars, POS terminals, medical equipment (eg electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasonic diagnostic devices, electronic endoscopes), fish detection Machines, various measuring instruments, instruments (eg, vehicles, aircraft, ships Vessels such) can be applied to electronic devices such as flight simulators.

[Moving object]
Next, a moving body to which the MEMS vibrator 100 as a vibrator according to an embodiment of the present invention is applied will be described with reference to FIG.
FIG. 9 is a perspective view schematically showing an automobile 1400 as a moving body including the MEMS vibrator 100. The automobile 1400 is equipped with a gyro sensor including the MEMS vibrator 100 according to the present invention. For example, as shown in the figure, an automobile 1400 as a moving body is equipped with an electronic control unit 1402 incorporating the gyro sensor for controlling the tire 1401. As another example, the MEMS vibrator 100 includes a keyless entry, an immobilizer, a car navigation system, a car air conditioner, an anti-lock brake system (ABS), an air bag, a tire pressure monitoring system (TPMS: Tire Pressure Monitoring). System), engine control, battery monitors for hybrid vehicles and electric vehicles, vehicle body attitude control systems, and other electronic control units (ECUs).

  As described above, a moving body with higher vibration efficiency and superior space utility can be provided by using a vibrator having higher vibration efficiency and a smaller size as the moving body.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below. Here, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

(Modification 1)
10A to 10C are plan views illustrating examples of variations of the upper electrode as the vibrator according to the first modification.
In the first embodiment, as illustrated in FIG. 1A, the upper electrode 20 has been described as a vibrating body having a cross shape with four beams extending from the central portion of the upper electrode. However, the configuration is limited to this configuration. Not what you want. In the natural number n, it is only necessary that the upper electrode is formed so that 2n beams extend radially from the vibration node and become a 2n-fold rotationally symmetric body.

  FIG. 10A shows an example of the upper electrode 20a in which the upper electrode is formed in a disc shape. Even in the upper electrode having such a shape, the unevenness formed on the upper electrode by the pattern shape of the lower electrode may be formed so as to be a four-fold rotational symmetry body. When vibrating so that the vibration phases of beams adjacent to each other are reversed, it is possible to provide a beam type vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed.

  FIG. 10B shows an example of the upper electrode 20b when the natural number n = 3. Even in the upper electrode having such a shape, for example, the unevenness formed on the upper electrode depending on the pattern shape of the lower electrode may be formed so as to be a six-fold rotationally symmetric body. When vibrating so that the vibration phases of beams adjacent to each other are reversed, it is possible to provide a beam type vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed.

  FIG. 10C shows an example of the upper electrode 20c when the natural number n = 4. Even in the upper electrode having such a shape, for example, the unevenness formed on the upper electrode by the pattern shape of the lower electrode may be formed so as to be an 8-fold rotationally symmetric body. When the beams vibrate adjacent to each other, the two beams adjacent to each other vibrate in the same phase as one set, as shown in FIG. In the case of vibrating so that their phases are reversed, it is possible to provide a beam-type vibrator in which a decrease in vibration efficiency is suppressed and vibration leakage is suppressed.

(Modification 2)
11A to 11D are process diagrams sequentially illustrating a method for manufacturing a vibrator according to the second modification.
In the third embodiment, it is described that the first sacrificial layer 8 is flattened to reduce or eliminate the unevenness formed on the upper electrode 20. However, the upper electrode 20 has the unevenness on the lower electrode 10. It is also possible to form new irregularities that are not involved. This will be specifically described below.

  FIG. 11A: First, similarly to the third embodiment, the upper electrode 20 is formed by proceeding to the second layer forming step shown in FIG.

  11 (b) and 11 (c): Next, a resist 50 is applied to the upper electrode 20 and the second sacrificial layer 9, and a region for forming a recess as a new unevenness of the upper electrode 20 is half-etched by photography To do.

  FIG. 11D: Next, the substrate 1 is exposed to an etching solution, and the sacrificial layers (the first sacrificial layer 8 and the second sacrificial layer 9) are removed by etching.

  In the manufacturing method according to this modification, a new concave portion 51 is formed on the upper electrode 20 by half etching. This new recess 51 controls the stiffness distribution of the upper electrode 20, and as a vibrating body that vibrates in the vertical direction by forming the recess 51 having a desired shape or a desired depth at a desired position. A desired change can be given to the vibration characteristics of the upper electrode. For example, it can be utilized when the vibration characteristics of the upper electrode in which unevenness is suppressed is improved by the manufacturing method according to the third embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Oxide film, 3 ... Nitride film, 4 ... 1st conductor layer, 5 ... 2nd conductor layer, 6 ... Resist, 7 ... Sacrificial layer, 8 ... 1st sacrificial layer, 9 ... 2nd Sacrificial layer, 10 ... lower electrode, 11 ... first lower electrode, 11a, 12a ... wiring, 12 ... second lower electrode, 20 ... upper electrode, 23 ... fixing part, 25 ... support part, 30 ... opening, 100 ... MEMS vibrator.

(Embodiment 2)
Next, a method for manufacturing the vibrator (MEMS vibrator 100) according to Embodiment 1 as Embodiment 2 will be described. In the description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
4A to 4G are process diagrams sequentially illustrating a method for manufacturing the MEMS vibrator 100. The aspect of the MEMS vibrator 100 in each step is shown in the AA sectional view and the CC sectional view in FIG.

Claims (9)

A substrate,
A fixing portion provided on the main surface of the substrate;
A support portion extending from the fixed portion;
A vibration body that is separated from the substrate by the support portion and supported by vibration nodes;
The vibrator is a 2n-fold rotationally symmetric body having 2n beams extending radially from the vibration node at a natural number n. A substrate,
A lower electrode provided on the main surface of the substrate;
A fixing portion provided on the main surface of the substrate;
A support portion extending from the fixed portion;
An upper electrode supported by the support portion so as to be separated from the substrate,
The upper electrode is a vibrating body having a region overlapping the lower electrode when the substrate is viewed in plan view,
The support portion supports a vibration node included in the upper electrode as the vibrating body,
The vibrator is characterized in that the upper electrode is a 2n-fold rotationally symmetric body having 2n beams extending radially from the vibration node at a natural number n.   The vibrator according to claim 2, wherein a region of the lower electrode that overlaps the upper electrode when the substrate is viewed in plan is a shape of a rotationally symmetric body that is 2n times symmetric.   The lower electrode has a dummy slit so that a region of the lower electrode overlapping the upper electrode in a plan view of the substrate has a 2n-fold rotationally symmetric shape. The vibrator according to claim 3. Laminating a first conductor layer on the main surface of the substrate;
A first layer forming step of forming the lower electrode by forming the first conductor layer;
Laminating a sacrificial layer so as to cover the lower electrode;
Forming the sacrificial layer to form an opening exposing at least a portion of the lower electrode;
Laminating a second conductor layer so as to cover the sacrificial layer and the opening;
An upper electrode as a vibrating body having a region overlapping with the lower electrode when the second conductor layer is formed and the substrate is viewed in plan, a fixing portion having a region overlapping with the opening, and the fixing portion A second layer forming step of forming a support portion extending from the center portion of the upper electrode and connected to the center portion;
Etching away the sacrificial layer,
In the second layer forming step, at the natural number n, the upper electrode is shaped so that 2n beams radiate from the central portion of the upper electrode and become a 2n-fold rotationally symmetric body. Forming,
In the first layer forming step, when the substrate is viewed in plan after the second layer forming step, the lower electrode is preliminarily set so that the region of the lower electrode overlapping the upper electrode has a rotational symmetry of 2n times symmetry. A method for manufacturing a vibrator, characterized by comprising: Laminating a first conductor layer on the main surface of the substrate;
A first layer forming step of forming the lower electrode by forming the first conductor layer;
Laminating a first sacrificial layer so as to cover the lower electrode;
Grinding the first sacrificial layer and planarizing so that the lower electrode is exposed;
Laminating a second sacrificial layer so as to cover the planarized lower electrode and the surface composed of the first sacrificial layer;
Forming the second sacrificial layer to form an opening exposing at least a portion of the lower electrode;
Laminating a second conductor layer to cover the second sacrificial layer and the opening;
An upper electrode as a vibrating body having a region overlapping with the lower electrode when the second conductor layer is formed and the substrate is viewed in plan, a fixing portion having a region overlapping with the opening, and the fixing portion A second layer forming step of forming a support portion extending from the center portion of the upper electrode and connected to the center portion;
Etching away the first sacrificial layer and the second sacrificial layer,
In the second layer forming step, at the natural number n, the upper electrode is shaped so that 2n beams radiate from the central portion of the upper electrode and become a 2n-fold rotationally symmetric body. A method for manufacturing a vibrator, comprising: forming the vibrator.   An oscillator comprising the vibrator according to any one of claims 1 to 4.   An electronic apparatus comprising the vibrator according to any one of claims 1 to 4.   A moving body comprising the vibrator according to any one of claims 1 to 4.

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