JP4632029B2 - MEMS resonator and method for manufacturing MEMS resonator - Google Patents

Description

  The present invention relates to a MEMS resonator formed by using a semiconductor manufacturing process and a manufacturing method thereof.

With the progress of microfabrication technology, so-called micro-machines (MEMS) devices are attracting attention.
Conventionally, a lower electrode made of polysilicon provided on a substrate, an interlayer insulating film provided in a state of covering the substrate and having a hole pattern with the lower electrode as a bottom, and an upper portion of the hole pattern as a space portion. A MEMS element having a vibrator electrode (upper electrode) made of polysilicon, which is provided on the interlayer insulating film so as to cross, and the vibrator electrode is provided in a concave shape along the side wall of the hole pattern Is known (see, for example, Patent Document 1).

JP 2004-181567 A (pages 5-7, FIGS. 1-3)

  In such Patent Document 1, the vibrator electrode (upper electrode) and the lower electrode are formed of polysilicon, and a dedicated sacrificial layer is formed by a CVD method or the like to form a gap between the upper electrode and the lower electrode. It is formed by means. In such a structure or manufacturing method, there is a problem that the number of steps increases as a manufacturing method using the CMOS manufacturing process. Further, the formation of the sacrificial layer by the CVD method has a problem that it is difficult to form a narrow inter-electrode gap between the upper electrode and the lower electrode with high accuracy.

  An object of the present invention is to solve the above-described problems, and without using a special manufacturing method for forming a MEMS resonator, a high-accuracy electrode between the upper electrode and the lower electrode can be formed in a CMOS manufacturing process. An object of the present invention is to provide a MEMS resonator capable of forming a void and thereby obtaining a stable vibration mode and vibration frequency, and a manufacturing method capable of shortening the manufacturing process.

A vibrating body having an upper electrode portion and a beam portion formed by a semiconductor manufacturing process on the surface of the semiconductor substrate, and a gap provided by a sacrificial layer formed by gate oxidation between the vibrating body and the semiconductor substrate; And a lower electrode formed by providing a diffusion layer on the semiconductor substrate so as to face the upper electrode portion.
Here, for example, polysilicon is employed as the vibrating body.

  According to this invention, the vibrator is formed of polysilicon, the lower electrode is formed of the diffusion layer, and the gap between the upper electrode portion and the lower electrode is provided by the sacrificial layer formed by gate oxidation. Compared with the above-described conventional technique in which both the upper electrode portion and the lower electrode are formed of polysilicon, a very small distance (distance between electrodes) between the upper electrode portion and the lower electrode can be formed with high accuracy. And stable vibration mode and frequency characteristics can be obtained. In addition, since the diffusion layer can be formed by a diffusion layer forming process using a commonly used CMOS manufacturing process, the manufacturing process can be shortened.

Further, the gap includes a first gap in which the upper electrode portion and the lower electrode face each other, and a second gap in which the beam portion of the vibrating body and the semiconductor substrate face each other. It is preferable that
Here, the first gap is a management gap of the distance between the upper and lower electrodes, which is one of the requirements governing the vertical vibration of the vibrating body, and the second gap is when the vibrating body vibrates. This is a management gap that is set so that the vibrating body and the surface of the semiconductor substrate do not contact each other.

  Accordingly, with such a structure, the first gap in which the upper electrode portion and the lower electrode face each other can limit the management range in the planar direction, so that the inter-electrode distance can be managed with high accuracy. In addition, since the second gap may be controlled more loosely than the first gap, the manufacturing yield can be improved.

Moreover, it is preferable that the surface shape of the said upper electrode part and the said lower electrode is formed in the substantially same shape.
In this case, since the movement of electric charges between the upper electrode portion and the lower electrode is difficult to disperse outside the range of the upper and lower electrodes, the vibrator can be driven efficiently.

  In the structure of the present invention, the lower electrode is preferably divided into a plurality of parts.

  In this way, desired frequency characteristics can be easily obtained by selectively forming the number of lower electrodes and the interval and size of each of the divided lower electrodes. Since the lower electrode is formed of the diffusion layer as described above, the details will be described in the embodiments described later. However, the number of electrodes, the interval and size of each electrode can be freely selected by the CMOS manufacturing process. Can be formed.

Further, in the structure of the present invention, a projecting portion projecting on both sides in the width direction at a substantially central portion in the longitudinal direction of the vibrating body, and the lower electrode provided to face the upper electrode portion including the projecting portion, It is preferable that it is provided.
In addition, as a projection part, it can provide in a comb-tooth shape in the width direction, for example.

  As described above, since the projecting portion is provided on the vibrating body and the lower electrode facing the projecting portion is provided, different vibration modes and frequency characteristics can be obtained by appropriately setting the position, size, and shape of the projecting portion. A MEMS resonator having the above can be easily provided.

  Moreover, it is preferable that the beam part of the vibrating body is formed in the same plane parallel to the surface of the semiconductor substrate.

  In this way, since the beam portion as the vibration portion of the vibrating body has a simple beam shape, the vibration mode can be simplified and designed, and thus stable frequency characteristics can be obtained. Further, since the shape of the vibrating body is simple, it is easy to manufacture and management in manufacturing becomes easy, so that manufacturing efficiency can be increased.

  Furthermore, it is desirable that the surface of the lower electrode is formed in the same plane as the surface of the semiconductor substrate in a plane range where the beam portion of the vibrator is formed.

  According to this configuration, since the surface of the semiconductor substrate facing the beam portion as the vibrating portion of the vibrating body is formed on the same plane, a stable vibration mode can be obtained.

A method for manufacturing a MEMS resonator according to the present invention is a method for manufacturing a MEMS resonator in which a vibrating body having an upper electrode portion and a beam portion is formed on a semiconductor substrate by a semiconductor manufacturing process. A step of forming an insulating layer by element isolation by selective oxidation, and a gap forming layer between the upper electrode portion and the lower electrode formed on the semiconductor substrate, the insulating layer being separated being continuous. A gate oxidation step for forming a sacrificial layer, a diffusion layer formation step for forming a diffusion layer as the lower electrode, a step for forming the vibrator on the upper surface of the sacrificial layer, and a step for removing the sacrificial layer , Including.
Here, as a semiconductor manufacturing process, it is most preferable to employ a CMOS manufacturing process.

  According to the manufacturing method of the present invention, a vibrating body having an upper electrode portion, a lower electrode made of a diffusion layer, and a sacrificial layer for forming a gap between the upper electrode portion and the lower electrode are formed by a semiconductor manufacturing process. Therefore, the number of steps can be reduced, and the production efficiency can be increased. In addition, since a sacrificial layer for forming a gap between the upper electrode portion and the lower electrode is formed by the gate oxidation process, a very narrow gap (interelectrode distance) can be formed with high accuracy.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view and a cross-sectional view showing a MEMS resonator according to a first embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views showing a method for manufacturing the MEMS resonator, and FIG. 4 is a MEMS according to the second embodiment. FIG. 5 is a plan view showing a MEMS resonator according to the third embodiment, FIG. 6 is a sectional view showing the MEMS resonator according to the fourth embodiment, and FIG. 7 is an embodiment. 5 is a cross-sectional view according to FIG.
(Embodiment 1)

1A is a plan view of the MEMS resonator according to the first embodiment, FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A, and FIG. BB sectional view of 1 (a) is shown. 1A to 1C, a MEMS resonator 10 according to this embodiment includes a lower electrode made of a diffusion layer formed on a surface of a semiconductor substrate 20 made of an Si layer by a diffusion layer forming step described later. 50 and a vibrating body 30 having a first gap 35 on the upper surface of the lower electrode 50 and made of polysilicon.
Although not shown, the semiconductor substrate 20 includes a plurality of circuit elements such as transistors, and these circuit elements are drive control circuits that drive and control the MEMS elements. A vibrating body (beam) 30 is formed integrally with the semiconductor substrate 20 including such a drive control circuit.

  Anchor connection portions 26 and 27 are formed on the semiconductor substrate 20 so as to protrude from the surface of the semiconductor substrate 20 (see FIG. 1C). A lower electrode 50 is formed at the center of the straight line connecting the anchor connecting portions 26 and 27. Anchor portions 33 and 34 of the vibrating body 30 are connected to the anchor connection portions 26 and 27, respectively.

The vibrating body 30 is formed in a strip shape formed on the upper surface of the semiconductor substrate 20 by a semiconductor manufacturing process, and anchor portions 33 and 34 are formed at both ends so as to protrude toward the semiconductor substrate 20. In addition, an upper electrode portion 31 that protrudes toward the lower electrode 50 is formed at a linear central portion that connects the anchor portions 33 and 34. The vibrating body 30 is a both-end support beam with the anchor portions 33 and 34 as fulcrums, and between the anchor portion 33 and the upper electrode portion 31, and between the upper electrode portion 31 and the anchor portion 34, the vibrating beam portions 32A and 32B. It is.
In the present invention, the upper electrode portion 31 is integrally formed of the same material as that of the vibrating body 30. However, since the upper electrode portion 31 vibrates by repeatedly sucking and repelling with the lower electrode 50, the upper electrode portion 31 is particularly formed. This will be described as a part.

  A first gap 35 and a second gap 36 formed by the sacrificial layer 25 (see FIG. 2E) are formed between the vibrator 30 and the semiconductor substrate 20. The first gap 35 is approximately 0.01 μm to 0.2 μm in order to obtain a desired amplitude and movement of electric charge necessary for driving the vibrating body 30 between the upper electrode portion 31 and the lower electrode 50. It is formed to a desired value within the range.

Then, the manufacturing method of the MEMS resonator 10 in Embodiment 1 is demonstrated with reference to drawings.
FIG. 2 is a cross-sectional view of the method for manufacturing the MEMS resonator 10 according to the first embodiment viewed along the AA cross section shown in FIG. 1A, and FIG. 3 is a cross-sectional view of the cross-sectional view taken along the BB cross section. First, in FIG. 2A, an insulating layer 21 made of SiO ₂ is formed on the surface of a semiconductor substrate 20 made of an Si layer, and an insulating layer 22 made of Si ₃ N ₄ is formed on the upper surface of the insulating layer 22, which will be described later. It is formed by the position and shape of the connecting portion.

FIG. 2B shows a process of forming an insulating layer 23 that becomes a sacrificial layer by element isolation by selective oxidation. In FIG. 2B, insulating layers 23 made of SiO ₂ as a selective oxidation layer are formed inside and outside the thickness direction of the semiconductor substrate 20 with the insulating layer 22 interposed therebetween. The insulating layer 23 is a selective oxidation layer as a device isolation layer, so-called LOCOS (Local oxidation of silicon). The insulating layer 23 is a part of the sacrificial layer 25 (see FIG. 2E).
At this time, a convex portion 20A is formed on the semiconductor substrate 20 below the insulating layer 22, and this convex portion 20A is a lower electrode region.

Next, as shown in FIG. 2C, the insulating layer 22 is removed by etching. Subsequently, an insulating layer 24 made of SiO ₂ is formed over the surface of the insulating layer 23 including the protrusions 20A (shown in FIG. 2D). The insulating layer 24A formed on the upper surface of the convex portion 20A is a void forming layer 24A that forms a first void 35 (see FIG. 2H) between the upper electrode portion 31 and the lower electrode 50.

Subsequently, a sacrificial layer 25 is formed by performing a gate oxidation step in the CMOS manufacturing process (see FIG. 2E). In the gate oxidation step, since the insulating layer 23 formed in advance and the insulating layer 24 formed on the upper surface thereof are both composed of SiO ₂ , a sacrificial layer 25 continuous with the gap forming layer 24A is formed. Subsequently, the lower electrode 50 is formed by a diffusion layer forming process.

FIG. 2F shows a diffusion layer forming step. In FIG. 2F, first, a mask resist 40 is formed on the upper surface of the sacrificial layer 25. Then, the lower electrode 50 made of a diffusion layer is formed by thermal diffusion or thermal diffusion by ion implantation of impurities. When the semiconductor substrate (Si layer) 20 is a p-type Si layer, the lower electrode (diffusion layer) 50 is an n ⁺ layer. The mask resist 40 is formed in a range excluding the periphery of the void forming layer 24A and the anchor portions 26 and 27 (see FIG. 3), and is formed in a thin section in the sacrificial layer 25 in the opening range of the mask resist 40. A diffusion layer is formed on the semiconductor substrate 20 below the gap forming layer 24A by self-alignment (self-alignment). No diffusion layer is formed in the thick sacrificial layer (the range of the insulating layer 23 shown in FIG. 2C). This diffusion layer is the lower electrode 50. Therefore, the lower electrode 50 is formed in substantially the same shape as the shape of the void forming layer 24A of the sacrificial layer 25.
After forming the lower electrode 50, the vibrating body 30 is formed.

FIG. 2G shows a process for forming the vibrating body 30. In FIG. 2G, a vibrating body 30 having a predetermined shape is formed of polysilicon on the upper surface of the sacrificial layer 25 by a CVD method (Chemical Vapor Deposition) or the like. The convex portion facing the lower electrode of the vibrating body 30 is the upper electrode portion 31, which is substantially the same as the planar shape of the lower electrode 50 and has planes parallel to each other. The upper electrode portion 31 of the vibrating body 30 is formed following the surface of the gap forming layer 24A of the sacrificial layer 25.
Accordingly, the shape of the opposing surfaces of the upper electrode portion 31 and the lower electrode 50 is substantially the same since it is regulated by the shape of the gap forming layer 24A.
Subsequently, the sacrificial layer 25 is removed.

  FIG. 2H shows a process of removing the sacrificial layer 25. In FIG. 2H, the sacrificial layer 25 is removed by wet etching or the like. Thus, the vibrating body 30 is formed like a both-end support beam supported by the anchor portions 33 and 34 (see FIG. 1C). At this time, the distance (interelectrode distance) of the gap 35 formed between the upper electrode portion 31 and the lower electrode 50 is formed to a desired value within a range of 0.01 μm to 0.2 μm. This gap (interelectrode distance) is obtained from the vibration frequency and amplitude of the vibrating body 30.

Then, the manufacturing method of the anchor part of the MEMS resonator which concerns on this embodiment is demonstrated with reference to drawings. The anchor portion is also formed by the manufacturing process described above (see FIG. 2).
FIG. 3 is a cross-sectional view showing the manufacturing process of the anchor portion. FIG. 3A shows a state in which the lower electrode 50 is formed through the steps shown in FIGS. 2A to 2E described above. Here, the anchor portions 26 and 27 are masked by the mask resist and the diffusion layer is not formed, and the insulating layer 24B remains. If the insulating layer 24B is present, the vibrator 30 made of polysilicon cannot be connected and formed, so that the insulating layer 24 formed on the upper surfaces of the anchor connecting portions 26 and 27 is removed by etching (not shown). Subsequently, the vibrating body 30 is formed.

  FIG. 3B shows a vibrating body forming step. The vibrating body 30 is formed in the same process as that shown in FIG. Here, since the insulating layer 24B is removed, the anchor portions 33 and 34 of the vibrating body 30 are in close contact with the anchor connecting portions 26 and 27 of the semiconductor substrate 20, respectively, so that the semiconductor substrate 20 and the vibrating body 30 are integrated. Formed with.

Subsequently, the sacrificial layer 25 is removed by wet etching.
FIG. 3C shows a state where the sacrificial layer 25 is removed. The vibrating body 30 formed in this way is a both-end support beam in which the anchor portions 33 and 34 are connected to the anchor connecting portions 26 and 27, and beams 32 </ b> A and 32 </ b> B as the vibrating portions of the electrode portion 31 and the vibrating body 30. And are formed.

  Therefore, in the first embodiment described above, the vibrating body 30 is formed of polysilicon, the lower electrode 50 is formed of a diffusion layer, and the gap between the upper electrode portion 31 and the lower electrode 50 is a sacrificial layer 25 formed by gate oxidation. Since the upper electrode portion 31 and the lower electrode 50 are both made of polysilicon, the gap between the upper electrode portion 31 and the lower electrode 50 is formed. The distance (distance between electrodes) can be formed with high accuracy of ± 5% or less of this distance, and a stable vibration mode and frequency characteristics can be obtained. Further, since the lower electrode 50 can be formed by a diffusion layer forming process such as thermal diffusion or ion implantation by a commonly used CMOS manufacturing process, the manufacturing process can be shortened as compared with the conventional example formed by polysilicon. .

  Moreover, since the 1st space | gap 35 with which the upper electrode part 31 and the lower electrode 50 have opposed can limit a management range, it can manage the distance between electrodes easily with high precision, Since the second gap 36 does not require the movable part of the vibrating body 30 to be in contact with the surface of the semiconductor substrate 20, the second gap 36 may be more loosely managed than the first gap, thereby improving the manufacturing yield. Can do.

Further, since the upper electrode portion 31 and the lower electrode 50 are formed following the shape of the gap forming layer 24A of the sacrificial layer 25, the opposing surfaces are formed in substantially the same shape. Since the movement of electric charges between the electrode 31 and the lower electrode 50 is difficult to disperse outside the range of the upper and lower electrodes, the vibrator can be driven efficiently.
(Embodiment 2)

Next, Embodiment 2 according to the present invention will be described with reference to the drawings. The second embodiment is characterized in that the configuration of the lower electrode is different from the first embodiment described above. Since the other configuration is the same as that of the first embodiment, description of the common part is omitted and the same reference numerals are given.
FIG. 4 shows a cross-sectional view of the MEMS resonator according to the second embodiment and the manufacturing method thereof. Note that the configuration of the anchor portion and the steps up to the formation of the sacrificial layer 25 are the same as those in the first embodiment (shown in FIGS. 3 and 2A to 2E), and thus description thereof is omitted.

  FIG. 4A shows a process of forming a mask resist 40 on the upper surface of the sacrificial layer 25. In FIG. 4A, after the sacrificial layer 25 is formed, a mask resist 40 is formed on the surface of the sacrificial layer 25 including the gap forming layer 24A. Openings 41 to 43 are opened in the mask resist 40. Subsequently, the process proceeds to the diffusion layer forming step.

  FIG. 4B shows a diffusion layer forming process. In the diffusion layer forming step, as in the first embodiment, a lower electrode made of a diffusion layer is formed by thermal diffusion or ion implantation. Since the openings 41 to 43 are formed in the mask resist 40, diffusion layers as shown in FIG. 4B, that is, lower electrodes 51 to 53 are formed only in the openings 41 to 43. . Subsequently, the vibrating body 30 is formed.

FIG. 4C shows the vibrating body forming step. The vibrating body 30 is formed of polysilicon by a CVD method in a predetermined shape on the upper surface of the sacrificial layer 25 as in the first embodiment (see FIG. 2G). The surface of the convex portion facing the lower electrode of the vibrating body 30 is the upper electrode portion 31, and has surfaces parallel to the peripheral plane 20 </ b> A including the lower electrode. The upper electrode portion 31 of the vibrating body 30 is formed following the surface of the gap forming layer 24A of the sacrificial layer 25.
Subsequently, the sacrificial layer 25 is removed by wet etching.

  FIG. 4D shows a state where the sacrificial layer 25 is removed and a MEMS resonator is formed. In FIG. 4, the lower electrode is divided into three parts, but the number of the lower electrodes is not limited and may be one, two, or three or more. Further, the lower electrodes 51, 52, 53 may be formed by parallel straight lines or may be formed concentrically.

Therefore, according to the above-described second embodiment, desired frequency characteristics can be easily obtained by selectively forming the number of lower electrodes and the interval and size of each divided lower electrode. Since the lower electrode is formed of the diffusion layer as described above, it can be formed by freely selecting the number of electrodes, their spacing, size, etc. by the CMOS manufacturing process.
(Embodiment 3)

Subsequently, Embodiment 3 according to the present invention will be described with reference to the drawings. The third embodiment is characterized in that the shape of the vibrating body 30 and the configuration of the corresponding lower electrode are different from the above-described second embodiment. The same reference numerals are given to the parts having the same shape as in the first and second embodiments including the anchor part.
FIG. 5 is a partial plan view showing the MEMS resonator 10 according to the third embodiment, and shows the relationship between the vibrating body 30 and the lower electrodes 54 to 56. In FIG. 5, three pairs of comb-like protrusions 30 </ b> A to 30 </ b> C protruding on both sides in the width direction are provided at the longitudinal center of the vibrating body 30. These protrusions 30A to 30C correspond to the upper electrode part 31 described in the first and second embodiments. Further, lower electrodes 54 to 56 corresponding to the shapes of the protrusions 30A to 30C of the semiconductor substrate 20 are formed by the diffusion layer forming step.

  Since the MEMS resonator 10 according to the third embodiment can be formed by the same manufacturing method as that of the second embodiment described above, it is not necessary to add a special process.

Although three pairs of comb-like protrusions are provided in FIG. 5, the number is not limited to three and any number can be selected and provided as appropriate. For example, two, four, or more may be used, and the size of the protrusion can be arbitrarily set.
Furthermore, in FIG. 5, the protrusions 30 </ b> A to 30 </ b> C are provided symmetrically in the width direction of the vibrating body 30. However, the protrusions 30 </ b> A to 30 </ b> C do not necessarily have to be symmetrical. Well, you may change the size.
Even if the protrusions are provided in this way, it is preferable that the lower electrode has a shape corresponding to the upper electrode part.

Therefore, according to the above-described third embodiment, the projecting portions 30A to 30C are provided on the vibrating body 30 and the lower electrodes 54 to 56 facing the projecting portions are provided. By appropriately setting the shape, it is possible to easily provide a MEMS resonator having different vibration modes and frequency characteristics.
(Embodiment 4)

Next, Embodiment 4 according to the present invention will be described with reference to the drawings. The fourth embodiment is characterized in that the beam portion 37 of the vibrating body 30 is formed on the same plane parallel to the surface of the semiconductor substrate.
FIG. 6 is a cross-sectional view showing the MEMS resonator 10 according to the fourth embodiment. In FIG. 6, the MEMS resonator 10 is formed by the same process as that of the first embodiment (see FIG. 2). However, the sacrificial layer 25 is formed over the range of the beam portion 37 of the vibrating body 30, and the vibrating body is formed. After forming 30, the sacrificial layer 25 is removed, so that the beam portion 37 is formed in parallel with the surface of the semiconductor substrate 20 and on the same plane. In order to set the gap 35 (distance between the electrodes) between the vibrating body 30 as the upper electrode portion and the lower electrode 50 to a predetermined distance, the upper surface of the sacrificial layer 25 is formed to a predetermined thickness such as CMP (Chemical and Mechanical Polishing). It may be polished by means.

In the MEMS resonator 10 according to the fourth embodiment, since the beam portion 37 as the vibrating portion of the vibrating body 30 has a simple both-end support beam shape, the vibration mode can be easily designed and the vibration mode is simplified. And stable frequency characteristics can be obtained. Moreover, since the shape of the vibrating body 30 is simple, it is easy to manufacture, and from these, manufacturing management can be facilitated, so that manufacturing efficiency can be increased.
(Embodiment 5)

Next, a fifth embodiment of the present invention will be described with reference to the drawings. The fifth embodiment is characterized in that the surface of the semiconductor substrate 20 facing the vibrating body 30 is formed on the same plane, and is a structure manufactured by the manufacturing method of the second embodiment. The description of the common parts is omitted, and the same reference numerals are given.
FIG. 7 is a cross-sectional view showing the MEMS resonator 10 according to the fifth embodiment. In FIG. 7, a lower electrode 50 serving as a diffusion layer is formed on the convex portion 20A between the insulating layers 23 formed by selective oxidation of the surface of the semiconductor substrate 20 by a diffusion layer forming step. The insulating layer 23 is formed at a position corresponding to the length of the beam portion 37 of the vibrating body 30 as compared to the first embodiment (see FIG. 2C). The formation position of the lower electrode 50 is determined by a mask resist (see FIG. 4A), and a diffusion layer (lower electrode 50) is formed only in the opening. The lower electrode 50 is formed in the same plane as the surface of the peripheral convex portion 20A.

The vibrating body 30 is manufactured by the same manufacturing process as that of the first embodiment (see FIGS. 2 and 3).
The beam portion 37 as the vibration portion is formed in the same plane, has a gap 35, and is parallel to the surface of the semiconductor substrate 20 (including the surface of the convex portion 20A and the lower electrode 50).

According to such a structure of the fifth embodiment, the beam portion 37 as the vibrating portion of the vibrating body 30 and the surface of the semiconductor substrate 20 facing the beam portion 37 are formed in the same plane and in parallel, respectively. Therefore, the distance between the electrodes is constant, and a more stable vibration mode can be obtained.
Moreover, if it is the same space, since the length of the beam part 37 can be set long with Embodiment 4, a frequency band can be made wide.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described first to fifth embodiments, structures and manufacturing methods that make use of the respective characteristics are shown, but it is possible to combine them.
For example, the structure in which the protrusions 30A to 30C of the third embodiment are provided can be applied to the fourth and fifth embodiments.

  Moreover, the structure which divides | segments the lower electrode in Embodiment 2 can be applied to Embodiment 5, and the effect which match | combined each characteristic can be acquired.

  In the above-described first to fifth embodiments, the vibrating body 30 has exemplified the double-end support beam structure. However, the shape of the vibration body is not limited to the double-end support beam structure, for example, even in a cantilever beam structure, The present invention can also be applied to a MEMS resonator having a vibrating body having a structure in which a beam extends radially from the (upper electrode).

Therefore, according to the present invention, a high-accuracy distance between the upper electrode portion and the lower electrode is formed in the CMOS manufacturing process without using a special manufacturing method for forming the MEMS resonator. There is an effect that it is possible to provide a MEMS resonator capable of obtaining a stable vibration mode and vibration frequency and a manufacturing method capable of shortening the process.
The MEMS resonator of the present invention can be employed in a MEMS oscillator, a MEMS resonator, or the like that is integrally formed on a semiconductor chip that incorporates a drive circuit or the like.

(A) is a top view which shows the MEMS resonator which concerns on Embodiment 1 of this invention, (b) is sectional drawing which shows an AA cross section, (c) is sectional drawing which shows a BB cross section. (A)-(h) is sectional drawing which shows the manufacturing method of the MEMS resonator which concerns on Embodiment 1 of this invention. Sectional drawing which shows the manufacturing method of the anchor part of the MEMS resonator which concerns on Embodiment 1 of this invention. Sectional drawing which shows the manufacturing method of the MEMS resonator which concerns on Embodiment 2 of this invention. The top view which shows the MEMS resonator which concerns on Embodiment 3 of this invention. Sectional drawing which shows the MEMS resonator which concerns on Embodiment 4 of this invention. Sectional drawing which shows the MEMS resonator which concerns on Embodiment 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... MEMS resonator, 20 ... Semiconductor substrate, 25 ... Sacrificial layer, 30 ... Vibrating body, 31 ... Upper electrode part, 35 ... 1st space | gap, 36 ... 2nd space | gap, 50 ... Lower electrode.

Claims (7)

Forming a first insulating layer on the surface of a semiconductor substrate having a lower electrode formation region by selective oxidation while avoiding the lower electrode formation region;
After the step of forming the first insulating layer, forming a second insulating layer having a thickness smaller than that of the first insulating layer on at least the lower electrode formation region;
After the step of forming the second insulating layer, forming a lower electrode made of a diffusion layer in the lower electrode formation region;
Forming an upper electrode on the second insulating layer;
Removing the first insulating layer and the second insulating layer;
A method for producing a MEMS resonator, comprising: In the manufacturing method of the MEMS resonator of Claim 1,
A method of manufacturing a MEMS resonator, further comprising a step of forming a sacrificial layer by continuously forming the first insulating layer and the second insulating layer by a gate oxidation step. In the manufacturing method of the MEMS resonator of Claim 1 or Claim 2,
The method of manufacturing a MEMS resonator, wherein the shapes of the opposing surfaces of the upper electrode and the lower electrode are substantially the same. In the manufacturing method of the MEMS resonator as described in any one of Claims 1 thru | or 3,
A method of manufacturing a MEMS resonator, comprising forming a beam portion integrally with the upper electrode on the first insulating layer when forming the upper electrode. In the manufacturing method of the MEMS resonator as described in any one of Claim 2 thru | or 4,
A method of manufacturing a MEMS resonator, further comprising a step of flattening an upper surface of the sacrificial layer by CMP. A semiconductor substrate;
An upper electrode formed through the semiconductor substrate and a first gap;
A beam portion formed through the semiconductor substrate and a second gap and formed integrally with the upper electrode;
A lower electrode made of a diffusion layer, formed on the semiconductor substrate so as to face the upper electrode;
Including
The distance of the first gap between the lower electrode and the upper electrode is smaller than the distance of the second gap between the semiconductor substrate and the beam portion,
The MEMS resonator is characterized in that the shapes of the opposing surfaces of the upper electrode and the lower electrode are substantially the same. The MEMS resonator according to claim 6, wherein
The surface of the upper electrode and the surface of the beam are the same plane parallel to the surface of the semiconductor substrate.

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