JP4994096B2 - Semiconductor device manufacturing method and semiconductor device using the same - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device and a semiconductor device using the same, and more particularly to a microdevice manufactured using MEMS (Micro Electro Mechanical Systems) technology and a method for manufacturing the same, and more particularly, an RF-MEMS having an electrode and a gap. The present invention relates to the formation of a resonator and a protruding structure portion of an RF-MEMS filter.

  In a current MEMS device, a structure in which an electrode is formed with a gap sandwiched between microstructures is applied in a wide range of device fields such as sensors, actuators, switches, resonators, and filters having capacitive coupling. When two or more electrodes are arranged on one protruding structure in such a device, a parallel electrode structure in which electrodes are arranged in a plane with respect to the substrate and a plane perpendicular to the substrate or inclined There are two types of side electrode structures in which electrodes are arranged on the surface. In addition, the manufacturing method of the two protruding structures is different, and in the case of the parallel electrode structure, at least two film forming steps are required. Therefore, there is an advantage that the manufacturing method is also simple.

  However, in the case of the side electrode structure, a manufacturing method is required in which the conductive film (electrode film) formed in one step is separated into two patterns to form electrodes. For example, in the method of manufacturing an electron gun proposed by Hashiguchi and Hara, the conductive film is pattern-separated by an etch-back process to realize the formation of two electrodes (Patent Document 1). In this method, an upper portion of a resist covering a conductive film deposited on a structure having an inclined surface is etched, and a desired region of the conductive film is etched from above by using the resist as a mask. The conductive film can be separated at the portion. In this case, in order to pattern other regions such as the other end portion, it is necessary to etch only a necessary portion. For this purpose, it is necessary to protect a region other than the region to be etched with a mask.

  Therefore, a method is used in which a resist is applied to the entire surface, resist etch back is performed, a portion to be etched is exposed from the resist, and then an electrode film in that region is etched to form an electrode. This manufacturing method is shown in FIG.

In this method, as shown in FIG. 6 (a), a pattern having a triangular cross section surrounded by the (111) plane is formed by using anisotropic etching of silicon, the surface of the silicon substrate 100 is thermally oxidized, An insulating film 101 made of a silicon oxide film is formed.
Then, as shown in FIG. 6B, a metal film 102 such as a tungsten film is further deposited thereon. Thereafter, a resist R1 is applied so that the film thickness becomes thicker than the height of the convex portion having a triangular cross section of the silicon substrate 100 (FIG. 6C).
Then, as shown in FIG. 6D, the resist R1 is etched back from above, and the protruding portion of the silicon substrate 100 covered with the insulating film 102 made of a silicon oxide film is exposed.

  In this state, by using the resist R1 as a mask and etching the metal film 102 as shown in FIG. 6E, the metal film 102 on the protruding portion is separated at the upper end by the first etching, The electrodes are formed separately.

Further, as shown in FIG. 6 (f), the electrode mask is patterned by subsequent photolithography to form a resist pattern R2, and as shown in FIG. 6 (g), the second etching of the metal film is performed. The other end is defined and an electrode is formed. Finally, as shown in FIG. 6H, the insulating film 101 is locally removed to expose the tip of the electron gun emitting portion, thereby completing the MOS device structure having the side electrode pattern.
JP-A-6-310029

  However, the process of etching back a sacrificial layer such as a resist in the manufacturing method for forming these conventional electrodes requires a high-precision etching control technique, and has a problem that sufficient pattern accuracy cannot be obtained. For example, it is extremely difficult to form a sacrificial layer mask by exposing the apex to a projecting structure having an inclination. In the resist etch-back method, apex patterning is performed by controlling the etching rate, so that it is necessary to have precise functions such as precise time management and an etching endpoint detection function in the apparatus.

In addition, since the conventional manufacturing method using the etch back process requires at least two etching processes for patterning the apex and the electrode, the manufacturing process increases and the cost increases.
The present invention has been made in view of the above circumstances, and an object thereof is to realize highly accurate and reliable pattern formation without using precise time management and a special apparatus.

That is, the method of the present invention includes a step of forming a protruding structure portion having an inclined surface on a semiconductor substrate surface, a step of forming an insulating film on the surface of the protruding structure portion, and a conductive film on the upper surface of the insulating film. A step of applying a resist so that at least a top portion of the protruding structure portion is exposed on the surface on which the conductive film is formed, and a top portion of the protruding structure portion exposed from the resist. It includes a step of electrically separating the conductive film by etching the conductive film and a step of removing the resist.
With this configuration, the resist is applied to the uneven surface, and the conductive film is separated by etching in a state where a part of the convex portion is exposed. The heights of the conductive films are the same.

According to the present invention, in the method of manufacturing a semiconductor device, the separating step includes a step of patterning the resist by photolithography, a region exposed from the resist in the patterning step, and a top portion of the protruding structure portion. Etching the conductive film.
With this configuration, efficient patterning of the conductive film can be realized at a time.

According to the present invention, in the method of manufacturing a semiconductor device, the semiconductor substrate is an SOI substrate having a single crystal silicon layer on a surface, and the step of forming the protruding structure portion includes (111) plane by anisotropic etching. Is formed so as to leave as an inclined surface.
According to this configuration, by using anisotropic etching that slows the etching rate of the (111) plane, high-efficiency patterning can be performed with high reproducibility using the etching selectivity on the (111) plane. Is possible.

According to the present invention, in the method of manufacturing a semiconductor device, the method includes a step of forming a buried insulating film (BOX layer) prior to the formation of the protruding structure portion, and the resist is removed after the step of etching the conductive film. And a step of removing the insulating film between the electrode and the protruding structure portion and the buried insulating film formed under the protruding structure portion.
With this configuration, it is possible to realize a hollow structure very efficiently by removing the buried insulating film.

According to the present invention, in the method of manufacturing a semiconductor device, the step of forming the buried insulating film includes a step of digging a deep groove from the back surface of the semiconductor substrate, and the insulating film positioned between the electrode and the protruding structure portion. And a step of removing the second insulating film when the first insulating film is an insulating film formed under the protruding structure portion.
With this configuration, it is possible to realize a hollow structure extremely efficiently by removing the first and second insulating films. In addition, by forming the first and second insulating films with the same material, the first and second insulating films can be simultaneously etched. The first and second insulating films are not necessarily made of the same material as long as they can be etched under the same etching conditions.

According to the present invention, in the method of manufacturing a semiconductor device, a buried insulating film (BOX layer) formed to have a step and become higher in a lower layer of the projecting structure portion forming region prior to the formation of the projecting structure portion. Forming a step.
With this configuration, it is possible to increase the thickness of the resist for projecting the apex of the projecting structure portion, and it is possible to improve uniformity and selectivity.

The present invention also includes the method for manufacturing a semiconductor device, wherein the step of forming the first insulating film is a step of forming an oxide film by oxidation of the semiconductor substrate.
With this configuration, it is possible to efficiently form an oxide film having a highly accurate film thickness.

According to the present invention, in the method for manufacturing a semiconductor device, the step of forming the first insulating film includes forming an oxide film having a thickness of several nm by chemically reacting the surface of the semiconductor substrate by RCA or SPM cleaning. It is a process.
With this configuration, it becomes possible to easily and efficiently form a thin oxide film by using the oxide film obtained in the cleaning process as an insulating film. RCA is a cleaning technology developed by RCA. SC-1 cleaning (Standard Clean 1) consisting of aqueous ammonia and hydrogen peroxide for particle removal, and hydrochloric acid and excess for the purpose of metal impurity removal. This is a cleaning technique combined with SC-2 cleaning (Standard Clean 2) composed of hydrogen oxide water. SPM cleaning is a cleaning technique for removing organic substances and performing treatment at a high temperature of 100 ° C. or higher by adding hydrogen peroxide to concentrated sulfuric acid.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: a vibrator formed so as to be capable of mechanical vibration; and an electrode disposed at a predetermined interval with respect to the vibrator; The vibrator constitutes a MEMS resonator including the protruding structure portion.
With this configuration, it is possible to form a fine and reliable beam-like vibrator.

According to the present invention, in the method for manufacturing a semiconductor device, the vibrator includes a vibrator having a triangular cross section.
With this configuration, for example, by using a triangle with a (111) plane as one side, a highly accurate pattern can be easily formed with good reproducibility.

  The present invention also includes the method for manufacturing a semiconductor device, wherein the electrode is formed with a step.

That is, the manufacturing method of the present invention includes a step of forming an insulating film on a protruding structure portion having a certain inclination, a step of depositing a conductive film on the insulating film, and a step of forming the protruding structure portion on the conductive film. Supplying a resist so as to be thinner than the height, exposing the apex of the protruding structure by spin coating of the resist, patterning the mask of the conductive film by exposing and developing the resist, and patterning It is a manufacturing method for forming an electrode on a protruding structure portion having a gap, which includes a step of etching a conductive film and an exposed vertex, and a step of removing the insulating film.
With this configuration, it is possible to form a gap with a high degree of dimensional accuracy by utilizing the reproducibility of the film thickness by spin coating, and it is possible to form a gap with high accuracy and high reliability.

  According to the method of the present invention, a resist device that is difficult to control is not required, and a MEMS device that completes the formation of apexes and electrodes, which was impossible in the past, by a single etching process is manufactured. be able to. As a result, a manufacturing method capable of forming apexes and a large number of electrodes in a simple and accurate manner is realized, and can be applied to various MEMS devices that form electrodes through gaps.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a manufacturing method and a MEM formed thereby according to Embodiment 1 of the present invention.
It is sectional drawing of S device.
The electrode forming method on the micro-projection structure of the present invention is mainly applicable to the production of a MEMS resonator. In the electrode forming method of the present embodiment, first, as shown in FIG. 1A, the single crystal silicon layer of the SOI substrate is anisotropically etched to form the triangular cross-section beam 1 and the surface is thermally oxidized. Thus, a thin insulating film 10 is formed. When an SOI substrate is used, since the BOX layer 2 is formed of an oxide film, it is desirable to use a silicon oxide film made of the same material as the insulating film 10. The insulating film 10 forms a narrow gap of the MEMS resonator, and uses an LPCVD oxide film or a thermal oxide film that needs a film thickness of several tens to several hundreds of nanometers and can control the film thickness with high precision. Is desirable.

  Thus, the structure of the resonator can be obtained by forming the triangular cross-section beam 1 by crystal anisotropic etching using a tetramethylammonium hydroxide (TMAH) aqueous solution. At this time, for example, by performing anisotropic etching using an SOI substrate having a silicon layer thickness of 1.5 μm, the silicon is etched along the (111) side surface, and the triangular cross-section beam is in contact with the silicon surface. Etching is performed at an angle of 54.7 °. Thus, since the beam width (2.1 μm) is determined by the thickness of the silicon layer of the substrate to be manufactured, the beam-type vibrator can be formed with high accuracy.

  In this way, after the beam-type vibrator having the triangular cross-section beam is formed, an oxide film for forming a gap is formed. Since this gap width leads to the RF characteristics of the resonator, the oxide film used here is desirably a uniform and thin film. For example, when a thermal oxide film is used as the sacrificial layer, an oxide film having a thickness of 50 nm is grown on the side surface of the triangular cross section beam in an oxidation furnace. Thereafter, doped polysilicon (conductive film) to be an electrode film is deposited by LPCVD.

  In the manufacturing method of the present invention, the silicon surface of the triangular cross section beam 1 is formed by a substrate cleaning (RCA, SPM, etc.) processing step required before the step of FIG. An oxide film of several nm formed by a chemical reaction may be used as the insulating film 10.

Next, the process of exposing the apex of the triangular cross-section beam and the process of forming the mask pattern of the electrode are performed by a photolithography process, the details of which will be described below.
A positive resist having a trade name of Shipley 1805 (registered trademark) is used as the resist, and coating is performed with a spin coater at a rotational speed of 4000 rpm for 30 seconds. Thereafter, baking is performed for about 2 minutes on a hot plate at 90 ° C., and the resist is coated while maintaining a uniform thickness (410 nm) so that the entire surface of the substrate has a flat surface. Since the height of the triangular cross-section beam is determined by the thickness (1500 nm) of the silicon layer of the SOI substrate, there is little variation, and this makes it possible to accurately expose the apex (1090 nm) of the beam.

That is, first, as shown in FIG. 1B, the conductive film 11 is uniformly formed using a CVD method or the like, and the resist 12 is formed as shown in FIG. It is desirable to use polysilicon as the conductive film 11. FIG. 1C shows a state in which a resist 12 is applied on the conductive film and spin-coated. Here, the top surface of the conductive film 11 is exposed. That is, the spinner rotation speed and the resist viscosity are determined so that the resist coating thickness is thinner than the height of the triangular cross section beam 1, and the film thickness of the resist 12 is determined by spin coating. In this case, although depending on the exposed region, when the film thickness of the resist 12 is mainly set to 1/3 to 1/4 of the height of the triangular cross section beam 1, the vertex 13 is exposed after spin coating. Thereafter, the process returns to the normal photolithographic process of the conductive film 11, and after exposure and development of the resist, patterning of the electrode mask is performed.
Then, as shown in FIG. 1D, photolithography is performed to pattern the conductive film 11.

  In this manner, after the apex is exposed by spin coating, the resist is exposed using a photomask, and then the resist is developed, whereby a mask pattern for forming an electrode pattern is formed. The state after this process is shown by SEM photographs in FIGS. 2 (a) and 2 (b) show an overall view and an enlarged view of a triangular cross-section beam having a length of 20 μm and a width of 2 μm, respectively, and from this photograph, the apex of the beam is accurately exposed, and for forming a desired electrode pattern It can be confirmed that a mask pattern is formed.

Next, as shown in FIG. 1E, the protruding apex 13 and the patterned conductive film 11 are simultaneously patterned by one etching process. Here, since the etching process needs to use etching conditions with good selectivity of the polysilicon film mainly serving as the conductive film 11 with respect to the oxide film serving as the insulating film 10, SF ₆ gas is used here. The dry etching used is suitable for this manufacturing method.

  As described above, the exposed apex and the electrode are dry-etched by the RIE apparatus, and after the etching, the resist is completely removed from the substrate.

  Next, as shown in FIG. 1 (f), the insulating film 10 and the BOX layer 2 are removed to leave the portion serving as a support portion, the triangular cross-section beam 1 is opened, and an electrode having a narrow gap protrudes from the structure portion. The aerial projecting structure portion arranged on the side surface is completed.

  In the last step, it is necessary to form a gap and release the triangular cross-section beam from the substrate. Therefore, using hydrofluoric acid, etc., the oxide film between the electrode and the beam and the oxide film present in the lower layer of the beam are removed. The beam-type resonator is manufactured by removing. The manufactured resonator is shown in FIG.

  FIG. 3 shows a resonator structure in which electrodes are added to both sides of a triangular cross-section beam having a length of 20 μm and a width of 2 μm. From this photograph, it is confirmed that a narrow gap of 50 nm is formed between the electrode and the beam, and the vertex of the silicon beam is completely exposed.

  This makes it possible to produce an electrode pattern with high accuracy with a smaller number of steps as compared with a conventional electrode forming method using an etch-back process.

(Embodiment 2)
FIG. 4 is a cross-sectional view of the manufacturing method and the MEMS device formed thereby according to the second embodiment of the present invention. The manufacturing method of the present invention is characterized in that an etch-back process is not required, but a groove 17 is dug in the BOX layer, a step is provided, and the height of the triangular cross-section beam 15 formed by the protruding structure portion is 1 μm. Therefore, in order to expose the apex of a desired portion, it is necessary to form the resist 19 to be applied in a later process in a very thin thin film. If the thickness of the resist 19 is about 1/4 of the height of the triangular cross-section beam 19, the resist 19 is coated with a thin film of 250 nm or less. With this thickness, the uniformity of the resist 19 and the selectivity with respect to the electrode to be etched can be obtained. It may be impossible to remove.

  Therefore, the method of the present invention is characterized in that a groove 17 is dug in the BOX layer to provide a step. This makes it possible to increase the thickness of the resist 19 for projecting the apex of the nano-projection structure portion 15, thereby improving uniformity and selectivity, and eliminates the need to use a special thin film resist.

The manufacturing method of the nanoprojection structure part which forms the electrode of this invention is mainly applied to preparation of a MEMS resonator. First, the monocrystalline silicon layer on the surface of the SOI substrate 100 on which the BOX layer 2, the silicon support substrate 3, and the back side protective film 4 shown in FIG. 4A are deposited is patterned by anisotropic etching, and the width is 1 μm or less. And an insulating film (silicon oxide film) 16 is formed thereon by surface thermal oxidation.

  Next, as shown in FIG. 4B, the BOX layer 2 is etched using the insulating film 16 as a mask to form a groove 17. The depth is adjusted by the thickness of the resist in a later step, but etching is performed in the range of several hundred nm to several μm. After the groove 17 is formed as shown in FIG. 4B, the conductive film 18 is formed on the BOX layer 2 and the triangular cross-section beam 15 composed of the protruding structure as shown in FIG. 4C. Form a film.

  Then, as shown in FIG. 4 (d), a resist 19 is applied, and a mask between the apex and the electrode is patterned. First, a resist 19 is applied on the conductive film 18, and the thickness is set to be equal to or greater than the depth of the groove 17 and equal to or less than the height of the triangular cross-section beam 15 formed by the protruding structure portion. . Here, as the groove 17 is formed, the resist film thickness can be increased. Thus, after the resist application, with the apex of the triangular cross section beam 15 constituted by the protruding structure portion protruding, the electrode alignment, exposure, and development are performed to form an electrode mask pattern.

  Next, the pattern of the conductive film at the apex 20 and the conductive film at the periphery 21 shown in FIG. 4E is formed. Here, both etchings are completed by one etching process. . Finally, in FIG. 4F, the BOX layer 2 and the insulating film 16 are removed, and the opening 22 and the gap 23 of the BOX layer are formed, thereby completing the hollow structure of the MEMS resonator.

(Embodiment 3)
FIG. 5 is a cross-sectional view of the manufacturing method and the MEMS device formed thereby according to Embodiment 3 of the present invention.
The manufacturing method for forming the electrode of the present invention secures a place where the resist flows on the top surface by providing one or more small grooves 28 on the top of the projecting structure 51 having a square cross section. The upper surface portion is completely exposed.

In this embodiment, first, an oxide film 26 of 1 μm or more is formed on the single crystal silicon substrate 25 shown in FIG. Next, in FIG. 5B, a device forming layer 27 made of an amorphous silicon layer for forming a movable structure is formed, and in FIG. 5C, the device forming layer 27 is patterned to form a square protruding structure portion. 50 and 51 are formed.

  Next, as shown in FIG. 5D, a second patterning is performed on the device formation layer by photolithography to form a resist pattern, and etching is performed using the resist pattern as a mask to form the square projecting structure 51. A groove 28 is formed. In this method, as the role of the groove 28, for example, when the upper surface of the projecting structure portion has a parallel surface width of several μm or more as in the case of the square projecting structure portion 51, a resist is applied and the apex is formed This is to prevent the resist from remaining on the upper surface of the projecting structure portion 51 and the desired upper surface portion from being exposed.

  On the other hand, in the embodiment of the present invention, after the groove 28 is formed, the surface is thermally oxidized as shown in FIG. A conductive film 30 is deposited thereon (FIG. 5 (f)).

Further, as shown in FIG. 5G, the mask is formed by patterning the device forming layer for the third time. Here again, the thickness of the resist 31 is made thinner than the height of the device forming layer. Apply to substrate. At this time, the resist adhering to the upper surface of the square projecting structure 51 stays in the groove 28 formed in FIG.
Is protruded only at a desired region.

  As shown in FIG. 5H, the exposed conductive film is etched. In this case, the upper surface portions of the square protruding structure portions 50 and 51 are simultaneously etched in one step. After the etching, the electrode 33 is formed in the groove 28 by pattern separation.

Next, in FIG. 5I, the deep groove 34 is formed by etching from the back side surface of the silicon substrate 25. Thereafter, the protruding structure part is opened (formation of a gap for opening the structure part) shown in FIG.
Here, for example, by performing wet etching, etching can be performed from both surfaces of the substrate 25, so that the oxide film 26 and the insulating film 29 can be simultaneously removed. Further, when the insulating film 29 is removed in this step, the electrode 33 formed in the groove 28 is opened, so that no electrode remains between the grooves 28 of the protruding structure portion 51. After the etching, the formation of the gap 35 and the groove 36 for opening the structure portion are completed, and the hollow structure of the square projecting structure portions 50 and 51 having electrodes is produced.

  In the above embodiment, the pattern separation of the conductive film has been described. However, the present invention can be applied not only to the conductive film but also to the pattern separation of thin films such as an insulating film and other functional films.

  The manufacturing method for forming an electrode according to the present invention eliminates the resist etch-back process, which is difficult to control, and can easily and accurately separate the convex apex and form the electrode at the same time. It is useful as a MEMS resonator in the field.

Sectional explanatory drawing which shows the manufacturing process of the MEMS resonator in Embodiment 1 of this invention The figure which shows the triangular cross-section beam of the MEMS resonator in Embodiment 1 of this invention The figure which shows the MEMS resonator in Embodiment 1 of this invention. Cross-sectional explanatory drawing which shows the manufacturing process of the nanosized MEMS resonator in Embodiment 2 of this invention Cross-sectional explanatory drawing which shows the manufacturing process of the MEMS device in Embodiment 3 of this invention Cross-sectional explanatory drawing showing the manufacturing process of an electron gun manufactured in a conventional etch-back process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Triangular cross-section beam 2 BOX layer 3 Support substrate 4 Protective film 10, 16, 29 Insulating film 11, 18, 30 Conductive film 12, 19, 31 Resist 15 Triangular cross-section beam (single crystal silicon layer)
13, 20 Vertex 17 BOX layer groove 21 Electrode pattern 22, 36 Release of protruding structure (part)
23, 35 Gap 25 Silicon substrate 26 Oxide film 27 Device formation layer 28 Groove 32 Exposed upper surface portion 33 Electrode 34 formed in groove Deep groove

Claims (11)

Forming a protruding structure having an inclined surface on the surface of the semiconductor substrate ;
Forming an insulating film on the surface of the protruding structure;
Forming a conductive film so as to cover the upper surface of the insulating film;
Applying a resist so that at least the top of the conductive film of the protruding structure portion is exposed on the surface on which the conductive film is formed;
Electrically isolating the conductive film by etching the conductive film on the top of the protruding structure portion exposed from the resist;
And a step of removing the resist. A method of manufacturing a semiconductor device according to claim 1 ,
The separating step includes
Patterning the resist by photolithography,
A method of manufacturing a semiconductor device, comprising: etching the conductive film on the top of the projecting structure portion and the region exposed from the resist in the patterning step of the conductive film. A method of manufacturing a semiconductor device according to claim 1 or 2 ,
The semiconductor substrate is an SOI substrate having a single crystal silicon layer on the surface,
The step of forming the protruding structure portion includes a step of forming the (111) plane as an inclined surface by anisotropic etching. A method of manufacturing a semiconductor device according to any one of claims 1 to 3,
A step of forming a buried insulating film (BOX layer) prior to the formation of the protruding structure portion;
After the step of removing the resist,
A method of manufacturing a semiconductor device, comprising: removing an insulating film between the conductive film and the protruding structure portion and the buried insulating film formed below the protruding structure portion. A method of manufacturing a semiconductor device according to claim 4 ,
A method of manufacturing a semiconductor device including a step of forming a buried insulating film (BOX layer) formed so as to have a level difference in a lower layer of the protruding structure portion forming region before forming the protruding structure portion. The method for manufacturing a semiconductor device according to claim 4, wherein the step of forming the buried insulating film comprises:
Digging deep grooves from the back surface of the semiconductor substrate;
Removing the first insulating film, which is the insulating film located between the conductive film and the protruding structure portion, and the second insulating film, which is an insulating film formed under the protruding structure portion A method of manufacturing a semiconductor device including: A method of manufacturing a semiconductor device according to any one of claims 1 to 6,
The method of manufacturing a semiconductor device, wherein the step of forming the first insulating film is a step of forming an oxide film by oxidizing the semiconductor substrate. A method of manufacturing a semiconductor device according to claim 7 ,
The step of forming the first insulating film is a method of manufacturing a semiconductor device, which is a step of forming an oxide film having a thickness of several nm by chemically reacting the surface of the semiconductor substrate by cleaning the substrate. Is formed by using a method of manufacturing a semiconductor device according to any one of claims 1 to 8,
A vibrator formed so as to be capable of mechanical vibration and an electrode disposed at a predetermined interval with respect to the vibrator;
A semiconductor device in which the vibrator constitutes a MEMS resonator including the protruding structure. The semiconductor device according to claim 9 ,
The vibrator is a semiconductor device having a triangular cross section. The semiconductor device according to claim 9 ,
A semiconductor device in which the electrode is formed with a step.