JPH06347471A - Dynamic sensor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a sensor excellent in detection sensitivity and strength by forming the base section of a detecting section roughly into an octagon in cross section, and concurrently, covering three surfaces composed of one surface where the detection element of the detecting beam section is formed and of two surface adjacent to the aforesaid one surface with a protective film. CONSTITUTION:A silicon nitride film 102 is so patterned that an overlapping section with a detecting beam section is formed in a base section 101 processed by etching. The film-forming and patterning of a lower electrode 103, a piezo-electric thin film 104 and an upper electrode 105 are carried out. The base board section 101 of the detecting beam section is roughly formed into an octagon shape in cross section, and three surfaces composed of one surface where the detection element of the detecting beam section is formed, and of two surface adjacent to the aforesaid one surface, are covered with a protective film 106. Covering as mentioned above prevents the electrodes 103 and 105 and the piezoelectric thin film 104 from being damaged by etching solution, the side surface of the detecting beam section can be formed roughly into an upright shape by etching, and concurrently, deterioration due to moisture and the like can by prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical sensor such as an angular velocity sensor and an acceleration sensor and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a semiconductor angular velocity sensor, a semiconductor acceleration sensor, and the like, which are manufactured by etching a semiconductor such as silicon, have been proposed. FIG. 6 is a diagram showing an example of a detection unit that detects the angular velocity or acceleration of these sensors, and FIG. 6A is a top view of the detection unit.
(B) is sectional drawing in the AA 'surface. 60 in the figure
Reference numeral 1 is a silicon substrate, 602 is a weight portion, and 603 is a detection beam portion. The weight portion 602 and the detection beam portion 603 are manufactured by etching the silicon substrate 601. Further, reference numeral 604 is a detection element, which is composed of a lower electrode 606, a piezoelectric thin film 607, and an upper electrode 608.
Reference numeral 605 is an insulating film. The detection element 604 is formed outside or inside the neutral surface of the detection beam portion 603, respectively. In the weight portion 602 and the detection beam portion 603,
When a force in the direction of the arrow F shown in the figure is applied, one piezoelectric thin film on the detection beam portion 603 expands and the other piezoelectric thin film contracts. Therefore, from the output potential difference between these two piezoelectric thin films, The applied external force can be calculated.

When detecting the angular velocity, the weight portion 602 is used.
Is oscillated at a constant frequency in the direction of arrow X shown in FIG. When an angular velocity around the detection shaft 609 is applied to the vibrating weight portion 602, the weight portion 602 receives a Coriolis force in the direction of arrow F, and the detection beam portion 603 is flexibly deformed in the same direction. Since the Coriolis force is proportional to the angular velocity, the detection beam portion 60
From the deformation amount of 3, the applied angular velocity can be detected. Since the force generated in the arrow F direction is proportional to the acceleration applied in the arrow F direction, the applied acceleration can be detected from the deformation amount of the detection beam portion 603.

In the semiconductor angular velocity sensor and the semiconductor acceleration sensor as described above, the beam portion for detection has a shape that is easily deformed in the direction of arrow F and has a sufficient strength in order to improve the detection sensitivity. Don't Therefore, in consideration of the balance between the amount of deformation and the strength, it is desirable that the side surface of the detection beam portion 603 is vertical to the surface on which the detection element is formed. For that purpose, it is necessary to etch the silicon substrate 601 so that the etching cross section of the flat substrate becomes vertical.

On the other hand, a method shown in FIG. 7 has been proposed as a method for etching a silicon substrate having a thickness of several hundreds of μm so that the etching cross section has a vertical shape. In the figure, 701 is a (100) oriented silicon substrate, and 702 is a silicon nitride film. In this method, first, the silicon nitride films 702 formed on both sides of the silicon substrate 701 are removed by etching in a predetermined pattern (FIG. 7B), and this is etched from both sides using a potassium hydroxide solution. As a result, a silicon (111) plane 703 appears due to anisotropic etching of silicon. After being removed from both sides (FIG. 7C), when etching is further performed, the etching progresses as shown in FIG. 7D, and finally the side face as shown in FIG. 7E has a vertical shape. An etched surface is obtained.

[0006]

However, when the detection beam portion is manufactured by the above-mentioned conventional method, there are the following problems. First, in a method of forming a detection element after forming a detection beam portion by etching a silicon substrate, it is very difficult to uniformly apply a resist on the detection beam portion, and an electrode formed by an ordinary photolithography process is used. Also, it is difficult to pattern the piezoelectric thin film. Second, in the method of forming the detection beam by etching the silicon after forming the detection element, the electrodes and the piezoelectric thin film are exposed to the potassium hydroxide solution, so that the piezoelectric thin film is dissolved and the characteristics are deteriorated. Occurs. Further, in the above-mentioned conventional example, since the side surface of the piezoelectric thin film for detection is exposed, there is a problem that the piezoelectric characteristics are deteriorated due to the influence of moisture in the air, and the detection characteristics vary and deteriorate. It was

As a method for solving the above problems, a method of forming a detection element, then forming a protective film on the detection element, and then etching silicon to form a detection beam portion can be considered. However, this method also has the following problems. First, in order to increase the detection sensitivity, it is desirable to form the detection element as outside of the detection beam as possible, but if you try to cover the side surface of the detection element with a protective film,
Since side etching of the protective film occurs, the detection element has to be formed slightly closer to the center of the detection beam portion, and the detection sensitivity decreases. Secondly, when a protective film is formed on the detection element, the step coverage of the protective film is poor, and the potassium hydroxide solution may infiltrate from the step portion during etching to deteriorate the electrode and the piezoelectric thin film. is there. Therefore, an object of the present invention is to solve the above problems of the prior art, and to provide a dynamic sensor having excellent detection sensitivity and strength and excellent stability, and a manufacturing method thereof.

[0008]

The above object can be achieved by the present invention described below. That is, according to the present invention, a flat plate-shaped substrate is subjected to an etching process to integrally form a detection beam portion and a weight portion, and the deformation amount of the weight portion that causes the detection beam portion to be deformed by an external force is detected. In the dynamic sensor provided with the detection element of No. 2, the cross-sectional shape of the substrate portion of the detection beam portion is substantially octagonal, and the surface of the detection beam portion on which the detection element is formed and the surface adjacent to the surface The mechanical sensor is characterized in that three surfaces are covered with a protective film.

[0009]

As a result of improving the detection beam portion of the mechanical sensor, the present inventors cover the surface and the side surface of the detection element with a protective film, so that the electrode and the piezoelectric thin film are damaged by the etching solution. And the side surface of the beam portion for detection can be etched into a substantially vertical shape.
The present invention has been made based on the finding that the detection element can be formed just outside the detection beam portion, so that a mechanical sensor having excellent detection sensitivity and strength can be manufactured. . Further, the mechanical sensor of the present invention is excellent in stability because the characteristics of the detection element are not deteriorated by moisture in the air.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to preferred embodiments. FIG. 1 is a cross-sectional view of a detection beam portion of a mechanical sensor of the present invention. In the figure, 101 is a silicon substrate, 102 is a silicon nitride film, 103 is a lower electrode, 10
Reference numeral 4 is a piezoelectric thin film, 105 is an upper electrode, 106 is a protective film, and the protective film 106 is formed so as to cover part of the upper surface and side surfaces of the detection beam portion. Further, as the material for forming the lower electrode 103 and the upper electrode 105, gold, platinum, aluminum or the like can be used. As a material for forming the piezoelectric thin film 104, zinc oxide (ZnO), lead zirconate titanate (PZT), lead titanate (PbTiO ₃ ) or the like can be used. Further, as a material for forming the protective film 106, a silicon nitride film, a silicon oxide film or the like can be used.

Next, a method of manufacturing the dynamic sensor of the present invention will be described with reference to FIG. In the figure, 201 is a silicon substrate having a (100) plane orientation, and 202 is a silicon nitride film (FIG. 2A). First, the silicon nitride film 202 is patterned and etched to form an opening 207 for forming the weight portion and the detection beam portion 208 (FIG. 2 (b)), and then silicon is used in a potassium hydroxide solution. Board 20
1 is shallowly etched to obtain the state shown in FIG. In the figure, 209 is a silicon (111) plane. Next, FIG.
As shown in (d), the lower electrode 203 and the piezoelectric thin film 204
Then, film formation and patterning of the upper electrode 205 are performed.
The lower electrode 203 and the upper electrode 205 can be formed by a sputtering method or a vapor deposition method. The piezoelectric thin film 204 can be formed by a sputtering method, a vapor deposition method, a sol-gel method, or the like.

Next, as shown in FIG. 2E, the protective film 2
06 is deposited. Although a silicon nitride film and a silicon oxide film can be used as the protective film 206, in order to prevent deterioration of the characteristics of the piezoelectric thin film 204, a low temperature (Zn
It is necessary to form the film at 250 ° C. or lower for O and 400 ° C. or lower for PZT. Therefore, when the silicon nitride film is used, the plasma CVD method may be used, and when the silicon oxide film is used, the sputtering method may be used. At this time, the thickness of the protective film 206 to be formed is appropriately set to the thickness of the silicon substrate 201 used and the thickness required by the etching solution. For example,
Since the etching rate for a potassium hydroxide solution is several Å / min for a silicon nitride film and several tens of Å / min for a silicon oxide film, when using a silicon substrate with a thickness of about 500 μm, the thickness of the protective film should be Respectively,
In the case of a silicon nitride film, the thickness is preferably 0.1 μm to 1.0 μm, and in the case of a silicon oxide film, the thickness is preferably 0.5 μm to 5.0 μm.

Next, as shown in FIG. 2 (f), a protective film 20 is formed.
6 covers the surface of the detection beam portion 208 and the three surfaces of the silicon (111) surface 209 which is a surface adjacent to the surface.
The protection film 206 is patterned. Further, by etching silicon in a potassium hydroxide solution, a mechanical sensor having a detection beam portion 208 as shown in FIG. 2 (h) can be manufactured through the state of FIG. 2 (g). I can. 2C, the etching depth is 0.1 μm to 20 μm, more preferably 0.2 μm.
10 μm. When the etching depth is 0.1 μm or less, the effect of the protective film 206 cannot be sufficiently obtained, and the thickness is 20 μm.
In the above, the unevenness of the silicon substrate is large, and it becomes difficult to uniformly apply the resist during patterning.
Further, as the etching solution, in addition to the potassium hydroxide solution described above, an ethylenediamine pyrocatechol solution,
An anisotropic etching solution such as a tetramethylammonium hydroxide solution and a sodium hydroxide solution may be used. According to the above manufacturing method, since the surface adjacent to the surface of the detection element of the resulting mechanical sensor is sufficiently protected by the protective film, the electrodes and the piezoelectric thin film are not damaged by the etching solution, and Since the side surface of the detection beam portion can be etched into a substantially vertical shape, and the detection element can be formed just outside the detection beam portion, a dynamic sensor with excellent detection sensitivity and strength can be obtained. Become. Further, the mechanical sensor manufactured by the above manufacturing method has less deterioration in the characteristics of the detection element due to moisture in the air and the like, and is excellent in stability.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Example 1 A silicon nitride film having a thickness of 1500 Å was formed on both surfaces of a (100) oriented n-type silicon substrate having a thickness of 525 μm by the LP-CVD method. Next, the silicon nitride film was etched by a plasma method using CF ₄ gas to form an opening for forming a weight portion and a detection beam portion. This board
Etching is performed for 6 seconds in a 15 wt% potassium hydroxide aqueous solution heated to 100 ° C., and the silicon substrate is 0.5 μm.
m etched. Next, a gold thin film having a thickness of 1000 Å was formed by a sputtering method using 50 Å chromium as an undercoat layer and patterned to form a lower electrode. Next, a zinc oxide thin film is formed on the lower electrode by a sputtering method so as to have a thickness of 3000 Å and patterned, and then a gold thin film having a thickness of 1000 Å is further formed on the zinc oxide thin film by a sputtering method. Then, a detection element was formed by forming a pattern of the upper electrode by the lift-off method. Next, on the silicon substrate surface on which the detection element is formed as described above,
As a protective film, a silicon nitride film was formed by heating to 200 ° C. by a plasma CVD method so as to have a thickness of 5000 Å. Next, as shown in FIG. 2F, patterning is performed so that the silicon nitride film, which is a protective film, covers the surface of the detection beam portion and the three surfaces of the silicon (111) surface adjacent to the detection beam portion. And an opening for forming the detection beam. The removal of the silicon nitride film was performed by a plasma method using CF ₄ gas. Further, this substrate was etched in a 15 wt% potassium hydroxide solution heated to 100 ° C. for 90 minutes to form a weight portion and a detection beam portion. In this embodiment, the weight portion has a length of 3 mm and a width of 8 mm, the detection beam portion has a width of 0.05 mm and a length of 2 mm, and the detection element has a width of 0.02 mm. The length was 0.06 mm. In this embodiment, since the surface and the side surface of the detection element are protected by the protective film, the side surface of the detection beam portion is etched into a substantially vertical shape without damaging the electrode and the piezoelectric thin film by the etching solution. I was able to process it.

Example 2 A 1500-Å-thick silicon nitride film was formed by LP-CVD on both surfaces of a (100) -oriented n-type silicon substrate having a thickness of 525 μm. Next, the silicon nitride film was etched by a plasma method using CF ₄ gas to form an opening portion for forming a weight portion and a detection beam portion. This substrate was etched in a 15 wt% potassium hydroxide aqueous solution heated to 100 ° C. for 30 seconds to etch a silicon substrate to a depth of 2.5 μm. Next, after the detection element was formed in the same manner as in Example 1, a silicon oxide film was formed as a protective film on the surface of the silicon substrate on which the detection element was formed by a sputtering method so as to have a thickness of 3.0 μm. did. Next, as shown in FIG. 2F, patterning is performed so that the silicon oxide film covers the three surfaces of the silicon (111) surface which is the surface adjacent to the surface where the detection element of the detection beam portion is formed. An opening for forming the weight portion and the detection beam portion was formed. Incidentally, the removal of the silicon oxide film is performed by C
Reactive ion etching was performed using HF ₃ gas. Further, this substrate was etched in a 15 wt% potassium hydroxide aqueous solution heated to 100 ° C. for 90 minutes to form a weight portion and a detection beam portion.
In this embodiment, the size of the formed weight portion is
The length is 3 mm and the width is 8 mm, and the size of the detection beam is 0.1 width.
mm, length 3 mm, size of detection element is 0.03 m width
m and length 0.08 mm. In this example, since the surface and the side surface of the obtained detection element are protected by the protective film, the side surface of the beam portion for detection is formed in a substantially vertical shape without damaging the electrodes or the piezoelectric thin film by the etching solution. It could be processed by etching.

Embodiment 3 Next, an angular velocity sensor of the present invention will be described. Figure 3
FIG. 4 is a diagram showing an embodiment of an angular velocity sensor of the present invention, in which 301 is a silicon single crystal substrate, 302 is a weight part, and 3 is a weight part.
Reference numeral 03 is a detection beam portion, 304 and 305 are void portions formed as a result of etching removal of a flat substrate, 306 is a detection element, 307 is a driving structure portion, and 308 is a driving structure portion 30.
7, a piezoelectric element for excitation for vibrating 7, an electrode 3
Reference numeral 10 is an electrode lead-out portion, 311 is an angular velocity detection axis, and 312 is a protective film of a characteristic portion of the mechanical sensor of the present invention. In this embodiment, by applying a constant AC voltage to the excitation piezoelectric element 308, the drive structure 307 is vibrated in the direction of arrow X, and the weight 302 and the detection beam 303 are vibrated. When the angular velocity around the detection axis 311 is applied to the vibrating weight portion 302 and the detecting beam portion 303, the weight portion 302 and the detecting beam portion 303 receive the Coriolis force in the direction of arrow F, and the detecting beam portion is detected. 303 is flexurally deformed in the same direction. The amount of this deflection is detected using the detection element 306.

Next, a method of manufacturing the angular velocity sensor of this embodiment will be described with reference to FIG. FIG. 4 is a sectional view taken along a plane parallel to the detection axis 311 shown in FIG. 3, in which 401 is a (100) -oriented single crystal silicon substrate, 402 is a silicon nitride film, and 403 is a lower layer. Electrode, 4
Reference numeral 04 is a piezoelectric thin film, 405 is an upper electrode, 406 is a protective film,
Reference numeral 407 is an opening for forming a weight portion and detection beam portion, 408 is a silicon (111) surface, 409 is an opening for forming a drive structure portion, 410 is a driving piezoelectric body, and 411 is a piezoelectric body. It is an electrode for driving. As shown in FIG. 4A, a (100) orientation n-type silicon substrate 401 having a thickness of 525 μm.
A silicon nitride film 402 having a thickness of 2000 Å was formed on both surfaces of the same by the LP-CVD method. Next, as shown in FIG. 4B, the silicon nitride film 402 is etched by a plasma method using CF ₄ gas to form an opening portion 407 for forming the weight portion 302 and the detection beam portion 303. Formed. This substrate was etched for 12 seconds in a 15 wt% potassium hydroxide aqueous solution heated to 100 ° C. to etch the silicon substrate to a depth of 1.0 μm (FIG. 4).
(C)). Next, as shown in FIG. 4D, a gold thin film having a thickness of 1000 Å is formed by sputtering as a subbing layer of chromium having a thickness of 50 Å and patterned to form a lower electrode 403.
Was formed. A PZT thin film was formed on the lower electrode 403 by a sputtering method so as to have a thickness of 4000 Å and patterned to form a piezoelectric thin film 404. Next, a metal film having a thickness of 1000Å is formed on the piezoelectric thin film 404 by a sputtering method, an upper electrode 405 is formed by a lift-off method, and the PZT thin film is polarized.
The detection element 306 shown in FIG.

Next, as shown in FIG. 4 (e), a silicon nitride film was heated to 200 ° C. by a plasma CVD method to form a protective film 406 with a thickness of 6000 Å. Next, the protective film 406 is patterned so as to cover the surface of the detection beam portion 303 on which the detection element is formed and the silicon (111) surface (not shown) that is a surface adjacent thereto, and the weight portion 302 is formed. And an opening for forming the detection beam portion 303 was formed (FIG. 4F). The removal of the silicon nitride film 402, which is a protective film, was performed by a plasma method using CF ₄ gas. Next, this substrate was etched for 30 minutes in a 15 wt% potassium hydroxide aqueous solution heated to 100 ° C. (FIG. 4).
(G)), as shown in FIG. 4 (h), a silicon nitride film 40
2 was removed by etching to form an opening 407 for forming the drive structure 307. Then, this substrate
9% in 15% by weight potassium hydroxide aqueous solution heated to ℃
Etching was performed for 0 minutes to obtain the structure shown in FIG. Next, as shown in FIG. 4J, an aluminum thin film to be the driving electrodes 411 was formed on both surfaces. Further, a piezoelectric body 410 made of lead zirconate titanate (PZT) having a thickness of 300 μm was adhered using an epoxy adhesive to manufacture the angular velocity sensor of the present invention. In the present embodiment, the size of the formed weight portion is 3 mm in length,
6 mm in width, 6 mm in length, 6 mm in width, 0.3 mm in thickness, the size of the beam portion for detection is 0.05 mm in width, 2 mm in length, and the size of the detection element is width. The length was 0.02 mm and the length was 0.07 mm. When the angular velocity sensor of this example manufactured as described above was driven at the resonance frequency to detect the output potential difference between the two detection elements, the detection shaft 31 shown in FIG.
It was possible to satisfactorily detect the angular velocity of one turn. Further, there was little variation in detection characteristics and deterioration with time, and the stability was excellent.

Embodiment 4 Next, an acceleration sensor of the present invention will be described. Figure 5
FIG. 3 is a diagram showing an embodiment of an acceleration sensor of the present invention. In the acceleration sensor of this embodiment, two sensors, sensor a and sensor b, are formed on the same plane, and biaxial detection in the arrow A direction and the arrow B direction is possible. In the figure, 501 is a silicon single crystal substrate, 502a and 502b are weight parts,
Reference numerals 503a and 503b denote detection beam portions, and 504 and 505.
Is a void formed by etching removal, 506a and 506b are detection elements, 507a and 507b are electrodes,
Reference numerals 08a and 508b denote electrode lead portions, and 509 denotes a protective film which is a characteristic portion of the mechanical sensor of the present invention. The acceleration sensor of this embodiment can be manufactured according to the manufacturing method of the angular velocity sensor of the third embodiment. In this embodiment, the outer dimensions of the sensor a and the sensor b are 4 mm in length and 10 mm in width,
The thickness of the detection beam portion 503a of the sensor a is 0.02 mm,
The width of the detection beam portion 503b of the sensor b was 0.05 mm. When the acceleration sensor of this embodiment as described above was used for detection, the acceleration in the biaxial directions could be satisfactorily detected. Also, there are few variations in detection characteristics and deterioration over time,
It was excellent in stability. Further, by forming a sensor portion having the same shape as the sensor b in a direction orthogonal to the sensor b by 90 °, three-axis detection becomes possible. As described above, according to the present invention, it is possible to provide a thin sensor capable of multi-axis detection.

[0020]

As described above, in the dynamic sensor of the present invention, since the three surfaces of the detection beam portion on which the detection element is formed and the surface adjacent thereto are sufficiently protected by the protective film, Since the side surface of the detection beam portion can be etched into a vertical shape without damaging the detection element by the etching solution, and the detection element can be formed just outside the detection beam portion. , With excellent detection sensitivity and strength. In addition, the mechanical sensor of the present invention is excellent in stability with little deterioration of the characteristics of the detection element due to moisture in the air.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a detection beam portion of a dynamic sensor of the present invention.

FIG. 2 is a diagram showing a method of manufacturing the mechanical sensor of the present invention.

FIG. 3 is a diagram showing an embodiment of an angular velocity sensor of the present invention.

FIG. 4 is a diagram showing a method of manufacturing the angular velocity sensor of the present invention.

FIG. 5 is a diagram showing an embodiment of an acceleration sensor of the present invention.

6A and 6B are diagrams showing a conventional semiconductor angular velocity sensor and a detection unit of an acceleration sensor, FIG. 6A is a top view, and FIG. 6B is a cross-sectional view taken along the line AA ′ of FIG.

FIG. 7 is a diagram showing a progress state of etching silicon.

[Explanation of symbols]

101, 201, 301, 401, 501, 601, 7
01: Silicon substrate 102, 202, 402, 702: Silicon nitride film 103, 203, 403, 606: Lower electrode 104, 204, 404, 607: Piezoelectric thin film 105, 205, 405, 608: Upper electrode 106, 206, 312, 406, 509: Protective film 207, 407, 409: Opening part for etching 302, 502a, 502b, 602: Weight part 208, 303, 503a, 503b, 603: Beam part for detection 209, 408, 703: Silicon (111) surface 304, 305, 504, 505: Void portion 306, 506a, 506b, 604: Detection element 307: Driving structure portion 308, 410: Driving piezoelectric element 309, 507a, 507b: Electrode 310, 508a, 508b : Electrode extraction part 311, 609: Each speed detection shaft 411: Insulation

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihisa Sano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. A flat substrate is etched to integrally form a detection beam portion and a weight portion, and the deformation amount of the weight portion that causes the detection beam portion to be deformed by an external force is detected. In a dynamic sensor provided with a detection element, a substrate portion of the detection beam portion has a substantially octagonal cross-sectional shape, and a surface of the detection beam portion on which the detection element is formed and two surfaces adjacent to the surface. A dynamic sensor having three surfaces covered with a protective film. 2. The side surface of the detection beam portion formed by etching a flat plate-shaped substrate is substantially vertical to the surface of the detection beam portion on which the detection element is provided. The described mechanical sensor. 3. The dynamic sensor according to claim 1, wherein a height of the beam of the detection beam portion is larger than a width of the beam. 4. The flat substrate is a silicon single crystal,
The dynamic sensor according to claim 1, wherein the protective film is a silicon nitride film or a silicon oxide film. 5. The detection element is made of a piezoelectric material.
The dynamic sensor according to. 6. A step of patterning a mask material on both sides of a flat substrate, a step of etching a part of the flat substrate to a slight depth from both sides, and a step of forming a detection element on the flat substrate. A step of forming a protective film on the detecting element, and protecting the protective film so as to cover the surface on which the detecting element is formed and the two surfaces adjacent to the surface formed by etching. And a step of completely removing the flat substrate from both sides after etching away a part of the film. 7. The dynamic sensor according to claim 1, wherein the angular velocity is detected by the amount of deformation of the weight portion that is deformed by an external force. 8. The dynamic sensor according to claim 1, wherein the acceleration is detected by the amount of deformation of the weight portion that is deformed by an external force.