JPH0618552A - Semiconductor acceleration sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] A single semiconductor acceleration sensor having a simple structure can detect accelerations received from a plurality of directions. [Structure] An acceleration sensor is composed of a lower semiconductor portion 10 and an upper semiconductor portion 20 which are insulated from each other by an insulating film 30, and a support portion 25 fixed to the lower semiconductor portion 20 on the upper semiconductor portion 20 and a diaphragm portion 26 and A mass portion 21 suspended elastically in a pendulum shape via a rod-shaped suspension portion 27 is provided, and a plurality of electrode films 14 facing the mass portion 21 with a narrow gap on the upper surface of the lower semiconductor portion 10. 15a, 15b, 16a, 16b are created by impurity diffusion, and when the acceleration is received from the z direction, the x direction, or the y direction perpendicular to the paper surface, the mass part 21 is displaced and the capacitance between each of them and each electrode film. It is possible to detect acceleration in two or three directions from the change of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called capacitance type acceleration sensor composed of a pair of semiconductor parts,
The present invention relates to a semiconductor acceleration sensor suitable for detecting acceleration composed of components in at least two directions perpendicular to each other.

[0002]

2. Description of the Related Art A sensor using a semiconductor device has an advantage that it can be formed in a very small size of several mm square or less and can be built in a common semiconductor chip together with related circuits, and is suitable as a mass production sensor for detecting pressure and acceleration. . By the way, in order to detect such a physical quantity, it is necessary to build a movable part in the sensor.Therefore, diaphragm type and cantilever type structures have been mainly adopted from the past, but here, in order to increase the acceleration detection sensitivity, A representative example of a cantilever type semiconductor sensor which is advantageous in increasing the displacement of the movable part will be briefly described with reference to FIG.

A semiconductor plate 51 shown in FIG. 5 is a movable portion side, and a flexible cantilever portion is formed by cutting a groove 51a by photoetching a substrate made of thin single crystal silicon or the like.
52 and the mass 53 supported thereby are formed. The other semiconductor plate 54 is also photo-etched to
A recess 54a is formed at a location corresponding to 53. In the illustrated example, the electrode films 55 are formed on the lower surface of the semiconductor plate 51 and the upper surface of the semiconductor plate 54, respectively.
And 56 are attached to both plates 51 and 52 to each other through them, and the terminals for the sensor are led out from the electrode films 55 and 56, respectively. A capacitance having a narrow gap G is formed between the electrode film 55 on the lower surface of the mass portion 53 and the electrode film 56 on the bottom surface of the recess 54a. In the semiconductor acceleration sensor 50 having such a structure, when the acceleration is applied to the mass portion 53 in the direction indicated by z, the cantilever portion 52 is bent and the gap G is changed. Can be detected.

[0004]

The above-mentioned semiconductor acceleration sensor 50 can be constructed in a very small size and can be incorporated in an integrated circuit chip together with related circuits, but the acceleration is oblique compared to when acceleration is applied from the z direction in FIG. Since the detection sensitivity when it is applied from the direction decreases considerably, for example, when incorporating it into an automobile to detect a collision, even if the sensitivity to a frontal collision is high, it can detect a diagonal or lateral collision. There is a problem that the sensitivity is insufficient and personal protection cannot be adequately achieved.

To solve this problem, it is sufficient to combine two or three acceleration sensors whose sensitive directions are orthogonal to each other and electrically combine their detection signals. With the structure shown in FIG. Since it is very difficult to incorporate multiple acceleration sensors in the same chip with different sensitivity directions, the number of chips or sensors will increase, which makes mounting and wiring between them much easier, and makes it easier to pick up noise. Therefore, the risk of erroneous detection is increased and the reliability is significantly reduced. Under such circumstances, it is an object of the present invention to be able to detect acceleration applied from two or three directions with a single acceleration sensor having a simple structure.

[0006]

According to the present invention, an acceleration sensor is composed of a pair of upper and lower semiconductor parts which are insulated from each other, and a support part fixed to the lower semiconductor part is provided in the upper semiconductor part and a pendulum-like and elastic part. And a plurality of electrode layers facing each other with a gap between them are formed on the surface of the lower semiconductor part by impurity diffusion, and the mass part is subjected to acceleration when subjected to acceleration. The above object is achieved by displacing and detecting the acceleration in the suspending direction and the direction perpendicular thereto from the change in capacitance between each electrode layer.

The lower semiconductor portion is provided with an electrode layer disposed in the center of the lower side of the mass portion and an electrode layer disposed so as to make a pair at the opposite positions around the mass portion, and the mass portion and the central electrode are provided. The acceleration applied to the mass part from the suspension direction is detected from the change in the capacitance between the layers, and from the differential change in the capacitance between the mass part and the surrounding electrode layer pairs, the direction perpendicular to the suspension is detected. It is advantageous to detect the applied acceleration in order to separate and detect the acceleration received by the sensor into a plurality of components in mutually independent directions. Further, in this embodiment, a recess is provided in the surface portion of the lower semiconductor portion, and the mass portion of the upper semiconductor portion is formed in a shape that faces the surface of the recess portion and is opposed to the recess portion with a narrow gap. It is particularly desirable to dispose the central electrode layer on the bottom surface of the and the peripheral electrode layer pair on the side surface of the recess in order to enhance the detection sensitivity. In addition,
The vertical cross-sectional shape of the recess on the upper semiconductor portion side may be formed in a deep dish shape or a rectangular shape, for example.

When the central electrode layer and the peripheral electrode layer pair are provided in this way, the former terminal may be provided on the back surface side of the lower semiconductor portion, but the terminal is required to incorporate the acceleration sensor into the integrated circuit. It is advantageous to provide it on the front side. To this end, the lower semiconductor portion is configured such that an epitaxial layer of the other conductivity type is grown on a substrate of one conductivity type and a buried layer of the other conductivity type is provided between the two, and the surface of the epitaxial layer is formed. It is preferable that the central electrode layer and the terminal connection layer are diffused with the other conductivity type so as to reach the buried layer, and the terminal for the central electrode layer is provided on the surface of the latter connection layer.

In order to make the displacement of the mass part of the upper semiconductor part large and smooth when acceleration is applied to the sensor of the present invention, the support part is formed in a cylindrical shape, and the periphery is fixed to this support part. It is advantageous to adopt a structure in which the mass portion is suspended on the support portion via the diaphragm portion and the rod-shaped suspension portion fixed to the center thereof. In this mode, in order to increase the displacement of the mass part as much as possible in order to increase the detection sensitivity, it is preferable to form the suspension part to be thin, but there are some problems in strength, so the diaphragm part should be formed to be thin. It is advantageous to provide the window with it to increase its flexibility.

In terms of manufacturing the semiconductor acceleration sensor of the present invention, it is advantageous that the lower semiconductor portion is made of a single crystal semiconductor and the upper semiconductor portion is made of a polycrystalline semiconductor grown on the insulating semiconductor film via an insulating film. is there. The manufacturing method in this case is to cover the upper surface of the lower semiconductor part with a thin oxide film and to attach an insulating film for insulation with the upper semiconductor part where necessary, and to deposit a polycrystal film on the thin oxide film. A step of arranging a mass part of the semiconductor, a step of depositing a thick oxide film on the entire surface and cutting a groove for a supporting part and a suspension part, and a polycrystalline semiconductor so as to fill the groove and cover the thick oxide film. And a step of opening an etching window on the upper side of the thick oxide film of the polycrystalline semiconductor and removing the thick oxide film and the thin oxide film by chemical etching through this window. Is advantageous. When the oxide film is silicon oxide, the etching in the final step can be easily performed using hydrofluoric acid, and it is preferable to use silicon nitride or the like which is not etched by the insulating film between the two semiconductor portions.

[0011]

According to the present invention, the sensor receives the acceleration by suspending the mass portion of the upper semiconductor portion from the support portion fixed to the lower semiconductor portion in a pendulum-like manner and elastically as described in the construction of the preceding paragraph. At this time, the mass part can be displaced both in the suspension direction and in the direction perpendicular thereto, and correspondingly, the lower semiconductor part is provided with a plurality of electrode layers facing the mass part with a narrow gap. Therefore, no matter which direction the acceleration is applied, the components in the three directions or at least two directions of the acceleration can be detected by a single semiconductor acceleration sensor based on the change in the capacitance between the mass part and each electrode layer based on the applied displacement. It was done like this.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a semiconductor acceleration sensor according to the present invention and its operation in a sectional view and a top view, FIG. 2 shows an example of its manufacturing method in a sectional view, and FIG. 3 shows a different embodiment in a sectional view. FIG. 4 is a sectional view showing an example of the manufacturing method. In the embodiments described below, one electrode layer and a pair of electrode layers are provided in the center of the lower semiconductor portion, a single crystal semiconductor is used for the lower semiconductor portion, and a polycrystalline semiconductor is used for the upper semiconductor portion. Although configured, the present invention is not limited to such a structure and can be implemented in various forms.

Lower semiconductor portion shown in cross section in FIG. 1 (a)
Reference numeral 10 is made of single crystal silicon. In this example, a strong p-type buried layer 12 is diffused on the surface of a p-type semiconductor substrate 11 in a predetermined pattern, and then an n-type epitaxial layer 13 is grown. At the central portion of the upper surface of the lower semiconductor portion 10, the electrode layer 14 is diffused deeply so as to reach the buried layer 12 with a strong p-type, and the electrode layer 15a is formed at a position facing the periphery thereof as shown in FIG. 1 (b). , 15b and the pair 16 of electrode layers 16a, 16b are shallowly diffused with a strong p-type. The pattern of the buried layer 12 is composed of a central portion and an extending portion to the lower right of the figure, and the p-type connecting layer 12a is deep from the surface of the lower semiconductor portion 10 so as to reach the end portion of the extending portion. Diffused. The patterns of the electrode layers 15a, 15b and 16a, 16b also include fan-shaped portions and outwardly extending portions for terminals.

The upper semiconductor portion 20 of FIG. 1A is made of polycrystalline silicon and is fixed or mounted on the upper surface of the upper semiconductor portion 10 with an insulating film 30 interposed therebetween. Upper semiconductor part of the example shown
20 has a structure in which a disc-shaped mass portion 21 is suspended from the upper end of a cylindrical support portion 25 via a thin diaphragm portion 26 and a thin rod-shaped suspension portion 27, and the diaphragm 26 has a plurality of windows.
To increase its flexibility, 24 are laid out radially, for example in a slit-like pattern. In FIG. 1 (b), the mass portion 21 and the support portion 25 of the upper semiconductor portion 20 are shown by broken lines for convenience of illustration. As shown in the figure, a terminal overhanging portion 28 is provided on the insulating film 30 from a part of the outer periphery of the supporting portion 25.

As shown in FIG. 1B, a single terminal 40 is provided for the upper semiconductor portion 20 by a metal film such as aluminum connected to the projecting portion 28. A terminal is led out to the lower semiconductor portion 10 by a metal film provided at a portion of the window 31 of the insulating film 30 shown in FIG. As shown in FIG. 1 (b), a terminal 41 is provided on the connection layer 12a connected to the above-mentioned buried layer 12 for the central electrode film 14, and for the electrode layers 15a and 15b of the pair 15, those terminals are provided. Terminals 42a and 42b are provided on the extending portions, respectively, and similarly terminals 43a and 43b are provided for the electrode layers 16a and 16b of the pair 16, respectively. The acceleration sensor constructed as shown in FIGS. 1 (a) and 1 (b) can be manufactured by forming the upper semiconductor portion 20 on the lower semiconductor portion 10 using the semiconductor manufacturing process technology as described later. It can be miniaturized to about 3 mm square or incorporated into a chip of an integrated circuit device together with related circuits.

FIGS. 1 (c) and 1 (d) are cross-sectional views showing the state when the acceleration is applied. As shown in FIG. 1 (c), when the acceleration in the z direction is applied to the mass part 21, the diaphragm part is bent or suspended.
Due to the expansion and contraction of 27, the gap between the mass portion 21 and the central electrode layer 14 changes by δ in the figure, and the acceleration is detected from the change in the capacitance between them. As shown in FIG. 1 (d), when the acceleration in the x direction is applied, the mass part 21 is inclined by θ in the figure due to the deflection of the diaphragm part 26 and the suspension part 27, and the two parts between the mass part 21 and the electrode layers 15a, 15b are provided. Acceleration is detected from the differential change in the capacitance of the. Similarly, when an acceleration in the y direction perpendicular to the paper surface is received, the acceleration is detected from the differential change in the capacitance between the mass portion 21 and the electrode layers 16a and 16b.

Next, an example of a method of manufacturing the acceleration sensor of the embodiment shown in FIG. 1 will be described with reference to FIG. In the state of FIG. 2A, the lower semiconductor portion 10 has a strong p-type substrate 11 as described above.
The n-type epitaxial layer 13 after diffusing the n-type buried layer 12
From the surface of the p-type central electrode film 14
So as to reach the buried layer 12, the surrounding electrode films 15a, 15b, etc. are diffused at a high impurity concentration of 10 ¹⁸ atoms / cm ³ or more, for example, to a depth of 2 μm. Further, in this step, the oxide film 17 is deposited on the surface of the lower semiconductor portion 10 to a thickness of 0.5 to 1 μm. The thickness of the oxide film 17 sets the gap length between the electrodes of the capacitance for acceleration detection.

In the step of FIG. 2B, an insulating film 30 of silicon nitride or the like is formed on the surface of the lower semiconductor portion 10 by the CVD method to a film thickness of, for example, about 2 μm, and photoetching is performed. As described above, the pattern is formed so as to cover almost the entire surface except the central portion and to have a window 31 for a terminal at a key portion. The step of forming the insulating film 30 in FIG. 2B and the step of depositing the oxide film 17 in FIG. 2A may be interchanged. In the next step of FIG. 2 (c), polycrystalline silicon is CVD
The mass portion 21 is arranged in a disc-shaped pattern on the oxide film 17 by growing the film to a film thickness of 10 to 50 μm by a method and performing photoetching. It is preferable that the polycrystalline silicon for the mass part 21 has high conductivity by CVD growth in an atmosphere containing impurities for doping, for example.

In the step shown in FIG. 2D, the oxide film 22 is formed, for example, by a thermal CVD method in an atmosphere gas containing silane and oxygen.
Insulate the thin circular groove 22a that exposes the center of the mass 21 as shown in the figure by performing reactive ion etching using a fluorine-based gas after growing the entire surface to a thickness of 00 to several hundreds of μm. An annular groove that exposes a portion of the membrane 30
22b is dug deep under anisotropic etching conditions. Further, in the step of FIG. 2 (e), the polycrystalline silicon 23 is grooved as shown in the figure.
After growing thickly in the same manner as for the mass part 21 so as to fill 22a and 22b and cover the upper surface of the oxide film 22, so-called etch back is performed to flatten the upper surface as shown in the figure. The film thickness of the upper portion of the oxide film 22 of the polycrystalline silicon 23 is preferably several to 30 μm, for example.

In the step of FIG. 2F, the upper semiconductor portion 20 is formed by chemical etching. First of all, the oxide film 22 in FIG.
After opening the window 24 in the upper polycrystalline silicon 23, the oxide film 22 and the oxide film 17 therebelow are removed by etching through the window 24 by means such as spraying a hydrofluoric acid solution. ) State. At this time, since the insulating film 30 of silicon nitride is not etched by the hydrofluoric acid solution, only the polycrystalline silicon remains on the upper side of the lower semiconductor portion 10 except for the insulating film 30, and the cylindrical support portion 25 described above is used. The upper semiconductor portion 20 is formed of the disk-shaped diaphragm portion 26, the suspension portion 27, and the mass portion 21 suspended from the suspension portion 27. Note that the above windows
When opening 24, an opening is also provided in the polycrystalline silicon 23 of FIG. 2 (e) corresponding to the outside of the support portion 25, and the oxide films 30 and 17 thereunder are removed by etching. After the step of FIG. 2 (f), a metal film for a terminal is provided in the window 31 of the insulating film 30 to complete the state of FIG. 1 (a).

FIG. 3 shows a different embodiment of the present invention in a sectional view corresponding to FIG. 1 (a). Parts corresponding to those in FIG. 1 are designated by the same reference numerals. In this example, the lower semiconductor portion
A recess 19 is dug in the central portion of the upper surface of the upper portion 10, and accordingly, a mass portion 21 of the upper semiconductor portion 20 is formed along the surface of the recess 19 so as to face it with a narrow gap. In the illustrated example, the recess 19 is dug into a deep dish, and the central electrode layer 14 is provided on the bottom surface thereof, and the peripheral electrode layers 15a, 15b, etc. are provided on the oblique side surfaces thereof. Therefore, the electrode layers 15a, 15b, etc. are diffused deeper than in the case of the embodiment of FIG. The structure other than these points is the same as that of the previous embodiment.

In the embodiment of FIG. 3, the change in the electrostatic capacitance between the mass portion 21 and the central electrode layer 14 when the mass portion 21 receives acceleration in the z direction is the same as that of the embodiment of FIG. Acceleration is x
Mass part 21 when hung in the direction y or the direction perpendicular to the paper surface
Since the differential change in the electrostatic capacitance between the electrode layers 15a, 15b, etc., and the surrounding electrode layers is larger than that in the case of FIG. 1, there is an advantage that the detection sensitivity to the lateral acceleration is high. As can be easily seen, this detection sensitivity becomes higher as the side surface of the recess 19 becomes steeper, and it is advantageous to improve the sensitivity to form the recess 19 in a rectangular vertical sectional shape.

The essential points of the manufacturing method suitable for the acceleration sensor having the structure of FIG. 3 will be described with reference to FIG. Figure 4 (a)
Shows the state corresponding to the previous Figure 2 (a), the lower semiconductor part
Although the upper surface of 10 is covered with a thin oxide film 17, as described above, the surrounding electrode layers 15a, 15b, etc. are diffused deeper than in the case of FIG. 2 (a), for example, to a depth of several to 10 μm. Is different. In the next FIG. 4 (b), in order to dig a recess 19, a thick oxide film 18 is grown by the so-called L0COS method in this embodiment. Therefore, a thick oxide film 18 is formed on the lower semiconductor portion 10 by performing a thermal oxidation process at a high temperature on the oxide film 17 outside the range where the oxide film 18 should be grown while being covered with the silicon nitride film 18a. As shown in the figure, the surface is made to dig into a dish shape for 5 μm or more to grow. After this, the lower semiconductor part 10
Of the silicon nitride film 18a and the oxide films 17 and 18 from the surface of the
Remove all.

In FIG. 4 (c), the oxide film 17a is reattached on the surface of the lower semiconductor portion 10 to a thickness of 0.5 to 1 .mu.m, for example, and the insulating film 30 of silicon nitride is provided as shown in FIG. 2 (b). Then, as shown in FIG. 2 (c), the polycrystal silicon mass part 21 is recessed.
It is provided above the oxide film 17a that covers 19. As a result, the mass portion 21 is formed in a shape along the dish-shaped surface of the recess 19. After that, the steps of FIGS. 2D to 2F may be performed, and then the terminals of the metal film may be arranged to complete the state of FIG. In the example of the manufacturing method shown in FIG. 4, the thick oxide film 18 formed by the L0COS method was used to form the recess 19 in the shape of a dish. In the step (b), this may be dug by photoetching.

In the semiconductor acceleration sensor of the embodiment shown in FIGS. 1 and 3 described above, a single sensor can detect acceleration applied to the mass portion in two directions of z and x or in three directions including the y direction. In addition, the acceleration components in these directions can be electrically separated from each other and detected. Also, by appropriately synthesizing the electric signal obtained from the capacitance between the mass part and each electrode film, for example, the impact force from the front as well as the lateral direction is added so that it is most suitable for personal protection in the event of an automobile collision. The acceleration detection value having the desired angular sensitivity characteristic can be created.

[0026]

As described above, according to the present invention, the acceleration sensor is composed of a pair of upper and lower semiconductor parts which are insulated from each other, and the upper semiconductor part is fixed to the lower semiconductor part, and the supporting part and the pendulum shape. In addition, a mass part that is elastically suspended is provided, and a plurality of electrode layers facing the mass part through a gap are formed in the surface part of the lower semiconductor part by impurity diffusion, and the mass part is formed when an acceleration is applied. The following effects can be obtained by displacing and detecting the acceleration in the suspending direction and the direction perpendicular to it from the change in capacitance between each electrode layer.

(A) Pendantly and elastically suspending the mass part from the support part to displace the mass part both in the suspending direction and in a direction perpendicular to it when an acceleration is applied, and the resulting capacitance The acceleration applied from two or three directions due to the change can be detected by a single acceleration sensor, and the detection sensitivity can be increased by appropriately selecting the elastic value of suspension with respect to the mass portion.

(B) Since a plurality of electrode layers are provided and an electrostatic capacitance is formed between each of them and the mass part, each directional component of acceleration is independently detected from the change in each electrostatic capacitance when receiving acceleration. Further, by appropriately combining or combining the detection signals due to the change in the electrostatic capacity, it is possible to detect the acceleration with the sensitivity direction characteristic most suitable for the intended use or purpose.

In addition to these effects, the acceleration sensor of the present invention can be formed into a miniature size of 2 to 3 mm square by utilizing semiconductor process technology, can be easily incorporated into an integrated circuit chip together with related circuits, and can be provided at low cost. The present invention has the advantage that it can be applied to the detection of a collision of an automobile and the like, and can exert an effect of detecting acceleration with a desired directional sensitivity characteristic.

[Brief description of drawings]

FIG. 1 shows an embodiment of a semiconductor acceleration sensor according to the present invention, where FIG. 1 (a) is a longitudinal sectional view thereof, FIG. 1 (b) is a top view of a lower semiconductor portion, and FIGS. [Fig. 3] is a cross-sectional view of essential parts showing states when acceleration is applied from the z direction and the x direction, respectively.

2 shows an example of a method of manufacturing a semiconductor acceleration sensor corresponding to the embodiment of FIG. 1, where FIG. 2 (a) is an oxide film deposition step, FIG.
(b) is the step of forming the insulating film, (c) is the step of arranging the mass parts of polycrystalline silicon, (d) is the step of growing the oxide film,
(e) is a cross-sectional view of a lower semiconductor portion and an upper semiconductor portion, showing a state in a polycrystalline silicon growth step and a state in an etching step, respectively.

FIG. 3 is a vertical sectional view showing another embodiment of the semiconductor acceleration sensor according to the present invention.

4A and 4B show the main points of a method of manufacturing a semiconductor acceleration sensor corresponding to the embodiment of FIG. 3, where FIG. 4A is an oxide film deposition step, and FIG. 4A is a thick digging for a recess. FIG. 3C is a cross-sectional view of the lower semiconductor portion showing the states of the oxide film growing step, the insulating film forming step, and the polycrystalline silicon mass part arranging step.

FIG. 5 is a perspective view showing an outline of the structure of a conventional semiconductor acceleration sensor for a cantilever sensor.

[Explanation of symbols]

 10 Lower semiconductor part 14 Central electrode layer 15a Peripheral paired electrode layer 15b Peripheral paired electrode layer 16a Peripheral paired electrode layer 16b Peripheral paired electrode layer 19 Recess 20 Upper semiconductor part 21 Mass part 24 Window of diaphragm part 25 Bearing part 26 Diaphragm part 27 Suspension part 30 Insulation film x Direction of acceleration z Direction of acceleration

Claims (4)

[Claims] 1. A sensor for detecting acceleration from a change in capacitance formed between a pair of upper and lower semiconductor parts insulated from each other, wherein an upper semiconductor part is fixed to a lower semiconductor part. A support part and a mass part that is pendulum-like and elastically suspended from the support part, and a plurality of electrode layers facing the mass part through a gap are diffused into the surface part of the lower semiconductor part, and the mass is applied when an acceleration is applied. A semiconductor acceleration sensor, wherein the acceleration of the mass part in the suspension direction and the direction perpendicular to the mass part can be detected from the change of the capacitance between the mass part and the electrode layer. 2. The electrode according to claim 1, wherein the lower semiconductor portion is arranged so as to make a pair at a position facing the electrode layer arranged at the center of the lower side of the mass portion and its periphery. Layer, the acceleration applied in the suspension direction of the mass part due to the capacitance change between the mass part and the central electrode layer, in the direction perpendicular to the suspension due to the capacitance change between the mass part and the surrounding electrode layer pair. A semiconductor acceleration sensor characterized in that the applied acceleration is detected respectively. 3. The sensor according to claim 2, wherein a recess is provided in a surface portion of the lower semiconductor portion, and a mass portion of the upper semiconductor portion is formed in a shape facing the surface of the recess with a gap. The semiconductor acceleration sensor is characterized in that the central electrode layer is disposed on the bottom surface of the recess and the peripheral electrode layer pair is disposed on the side surface of the recess. 4. The sensor according to claim 1, wherein the lower semiconductor portion is composed of a single crystal semiconductor, and the upper semiconductor portion is composed of a polycrystalline semiconductor grown on the insulating semiconductor film. Characteristic semiconductor acceleration sensor.