JPH07254716A - Semiconductor capacity type acceleration sensor and its production - Google Patents

Abstract

PURPOSE:To provide a semiconductor capacity type acceleration sensor and its production method in which larger differential output can be obtained and higher detection sensitivity be also realized by narrowing an interval between electrodes to the maximum. CONSTITUTION:A mass part 22 constituting a movable electrode 21 which is supported by a beam is placed in a floating state, in a groove 16 prepared on the surface of a semiconductor, and the change of electrostatic capacity between the side face of the groove 16 and the electrode 21 is detected through its difference. The narrow interval between the side face of the groove 16 prepared on the surface of the semiconductor and the electrode 21 is made narrower to the maximum by using a sacrifice layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor capacitive acceleration sensor utilizing electrostatic capacitance change and a method of manufacturing the same.

[0002]

2. Description of the Related Art A semiconductor type acceleration sensor is used, for example, for detecting the acceleration of a vehicle and adjusting the spring constant of a suspension mechanism at the time of starting or decelerating to keep the vehicle running stable. As an example of a sensor, a sensor that utilizes a change in electrostatic capacitance is known.

FIG. 9 is a sectional view of a detecting portion of a semiconductor capacitive acceleration sensor disclosed in Japanese Patent Laid-Open No. 3-94168.

A quadrilateral movable electrode portion 2 which is a mass body is provided in the central portion of a silicon substrate 1 having a side length of 5 mm, and four windmill-shaped portions elastically supporting the central portion in the thickness direction of the movable electrode portion 2 are provided. Beams 3 are formed. The length of the beam 3 is at least 50% or more of the length of one side of the movable electrode portion 1. Glass substrates 4 and 5 are provided on the upper surface and the lower surface of the silicon substrate 1 having this structure, respectively, and fixed electrodes 6 and 7 are formed on the facing surface of the movable electrode portion 2. The distance L between the movable electrode portion 2 and the fixed electrodes 6 and 7 is several μm, and capacitors C1 and C2 are formed by a pair of electrodes facing each other. In this semiconductor capacitive acceleration sensor, since the center of gravity of the movable electrode portion 2 is located on the central axis of the beam 3, Z
The movable electrode portion 2 is largely displaced with respect to the acceleration component in the direction, and is substantially equal to zero with respect to the acceleration in the X and Y directions.

When the movable electrode portion 2 is displaced in the Z direction according to the acceleration, the distance L between the movable electrode portion 2 and the fixed electrodes 6 and 7 changes, and the electrostatic capacitance of the capacitors C1 and C2 changes. The semiconductor capacitance type acceleration sensor takes out this electrostatic capacitance change as a differential output.

Next, an outline of a method of manufacturing this semiconductor capacitive acceleration sensor will be described. The movable electrode portion 2 and the beam 3 in the central portion of the silicon substrate 1 are formed by anisotropic etching. Next, fixed electrodes 6 and 7 are formed on the surfaces of the glass substrates 4 and 5 facing the movable electrode portion 1. After that, the silicon substrate 1 and the glass substrates 4 and 5 are integrally formed by anodic bonding.

FIG. 10 is a sectional view of the detecting portion of the semiconductor capacitive acceleration sensor disclosed in Japanese Patent Laid-Open No. 2-309259.

A cantilever beam 9 is formed at an appropriate depth position from the surface of the silicon substrate 8 in a direction perpendicular to the surface. At the tip of the cantilever 9, a mass portion 10 to which a detected acceleration is applied is formed symmetrically with respect to the cantilever 9. Further, side wall portions 11 serving as stoppers are provided at predetermined intervals on both sides of the mass portion 10. The stopper is for preventing the cantilever beam 9 from being largely displaced and broken when an excessive acceleration is applied to the mass portion 10. Electrodes 12 are respectively deposited on the insulating layers (not shown) on the opposing surfaces of the mass portion 10 and the side wall portion 11 to form capacitors C3 and C4. Similar to the semiconductor capacitance type speed sensor shown in FIG. 9, when acceleration is applied, the mass portion 10 is displaced and the electrostatic capacitances of the capacitors C3 and C4 are changed, and a differential output corresponding to the acceleration is taken out.

Next, an outline of a method of manufacturing this semiconductor capacitive acceleration sensor will be described. The surface of the silicon substrate 8 forming the mass portion 10 is masked, and RIE (Reactive) is performed.
The trench 13 is formed perpendicular to the surface of the silicon substrate 8 by an anisotropic etching method such as Ion Etching). After forming an insulating layer on the entire surface of the silicon substrate 8 by a method such as thermal oxidation, CVD (Chemical V
A metal film to be the electrode 12 is formed on the side wall of the trench 13 by a method such as apour deposition). After that, anisotropic etching is performed again to dig down the trench 13, and only the lower portion of the trench 13 is anisotropically etched using an alkaline aqueous solution such as potassium hydroxide or hydrazine to form the cantilever 9 and the mass portion 10. To do.

[0010]

First, the semiconductor capacitive acceleration sensor shown in FIG. 9 has the following problems.

When the electrode area of the capacitors C1 and C2 is S, the electrode interval is L, and the displacement of the movable electrode portion 2 is δ, the electrostatic capacitances of the capacitors C1 and C2 when acceleration is applied are ε.S ./ ( L-δ), ε · S · / (L + δ), and when this is taken out as a differential output, the difference is 2ε · S.
・ Because it is approximated by δ / L ・ L, the electrode area S is wide,
The smaller the electrode interval L, the larger the output. However, in the semiconductor capacitive acceleration sensor, it is difficult to uniformly and accurately make a narrow gap L of several μm or less by etching, so that the characteristics of each sensor vary.
Adjustment was required for each sensor. Therefore, in the sensor of FIG. 9, a large output is obtained by increasing the electrode area S, but as a result, the shape of the semiconductor capacitive acceleration sensor is large.

At the time of manufacturing, since the movable electrode portion 2 and the beam 3 are formed by wet etching, it is difficult to accurately determine the dimension of the beam 3. For this reason, the displacement movement of the movable electrode portion 2 differs for each element, which causes a variation in output according to a change in acceleration. Also, the electrode spacing L
Is difficult to manufacture uniformly, the capacitor C1,
There was a variation in the electrostatic capacity of C2, which had to be adjusted later. Further, in order to form the movable electrode portion 2 and the beam 3 in the central portion of the silicon substrate in the thickness direction,
Manufacturing was difficult because complicated work such as high step photo etching of the thermal oxide film was required.

Next, the method of manufacturing the semiconductor capacitive acceleration sensor shown in FIG. 10 has the following problems.

The trench 1 is formed perpendicularly to the surface of the silicon substrate 8.
After forming No. 3, only the lower part of the trench 13 was anisotropically etched to form the mass part 10 and the cantilever 9. Therefore, it is difficult to confirm the end point when the cantilever 9 is etched, and the cantilever 9 having a constant size cannot be formed. Therefore, it is difficult to reproduce the accurate thickness dimension of the cantilever beam 9, and like the semiconductor capacitive acceleration sensor shown in FIG. 9, the displacement of the mass portion 10 due to the acceleration change is not stable, and the output variation. It was a factor.

Therefore, the present invention provides a small-sized semiconductor capacitance type acceleration sensor which can obtain a large differential output, and a manufacturing method for manufacturing the semiconductor capacitance type acceleration sensor accurately and easily.

[0016]

In order to achieve the above object, the semiconductor capacitive acceleration sensor of the present invention has the following structure and manufacturing method.

First, the semiconductor capacitive acceleration sensor has a groove formed on a semiconductor surface, a mass portion which is inserted into the groove and serves as a movable electrode supported by a beam, and a fixed portion formed on a side surface of the groove. An electrode and an extraction electrode connected to the fixed electrode and extracted on the insulating layer of the substrate, and the mass part is arranged in a state of floating in the groove.

Secondly, the semiconductor capacitive acceleration sensor has a groove formed on the semiconductor surface, a fixed electrode formed on the side surface of the groove, and a fixed electrode connected to the fixed electrode and drawn out on an insulating layer on the surface of the substrate. An extraction electrode, a mass part that is formed in the groove via a sacrificial film to serve as a movable electrode, and a beam that supports the mass part in the groove, and the mass part is formed by removing the sacrificial film. Is contactlessly supported in the groove.

Third, in the case of manufacturing a semiconductor capacitive acceleration sensor, a step of forming a groove in a semiconductor substrate having an insulating layer formed on the surface and a step of forming a fixed electrode made of an ion diffusion layer on the side surface of the groove. A step of forming a sacrificial layer with a uniform thickness on the side and bottom surfaces of the groove and the surface of the substrate; a step of forming a low-resistance elastic member on the sacrificial layer; It is manufactured by a step of forming a mass part and an electrode terminal, a step of forming an electrode after removing a part of the sacrificial layer, and a step of removing the remaining sacrificial layer.

Fourth, in the case of manufacturing the semiconductor capacitive acceleration sensor, in the manufacturing process of the semiconductor capacitive acceleration sensor described above, a step of forming a vertical groove continuous with the groove as if dividing the sidewall of the groove is included. It is manufactured by adding.

[0021]

Since the differential output of the semiconductor capacitive acceleration sensor is inversely proportional to the square of the electrode spacing, the narrower the electrode spacing, the larger. The fixed electrode uses the inner wall of the groove, and the mass part is used in combination with the movable electrode, and the electrode interval is as narrow as the film thickness, for example, several μm or less, so that a large differential output can be obtained. Further, since the distance between the fixed electrode and the mass portion can be determined by the film thickness of the sacrificial layer, it is possible to manufacture an accurate and narrow electrode distance without variation. That is, by removing the sacrificial layer, the electrode interval becomes an interval of the film thickness of the sacrificial layer, and the mass portion is supported by floating in the groove. Furthermore, forming a vertical groove along the groove facilitates removal of the sacrificial layer.

[0022]

【Example】

(Embodiment 1) An embodiment of the semiconductor capacitive acceleration sensor of the present invention will be described below with reference to FIGS. The semiconductor substrate 14 made of silicon has an insulating layer 1 made of silicon nitride.
5 is formed. Further, the semiconductor substrate 14 has a groove 16
And four vertical grooves slightly deeper than the groove 16 are provided.
In this embodiment, the rectangular column-shaped vertical groove 17 is illustrated. The rectangular column-shaped vertical groove 17 is formed continuously with the groove 16 at the four corners of the groove 16.

Impurity ions such as phosphorus, boron, and antimony are diffused on the side surface of the groove 16 so that they are electrically conductive. The side surface of the groove 16 is electrically divided by the rectangular column-shaped vertical groove 17, and the long side surface of the groove 16 is used as the fixed electrodes 18 and 19. Electrode lead portions 20A and 20B made of chromium gold or the like are formed from the upper portions of the fixed electrodes 18 and 19 to the insulating layer 15.

The movable electrode 21 made of low-resistance polycrystalline silicon is composed of a mass portion 22, a beam 23, and an electrode terminal 24. In the mass portion 22, a rectangular plate 22B is integrally formed on a rectangular parallelepiped 22A, and the cross section in the short side direction is T-shaped. The thickness of the beam 23 is a square plate 22B.
The width is about half the thickness, and the cross section is in the form of an elongated rectangular plate having a vertically long rectangular shape. The portion connected to the electrode terminal 24 is bent downward to form a curved portion 23A. Beam 23
Has a vertically long rectangular shape, and thus is displaced in the short side direction of the mass portion 22 to a greater extent than in other directions.
The electrode terminal 24 is, for example, a rectangular plate having the same thickness as the rectangular plate 22B, and an electrode 25 made of a metal such as chrome gold is formed on the upper surface. The beam 23 is a square plate 22B.
The beam 23 and the square plate 22 on both end faces in the long side direction of the
They are joined so that the center plane of B in the long side direction coincides. Further, the other end of the curved beam 23 is connected to the side surface of the electrode terminal 24. Movable electrode 2 formed in this way
1 has a symmetrical shape.

In FIG. 1, the semiconductor substrate 14 is illustrated for convenience of explanation.
Although the movable electrode 21 and the movable electrode 21 are shown as separate bodies, the semiconductor substrate 14 and the movable electrode 21 are actually the insulating layers on both sides of the short side of the groove 16 on the lower surface of the electrode terminal 24 as shown in FIG. It is made in one with 15. With the movable electrode 21 inserted in the groove 16, the long side surface of the rectangular parallelepiped 22A and the fixed electrodes 18, 19 are formed.
Are spaced by several μm or less, and the mass portion 22 is supported by the beam 23 and floats in the groove 16. The beam 23 is separated from the surface of the substrate 14 by the curved portion 23A. As described above, the semiconductor capacitive acceleration sensor including the two capacitors formed by the movable electrode 21 and the fixed electrodes 18 and 19 has a symmetrical shape in the short side direction and the long side direction.

When acceleration is applied in the short side direction of the movable electrode 21, the beam 23 is bent and deformed in the short side direction, the movable electrode 21 is displaced, and the distance between the fixed electrodes 18 and 19 is changed. Along with this, the electric capacities of the two capacitors change, and this change is taken out as a differential output.

Next, the outline of the manufacturing method of the present invention will be described with reference to FIGS. As shown in FIG. 3A, a groove 16 having a width of about 10 μm and a depth of about 100 μm is formed in a silicon semiconductor substrate 14 having a silicon nitride insulating layer 15 formed on the surface thereof. The groove 16 is formed by removing a part of the insulating layer 15 and the semiconductor substrate 14 by using a vertical processing method such as RIE. When the surface of the semiconductor substrate 14 is the (110) plane, the insulating layer 15 is formed by RIE.
After removing the above, the groove 16 may be formed by anisotropic etching using an alkaline aqueous solution such as potassium hydroxide or hydrazine. By using these processing methods, it is possible to form fine and precise recesses.

The side surface and the bottom surface of the groove 16 are shown in FIG.
As described above, the impurity ion diffusion layer 26 is formed by thermally diffusing ions such as phosphorus, boron, and antimony. After this,
The impurity ion diffusion layer 26 on the bottom surface of the groove 16 is removed by RIE as shown in FIG. The impurity ion diffusion layer 26 on this side surface serves as a fixed electrode in the groove 16.

Next, LPCVD (Low Pressu)
re CVD) method, as shown in FIG.
The sacrificial layer 27 is formed. The sacrificial layer 27 is provided with a uniform thickness on the side surface and the bottom surface of the groove 16 and the surface of the insulating layer 15.
This sacrificial layer 27 can be easily removed by chemical etching, such as PSG (phosphorus-silicon glass) and BPSG (boron-).
Phosphorus-silicon glass) or the like is used.

Since the electrode terminals 24 are formed on the surface of the semiconductor substrate 14 on the short side of the groove 16, the electrode terminal recesses 28 are formed as shown in FIG. 4 (e). That is, the insulating layer 15 is formed by chemical etching using a photoresist method or the like.
The sacrificial layer 27 is removed until appears. Chemical agents such as diluted hydrofluoric acid are used for the chemical etching. As a result of the chemical etching, the surface edge portion of the electrode terminal recess 28 is not right-angled but rounded, and the end portion of the beam 23 is formed into a curved shape.

Next, as shown in FIG. 4F, a low resistance polycrystalline silicon film is formed by LPCVD on the entire surface of the substrate to form a low resistance polycrystalline silicon portion 29.
The low-resistance polycrystalline silicon portion 29 includes a portion 29A that fills the space of the groove 16 and the layered portion 2 having a uniform thickness provided on the surface.
9B and 9B. However, the low resistance polycrystalline silicon portion 29 on the surface of the electrode terminal recess 28 is recessed by the depth of the electrode terminal recess 28. The low resistance polycrystalline silicon portion 29 may be a metal member formed by metal plating.

Next, as shown in FIG. 5G, the low resistance polycrystalline silicon portion 29 on both sides of the long side surface of the groove 16 is RI.
After removal by E, the exposed sacrificial layer 27 is removed by chemical etching using a photoresist method or the like to form the lead electrode recess 30. Chemical etching is performed on the insulating layer 15
And the ion diffusion layer 2 provided on the long side surface of the groove 16
Repeat until 6 appears. The sacrificial layer 27 formed on the side surface and the bottom surface of the groove 16 has a small layer thickness, so that it is difficult for chemicals to enter, and the sacrificial layer 27 remains without being chemically etched.

As shown in FIG. 5 (h), chromium gold or the like is vapor-deposited to form the electrode lead-out portion 20 from the insulating layer 15 on the bottom surface of the lead-out electrode recess 30 to the upper side of the long side of the groove 16.
In order to form the electrode lead-out portion 20 on the upper side surface 16A of the groove 16, oblique vapor deposition is performed. At the same time, chrome gold or the like is vapor-deposited on the low resistance polycrystalline silicon portion 29 at the position of the electrode terminal recess 28 to form the electrode 25.

Next, as shown in FIG. 5 (i), the low resistance polycrystalline silicon portion 29 includes a mass portion 22, a beam 23, and an electrode 2.
5 is removed by a vertical processing method such as RIE, leaving the electrode terminals 24 on the lower part. After that, the sacrificial layer 27 of the groove 16 is removed by chemical etching. However, since the sacrifice layer 27 formed on the side surface and the bottom surface of the groove 16 has a small layer thickness, the chemical agent remains without entering. Therefore, in FIG.
By performing the same vertical machining method as in (a), continuous vertical grooves slightly deeper than the groove 16 are formed at the four corners of the groove 16 as shown in FIG. 6 (j). In the embodiment, the rectangular column-shaped vertical groove 17
Is illustrated. By utilizing this rectangular column-shaped vertical groove 17 as a liquid summary of chemicals, the sacrificial layer 27 is formed as shown in FIG.
As shown in (k), the side surface on the long side in the groove 16 is electrically removed while being completely removed.

By manufacturing the semiconductor capacitive acceleration sensor as described above, the distance between the fixed electrodes 18 and 19 and the mass portion 22 can be formed uniformly with the thickness of the sacrificial layer 27, for example, several μm or less. it can.

(Embodiment 2) Another embodiment of the semiconductor capacitive acceleration sensor of the present invention will be described below with reference to FIGS. 7 and 8. The same parts as those in the first embodiment are denoted by the same reference numerals, and the manufacturing method is the same as that in the first embodiment, and therefore the description thereof is omitted.

An elongated groove 16 is formed in the semiconductor substrate 14, and rectangular longitudinal grooves 31 slightly deeper than the groove 16 are formed continuously on both sides of the groove 16 on both sides in the longitudinal direction. .

Impurity ions such as phosphorus, boron, antimony, etc. are diffused on the side surface of the groove 16 and are electrically conductive. The side surface of the groove 16 is electrically divided by the rectangular vertical groove 31, and the long side surface of the groove 16 is used as the fixed electrodes 18 and 19. An electrode lead portion 20 made of chrome gold or the like is formed from the upper portions of the fixed electrodes 18 and 19 to the insulating layer 15.

The movable electrode 21 made of low-resistance polycrystalline silicon is composed of a mass portion 22, a beam 23, and an electrode terminal 24. The mass portion 22 has a rectangular parallelepiped shape. The beam 23 is in the shape of a rectangular elongated plate having a laterally long cross section having a width twice or more the thickness, and the portion connected to the electrode terminal 24 is bent downward. The electrode terminal 24 is a beam 23.
It is a square plate having the same thickness as the above, and an electrode 25 made of a metal such as chrome gold is formed on the upper surface. Beam 23
Indicates that the length direction of the beam 23 coincides with the short side direction of the mass part 22 at the four upper end portions on the long side surface of the mass part 22 in the figure, and the upper surfaces of the beam 23 and the mass part 22 in the figure are the same. It is connected so that it may become a plane. Further, the other end of the curved beam 23 is connected to the side surface of the electrode terminal 24. The movable electrode 21 thus formed has an H-shaped bilaterally symmetrical shape.

In FIG. 7, the semiconductor substrate 14 is shown for convenience of explanation.
And the movable electrode 21 are shown as separate bodies. However, in reality, as shown in FIG. 8, the semiconductor substrate 14 and the movable electrode 21 are
Are integrally formed with the insulating layer 15 on the lower surface of the electrode terminal 24. With the movable electrode 21 inserted in the groove 16,
The long side surface of the rectangular parallelepiped 22A and the fixed electrodes 18 and 19 are spaced apart from each other by a thickness of the sacrifice layer 27 of several μm or less.
Is supported by the four beams 23 and floats in the groove 16. In this way, the movable electrode 21 and the fixed electrode 18,
The semiconductor capacitive acceleration sensor having two capacitors formed by 19 has a symmetrical shape in both the short side direction and the long side direction.

When acceleration is applied in the short side direction of the movable electrode 21, the beam 23 is bent and deformed, whereby the movable electrode 21 is displaced and the distance between the fixed electrodes 18 and 19 is changed. In this case, since the beam 23 is not in contact with the surface of the substrate 14, the exercise load of the mass portion 22 is small. Along with this, the electric capacities of the two capacitors change, and this change is taken out as a differential output.

Although the groove 16 viewed from the surface of the substrate 14 has a rectangular shape in the above embodiment, it may have a square shape, a circular shape, an elliptical shape or the like, but the areas of the fixed electrodes 18 and 19 are increased. From the viewpoint, a rectangle is desirable. In order to increase the area of the fixed electrodes 18 and 19, the shape of the groove 16 may be a cross shape or an H shape. Further, as the means for electrically disconnecting the fixed electrodes 18 and 19 in the groove 16, four rectangular column-shaped vertical grooves 17 are provided, but the object can be achieved with two. A laser beam or anisotropic wet etching may be used as a means. Further, in the manufacturing method, the mass portion 22, the beam 23, and the electrode terminal 24 may be formed in the step of forming the recessed portion 30 for the extraction electrode of FIG. It goes without saying that a photoresist is used for this processing.

[0043]

The present invention has the following effects due to the above-described structure and manufacturing method.

(1) Since the electrode gap between the fixed electrode and the mass portion of the acceleration sensor is extremely small, ie, several μm or less, a large differential output can be obtained. Therefore, the detection sensitivity of the semiconductor capacitive acceleration sensor is improved. Further, since the differential output is large, the differential output more than the conventional one can be obtained even if the electrode area of the capacitor is reduced, so that the size can be reduced.

(2) Since the connecting portion between the beam and the electrode terminal forms a curved portion and lifts the beam from the substrate surface, the mass portion sensitively detects motion even with a small acceleration, and an acceleration sensor with high detection sensitivity is provided. can get.

(3) In the method of manufacturing the acceleration sensor,
Since the electrode spacing is set by the thickness of the sacrificial layer, a narrow electrode spacing can be manufactured accurately and uniformly, the yield at the time of manufacturing is increased, and the variation in electrostatic capacitance is reduced,
There is no need for adjustment in the subsequent process. That is, the acceleration sensor output can be increased by the film thickness of the sacrificial layer, and a highly sensitive acceleration sensor can be obtained. Moreover, since the thickness direction of the substrate is mainly used, the area of the acceleration sensor can be reduced, and more acceleration sensors can be manufactured from one silicon wafer.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a semiconductor capacitive acceleration sensor of the present invention.

FIG. 2 is an assembled perspective view of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 3 is a schematic view of the manufacturing process of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 4 is a schematic view of the manufacturing process of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 5 is a schematic view of the manufacturing process of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 6 is a schematic view of the manufacturing process of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 7 is an exploded perspective view of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 8 is an assembled perspective view of the semiconductor capacitive acceleration sensor of the present invention.

FIG. 9 is a sectional view of a conventional semiconductor capacitive acceleration sensor.

FIG. 10 is a cross-sectional view of a conventional semiconductor capacitive acceleration sensor.

[Explanation of symbols]

 2 movable electrode part 3 beam 6, 7 fixed electrode 9 cantilever beam 10 mass part 12 electrode 13 trench 14 semiconductor substrate 15 insulating layer 16 groove 17 square pillar-shaped vertical groove 18, 19 fixed electrode 20A, 20B electrode lead-out part 21 movable electrode 22 Mass part 23 Beam 24 Electrode terminal 25 Electrode 26 Impurity ion diffusion layer 27 Sacrificial layer 28 Recess for electrode terminal 29 Low resistance polycrystalline silicon part 30 Recessed electrode recess 31 Rectangular groove

Claims (4)

[Claims] 1. A groove formed on a surface of a semiconductor, and a mass portion inserted into the groove and supported by a beam to serve as a movable electrode,
A fixed electrode formed on the side surface of the groove, and an extraction electrode connected to the fixed electrode and extracted on the insulating layer of the substrate,
A semiconductor capacitive acceleration sensor characterized in that a mass part is arranged in a state of being floated in a groove. 2. A groove formed on a semiconductor surface, a fixed electrode formed on a side surface of the groove, an extraction electrode connected to the fixed electrode and extracted on an insulating layer on a substrate surface, and the inside of the groove. A mass part which is formed through a sacrificial film and serves as a movable electrode, and a beam which supports the mass part in the groove, and the mass part is supported in the groove without contact by removing the sacrificial film. A semiconductor capacitive acceleration sensor characterized by the above. 3. A step of forming a groove in a semiconductor substrate having an insulating layer formed on the surface, a step of forming a fixed electrode made of an ion diffusion layer on the side surface of the groove, and a sacrificial layer on the side surface and bottom surface of the groove and the substrate surface. A uniform thickness, a step of forming a low-resistance elastic member on the sacrificial layer, a step of removing a part of the low-resistance elastic member to form a beam, a mass part, and an electrode terminal, and a sacrificial layer. And a step of removing the remaining sacrificial layer, and a step of removing the remaining sacrificial layer, and a method of manufacturing a semiconductor capacitive acceleration sensor. 4. The method of manufacturing a semiconductor capacitive acceleration sensor according to claim 3, further comprising the step of forming a vertical groove continuous with the groove so as to divide the side wall of the groove.