JP2002202318A - Semiconductor dynamic quantity sensor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the sensitivity irregularity caused by the irregularity of electrostatic capacity between a movable electrode and a fixed electrode even if the control of the film thickness of a structure is insufficient. SOLUTION: A support part (base plate part 3 + square frame part 5), a beam structure 6 and fixed electrodes 16b and 22b are demarcated by the cavity 2 formed to a silicon substrate 1 to extend in a lateral direction and the grooves 4a and 4b formed to the silicon substrate 1 to extend in a longitudinal direction. The fixed electrodes 16b and 22b are opposed to the movable electrode of the beam structure. Dielectric membranes 40 and 41 also function as protective films at the time of etching of the substrate for forming the cavity 2 to the side walls of the movable electrode and the fixed electrodes 16b and 22b. The membranes 40 and 41 contain at least either one of silicon nitride, aluminum oxide, calcium fluoride, zirconium oxide, tantalum oxide and cerium oxide as a dielectric material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor dynamic quantity sensor having a beam structure having a movable electrode and detecting a dynamic quantity such as acceleration, yaw rate, vibration, and the like.

[0002]

2. Description of the Related Art Conventionally, as this type of sensor structure, there is one disclosed in Japanese Patent Application Laid-Open No. 2000-286430. This sensor will be described with reference to a plan view of FIG. 11 and a longitudinal sectional view of FIG. A base plate portion 10 is provided below a laterally extending cavity 101 formed in a silicon substrate 100.
2, a rectangular frame 104, a beam structure 106 having a movable electrode 105, and a fixed electrode 107 are defined by the cavity 101 and the groove 103 extending in the vertical direction. The fixed electrode 107 is a movable electrode 105 of the beam structure 106.
And is facing. Further, the movable electrode 105 and the square frame 1
A groove 108 is formed between the fixed electrode 107 and the fixed frame 107 and the square frame 104, and an electrically insulating material 109 is embedded in the groove 108. Then, a capacitor is formed by the movable electrode 105 and the fixed electrode 107, and the acceleration can be detected based on a change in the capacitance of the capacitor.

At the time of manufacturing, as shown in FIG. 13, a groove 108 is formed on the upper surface of a silicon substrate 100 and is buried with an insulating material 109.
Trench 1 extending in the vertical direction for partitioning the rectangular frame portion, the beam structure, and the fixed electrode by performing anisotropic etching from the upper surface of
03 is formed, and the protective film 11 is
0 is formed. Then, as shown in FIG.
Isotropic etching is performed on the silicon substrate 100 from the bottom surface of the silicon substrate 100 to form a cavity 101 extending in the lateral direction. As a result, the base plate portion 102 located below the cavity 101
, Square frame 104, beam structure 106, fixed electrode 1
07 are formed.

[0004]

However, in the above-described isotropic etching of the semiconductor acceleration sensor in FIG. 14, the thickness of the beam structure 106 and the fixed electrode 107 can be controlled only by the etching time. Considering the in-plane variation of the etching, the thickness variation of the structure becomes extremely large, and the sensor chip in the wafer surface has a large difference (distribution) in the capacitance between movable and fixed electrodes.
May occur. Further, there is a possibility that a sensor cannot be manufactured with high reproducibility.

The present invention has been made in view of the above problems, and it is an object of the present invention to reduce a variation in sensitivity of a sensor caused by a variation in capacitance between a movable electrode and a fixed electrode even when the structure thickness control is insufficient. With the goal.

[0006]

According to a first aspect of the present invention, there is provided a semiconductor dynamic quantity sensor, wherein a dielectric thin film also functions as a protective film at the time of etching a substrate for forming a cavity on a side wall of a movable electrode and a fixed electrode. And the thin film contains at least one of silicon nitride, aluminum oxide, calcium fluoride, zirconium oxide, tantalum oxide, and cerium oxide as a dielectric material. As a result, even if the thickness of the structure (movable electrode, fixed electrode) varies due to isotropic etching of the semiconductor substrate, the variation in capacitance is caused by the dielectric thin film left in the opposing portion. Reduced. More specifically, as the thickness of the structure (electrode) decreases from a desired value, the capacitance decreases accordingly. However, if the dielectric thin film remains, the dielectric film is wrapped around from the bottom portion of the structure (electrode). The capacitance increases, and the reduced capacitance at the opposing portion can be replenished. In this way, even if the control of the thickness of the structure is insufficient, the variation in the capacitance between the movable electrode and the fixed electrode can be suppressed, and the variation in the sensitivity of the sensor can be reduced.

In particular, if silicon nitride is used as the dielectric material of the dielectric thin film, an inexpensive sensor can be formed without using new capital investment by using a material usually used in a semiconductor manufacturing process. .

According to the semiconductor dynamic quantity sensor according to the second aspect, the deformation of the structure caused by the stress of the dielectric thin film can be reduced. According to the semiconductor dynamic quantity sensor according to the third aspect, it is possible to prevent the dielectric thin film from being in contact with the facing electrode and restricting the movable range, thereby inhibiting the function as the sensor.

According to the semiconductor dynamic quantity sensor of the fourth aspect, a silicon oxide film is generally known as a film having a compressive stress, and a silicon nitride film is known as a film having a tensile stress, and is generally used in a semiconductor manufacturing process. By forming a mixture of materials, an inexpensive sensor can be formed without requiring new capital investment.

[0010] According to the semiconductor dynamic quantity sensor according to the fifth aspect, the deformation of the structure caused by the stress of the dielectric thin film can be reduced by balancing the compression and the tension. According to the semiconductor physical quantity sensor according to the sixth aspect, a silicon oxide film is generally known as a film having a compressive stress, and a silicon nitride film is known as a film having a tensile stress, and a material usually used in a semiconductor manufacturing process is used. by doing,
Inexpensive sensors can be formed without requiring new capital investment.

According to the semiconductor physical quantity sensor according to the present invention, it is possible to provide a sensor excellent in temperature characteristics by reducing deformation caused by a difference in thermal expansion coefficient between the dielectric thin film and the structure.

According to the semiconductor physical quantity sensor of the present invention, the thickness of the dielectric thin film is 100 nm or more, and the structure (movable electrode, fixed electrode) in a part of the dielectric thin film disappears. In such a portion, it is possible to prevent peeling, particle formation in the manufacturing process, breakage during use, and the like.

According to the semiconductor dynamic quantity sensor according to the ninth aspect, by using a substrate most commonly used in a semiconductor manufacturing process, an inexpensive sensor can be formed without requiring new capital investment.

According to the method for manufacturing a semiconductor dynamic quantity sensor according to the tenth aspect, the semiconductor dynamic quantity sensor according to the first to ninth aspects can be manufactured, and further, the dielectric thin film is formed by film formation for each atomic layer. By doing so, a film can be formed with a uniform film thickness.

According to the method of manufacturing a semiconductor dynamic quantity sensor according to the eleventh aspect, the thickness of the dielectric thin film is reduced by using an atomic layer epitaxy method when forming a film for each atomic layer. With good controllability, a method of manufacturing a semiconductor dynamic quantity sensor can be provided in which a difference in a film formation rate between a shallow portion and a deep portion, which is a problem when forming a film in a groove, is eliminated.

According to a twelfth aspect of the present invention, in the semiconductor physical quantity sensor, a conductive thin film which also functions as a protective film at the time of etching a substrate for forming a cavity is formed on the side walls of the movable electrode and the fixed electrode. And Thus, even if the thickness of the structure (the movable electrode or the fixed electrode) varies, the variation of the capacitance is reduced by the conductive thin film left on the opposing portion. More specifically, when the thickness of the structure (electrode) decreases from a desired value, the capacitance decreases accordingly. However, when the conductive thin film remains, the structure itself functions as a counter electrode and becomes static. This is because capacitance is formed. In this way, even if the control of the thickness of the structure is insufficient, the variation in the capacitance between the movable electrode and the fixed electrode can be suppressed, and the variation in the sensitivity of the sensor can be reduced.

According to the semiconductor dynamic quantity sensor according to the present invention, if a metal such as aluminum is used, a sufficient selectivity can be obtained when the semiconductor substrate is isotropically etched. The conductive thin film does not disappear in the manufacturing process.

According to the semiconductor dynamic quantity sensor according to the present invention, it is possible to prevent the conductive thin film from contacting the opposing electrode to restrict the movable range or to electrically short-circuit. According to the semiconductor dynamic quantity sensor according to claim 18,
The deformation of the structure caused by the stress of the conductive thin film can be reduced.

According to the semiconductor physical quantity sensor of the nineteenth aspect, the deformation of the structure caused by the stress of the conductive thin film can be reduced by balancing the compression and the tension.

According to the semiconductor dynamic quantity sensor of the present invention, it is possible to provide a sensor having excellent temperature characteristics by reducing deformation caused by a difference in thermal expansion coefficient between the conductive thin film and the structure.

According to the semiconductor dynamic quantity sensor according to the twenty-first aspect, the conductive thin film has a thickness of 100 nm or more, and the structure (movable electrode, fixed electrode) in a part of the conductive thin film disappears. In such a portion, it is possible to prevent peeling, particle formation in the manufacturing process, breakage during use, and the like.

By using a substrate most commonly used in a semiconductor manufacturing process, an inexpensive sensor can be formed without requiring new capital investment.

As described in the twenty-third aspect, if the structure and the conductive thin film are in ohmic contact, the structure also becomes a path for an electric signal and the resistance is reduced, so that a measurement with higher response can be performed.

According to the method of manufacturing a semiconductor dynamic quantity sensor according to claim 24, the semiconductor dynamic quantity sensor according to any one of claims 12 to 23 can be manufactured, and the conductive thin film can be formed for each atomic layer. By forming the film, a conductive thin film can be formed uniformly.

According to the method for manufacturing a semiconductor dynamic quantity sensor according to the twenty-fifth aspect, the thickness of the conductive thin film can be reduced by using an atomic layer epitaxy method when forming a film for each atomic layer. The method of manufacturing a semiconductor dynamic quantity sensor excellent in uniformity of film thickness by eliminating the difference in film formation rate between a shallow portion and a deep portion, which is problematic when forming a film in a groove, can be provided.

According to the method of manufacturing a semiconductor dynamic quantity sensor according to the twenty-sixth aspect, an ohmic contact between the conductive thin film and the movable electrode / fixed electrode can be obtained, the overall resistance can be reduced, and a high frequency can be obtained. It will be possible to respond to the measurement method used.

According to a twenty-seventh aspect of the present invention, there is provided a semiconductor dynamic quantity sensor, wherein an electrode for controlling or maintaining a constant electric potential of a supporting portion is provided on a semiconductor substrate. Therefore, the support portion can be fixed at a desired potential, noise and the like caused by the potential of the support portion can be reduced, and more accurate sensing can be performed. In this way,
Even if the structure thickness control is insufficient, it is possible to reduce the variation in the sensitivity of the sensor due to the variation in the capacitance between the movable electrode and the fixed electrode.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an acceleration sensor according to this embodiment. FIG. 1 is a plan view of the acceleration sensor,
FIG. 2 is a perspective view of the acceleration sensor. FIG. 3 shows a cross section taken along line AA in FIG. 1, and FIG. 4 shows a cross section taken along line BB in FIG.

FIG. 5 is a perspective view in a state where the wiring of the acceleration sensor is removed. In other words, FIG. 2 is a perspective view including the wiring of the present sensor, whereas FIG.

In FIG. 3, a cavity 2 is formed inside a silicon substrate 1 as a single-layer semiconductor substrate, the cavity 2 has a predetermined thickness t, and has a lateral direction (horizontal direction). Extends to. A portion of the substrate 1 below the cavity 2 is a base plate portion 3. That is, the base plate 3 is defined by the cavity 2, and the base plate 3 is located below the cavity 2. Also, at a portion of the substrate 1 above the cavity 2, as shown in FIGS.
a, 4b, 4c, 4d are formed, and the grooves 4a to 4d extend in the vertical direction and reach the cavity 2. This cavity 2
As shown in FIG. 5, the rectangular frame portion 5 and the beam structure 6 are defined by the grooves 4a to 4d. The rectangular frame portion 5 is located beside the cavity 2 and the grooves 4a and 4b, and stands upright on the upper surface of the base plate portion 3. This square frame part 5
Are constituted by the side walls of the substrate 1. In addition, beam structure 6
Is located above the cavity 2 and extends from the square frame 5.
At this time, the beam structure 6 is disposed at a predetermined interval t from the upper surface of the base plate 3. Furthermore, cavity 2
The fixed electrodes 16a to 16d,
17a to 17d, 22a to 22d, and 23a to 23d are defined, and these fixed electrodes are located above the cavity 2 and extend from the rectangular frame 5.

In this embodiment, the base plate 3 and the rectangular frame 5 constitute a support for supporting the beam structure and the fixed electrodes. In FIG. 5, the beam structure 6 includes anchor portions 7 and 8, beam portions 9 and 10, and a mass portion 1.
1 and movable electrodes 12a, 12b, 12c, 12d, 13
a, 13b, 13c, and 13d. Square frame part 5
The anchor portions 7 and 8 project from the opposing inner wall surfaces of the above, and a mass portion 11 is connected and supported to the anchor portions 7 and 8 via beams 9 and 10. That is, the mass part 11
Is installed by the anchor portions 7 and 8 inside the square frame portion 5 and is disposed at a position on the upper surface of the base plate portion 3 at a predetermined interval t.

Insulating grooves 14a and 14b are formed between the anchor portions 7 and 8 and the beam portions 9 and 10, and electrically insulating materials 15a and 15b such as oxide films are disposed therein. It is electrically insulated at 15a and 15b.

Four movable electrodes 12a to 12d protrude from one side surface of the mass portion 11. Also, four movable electrodes 13a are provided from the other side surface of the mass portion 11.
To 13d protrude. Movable electrodes 12a to 12d, 1
3a to 13d have a comb shape extending in parallel at equal intervals. As described above, the beam structure 6 includes the movable electrodes 12a to 12d and 13a which are displaced by acceleration which is a mechanical quantity.
~ 13d.

In FIG. 5, the first fixed electrodes 16a, 16b, 16c, 16d and the second fixed electrodes 17a, 17b, 17c are provided on the inner wall surface of the rectangular frame portion 5 facing the movable electrodes 12a to 12d. , 17d are fixed. The first fixed electrodes 16a to 16d are arranged on the upper surface of the base plate portion 3 at a predetermined interval t, and face one side surface of the movable electrodes 12a to 12d. Similarly, the second fixed electrodes 17a to 17d are arranged on the upper surface of the base plate portion 3 at a predetermined interval t, and face the other side surfaces of the movable electrodes 12a to 12d. Here, insulating grooves 18a to 18d (see FIG. 3) are formed between the first fixed electrodes 16a to 16d and the square frame portion 5, and inside the insulating grooves 18a to 18d are electrically insulating materials 19a to 19d such as oxide films.
(See FIG. 3), and the insulating materials 19a to 19d
Is electrically insulated. Similarly, between the second fixed electrodes 17a to 17d and the square frame portion 5, insulating grooves 20a to 20d are provided.
20d (see FIG. 4) is formed, and electrically insulating materials 21a to 21d (see FIG. 4) such as an oxide film are disposed therein, and are electrically insulated by the insulating materials 21a to 21d.

Similarly, in FIG. 5, on the surface of the inner wall surface of the square frame portion 5 facing the movable electrodes 13a to 13d,
The first fixed electrodes 22a, 22b, 22c, 22d and the second fixed electrodes 23a, 23b, 23c, 23d are fixed. The first fixed electrodes 22a to 22d are arranged on the upper surface of the base plate portion 3 at a predetermined interval t, and face one side surface of the movable electrodes 13a to 13d. Similarly, the second fixed electrodes 23a to 23d are arranged on the upper surface of the base plate section 3 at positions separated by a predetermined interval t, and face the other side surfaces of the movable electrodes 13a to 13d. Here, insulating grooves 24a to 24d (see FIG. 3) are formed between the first fixed electrodes 22a to 22d and the square frame portion 5, and inside the insulating grooves 24a to 24d are electrically insulating materials 25a to 25d such as oxide films.
25d (see FIG. 3), and the insulating materials 25a to 25d
It is electrically insulated at 25d. Similarly, an insulating groove 2 is provided between the second fixed electrodes 23 a to 23 d and the square frame 5.
6a to 26d (see FIG. 4) are formed, and electrical insulating materials 27a to 27d (see FIG. 4) such as an oxide film are disposed therein, and are electrically insulated by the insulating materials 27a to 27d. I have.

As described above, in the present embodiment, the insulating materials 15a, 15b,
19a to 19d, 21a to 21d, 25a to 25d, 2
The movable and fixed electrodes are connected to the square frame 5 through 7a to 27d.
And is electrically insulated from the base plate portion 3 side.

As shown in FIG. 2, the first fixed electrode 16a
In 16 to 16d, the potential is taken out to the outside by the wiring 28, and in the second fixed electrodes 17a to 17d, the potential is taken out to the outside by the wiring 29. Similarly, the potential of the first fixed electrodes 22a to 22d is extracted to the outside by the wiring 30, and the potential of the second fixed electrodes 23a to 23d is extracted to the outside by the wiring 31. More specifically, as shown in FIG. 3, the first fixed electrodes 16a to 16d, 22
From a to 22d, a potential is taken out to the outside while being electrically insulated from the rectangular frame portion 5 through the contact portions 34 and 35 by the wirings 28 and 30 formed on the oxide films 32 and 33. . Further, as shown in FIG. 4, the rectangular frame portion 5 is formed from the second fixed electrodes 17a to 17d and 23a to 23d through the contact portions 36 and 37 by the wirings 29 and 31 formed on the oxide films 32 and 33. The electric potential is extracted to the outside while keeping the electrical insulation.

As shown in FIG. 2, the movable electrode 12a
12d and 13a to 13d pass through the mass portion 11 and the beam portions 9 and 10, and are extracted to the outside by wirings 38 and 39 (specifically, through contact portions provided in the beam portions 9 and 10). ing.

On the other hand, the groove 4a formed in the silicon substrate 1
A dielectric thin film is formed on the side walls of 4d to 4d. Figure 3,
4, the mass 11 and the fixed electrodes 16b, 17a, 22
This shows a state in which a dielectric thin film is formed on each of the side walls b and 23a. That is, as shown in FIGS. 3 and 4, the dielectric thin film 40 is provided on the side wall of the
16d, 17a-17d, 22a-22d, 23a-2
Dielectric thin films 41 and 42 are formed on the 3d side wall, respectively.

A silicon nitride film is used as the dielectric thin films 40, 41, and 42, and has a higher dielectric constant than air. As a dielectric material of the thin films 40, 41, and 42, in addition to silicon nitride, Al ₂ O ₃ , CaF ₂ , ZrO ₂ , TaO ₅ ,
CeO ₂ may be used. Further, the dielectric thin films 40, 4
Since a smaller residual stress can prevent the movable electrode and the fixed electrode from being deformed, the layers 1 and 42 may be formed by laminating a silicon nitride film having a tensile stress and a silicon oxide film having a compressive stress. The stress may be reduced by controlling the composition ratio of oxygen and nitrogen as the SiON film. Furthermore, if the movable electrode and the fixed electrode are dielectric thin films having similar thermal expansion coefficients, the generation of stress caused by a temperature change can be suppressed, and the electrodes will not be deformed.

Further, with respect to the dielectric thin films 40, 41, and 42, the portions protruding from the electrode side walls toward the base plate portion 3 (downward) have no movable electrode or fixed electrode, so that the structural strength is greatly reduced. . For this reason, it may be damaged during the manufacturing process and during use. Furthermore, warping or peeling may occur in severe cases due to the stress distribution in the film thickness direction of the dielectric thin film itself. In order to solve these problems, it is effective to increase the thickness of the film, and preferably 100 nm or more.

On the other hand, on the upper surface of the substrate 1 (in FIGS. 3 and 4,
Square frame part 5, mass part 11, fixed electrodes 16a to 16d, 1
7a to 17d, 22a to 22d, and 23a to 23d), the oxide films 32 and 33 are formed as described above.

As described above, in the semiconductor acceleration sensor according to the present embodiment, as shown in FIGS. 3 and 4, the base plate portion 3 is partitioned by the cavity 2, and the rectangular frame portion 5 is formed by the cavity 2 and the groove 4.
a, 4b, the movable electrodes 12a to 12d, 1
Beam structure 6 having 3a to 13d includes cavity 2 and groove 4a
4d, and fixed electrodes 16a to 16d, 17
a to 17d, 22a to 22d, and 23a to 23d are hollow 2
And the grooves 4a and 4b. Groove 1
4a, 14b, 18a to 18d, 20a to 20d, 24
a to 24d and 26a to 26d are movable electrodes 12a to 12d.
d, 13a to 13d and the rectangular frame 5 and fixed electrodes 16a to 16d, 17a to 17d, 22a to 22d, 2
3a to 23d and the rectangular frame portion 5, and electrically insulating materials 15a, 15b, 19a to 19d, 21a to 21
d, 25a to 25d and 27a to 27d are embedded.

Therefore, the cavity 2 formed in the silicon substrate 1
Base plate portion 3 and square frame portion 5 by means of grooves 4a to 4d.
And beam structure 6 and fixed electrodes 16a to 16d and 17a to 17
d, 22a to 22d, and 23a to 23d, and between the movable electrodes 12a to 12d, 13a to 13d and the rectangular frame 5, and to the fixed electrodes 16a to 16d, 17a.
Grooves 14a, 14b, 18a-18 formed between the rectangular frame portion 5 and the square frame portion 5-17d, 22a-22d, 23a-23d.
d, 20a to 20d, 24a to 24d, 26a to 26d
Electrically insulating materials 15a, 15b, 19a embedded in
~ 19d, 21a ~ 21d, 25a ~ 25d, 27a ~
The electrodes are electrically separated by 27d.

As described above, in a semiconductor dynamic quantity sensor in which a beam structure having a movable electrode and a fixed electrode opposed to the movable electrode are formed on one silicon substrate,
Since a single-layer semiconductor substrate, that is, a single-crystal silicon substrate 1 is used, the cross-sectional structure of the sensor can be simplified.

Next, the operation of the acceleration sensor configured as described above will be described with reference to FIG. Movable electrode 12a
A first capacitor is formed between the movable electrodes 12a to 12d and the first fixed electrodes 16a to 16d, and a second capacitor is formed between the movable electrodes 12a to 12d and the second fixed electrodes 17a to 17d. ing. Similarly, the movable electrodes 13a to 13d
A first capacitor is formed between the first and second fixed electrodes 22a to 22d, and a second capacitor is formed between the movable electrodes 13a to 13d and the second fixed electrodes 23a to 23d.

Here, the movable electrodes 12a to 12d (13a
To 13d) are fixed electrodes 16a to 16d (22a) on both sides.
22d) and 17a to 17d (23a to 23d), the capacitances C1 and C2 between the movable electrode and the fixed electrode.
Are equal. The movable electrodes 12a to 12d (13a to 1
3d) and the fixed electrodes 16a to 16d (22a to 22d), the voltage V1 is applied to the movable electrodes 12a to 12d (13a to 1d).
Voltage V2 is applied between 3d) and fixed electrodes 17a to 17d (23a to 23d).

When no acceleration occurs, V1 = V
2 and the movable electrodes 12a to 12d (13a to 13d)
Are fixed electrodes 16a to 16d (22a to 22d) and 17
a to 17d (23a to 23d) with the same electrostatic force.

Then, the acceleration acts in a direction parallel to the surface of the substrate 1, and the movable electrodes 12a to 12d (13a to 13d)
When d) is displaced, the distance between the movable electrode and the fixed electrode changes, and the capacitances C1 and C2 become unequal.

At this time, for example, the movable electrodes 12a to 12d
(13a to 13d) are fixed electrodes 16a to 16d (22a
２２22d), the capacitances C1 and C2
The voltages V1 and V2 are externally controlled so that the voltages V1 and V2 become equal. In this case, the voltage V1 is decreased and the voltage V2 is increased. Thereby, the fixed electrodes 17a to 17d (23a to
The movable electrodes 12a to 12d (13a to 13d)
d) is subtracted.

The movable electrodes 12a to 12d (13a to 13
If d) returns to the center position and the capacitances C1 and C2 become equal, the acceleration and the electrostatic force are equally balanced, and the magnitude of the acceleration can be obtained from the voltages V1 and V2 at this time.

As described above, in the first capacitor and the second capacitor, with respect to the displacement caused by the action of the acceleration,
The voltage of the fixed electrode forming the first and second capacitors is controlled so that the movable electrode is not displaced, and the acceleration is detected based on the change in the voltage. That is, it is a capacitance change detection type sensor.

Next, a method of manufacturing the acceleration sensor will be described with reference to the process diagrams shown in FIGS. In the description of the manufacturing process, the insulating structure (supporting structure) of each fixed electrode and beam structure is the same, so that the description of the other parts will be omitted by describing the BB cross section of FIG.

First, as shown in FIG. 6, a single-crystal silicon substrate 1 as a single-layer semiconductor substrate is prepared, and anisotropic etching is performed from the upper surface of the silicon substrate 1 to move the movable and fixed electrodes from the rectangular frame portion. First grooves 20a, 26a extending in the vertical direction for electrical insulation are formed by patterning. Then, a silicon oxide film is formed on the silicon substrate 1,
The grooves 20a and 26a are formed of insulating materials (oxide films) 21a and 27a.
And the substrate surface is covered with an oxide film 32.

Further, as shown in FIG.
Is formed and patterned, and then an oxide film 33 is formed to cover the wiring pattern 50. Subsequently, as shown in FIG. 8, the oxide films 32 and 3 on the substrate 1 and the wiring material 50 are formed.
3 is partially removed to form contact holes 36 and 37, and further, wiring materials 29 and 31 are formed and patterned.

Then, as shown in FIG. 9, a mask photo is formed on the silicon substrate 1 for forming a structure, and a mask 5 is formed.
In step 1, the oxide films 32 and 33 are etched. continue,
Anisotropic etching (trench etching) is performed from the upper surface of the silicon substrate 1 using the mask 51, and vertically extending grooves (second grooves) 4a for forming a square frame, a beam structure, and a fixed electrode are formed. 4b is formed. In FIG. 9, regions to be the mass part (11) and the fixed electrodes (17a, 23a) are formed. In addition, a silicon nitride film (dielectric thin film) which also protects the side walls prior to isotropic etching is provided on the inner wall surfaces (side surfaces and bottom surfaces) of the grooves 4a and 4b subjected to anisotropic etching during or after anisotropic etching. 40,
42 are formed, and the dielectric thin film on the bottom of the groove is removed. Thus, the dielectric thin films 40 and 42 are formed on the side walls of the grooves 4a and 4b except for the bottom surfaces of the grooves 4a and 4b.

The silicon nitride film as a dielectric material is suitable for a manufacturing process, and has a lower etching rate than silicon in isotropic etching of silicon performed in the next step. The wiring material is appropriately selected according to the method of forming the dielectric thin film to be employed, and the mask is devised.
That is, when the heat process is not applied, the wiring materials 29, 3
For 1, a metal wiring such as aluminum or a material such as polysilicon can be considered, and there is no problem even if a photoresist or the like is left for a mask for forming a structure. On the other hand, when a heat process is applied, the wiring materials 29 and 31 may be a material such as tungsten or a compound thereof, which is a high melting point metal, or polysilicon.
The photoresist or the like is peeled off, and a structure is formed using an oxide film mask.

Regarding the dielectric thin films 40 and 42, the dielectric material
Al instead of silicon nitride _TwoO_Three, CaF_Two,
ZrO_Two, TaO_Five, CeO_TwoWhen using
Atomic layer epitaxy (Atomic Layer)
Epitaxy) method is used. This atomic layer epitaxy method
By using this, the controllability of the thickness of the dielectric thin film is improved.
In addition, shallow portions and
Excellent film thickness uniformity by eliminating differences in deposition rates
Can provide an improved manufacturing method.

Returning to the description of the manufacturing process, next, as shown in FIG. 10, the silicon substrate 1 is isotropically etched from the bottom surfaces of the grooves 4a and 4b to form the cavity 2 extending in the lateral direction. Accordingly, a base plate portion 3 located below the cavity 2, a square frame portion 5 located beside the cavity 2 and the grooves 4a, 4b, a beam structure 6 having a movable electrode displaced by acceleration, and a beam structure The fixed electrodes 17a and 23a arranged opposite to the movable electrode 6 are sectioned. FIG.
At 0, only the silicon under the mass portion 11 and the fixed electrodes 17a and 23a is removed by etching. In particular, the mass portion 11 and the base plate portion 3 are completely separated from each other, and a predetermined interval t
Is formed.

In this isotropic etching, it is necessary to select a combination that does not etch the dielectric thin films 40 and 42 functioning as side wall protective films. In addition, in this isotropic etching, by using a plasma etching process using a gas material such as SF ₆ or CF ₄ , the yield of structure formation after etching is improved as compared with a wet process. Can be.

Finally, when the etching mask 51 is removed, the acceleration sensor shown in FIG. 4 can be formed.
Through these steps, a sensor can be formed which suppresses a change in capacitance due to a thickness variation of the structure (movable / fixed electrode) during isotropic etching.
That is, as shown in FIGS. 3 and 4, on the side walls of the movable electrode and the fixed electrode, dielectric thin films 40, 41, and 42 which also function as protective films at the time of substrate etching for forming the cavity 2 are formed. The thin films 40, 41, and 42 are made of at least silicon nitride, aluminum oxide,
Calcium fluoride, zirconium oxide, tantalum oxide,
By including any of the cerium oxide,
Even if the thickness of the structure (movable electrode, fixed electrode) varies due to isotropic etching of the silicon substrate 1, the dielectric thin films 40 to 42 protrude downward from the lower end of the side wall of the movable / fixed electrode. This variation (the dielectric thin films 40, 41, 42 left in the opposing portions) reduces variations in capacitance. More specifically, when the thickness of the structure (electrode) decreases from a desired value, the capacitance decreases accordingly, but when the dielectric thin films 40, 41, and 42 remain, the structure (electrode) starts from the bottom portion. , The capacitance increases due to the wraparound, and the capacitance reduced at the facing portion can be supplemented. As a result, even if the structure thickness control is insufficient, the capacitance between the movable electrode and the fixed electrode is prevented from being varied,
Variations in sensor sensitivity can be reduced. Also,
When silicon nitride is used as the dielectric thin films 40, 41, and 42, a material that is usually used in a semiconductor manufacturing process is used, so that a new sensor investment is not required and an inexpensive sensor can be formed.

In particular, when the residual stress of the dielectric thin films 40, 41, 42 is zero, the deformation of the structure caused by the stress of the dielectric thin films 40, 41, 42 can be reduced.
When the dielectric thin films 40, 41, and 42 extend in a direction that does not approach the opposing electrodes (just below in FIGS. 3 and 4), the dielectric thin films 40, 41, and 42 come into contact with the opposing electrodes. It is possible to prevent the function as a sensor from being blocked by restricting the movable range.

Further, when the dielectric thin films 40, 41 and 42 are composed of silicon, oxygen and nitrogen, a silicon oxide film is generally known as a film having a compressive stress, and a silicon nitride film is known as a film having a tensile stress. By forming a mixture of materials usually used in the manufacturing process, a new sensor investment is not required and an inexpensive sensor can be formed. Further, when the dielectric thin films 40, 41, 42 are formed of a material having a compressive stress and a material having a tensile stress, the deformation of the structure caused by the stress of the dielectric thin films 40, 41, 42 is balanced between compression and tension. Can be reduced. Further, when the dielectric thin films 40, 41, and 42 are a silicon oxide film and a silicon nitride film, a material that is usually used in a semiconductor manufacturing process is used, so that a new sensor investment is not required and an inexpensive sensor is formed. be able to.

If the dielectric thin films 40, 41, 42 have the same coefficient of thermal expansion as the movable electrode / fixed electrode, the difference in the coefficient of thermal expansion between the dielectric thin films 40, 41, 42 and the structure results. It is possible to provide a sensor having excellent temperature characteristics by reducing the resulting deformation. Further, the dielectric thin films 40, 41,
When the thickness of the layer 42 is set to 100 nm or more, peeling, particle formation in the manufacturing process, and the like in the part where the structure (movable electrode, fixed electrode) in a part of the dielectric thin film has disappeared.
Damage during use can be prevented.

On the other hand, the semiconductor substrate is a silicon substrate 1, and by using a substrate most commonly used in a semiconductor manufacturing process, an inexpensive sensor can be formed without requiring new capital investment.

Further, in the method of manufacturing the acceleration sensor,
If a method of forming a film for each atomic layer is used in the process of forming the dielectric thin films 40, 41, 42, the dielectric thin films 40, 41, 42
42 can be formed with a uniform film thickness. (Second Embodiment) Next, a second embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment. The second
This embodiment is similar to the dielectric thin films 40 to 42 described in the first embodiment, and a description of the same portions will be omitted, and the drawings will be described using the same components.

In this embodiment, a conductive thin film is formed on the side walls of the grooves 4a to 4d formed in the silicon substrate 1. 3 and 4, the mass 11 and the fixed electrode 16 are shown.
This shows a state in which conductive thin films are formed on the side walls of b, 17a, 22b, and 23a, respectively. That is, as shown in FIGS. 3 and 4, the conductive thin film 40 is
Fixed electrodes 16a to 16d, 17a to 17d, 22a to 2
The conductive thin films 41 and 42 are provided on the side walls of 2d and 23a to 23d.
Are formed respectively.

The conductive thin films 40, 41, and 42 may be formed by laminating a film having a compressive stress and a film having a tensile stress, since the smaller the residual stress, the more the deformation of the movable electrode and the fixed electrode can be prevented. Alternatively, the stress may be reduced by controlling the composition ratio. In addition, if the conductive thin film has a thermal expansion coefficient close to that of the movable electrode and the fixed electrode, it is possible to suppress the occurrence of stress caused by a temperature change, and the electrode is not deformed.

The lower surfaces of the movable electrode and the fixed electrode (silicon) of the conductive thin films 40, 41, and 42 are shaved by isotropic etching, and protrude from the electrode side walls toward the base plate portion 3 (downward). Parts are formed and the structural strength is greatly reduced. For this reason, it may be damaged during the manufacturing process and during use. Further, the stress distribution in the film thickness direction of the conductive thin films 40 to 42 itself may cause warpage or, in severe cases, peeling. In order to solve these problems, it is effective to increase the thickness of the film, and preferably 100 nm or more.

In many cases, the capacitance type sensor performs sensing by changing the voltage of a fixed electrode or the like at a frequency of several tens to several hundreds KHz called a carrier wave. Therefore, the lower the resistance of the fixed electrode and the movable electrode, the faster the electrical response, which is advantageous for sensing. For this purpose, the conductive thin films 40 to 4
It is desirable that the conductive thin films 40 to 42 and the movable electrode / fixed electrode be ohmic contacts so that the movable electrode / fixed electrode as well as the movable electrode / fixed electrode serve as a path for transmitting a signal.

In FIG. 5, a first capacitor is provided between the movable electrodes 12a to 12d and the first fixed electrodes 16a to 16d, and a first capacitor is provided between the movable electrodes 12a to 12d and the second fixed electrodes 17a to 17d. A second capacitor is formed between them. Similarly, a first capacitor is provided between the movable electrodes 13a to 13d and the first fixed electrodes 22a to 22d, and the movable electrodes 13a to 13d and the second fixed electrodes 23a to 23d.
A second capacitor is formed between the second capacitor and the capacitor 23d. The capacitances of these capacitors are the same as those of the conductive thin films 40 and 4 in FIG.
1 and between the conductive thin films 40 and 42 in FIG.

Next, a method of manufacturing the acceleration sensor will be described with reference to the process diagrams shown in FIGS. In the description of the manufacturing process, the insulating structure (supporting structure) of each fixed electrode and beam structure is the same, so that the description of the other parts will be omitted by describing the BB cross section of FIG.

First, as shown in FIG. 6, a single-crystal silicon substrate 1 as a single-layer semiconductor substrate is prepared, and anisotropic etching is performed from the upper surface of the silicon substrate 1 to move the movable and fixed electrodes from the rectangular frame portion. First grooves 20a, 26a extending in the vertical direction for electrical insulation are formed by patterning. Then, a silicon oxide film is formed on the silicon substrate 1,
The grooves 20a and 26a are formed of insulating materials (oxide films) 21a and 27a.
And the substrate surface is covered with an oxide film 32.

Further, as shown in FIG.
Is formed and patterned, and then an oxide film 33 is formed to cover the wiring pattern 50. Subsequently, as shown in FIG. 8, the oxide films 32 and 3 on the substrate 1 and the wiring material 50 are formed.
3 is partially removed to form contact holes 36 and 37, and further, wiring materials 29 and 31 are formed and patterned.

Then, as shown in FIG. 9, a mask photo is formed on the substrate 1 for forming a structure, and the oxide films 32 and 33 are etched with the mask 51. Then, the mask 5
1 is used to perform anisotropic etching (trench etching) from the upper surface of the silicon substrate 1 and vertically extending grooves (second grooves) 4a, 4b for forming a square frame, a beam structure, and a fixed electrode. To form In FIG. 9, the mass part (11)
In addition, a region to be the fixed electrode (17a, 23a) is formed. Also, conductive thin films 40 and 42 are formed on the inner wall surfaces (side surfaces and bottom surfaces) of the grooves 4a and 4b that have been subjected to anisotropic etching to protect the side walls prior to isotropic etching. The conductive thin film is removed. Thus, the conductive thin films 40 and 42 are formed on the side walls of the grooves 4a and 4b except for the bottom surfaces of the grooves 4a and 4b.

Here, the conductive thin films 40 and 42 must be selected to be suitable for the manufacturing process. That is, a conductive material having a lower etching rate than silicon in isotropic etching of silicon performed in the next step is selected. If a gas such as SF ₆ , CF, or XeF ₂ is used for the isotropic etching, a metal, a material containing a metal, a metal oxide, or a mixed material of a metal and silicon is preferable. Specifically, Al, Ni, Au, Cu, SnO ₂ ,
In ₂ O ₃ , ZnO, Al / Si and the like can be mentioned.

Further, by using an atomic layer epitaxy method for forming a film for each atomic layer, the thickness of the conductive thin films 40 and 42 can be controlled with good controllability. It is possible to provide a manufacturing method having excellent uniformity of film thickness by eliminating the difference in film formation rate between a shallow portion and a deep portion, which is a problem.

Returning to the description of the manufacturing process, next, as shown in FIG. 10, the silicon substrate 1 is isotropically etched from the bottom surfaces of the grooves 4a and 4b to form the cavity 2 extending in the lateral direction. Accordingly, a base plate portion 3 located below the cavity 2, a square frame portion 5 located beside the cavity 2 and the grooves 4a, 4b, a beam structure 6 having a movable electrode displaced by acceleration, and a beam structure The fixed electrodes 17a and 23a arranged opposite to the movable electrode 6 are sectioned. FIG.
At 0, only the silicon under the mass portion 11 and the fixed electrodes 17a and 23a is removed by etching. In particular, the mass portion 11 and the base plate portion 3 are completely separated from each other, and a predetermined interval t
Is formed.

In the isotropic etching, it is necessary to select a combination that does not etch the conductive thin films 40 and 42 functioning as the side wall protective films. In addition, at the time of this isotropic etching, SF ₆ or CF
By using a plasma etching process using a gas material such as _4, a structure formation yield after etching can be improved as compared with a wet process.

Finally, when the etching mask 51 is removed, the acceleration sensor shown in FIG. 4 can be formed.
Here, it is necessary to perform a heat treatment for making ohmic contact between the conductive thin films 40 and 42 and silicon (the movable electrode and the fixed electrode), but any heat treatment after the conductive thin film is formed may be used. However, it is necessary to perform the process at a temperature and for a time that does not cause any problem for the already formed wiring.

Through these steps, even if the thickness control of the structure during the isotropic etching is insufficient,
A sensor that can always secure a stable capacitance can be formed. That is, as shown in FIGS. 3 and 4, the conductive thin film 40, which also functions as a protective film at the time of etching the substrate for forming the cavity 2, is formed on the wall surfaces of the movable electrode and the fixed electrode.
By forming 41 and 42, the structure (movable electrode,
Even if the thickness of the fixed electrode varies, the conductive thin film 40
42 protrude downward from the lower end of the side wall of the movable / fixed electrode, and this portion (the conductive thin films 40, 41, 42 left in the opposing portions) reduces variation in capacitance. More specifically, when the thickness of the structure (electrode) decreases from a desired value, the capacitance decreases accordingly. However, if the conductive thin films 40, 41, and 42 remain, they themselves serve as the counter electrode. This is because it functions and forms a capacitance. As a result, even if the control of the thickness of the structure is insufficient, it is possible to suppress the variation in the capacitance between the movable electrode and the fixed electrode, and to reduce the variation in the sensitivity of the sensor.

In particular, the conductive thin films 40, 41, and 42 are preferably made of metal, a material containing a metal, a metal oxide, or a metal and silicon. For example, when a metal such as aluminum is used, a sufficient selectivity can be obtained when the silicon substrate 1 is isotropically etched.
0, 41, and 42 do not disappear.

When the residual stress of the conductive thin films 40, 41 and 42 is zero, the deformation of the structure caused by the stress of the conductive thin films 40 to 42 can be reduced. Further, when the conductive thin films 40, 41, and 42 are formed of a material having a compressive stress and a material having a tensile stress, deformation of a structure caused by the stress of the conductive thin films 40 to 42 is reduced by balancing compression and tension. can do.

When the conductive thin films 40, 41, and 42 have the same thermal expansion coefficient as the movable electrode and the fixed electrode, the deformation caused by the difference in the thermal expansion coefficient between the conductive thin films 40 to 42 and the structure. And a sensor having excellent temperature characteristics can be provided. Further, when the thickness of the conductive thin films 40, 41, 42 is 100 nm or more, the conductive thin films 40 to 42
In the part where the structure (movable electrode, fixed electrode) has disappeared, peeling, particle formation in the manufacturing process, breakage during use, and the like can be prevented.

Further, when the conductive thin films 40 to 42 are extended in a direction not approaching the opposing electrodes (just below in FIGS. 3 and 4), the conductive thin films 40 to 42 come into contact with the opposing electrodes and move. Limiting the range and preventing an electrical short circuit can be prevented.

On the other hand, the semiconductor substrate is the silicon substrate 1, and by using the substrate most commonly used in the semiconductor manufacturing process, an inexpensive sensor can be formed without requiring new capital investment. In addition, when the conductive thin films 41 and 42 and the movable electrode and the conductive thin film 40 and the fixed electrode make ohmic contact, the structure also becomes a path for an electric signal and the resistance is lowered, so that a measurement with higher response can be performed.

In the method for manufacturing an acceleration sensor,
When a method of forming a film for each atomic layer is used in the process of forming the conductive thin films 40, 41, and 42, the conductive thin film can be formed uniformly. Further, in the method for manufacturing an acceleration sensor, after the step of forming a conductive thin film or a subsequent step,
By adding a heat treatment step to make ohmic contact between the conductive thin film and the movable electrode / fixed electrode, it is possible to make ohmic contact between the conductive thin film and the movable electrode / fixed electrode, and reduce the overall resistance. It can also support measurement methods that use high frequencies. (Third Embodiment) Next, a third embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

In this embodiment, as shown in FIGS. 1 and 2, an electrode (wiring) 60 is formed on the square frame 5 of the silicon substrate 1, and the support (base plate 3 + square frame) is formed through the electrode 60. The potential of the section 5) can be controlled or kept constant. Therefore, the support portion (base plate portion 3 + square frame portion 5) can be fixed at a desired potential, noise and the like caused by the potential of the support portion (base plate portion 3 + square frame portion 5) can be reduced, and more accurate High sensing becomes possible. Even in this case, even if the control of the film thickness of the structure is insufficient, it is possible to reduce the variation in the sensitivity of the sensor due to the variation in the capacitance between the movable electrode and the fixed electrode.

The formation of the electrode (wiring) 60 for extracting the potential of the support portion (base plate portion 3 + square frame portion 5) is performed as follows.
When forming the wiring 50 in FIG. 7 or the wiring 2 in FIG.
It may be performed in either of the steps for forming the layers 9 and 30.

[Brief description of the drawings]

FIG. 1 is a plan view showing a semiconductor acceleration sensor according to an embodiment.

FIG. 2 is a perspective view of a semiconductor acceleration sensor.

FIG. 3 is a longitudinal sectional view taken along line AA of FIG. 1;

FIG. 4 is a longitudinal sectional view taken along line BB of FIG. 1;

FIG. 5 is a perspective view of a semiconductor acceleration sensor.

FIG. 6 is a cross-sectional view for explaining a manufacturing process.

FIG. 7 is a cross-sectional view for explaining a manufacturing process.

FIG. 8 is a cross-sectional view for explaining a manufacturing process.

FIG. 9 is a cross-sectional view for explaining a manufacturing process.

FIG. 10 is a sectional view for explaining a manufacturing process.

FIG. 11 is a plan view of a semiconductor acceleration sensor for explaining a conventional technique.

FIG. 12 is a longitudinal sectional view taken along line XX of FIG. 11;

FIG. 13 is a cross-sectional view for explaining a manufacturing process.

FIG. 14 is a cross-sectional view for explaining a manufacturing process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Cavity, 3 ... Base plate part,
4a to 4d: groove, 5: square frame portion, 6: beam structure, 12a
-12d: movable electrode, 13a-13d: movable electrode, 14
a-14b: groove, 15a-15b: insulating material, 16a-
16d: fixed electrode, 17a to 17d: fixed electrode, 18a
~ 18d ... groove, 19a ~ 19d ... insulating material, 20a ~ 2
0d: groove, 21a to 21d: insulating material, 22a to 22d
... fixed electrodes, 23a to 23d ... fixed electrodes, 24a to 24
d: groove, 25a to 25d: insulating material, 26a to 26d:
Grooves, 27a to 27d: insulating material, 40, 41, 42: dielectric thin film.

Continued on the front page (72) Inventor Hiroyuki Wado 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 4M112 AA02 BA07 CA24 CA26 CA36 DA03 EA03 EA07

Claims (27)

[Claims] 1. A support section defined by at least a laterally extending cavity formed in a semiconductor substrate, and a support section defined by the longitudinally extending groove formed in the cavity and the semiconductor substrate, the supporting section being positioned above the cavity, A beam structure having a movable electrode that extends from a portion and is displaced by a mechanical quantity, and is defined by the cavity and the groove, and is located on the cavity;
A fixed electrode extending from the support portion and arranged to face the movable electrode of the beam structure; and a fixed electrode formed between the movable electrode and the support portion and between the fixed electrode and the support portion. A semiconductor dynamic quantity sensor having a groove in which an electrically insulating material is embedded, wherein a dielectric film which also functions as a protective film at the time of substrate etching for forming the cavity is formed on the side walls of the movable electrode and the fixed electrode. A semiconductor dynamic quantity sensor, wherein a body thin film is formed, and the thin film contains at least one of silicon nitride, aluminum oxide, calcium fluoride, zirconium oxide, tantalum oxide, and cerium oxide as a dielectric material. 2. The semiconductor physical quantity sensor according to claim 1, wherein the dielectric thin film has zero residual stress. 3. The semiconductor physical quantity sensor according to claim 1, wherein the dielectric thin film extends in a direction not approaching an opposing electrode. 4. The semiconductor physical quantity sensor according to claim 1, wherein the dielectric thin film is made of silicon, oxygen, and nitrogen. 5. The semiconductor physical quantity sensor according to claim 1, wherein the dielectric thin film is formed of a material having a compressive stress and a material having a tensile stress. 6. The semiconductor physical quantity sensor according to claim 5, wherein the dielectric thin film is a silicon oxide film and a silicon nitride film. 7. The device according to claim 1, wherein the dielectric thin film has a thermal expansion coefficient equivalent to that of the movable electrode / fixed electrode.
7. The semiconductor physical quantity sensor according to any one of items 6 to 6. 8. The semiconductor dynamic quantity sensor according to claim 1, wherein the thickness of the dielectric thin film is 100 nm or more. 9. The semiconductor physical quantity sensor according to claim 1, wherein the semiconductor substrate is a silicon substrate. 10. A method of manufacturing a semiconductor dynamic quantity sensor comprising a support, a beam structure having a movable electrode displaced by a dynamic quantity, and a fixed electrode disposed opposite to the movable electrode of the beam structure. A first step of performing anisotropic etching from the upper surface of the semiconductor substrate to form at least a vertically extending groove for partitioning the beam structure and the fixed electrode; A second step of forming a dielectric thin film by film formation for each atomic layer; and performing a isotropic etching on the semiconductor substrate from a bottom surface of the groove using the dielectric thin film as a protective film to form a cavity extending in a lateral direction. And forming a support part, a beam structure, and a fixed electrode. 3. A method of manufacturing a semiconductor dynamic quantity sensor, comprising: 11. The method according to claim 10, wherein an atomic layer epitaxy method is used in the second step of forming the dielectric thin film. 12. A support section defined by at least a laterally extending cavity formed in the semiconductor substrate, and a support section defined by the longitudinally extending groove formed in the cavity and the semiconductor substrate and located above the cavity. A beam structure having a movable electrode that extends from a portion and is displaced by a mechanical quantity, and is defined by the cavity and the groove, and is located on the cavity;
A fixed electrode extending from the support portion and arranged to face the movable electrode of the beam structure; and a fixed electrode formed between the movable electrode and the support portion and between the fixed electrode and the support portion. A semiconductor dynamic quantity sensor having a groove in which an electrically insulating material is embedded, wherein a conductive film that also functions as a protective film at the time of substrate etching for forming the cavity is formed on the side wall of the movable electrode and the fixed electrode A semiconductor dynamic quantity sensor characterized by forming a conductive thin film. 13. The semiconductor physical quantity sensor according to claim 12, wherein the conductive thin film is a metal. 14. The semiconductor physical quantity sensor according to claim 12, wherein the conductive thin film is a material containing a metal. 15. The semiconductor physical quantity sensor according to claim 14, wherein the conductive thin film is a metal oxide. 16. The conductive thin film extends in a direction that does not approach an opposing electrode.
16. The semiconductor physical quantity sensor according to any one of items 15 to 15. 17. The semiconductor physical quantity sensor according to claim 14, wherein the conductive thin film is formed of metal and silicon. 18. The semiconductor physical quantity sensor according to claim 12, wherein the conductive thin film has no residual stress. 19. The semiconductor dynamic quantity sensor according to claim 12, wherein the conductive thin film is formed of a material having a compressive stress and a material having a tensile stress. 20. The semiconductor dynamic quantity sensor according to claim 12, wherein the conductive thin film has a thermal expansion coefficient equivalent to that of a movable electrode / fixed electrode. 21. The semiconductor physical quantity sensor according to claim 12, wherein the conductive thin film has a thickness of 100 nm or more. 22. The semiconductor physical quantity sensor according to claim 12, wherein the semiconductor substrate is a silicon substrate. 23. The conductive thin film and a movable electrode, and
The semiconductor physical quantity sensor according to any one of claims 12 to 22, wherein the conductive thin film and the fixed electrode are in ohmic contact. 24. A method for manufacturing a semiconductor dynamic quantity sensor comprising a support, a beam structure having a movable electrode displaced by a dynamic quantity, and a fixed electrode disposed opposite to the movable electrode of the beam structure. A first step of performing anisotropic etching from the upper surface of the semiconductor substrate to form at least a vertically extending groove for partitioning the beam structure and the fixed electrode; A second step of forming a conductive thin film by film formation for each atomic layer; and performing a isotropic etching on the semiconductor substrate from a bottom surface of the groove using the conductive thin film as a protective film to form a cavity extending in a lateral direction. And forming a support part, a beam structure, and a fixed electrode. 3. A method for manufacturing a semiconductor physical quantity sensor, comprising: 25. The method according to claim 24, wherein an atomic layer epitaxy method is used in the second step of forming the conductive thin film. 26. A heat treatment step for making ohmic contact between the conductive thin film and the movable electrode / fixed electrode after the second step or the third step of forming the conductive thin film. The method of manufacturing a semiconductor dynamic quantity sensor according to claim 24 or 25. 27. A support section defined by at least a laterally extending cavity formed in a semiconductor substrate, and a support section defined by the cavity and a vertically extending groove formed in the semiconductor substrate, the supporting section being positioned above the cavity, A beam structure having a movable electrode extending from a portion and displaced by a mechanical quantity, defined by the cavity and the groove, located on the cavity,
A fixed electrode extending from the support portion and arranged to face the movable electrode of the beam structure; and a fixed electrode formed between the movable electrode and the support portion and between the fixed electrode and the support portion. A groove in which an electrically insulating material is embedded, wherein the semiconductor physical quantity sensor includes: an electrode for controlling or maintaining a constant potential of the supporting portion on the semiconductor substrate. Semiconductor dynamic quantity sensor.