JPH08335705A - Manufacture of semiconductor mechanical quantity sensor - Google Patents

Abstract

PURPOSE: To prevent a movable section from adhering to a substrate or being damaged when the movable section of a beam structure is formed by etching a sacrifice layer. CONSTITUTION: On the surface of a silicon substrate 1, a silicon oxide film 20 is formed. Part of the oxide film 20 where projections are to be formed is removed to form openings. Then, a silicon oxide film 24 is prepared on the oxide film 20 and then a polysilicon thin film 26 is prepared on the oxide film 24. Part of the thin film 26 where the projections are to be formed is removed to form openings 17 and then the silicon oxide film 20 and 24 are removed by wet etching. The area of each projection reduces by the area of the opening 17. A liquid which substitutes for an etchant enters between the movable section and the substrate 1 and thereby the adhesion of the movable section to the substrate 1 is lowered when drying by the existence of liquid drops between the projections and the substrate 1.

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-structured movable part made of a thin film,
The present invention relates to a method for manufacturing a semiconductor mechanical quantity sensor for detecting mechanical quantities such as acceleration, yaw rate, and vibration.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for miniaturization and cost reduction of semiconductor acceleration sensors. Therefore, the special table 4-5
JP 04003 discloses a differential capacitance type semiconductor acceleration sensor using polysilicon as electrodes. This type of sensor will be described with reference to FIGS. FIG. 14 shows the plane of the sensor, and FIG. 15 shows the DD cross section of FIG.

A movable portion 51 having a beam structure is arranged above the silicon substrate 50 at a predetermined interval. The movable part 51 made of a polysilicon thin film includes beam parts 52, 53, 54,
55, a weight portion 56, and a movable electrode portion 57. The movable part 51 is fixed to the upper surface of the silicon substrate 50 by anchor parts 58, 59, 60, 61. That is, from the anchor portions 58, 59, 60, 61 to the beam portions 52, 53, 54,
55 is extended, and a weight portion 56 is supported by the beam portions 52, 53, 54, 55. A movable electrode portion 57 is provided on the weight portion 56 so as to project therefrom. On the other hand, on the silicon substrate 50, two fixed electrodes 62 are arranged so as to face one movable electrode portion 57. And the silicon substrate 5
When acceleration is applied in the direction parallel to the surface of 0 (shown by G in FIG. 14), the capacitance between the movable electrode portion 57 and the fixed electrode 62 increases on one side and decreases on the other side. It has a structure.

In the manufacture of this sensor, as shown in FIG. 16, a sacrifice layer 63 such as a silicon oxide film is formed on a silicon substrate 50, and an opening 64 is formed at a portion of the sacrifice layer 63 which will be an anchor portion. . After that, as shown in FIG. 17, a polysilicon thin film 65 to be a movable portion is deposited on the sacrificial layer 63 to form a desired pattern. Then, the sacrificial layer 63 under the polysilicon thin film 65 excluding the anchor portion is removed with an etching solution, and the movable portions 51 are arranged above the substrate 50 at predetermined intervals, as shown in FIG.

The step of removing the sacrificial layer by the wet etching will be described in more detail. As shown in FIG. 19, after the silicon substrate 50 is dipped in the etching solution 66 to etch the sacrificial layer 63, the process shown in FIG. As shown, the silicon substrate 50 is immersed in pure water 67 to replace the etching liquid 66 on the surface of the silicon substrate 50 with the pure water 67. Further, the silicon substrate 50 is taken out of the pure water 67 and dried. As a result, it becomes as shown in FIG.

However, when the pure water is dried, as shown in FIG.
As shown in FIG. 1, pure water 68 remains between the silicon substrate 50 and the movable portion 51, and the surface tension of the pure water 68 pulls the movable portion 51 onto the surface of the silicon substrate 50. As a result, as shown in FIG. 22, the movable portion 51 is fixed to the surface of the silicon substrate 50, or the movable portion 51 is damaged (broken).

Therefore, in order to prevent the movable portion 51 (beam) from being fixed or damaged on the surface of the substrate, a projection 69 is provided on the lower surface of the movable portion 51 as shown in FIG. Only the tip surfaces of the projections 69 are attached to reduce the adhesion area of the droplet W formed between the movable portion 51 and the substrate 50 to reduce the adhesion force (the substrate 5 of the movable portion 51 due to surface tension).
It is conceivable to reduce the pulling force to 0).

[0008]

However, the mere provision of the projections 69 cannot sufficiently reduce the adhesive force of the droplets, and the movable portion 51 is fixed to the substrate 50 or the beam is damaged. May occur.

Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor mechanical quantity sensor which can prevent the movable portion from being fixed to the substrate or damaged when the movable portion having a beam structure is formed by etching the sacrificial layer. Especially.

[0010]

According to a first aspect of the present invention, there is provided a beam structure comprising a semiconductor substrate and a thin film which is disposed above the semiconductor substrate with a predetermined space therebetween and which is displaced by the action of a mechanical amount. A method for manufacturing a semiconductor dynamical amount sensor, comprising: a first step of forming a sacrificial layer having recesses for forming protrusions on a surface of a semiconductor substrate; and forming a movable section on the sacrificial layer. Second step of forming an opening by removing a part of the projection forming region in the movable part forming thin film, and wet etching the sacrificial layer under the movable part forming thin film. The gist is a method of manufacturing a semiconductor dynamical amount sensor including a third step of removing the semiconductor dynamic amount sensor.

According to a second aspect of the present invention, in the first step of the first aspect of the invention, the first sacrificial layer is formed on the surface of the semiconductor substrate and the first sacrificial layer is formed in the protrusion formation region. A method of manufacturing a semiconductor dynamical amount sensor, comprising: a step of removing a second sacrificial layer to form an opening, and a step of forming a second sacrificial layer on the first sacrificial layer including the opening. And

[0012]

According to the first aspect of the present invention, the sacrificial layer having the concave portions for forming the projections is formed on the surface of the semiconductor substrate by the first step, and the movable portion is formed on the sacrificial layer by the second step. While forming the forming thin film, a part of the protrusion forming region in the movable part forming thin film is removed to form the opening. By the third step, the sacrificial layer under the movable part forming thin film is removed by wet etching, and the movable part having a beam structure having a projection on the lower surface is formed. At this time, the occupied area (area at the lower end surface) of the protrusion is reduced by the area of the opening.

In the third step, a liquid (pure water or the like) that replaces the etching liquid enters between the movable portion and the substrate, and the area between the movable portion and the substrate is equal to the area of the opening during drying. Since the adhesive force of the droplet between the protrusion and the substrate is weakened, it is possible to prevent the movable part from being pulled by the surface of the substrate to be fixed or damaged.

According to the invention of claim 2, claim 1
In addition to the function of the invention described in (1), in the first step, the first sacrificial layer is formed on the surface of the semiconductor substrate, and the first sacrificial layer in the protrusion formation region is removed to form an opening, A second sacrificial layer is formed on the first sacrificial layer including the opening. The height of the protrusion is determined by the film thickness of the first sacrificial layer in the first step, and the height of the protrusion can be made constant.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a plan view of the semiconductor acceleration sensor of this embodiment. 2 shows a cross section taken along the line AA of FIG. 1, FIG. 3 shows a cross section taken along the line BB of FIG. 1, and FIG. 4 shows a cross section taken along the line CC of FIG.

A silicon oxide film 2 as a gate insulating film is formed on a part of the P-type silicon substrate 1.
This silicon oxide film 2 is for reducing the leak current on the surface of the substrate and for suppressing the change in transistor characteristics over time. Similarly, a silicon oxide film 3 (preferably a LOCOS oxide film) having a predetermined thickness is formed on a part of the P-type silicon substrate 1. The silicon oxide film 3 is for insulating isolation. Further, the insulating film 4 is formed on the silicon oxide film 2 and the silicon oxide film 3.
(Preferably a silicon nitride film, hereinafter the insulating film 4 is referred to as a silicon nitride film) is formed, and the silicon nitride film 4 protects the silicon oxide film 2 when a sacrifice layer described later is etched. In this embodiment, the P-type silicon substrate 1, the silicon oxide film 2, the silicon oxide film 3 and the silicon nitride film 4 constitute a semiconductor substrate.

A movable part 5 made of a polysilicon thin film is provided above the silicon oxide film 4 in the formation region of the silicon oxide film 3 in the formation region of the silicon oxide film 2. The movable portion 5 includes four beam portions 7, a weight portion 8 and movable gate electrode portions 9 and 10 as gate electrode portions.
The movable portion 5 is fixed by four anchor portions 6 and is arranged above the silicon substrate 1 (silicon nitride film 4) with a predetermined space. The anchor portion 6 is made of a polysilicon thin film like the movable portion 5 and is integrated with the movable portion 5. More specifically, four anchor portions 6 are disposed on the silicon nitride film 4, and the anchor portions 6 are strip-shaped four.
The beam portion 7 of the book extends and the square weight portion 8 is supported. The weight portion 8 has rectangular movable gate electrode portions 9 and 10
Are projected in opposite directions. That is, the movable gate electrode portions 9 and 10 are supported by the doubly supported beam portions (the beam portions 7) and can be displaced in the direction perpendicular to the surface of the silicon substrate 1 and the direction parallel thereto.

As shown in FIG. 4, the silicon substrate 1 below the movable gate electrode portion 9 of the movable portion 5 has a source / drain portion formed of N-type impurity diffusion layers on both sides of the movable gate electrode portion 9. Fixed electrodes 11 and 12 are formed. Similarly, as shown in FIG. 1, the silicon substrate 1 below the movable gate electrode portion 10 of the movable portion 5 has a source / drain portion formed of N-type impurity diffusion layers on both sides of the movable gate electrode portion 10. Fixed electrodes 13 and 14 are formed. As shown in FIG. 4, a channel region 15 is formed between the fixed electrodes 11 and 12 on the silicon substrate 1, and the channel region 15 is formed by applying a voltage between the silicon substrate 1 and the movable gate electrode portion 9. It happened. Then, by applying a voltage between the fixed electrodes 11 and 12, a drain current flows in the channel region 15. Similarly, the fixed electrode 1 on the silicon substrate 1
A channel region (not shown) is formed between 3 and 14, and the channel region includes the silicon substrate 1 and the movable gate electrode portion 10.
It is caused by applying a voltage between the and.
Then, by applying a voltage between the fixed electrodes 13 and 14, a drain current flows in this channel region.

As shown in FIGS. 1 and 3, a large number of protrusions 16 are formed on the lower surface of the weight portion 8 of the movable portion 5. Specifically, in FIG. 1, five on the left side and five on the right side are arranged in parallel, for a total of ten. This protrusion 16
Has a rectangular shape, and its height is H1 as shown in FIG.
Has become. Further, as shown in FIG. 3, the air gap (gap) L1 between the tip of the protrusion 16 and the silicon substrate 1 (more specifically, the silicon nitride film 4) is, as shown in FIG. 4, the movable gate electrode portions 9 and 10. And the air gap between the silicon substrate 1 (more specifically, the silicon nitride film 4)
It is smaller than L2.

A square opening 17 is formed at the center of each protrusion 16 so as to vertically penetrate therethrough. This opening 17
The area of the tip surface (lower surface) of the protrusion 16 is
Is smaller by the area of.

Further, the weight portion 8 of the movable portion 5 is provided with a large number of openings 18 penetrating up and down, and the opening 18 and the above-mentioned openings 17 allow an etching solution to penetrate at the time of sacrifice layer etching described later. It's easier to do.

On the surface of the silicon substrate 1, a movable part 5
The lower electrode 1 made of an N-type impurity diffusion layer in a region where the fixed electrodes 11, 12, 13, and 14 are not present in the portion facing the
9 is formed. This lower electrode 19 is kept at the same potential as that of the movable part 5, and the silicon substrate 1 and the movable part 5 are kept at the same potential.
The electrostatic force generated between and is suppressed.

Peripheral circuits (not shown) are formed around the area where the movable portion 5 is arranged on the silicon substrate 1. Then, the peripheral circuit and the movable part 5, the peripheral circuit and the fixed electrode 11,
The peripheral circuits 12, 13, 14 and the lower electrode 19 are electrically connected.

Next, the operation of this semiconductor acceleration sensor will be described. When a voltage is applied between the movable portion 5 and the silicon substrate 1 and between the fixed electrodes 11, 12 (13, 14), the channel region 15 is formed and the fixed electrodes 11, 12 (1
Current flows between 3 and 14). Here, the semiconductor acceleration sensor receives the acceleration, and the X ₊ direction (the substrate 1
When the movable gate electrode portions 9 and 10 (movable portion 5) are displaced in the direction parallel to the surface of the fixed electrode, the area of the channel region between the fixed electrodes (channel width referred to as a transistor) changes, and thus the fixed electrode 11 , 12 current decreases,
The current flowing through the fixed electrodes 13 and 14 increases. Moreover, FIG.
When the movable gate electrode portions 9 and 10 (movable portion 5) are displaced in the X _- direction (direction parallel to the surface of the substrate 1) indicated by,
By changing the area of the channel region between the fixed electrodes (channel width in the transistor), the fixed electrodes 11 and 12 are changed.
The current flowing through the fixed electrodes 13 and 14 increases and the current flowing through the fixed electrodes 13 and 14 decreases.

On the other hand, when the semiconductor acceleration sensor receives acceleration, the Z direction (direction perpendicular to the surface of the substrate 1) shown in FIG.
When the movable gate electrode portions 9 and 10 are displaced, the carrier concentration in the channel region 15 is reduced due to the change in the electric field strength, so that the current is simultaneously reduced.

As described above, the semiconductor acceleration sensor according to the present invention has the movable gate electrode portions 9 and 10 and the fixed electrodes 11 and 1 caused by acceleration.
The current flowing between the fixed electrodes 11 and 12 and between the fixed electrodes 13 and 14 changes due to the change in the relative position with respect to 2 and 13 and 14, and the two-dimensional acceleration is detected by the magnitude and phase of this current change. be able to.

In the normal acceleration range, the sensor normally operates as an acceleration sensor, but when an excessive acceleration is applied in the vertical direction of the silicon substrate 1, the movable portion 5 is deformed in the vertical direction by the acceleration. I'll try, but the protrusion 16
Therefore, the excessive deformation is suppressed. That is, the protrusion 16 functions as a movable range limiting section. As a result, before the movable gate electrode portions 9 and 10 come into contact with the silicon nitride film 4, the projection 16 comes into contact with the silicon nitride film 4 and the deterioration of the transistor characteristics of the MISFET is avoided.

Next, the steps of manufacturing the acceleration sensor will be described with reference to FIGS.
This will be described with reference to FIG. 5 to 12 are BB of FIG.
It shows a state in a cross section. As shown in FIG. 5, first, a P-type silicon substrate 1 is prepared, and a silicon oxide film 3 (preferably a LOCOS oxide film) is formed on a predetermined region of the surface thereof. Further, a silicon oxide film 2 as a gate insulating film is formed on the P-type silicon substrate 1 in a region other than the region where the silicon oxide film 3 is formed by a thermal oxidation method. Further, impurities are introduced into the P-type silicon substrate 1 by ion implantation and heat treatment is performed to lower the lower electrode 1 made of an N-type impurity diffusion layer.
9 and the source / drain regions (fixed electrodes 11 to 14) of the MISFET (not shown) are formed at the same time. further,
A silicon nitride film 4 is formed on the entire surfaces of the silicon oxide film 2 and the silicon oxide film 3 by low pressure CVD or the like.

Subsequently, as shown in FIG. 6, a silicon oxide film 20 as a first sacrificial layer is formed on the silicon nitride film 4.
Are formed on the entire surface by plasma CVD or the like. The thickness of the silicon oxide film 20 is set to t1.

Further, as shown in FIG. 7, a resist 21 is applied on the silicon oxide film 20 and an opening 22 is formed through a photo process. The opening 22 is a portion (projection formation region) where the projection 16 shown in FIG. 3 is formed. The opening 22 is made as small as possible in order to reduce the area occupied by the projection 16 (area at the lower end surface).

Then, as shown in FIG.
The silicon oxide film 20 is etched through the opening 22 to form an opening 23 in the projection formation region. The etching solution used at this time is, for example, an HF solution that provides a sufficient selection ratio between the silicon oxide film 20 and the silicon nitride film 4. When wet etching using an HF solution is performed, the opening 23 of the silicon oxide film becomes larger than the opening 22 of the resist due to overetching.

Next, the resist 21 is removed, and as shown in FIG. 9, a silicon oxide film 24 as a second sacrificial layer is formed by plasma CVD or the like. At this time, a recess (opening) 25 is formed by the opening 23. In this case, due to the effect of the step coverage, the area of the recess 25 where the projection 16 is formed is smaller than the area of the opening 23 increased by the overetching, and the area occupied by the projection 16 is reduced (W1 in FIG. 9). <W2). Also, the depth H of the recess 25
1 is the film thickness t1 of the silicon oxide film 20.

In this way, the sacrificial layers (20, 24) having the recesses 25 for forming protrusions are formed on the surface of the silicon substrate 1. Next, as shown in FIG. 10, a polysilicon thin film 26 as a movable part forming thin film is formed by low pressure CVD or the like. At this time, the shape of the base of the polysilicon thin film 26 is reflected, and the protrusion forming portion 27 is formed in the recess 25.

Next, as shown in FIG. 11, the polysilicon thin film 26 is patterned into the shape of the movable portion, and a part of the projection forming region is removed to form the opening 17. That is, the anchor portion 6, the beam portion 7, the weight portion 8, and the movable gate electrode portions 9 and 10 are simultaneously formed at the same time, and the polysilicon thin film 2 in the formation region of the openings 17 and 18 is formed.
6 is removed. In this way, the opening 17 is provided in the region where the protrusion 16 is formed, a part of the protrusion forming portion 27 is removed, and the occupied area (the area at the lower end surface) is reduced accordingly. A dry method with less over-etching is preferable for the etching for patterning the movable portion and the opening.

Finally, as shown in FIG. 12, the silicon substrate 1 is placed in an HF solution as an etching solution (see FIG.
(Similar to 9), the silicon oxide films 20 and 24 as the sacrifice layer under the movable portion formation region are etched. As a result, the movable portions 5 having a beam structure having the projections 16 on the lower surface are arranged on the silicon nitride film 4 with a predetermined space therebetween.

Further, the silicon substrate 1 is taken out from the HF solution. In this state, since the HF solution is attached to the substrate surface, the silicon substrate 1 is put in pure water (see FIG. 20).
same as). In this way, the sacrificial layer etching solution is replaced with pure water. Further, the silicon substrate 1 is taken out from pure water and dried. In this drying step, pure water enters between the movable portion 5 and the substrate 1, and droplets adhere only between the protrusion 16 of the movable portion 5 and the silicon substrate 1. However, protrusion 1
Since 6 has an opening 17 that penetrates vertically in a partial region, the area of attachment of water droplets formed between the protrusion 16 and the substrate 1 is small. Therefore, the surface tension is weak, and the pulling force of the movable part 5 on the substrate surface is also weak, so that the movable part 5 is weak.
Does not stick to or damage the surface of the board. That is,
Although the movable portion 5 tends to be pulled by the surface of the substrate, the adhesive force becomes smaller due to the decrease in the area where the droplets adhere, and the adhesive force is weaker than the restoring force of the beam, and the movable portion 5 separates from the silicon substrate 1. .

The height H1 of the protrusion 16 is equal to the film thickness t1 of the silicon oxide film 20. That is, the height H1 of the protrusion 16 can be adjusted by adjusting the film thickness of the silicon oxide film 20.

Thus, in this embodiment, the silicon substrate 1
Oxide films 20 and 24 (sacrificial layers) having recesses 25 for forming protrusions are formed on the surface of the substrate (first step), and a polysilicon thin film as a movable part forming thin film is formed on the silicon oxide films 20 and 24. 26, a part of the projection forming region of the polysilicon thin film 26 is removed to form the opening 17 (second step).
The silicon oxide films 20 and 24 under 6 were removed by wet etching (third step). In the movable portion 5, the area occupied by the protrusion 16 (the area at the lower end surface) is reduced by the area of the opening 17. During the etching of the sacrificial layer, a solution (pure water or the like) that replaces the etching solution enters between the movable portion 5 and the substrate 1, and the protrusion 16 is formed between the movable portion 5 and the substrate 1 during drying. Since the adhesive force due to the liquid droplet between the substrate 1 and the substrate 1 is weakened by the area of the opening 17, the movable portion 5 is prevented from being pulled and fixed to the surface of the substrate. That is, even if droplets are attached during etching of the sacrifice layer during the manufacturing process, the attached portion is only the tip portion of the protrusion 16 other than the opening portion 17, and the attached area is greatly reduced, and the adhesive force is increased accordingly. This significantly reduces the damage to the beam, and the movable portion 5 can be separated from the substrate by the restoring force of the beam portion 7.

That is, the area in which the movable portion 5 of the sensor adheres to the substrate 1 is significantly reduced to reduce the adhesive force, and the movable portion 5 can be separated from the substrate 1 by the restoring force of the beam portion. Also, the first
In the step, the silicon oxide film 20 as the first sacrificial layer is formed on the surface of the silicon substrate 1, the silicon oxide film 20 in the protrusion formation region is removed to form the opening 23, and the opening 23 is included. Second on the silicon oxide film 20
A silicon oxide film 24 was formed as a sacrificial layer. Therefore, the height of the protrusion 16 is determined by the film thickness of the silicon oxide film 20, and the height of the protrusion 16 can be made constant.

The present invention is not limited to the above embodiment. For example, in the above embodiment, as shown in FIG. 3, an opening 17 is provided in the center of the protrusion 16; Although the structure is such that the protrusion 16 is provided around the portion 17, the opening 17 may be formed in a region including one side surface of the protrusion 28 as shown in FIG.

Further, ten projections 16 are formed as shown in FIG. 1, but the number may be any suitable number and may be one or more. Further, although the protrusion 16 is shown as a rectangle, it does not have to be a rectangle and may be a circle, a triangle or any other shape. Similarly,
Although the opening 17 is shown as a rectangle, it does not have to be a rectangle,
It may be a circle, triangle, or any other shape.

Further, it may be embodied as a semiconductor mechanical quantity sensor for detecting a mechanical quantity such as yaw rate and vibration in addition to acceleration.

[0043]

As described above in detail, according to the invention described in claim 1, when the movable portion of the beam structure is formed by the sacrifice layer etching, it is possible to prevent the movable portion from being fixed to the substrate or damaged. Exhibits excellent effects that can be achieved.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), the height of the protrusion is determined by the film thickness of the first sacrificial layer, and the height of the protrusion can be stabilized.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view taken along line CC of FIG.

FIG. 5 is a cross-sectional view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 6 is a cross-sectional view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 7 is a sectional view showing a manufacturing process of the semiconductor acceleration sensor.

FIG. 8 is a sectional view showing a manufacturing process of the semiconductor acceleration sensor.

FIG. 9 is a cross-sectional view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 10 is a cross-sectional view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 11 is a cross-sectional view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 12 is a cross-sectional view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 13 is a cross-sectional view corresponding to BB of FIG. 1 of another embodiment.

FIG. 14 is a plan view of a conventional semiconductor acceleration sensor.

15 is a cross-sectional view taken along line DD of FIG.

FIG. 16 is a sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 17 is a cross-sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 18 is a cross-sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 19 is a cross-sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 20 is a cross-sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 21 is a sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 22 is a cross-sectional view showing a manufacturing process of a plan view of a conventional sensor.

FIG. 23 is a sectional view showing a sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate which comprises a semiconductor substrate, 2 ... Silicon oxide film which comprises a semiconductor substrate, 3 ... Silicon oxide film which comprises a semiconductor substrate, 4 ... Silicon nitride film which comprises a semiconductor substrate, 5 ... Movable part, 16 ... Protrusion, 17 ... Opening, 20
... Silicon oxide film as first sacrificial layer, 24 ... Silicon oxide film as second sacrificial layer, 25 ... Recess, 26 ... Polysilicon thin film as thin film for forming movable part

Claims (2)

[Claims] 1. A semiconductor substrate, and a semiconductor substrate disposed above the semiconductor substrate with a predetermined space therebetween.
A method for manufacturing a semiconductor dynamic quantity sensor, comprising: a movable part having a beam structure made of a thin film, which is displaced by the action of a mechanical quantity, wherein a sacrificial layer having a recess for forming a projection is formed on a surface of a semiconductor substrate. 1 step, and a second step of forming a thin film for forming a movable portion on the sacrificial layer, and removing a part of a region for forming a protrusion in the thin film for forming a movable portion to form an opening, And a third step of removing the sacrificial layer under the movable portion forming thin film by wet etching. 2. The first step comprises: forming a first sacrificial layer on a surface of a semiconductor substrate and removing the first sacrificial layer in a protrusion formation region to form an opening; and the opening. And a step of forming a second sacrificial layer on the first sacrificial layer including the above.