JPH08111534A - Semiconductor dynamic quantity sensor and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a semiconductor dynamic quantity sensor having a movable range limiting member in which steps are less likely to be generated, and manufacture thereof. CONSTITUTION: A beam structure body is provided on a silicon substrate 1, and a movable electrode portion constituting a part of the beam structure body is located above the silicon substrate 1 at a predetermined distance. The movable electrode portion is displaced by acceleration. A fixed electrode is formed on the silicon substrate 1. The fixed electrode is formed by forming an impurity diffusion layer on the silicon substrate 1. A current flowing through the fixed electrode is changed by a change in the position thereof relative to the movable electrode portion due to acceleration. A bridge 23 is provided on a beam portion 8 constituting a part of the beam structure body. The bridge 23 is extended from the silicon substrate 1 to surround the beam portion, thus limiting a movable range of the movable electrode portion. Films 24, 25 of the bridge 23 are formed on the surface of the silicon substrate 1 on both lateral sides of the beam portion 8, and have a predetermined thickness t3. A film 26 suspends the films 24, 25.

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, and more particularly to a semiconductor dynamic quantity sensor for detecting a mechanical quantity such as acceleration, yaw rate, vibration, etc. The present invention relates to a semiconductor mechanical quantity sensor used in a bag system or the like.

[0002]

2. Description of the Related Art A semiconductor acceleration sensor having a beam structure is
For example, it is shown in SAE-910496. This sensor has the structure shown in FIG. That is, the beam 43 is extended from the anchor portion 42 on the silicon substrate 41, and the mass portion 44 is supported by the beam 43. A movable electrode 45 is formed on a part of the mass portion 44. or,
The fixed electrode 46 is arranged on the silicon substrate 41 so as to face the movable electrode 45. Then, when acceleration is applied in a direction parallel to the surface of the silicon substrate 41 (indicated by G in FIG. 15), the movable electrode 45 is displaced, and the capacitance between the movable electrode 45 and the fixed electrode 46 due to the displacement. The acceleration is detected by the change of.

However, such a semiconductor acceleration sensor has a problem that the beam is damaged by an excessive acceleration generated by a water flow or a drop during dicing in the manufacturing process. In order to solve this, the present applicant has proposed a semiconductor acceleration sensor having a movable range limiting function in Japanese Patent Application No. 6-44354. This is shown in FIG.
7, 18, 19, 20 are shown. 16 is a plan view of the sensor, and FIG. 17 shows a cross section taken along the line EE of FIG.
8 shows the FF cross section of FIG. 16, and FIG. 19 shows G-F of FIG.
FIG. 20 shows a G cross section, and FIG. 20 shows a HH cross section of FIG. The sensor is a MISFET type acceleration sensor, and a beam structure 48 is provided on a semiconductor substrate 47, and a gate electrode part 49 is provided in a part thereof. Further, the source / drain section 50 is formed on the semiconductor substrate 47, and the current flowing between the source / drain changes due to the change in the relative position with the gate electrode section 49 due to the acceleration. Further, as shown in FIG. 20, a movable range limiting member 51 having a bridge structure is provided around the displaceable beam 48a to limit the movable range of the beam 48a. Furthermore, the movable range limiting member 51 is formed by simultaneously forming a film with the same material when forming the wiring, thereby suppressing an increase in the number of processes for providing the movable range limiting member 51.

[0004]

However, as a result of a detailed study, it was found that when the movable range limiting member 51 is formed by one-time film formation, step breakage is likely to occur due to poor step coverage. It was That is, as indicated by H1 in FIG. 20, it was found that a large step is generated in the movable range limiting member 51 and a step break easily occurs, which makes it difficult to construct a bridge structure.

Therefore, an object of the present invention is to provide a semiconductor dynamic quantity sensor provided with a movable range limiting member that is unlikely to cause step breaks, and a method for manufacturing the same.

[0006]

According to a first aspect of the present invention, a beam structure is provided on a semiconductor substrate, and displacement of a gate electrode portion forming a part of the beam structure due to the action of a mechanical quantity is caused. A semiconductor dynamic quantity sensor for detecting by a current flowing through a source / drain portion formed of an impurity diffusion layer formed on the semiconductor substrate, wherein the semiconductor substrate surrounds a movable portion of the beam structure. And a movable range limiting member that limits the movable range of the gate electrode portion, is formed on the surface of the semiconductor substrate on both sides of the movable portion of the beam structure, and has a predetermined film thickness. A gist of the present invention is a semiconductor dynamical amount sensor including a second film that bridges the first film.

According to a second aspect of the present invention, the first film in the first aspect of the invention is a laminate of two films, and at least one of the two films is a beam structure. The gist of the invention is a semiconductor dynamical quantity sensor made of the same material as the member constituting the.

A third aspect of the present invention has as its gist a semiconductor dynamic quantity sensor in which the second film in the first or second aspect of the invention is made of a wiring material or a passivation film.

According to a fourth aspect of the present invention, a beam structure is provided on a semiconductor substrate, and a movable range control member extending from the semiconductor substrate and surrounding a movable portion of the beam structure is provided. The displacement of the gate electrode portion forming a part of the beam structure due to the action of the mechanical amount is detected by the current flowing in the source / drain portion formed of the impurity diffusion layer formed on the semiconductor substrate, and the movable range is limited. A method of manufacturing a semiconductor dynamical quantity sensor, wherein a movable range of the gate electrode section is limited by a member, wherein a predetermined area is provided on both sides of a predetermined area that is a movable area of the beam structure on the main surface of the semiconductor substrate. After forming the first film having a film thickness,
A sacrificial layer is formed around a predetermined portion that is a movable part of the beam structure, a second film is subsequently formed so as to bridge the first film, and the sacrificial layer is removed by etching to form a first film. The gist is a method of manufacturing a semiconductor dynamical amount sensor in which a movable range limiting member including a first film and a second film bridging the first film is formed.

According to a fifth aspect of the invention, in the invention according to the fourth aspect, the second film is made of a wiring material or a passivation film, and this film is formed in a wiring process or a passivation film forming process. The gist is a method of manufacturing a certain semiconductor dynamic quantity sensor.

According to a sixth aspect of the present invention, a beam structure is provided on a semiconductor substrate, and a movable range control member extending from the semiconductor substrate and surrounding a movable portion of the beam structure is provided. The displacement of the gate electrode portion forming a part of the beam structure due to the action of the mechanical amount is detected by the current flowing in the source / drain portion formed of the impurity diffusion layer formed on the semiconductor substrate, and the movable range is limited. A method of manufacturing a semiconductor dynamic quantity sensor, wherein a movable range of the gate electrode part is limited by a member, the first step of forming a first film having a predetermined film thickness on a main surface of the semiconductor substrate, A second step of forming a second film having a predetermined film thickness on both sides of a formation region of the beam structure on the first film and a predetermined portion which is a movable part of the beam structure, and the beam structure The movable part of Third forming the third film around locations
A fourth step of forming a fourth film on the third film so as to bridge the second film, and the first film and the beam structure below a formation region of the beam structure excluding an anchor portion The third film around a predetermined portion which is a movable part of the body is removed by etching to form a beam structure and the second film and the second film.
The gist is a method of manufacturing a semiconductor dynamical amount sensor including a fifth step of forming a movable range limiting member including a first film and a fourth film below a film.

According to a seventh aspect of the present invention, in the sixth aspect of the invention, the fourth film in the fourth step is made of a wiring material or a passivation film, and the fourth step is a wiring step or a passivation film forming step. The gist of the method is a semiconductor dynamic quantity sensor manufacturing method that is performed at the same time.

[0013]

According to the first aspect of the present invention, the movable range limiting member functions as a stopper to limit the movable range of the gate electrode portion and avoid damage to the beam. Here, the movable range control member includes a first film disposed on both sides of the movable portion of the beam structure, and a second film that bridges the first film. Therefore, in comparison with the step in the case where the movable structure of the beam structure is formed only by surrounding the movable portion of the beam structure without providing the first film, in this configuration, the second film is formed by the thickness of the first film. The step difference of the second film becomes small, and the step breakage of the second film hardly occurs.

That is, for example, as shown in FIG. 5, when the first films 24 and 25 are provided on the semiconductor substrate 1 and the second film 26 is provided thereon, the first films 24 and 25 are formed. Assuming that the second film 26 is not provided, the step difference is H1 (the same as H1 shown in FIG. 20), whereas the first film 2 is
By providing Nos. 4 and 25, the step difference of the second film 26 is reduced by the film thickness t3 of the first films 24 and 25, and H2
(= H1-t3). As a result, breakage of the second film 26 is unlikely to occur.

According to the invention described in claim 2, claim 1
In addition to the function of the invention described in (1), the first film is composed of a laminate of two films, and at least one of the two films is composed of the same material as a member forming the beam structure, It is easier to manufacture as compared with the case where both the two films use the films of the exclusive different materials. That is, compared to the case where both of the two films use dedicated films, only one film is made of the same material as the member forming the beam structure, or both are made of the same material as the member forming the beam structure. In the case of, the manufacturing becomes easy.

According to the invention of claim 3, claim 1
Alternatively, in addition to the function of the invention described in item 2, the second film is made of a wiring material or a passivation film, and the manufacture is easy without using a dedicated film for forming the second film.

According to the fourth aspect of the present invention, the first film having a predetermined film thickness is formed on both sides of the predetermined portion which is the movable portion of the beam structure on the main surface of the semiconductor substrate. Then, a sacrificial layer is formed around a predetermined portion that is a movable portion of the beam structure, and a second film is formed so as to bridge the first film. Further, the sacrificial layer is etched away and the first
The movable range limiting member is formed of the first film and the second film that bridges the first film.

As a result, the semiconductor dynamical quantity sensor according to claim 1 is manufactured. According to the invention of claim 5,
In addition to the effect of the invention described in claim 4, the second film is made of a wiring material or a passivation film, and this film is formed simultaneously with the wiring process or the passivation film forming process. As a result, the semiconductor dynamic quantity sensor according to claim 3 is manufactured.

According to the invention described in claim 6, the first film having a predetermined thickness is formed on the main surface of the semiconductor substrate in the first step, and the beam structure on the first film is formed in the second step. A second film having a predetermined film thickness is formed on both sides of the formation region and a predetermined portion serving as a movable portion of the beam structure. And the third
The step forms a third film around a predetermined portion which is a movable part of the beam structure, and the fourth step forms the fourth film so as to bridge the second film on the third film. Further, in the fifth step, the first film under the formation region of the beam structure excluding the anchor portion and the third film around the predetermined portion which is the movable portion of the beam structure are removed by etching, and the beam structure is removed. While being formed, a movable range limiting member including the second film and the first film and the fourth film below the second film is formed. As a result, the semiconductor dynamical quantity sensor according to claim 2 is manufactured.

According to the invention of claim 7, claim 6
In addition to the function of the invention described in (1), the fourth film is made of a wiring material or a passivation film, and the fourth step is performed simultaneously with the wiring step or the passivation film forming step. As a result, the semiconductor dynamic quantity sensor according to claim 3 is manufactured.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a MISFET type semiconductor acceleration sensor will be described below with reference to the drawings.

FIG. 1 is a plan view of the semiconductor acceleration sensor of this embodiment. 2 shows a cross section taken along the line AA of FIG.
FIG. 3 shows a cross section taken along the line BB of FIG. 1, and FIG.
C cross section is shown and FIG. 5 shows the DD cross section of FIG.

A silicon nitride film 2 as a gate insulating film is formed on the entire surface of a P-type silicon substrate 1 as a semiconductor substrate. This silicon nitride film 2 is for reducing the leak current on the surface of the substrate and for suppressing the change in transistor characteristics over time. A beam structure 38 is provided on the silicon substrate (silicon nitride film 2). The beam structure 38 is composed of anchor portions 3 and 4 and a movable portion 5.

More specifically, the silicon nitride film 2
Anchor portions 3 and 4 are disposed on the upper side of the anchor portions 3 and 4, and the anchor portions 3 and 4 are made of a silicon oxide film having a predetermined thickness.
The anchor portions 3 and 4 are strip-shaped and extend linearly and parallel to each other. A movable portion 5 made of a polysilicon thin film is provided on the anchor portions 3 and 4. The movable part 5 includes anchor parts 6, 7, beam parts 8, 9, 10, 11 and a weight part 12 and movable electrode parts 13, 1 as gate electrode parts.
4, the beam portions 8, 9, 10, 11 and the weight portion 12 and the movable electrode portions 13, 14 are arranged above the silicon substrate 1 (silicon nitride film 2) at a predetermined interval.

On the anchor parts 3 and 4, the anchor parts 6 and 7 of the movable part 5 having the same size as the anchor parts 3 and 4 are arranged, and the beam parts 8, 9 and 10 from the anchor parts 6 and 7 to the strip-shaped beam parts. ，
11 extends, and a square weight portion 12 is supported.
On the weight portion 12, rectangular movable electrode portions 13 and 14 are provided so as to project in opposite directions. That is, the movable electrode portion 13,
Reference numeral 14 is a double-supported beam (beam portions 8, 9, 10, 11 and weight portion 1
It is supported by 2) and can be displaced in a direction perpendicular to the surface of the silicon substrate 1 and a direction parallel to the surface.

As shown in FIG. 4, in the silicon substrate 1 below the movable electrode portion 14 of the movable portion 5, the movable electrode portion 14 is provided with source / drain portions composed of N-type impurity diffusion layers on both sides thereof. Fixed electrodes 15 and 16 are formed.
Similarly, as shown in FIG. 1, the movable electrode portion 13 of the movable portion 5 is
Fixed electrodes 17 and 18 as source / drain portions made of N-type impurity diffusion layers are formed on both sides of the movable electrode portion 13 on the silicon substrate 1 below. FIG.
As shown in, the fixed electrode 15 on the silicon substrate 1,
A channel region 19 is formed between 16 and the channel region 19 is generated by applying a voltage between the silicon substrate 1 and the movable pole portion 14. Then, by applying a voltage between the fixed electrodes 15 and 16, a drain current flows in the channel region 19. Similarly, a channel region (not shown) is formed between the fixed electrodes 17 and 18 on the silicon substrate 1, and the channel region is generated by applying a voltage between the silicon substrate 1 and the movable electrode portion 13. is there. Then, by applying a voltage to the fixed electrodes 17 and 18, a drain current flows in this channel region.

An interlayer insulating film 20 made of a PSG film is formed on the anchor portion 6 of the movable portion 5, and the interlayer insulating film 2 is formed.
An opening 21 is formed at 0 (see FIGS. 1 and 2).
An aluminum wiring 22 is formed in the opening 21, and the aluminum wiring 22 and the movable portion 5 are electrically contacted with each other. As shown in FIGS. 1 and 3, the aluminum wiring 22 extends on the interlayer insulating film 20 and further extends on the silicon substrate 1.

As shown in FIG. 1, each beam section 8 of the movable section 5,
Bridges 23, which are movable range limiting members, are arranged at positions near the weight portion 12 in 9, 10, and 11, respectively. The bridge 23 has a band shape as a whole. As shown in FIG. 5, each bridge 23 extends from the upper surface of the silicon substrate 1 (silicon nitride film 2) and is arranged so as to surround the beam portions 8, 9, 10, 11 with a predetermined gap. There is. That is, it extends from the substrate 1 so as to surround the movable portion of the beam structure 38, that is, the vicinity of the position of the beam portion 8, 9, 10, 11 near the weight portion 12.

In this way, the bridges 23 are arranged around the beam portions 8, 9, 10, 11 as stoppers at predetermined intervals. That is, they are arranged at a predetermined interval in a direction parallel to the surface of the substrate and a direction perpendicular to the surface. The bridge 23 restricts the movable range of the beam portions 8, 9, 10, and 11.

The bridge 23 will be described in detail. The bridge 23 includes a silicon oxide film 24 which constitutes the first film.
And a polysilicon film 25 forming a first film and an aluminum thin film 26 as a second film. Silicon substrate 1
Beams 8, 9, 1 on the surface of (silicon nitride film 2)
A silicon oxide film 24 having a predetermined film thickness t1 is arranged on both sides of 0 and 11, and a predetermined film thickness t is formed thereon.
A polysilicon film 25 having 2 is formed. Thus, the two films 24 and 25 form a laminated body and serve as an anchor portion of the bridge 23. Furthermore, aluminum thin film 2
6 is arranged so as to bridge the polysilicon film 25. Further, the silicon oxide film 24 on the lower layer side in the laminated body of the two films 24 and 25 is the anchor portion 3, 4 of the beam structure 38.
And the upper polysilicon film 25 is made of the same material as the beam portions 8, 9, 10, 11 of the beam structure 38. Furthermore, the aluminum thin film 26 is the aluminum wiring 2
It is a wiring material similar to 2.

In such a bridge 23, the aluminum thin film 26 does not easily break. In other words, when the films 24 and 25 are not provided, the step difference of the film 26 is H1, whereas when the films 24 and 25 are provided, the step difference of the film 26 is the total film thickness t3 (= 3) of the films 24 and 25. t
It becomes smaller by 1 + t2) and becomes H2 (= H1-t3).

As shown in FIG. 1, on the surface of the silicon substrate 1, N is formed in a region where the fixed electrodes 15, 16, 17, 18 are not provided in the portion of the beam structure 38 facing the movable portion 5.
A lower electrode 27 made of a type impurity diffusion layer is formed. The lower electrode 27 is kept at the same potential as that of the movable portion 5, and suppresses the electrostatic force generated between the silicon substrate 1 and the movable portion 5. Also, the bridge 23
(Polysilicon film 25 and aluminum thin film 26) is the lower electrode 2
7 and the lower electrode 27 and the bridge 23 are equipotential. Therefore, electrostatic attraction is not generated in the beam portions 8, 9, 10, 11.

Peripheral circuits (not shown) are formed around the region where the movable portion 5 is arranged on the silicon substrate 1. The peripheral circuit and the aluminum wiring 22 are connected, the peripheral circuit and the fixed electrodes 15, 16, 17, 18 are electrically connected, and further, the peripheral circuit and the lower electrode 27 are electrically connected. ing.

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 15, 16 (17, 18), the channel region 19 is formed and the fixed electrodes 15, 16 (1
Voltage flows between 7, 18). Here, when the movable electrode portions 13 and 14 (movable portion 5) are displaced in the X ₊ direction (direction parallel to the surface of the substrate 1) shown in FIG. By changing the area of the channel region between them (the channel width in the transistor), the current flowing through the fixed electrodes 15 and 16 decreases and the current flowing through the fixed electrodes 17 and 18 increases. In addition, the movable electrode unit 1 is arranged in the X _- direction (direction parallel to the surface of the substrate 1) shown in FIG.
When 3, 4 (movable part 5) is displaced, the area of the channel region between the fixed electrodes (channel width in the transistor) changes, so that the current flowing through the fixed electrodes 15, 16 increases and the fixed electrode 17 , 18 decreases. On the other hand, when the movable electrode portions 13 and 14 are displaced in the Z direction (direction perpendicular to the surface of the substrate 1) shown in FIG. Since the carrier concentration decreases, the current decreases at the same time.

As described above, the present acceleration sensor has the movable electrode portions 13 and 14 and the fixed electrodes 15, 16, 17 and
The current flowing between the fixed electrodes 15 and 16 and the fixed electrodes 17 and 18 changes due to the change in the relative position with respect to 18, and the two-dimensional acceleration can be detected by the magnitude and phase of this current change.

Further, since the bridge 23 is provided, the movable range of the beam structure 38 is limited. Therefore, in the normal acceleration range, the sensor normally functions as an acceleration sensor. Further, when an excessive force (acceleration) is applied due to a drop during manufacturing, the beam structure 38 (the beam portions 8 to 11, etc.) tends to be excessively deformed by the impact force, but the bridge 23 causes the excessive deformation. Beams 8, 9, 1 caused by excessive force (acceleration) are suppressed both in the direction parallel to and perpendicular to the substrate surface.
The destruction of 0 and 11 is avoided.

Next, the manufacturing process of the semiconductor acceleration sensor will be described.
This will be described with reference to FIGS. Incidentally, FIG. 6 (a) and FIG.
(A), FIG. 8 (a), FIG. 9 (a), FIG. 10 (a), FIG.
1 (a) and FIG. 12 (a) show the manufacturing process in the AA cross section in FIG. 1, and FIG. 6 (b), FIG. 7 (b), and FIG.
(B), FIG. 9 (b), FIG. 10 (b), FIG. 11 (b), and FIG. 12 (b) show the manufacturing process in the BB cross section in FIG. 6 (c), FIG. 7 (c), FIG. 8 (c), and FIG.
(C), FIG. 10 (c), FIG. 11 (c), FIG. 12 (c)
Shows a manufacturing process on a DD cross section in FIG. 1.

As shown in FIGS. 6A, 6B, and 6C, a P-type silicon substrate 28 is prepared as a semiconductor substrate, and a lower electrode made of an N-type impurity diffusion layer is formed on a predetermined region of its main surface. 29 and the fixed electrodes 15, 16, 17, 18 made of the impurity diffusion layer shown in FIG. 1 are formed, and the silicon nitride film 30 is formed on the entire main surface of the silicon substrate 28. Then, as shown in FIGS. 7A, 7B, and 7C, the first anchor portions 3 and 4 of the beam structure 38 and the anchor portions of the bridge 23 are formed on the entire surface of the silicon substrate 28.
A silicon oxide film 31 as a film is deposited. The silicon oxide film 31 has a predetermined film thickness t1.

Further, as shown in FIGS. 8A, 8B, and 8C, a second film serving as the movable portion 5 of the beam structure 38 and the anchor portion of the bridge 23 is formed on the entire surface of the silicon substrate 28. A polysilicon thin film 32 is deposited. The polysilicon thin film 32 has a predetermined film thickness t2. Then, the polysilicon thin film 32 is patterned into a predetermined shape. At this time, as shown in FIG. 13, the polysilicon thin film 32 is patterned in the shape of the movable portion 5 (beam structure 38) on the silicon oxide film 31, and both sides of the beam portion formation region in the formation portion of the bridge 23 are formed. Is located in.

Subsequently, as shown in FIGS. 9A, 9B, and 9C, the interlayer insulating film 2 is formed on the entire surface of the silicon substrate 28.
A PSG film 33 is deposited as a third film which becomes 0 and becomes a sacrifice layer for bridge formation. This PSG film 3
3 is a polysilicon thin film (see FIG.
(Shown by 32a in (c)). And
As shown in FIGS. 10A, 10B, and 10C, the PSG film 33 is patterned into a predetermined shape. At this time, the opening 34 is formed at the contact portion of the beam structure 38 with the movable portion 5, and the opening 35 for exposing the polysilicon thin film 32 at the bridge forming portion is formed.

Further, as shown in FIGS. 11A, 11B, and 11C, the PSG film 33 including the inside of the openings 34 and 35.
An aluminum thin film 36 as a fourth film is deposited on the above and patterned into a predetermined shape. At this time, it is patterned into the shape of the aluminum wiring 22 in FIG.
3 shape is patterned. In the bridge formation region, the aluminum thin film 36 is arranged so as to be laid over the PSG film 33.

In the step of forming the aluminum thin film 36, the aluminum thin film 36 is less likely to be disconnected at the bridge forming portion. That is, when the silicon oxide film 31 and the polysilicon thin film 32 are not present, the step difference between the aluminum thin film 36 is H1, whereas the step difference between the aluminum thin film 36 due to the provision of the silicon oxide film 31 and the polysilicon thin film 32 is The total film thickness of the films 31 and 32 is reduced by t3 (= t1 + t2), resulting in H2 (= H1-t3). As a result, breakage of the aluminum thin film 36 is unlikely to occur.

Then, as shown in FIGS. 12 (a), 12 (b) and 12 (c), the silicon oxide film 31 and PSG in a predetermined region are formed.
The film 33 is left and the silicon oxide film 31 and the PSG film 33 are removed as a sacrifice layer by etching. At this time, the beam structure forming region (beam portions 8, 9, 10,
11, the weight part 12, the movable electrode parts 12, 13) and the silicon oxide film 31 underneath are removed, and the PSG film 33 on the side surface and the upper surface of the polysilicon thin film 32a is removed in the bridge formation region. Therefore, the beam parts 8, 9,
A space is formed between 10, 11 and the bridge 23.
As a result, the beam structure 38 is formed, and the movable portion 5 becomes movable. In the bridge formation region, the bridge 23 composed of the polysilicon thin film 32, the silicon oxide film 31 under the polysilicon thin film 32, and the aluminum thin film 36.
Is formed.

Thus, in this embodiment, the silicon substrate 2
Silicon oxide film 3 having a predetermined film thickness t1 on the main surface 8
1 (first film) is formed (first step), and the silicon oxide film 3 is formed.
1. A polysilicon thin film 32 (second film) having a predetermined film thickness t2 is formed on both sides of a formation region of the beam structure 38 on 1 and a predetermined portion which is a movable portion of the beam structure 38 (second step), A PSG film 33 (third film) is formed around a predetermined portion which is a movable portion of the beam structure 38 (third step), and PSG is formed.
An aluminum thin film 36 (fourth film) is formed on the film 33 so as to bridge the polysilicon thin film 32 (fourth step), and the silicon oxide film 31 and the beam under the region where the beam structure 38 is formed except the anchor portion are formed. The PSG film 33 around a predetermined portion which is a movable portion of the structure 38 is removed by etching to form the beam structure 38, and the polysilicon thin film 32, the silicon oxide film 31 under the polysilicon thin film 32, and the aluminum. Bridge 23 composed of thin film 36 (movable range limiting member)
Was formed (fifth step).

That is, as shown in FIG. 5, the films 24 and 25 having the predetermined film thickness are formed on both sides of the predetermined portion of the main surface of the silicon substrate 28, which is the movable portion of the beam structure 38.
Film), a PSG film 33 (sacrificial layer) is formed around a predetermined portion that is a movable part of the beam structure 38, and then the film 26 (second film) is formed so as to bridge the films 24 and 25. The film 23 is formed, and the PSG film 33 is removed by etching to form a bridge 23 (movable) which is composed of films 24 and 25 (first film) and a film 26 (second film) that bridges the films 24 and 25. A range control member) is formed.

As a result, the bridge 23 (movable range control member) is formed on the surface of the silicon substrate 1 (semiconductor substrate) on both sides of the movable portion of the beam structure 38, and the films 24 and 25 having a predetermined film thickness t3. (First film) and the films 24 and 2
5 and a film 26 (second film) that bridges 5 together.

In this semiconductor acceleration sensor, the film 2
In this configuration, the step difference of the film 26 is reduced by the thickness of the films 24 and 25, as compared with the step difference when the beam structure 38 is formed only by surrounding the beam structure 38 without providing the films 4 and 25. 26 is less likely to be disconnected. That is, as shown in FIG. 5, when the films 24 and 25 are not provided, the film 2
6 is H1 (the same as H1 shown in FIG. 20), the provision of the films 24 and 25 reduces the step of the film 26 by the film thickness t3 of the films 24 and 25.
(= H1-t3). As a result, breakage of the film 26 is less likely to occur.

The first film is a laminated body of two films 24 and 25, and the two films 24 and 25 are members (anchor parts 3 and 4 and movable part 5) that constitute the beam structure 38. Made of the same material. Therefore, the film can be easily manufactured without using a dedicated film for forming the films 24 and 25. That is, as shown in FIG. 7, the first film 31 has the anchor portion 3,
No. 4 and the same material (silicon oxide film) are formed at the same time, and as shown in FIG.
It is made of the same material (polysilicon) and is formed simultaneously. Therefore, the manufacturing can be easily performed without increasing the number of processes.

Further, in FIG. 5, the film 26 (second film) is used.
Since it is formed of a wiring material (aluminum), it is easy to manufacture without using a dedicated film for forming the film 26. That is, as shown in FIG. 11, the fourth film 36 was made of a wiring material, and was performed at the same time as the wiring step. Therefore,
Manufacture is easy without increasing the number of processes.

Further, if the film thickness of the wiring is increased in order to prevent the disconnection of the bridge 23 (movable range control member), the thickness of the wiring used for the peripheral circuit is also changed, and there is no process consistency. . Further, if the movable range limiting member is formed by a process different from the wiring, the number of processes is increased and the manufacturing cost is increased. Furthermore, if the beam thickness is reduced, the spring constant of the beam will change and the characteristics of the sensor will change. On the other hand, in the present embodiment, as described above, without increasing the film thickness of the wiring (aluminum) film, without increasing the manufacturing process, and without reducing the film thickness of the movable portion. The semiconductor acceleration sensor can be provided with a movable range limiting member that does not have steps.

An application example of this embodiment will be described below. In the above-described embodiment, the wirings of the movable electrode portions (gate electrode portions) 13 and 14 and the film 26 serving as the anchor portion of the bridge (movable range limiting member) 23 are simultaneously formed by the same member. (Part), the wiring of 15, 16, 17, 18 and the film 26 serving as the anchor portion of the bridge 23 are simultaneously formed by the same member, or the wiring of the movable electrode portions 13, 14 and the fixed electrodes 15, 16, 17, 18 are formed. The wiring and the film 26 serving as the anchor portion of the bridge 23 may be simultaneously formed by the same member.

Further, in the above-mentioned embodiment, the laminated body of the silicon oxide film 24 and the polysilicon film 25 is arranged in a state of being insulated via the silicon nitride film 2. However, as shown in FIG. It is also possible to provide an opening 37 that penetrates the silicon nitride film 2 and the polysilicon film 25 and the lower electrode 27 directly through the opening 37. Also in this case, the bridge 23 and the lower electrode 2
7 and 7 can be made equipotential, and electrostatic attraction can be prevented from occurring in the beam portions 8, 9, 10, and 11.

Further, the bridge 23 which is the movable range limiting member is arranged on each of the four beam portions, but the shape, the configuration position, the number, etc. of the bridge 23 can be arbitrarily changed. For example, the beam portion 8, It may be arranged only at two places such as 11, 9 and 10, or may be constructed so as to cover the entire weight portion 12.

Further, the two films 2 constituting the first film 2
Either one of the films 4 and 25 may be made of the same material as the member forming the beam structure 38. Also in this case, it is possible to suppress the increase in the number of processes and easily perform the manufacturing.

Alternatively, the two films 2 forming the first film
Each of the films 4 and 25 may be made of a material different from that of the member forming the beam structure 38. Furthermore, the bridge 23
26 is a wiring material (aluminum thin film)
Alternatively, a nitride film (SiN film) for passivation that protects the peripheral circuit may be used, and the film 26 may be formed using a passivation film at the same time as the passivation film forming step. Also in this case, an increase in the number of manufacturing processes can be prevented.

Further, in the above-mentioned embodiment, the example in which the semiconductor acceleration sensor is used is shown, but it can be applied to the semiconductor dynamic quantity sensor such as the semiconductor yaw rate sensor and the semiconductor vibration sensor.

[0057]

As described in detail above, according to the invention described in claim 1, it is possible to provide a semiconductor dynamic quantity sensor provided with a movable range limiting member in which disconnection is unlikely to occur.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), the manufacturing can be facilitated. According to the invention of claim 3, claim 1
Alternatively, in addition to the effect of the invention described in 2, the manufacturing can be facilitated.

According to the invention of claim 4, claim 1
The semiconductor dynamic quantity sensor described in 1 can be easily manufactured. According to the invention described in claim 5, the semiconductor dynamical quantity sensor described in claim 3 can be easily manufactured.

According to the invention of claim 6, claim 2
The semiconductor dynamic quantity sensor described in 1 can be easily manufactured. According to the invention described in claim 7, the semiconductor dynamical quantity sensor described in claim 3 can be easily manufactured.

[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.

5 is a sectional view taken along line DD of FIG.

6A, 6B, and 6C are cross-sectional views showing the manufacturing process of the semiconductor acceleration sensor.

7A, 7B, and 7C are cross-sectional views showing the manufacturing process of the semiconductor acceleration sensor.

8A, 8B, and 8C are cross-sectional views showing a manufacturing process of the semiconductor acceleration sensor.

9A, 9B, and 9C are cross-sectional views showing the manufacturing process of the semiconductor acceleration sensor.

10A, 10B, and 10C are cross-sectional views showing the manufacturing process of the semiconductor acceleration sensor.

11A, 11B, and 11C are cross-sectional views showing the manufacturing process of the semiconductor acceleration sensor.

12A, 12B, and 12C are cross-sectional views showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 13 is a plan view showing the manufacturing process of the semiconductor acceleration sensor.

FIG. 14 is a cross-sectional view of a bridge in an application example.

FIG. 15 is a perspective view of a conventional semiconductor acceleration sensor.

FIG. 16 is a plan view of a conventional semiconductor acceleration sensor.

17 is a sectional view taken along line EE of FIG.

18 is a sectional view taken along line FF of FIG.

19 is a sectional view taken along line GG of FIG.

20 is a cross-sectional view taken along line HH of FIG.

[Explanation of symbols]

1 ... Silicon substrate as semiconductor substrate, 8 ... Beam portion, 9 ...
Beam portion, 10 ... Beam portion, 11 ... Beam portion, 13 ... Movable electrode portion as gate electrode portion, 14 ... Movable electrode portion as gate electrode portion, 15 ... Fixed electrode as source / drain portion, 1
6 ... Fixed electrode as source / drain portion, 17 ... Fixed electrode as source / drain portion, 18 ... Fixed electrode as source / drain portion, 23 ... Bridge as movable range limiting member, 24 ... First film Silicon oxide film, 25 ... Polysilicon film, which constitutes the first film, 25 ...
Aluminum thin film as second film, 28 ... Silicon substrate as semiconductor substrate, 31 ... Silicon oxide film as first film, 32 ... Polysilicon thin film as second film, 33 ... Sacrificial layer and third film PSG film, 36 ... Aluminum thin film as fourth film, 38 ... Beam structure

Claims (7)

[Claims] 1. A beam structure is provided on a semiconductor substrate, and displacement of a gate electrode part forming a part of the beam structure due to the action of a mechanical quantity is caused by an impurity diffusion layer formed on the semiconductor substrate. A semiconductor dynamic quantity sensor configured to detect with a current flowing in a drain portion, the semiconductor dynamic quantity sensor extending from the semiconductor substrate so as to surround a movable portion of the beam structure, and a movable range of the gate electrode portion. The movable range limiting member for limiting is formed on the surface of the semiconductor substrate on both sides of the movable portion of the beam structure, and has a first film having a predetermined film thickness, and a second film that bridges the first film. A semiconductor dynamical quantity sensor comprising: a film. 2. The first film is a laminate of two films, and at least one of the two films is made of the same material as a member constituting the beam structure. Semiconductor dynamic quantity sensor. 3. The semiconductor dynamic quantity sensor according to claim 1, wherein the second film is made of a wiring material or a passivation film. 4. A beam structure is provided on a semiconductor substrate, and a movable range control member that extends from the semiconductor substrate and surrounds a movable portion of the beam structure is provided. The displacement of the gate electrode portion forming a part of the beam structure is detected by the current flowing through the source / drain portion formed of the impurity diffusion layer formed on the semiconductor substrate, and the movable range limiting member is used to detect the gate electrode portion. Is a method for manufacturing a semiconductor dynamical amount sensor, in which the movable range of the beam structure is limited, and a first film having a predetermined film thickness on both sides of a predetermined portion that is a movable portion of the beam structure on the main surface of the semiconductor substrate After forming the film, a sacrificial layer is formed around a predetermined portion which is a movable part of the beam structure, and then a second film is formed so as to bridge the first film, and further the sacrificial layer is formed. Etch The method of manufacturing a semiconductor dynamic quantity sensor is characterized in that so as to form a movable range restriction member comprising a second membrane that spans the first film and its first film is grayed removed. 5. The method for manufacturing a semiconductor dynamical amount sensor according to claim 4, wherein the second film is made of a wiring material or a passivation film, and the film is formed in a wiring process or a passivation film formation process. 6. A beam structure is provided on a semiconductor substrate, and a movable range control member that extends from the semiconductor substrate and surrounds a movable portion of the beam structure is provided. The displacement of the gate electrode portion forming a part of the beam structure is detected by the current flowing through the source / drain portion formed of the impurity diffusion layer formed on the semiconductor substrate, and the movable range limiting member is used to detect the gate electrode portion. Is a method for manufacturing a semiconductor dynamical amount sensor so as to limit the movable range of the first substrate, and a first step of forming a first film having a predetermined film thickness on the main surface of the semiconductor substrate; A second step of forming a second film having a predetermined film thickness on both sides of the beam structure formation region and a predetermined portion which is a movable portion of the beam structure; and a predetermined portion which is a movable portion of the beam structure. A third membrane around the A third step of forming, and a fourth step so as to bridge the second film on the third film.
A fourth step of forming a film, a first film below a region where the beam structure is formed excluding an anchor portion, and a third process around a predetermined part which is a movable part of the beam structure
A fifth step of removing the film by etching to form a beam structure and forming a movable range limiting member including the second film and the first film and the fourth film under the second film. A method of manufacturing a semiconductor dynamical quantity sensor characterized by the above. 7. The semiconductor mechanics according to claim 6, wherein the fourth film in the fourth step is made of a wiring material or a passivation film, and the fourth step is performed simultaneously with the wiring step or the passivation film forming step. Method of manufacturing a quantity sensor.