JP2001119040A - Semiconductor amount-of-dynamics sensor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor amount-of-dynamics sensor for readily securing a closing property in a cap when protecting the movable part of beam structure with the cap. SOLUTION: A sensor element part, consisting of a beam structure 2 as a movable part, fixed electrodes 9a-9c, and the like, is provided on the upper surface of a silicon substrate 17, an insulated and separated conductive thin film 19 is embedded between a sensor element part and the substrate 17, a wiring pattern and lower electrodes 22-25 formed by the conductive thin film 19 are electrically connected to electrode take-out parts 27a-27d arranged being nearly flush with the sensor element part, at the same time, a flat part 30 without steps so that the sensor element part is surrounded is formed between the electrode draw-out part on the substrate 17 and the sensor element, one surface side of a cap substrate 200 with a recessed part 202 at one surface side is joined to the flat part 30, and the sensor element part is covered with the recessed part 202 for protection.

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 movable portion having a beam structure, and more particularly to a semiconductor dynamic quantity sensor for detecting a dynamic quantity such as acceleration, yaw rate, and vibration, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art In general, a basic principle of a dynamic quantity sensor such as an acceleration sensor is to measure a displacement or a force when a dynamic quantity acts on a mass portion (movable portion) connected to a beam using a beam called a flexure beam. It is to be. In recent years, there has been an increasing demand for miniaturization, low cost, and high reliability of dynamic quantity sensors such as acceleration sensors used for automobile suspension control, airbags, and the like. In order to meet these demands, there has been proposed an S-port as described in JP-A-9-211022.
There is a semiconductor physical quantity sensor using an OI substrate and a manufacturing method thereof.

In this device, a beam structure as a movable portion made of single-crystal silicon and a fixed electrode disposed opposite to a movable electrode of the beam structure are provided on an upper surface of the substrate. An opening in which a laminate of a lower insulating thin film, a conductive thin film, and an upper insulating thin film is arranged, and a wiring or an electrode is formed by the conductive thin film, and the wiring or the electrode is formed in the upper insulating thin film. This is electrically connected to an electric connection member (bonding pad) disposed on the substrate through the portion.

That is, an SOI (silicon-on-insulator) substrate (embedded SOI substrate) using a buried conductive thin film (for example, a polysilicon layer) is used as the wiring on the substrate side, whereby the SOI substrate is insulated and separated by an insulator. In addition, a highly reliable semiconductor dynamic quantity sensor can be realized by forming a beam structure made of single crystal silicon with a trench groove.

[0005]

In general, in the above-described semiconductor dynamic quantity sensor, the movable portion is covered with a cap to protect the movable portion, and an inert gas or vacuum is applied around the movable portion. In order to protect the movable part from water pressure and water flow when dicing and cutting into chips from the wafer state, it is possible to prevent resin from entering the inside of the movable part when molding the chip with resin. (For example, Japanese Patent Laid-Open No. 10-1125)
No. 48).

Here, in the above-described semiconductor dynamic quantity sensor using the conventional SOI substrate, a step due to a trench or the like exists between the beam structure or the fixed electrode and the electric connection member. For example, in the structure shown in FIG. 1 of Japanese Patent Application Laid-Open No. 9-211022, a trench is provided between the bonding pad (reference numeral 34) and the beam structure (reference numeral 2) as a movable portion. Exists.

[0007] When providing a protective cap for protecting the movable portion, the above-mentioned step is present at the joint between the sensor surface and the cap, and a gap is generated at the joint. For this reason, there arises a problem that a foreign substance is mixed into the cap from the gap and that sealing with an inert gas or vacuum cannot be performed. That is, there arises a problem that the hermeticity of the joined protective cap is insufficient.

In view of the above problems, an object of the present invention is to protect a movable portion of a beam structure with a cap.
It is an object of the present invention to provide a semiconductor physical quantity sensor that can easily ensure the tightness of a cap, and to provide a manufacturing method that can appropriately manufacture such a semiconductor physical quantity sensor.

[0009]

First, according to the first aspect of the present invention, a beam structure (2) as a movable portion and fixed electrodes (9a to 9c, 11a to 11a) are provided on an upper surface of a first substrate (17). 11
c, 13a to 13c, 15a to 15c) and a lower insulating thin film (18a, 18b), a conductive thin film (19), and an upper insulating thin film on the upper surface of the first substrate. Placing a laminate (21) with (20),
Wiring (22, 23, 25) or electrode (24) formed of a conductive thin film, and the wiring or electrode is disposed on the first substrate through an opening formed in the upper insulating thin film. In the semiconductor physical quantity sensor electrically connected to (27a to 27d), a flat surface having no step between the electric connection member and the sensor element portion on the first substrate so as to surround the sensor element portion. Forming a flat portion (30) having
Second substrate (200) having recess (202) on one side
Are joined together to cover and protect the sensor element portion with the concave portion.

According to the present invention, by using a conductive thin film insulated and separated by an insulator as a wiring or an electrode, the wiring or the electrode can be embedded in the sensor. Therefore, even if a flat portion is formed between the sensor element portion and the electrical connection member so as to surround the sensor element portion, the wiring or the electrode can pass under the flat portion, and the sensor element portion and the electric connection member can be electrically connected. Electrical connection with the connection member can be secured.

Then, for a flat portion having a flat surface,
Since the second substrate as the protective cap having the concave portion is joined, no gap is generated at the joint between the second substrate and the flat portion. Therefore, according to the present invention, it is possible to provide a semiconductor dynamic quantity sensor that can easily secure the tightness of the inside of the cap when protecting the movable portion with the cap.

Here, as in the invention of claim 2, the conductive thin film (19) protrudes to the upper side of the upper insulating thin film through an opening formed in the upper insulating thin film (20). (10a-10c, 12a-12c, 14a-
14c, 16a to 16c) and fixed electrodes (9a to 9c, 11a to 11c, 13a)
To 13c, 15a to 15c) can be adopted.

According to a third aspect of the present invention, a movable electrode (7a) extending in parallel with each other is provided on the upper surface of the first substrate (17).
To 7c, 8a to 8c), a beam structure (2) as a movable portion, and first fixed electrodes (9a to 9c, 13a to 13c) disposed opposite to one side surface of each movable electrode, respectively.
And second fixed electrodes (11a to 11c, 15a to 15c) arranged opposite to each other on the other side surface of each movable electrode, and the first fixed electrode is formed by the movable electrode of the beam structure and the first fixed electrode. A so-called differential capacitance type semiconductor dynamic quantity sensor in which a capacitor is formed and a second capacitor is formed by the movable electrode of the beam structure and the second fixed electrode.

According to the present invention, in this differential capacitance type semiconductor dynamic quantity sensor, the lower insulating thin films (18a, 18b) and the conductive thin film (1) are formed on the upper surface of the first substrate.
9) and a laminated body (21) of the upper insulating thin film (20) are arranged, and each of the wiring patterns (22, 23, 2) of the movable electrode, the first fixed electrode, and the second fixed electrode is formed by the conductive thin film.
5), and these wiring patterns are electrically connected to the electric connection members (27b, 27c, 27d) arranged on the first substrate through the openings formed in the upper insulating thin film. Further, a flat portion (30) is provided between the sensor element portion constituted by the beam structure and each fixed electrode and the electric connection member, as in the above-mentioned claim 1, and the second substrate (200) It is characterized by joining.

[0015] According to the third aspect of the present invention, the first aspect is also provided.
Similarly to the invention of the third aspect, it is possible to provide a semiconductor dynamic quantity sensor which can secure electrical connection between the sensor element portion and the electrical connection member, and can easily secure tightness inside the cap when protecting the movable portion with the cap.

Here, the flat portion (30) can be formed on the upper insulating thin film (20). The flat portion is made of the same material as that of the beam structure (2). This makes it possible to form the flat portion more easily than when another material is used. Further, if the space between the sensor element portion and the concave portion (202) of the second substrate (200) is filled with an inert gas or is in a vacuum state as in the invention of the eighth aspect, the sensor element Deterioration (deterioration, etc.) of the part can be maintained at a higher level.

According to the ninth to thirteenth aspects of the present invention, the semiconductor physical quantity sensor according to the first and third aspects can be appropriately manufactured. That is, between the first semiconductor substrate (40) and the second semiconductor substrate (48),
A first insulator thin film (43), a conductive thin film (45), a second
By forming a sandwich structure of the insulator thin films (46a, 46b), a buried SOI substrate (a bonded first and second semiconductor substrate) having a conductive thin film which is insulated and separated as wiring is formed. it can.

In the method of manufacturing the buried SOI substrate, unnecessary patterns in the first semiconductor substrate are removed from the completed buried SOI substrate to obtain a desired shape. The eighth step and the manufacturing method according to claim 10 can be realized by the first step of forming a groove (60a) in a predetermined region of the first semiconductor substrate (40) before bonding the buried SOI substrate. It is.

Further, the first semiconductor substrate (40) is polished to a desired thickness, and the flat portion (30) is formed on the surface of the first semiconductor substrate by the step of forming the flat portion (30). Can be formed. Then, with respect to the flat portion of the embedded SOI substrate on which the beam structure (movable structure) is formed, the movable structure is covered with the concave portion (202).
Through the step of bonding the third semiconductor substrate (200) via the bonding film (201), the semiconductor physical quantity sensor having the configuration according to the first and third aspects can be formed.

As described above, according to the ninth to thirteenth aspects of the present invention, a semiconductor dynamic quantity sensor capable of easily ensuring the tightness of the inside of the cap when protecting the movable portion of the beam structure with the cap is suitable. Can be provided. In particular, according to the invention as set forth in claims 11 to 13, a semiconductor dynamic quantity sensor having the effect of the invention of claim 11 can be appropriately manufactured.

Note that the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) In the first embodiment, the semiconductor dynamic quantity sensor of the present invention is embodied as a semiconductor acceleration sensor, more specifically, a servo-controlled differential capacitive semiconductor acceleration sensor. It will be described as having done.

FIG. 1 is a plan view of the semiconductor acceleration sensor according to the present embodiment. FIG. 2 is an enlarged view of the central portion (sensor element portion) of FIG. 1 and illustrates the beam structure and the anchor portions of the fixed electrode omitted in FIG. Also,
3 is a sectional view taken along line AA in FIG. 1, FIG. 4 is a sectional view taken along line BB in FIG. 1, FIG. 5 is a sectional view taken along line CC in FIG. 1, and FIG.
FIG. 7 is a perspective view taken along the line AA in FIG. 1. 1 and 2, each anchor portion, each wiring pattern, and the lower electrode are shown by broken lines.

As shown in FIG. 3, a beam structure (movable part) 2 made of single crystal silicon (single crystal semiconductor material) is arranged on the upper surface of the substrate 1. As shown in FIGS. 2 and 3, the beam structure 2 is bridged by two anchor portions 3 a and 3 b protruding from the substrate 1, and is disposed at a predetermined interval on the upper surface of the substrate 1. I have. The anchor portions 3a and 3b are made of a polysilicon thin film.

Between the anchor 3a and the anchor 3b, the beam 4 and the anchor 3b are located near the anchor 3a.
A beam portion 5 is provided closer thereto, and a rectangular mass portion (mass portion) 6 is provided between the beam portions 4 and 5. The mass portion 6 is provided with a through-hole 6a penetrating vertically, and the through-hole 6a makes it easier for the etchant to enter the sacrificial layer to be described later.

Further, from one side surface (left side surface in FIG. 1) of the mass section 6, three movable electrodes 7a and 7
b and 7c protrude. The movable electrodes 7a to 7c are rod-shaped and extend in parallel at equal intervals. Further, three movable electrodes 8a, 8b, 8c protrude from the other side surface (the right side surface in FIG. 1) of the mass portion 6. The movable electrodes 8a to 8c have a bar shape and extend in parallel at equal intervals. Here, the beam portions 4 and 5, the mass portion 6, and the movable electrodes 7 a to 7 c and 8 a to 8 c are movable by etching and removing a part of the sacrifice layer oxide film 37. Thus, the beam structure 2 has two comb-shaped movable electrodes.

On the upper surface of the substrate 1, three first fixed electrodes 9a, 9b, 9c are fixed.
Is made of single crystal silicon (single crystal semiconductor material). First
Fixed electrodes 9a to 9c are supported by anchor portions 10a, 10b, and 10c protruding from the substrate 1 side, and are arranged to face one side surface of each movable electrode (rod-shaped portion) 7a to 7c of the beam structure 2. Have been.

On the upper surface of the substrate 1, three second fixed electrodes 11a, 11b and 11c are fixed, and the fixed electrodes 11a to 11c are made of single crystal silicon. The second fixed electrodes 11a to 11c are supported by anchor portions 12a, 12b, and 12c protruding from the substrate 1, and face the other side surfaces of the movable electrodes (bar-shaped portions) 7a to 7c of the beam structure 2. It is arranged.

Similarly, the first fixed electrodes 13a, 13b, 13c and the second fixed electrodes 15a,
15b and 15c are fixed, and the fixed electrodes 13a to 13c are fixed.
c and 15a to 15c are made of single crystal silicon. The first fixed electrodes 13a to 13c are anchor portions 14a, 14
b, 14c, and are arranged to face one side surface of each of the movable electrodes (bar portions) 8a to 8c of the beam structure 2. The second fixed electrodes 15a to 15d are supported by the anchor portions 16a, 16b, and 16c, and are disposed so as to face the other side surfaces of the movable electrodes (rod portions) 8a to 8c of the beam structure 2. I have.

Here, as shown in FIGS. 3 to 7, the substrate 1 is formed on a silicon substrate (first substrate according to the present invention) 17 via a bonding thin film 39 via a lower insulating thin film. 18a,
18b, a conductive thin film 19, and an upper insulating thin film 20. That is, the laminated body 21 of the lower insulating thin films 18a and 18b, the conductive thin film 19, and the upper insulating thin film 20 is arranged on the upper surface of the silicon substrate 17, and the conductive thin film 19 is insulated. Body thin film 18
a, 18b, and 20 are embedded.

The lower insulating thin films 18a and 18b are composed of a silicon oxide film and a silicon nitride film (in this example, the thin film 18a is a silicon nitride film and the thin film 18b is a silicon oxide film), and the upper insulating thin film 20 is a silicon nitride film. It is formed of a film and formed by a CVD method or the like. The conductive thin film 19 is made of a polysilicon thin film doped with an impurity such as phosphorus.

The conductive thin film 19 forms the three wiring patterns 22, 23 and 25 shown in FIG. 1 and also forms the lower electrode (fixed electrode for canceling electrostatic force) 24. 1 and 2, these wirings and electrodes 22 to 25 are indicated by broken lines. First, the wiring pattern 22 includes the first fixed electrodes 9a, 9b, 9c, and 1
The wirings 3a, 13b, and 13c extend in a belt shape as shown in FIG.

Similarly, the wiring pattern 23 includes the second fixed electrodes 11a, 11b, 11c and 15a, 15b, 15c.
, And extend in a belt shape as shown in FIG.
The wiring pattern 25 includes movable electrodes 7a to 7c and 8a.
To 8c, and extend in a belt shape as shown in FIG. Further, the lower electrode 24 is formed in a region facing the beam structure 2 on the upper surface of the substrate 1 and extends in a belt shape as shown in FIG.

As shown in FIG. 2, a first capacitor C1 (capacitance C1) is provided between the movable electrodes 7a to 7c of the beam structure 2 and the first fixed electrodes 9a to 9c. The movable electrodes 7a to 7c of the beam structure 2 and the second fixed electrodes 11a to 11c
11c and a second capacitor C2 (capacitance C2)
Is formed. Similarly, the movable electrodes 8 a to 8 of the beam structure 2
c and the first fixed electrodes 13a to 13c, the first capacitor C1 is provided between the movable electrodes 8a to 8c of the beam structure 2.
A second capacitor C2 is formed between the second fixed electrodes 15a to 15c.

On the upper surface of the substrate 1, an electrode extraction portion (electric connection member in the present invention) made of single crystal silicon is provided.
a, 27b, 27c, and 27d are formed, and each of the electrode extraction portions 27a to 27d is an anchor portion 28 protruding from the substrate 1.
a, 28b, 28c, 28d.

As shown in FIG. 5, openings 29a, 29b, 29c and 30b are formed in the upper insulating thin film 20, and the above-described anchor portions (impurity-doped polysilicon) are formed in the openings 29a, 29b and 29c. ) 10a to 10c are arranged. An anchor (impurity-doped polysilicon) 28b is arranged in the opening 30b. Therefore, the openings 29a to 29c and the anchor 1
The wiring pattern 22 and the first fixed electrodes 9a to 9c are electrically connected through 0a to 10c, and the wiring pattern 22 and the electrode extraction portion 27b are electrically connected through the opening 30b and the anchor portion 28b. I have. The same applies to the electrical connection configuration between the first fixed electrodes 13a to 13c, the wiring pattern 22, and the electrode extraction portion 27b.

As shown in FIG. 6, openings 31a, 31b, 31c and 30d are formed in the upper insulating thin film 20. The anchor portions (impurity-doped polysilicon) 12a to 12c described above are formed in the openings 31a to 31c.
Further, the above-mentioned anchor portion (impurity-doped polysilicon) 28d is arranged in the opening 30d. Therefore,
Openings 31a-31c and anchors 12a-12c
Through the wiring pattern 23 and the second fixed electrodes 11a to 11a.
11c is electrically connected, and the wiring pattern 23 and the electrode extraction portion 27d are electrically connected through the opening 30d and the anchor portion 28d. The second fixed electrodes 15a to 15c, the wiring pattern 23, and the electrode extraction portion 2
The same applies to the electrical connection configuration with 7d.

As shown in FIG. 3, openings 32a, 32b and 30c are formed in the upper insulating thin film 20. The above-mentioned anchor portions (impurity-doped polysilicon) 3a, 3b are provided in the openings 32a, 32b.
The anchor portion (impurity-doped polysilicon) 28c described above is arranged in c. Therefore, the openings 32a,
32b, the wiring pattern 25, the beam structure 2, the mass part 6, and the movable electrodes 7a to 7a through the anchor parts 3a and 3b.
c, 8a to 8c are electrically connected, and the wiring pattern 25 and the electrode extraction portion 27c are electrically connected through the opening 30c and the anchor portion 28c.

Similarly to the wiring patterns 22, 23 and 25, the lower electrode 24 formed in a region facing the beam structure 2 on the upper surface of the substrate 1 also has an upper insulating thin film 20.
Through an opening (not shown) and an anchor portion (impurity-doped polysilicon) 28a.

Here, as shown in FIG.
2 and the lower electrode 24 intersect, and the wiring patterns 23 and 25
And intersect. As shown in FIG. 3, one of the intersections is not short-circuited by the bridge 26 formed by the opening formed in the upper insulating thin film 20 and the anchors (impurity-doped polysilicon) 26a and 26b. As shown in FIG.

As described above, the substrate 1 includes the wiring patterns 22, 23, 25 and the lower electrode 24 made of polysilicon.
Is embedded under the SOI layer, and this structure is formed by using a surface micromachining technique. As shown in FIGS. 1, 3, 5, and 6, pad electrodes (bonding pads) 34a, 34b, 34c, 34d made of an aluminum thin film are provided on the upper surfaces of the electrode extraction portions 27a, 27b, 27c, 27d. Are provided respectively.

Therefore, in this embodiment, the lower insulating thin films 18a and 18b, the conductive thin film 19, and the upper insulating thin film 2 are formed on the upper surface of the silicon substrate (first substrate) 17.
0, and the respective wiring patterns 22, 23, 25 of the movable electrode, the first fixed electrode, and the second fixed electrode are formed by the conductive thin film 19, and these wiring patterns are insulated from the upper layer. Through the openings formed in the body thin film 20, the electrodes are electrically connected to electrode extraction portions (electric connection members) 27a to 27d and pad electrodes 34a to 34d arranged on the silicon substrate 17.

In this embodiment, the conductive thin film 19 is provided with anchor portions 10a to 10c as protrusions protruding to the upper side of the upper insulating thin film 20 through openings formed in the upper insulating thin film 20. , 12a-12c,
14a to 14c and 16a to 16c, and each fixed electrode 9a to 9c, 1
1 a to 11 c, 13 a to 13 c, and 15 a to 15 c are connected to the conductive thin film 19.

In such a semiconductor acceleration sensor, the movable electrodes 7a to 7c of the beam structure 2 and the first fixed electrodes 9a to 9c
9c and the capacitance C1 of the first capacitor formed between
(And the movable electrodes 8a to 8c and the first fixed electrodes 13a to 13c)
13c and the capacitance C of the first capacitor formed between
1) and the movable electrodes 7a to 7c of the beam structure 2 and the second
Of the second capacitor formed between the fixed electrodes 11a to 11c (and the movable electrodes 8a to 8c and the second
The acceleration acting on the beam structure 2 can be detected based on the capacitance C2) of the second capacitor formed between the fixed electrodes 15a to 15c. More specifically, two differential capacitances are formed by the movable electrode and the fixed electrode, and the servo operation is performed so that the two capacitances become equal.

Further, by making the potential of the beam structure 2 and the lower electrode 24 equal, the electrostatic force generated between the beam structure 2 and the substrate 1 is canceled. That is, by connecting the lower electrode 24 and the wiring pattern 25 connected to the beams 4, 5 and the mass 6 through the anchors 3a, 3b externally, the electric potential can be made equal. Beam part 4, 5
In addition, the mass portion 6 can be prevented from attaching to the substrate 1 due to electrostatic force. That is, since the beam structure 2 is insulated from the silicon substrate 17, the beam structure 2 is also insulated from the substrate 1 by a slight potential difference between the beam structure 2 and the silicon substrate 17.
Attempt to adhere to the side 7 can be prevented.

Further, in the present embodiment, the beam structure 2 and the fixed electrodes 9a to 9c, 11a to 11c, 13a to 1
3c and 15a to 15c constitute a sensor element unit as a detection unit. 1 and 3
-As shown in FIG. 7, the pad electrode 34a on the substrate 1
A ring-shaped flat portion 30 made of single crystal silicon (single crystal semiconductor material) is formed between the sensor element portion and the sensor element portion so as to surround the sensor element portion. The flat portion 30 has a flat surface with no steps.

The flat portion 30 is formed on the upper insulating thin film 2.
In the present example, it is the same layer as the layer on which the beam structure 2 is formed (ie, the same material as the constituent material of the beam structure). The flat portion 30 may be a layer formed of a different material. Further, in a portion corresponding to the flat portion 30, the upper insulating thin film 20 is formed thicker and the upper insulating thin film 20 is formed.
May be configured as a flat surface, and the upper insulating thin film 20 itself may be configured as a flat portion.

The recess 20 is located at a position facing the sensor element on one side with respect to the flat portion 30.
Substrate (second substrate in the present invention) 2 having
00 are bonded via the bonding film 201. Here, in each figure, 203 indicates a joint portion of the cap substrate 200, and in FIG. 1, the cap substrate 200 and the joint portion 203 are indicated by two-dot chain lines for convenience. In addition, the flat part 30
It suffices that at least the joint 203 has a flat surface.

The cap substrate 200 is made of a silicon substrate, and has one surface side of the cap member 200 (the concave surface side).
Is formed of a thin film such as Ti or Au. The bonding film 201 and the surface of the flat portion 30 are bonded by eutectic bonding. This is performed by pressing the cap substrate 200 against the flat portion 30 while pressing.

In this way, the sensor element portion is covered and protected by the concave portion 202 of the cap substrate 200.
Here, since the concave portion 202 is formed, the sensor element portion and the cap substrate 200 are not in contact with each other.
The hollow portion 204 between the sensor element portion and the concave portion 202 is filled with an inert gas (or is in a vacuum state), so that the detection sensitivity of the sensor can be increased and the characteristics can be stabilized. Is considered. In this example, FIG.
As shown in (1), a communication groove 205 is formed in the cap substrate 200 for filling with an inert gas or vacuum evacuation, and the communication groove 205 is sealed with an adhesive or the like.

As described above, by using the wiring patterns 22, 23, 25 and the lower electrode 24 separated from each other by the insulator,
The pad electrodes (bonding pads) 34a to 34d can be taken out from one end of the substrate surface, and the ring-shaped flat portion 30 for joining the cap substrate 200 can be formed. It can be made easier.

Next, the detection principle of this acceleration sensor is shown in FIG.
This will be described with reference to FIG. Movable electrodes 7a to 7c (8a to 8c)
Are fixed electrodes 9a to 9c (13a to 13c) and 11 on both sides.
Located at the center of a to 11c (15a to 15c), the capacitances C1 and C2 between the movable electrode and the fixed electrode are equal. Also,
Movable electrodes 7a to 7c (8a to 8c) and first fixed electrode 9
The voltage V1 is applied between the movable electrodes 7a to 7c (8a to 8c) and the second fixed electrodes 11a to 9c (13a to 13c).
The voltage V2 is applied between 11c (15a to 15c).

When no acceleration occurs, V
1 = V2, and the movable electrodes 7a to 7c (8a to 8c) are fixed electrodes 9a to 9c (13a to 13c) and 11a to 11c.
c (15a to 15c) with the same electrostatic force. Here, the acceleration acts in a direction parallel to the substrate surface,
When the movable electrodes 7a to 7c (8a to 8c) are displaced, the distance between the movable electrode and the fixed electrode changes, and the capacitance C1,
C2 is not equal.

At this time, so that the electrostatic force becomes equal,
For example, the movable electrodes 7a to 7c (8a to 8c) are
If it is displaced to the side of a to 9c (13a to 13c), the voltage V1 decreases and the voltage V2 increases. Thus, the movable electrodes 7a to 7c (8a to 8c) are pulled toward the fixed electrodes 11a to 11c (15a to 15c) by the electrostatic force. The movable electrodes 7a to 7c (8a to 8c) return to the center position and the capacitance C
If C1 and C2 are 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, the first capacitor C1 and the second capacitor
In the capacitor C2, the voltage of the fixed electrodes forming the first and second capacitors C1 and C2 is controlled so that the movable electrode is not displaced with respect to the displacement due to the action of the physical quantity. Detect acceleration.

Next, the manufacturing process of this acceleration sensor is shown in FIG.
This will be described with reference to FIG. 8 to 13 correspond to FIG.
FIG. 7 is a schematic cross-sectional view showing a manufacturing process using the DD cross section (that is, the cross section shown in FIG. 6).

First, as shown in FIG. 8A, a single crystal silicon substrate (finally, a beam structure 2, fixed electrodes 9a to 9c, 11a to 11c, and 13a to 1c) as a first semiconductor substrate.
3c, 15a to 15c, and the flat portion 30) are prepared, and alignment marks and
A groove A having the same depth as the desired thickness is formed so that the thin film structure can be used as a mark for detecting an end point for obtaining the desired thickness. Then, a silicon oxide film as a sacrificial layer thin film (finally, a sacrificial layer oxide film 37) is formed on the silicon substrate 40.
Is formed by thermal oxidation, CVD, or the like. Then, a silicon nitride film (first insulating thin film, which eventually becomes the upper insulating thin film 20) 43 serving as an etching stopper at the time of etching the sacrificial layer is formed.

Thereafter, as shown in FIG. 8B, openings 44a to 44g are formed in the anchor portion formation region by dry etching or the like through photolithography with respect to the stacked body of the silicon oxide film 41 and the silicon nitride film 43. Form. The openings 44a to 44g are for connecting the beam structure and the substrate (lower electrode), and for connecting the fixed electrode and the electrode extraction portion to the wiring pattern.

Subsequently, on the silicon nitride film 43 including the openings 44a to 44g, a polysilicon thin film 45 (which eventually becomes the conductive thin film 19) to be a conductive thin film is formed. And a wiring pattern 45a, a lower electrode 45b, and an anchor portion 45c are formed in predetermined regions on the silicon nitride film 43 through photolithography. These formed portions 45a to 45c finally become the respective wiring patterns, lower electrodes, and anchor portions shown in FIGS.

Further, as shown in FIGS. 9A and 9B,
On the silicon nitride film 43 including on the polysilicon thin film 45, a silicon nitride film (finally becoming the lower insulator thin film 18a) 46a as a second insulator thin film, and a silicon oxide film 46b (finally lower insulator film) The insulating thin film 18b is formed by a CVD method or the like.

Further, as shown in FIG. 10A, a polysilicon thin film 47 as a bonding thin film is formed on the silicon oxide film 46b, and the polysilicon thin film 47 (finally, the bonding thin film 39) is formed. The surface is flattened by mechanical polishing or the like for bonding. Then, FIG.
As shown in FIG. 3, a single crystal silicon substrate 48 different from the silicon substrate 40 is prepared, and the surface of the polysilicon thin film 47 is
And a silicon substrate 48 as a semiconductor substrate.

Further, as shown in FIG. 11A, the silicon substrates 40 and 48 are turned upside down, and the silicon substrate 40 side is subjected to mechanical polishing or the like to obtain a desired thickness (for example, 10 to 20).
μm). At this time, the end point for obtaining a desired thickness can be detected by thinning the film until the groove A previously formed as the alignment mark is seen. Also,
By this polishing, the polished surface of the silicon substrate 40 becomes a flat surface without any step, and the flat portion 30 is formed.

Next, as shown in FIG. 11B, an interlayer insulating film 51 is formed, and a contact hole 52 is formed by photolithography and dry etching. Further, an aluminum electrode (corresponding to the pad electrodes 34a to 34d) 53 is formed through film formation and photolithography.

Thereafter, as shown in FIG. 12A, a groove is formed in the silicon substrate 40 by photolithography at a constant width by trench etching to form a groove pattern 49 for forming a beam structure. I do. As described above, the groove pattern 49 is formed in the unnecessary region of the silicon substrate 40, and the unnecessary region is removed to obtain a desired shape. In this step (the step of removing unnecessary regions in the silicon substrate 40 to have a desired shape), the photomask can be accurately aligned using the groove A formed in the previous step.

Thereafter, as shown in FIG. 12B, the silicon oxide films 41 and 51 are removed by etching with an HF-based etchant to make the beam structure having the movable electrode portions 8a to 8c movable. That is, the silicon oxide film 41 in a predetermined region is removed by sacrifice layer etching using an etchant, so that the silicon substrate 40 has a movable structure. At this time, in order to prevent the movable portion from sticking to the substrate during the drying process after the etching, a sublimation agent such as balazichlorobenzene is used.

In this step (a step of removing the silicon oxide film 41 in a predetermined region by sacrifice layer etching using an etchant to make the silicon substrate 40 a movable structure)
Since the anchor portion 45c of the movable portion is made of a conductive thin film (polysilicon), the etching stops at the anchor portion 45c, and there is no variation. That is, in this example in which a silicon oxide film is used as the sacrificial layer thin film, a polysilicon thin film is used as the conductive thin film, and an HF-based etchant is used, the silicon oxide film dissolves in HF but the polysilicon thin film does not. Therefore, there is no need to accurately control the concentration and temperature of the HF-based etchant, or to perform the end of the etching with accurate time management, thereby facilitating the manufacture.

That is, when etching the sacrificial layer, the SO
In the case of using the I substrate, the length of the beam changes depending on the etching time. However, in this embodiment, the etching is selectively terminated when the anchor portion is etched regardless of the etching time. The length is always constant.

Since the anchor portion can be formed in this manner, it is not necessary to control the end point by time control in the sacrifice layer etching step when releasing the beam structure, thereby facilitating the control of the spring constant and the like. It becomes possible. Through the above steps, the servo control type acceleration sensor can be formed by using the embedded SOI substrate and forming the wiring pattern 45a and the lower electrode 45b by insulator separation.

Further, in this embodiment, as shown in FIG. 13, a cap substrate 200 as a third semiconductor substrate is bonded to the flat portions 30 of the bonded silicon substrates 40 and 48. However, in the cap substrate 200, a concave portion 202 is formed by performing dry etching or wet etching on one surface side of the silicon substrate. Note that the recess 202 is formed in the cap substrate 20.
It may be perpendicular or oblique to 0.

Then, a bonding film 201 made of a Ti or Au thin film or the like is formed on one surface of the cap substrate 200 (the surface on which the concave portion is formed) by vapor deposition, sputtering, plating, or the like. Thus, the concave portion 202 and the bonding film 201 are formed on one surface side.
Is formed.

Then, the cap substrate 200 is attached to the bonding film 2 so that the movable portion is covered with the concave portion 202 with respect to the flat portion 30 of the bonded silicon substrates 40 and 48.
01 (third semiconductor substrate bonding step).
That is, the silicon substrate 40 and the bonding film 201 are eutectic bonded by bringing the bonding film 201 into contact with the flat surface (the flat portion 30) of the silicon substrate 40 and pressing the same.

The third semiconductor substrate bonding step comprises:
It is preferable that the process be performed in an inert gas atmosphere formed by filling an inert gas into a sealed container or in a vacuum atmosphere formed by evacuating the vacuum chamber. As a result, the cavity 204 in the recess 202 is filled with an inert gas (or vacuum).
Thus, the configuration takes into account the enhancement of the detection sensitivity of the sensor, the stabilization of characteristics, and the like.

Here, in this example, as shown in FIG. 1, a communication groove 205 is formed in the cap substrate 200. Before the third semiconductor substrate bonding step is performed, for example, in the tenth step of forming the concave portion 202, the communication groove 205 is connected to the silicon substrate constituting the cap substrate 200 in advance inside and outside the concave portion 202. This can be performed by forming a groove. By using the communication groove 205, the interior of the cavity 204 can be made an inert gas atmosphere or a vacuum atmosphere even when the third semiconductor substrate bonding step is performed in the air.

That is, after performing the third semiconductor substrate bonding step, the inside of the concave portion 202 is filled with an inert gas through the communication groove 205, and then the communication groove 205 is sealed, whereby the cavity portion is formed. 204 is filled with an inert gas. Further, after performing the third semiconductor substrate bonding step, the inside of the concave portion 202 is evacuated to a vacuum through the communication groove 205, and then the communication groove 205 is sealed to form the cavity 204.
Is in a vacuum state. The communication groove 205 may be sealed with an adhesive or the like.
, The communication groove 205 may be crushed and sealed.

Through the above steps, the semiconductor acceleration sensor shown in FIG. 1 and the like is completed. After that, a dicing cut process is performed using a dicing blade or the like to divide the sensor into chips. In this dicing cut, the substrate 1 on the sensor side on which the beam structure 2 is formed and the cap substrate 200 may be cut simultaneously, or the cap substrate 200 may be cut first, and then the sensor side. The substrate 1 may be cut.

Incidentally, the semiconductor acceleration sensor of the present embodiment has the following features (a) to (f).

(A) The beam structure 2 is disposed at a position spaced apart from the upper surface of the substrate 1 by a predetermined distance.
To receive the displacing action force. In addition, fixed electrodes 9a to
9c, 11a to 11c, 13a to 13c, 15a to 15
c is fixed to the upper surface of the substrate 1 and is arranged to face the movable electrodes 7a to 7c and 8a to 8c which are part of the beam structure 2.

In this type of sensor, the lower insulating thin films 18 a and 18 b and the conductive thin film 19
And a lower electrode 24 are formed by the conductive thin film 19, and a wiring pattern 22, 23, 25 and a lower electrode 24 are formed.
Opening 2 formed in upper-layer insulating thin film 20
9a to 29c, 31a to 31c, 30b to 30d, 32
a, fixed electrode 9a disposed on substrate 1 through 32b
-9c, 11a-11c, 13a-13c, 15a-1
5c, beam structure 2, electrode extraction part (electric connection member) 27a
~ 27d.

As described above, the insulating film is disposed on the upper surface of the substrate 1 and the thin film wiring or electrode is buried therein, and the buried thin film (polysilicon layer) is used as the wiring or electrode on the substrate side. An SOI substrate (embedded SOI substrate) is used. By using this structure, wiring or electrodes can be formed by insulator separation, and the electrode extraction portions 27a to 27d and the pad electrodes 34a to 34d are formed on the upper surface of the substrate 1.
34d can be arranged intensively at the end of the chip, and the flat portion 30, which is a flat region, can be easily formed between the electrode extraction portions 27a to 27d and the sensor element portion.

Further, a cap substrate (second substrate) 200 having a concave portion 202 as a protective cap is bonded to the flat portion 30 having a flat surface through the bonding film 201. No gap is generated at the joint portion with 30. Therefore, the cap substrate 2
When the sensor element portion including the movable portion is protected at 00, a semiconductor dynamic quantity sensor capable of easily ensuring the tightness inside the cap substrate 200 is provided.

In this manner, in the highly reliable semiconductor dynamic quantity sensor having the beam structure 2 formed of single-crystal silicon, the movable portion is covered with the cap substrate 200 to protect the movable portion. In addition, the periphery of the movable part is sealed with an inert gas or vacuum to protect the movable part from water pressure and water flow when dicing and cutting into chips from the wafer state, and into the movable part when molding the chip with resin. It is possible to prevent the resin from entering.

Further, by covering the sensor element portion with the cap substrate 200, it is possible to prevent malfunctions due to dust and the like during the process of the semiconductor dynamic quantity sensor and during operation.
In addition, since the inside of the cap substrate 200 can be gas-sealed or vacuum-sealed, a change with time during operation of the sensor can be minimized.

(B) A laminate 21 of lower insulating thin films 18 a and 18 b, a conductive thin film 19 and an upper insulating thin film 20 is disposed on the upper surface of the substrate 1. A wiring pattern 22 of the fixed electrode and a wiring pattern 23 of the second fixed electrode are formed, and the first and second wirings are formed through the openings 29a to 29c and 31a to 31c in the upper insulating thin film 20 and the anchor part of the fixed electrode. Fixed electrode wiring patterns 22 and 23 and first and second fixed electrodes 9a to 9
c, 11a to 11c, 13a to 13c, 15a to 15c
And were electrically connected.

In the portion where the wiring pattern 22 and the lower electrode 24 intersect, and in the portion where the wiring patterns 23 and 25 intersect, the opening formed in the upper insulating thin film 20 and the anchor One bridges the other by the bridge 26 formed by the portions (impurity-doped polysilicon) 26a and 26b.

As described above, the insulating film is disposed on the upper surface of the substrate 1, the thin wiring patterns 22 and 23 are embedded therein, and the first fixed electrode energizing line is formed by using the wiring patterns 22 and 23. And the second fixed electrode energizing line can be crossed, and the lower electrode 24 and the wiring pattern 25 for the movable electrode (for the beam structure) intersect with each of the fixed electrode energizing lines 22 and 23. Can be done.

(C) The lower electrode (fixed electrode for canceling electrostatic force) 24 is formed by the conductive thin film 19, and the opening (not shown) in the upper insulating thin film 20 and the anchor portion of the beam structure 2 are formed. The lower electrode 24 and the beam structure 2 were electrically connected through 3a and 3b. Thereby, the beam structure (movable part) 2 and the lower electrode 24 can be set at the same potential to cancel the electrostatic force generated between the beam structure 2 and the substrate 1, and between the beam structure 2 and the substrate 1. Can prevent the beam structure 2 from adhering to the substrate 1 due to a slight potential difference.

(D) Since single-crystal silicon, which is a brittle material having known physical properties such as Young's modulus, is used as the material of the beam structure 2, the reliability of the beam structure 2 can be increased. (E) By using a polysilicon thin film as the conductive thin film 19 and separating the periphery with an insulator thin film, it is possible to further reduce the influence of a leak current or the like in a high temperature region as in the case of pn junction isolation. (F) Since the servo mechanism (servo control) is adopted, the beam structure 2 by the action of acceleration is used.
Can be minimized, and the reliability of the sensor can be increased.

(Second Embodiment) In the second embodiment, the manufacturing method described in the first embodiment is applied to the first semiconductor substrate 4 for the completed embedded SOI substrates 40 and 48.
By removing the unnecessary region at 0, the pattern of the beam structure 2 is formed. On the other hand, before bonding the embedded SOI substrate, a groove is formed at a predetermined region of the first semiconductor substrate 40. The main difference is that the pattern of the beam structure 2 is formed.

FIGS. 14 to 18 are views showing the manufacturing process of the present embodiment.
FIG. 7 is a schematic cross-sectional view showing a manufacturing process using the cross section shown in FIG. 6). Hereinafter, in the present embodiment, differences from the manufacturing method of the first embodiment will be mainly described, and elements formed by the same manufacturing method as in the first embodiment include: The same reference numerals as those in FIGS. 8 to 13 denote the same parts, and a description thereof will be omitted.

First, as shown in FIG. 14A, a single crystal silicon substrate (first semiconductor substrate) 40 is subjected to trench etching to form a groove A (alignment mark and end point detection) similar to that of the first embodiment. A groove as a mark) is formed, and a groove pattern 60a for forming a beam structure is formed. That is, the groove 60a is formed in a predetermined region of the silicon substrate 40.

Thereafter, as shown in FIG. 14A, a silicon oxide film (a thin film for a sacrifice layer) 41 is formed on the silicon substrate 40 including the groove 60a, and a silicon nitride film (second film) is formed thereon. The first insulating thin film 43 is formed. Next, FIG.
As shown in FIG. 4B, openings 44a to 44g are formed in the anchor portion forming region in the stacked body of the silicon oxide film 41 and the silicon nitride film 43. Subsequently, the opening 44a
A polysilicon thin film (conductive thin film) 45 is formed on the silicon nitride film 43 including the conductive pattern 45a and the lower electrode 4 in a predetermined region on the silicon nitride film 43.
5b and the anchor part 45c are formed.

Further, as shown in FIGS. 15A and 15B, the silicon nitride film 4 including the upper portion of the polysilicon thin film 45 is formed.
3, a silicon nitride film 46 as a second insulator thin film
a, A silicon oxide film 46b is formed. Next, FIG.
As shown in (a), a polysilicon thin film (thin film for bonding) 47 is formed on the silicon oxide film 46b, and the surface thereof is flattened by mechanical polishing or the like. Next, as shown in FIG. 16B, the surface of the polysilicon thin film 47 is bonded to a silicon substrate (second semiconductor substrate) 48.

Further, as shown in FIG. 17A, the silicon substrates 40 and 48 are turned upside down, and the silicon substrate 40 side is subjected to mechanical polishing or the like to a desired thickness (for example, 10 to 20 μm).
m). By this polishing, the silicon substrate 4
The polished surface of 0 is a flat surface with no steps, and the flat portion 30 is formed. Next, as shown in FIG.
Formation of an interlayer insulating film 51, formation of a contact hole 52,
An aluminum electrode 53 is formed.

Thereafter, as shown in FIG. 18, the silicon oxide films 41 and 51 are removed by etching with an HF-based etchant, and the beam structure having the movable electrodes 8a to 8c is made movable. That is, the silicon oxide film 41 in a predetermined region is removed by sacrifice layer etching using an etchant, so that the silicon substrate 40 has a movable structure. Through the above steps, the servo control type acceleration sensor can be formed by using the embedded SOI substrate and forming the wiring pattern 45a and the lower electrode 45b by insulator separation.

In the present embodiment, in this step (the step of removing the silicon oxide film 41 in a predetermined area by the sacrifice layer etching using an etchant to make the silicon substrate 40 a movable structure), a thin film for the sacrifice layer is formed. Since the silicon oxide film is used and the polysilicon thin film is used as the conductive thin film, it is not necessary to control the end point by time control in the sacrificial layer etching step when releasing the beam structure, as in the first embodiment. It is possible to easily control the spring constant and the like.

Next, also in the present embodiment, a step of forming the concave portion 202 on one side of the cap substrate (third semiconductor substrate) 200, a step of forming the bonding film 201 on one side of the cap substrate 200, A step of bonding the cap substrate 200 via the bonding film 201 to the flat portions 30 of the combined silicon substrates 40 and 48 so as to cover the movable structure with the concave portions 202 (third semiconductor substrate bonding). Steps) are performed in the same manner as in the first embodiment to complete the semiconductor acceleration sensor.

Here, as in the first embodiment, the third semiconductor substrate bonding step is performed in an inert gas atmosphere or a vacuum in consideration of the enhancement of the detection sensitivity of the sensor and the stabilization of the characteristics. It is preferred to carry out at. Further, after forming the communication groove 205 in the cap substrate 200 and performing the third semiconductor substrate bonding step in the air, the inside of the cavity 204 may be filled with an inert gas or in a vacuum using the communication groove 205. good.

(Other Embodiments) In the above embodiment, the lower electrode 24 may not be provided. Further, the present invention is not limited to the above embodiments. For example, in the above embodiment, the acceleration is detected by using the electrostatic servo system. Although the detection is performed by applying such an electrostatic force), the sensor may be embodied as a sensor that directly detects displacement as a change in capacitance.

Further, the present invention relates to the above-mentioned JP-A-9-21.
The present invention is also applicable to a yaw rate sensor as described in JP-A-1022. This yaw rate sensor is composed of a substrate and a single crystal semiconductor material, is disposed at a predetermined interval on the upper surface of the substrate, has a first movable electrode on one side, and has a second movable electrode on the other side. A beam structure having a first excitation fixed electrode fixed to the upper surface of the substrate and opposed to the first movable electrode; and a second movable electrode fixed to the upper surface of the substrate. A second excitation fixed electrode disposed so as to face, and a mechanical quantity detection fixed electrode formed in a region opposed to at least a part of the beam structure on the upper surface of the substrate, Opposite phases exist between the first movable electrode of the beam structure and the first fixed electrode for excitation and between the second movable electrode of the beam structure and the second fixed electrode for excitation. While forcibly oscillating the beam structure by applying electrostatic force, A semiconductor dynamic quantity sensor to detect the physical quantity acting on the beam structure based on the capacitance of the capacitor formed between the beam structure and the dynamic quantity detecting fixed electrode.

Also, in this yaw rate sensor,
On the upper surface of the substrate, a laminate of a lower insulating thin film, a conductive thin film, and an upper insulating thin film is disposed, and the conductive thin film is used to form the fixed electrode for detecting a physical quantity, and a wiring pattern of the movable electrodes. And a wiring pattern for each of the fixed electrodes, and these wiring patterns may be electrically connected to an electrical connection member disposed on the substrate through an opening formed in the upper insulating thin film. Further, as in the above embodiment, the beam structure and the fixed electrode form a sensor element as a detection unit, and the sensor is provided between the electric connection member and the sensor element on the substrate. A flat portion having a flat surface without a step is formed so as to surround the element portion, the cap substrate is bonded to this flat portion, and the sensor element portion is covered and protected by a concave portion of the cap substrate. Good.

Further, the present invention can be embodied in a semiconductor dynamic quantity sensor for detecting a dynamic quantity such as vibration in addition to acceleration and yaw rate.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a central portion of FIG.

FIG. 3 is a sectional view taken along line AA in FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

FIG. 5 is a sectional view taken along line CC in FIG.

FIG. 6 is a sectional view taken along line DD in FIG.

FIG. 7 is a perspective view taken along the line AA in FIG. 1;

FIG. 8 is a process chart showing a method for manufacturing the semiconductor acceleration sensor according to the first embodiment of the present invention.

FIG. 9 is a process chart illustrating a manufacturing method following FIG. 8;

FIG. 10 is a process chart showing a manufacturing method following FIG. 9;

FIG. 11 is a process chart showing a manufacturing method continued from FIG. 10;

FIG. 12 is a process chart illustrating a manufacturing method following FIG. 11;

FIG. 13 is a process chart showing a manufacturing method continued from FIG. 12;

FIG. 14 is a process chart showing a method for manufacturing a semiconductor acceleration sensor according to the second embodiment of the present invention.

FIG. 15 is a process chart showing a manufacturing method continued from FIG. 14;

FIG. 16 is a process chart showing a manufacturing method following FIG. 15;

FIG. 17 is a process chart illustrating a manufacturing method following FIG. 16;

FIG. 18 is a process chart illustrating a manufacturing method following FIG. 17;

[Explanation of symbols]

2 ... beam structure, 7a-7c, 8a-8c ... movable electrode, 9
a to 9c, 13a to 13c ... first fixed electrodes, 10a to
10c, 12a to 12c, 14a to 14c, 16a to 1
6c anchor part, 11a-11c, 15a-15c ...
Second fixed electrode 17, silicon substrate (first substrate),
18a, 18b: lower insulating thin film, 19: conductive thin film, 20: upper insulating thin film, 21: laminated body, 22, 2
3, 25: wiring pattern, 24: lower electrode, 27a to 2
7d: electrode extraction portion (electric connection member), 30: flat portion, 4
0: silicon substrate (first semiconductor substrate), 41: silicon oxide film (thin film for sacrificial layer), 43: silicon nitride film (first insulator thin film), 44a to 44g: openings, 45: polysilicon thin film (Conductive thin film), 46a: silicon nitride film (second insulating thin film), 46b: silicon oxide film (second insulating thin film), 47: polysilicon thin film (thin film for bonding), 48: silicon substrate (Second semiconductor substrate), 60
a: groove pattern for forming a beam structure, 200: cap substrate (second substrate), 201: bonding film, 202
... recess, 205 ... communication groove.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Nobuyuki Kato 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 4M112 AA02 BA07 CA24 CA26 CA34 DA04 DA05 DA18 EA03 EA04 EA06 EA07

Claims (13)

[Claims] 1. A beam structure comprising a first substrate (17) and a single crystal semiconductor material, the beam structure being disposed at a predetermined interval on an upper surface of the first substrate, and receiving an acting force displaced by a mechanical quantity. And a fixed electrode (9a-9) fixed to the upper surface of the first substrate and arranged to face at least a part of the beam structure.
c, 11a to 11c, 13a to 13c, 15a to 15
c) on the upper surface of the first substrate, a lower insulating thin film (18a,
18b), the conductive thin film (19), and the upper insulating thin film (2)
0), a wiring (22, 23, 25) or an electrode (24) was formed by the conductive thin film, and the wiring or the electrode was formed on the upper insulating thin film. In a semiconductor physical quantity sensor electrically connected to electric connection members (27a to 27d) disposed on the first substrate through an opening, a sensor element as a detection unit is formed by the beam structure and the fixed electrode. A flat portion (3) having a flat surface without a step between the electric connection member and the sensor element portion on the first substrate so as to surround the sensor element portion.
0) is formed, and the one surface side of the second substrate (200) having the concave portion (202) on one surface side with respect to this flat portion is the bonding film (20).
1) a semiconductor physical quantity sensor, wherein the sensor element portion is bonded via the first substrate, and the sensor element portion is covered and protected by the concave portion of the second substrate. 2. The conductive thin film (19) has a protruding portion (10a to 10a) protruding to an upper side of the upper insulating thin film through an opening formed in the upper insulating thin film (20).
10c, 12a to 12c, 14a to 14c, 16a to 1
6c), and the fixed electrodes (9a to 9c, 11a)
2. The semiconductor dynamic quantity sensor according to claim 1, wherein the conductive thin films are connected to the conductive thin film. 11. 3. A movable electrode (7a to 7c, comprising a first substrate (17) and a single crystal semiconductor material, which is arranged at a predetermined distance on the upper surface of the first substrate and extends in parallel with each other. A first fixed electrode (9a to 9c) fixed to the upper surface of the first substrate and disposed opposite to one side surface of each of the movable electrodes, , 13a to 13c) and second fixed electrodes (11a to 11c, 15a to 15c) fixed to the upper surface of the first substrate and arranged opposite to the other side surfaces of the movable electrodes, respectively. A first capacitor is formed by the movable electrode of the beam structure and the first fixed electrode, and a second capacitor is formed by the movable electrode of the beam structure and the second fixed electrode. The first substrate On the upper surface, the lower insulating thin film (18
a, 18b), a conductive thin film (19), and an upper insulating thin film (20), and a laminated body (21) is arranged. The movable thin film, the first fixed electrode, and the second
Electrical connection members (27b), which are formed on the first substrate through the openings formed in the upper insulating thin film, by forming respective wiring patterns (22, 23, 25) of the fixed electrode of , 27c, 27d) electrically connected to the first and second substrates, wherein the beam structure and the fixed electrode form a sensor element as a detection unit, A flat portion (3) having a flat surface without a step between the electrical connection member and the sensor element portion so as to surround the sensor element portion.
0) is formed, and the one surface side of the second substrate (200) having the concave portion (202) on one surface side with respect to this flat portion is the bonding film (20).
1) a semiconductor physical quantity sensor, wherein the sensor element portion is bonded via the first substrate, and the sensor element portion is covered and protected by the concave portion of the second substrate. 4. The semiconductor dynamic quantity according to claim 1, wherein the flat portion (30) is formed above the upper insulating thin film (20). Sensor. 5. The material forming the flat portion (30) is as follows:
The semiconductor dynamic quantity sensor according to claim 4, wherein the same material as the material forming the beam structure (2) is used. 6. The semiconductor dynamic quantity sensor according to claim 1, wherein the beam structure (2) is made of single crystal silicon. 7. The semiconductor device according to claim 1, wherein a polysilicon thin film is used as said conductive thin film.
Semiconductor dynamic quantity sensor according to any one of the above. 8. A space between the sensor element and the recess (202) of the second substrate (200) is filled with an inert gas or is in a vacuum state. Item 8. A semiconductor dynamic quantity sensor according to any one of Items 1 to 7. 9. A first step of stacking a sacrificial layer thin film (41) and a first insulator thin film (43) on a first semiconductor substrate (40); A second step of opening an anchor portion forming region in the laminate with the insulating thin film; and forming a conductive thin film (45) in a predetermined region on the first insulating thin film including the openings (44a to 44g). Third
A step of forming a second insulating thin film (46a, 46b) on the first insulating thin film including on the conductive thin film; and bonding the second insulating thin film on the second insulating thin film. Forming a thin film for bonding (47) and flattening the surface of the thin film for bonding.
A step of bonding the surface of the thin film for bonding to a second semiconductor substrate (48); and polishing the first semiconductor substrate to a desired thickness and the first semiconductor. A seventh step of forming a flat portion (30) on the surface of the substrate; an eighth step of removing unnecessary regions in the first semiconductor substrate to obtain a desired shape; and etching of a predetermined region by etching using an etchant. A ninth step of removing the thin film for the sacrificial layer to make the first semiconductor substrate a movable structure; and a concave portion (202) on one surface side of the third semiconductor substrate (200).
A tenth step of forming a bonding film (201) on one surface side of the third semiconductor substrate; and a tenth step of forming a bonding film (201) on the one side of the third semiconductor substrate. A twelfth step of bonding the third semiconductor substrate via the bonding film so as to cover the movable structure portion with the concave portion. Method. 10. A first step of forming a groove (60a) in a predetermined region of a first semiconductor substrate (40); and forming a thin film for a sacrificial layer (41) on the first semiconductor substrate including the groove. A second step of laminating a first insulator thin film (43); a third step of opening an anchor portion forming region in a laminate of the sacrificial layer thin film and the first insulator thin film; (4) forming a conductive thin film (45) in a predetermined region on the first insulating thin film including (44a to 44g);
A step of forming a second insulating thin film (46a, 46b) on the first insulating thin film including on the conductive thin film; and bonding the second insulating thin film on the second insulating thin film. Forming a thin film for bonding (47) and flattening the surface of the thin film for bonding.
A step of bonding the surface of the bonding thin film to a second semiconductor substrate (48); and polishing the first semiconductor substrate to a desired thickness and the first semiconductor. An eighth step of forming a flat portion (30) on the surface of the substrate, and a ninth step of removing the sacrificial layer thin film in a predetermined region by etching using an etchant to make the first semiconductor substrate a movable structure. A concave portion (202) on one surface side of the third semiconductor substrate (200);
A tenth step of forming a bonding film (201) on one surface side of the third semiconductor substrate; and a tenth step of forming a bonding film (201) on the one side of the third semiconductor substrate. A twelfth step of bonding the third semiconductor substrate via the bonding film so as to cover the movable structure portion with the concave portion. Method. 11. The method according to claim 9, wherein the twelfth step is performed in an inert gas atmosphere or in a vacuum. 12. Performing the third step before performing the twelfth step.
Forming a communication groove (205) for communicating between the inside and the outside of the concave portion (202) with the semiconductor substrate (200), and after performing the twelfth step, the concave portion via the communication groove; The method according to claim 9, wherein an inert gas is filled in the inside of the semiconductor device, and subsequently, the communication groove is sealed. 13. Performing the third step before performing the twelfth step.
Forming a communication groove (205) for communicating between the inside and the outside of the concave portion (202) with the semiconductor substrate (200), and after performing the twelfth step, the concave portion via the communication groove; The method according to claim 9, wherein the inside of the sensor is evacuated to a vacuum, and then the communication groove is sealed.