JP3512026B2 - Semiconductor dynamic quantity sensor and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor dynamical quantity sensor having a movable part having a beam structure, for example, acceleration,
The present invention relates to a semiconductor mechanical quantity sensor for detecting a mechanical quantity such as yaw rate and vibration, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, the basic principle of a mechanical quantity sensor such as an acceleration sensor is to measure displacement or force when a mechanical quantity acts on a mass part (mass part) connected to a beam using a beam called a flexural beam. It is to be.

In recent years, there has been an increasing demand for miniaturization and cost reduction of mechanical quantity sensors such as acceleration sensors used for automobile suspension control and airbags. For this reason,
Japanese Examined Patent Publication No. 6-44008 discloses a differential capacitance type semiconductor acceleration sensor using polysilicon as a beam structure having electrodes. This type of sensor is shown in FIGS.
An explanation will be given using 5, 36. A plan view of the sensor is shown in FIG. 34, and FIG. 35 shows XXXV-XX in FIG.
A cross-sectional view taken along line XV is shown in FIG.
XXVI sectional drawing is shown.

A beam 132 extends from the anchor portion 131 on the silicon substrate 130, and a mass 1 is attached to the beam 132.
33 is supported, and the movable electrode 13
4 is projected. On the other hand, on the silicon substrate 130, two fixed electrodes 135 are provided for one movable electrode 134.
a and 135b are arranged so as to face each other. An electrostatic capacitance is formed by the movable electrode 134 and the fixed electrodes 135a and 135b to perform a servo operation. Anchor part 131
The beam 132, the mass 133, and the movable electrode 134 are made of polysilicon, and the mass 133 and the movable electrode 13 are formed.
4 is disposed at a predetermined distance from the silicon substrate 130. Further, the fixed electrodes 135a and 135b are fixed to the substrate 130 at the anchor portions 136 at the ends. These are formed on the silicon substrate 130 using the surface micromachining technique.

The detection principle will be described with reference to FIG. The movable electrode 134 is located at the center of the fixed electrodes 135a and 135b on both sides, and the movable electrode 134 and the fixed electrodes 135a and 135b.
The electrostatic capacitances C1 and C2 between them are equal. In addition, the movable electrode 134
Voltages V1 and V2 are applied between the fixed electrodes 135a and 135b and V1 = V2 when acceleration is not generated.
V2, and the movable electrode 134 is the fixed electrodes 135a and 13a.
It is pulled from 5b with the same electrostatic force. Here, when the acceleration acts in a direction parallel to the substrate surface and the movable electrode 134 is displaced, the movable electrode 134 and the fixed electrodes 135a, 135
The distance to b changes and the electrostatic capacitances C1 and C2 become unequal. If, for example, the movable electrode 134 is displaced toward the fixed electrode 135a side so that the electrostatic capacities become equal at this time, the voltage V1 decreases and the voltage V2 increases. As a result, the movable electrode 134 is pulled toward the fixed electrode 135b by the electrostatic force. The movable electrode 134 becomes the center position and the electrostatic capacitance C
If 1 and C2 are equal, the acceleration and the electrostatic force are evenly balanced, and the magnitude of acceleration can be obtained from the voltages V1 and V2 at this time.

The manufacturing is performed in the steps shown in FIGS. As shown in FIG. 37, a sacrifice layer (silicon oxide film) 138 is deposited on a silicon substrate 137 and an opening 139 is provided in a predetermined region. And this opening 139
A polysilicon thin film 140 is deposited on the sacrificial layer 138 including, and the polysilicon thin film 140 is patterned into a predetermined shape. Further, as shown in FIG. 38, the sacrificial layer 138 is removed by etching to form the air gap 141 to form a beam structure made of the polysilicon thin film 140.

In the acceleration sensor disclosed in Japanese Patent Publication No. 6-44008, a polycrystalline silicon thin film is used as a material for the beam structure. However, the mechanical properties of such polycrystalline silicon are unknown, and there is a problem in that the mechanical reliability is lower than that of single crystal silicon. Further, there is a problem of warping of the beam structure due to internal stress and stress distribution generated when forming polycrystalline silicon on the silicon oxide film on the single crystal silicon substrate. Due to these problems, it is difficult to create a beam structure and the spring constant of the sensor changes.

On the other hand, SOI (Silicon)
on Insulator substrate and single crystal silicon is used as the beam structure, thereby improving the mechanical reliability. This type of sensor is shown in FIGS.
This will be described using 0 and 41. FIG. 39 shows a plan view of the sensor, and FIG. 40 shows the XXX-XX-XX in FIG.
41 is a sectional view taken along line XX, and FIG. 41 shows XXXXI-X in FIG.
XXXI sectional drawing is shown.

In this acceleration sensor, the vibrating mass body 147 is joined to the fixed support body 146 by the flexible beam 145, and the vibrating mass body 147 can be moved. The vibrating mass 147 is made of phosphorus-doped single crystal silicon. The fixed support 146 is fixed on the substrate 148 in an electrically insulated state. Vibration mass 14
7 includes movable electrodes 149 extending in directions parallel to each other. The beam structure 150 is constituted by these members 145, 146, 147, 149. Also, the movable electrode 1
Fixed electrodes 151 and 152 are arranged so as to face 49, and an electrostatic capacitance is formed between the movable electrode 149 and the fixed electrodes 151 and 152. Then, the beam 145 is applied to the substrate 1
When the movable electrode 149 is displaced in the direction parallel to the surface of 48 (Y-axis direction in FIG. 39), the electrostatic capacitance is changed.

Next, a method of manufacturing this acceleration sensor will be described with reference to FIGS. First, as shown in FIG. 42, in order to form a SIMOX layer on a substrate 148,
Oxygen ion (O ⁺ or O ₂ ⁺ ) single crystal silicon substrate 1
48 to 10 ¹⁶ to 1 at 100 keV to 1000 keV
0 ¹⁸ dose / cm ² injection, 1150 ° C-1400 ° C
Heat treatment. As a result, the thickness of the silicon oxide film layer 153 is about 400 nm and the thickness of the surface silicon layer 154 is 1
An SOI substrate of about 50 nm is formed. After that, FIG.
As shown in FIG. 3, the silicon layer 154 and a part of the silicon oxide film layer 153 are etched through photolithography. Further, as shown in FIG. 44, the single crystal silicon layer 155 is epitaxially grown to a thickness of 1 μm to 100 μm.
(Normally 10 to 20 μm) is formed. Next, as shown in FIG. 45, after forming an electrode 156 made of metal for connection with the measurement circuit, a predetermined electrode shape is formed through photolithography. Further, as shown in FIG. 46, reactive vapor dry etching or the like is performed on the silicon layer 155 to form the fixed electrodes 151 and 152, the movable electrode 149 and the like. Finally, the oxide film layer 153 is removed by liquid phase etching using HF or the like to make the beam structure movable.

[0011]

However, in this etching step, the movable electrode 149 that is a beam structure is used.
There is a problem that the etching liquid remains between the substrate and the substrate 148 and the two are fixed.

Therefore, an object of the present invention is to provide a semiconductor dynamic quantity sensor in which a beam structure is formed on a substrate, which can prevent the beam structure and the substrate from being fixed to each other when the beam structure is formed. It is to provide a mechanical quantity sensor.

[0013]

According to a first aspect of the present invention, there is provided a beam, which is made of a semiconductor material and a substrate, is arranged at a predetermined distance on the upper surface of the substrate, and receives an acting force that is displaced by a mechanical amount. Fixed to the structure and the top surface of the substrate,
A semiconductor dynamical quantity sensor comprising a fixed electrode arranged to face at least a part of the beam structure, which is an upper surface part of the substrate and corresponds to a lower part of the beam structure, A lower electrode electrically connected to the beam structure is arranged.
And a protrusion is formed on the surface of the lower electrode on the beam structure side .

By forming the projections on the lower portion of the beam structure in this way, the adhesion area between the beam structure and the substrate is reduced during the formation of the beam structure, and the adhesion between the two can be prevented.

The invention according to claim 2 is characterized in that the beam structure is made of single crystal silicon. Thus, the reliability of the beam structure can be increased by using the single crystal silicon, which is a brittle material with known physical properties such as Young's modulus, as the material of the beam structure.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. In this embodiment, it is applied to a semiconductor acceleration sensor. More specifically, it is applied to a servo-controlled differential capacitance type semiconductor dynamic quantity sensor.

FIG. 1 is a plan view of a semiconductor acceleration sensor according to this embodiment, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG.
Is a IV-IV sectional view in FIG. 1, and FIG. 5 is a VV sectional view in FIG.

In FIGS. 1 and 2, the upper surface of the substrate 1 is
A beam structure 2 made of single crystal silicon (single crystal semiconductor material) is arranged. The beam structure 2 is erected by four anchor portions 3a, 3b, 3c, 3d projecting from the substrate 1 side, and is arranged on the upper surface of the substrate 1 at predetermined intervals. Anchor portions 3a, 3b, 3c,
3d is made of a polysilicon thin film. The beam portion 4 is installed between the anchor portion 3a and the anchor portion 3b, and the beam portion 5 is installed between the anchor portion 3c and the anchor portion 3d. 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 in the vertical direction, and the through hole 6a facilitates the penetration of the etching solution during the sacrifice layer etching. Furthermore, from one side surface (the left side surface in FIG. 1) of the mass portion 6, the four movable electrodes 7a, 7b, 7c,
7d is protruding. The movable electrodes 7a, 7b, 7c,
7d has a rod shape and extends in parallel at equal intervals.
Further, four movable electrodes 8a, 8b, 8c, 8d project from the other side surface (right side surface in FIG. 1) of the mass portion 6. The movable electrodes 8a, 8b, 8c, 8d are rod-shaped and extend in parallel at equal intervals. here,
Beam parts 4, 5, mass part 6, movable electrodes 7a to 7d, 8a to 8
d is made movable by removing a part of the sacrificial layer oxide film 37 by etching. This etching region is indicated by Z1 in FIG.

As described above, the beam structure 2 has two comb-teeth-shaped movable electrodes. Four first fixed electrodes 9a, 9b, 9c and 9d are fixed on the upper surface of the substrate 1, and the fixed electrodes 9a to 9d are made of single crystal silicon. The first fixed electrodes 9a-9d are supported by anchor portions 10a, 10b, 10c, 10d protruding from the substrate 1 side, and are attached to one side surface of each movable electrode (bar-shaped portion) 7a-7d of the beam structure 2. It is arranged facing each other. In addition, the upper surface of the substrate 1 has four second fixed electrodes 11a, 11b, 11c, 1
1d is fixed, and the fixed electrodes 11a to 11d are made of single crystal silicon. The second fixed electrodes 11a to 11d are anchor portions 12a, 12b, 12 protruding from the substrate 1 side.
It is supported by c and 12d, and is arranged so as to face the other side surface of each movable electrode (bar-shaped portion) 7a to 7d of the beam structure 2.

Similarly, the first fixed electrodes 13a, 13b, 13c, 13d and the second fixed electrodes 15a, 15b, 15c, 15d are fixed on the upper surface of the substrate 1, and the fixed electrodes 13a to 13d and 15a to are fixed. 15d is made of single crystal silicon. The first fixed electrodes 13a to 13d are supported by the anchor portions 14a, 14b, 14c and 14d,
Further, the movable electrodes (bar-shaped portions) 8a to 8d of the beam structure 2 are arranged so as to face one side surface of each of the movable electrodes 8a to 8d. Also, the second fixed electrodes 15a to 15d are anchor portions 16a, 16b, 16
It is supported by c and 16d, and is arranged to face the other side surface of each movable electrode (bar-shaped portion) 8a to 8d of the beam structure 2.

As shown in FIG. 2, the substrate 1 comprises a silicon substrate (semiconductor substrate) 17 and a lower insulating thin film 1 formed on the silicon substrate (semiconductor substrate) 17.
8 and the conductive thin film 19 and the upper insulating thin film 20 are laminated. That is, the laminated body 21 of the lower-layer-side insulator thin film 18, the conductive thin film 19, and the upper-layer-side insulator thin film 20 is arranged on the upper surface of the silicon substrate 17, and the conductive thin film 19 is the insulator thin film. It is configured to be embedded in the inside of 18, 20. Lower layer insulator thin film 18
Is made of a silicon oxide film, the upper insulating thin film 20 is made of a silicon nitride film, and is formed by a CVD method or the like. The conductive thin film 19 is made of a polysilicon thin film doped with impurities such as phosphorus.

The conductive thin film 19 forms the four wiring patterns 22, 23, 24, 25 shown in FIG. 1 and the lower electrode (fixed electrode for canceling electrostatic force) 26. The wiring pattern 22 includes the first fixed electrode 9a,
The wirings 9b, 9c, and 9d are strip-shaped as shown in FIG. 1 and extend in an L-shape. The wiring pattern 23 is the second fixed electrode 11a, 11b, 11c, 11d.
Is a wiring pattern of, and has a strip shape as shown in FIG.
Moreover, it is extended in the L shape. Similarly, the wiring pattern 24 includes the first fixed electrodes 13a, 13b, 13c and 13d.
Wiring, and the wiring pattern 25 is the second fixed electrode 15
The wirings a, 15b, 15c, and 15d have a strip shape as shown in FIG. 1 and extend in an L shape. The lower electrode 26 is formed on the upper surface of the substrate 1 in a region facing the beam structure 2.

The movable electrode (bar-shaped portion) of the beam structure 2
A first capacitor is provided between 7a to 7d and the first fixed electrodes 9a to 9d, and a movable electrode (rod portion) 7 of the beam structure 2 is provided.
a-7d and the second fixed electrode 11a-11d between the second
Capacitor is formed. Similarly, the movable electrodes (bar-shaped portions) 8a to 8d of the beam structure 2 and the first fixed electrodes 13a to 1
3d, the first capacitor, the movable electrodes (rod portions) 8a to 8d of the beam structure 2 and the second fixed electrode 15a to.
A second capacitor is formed with 15d.

On the upper surface of the substrate 1, electrode lead-out portions 27a, 27b, 27c and 27d made of single crystal silicon are formed, and the electrode lead-out portions 27a, 27b, 27c and 27d are anchor portions 28a protruding from the substrate 1. , 28b, 28
It is supported by c and 28d.

As shown in FIG. 3, the upper insulator thin film 20 is formed.
Openings 29a, 29b, 29c, 29d and 30
And the anchor portion (impurity-doped polysilicon) 1 is formed in the openings 29a, 29b, 29c, 29d.
0a to 10d are arranged. An anchor portion (impurity-doped polysilicon) 28a is arranged in the opening 30. Therefore, the openings 29a to 29d and the anchor portions (impurity-doped polysilicon) 10a to 10d.
d through the wiring pattern 22 and the first fixed electrodes 9a-9
The wiring pattern 22 and the electrode lead-out portion 27a are electrically connected through the opening 30 and the anchor portion (impurity-doped polysilicon) 28a.

As shown in FIG. 4, the upper insulator thin film 20 is formed.
Openings 31a, 31b, 31c, 31d, 32 are formed in the. The above-mentioned anchor portions (impurity-doped polysilicon) 12a to 12d are provided in the openings 31a to 31d.
However, the aforementioned anchor portion 28c is arranged in the opening 32. Therefore, the openings 31a to 31d and the anchor portions (impurity-doped polysilicon) 12a to 12d.
Through the wiring pattern 23 and the second fixed electrodes 11a to 1
1d is electrically connected, and the wiring pattern 23 and the electrode lead-out portion 27c are electrically connected through the opening 32 and the anchor portion (impurity-doped polysilicon) 28c.

Similarly, the wiring pattern 24 of the first fixed electrode and the first fixed electrode 13a through the opening (not shown) in the upper insulating thin film 20 and the anchor portions 14a through 14d of the first fixed electrode. 13d is electrically connected, and the wiring pattern 24 and the electrode lead-out part 27b are electrically connected through the anchor part 28b.
Further, the wiring pattern 25 of the second fixed electrode and the second fixed electrodes 15a to 15d are electrically connected through the opening (not shown) in the upper insulating thin film 20 and the anchor portions 16a to 16d of the second fixed electrode. The wiring pattern 25 and the electrode lead-out portion 27d are electrically connected to each other through the anchor portion 28d.

Further, as shown in FIG. 2, an opening 33 is formed in the upper insulating thin film 20, and the anchor portions (impurity-doped polysilicon) 3a to 3d are formed in the opening 33.
Are arranged. Therefore, the anchor portion 3a of the beam structure
The lower electrode 26 and the beam structure 2 are electrically connected to each other through ~ 3d.

In this way, the substrate 1 has the wiring patterns 22 to 25 made of polysilicon and the lower electrode 26 as SO.
The structure is embedded under the I layer, and this structure is
It is formed using a surface micromachining technique.

On the other hand, as shown in FIGS. 1 and 2, an electrode (bonding pad) 34 made of an aluminum thin film is provided above the anchor portion 3a of the silicon substrate (semiconductor substrate) 17. Further, as shown in FIGS. 1, 3 and 4, electrodes (bonding pads) 35a, 35 made of an aluminum thin film are formed on the upper surfaces of the electrode lead-out portions 27a, 27b, 27c, 27d.
b, 35c and 35d are provided respectively. An interlayer insulating film 38 and a silicon nitride film 36 are formed on the upper surfaces of the electrode extraction portions 27a to 27d. This membrane 38,3
6 is formed in a region other than Z1 in FIG.

The movable electrodes 7a to 7d of the beam structure 2 are
Of the first capacitor formed between the first fixed electrode 9a-9d and the first fixed electrode 9a-9d (and the capacitance of the first capacitor formed between the movable electrode 8a-8d and the first fixed electrode 13a-13d). Capacity) and the movable electrode 7a of the beam structure 2
7d and the capacitance of the second capacitor formed between the second fixed electrodes 11a to 11d (and the movable electrodes 8a to 8d).
The acceleration acting on the beam structure 2 can be detected based on the capacitance of the second capacitor formed between the second fixed electrodes 15a to 15d. More specifically, the movable electrode and the fixed electrode form two differential capacitances, and the servo operation is performed so that the two capacitances become equal.

Further, by setting the beam structure 2 and the lower electrode 26 to an equal potential, the electrostatic force generated between the beam structure 2 and the substrate 1 is offset. That is, the lower electrode 26 is electrically equipotential because it is coupled to the beam portions 4 and 5 and the mass portion 6 through the anchor portions 3a to 3d, and the beam portions 4 and 5 and the mass portion 6 are electrostatically attracted to the substrate 1. Can be prevented from adhering to. That is, since the beam structure 2 is insulated from the silicon substrate 17, the beam structure 2 tends to adhere to the substrate 17 side even if the potential difference between the beam structure 2 and the silicon substrate 17 is small. Can be prevented.

By using the wiring patterns 22 to 25 and the lower electrode 26 separated from each other as described above, the aluminum electrodes (bonding pads) 34 and 35a to 35d can be taken out from the substrate surface, and the acceleration sensor is manufactured. The process can be facilitated.

Next, the detection principle of this acceleration sensor is shown in FIG.
Will be explained. Movable electrodes 7a-7d (8a-8d)
Are fixed electrodes 9a to 9d (13a to 13d) and 11 on both sides.
It is located at the center of a to 11d (15a to 15d), and the electrostatic capacitances C1 and C2 between the movable electrode and the fixed electrode are equal. Also, the movable electrodes 7a to 7d (8a to 8d) and the fixed electrodes 9a to 9d.
The voltage V1 is generated between the movable electrodes 7a to (13a to 13d).
7d (8a-8d) and fixed electrodes 11a-11d (15a
The voltage V2 is applied between ˜15d). And
When no acceleration is generated, V1 = V2, and the movable electrodes 7a to 7d (8a to 8d) are fixed electrodes 9a to 9d.
(13a to 13d) and 11a to 11d (15a to 15)
It is drawn from d) with equal electrostatic force. Here, the acceleration acts in a direction parallel to the substrate surface, and the movable electrodes 7a to 7a
When d (8a to 8d) is displaced, the distance between the movable electrode and the fixed electrode is changed and the electrostatic capacitances C1 and C2 are not equal. At this time, for example, the movable electrodes 7a to 7d (8a to 8d) are fixed electrodes 9a to 9d so that the electrostatic forces become equal.
If it is displaced to the (13a to 13d) side, the voltage V1 decreases and the voltage V2 increases. As a result, the movable electrode 7 is moved toward the fixed electrodes 11a to 11d (15a to 15d) by electrostatic force.
a to 7d (8a to 8d) are drawn. Movable electrodes 7a-7
d (8a to 8d) returns to the center position and electrostatic capacitances C1 and C2
Is equal, the acceleration and the electrostatic force are evenly balanced, and the magnitude of the acceleration can be obtained from the voltages V1 and V2 at this time.

As described above, in the first capacitor and the second capacitor, with respect to the displacement caused by the action of the mechanical quantity,
The voltage of the fixed electrode forming the first and second capacitors is controlled so that the movable electrode is not displaced, and the acceleration is detected by the change in the voltage.

Next, the manufacturing process of this acceleration sensor is shown in FIG.
This will be described with reference to .about.16. 6 to 16 are schematic cross-sectional views showing the manufacturing process on the AA cross section in FIG.
First, as shown in FIG. 6, a single crystal silicon substrate 40 as a first semiconductor substrate is prepared, and a silicon oxide film 41 as a sacrificial layer thin film is thermally oxidized on the silicon substrate 40 by CV.
A film is formed by the D method or the like. Then, as shown in FIG. 7, the silicon oxide film 41 is partially etched through photolithography to form a recess 42. Further, a silicon nitride film (first insulator thin film) 4 which serves as an etching stopper during the sacrifice layer etching in order to increase the surface irregularities.
3 is deposited. After that, openings 44a, 44b, and 44c are formed in the anchor portion formation region by dry etching or the like on the stacked body of the silicon oxide film 41 and the silicon nitride film 43 by photolithography. This opening 44
a to 44c are for connecting the beam structure and the substrate (lower electrode), and for connecting the fixed electrode (and electrode extraction portion) and the wiring pattern.

Subsequently, as shown in FIG.
A polysilicon thin film 45 to be a conductive thin film is formed on the silicon nitride film 43 containing a to 44c, and then impurities are introduced by phosphorus diffusion or the like, and wiring is performed in a predetermined region on the silicon nitride film 43 through photolithography. The pattern 45a, the lower electrode 45b, and the anchor portion 45c are formed. Further, as shown in FIG. 9, a silicon oxide film 46 as a second insulator thin film is formed on the silicon nitride film 43 including the polysilicon thin film (45) by the CVD method or the like.

Further, as shown in FIG. 10, a polysilicon thin film 4 as a bonding thin film is formed on the silicon oxide film 46.
7 is formed, and the surface is planarized by mechanical polishing or the like for bonding to the polysilicon thin film 47.

Then, as shown in FIG. 11, a single crystal silicon substrate (supporting substrate) 48 different from the silicon substrate 40 is prepared, and the surface of the polysilicon thin film 47 and the silicon substrate 48 as the second semiconductor substrate are prepared. Stick together.

Further, as shown in FIG. 12, the silicon substrates 40 and 48 are turned upside down, and the silicon substrate 40 side is mechanically polished or the like to be thinned to a desired thickness (for example, 1 to 2 μm). After that, a groove is formed in the silicon substrate 40 with a constant width by trench etching using a photolithography technique, and thereafter, a groove pattern 49 for forming a beam structure is formed. In this way, the silicon substrate 4
The unwanted area (49) at 0 is removed to give the desired shape. Further, here, impurities are introduced into the silicon substrate 40 by phosphorus diffusion or the like so as to serve as electrodes for later detecting the electrostatic capacitance.

In this step (step of removing an unnecessary region in the silicon substrate 40 to obtain a desired shape), the silicon substrate 40 is thin (for example, 1 to 2 μm) so as to satisfy the lower pattern resolution of the stepper. The shape of the openings (44a to 44c in FIG. 7) of the silicon oxide film 41 under the silicon substrate 40 can be seen through, and photomask alignment can be performed accurately.

After that, as shown in FIG. 13, a silicon oxide film 50 is formed by the CVD method or the like, and is etched back by dry etching or the like to flatten the substrate surface. Further, as shown in FIG. 14, an interlayer insulating film 51 is formed,
A contact hole 52 is formed by dry etching or the like through photolithography. And the interlayer insulating film 5
A silicon nitride film 76 is formed in a predetermined region above 1.

Further, as shown in FIG. 15, an aluminum electrode 53 is formed by film formation / photolithography, and then a passivation film 54 is formed by film formation / photolithography.

Finally, as shown in FIG. 16, the silicon oxide films 41 and 50 are removed by etching with an HF-based etching solution to make the beam structure 56 having the movable electrode portion 55 and the like movable. That is, the silicon oxide film 41 in a predetermined region is removed by sacrifice layer etching using an etching solution to make the silicon substrate 40 a movable structure. At this time, in order to prevent the movable part from sticking to the substrate during the drying process after etching, a sublimation agent such as valadichlorobenzene is used.

In this step (the step of removing the silicon oxide film 41 in a predetermined region by etching the sacrificial layer using an etching solution to make the silicon substrate 40 a movable structure),
The anchor portion 45c in the movable portion is made of a conductive thin film (polysilicon), and etching stops at the anchor portion 45c, so that there is no variation. That is, in the present 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 etching solution is used, the silicon oxide film is melted in HF but the polysilicon thin film is not melted. Therefore, it is not necessary to accurately control the concentration and temperature of the HF-based etching solution or to finish the etching with precise time control, which facilitates manufacturing.

That is, when the sacrifice layer is etched, FIG.
When the SOI substrate shown in FIG. 2 is used, the length of the beam changes depending on the etching time. However, in the present embodiment, the etching is selectively finished when the anchor portion is etched regardless of the etching time.
The length of the beam is always constant.

Since the anchor portion can be formed in this manner, it is not necessary to control the end point by controlling the time in the sacrifice layer etching step when releasing the beam structure, and it is possible to easily control the spring constant and the like. Becomes

In the sacrifice layer etching step,
Since the projections 57 shown in FIG. 16 are formed by the recesses 42 shown in FIG. 7, a rinse liquid (such as pure water) between the liquid movable part and the substrate (in the step of replacing the etching liquid after the beam structure is released). Although a droplet of the replacement liquid remains, the adhesion area of the droplet is reduced and the surface tension of the droplet is reduced to prevent the movable part from sticking to the substrate during evaporation of the rinse liquid.

In this way, by using the embedded SOI substrate, the wiring pattern 45a and the lower electrode 45b are formed by insulating material isolation, and a servo control type acceleration sensor can be formed.

As described above, this embodiment has the following characteristics (b) to (f).

(A) The beam structures 2 are arranged at predetermined intervals on the upper surface of the substrate 1, and the acceleration (mechanical amount)
Receives an acting force that is displaced by. In addition, fixed electrodes 9a-9
d, 11a to 11d, 13a to 13d, 15a to 15d
Is fixed to the upper surface of the substrate 1 and is arranged so as to face the movable electrodes 7a to 7d and 8a to 8d which are a part of the beam structure 2. In this type of sensor, on the upper surface of the substrate 1,
A laminated body 21 of the lower layer side insulator thin film 18, the conductive thin film 19 and the upper side insulator thin film 20 shown in FIG. 2 is arranged, and the conductive thin film 19 forms wirings 22 to 25 and electrodes 26. ˜25 and the electrode 26 are formed in the upper insulator thin film 20 with openings 29a to 29d, 31a to 31d, 3
Fixed electrodes 9a to 9d, 11a to 11d, 13a to 13d, 15a arranged on the substrate 1 through 0, 32 and 33.
.About.15d, the beam structure 2, and the electrode lead-out portions 27a to 27d (electrical connection members) were electrically connected. In this way, the insulating film is arranged on the upper surface of the substrate 1, the thin film wiring or the electrode is embedded therein, and the SOI substrate using the embedded thin film (polysilicon layer) as the wiring or the electrode on the substrate side ( Embedded SOI substrate). By using this structure, wiring or electrodes can be formed by separating the insulator,
Junction leakage can be reduced as compared with the case where the impurity diffusion layer 161 shown in FIG. 48 is used (when pn junction separation is used). In particular, it is possible to reduce the junction leak in the high temperature region.

(B) In particular, on the upper surface of the substrate 1, the lower layer side insulator thin film 18, the conductive thin film 19, and the upper layer side insulator thin film 20.
And the wiring patterns 23 and 25 of the first fixed electrode and the wiring patterns 23 and 25 of the second fixed electrode are formed by the conductive thin film 19.
0 through the openings 29a to 29d, 31a to 31d and the anchor portion of the fixed electrode, the first and second fixed electrode wiring patterns 22 to 25 and the first and second fixed electrodes 9a.
-9d, 11a-11d, 13a-13d, 15a-1
5d was electrically connected. In this way, the insulating film is arranged on the upper surface of the substrate 1, and the thin film wiring patterns 22 to
It is possible to embed 25 and use the wiring patterns 22 to 25 to intersect the first fixed electrode energization line and the second fixed electrode energization line.

As described above, by using the SOI substrate (embedded SOI substrate) using the embedded thin film (polysilicon layer) as the wiring on the substrate side, the wiring can be formed by the insulation separation. Therefore, the conductive thin film separated by the insulator thin film can be formed, and the junction leak can be reduced as compared with the case where the impurity diffusion layer 161 shown in FIG. 48 is used (the case of the pn junction separation). In particular, it is possible to reduce the junction leak in the high temperature region.

Further, a laminated body 21 of the lower insulating film 18, the conductive thin film 19 and the upper insulating thin film 20 is arranged on the upper surface of the substrate 1, and the conductive thin film 19 serves as a first fixed electrode. The wiring patterns 22 and 24 and the wiring patterns 23 and 25 of the second fixed electrode are formed, and the conductive thin film 19 is formed.
Lower electrode (fixed electrode for canceling electrostatic force) 26 is formed, and openings 29a to 29 in upper insulator thin film 20 are formed.
d, 31a to 31d and the anchor portions 10a to 10d, 12a to 12d of the first and second fixed electrodes,
Wiring patterns 22 to 25 of the second fixed electrode and the first and second
Fixed electrodes 9a to 9d, 11a to 11d, 13a to 13
d, 15a to 15d are electrically connected, and further, the lower electrode 26 and the beam structure 2 are connected through the opening 33 in the upper insulating film 20 and the anchor portions 3a to 3d of the beam structure.
And were electrically connected. In this way, the insulating film is arranged on the upper surface of the substrate 1, and the thin film wiring patterns 22 to 2 are arranged therein.
5 and the lower electrode 26 are buried, the first fixed electrode energization line and the second fixed electrode energization line can be crossed using this wiring pattern, and the beam structure (movable part) and the lower electrode Can be made equal potential to cancel the electrostatic force generated between the beam structure (movable part) and the substrate, and the beam structure (movable part) due to a slight potential difference between the beam structure (movable part) and the substrate. Can be prevented from adhering to the substrate.

(D) Since the beam structure 2 is made of single crystal silicon, which is a brittle material with known physical properties such as Young's modulus, the reliability of the beam structure 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 range as in the case of pn junction separation.

(F) Since the servo mechanism (servo control) is adopted, the displacement of the beam structure due to the action of acceleration can be minimized, and therefore the reliability of the sensor can be improved.

As an application example of this embodiment, in the above-mentioned example, the conductive thin film 19 is used to form the wiring patterns 22 and 24 of the first fixed electrode and the wiring patterns 23 and 24 of the second fixed electrode.
25 is formed, but only one of them is formed into a conductive thin film 1.
9 and the other may be electrically connected by aluminum wiring or may be electrically connected as a comb-shaped electrode. Further, in the above-mentioned example, the wiring pattern of the fixed electrode and the lower electrode are formed by the embedded conductive thin film, but they may be embodied in a sensor that does not use the lower electrode.

(Second Embodiment) Next, a second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

17 to 27 are sectional views showing a process flow in manufacturing the semiconductor acceleration sensor according to the present embodiment. First, as shown in FIG. 17, a single crystal silicon substrate 60 as a first semiconductor substrate is prepared. Then, a groove is formed in the silicon substrate 60 with a constant width by trench etching, and then a groove pattern 61 for forming a beam structure is formed. That is, the silicon substrate 60
A groove (61) is formed in a predetermined area in. Here, impurities are introduced by phosphorus diffusion or the like so as to serve as electrodes for detecting electrostatic capacity later. Then, as shown in FIG. 18, a silicon oxide film 62 as a sacrificial layer thin film is formed on the silicon substrate 60 including the groove (61) by a CVD method or the like, and the surface of the silicon oxide film 62 is flattened. Turn into.

Further, as shown in FIG. 19, the silicon oxide film 62 is partially etched through photolithography to form a recess 63. This is to reduce the attachment area in order to prevent the beam structure from being attached to the substrate due to surface tension or the like after the beam structure is released in the sacrifice layer etching step. Further, a silicon nitride film (first insulator thin film) 64 is formed to increase the unevenness of the surface and serve as an etching stopper at the time of sacrifice layer etching. Then, openings 65a, 65b, 65c are formed in the anchor portion formation region by dry etching or the like through photolithography on the laminated body of the silicon nitride film 64 and the silicon oxide film 62. The openings 65a to 65c are for connecting the beam structure and the substrate (lower electrode), and for connecting the fixed electrode (and electrode extraction portion) and the wiring pattern.

Subsequently, as shown in FIG. 20, the opening 6
A polysilicon thin film 66 is formed on the silicon nitride film 64 including 5a to 65c, impurities are then introduced by phosphorus diffusion or the like, and the wiring pattern 66a, the lower electrode 66b, and the anchor portion 66c are further formed by photolithography. Form. Thus, the impurity-doped polysilicon thin film (66) as a conductive thin film is formed in a predetermined region on the silicon nitride film 64 including the openings 65a to 65c. The thickness of the polysilicon thin film is about 1 to 2 μm.

This step (the silicon nitride film 6 including the opening)
4 in a predetermined region on the impurity-doped polysilicon thin film 66.
In the step of forming), the polysilicon thin film 66 is thin enough to satisfy the lower pattern resolution of the stepper (1 to 1).
2 μm), the shape of the openings 65a to 65d of the silicon nitride film 64 under the polysilicon thin film 66 can be seen through, and photomask alignment can be performed accurately.

Then, as shown in FIG. 21, a silicon oxide film 67 as a second insulator thin film is formed on the silicon nitride film 64 including the polysilicon thin film (66). Further, as shown in FIG. 22, a silicon oxide film 67 is formed.
A polysilicon thin film 68 as a thin film for bonding is formed on the above, and the surface of the polysilicon thin film 68 is planarized by mechanical polishing or the like for bonding.

Next, as shown in FIG. 23, a single crystal silicon substrate (supporting substrate) 69 different from the silicon substrate 60 is prepared, and the surface of the polysilicon thin film 68 and the silicon substrate 69 as the second semiconductor substrate are prepared. And paste together.

Further, as shown in FIG. 24, the silicon substrates 60 and 69 are turned upside down and the silicon substrate 60 side is subjected to mechanical polishing or the like to be thinned. That is, the silicon substrate 6
Polish 0 to the desired thickness. At this time, as shown in FIG. 17, when polishing is performed to the depth of the groove formed by trench etching, the hardness of the polishing changes because the layer of the silicon oxide film 62 appears, so that the polishing end point can be easily detected. You can

Thereafter, as shown in FIG. 25, an interlayer insulating film 70 is formed, and a contact hole 71 is formed by dry etching or the like through photolithography. Then, the silicon nitride film 7 is formed in a predetermined region on the interlayer insulating film 70.
Form 7.

Further, as shown in FIG. 26, an aluminum electrode 72 is formed by film formation / photolithography, and then a passivation film 73 is formed by film formation / photolithography.

Finally, as shown in FIG. 27, the silicon oxide film 62 is removed by etching with an HF-based etching solution to make the beam structure 75 having the movable electrode 74 movable.
That is, the silicon oxide film 62 in a predetermined region is removed by sacrifice layer etching using an etching solution, and the silicon substrate 60 has a movable structure. At this time, in order to prevent the movable part from sticking to the substrate during the drying process after etching, a sublimation agent such as valadichlorobenzene is used.

In this step (step of removing the silicon oxide film 62 in a predetermined area by sacrificial layer etching using an etching solution to make the silicon substrate 60 a movable structure),
The anchor portion 66c in the movable portion is made of a conductive thin film, and etching stops at the anchor portion 66c, eliminating variations. That is, in the present example in which the silicon oxide film is used as the sacrificial layer thin film and the polysilicon thin film is used as the conductive thin film, when the HF-based etching solution is used, the silicon oxide film is melted in HF, but the polysilicon thin film is used. Since it does not melt, it is not necessary to precisely control the concentration and temperature of the HF-based etching solution or to control the end of etching with precise time control, which facilitates manufacturing.

Since the anchor can be formed in this way, it is possible to facilitate the control of the spring constant and the like without the need to perform the end point control by the time control in the sacrifice layer etching step when releasing the beam structure. Become.

In this way, the embedded SOI substrate can be used to form the wiring pattern and the lower electrode by insulating material isolation to form a servo-controlled acceleration sensor.

(Third Embodiment) Next, a third embodiment will be described with a focus on differences from the first embodiment.

FIG. 28 shows a plan view of the semiconductor acceleration in this embodiment. In the first embodiment shown in FIG. 1, the mass portion 6 has a structure in which it is supported by beams 4 and 5 extending linearly with respect to the anchor portions 3a to 3d. In the above embodiment, a bent beam structure as shown in FIG. 28 is used.

By doing so, when the compressive stress remains in the film, it is possible to prevent the beam from buckling due to the residual stress of the film used for the beam structure 2. Further, when tensile stress remains in the film, it is possible to prevent the spring constant of the beam from deviating from the designed value. As a result, it is possible to form a sensor as designed.

(Fourth Embodiment) Next, a fourth embodiment will be described with reference to the drawings.

This embodiment is applied to an excitation type yaw rate sensor, and more specifically, two beam structures (movable structures) are provided, and both beam structures (movable structures) are set in opposite phases. It excites and makes a differential detection.

FIG. 29 is a plan view of the yaw rate sensor according to the present embodiment, and FIG. 30 is a diagram of FIG.
FIG. 31 is a sectional view taken along the line XXX, and FIG. 31 is XXXI in FIG. 29.
FIG. 32 is a sectional view taken along line XXXI, and FIG.
It is a XII-XXXII sectional view.

In FIG. 30, a beam structure 8 made of single crystal silicon (single crystal semiconductor material) is formed on the upper surface of the substrate 80.
1 and the beam structure 82 (see FIG. 29) are arranged adjacent to each other. The beam structure 81 projects from the substrate 80 side 4
The anchor portions 83a, 83b, 83c, and 83d are provided so as to extend over the upper surface of the substrate 80, and are arranged at predetermined intervals. Anchor portions 83a to 83d
Is a polysilicon thin film. A beam portion 84 is installed between the anchor portion 83a and the anchor portion 83c, and
The beam portion 85 is provided between the anchor portion 83b and the anchor portion 83d.
Has been erected. A rectangular mass portion (mass portion) 86 is provided between the beam portion 84 and the beam portion 85. The mass portion 86 is provided with a through hole 86a penetrating vertically. Further, from the one side surface (the left side surface in FIG. 29) of the mass portion 86, a large number of exciting movable electrodes 8 are formed.
7 is protruding. Each of the movable electrodes 87 has a rod shape,
It extends in parallel at equal intervals. A large number of exciting movable electrodes 88 project from the other side surface (right side surface in FIG. 29) of the mass portion 86. Each movable electrode 88 has a rod shape and extends in parallel at equal intervals.
Here, the beam portions 84 and 85, the mass portion 86, the movable electrode 87,
88 is made movable by removing a part of the sacrifice layer oxide film 89 by etching. This etching area is shown in FIG.
It is indicated by Z2 in 9.

As described above, the beam structure 81 has two comb-teeth-shaped movable electrodes, that is, the movable electrode 87 as the first movable electrode and the movable electrode 88 as the second movable electrode. There is.

The structure similar to that of the beam structure 81 is also adopted in the beam structure 82, and the description thereof will be omitted by giving the same reference numerals. Comb-shaped electrodes 90, 91, 92 as fixed electrodes for excitation are arranged on the upper surface of the substrate 80. The comb-teeth electrode 90 has a rod-shaped electrode portion 90a on one side, the comb-teeth electrode 91 has rod-shaped electrode portions 91a and 91b on both sides, and the comb-teeth electrode 92 has a rod-shaped electrode portion 92a on one side. The comb electrodes 90, 91, 92 are made of single crystal silicon. The comb electrodes 90, 91, 92 are supported and fixed by anchor portions 93, 94, 95 protruding from the substrate 80 side. The rod-shaped electrode portions 90 a of the comb-teeth electrode 90 are arranged to face each other between the movable electrodes (rod-shaped portions) 87 of the beam structure 81. The rod-shaped electrode portions 91 a of the comb-teeth electrode 91 are arranged to face each other between the movable electrodes (rod-shaped portions) 88 of the beam structure 81. The rod-shaped electrode portion 91b of the comb-teeth electrode 91 is opposed to and disposed between the movable electrodes (rod-shaped portions) 87 of the beam structure 82. The rod-shaped electrode portion 92 a of the comb-teeth electrode 92 is opposed to and arranged between the movable electrodes (rod-shaped portions) 88 of the beam structure 82.

In the present embodiment, the comb-teeth electrode 90 constitutes the first excitation fixed electrode, and the comb-teeth electrode 91 constitutes the second excitation fixed electrode. Further, as shown in FIG. 29, in a region facing a part of the beam structure 81 (mainly the mass part 86) on the upper surface of the substrate 80, a lower electrode (for yaw rate detection) as a fixed electrode for mechanical quantity detection is used. (Fixed electrode) 101 is arranged. Similarly, a lower electrode (fixed electrode for yaw rate detection) 102 as a fixed electrode for mechanical quantity detection is arranged in a region facing a part (mainly the mass portion 86) of the beam structure 82 on the upper surface of the substrate 80. Has been done. A first capacitor is provided between the beam structure 81 and the lower electrode 101,
Further, a second capacitor is formed between the beam structure 82 and the lower electrode 102.

Then, between the movable electrode 87 of the beam structure 81 and the comb-teeth electrode 90, and between the movable electrode 8 of the beam structure 81.
The beam structure 81 can be forcedly vibrated (excited) by applying an electrostatic force of opposite phase between the electrode 8 and the comb-teeth electrode 91. In addition, the movable electrode 87 of the beam structure 82 and the comb-teeth electrode 91
The beam structure 82 can be forcedly vibrated (excited) by applying an electrostatic force of opposite phase between the movable electrode 88 of the beam structure 82 and the comb electrode 92 of the beam structure 82. Further, during this excitation, the yaw rate acting on the beam structures 81, 82 is detected based on the capacitance (electrostatic capacitance Co) of the capacitor formed between the beam structures 81, 82 and the lower electrodes 101, 102. You can do it.

As shown in FIG. 31, the substrate 80 has a structure in which a lower insulating film 97, a conductive thin film 98, and an upper insulating thin film 99 are laminated on a silicon substrate (semiconductor substrate) 96. Has become. That is, it has a structure in which the laminated body 100 of the lower insulating film 97, the conductive thin film 98, and the upper insulating thin film 99 is arranged on the upper surface of the silicon substrate 96, and the conductive thin film 98 is the insulating thin film. It is configured to be embedded inside 97 and 99. The lower layer side insulator thin film 97 is made of a silicon oxide film.
9 is made of a silicon nitride film and is formed by the CVD method or the like. The conductive thin film 98 is made of an impurity-doped polysilicon thin film.

The conductive thin film 98 forms the lower electrodes (fixed electrodes for yaw rate detection) 101, 102 and the wiring patterns 103, 104 shown in FIG. or,
As shown in FIGS. 29 and 31, on the upper surface of the substrate 80, electrode extraction portions 105 and 106 made of single crystal silicon are formed, and the electrode extraction portions 105 and 106 are supported by anchor portions 107 and 108 protruding from the substrate 80. Has been done. In the present embodiment, the electrode lead-out parts 105 and 106 form an electrical connection member.

As shown in FIG. 31, the upper insulator thin film 9 is formed.
An opening 109 is formed in the opening 9, and the anchor portion (impurity-doped polysilicon) 107 described above is arranged in the opening 109. Therefore, the lower electrode 101 passes through the opening portion 109 and the anchor portion (impurity-doped polysilicon) 107 and the electrode lead-out portion 1 through the wiring pattern 103.
05 is electrically connected. A similar structure is also adopted in the electrode extraction portion 106, and the lower electrode 10 is inserted through the anchor portion (impurity-doped polysilicon) 108.
2 is electrically connected to the electrode extraction portion 106 via the wiring pattern 104.

As shown in FIG. 29, the comb electrodes 90,
91, 92 anchor portions 93, 94, 95 and beam structure 81, 82 anchor portions 83a, 83b, 83c, 8
Also in 3d, the embedded portion 110 made of the conductive thin film 98.
Are formed.

As described above, the substrate 80 includes the lower electrodes 101 and 102 made of polysilicon and the wiring pattern 1
03 and 104 are buried under the SOI layer, and this structure is formed by using the surface micromachining technique.

On the other hand, as shown in FIG. 32, the comb-teeth electrode 9
Electrodes (bonding pads) 111, 112, 113 made of an aluminum thin film are provided on the upper surfaces of 0, 91, 92. Further, electrodes (bonding pads) 114 and 115 made of an aluminum thin film are provided on the upper surfaces of the anchor portions 83a of the beam structures 81 and 82. Further, as shown in FIG. 31, electrodes (bonding pads) 116 made of an aluminum thin film are provided on the upper surfaces of the electrode extraction portions 105 and 106, respectively. An interlayer insulating film 118 and a silicon nitride film 117 are formed on the electrode extraction portions 105 and 106.

Lower electrode 1 separated from the insulator as described above
By using 01 and 102 and the wiring patterns 103 and 104, the aluminum electrode (bonding pad) 116 can be taken out from the substrate surface.

Next, the detection principle of this yaw rate sensor will be described with reference to FIG. Comb-shaped electrode (fixed electrode for excitation)
A voltage is applied between 90, 91, 92 and the excitation movable electrodes 87, 88. As a result, the mass portion 86 of the beam structure 81, 82 is vibrated in the direction parallel to the surface of the substrate (Y direction in FIG. 29). At this time, when yaw Ω is generated in a direction parallel to the surface of the substrate and perpendicular to the vibration direction (Y direction), a direction perpendicular to the surface of the substrate with respect to the mass portion 86 of the beam structures 81 and 82. Coriolis force is generated (see FIG. 29). The displacement of the mass portion 86 of the beam structure 81, 82 due to the Coriolis force is detected as a change in the capacitance Co.

Here, the Coriolis force fc is the beam structure 81,
It depends on the mass m of the mass part 86 of 82, the speed V of vibration, and the yaw Ω, and is represented by the following formula.

Fc = 2 mVΩ (1) In the vibration in the direction parallel to the substrate surface, the beam structures 81, 8
Since the velocity of the second mass portion 86 is “0” at the fixed end side and is maximum at the center, the Coriolis force is also the same, and as shown in FIG. 33, the displacement in the direction perpendicular to the surface of the substrate is “at the fixed end side”. 0 ”, which is the maximum at the center, and the mass portion 86 of the beam structure 81, 82 draws an ellipse. Here, the mass portions 86 (that is, the two mass portions 86) of the beam structures 81 and 82 have their displacement directions reversed by shifting the phase of vibration by 180 degrees, and differential detection becomes possible. If the mass portions 86 of the beam structures 81 and 82 are independent (without differential excitation), acceleration due to Coriolis force and vibration cannot be separated, but noise detection due to acceleration can be canceled by performing differential detection. . Generally, the Coriolis force is very small, so the effect of resonance is used. Specifically, in order to increase the velocity V shown in the equation (1), the excitation (in the direction parallel to the surface of the substrate) of the mass portion 86 of the beam structures 81 and 82 is set as the resonance frequency to increase the amplitude.
Here, since the Coriolis force is generated in the same cycle as the vibration, if the detection (perpendicular to the surface of the substrate) also has a resonance frequency equal to the excitation, the displacement due to the Coriolis force can be increased.

Here, as shown in FIG. 33, one of the electrostatic capacitances is "C" due to the gap change due to the Coriolis force.
o + ΔC ”and the other becomes“ Co−ΔC ”,
If the gap change due to the Coriolis force is sufficiently smaller than the initial value, the Coriolis force fc becomes fc∝2ΔC by differential detection, and the yaw Ω is set as Ω∝2ΔC, and yaw is detected from the change in the two capacitances. be able to.

This yaw rate sensor can be manufactured by the same method as in the first and second embodiments. As described above, the present embodiment has the following features.

On the upper surface of the substrate 80, the lower insulating thin film 9 is formed.
7 and the conductive thin film 98 and the upper insulator thin film 99 are arranged on the laminated body 100, and the conductive thin film 98 is used to form the lower electrode (fixed electrode for mechanical quantity detection) 101 (102) and the wiring pattern 103 (104) of the lower electrode. ) Is formed, and the wiring pattern 103 is formed from the opening 109 in the upper insulator thin film 99.
The lower electrode 101 (102) is formed on the substrate 8 through (104)
Electrode extraction part (electrical connection member) 105 (106) above 0
Electrically connected to. In this way, by disposing the insulating film on the upper surface of the substrate 80 and burying the thin film lower electrode (fixed electrode for detecting the mechanical quantity) and the wiring pattern in the insulating film, the wiring or the electrode can be formed by the insulator separation. The junction leak can be reduced as compared with the case where the impurity diffusion layer 161 shown in FIG. 48 is used (when the pn junction separation is used). In particular, it is possible to reduce the junction leak in the high temperature region.

Thus, the lower electrodes 101, 1 on the substrate side
02 and an SOI substrate (embedded SOI substrate) using a buried thin film (polysilicon layer) as its wiring, an electrode and its wiring can be formed by insulator separation.

The present invention is not limited to the above-mentioned embodiments. For example, in the above-mentioned embodiment, the acceleration is detected by using the electrostatic servo system (the voltage is applied to the displacement due to the acceleration). Although it is detected by applying an electrostatic force that does not cause displacement), it may be embodied as a sensor that directly detects displacement as a capacitance change.

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

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

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

FIG. 6 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 7 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 8 is a sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 9 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 10 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 11 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 12 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 13 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 14 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 15 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 16 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the first embodiment.

FIG. 17 is a sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 18 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 19 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 20 is a sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 21 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 22 is a sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 23 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 24 is a sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 25 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 26 is a sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 27 is a cross-sectional view showing the method of manufacturing the acceleration sensor according to the second embodiment.

FIG. 28 is a plan view of the acceleration sensor according to the third embodiment.

FIG. 29 is a plan view of the yaw rate sensor according to the fourth embodiment.

30 is a sectional view taken along the line XXX-XXX in FIG. 29.

31 is a sectional view taken along the line XXXI-XXXI in FIG. 29.

32 is a sectional view taken along the line XXXII-XXXII of FIG. 29 (Ω
= 0).

FIG. 33 is a cross-sectional view for explaining the operation of the yaw rate sensor according to the fourth embodiment (when Ω ≠ 0).

FIG. 34 is a plan view showing a conventional acceleration sensor.

35 is a sectional view taken along the line XXXV-XXXV in FIG. 34.

36 is a sectional view taken along the line XXXVI-XXXVI of FIG. 34.

FIG. 37 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

FIG. 38 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

FIG. 39 is a plan view showing a conventional acceleration sensor.

40 is a cross-sectional view taken along the line XXXX-XXXX in FIG. 39.

41 is a cross-sectional view taken along the line XXXXI-XXXXI of FIG. 39.

FIG. 42 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

FIG. 43 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

FIG. 44 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

FIG. 45 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

FIG. 46 is a cross-sectional view showing the method of manufacturing the conventional acceleration sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Beam structure as an electric connection member, 7a, 7b, 7c, 7d ... Movable electrode, 8a, 8b, 8c, 8d ... Movable electrode, 9a, 9b, 9c, 9d ... 1st fixed electrode , 10a, 10b, 10c, 10d ... Anchor portion, 11a, 11b, 11c, 11d ... Second fixed electrode, 12a, 12b, 12c, 12d ... Anchor portion, 13a, 13b, 13c, 13d ... First fixed electrode , 14a, 14b, 14c, 14d ... Anchor part, 15a, 15b, 15c, 15d ... Second fixed electrode, 16a, 16b, 16c, 16d ... Anchor part, 17 ... Silicon substrate as semiconductor substrate, 18 ... Lower layer side Insulator thin film, 19 ... Conductive thin film, 20 ... Upper layer side insulator thin film, 21 ... Laminated body, 22, 23, 24, 25 ... Wiring pattern, 26 ... Electrostatic force cancellation fixed voltage Electrode, as an electrical connection member, 29a, 29b, 29c, 29d ... Opening part, 31a, 31b, 31c, 31d ... Opening part, 32 ... Opening part, 33 ... Openings, 40 ... Single crystal silicon substrate as first semiconductor substrate, 41 ... Silicon oxide film as sacrificial layer thin film, 43 ... Silicon nitride film as first insulator thin film, 44a, 44b, 44c, 44d ... Opening part, 45 ... Polysilicon thin film as conductive thin film, 46 ... Silicon oxide film as second insulator thin film, 46 ... Polysilicon thin film as bonding thin film, 48 ... As second semiconductor substrate Single crystal silicon substrate, 49 ... Groove pattern (groove), 60 ... Silicon substrate as first semiconductor substrate, 61 ... Groove pattern (groove), 62 ... For sacrificial layer Silicon oxide film as a thin film, 64 ... Silicon nitride film as a first insulator thin film, 65a, 65b, 65c ... Opening portion, 66 ... Polysilicon thin film as a conductive thin film, 67 ... As a second insulator thin film , A polysilicon thin film as a laminating thin film, 69 ... Single crystal silicon substrate as a second semiconductor substrate, 80 ... Substrate, 81 ... Beam structure, 82 ... Beam structure, 87 ... Exciting movable electrode as 1 movable electrode, 88 ... Exciting movable electrode as second movable electrode, 90 ... Comb tooth electrode as first exciting fixed electrode, 91 ... As second exciting fixed electrode Electrode ... 97 ... Lower layer side insulator thin film, 98 ... Conductive thin film, 99 ... Upper layer side insulator thin film, 100 ... Layered body, 101 ... Lower electrode, 102 ... Lower electrode, 103 ... Wiring pattern, 104 Wiring Patan, 105 ... electrode lead-out portion of the electric connection member, 106 ... electrode lead-out portion of the electric connection member, 109 ... opening.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-213924 (JP, A) JP-A-4-337468 (JP, A) JP-A-6-347474 (JP, A) JP-A-6- 151889 (JP, A) JP-A-7-183543 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01P 15/125-15/13

Claims (2)

(57) [Claims] 1. A substrate, a beam structure made of a semiconductor material, which is arranged at predetermined positions on the upper surface of the substrate and receives an acting force that is displaced by a mechanical amount, and is fixed to the upper surface of the substrate. A semiconductor dynamical quantity sensor comprising a fixed electrode arranged so as to face at least a part of the beam structure, wherein the semiconductor dynamic quantity sensor has an upper surface part of the substrate and a part corresponding to a lower part of the beam structure. , A lower electrode electrically connected to the beam structure
A surface of the lower electrode on which the beam structure is arranged, with a pole arranged
The semiconductor dynamic quantity sensor, characterized in that the formation of the protrusions. 2. The semiconductor dynamic quantity sensor according to claim 1, wherein the beam structure is made of single crystal silicon.