JP2002148278A - Semiconductor kinetic quantity sensor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fixing of beam structure and substrates during beam structure formation. SOLUTION: A semiconductor kinetic quantity sensor is provided with a beam structure 56, constituted of a substrate 48 and a semiconductor material and arranged at a position remote by a prescribed distance on the substrate upper surface, and fixed electrodes fixed on the upper surface of the substrate 48 and is arranged facing to at least one part of the beam structure 56.

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 part having a beam structure.
The present invention relates to a semiconductor dynamic quantity sensor for detecting a dynamic quantity such as a yaw rate and vibration and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, the basic principle of a dynamic quantity sensor such as an acceleration sensor is to measure displacement or force when a dynamic quantity acts on a mass (mass) 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 and cost reduction of dynamic quantity sensors such as acceleration sensors used for suspension control of automobiles, airbags, and the like. For this reason,
Japanese 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.
This will be described with reference to FIGS. FIG. 34 shows a plan view of the sensor, and FIG. 35 shows XXXV-XX in FIG.
An XV cross-sectional view is shown in FIG. 36, and XXXVI-X in FIG.
XXVI sectional drawing is shown.

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

The principle of detection 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 capacitances C1 and C2 between them are equal. Also, the movable electrode 134
And fixed electrodes 135a and 135b are applied with voltages V1 and V2, and when no acceleration occurs, V1 =
V2, and the movable electrode 134 is connected to the fixed electrodes 135a and 135a.
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
b and the capacitances C1 and C2 become unequal. At this time, if, for example, the movable electrode 134 is displaced toward the fixed electrode 135a so that the capacitances become equal, the voltage V1 decreases and the voltage V2 increases. Accordingly, 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 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.

[0006] Manufacturing is performed in steps shown in FIGS. As shown in FIG. 37, a sacrificial layer (silicon oxide film) 138 is deposited on a silicon substrate 137, and an opening 139 is provided in a predetermined region. The opening 139
The polysilicon thin film 140 is deposited on the sacrificial layer 138 containing, 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 an air gap 141, thereby obtaining a beam structure made of the polysilicon thin film 140.

Here, 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, such polycrystalline silicon has a problem in that its mechanical properties are unknown, and the mechanical reliability is lower than that of single crystal silicon. Further, there is a problem of warpage of the beam structure due to internal stress and stress distribution generated when polycrystalline silicon is formed on a silicon oxide film on a single crystal silicon substrate. Due to these problems, problems such as difficulty in creating a beam structure and a change in the spring constant of the sensor have occurred.

On the other hand, SOI (Silicon)
A single crystal silicon is used as a beam structure using an on-insulator substrate, so that mechanical reliability can be improved. This type of sensor is shown in FIGS.
Description will be made using 0 and 41. FIG. 39 shows a plan view of the sensor, and FIG. 40 shows XXXX-XX in FIG.
FIG. 41 is a cross-sectional view taken along the line XX of FIG.
XXXI cross-sectional view is shown.

In this acceleration sensor, a vibrating mass 147 is joined to a fixed support 146 by a flexible beam 145, and the vibrating mass 147 can move. The vibrating mass 147 is made of single crystal silicon doped with phosphorus. The fixed support 146 is fixed on the substrate 148 in an electrically insulated state. Vibrating mass 14
7 has a movable electrode 149 extending in a direction parallel to each other. These members 145, 146, 147, and 149 constitute a beam structure 150. Also, movable electrode 1
Fixed electrodes 151 and 152 are arranged to face 49, and a capacitance is formed between movable electrode 149 and fixed electrodes 151 and 152. The beam 145 is applied to the substrate 1
When the movable electrode 149 is displaced in a direction (Y-axis direction in FIG. 39) parallel to the surface of the movable electrode 148, the capacitance changes.

Next, a method of manufacturing the 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 ⁺ ) is added to single crystal silicon substrate 1
10 ¹⁶ to 1 at 100 keV to 1000 keV for 48
0 ¹⁸ dose / cm ^{2 is} implanted, and 1150 ° C. to 1400 ° C.
Heat treatment. Thus, 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. Then, 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, single-crystal silicon layer 155 is formed to a thickness of 1 μm to 100 μm by epitaxial growth.
(Typically 10 to 20 μm). Next, as shown in FIG. 45, after forming an electrode 156 made of a metal for connection to a measurement circuit, the electrode 156 is formed into a predetermined electrode shape through photolithography. Further, as shown in FIG. 46, reactive gas phase dry etching or the like is performed on the silicon layer 155 to form fixed electrodes 151 and 152, a 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, which is a beam structure, is used.
There is a problem that the etchant remains between the substrate and the substrate 148 and the like, and both are fixed.

An object of the present invention is to provide a semiconductor dynamic quantity sensor having a beam structure formed on a substrate, which can prevent the beam structure from being fixed to the substrate when the beam structure is formed. It is to provide a physical quantity sensor.

[0013]

According to a first aspect of the present invention, there is provided a beam comprising a substrate and a semiconductor material, the beam being disposed at a predetermined interval on an upper surface of the substrate and receiving an acting force displaced by a mechanical quantity. Fixed to the structure and the top surface of the substrate,
A semiconductor dynamic quantity sensor including a fixed electrode disposed so as to face at least a part of the beam structure, wherein a projection is formed on a portion corresponding to a lower portion of the beam structure on an upper surface of the substrate. It is characterized by being formed.

Since the projections are formed at the lower portion of the beam structure as described above, the area of attachment between the beam structure and the substrate during the formation of the beam structure is reduced, and the adhesion between the two can be prevented.

According to a second aspect of the present invention, the beam structure is made of single crystal silicon. By using single-crystal silicon, which is a brittle material whose physical properties such as Young's modulus are known, as the material of the beam structure, the reliability of the beam structure can be increased.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, the present invention is applied to a semiconductor acceleration sensor. More specifically, the present invention is applied to a servo-controlled differential capacitive semiconductor dynamic quantity sensor.

FIG. 1 is a plan view of a semiconductor acceleration sensor according to the present 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.
1 is a sectional view taken along line IV-IV in FIG. 1, and FIG. 5 is a sectional view taken along line VV in FIG.

1 and 2, on the upper surface of the substrate 1,
A beam structure 2 made of single crystal silicon (single crystal semiconductor material) is arranged. The beam structure 2 is bridged by four anchor portions 3a, 3b, 3c, 3d protruding from the substrate 1 side, and is arranged at a predetermined interval on the upper surface of the substrate 1. Anchor parts 3a, 3b, 3c,
3d is made of a polysilicon thin film. A beam 4 is provided between the anchors 3a and 3b, and a beam 5 is provided between the anchors 3c and 3d. A rectangular mass part (mass part) 6 is provided between the beam part 4 and the beam part 5. The mass part 6 is provided with a through-hole 6a penetrating vertically, and the through-hole 6a makes it easier for the etchant in the sacrificial layer etching to enter. Further, four movable electrodes 7 a, 7 b, 7 c, from one side surface (left side surface in FIG. 1) of the mass portion 6.
7d protrudes. These 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 protrude from the other side surface (the 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 movable by etching and removing a part of the sacrifice layer oxide film 37. This etching region is indicated by Z1 in FIG.

As described above, the beam structure 2 has two comb-shaped movable electrodes. Four first fixed electrodes 9a, 9b, 9c, 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 to 9d are supported by anchor portions 10a, 10b, 10c, and 10d protruding from the substrate 1 side, and are provided on one side surface of each movable electrode (bar-shaped portion) 7a to 7d of the beam structure 2. They are arranged facing each other. On the upper surface of the substrate 1, 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.
The movable electrodes (bar-shaped portions) 7 a to 7 d of the beam structure 2 are arranged so as to face each other.

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

As shown in FIG. 2, the substrate 1 is provided on a silicon substrate (semiconductor substrate) 17 on a lower insulating thin film 1.
8, a conductive thin film 19, and an upper insulator thin film 20. That is, the laminated body 21 of the lower insulating thin film 18, the conductive thin film 19, and the upper insulating thin film 20 is arranged on the upper surface of the silicon substrate 17. It is configured to be embedded inside 18, 20. Lower insulating film 18
Is a silicon oxide film, and the upper insulating thin film 20 is a silicon nitride film 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 four wiring patterns 22, 23, 24 and 25 shown in FIG. 1 and also forms 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 formed in a band shape as shown in FIG. 1 and extend in an L-shape. The wiring pattern 23 includes the second fixed electrodes 11a, 11b, 11c, 11d.
Wiring pattern as shown in FIG.
And it is extended in L shape. Similarly, the wiring pattern 24 includes the first fixed electrodes 13a, 13b, 13c, 13d.
And the wiring pattern 25 is the second fixed electrode 15
The wires a, 15b, 15c, and 15d are formed in a band shape as shown in FIG. 1 and extend in an L-shape. The lower electrode 26 is formed in a region on the upper surface of the substrate 1 facing the beam structure 2.

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

On the upper surface of the substrate 1, electrode extraction portions 27a, 27b, 27c, 27d made of single crystal silicon are formed, and the electrode extraction portions 27a, 27b, 27c, 27d are anchor portions 28a protruding from the substrate 1. , 28b, 28
c, 28d.

As shown in FIG. 3, as shown in FIG.
Have openings 29a, 29b, 29c, 29d and 30
Is formed, and the above-described anchor portion (impurity-doped polysilicon) 1 is formed in the openings 29a, 29b, 29c, and 29d.
0a to 10d are arranged. Further, an anchor portion (impurity-doped polysilicon) 28a is disposed in the opening 30. Therefore, openings 29a to 29d and anchor portions (impurity-doped polysilicon) 10a to 10d
d through the wiring pattern 22 and the first fixed electrodes 9a to 9
d is electrically connected, and the wiring pattern 22 and the electrode extraction portion 27a are electrically connected through the opening 30 and the anchor portion (impurity-doped polysilicon) 28a.

As shown in FIG. 4, as shown in FIG.
Are formed with openings 31a, 31b, 31c, 31d, 32. The anchor portions (impurity-doped polysilicon) 12a to 12d are provided in the openings 31a to 31d.
However, the above-described anchor portion 28c is disposed in the opening portion 32. Therefore, the openings 31a to 31d and the anchors (impurity-doped polysilicon) 12a to 12d
Through the wiring pattern 23 and the second fixed electrodes 11a to 11a
1d is electrically connected, and the wiring pattern 23 and the electrode extraction 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 electrodes 13a to 13d through the openings (not shown) in the upper insulating thin film 20 and the anchor portions 14a to 14d of the first fixed electrode. 13d is electrically connected, and the wiring pattern 24 and the electrode extraction portion 27b are electrically connected through the anchor portion 28b.
Further, the wiring pattern 25 of the second fixed electrode and the second fixed electrodes 15a to 15d are electrically connected to each other through an opening (not shown) in the upper insulating thin film 20 and the anchor portions 16a to 16d of the second fixed electrode. And the wiring pattern 25 and the electrode extraction portion 27d are electrically connected through the anchor portion 28d.

As shown in FIG. 2, an opening 33 is formed in the upper insulating thin film 20, and the above-mentioned anchor portions (impurity-doped polysilicon) 3a to 3d are formed in the opening 33.
Is arranged. Therefore, the anchor portion 3a of the beam structure
3d, the lower electrode 26 and the beam structure 2 are electrically connected.

As described above, the substrate 1 is provided with the wiring patterns 22 to 25 and the lower electrode 26 made of polysilicon.
The structure is embedded under the I layer.
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. As shown in FIGS. 1, 3, and 4, electrodes (bonding pads) 35a and 35 made of an aluminum thin film are provided on the upper surfaces of the electrode extraction portions 27a, 27b, 27c, and 27d.
b, 35c and 35d are provided respectively. Note that 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 film 38,3
6 is formed in a region other than Z1 in FIG.

The movable electrodes 7a to 7d of the beam structure 2
And the capacitance of the first capacitor formed between the first fixed electrodes 9a to 9d (and the capacitance of the first capacitor formed between the movable electrodes 8a to 8d and the first fixed electrodes 13a to 13d). Capacity), and the movable electrodes 7 a to 7 b 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 first fixed electrode 15a and the second fixed electrodes 15a to 15d. 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 26 equal, the electrostatic force generated between the beam structure 2 and the substrate 1 is canceled. That is, since the lower electrode 26 is electrically connected to the beams 4, 5 and the mass 6 through the anchors 3a to 3d, the lower electrode 26 is electrically equipotential. Can be prevented. 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 even with a slight potential difference between the beam structure 2 and the silicon substrate 17. Can be prevented.

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

Next, the detection principle of this acceleration sensor is shown in FIG.
This will be described with reference to FIG. Movable electrodes 7a to 7d (8a to 8d)
Are fixed electrodes 9a to 9d (13a to 13d) and 11 on both sides.
Located at the centers of a to 11d (15a to 15d), the capacitances C1 and C2 between the movable electrode and the fixed electrode are equal. The movable electrodes 7a to 7d (8a to 8d) and the fixed electrodes 9a to 9d
The voltage V1 is applied between the movable electrodes 7a to 13d.
7d (8a to 8d) and fixed electrodes 11a to 11d (15a
To 15d), the voltage V2 is applied. And
When no acceleration occurs, V1 = V2, and the movable electrodes 7a to 7d (8a to 8d) are fixed electrodes 9a to 9d.
(13a-13d) and 11a-11d (15a-15
d) with the same 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 changes, and the capacitances C1 and C2 become unequal. At this time, for example, the movable electrodes 7a to 7d (8a to 8d) are fixed electrodes 9a to 9d so that the electrostatic force becomes 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 to the fixed electrodes 11a to 11d (15a to 15d) by electrostatic force.
a to 7d (8a to 8d) are subtracted. Movable electrodes 7a to 7
d (8a to 8d) returns to the center position and the capacitances C1, 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, in the first capacitor and the second capacitor, the displacement caused by the action of the mechanical quantity is
The voltage of the fixed electrode forming the first and second capacitors is controlled so that the movable electrode is not displaced, and the acceleration is detected based on the change in the voltage.

Next, the manufacturing process of this acceleration sensor is shown in FIG.
This will be described with reference to FIGS. 6 to 16 are schematic cross-sectional views showing the manufacturing process along 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 thin film for a sacrificial layer is thermally oxidized on the silicon substrate 40 by CV.
The film is formed by the method D or the like. Then, as shown in FIG. 7, the silicon oxide film 41 is partially etched through photolithography to form a concave portion 42. Further, a silicon nitride film (first insulating thin film) 4 which serves as an etching stopper for increasing surface irregularities and for etching the sacrificial layer 4
3 is formed. Thereafter, openings 44a, 44b, and 44c are formed in the anchor portion forming region by dry etching or the like through photolithography on the stacked body of the silicon oxide film 41 and the silicon nitride film 43. This opening 44
Reference numerals a to 44c 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, as shown in FIG.
A polysilicon thin film 45 serving as a conductive thin film is formed on the silicon nitride film 43 including the layers a to 44c, and then impurities are introduced by phosphorus diffusion or the like, and a wiring is formed in a predetermined region on the silicon nitride film 43 through photolithography. The pattern 45a, the lower electrode 45b, and the anchor 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 a 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 its surface is flattened 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 formed. Paste.

Further, as shown in FIG. 12, the silicon substrates 40 and 48 are turned upside down, and the silicon substrate 40 is thinned to a desired thickness (eg, 1 to 2 μm) by mechanical polishing or the like. Thereafter, a groove is dug 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. Thus, the silicon substrate 4
The unnecessary area (49) at 0 is removed to obtain a desired shape. Here, an impurity is introduced into the silicon substrate 40 by phosphorus diffusion or the like in order to use the silicon substrate 40 as an electrode for detecting capacitance later.

In this step (the step of removing unnecessary regions 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.

Thereafter, as shown in FIG. 13, a silicon oxide film 50 is formed by a 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 after photolithography. Then, the interlayer insulating film 5
Then, a silicon nitride film 76 is formed in a predetermined region on top of the first region.

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

Finally, as shown in FIG. 16, the silicon oxide films 41 and 50 are removed by etching with an HF-based etchant, and the beam structure 56 having the movable electrode 55 and the like 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. 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 sacrificial layer etching using an etching solution to make the silicon substrate 40 a movable structure)
The anchor portion 45c of the movable portion is made of a conductive thin film (polysilicon), and the etching is stopped at the anchor portion 45c, so that 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 etching with accurate time management, thereby facilitating the manufacture.

That is, at the time of etching the sacrificial layer, FIG.
In the case where the SOI substrate shown in FIG. 2 is used, the length of the beam changes depending on the etching time. However, in this embodiment, the etching is selectively completed when the anchor portion is etched regardless of the etching time.
The beam length is always constant.

As described above, since the anchor portion can be formed, it is not necessary to perform the end point control by time control in the sacrificial layer etching step when releasing the beam structure, and it is possible to easily control the spring constant and the like. Becomes

In this sacrificial layer etching step,
Since the projection 57 shown in FIG. 16 is formed by the concave portion 42 of FIG. 7, a rinse liquid (eg, pure water) is applied between the liquid movable part and the substrate in the etching liquid replacement step after the beam structure is released. Although the droplet of the replacement liquid remains, the surface area of the droplet is reduced by reducing the adhesion area of the droplet, thereby preventing the movable portion from sticking to the substrate during the evaporation of the rinsing liquid.

In this way, 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.

As described above, the present embodiment has the following features (b) 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 9
d, 11a to 11d, 13a to 13d, 15a to 15d
Are fixed to the upper surface of the substrate 1 and are disposed so as to face the movable electrodes 7a to 7d and 8a to 8d which are part of the beam structure 2. In this type of sensor, on the upper surface of the substrate 1,
A laminated body 21 of a lower insulating thin film 18, a conductive thin film 19, and an upper insulating thin film 20 shown in FIG. 2 is arranged, and wirings 22 to 25 and an electrode 26 are formed by the conductive thin film 19. To 25 and the electrode 26 are formed in the openings 29a to 29d, 31a to 31d, 3 formed in the upper insulating thin film 20.
Fixed electrodes 9a to 9d, 11a to 11d, 13a to 13d, 15a arranged on the substrate 1 through 0, 32, 33
15d, the beam structure 2, and the electrode extraction portions 27a to 27d (electric connection members). 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 SOI substrate (polysilicon layer) using the buried thin film (polysilicon layer) as the wiring or electrode on the substrate side is used. (Embedded SOI substrate). By using this structure, wiring or electrodes can be formed by insulator separation,
Junction leakage can be reduced as compared with the case where the impurity diffusion layer 161 shown in FIG. 48 is used (in the case of pn junction separation). In particular, it is possible to reduce junction leakage in a high temperature range.

(B) In particular, the lower insulating thin film 18, the conductive thin film 19 and the upper insulating thin film 20 are formed on the upper surface of the substrate 1.
And a wiring pattern 22, 24 of the first fixed electrode and wiring patterns 23, 25 of the second fixed electrode are formed by the conductive thin film 19, and the upper insulating thin film 2 is formed.
0, the first and second fixed electrode wiring patterns 22 to 25 and the first and second fixed electrodes 9a through the openings 29a to 29d and 31a to 31d and the anchor portions of the fixed electrodes.
-9d, 11a-11d, 13a-13d, 15a-1
5d was electrically connected. Thus, the insulating film is disposed on the upper surface of the substrate 1 and the thin film wiring patterns 22 to
25, the first energizing line for fixed electrode and the energizing line for second fixed electrode can be crossed using the wiring patterns 22 to 25.

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

Further, a laminate 21 of a lower insulating thin film 18, a conductive thin film 19, and an upper insulating thin film 20 is disposed 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.
(Fixed electrode for canceling electrostatic force) 26 is formed, and openings 29 a to 29 in upper insulating thin film 20 are formed.
d, 31a to 31d and the first and second fixed electrodes 10a to 10d and 12a to 12d through the first and second fixed electrodes.
The wiring patterns 22 to 25 of the second fixed electrode and the first and second
Fixed electrodes 9a-9d, 11a-11d, 13a-13
and the lower electrode 26 and the beam structure 2 through the opening 33 in the upper insulating thin film 20 and the anchor portions 3a to 3d of the beam structure.
And were electrically connected. Thus, the insulating film is disposed on the upper surface of the substrate 1 and the thin film wiring patterns 22 to 2 are placed therein.
5 and the lower electrode 26 are buried so that the first fixed electrode energizing line and the second fixed electrode energizing line can intersect using this wiring pattern, and the beam structure (movable part) and the lower electrode Can be set to the same 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) The reliability of the beam structure can be increased because single-crystal silicon, which is a brittle material and has known physical properties such as Young's modulus, is used as the material of the beam structure 2.

(E) By using a polysilicon thin film as the conductive thin film 19 and separating the periphery with an insulator thin film,
The influence of a leak current in a high temperature region as in the case of pn junction isolation can be further reduced.

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

As an application example of this embodiment, in the above-described example, the conductive thin films 19 are used to form the wiring patterns 22 and 24 of the first fixed electrode and the wiring patterns 23 and 23 of the second fixed electrode.
25, but only one of the conductive thin films 1
9, the other may be electrically connected by aluminum wiring or may be electrically connected as a comb-shaped electrode. Further, in the above-described example, the wiring pattern of the fixed electrode and the lower electrode are formed of a buried conductive thin film, but 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 differences from the first embodiment.

FIGS. 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 thereafter 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 region of the above. Here, an impurity is introduced by phosphorus diffusion or the like in order to form an electrode for detecting the capacitance later. Thereafter, as shown in FIG. 18, a silicon oxide film 62 as a thin film for a sacrificial layer 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. Become

Further, as shown in FIG. 19, a recess 63 is formed by partially etching the silicon oxide film 62 through photolithography. 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 sacrificial layer etching step. Further, a silicon nitride film (first insulator thin film) 64 is formed to serve as an etching stopper for etching the sacrificial layer in order to increase surface irregularities. Then, openings 65a, 65b, and 65c are formed in the anchor portion forming region by dry etching or the like through photolithography on the stacked body of the silicon nitride film 64 and the silicon oxide film 62. The openings 65a to 65c are for connecting the beam structure to the substrate (lower electrode), and for connecting the fixed electrode (and the electrode extraction portion) to the wiring pattern.

Subsequently, as shown in FIG.
A polysilicon thin film 66 is formed on the silicon nitride film 64 including 5a to 65c, then impurities are introduced by phosphorus diffusion or the like, and the wiring pattern 66a, the lower electrode 66b, and the anchor portion 66c are formed through photolithography. Form. Thus, an 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 1-2 μm.

This step (the silicon nitride film 6 including the opening)
In a predetermined region on the substrate 4, an impurity-doped polysilicon thin film 66 is formed.
), The polysilicon thin film 66 is thin enough to satisfy the lower pattern resolution of the stepper (1 to 1).
2 μm), the shapes of the openings 65 a to 65 d of the silicon nitride film 64 below 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.
Then, a polysilicon thin film 68 as a bonding thin film is formed thereon, and the surface of the polysilicon thin film 68 is flattened by mechanical polishing or the like for bonding.

Next, as shown in FIG. 23, a single-crystal silicon substrate (support 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 a second semiconductor substrate are prepared. And stick them together.

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

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 via photolithography. The silicon nitride film 7 is formed in a predetermined region on the interlayer insulating film 70.
7 is formed.

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

Finally, as shown in FIG. 27, the silicon oxide film 62 is removed by etching with an HF-based etchant 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 etchant, so that the silicon substrate 60 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 (the step of removing the silicon oxide film 62 in a predetermined area by sacrifice layer etching using an etchant to make the silicon substrate 60 a movable structure)
The anchor portion 66c of the movable portion is made of a conductive thin film, and the etching stops at the anchor portion 66c, so that there is no variation. That is, in this example in which a silicon oxide film is used as a thin film for a sacrificial layer and a polysilicon thin film is used as a conductive thin film, when an HF-based etchant is used, the silicon oxide film is dissolved in HF but the polysilicon thin film is used. Since it does not dissolve, it is not necessary to accurately control the concentration and temperature of the HF-based etchant or to perform the end of the etching with precise time management, and the manufacturing becomes easy.

As described above, since the anchor can be formed, it is not necessary to control the end point by time control in the sacrificial layer etching step when releasing the beam structure, and it is possible to easily control the spring constant and the like. Become.

As described above, the servo control type acceleration sensor can be formed by using the buried SOI substrate and forming the wiring pattern and the lower electrode by insulator separation.

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

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

In this way, when compressive stress remains in the film, it is possible to avoid buckling of the beam due to the effect of the residual stress of the film used for the beam structure 2. Further, when the tensile stress remains in the film, it is possible to prevent the spring constant of the beam from deviating from the design value. As a result, a sensor as designed can be formed.

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

In the present embodiment, the present invention is applied to an excitation type yaw rate sensor. More specifically, two beam structures (movable structures) are provided, and both beam structures (movable structures) are set in opposite phases. And to perform differential detection.

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

In FIG. 30, a beam structure 8 made of single crystal silicon (single crystal semiconductor material) is formed on the upper surface of a substrate 80.
1 and a beam structure 82 (see FIG. 29) are arranged adjacent to each other. The beam structure 81 projects from the substrate 80 side.
The two anchor portions 83 a, 83 b, 83 c, and 83 d are provided, and are disposed at predetermined intervals on the upper surface of the substrate 80. Anchor parts 83a to 83d
Consists of a polysilicon thin film. A beam portion 84 is erected between the anchor portion 83a and the anchor portion 83c,
Beam 85 between anchor 83b and anchor 83d
Has been erected. A rectangular mass part (mass part) 86 is provided between the beam part 84 and the beam part 85. The mass part 86 is provided with a through hole 86a penetrating vertically. Further, a large number of movable electrodes 8 for excitation are
7 are protruding. Each of the movable electrodes 87 has a rod shape,
They extend in parallel at equal intervals. Also, a large number of excitation movable electrodes 88 protrude from the other side surface (the right side surface in FIG. 29) of the mass portion 86. Each of the movable electrodes 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,
Reference numeral 88 is movable by etching and removing a part of the sacrifice layer oxide film 89. This etched area is shown in FIG.
9 and Z2.

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

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

In this embodiment, the comb electrode 90 constitutes a first excitation fixed electrode, and the comb electrode 91 constitutes a second excitation fixed electrode. As shown in FIG. 29, a lower electrode (a yaw rate detecting yaw rate detecting yaw rate detecting yaw rate detecting yaw rate detecting yaw rate detecting fixed electrode) is provided in a region facing a part (mainly the mass portion 86) of the beam structure 81 on the upper surface of the substrate 80. (Fixed electrode) 101 is disposed. Similarly, a lower electrode (a fixed electrode for detecting a yaw rate) 102 as a fixed electrode for detecting a physical quantity is disposed in a region facing a part (mainly the mass portion 86) of the beam structure 82 on the upper surface of the substrate 80. Have been. A first capacitor is provided between the beam structure 81 and the lower electrode 101,
Also, 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 the movable electrode 8 of the beam structure 81
The beam structure 81 can be forcibly vibrated (excited) by applying a reverse-phase electrostatic force between the electrode 8 and the comb electrode 91. Also, the movable electrode 87 and the comb electrode 91 of the beam structure 82
, And between the movable electrode 88 of the beam structure 82 and the comb-teeth electrode 92, the beam structure 82 can be forcibly vibrated (excited). Further, during this excitation, the yaw rate acting on the beam structures 81, 82 is detected based on the capacitance (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 thin 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, the laminated body 100 of the lower insulating thin 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. 97 and 99 are embedded. The lower insulator thin film 97 is made of a silicon oxide film, and the upper insulator thin film 9 is formed.
Reference numeral 9 denotes a silicon nitride film formed by a 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 lower electrodes (fixed electrodes for detecting yaw rate) 101 and 102 and wiring patterns 103 and 104 shown in FIG. or,
As shown in FIGS. 29 and 31, electrode extraction portions 105 and 106 made of single crystal silicon are formed on the upper surface of the substrate 80, and the electrode extraction portions 105 and 106 are supported by anchor portions 107 and 108 projecting from the substrate 80. Have been. In the present embodiment, the electrical connection members are configured by the electrode extraction portions 105 and 106.

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

Note that, as shown in FIG.
Anchors 93, 94, 95 of 91, 92 and anchors 83a, 83b, 83c, 8 of beam structures 81, 82.
Also in 3d, the buried 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 technology.

On the other hand, as shown in FIG.
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. 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. Note that an interlayer insulating film 118 and a silicon nitride film 117 are formed on the electrode extraction portions 105 and 106.

The lower electrode 1 separated from the insulator as described above
By using the wiring patterns 103 and 104, the aluminum electrodes (bonding pads) 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 electrode (fixed electrode for excitation)
A voltage is applied between 90, 91, 92 and the movable electrodes 87, 88 for excitation. Thereby, the mass portion 86 of the beam structures 81 and 82 is vibrated in a direction parallel to the surface of the substrate (Y direction in FIG. 29). At this time, when the yaw Ω is generated in a direction parallel to the surface of the substrate and in a direction perpendicular to the vibration direction (Y direction), the mass portion 86 of the beam structures 81 and 82 is directed in a direction perpendicular to the surface of the substrate. (See FIG. 29). The displacement of the mass portions 86 of the beam structures 81 and 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 82, the mass m of the mass 86, the speed of vibration V, and the yaw Ω, and is expressed by the following equation.

Fc = 2 mVΩ (1) Beam structures 81 and 8 in vibration in a direction parallel to the substrate surface
Since the velocity of the mass portion 86 of the second part is “0” at the fixed end and becomes maximum at the center, the Coriolis force is also the same, and the displacement in the direction perpendicular to the surface of the substrate is “0” at the fixed end as shown in FIG. 0 ", which is maximum at the center, and the mass portion 86 of the beam structures 81, 82 draws an ellipse. Here, the mass portions 86 of the beam structures 81 and 82 (that is, the two mass portions 86) shift the phase of the vibration by 180 degrees, so that the displacement directions are reversed and differential detection becomes possible. If the mass portions 86 of the beam structures 81 and 82 are single (unless the differential excitation is performed), the Coriolis force and the acceleration due to vibration or the like cannot be separated, but the noise component due to the acceleration can be canceled by performing the differential detection. . Generally, the Coriolis force is very small, so that the resonance effect is used. Specifically, in order to increase the velocity V shown in the expression (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 to the resonance frequency to increase the amplitude.
Here, since the Coriolis force is generated in the same cycle as the vibration, if the direction of detection (perpendicular to the surface of the substrate) is also set to the same resonance frequency as the excitation, the displacement due to the Coriolis force can be increased.

Here, as shown in FIG. 33, one of the capacitances is "C" due to the gap change due to the Coriolis force.
o + ΔC ”and the other“ Co−ΔC ”,
If the change in the gap 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 Ω∝2ΔC, and the yaw is detected from the change in the two capacitances. be able to.

The method of manufacturing the yaw rate sensor can be made in the same manner as in the first and second embodiments. As described above, this embodiment has the following features.

On the upper surface of the substrate 80, the lower insulating thin film 9 is formed.
7, a conductive thin film 98, and a laminated body 100 of an upper insulating thin film 99 are arranged, and the conductive thin film 98 forms a lower electrode (fixed electrode for physical quantity detection) 101 (102) and a wiring pattern 103 (104) of the lower electrode. ) Is formed, and the wiring pattern 103 is formed through the opening 109 in the upper insulating thin film 99.
The lower electrode 101 (102) is connected to the substrate 8 through (104).
Electrode take-out part (electrical connection member) 105 (106) above zero
Was electrically connected. In this way, by arranging the insulating film on the upper surface of the substrate 80 and embedding the lower electrode of the thin film (fixed electrode for detecting the physical quantity) and the wiring pattern in the insulating film, it is possible to form the wiring or the electrode by the insulator separation. 48, the junction leakage can be reduced as compared with the case where the impurity diffusion layer 161 shown in FIG. In particular, it is possible to reduce junction leakage in a high temperature range.

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

The present invention is not limited to the above embodiments. For example, in the above embodiment, the acceleration was detected by using the electrostatic servo system. Although detection is performed by applying an electrostatic force that does not cause displacement, the sensor may be embodied as a sensor that directly detects displacement as a change in capacitance.

The present invention can be embodied as 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 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 the line III-III in FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is a sectional view taken along line VV of FIG. 1;

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

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

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

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

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

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

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

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

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

FIG. 19 is a 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 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 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 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 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 a yaw rate sensor according to a fourth embodiment.

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

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

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

FIG. 33 is a 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 in FIG. 34.

FIG. 37 is a cross-sectional view illustrating a method for manufacturing a conventional acceleration sensor.

FIG. 38 is a cross-sectional view illustrating a method for manufacturing a conventional acceleration sensor.

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

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

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

FIG. 42 is a sectional view showing a method for manufacturing a conventional acceleration sensor.

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

FIG. 44 is a sectional view showing a method for manufacturing a conventional acceleration sensor.

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

FIG. 46 is a sectional view showing a method for manufacturing a conventional acceleration sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... beam structure as an electrical 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 part, 11a, 11b, 11c, 11d ... second fixed electrode, 12a, 12b, 12c, 12d ... anchor part, 13a, 13b, 13c, 13d ... first fixed electrode 14a, 14b, 14c, 14d: anchor portion, 15a, 15b, 15c, 15d: second fixed electrode, 16a, 16b, 16c, 16d: anchor portion, 17: silicon substrate as a semiconductor substrate, 18: lower layer side Insulating thin film, 19: conductive thin film, 20: upper insulating thin film, 21: laminated body, 22, 23, 24, 25: wiring pattern, 26: static electricity canceling fixed electrode Lower electrode 27a, 27b, 27c, 27d... Electrode extraction portions as electrical connection members, 29a, 29b, 29c, 29d... Opening, 31a, 31b, 31c, 31d... Opening, 32. .., An opening, 40, a single-crystal silicon substrate as a first semiconductor substrate, 41, a silicon oxide film as a sacrificial layer thin film, 43, a silicon nitride film as a first insulator thin film, 44a, 44b, 44c, 44d: opening, 45: polysilicon thin film as a conductive thin film, 46: silicon oxide film as a second insulating thin film, 46: polysilicon thin film as a bonding thin film, 48: second semiconductor substrate A single-crystal silicon substrate; 49, a groove pattern (groove); 60, a silicon substrate as a first semiconductor substrate; 61, a groove pattern (groove); 62, a sacrifice layer A silicon oxide film as a thin film, 64 a silicon nitride film as a first insulator thin film, 65a, 65b, 65c an opening, 66 a polysilicon thin film as a conductive thin film, 67 a second insulator thin film 68 a polysilicon thin film as a bonding thin film; 69 a single-crystal silicon substrate as a second semiconductor substrate; 80 a substrate; 81 a beam structure; 82 a beam structure; A movable electrode for excitation as the first movable electrode; 88, a movable electrode for excitation as the second movable electrode; 90, a comb-shaped electrode as the first fixed electrode for excitation; 91, a second fixed electrode for excitation; 97: Lower insulating thin film, 98: Conductive thin film, 99: Upper insulating thin film, 100: Laminate, 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.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yukihiro Takeuchi 1-1-1 Showa-cho, Kariya-shi, Aichi F-Term in Denso Co., Ltd. (Reference) 2G064 AB02 BA02 BA07 BB03 BB64 BD05 BD30 BD45 BD47 BD68 BD76 4M112 AA02 BA07 CA21 CA26 CA31 CA33 DA04 DA06 DA12 DA18 EA04 EA06 EA07 EA10 EA11 FA20

Claims (2)

[Claims] 1. A substrate, a beam structure made of a semiconductor material, disposed at a predetermined interval on an upper surface of the substrate, and receiving an acting force displaced by a physical quantity, fixed to the upper surface of the substrate, A semiconductor physical quantity sensor comprising: a fixed electrode disposed so as to face at least a part of the beam structure; and a top surface portion of the substrate and a portion corresponding to a lower portion of the beam structure. And a projection formed on the semiconductor dynamic quantity sensor. 2. The semiconductor physical quantity sensor according to claim 1, wherein the beam structure is made of single crystal silicon.