JPH0850022A - Angular velocity sensor - Google Patents

Abstract

PURPOSE:To highly accurately detect an angular velocity by incorporating an FET in an angular velocity sensor and detecting a shift of a vibrating plate due to a Coriolis force as a drain current flowing in a channel. CONSTITUTION:A substrate 12 is formed of a P-type silicon. A movable part 13 is constituted of a vibrating plate 16 supported via a supporting part and a supporting beam. Tone vibrating plate 16 can vibrate in lateral directions A1 and A2. The vibrating plate 16 is formed as a gate G and, a source area 20 and a drain area 21 are formed to be an N-type semiconductor in the substrate 12. An insulating film 22 is formed on an upper side of the substrate. A shift of a distance between the vibrating plate 16 and the substrate 12 by Coriolis forces F1 and F2 is detected by an insulating gate-type N-channel FET in an angular velocity sensor 11 as a change of a drain current in a channel 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor for detecting the angular velocity of a rotating body, and more particularly to an angular velocity sensor having a field effect transistor built into the sensor.

[0002]

2. Description of the Related Art First, FIGS. 13 to 16 show a conventional angular velocity sensor.

In the figure, 1 is an angular velocity sensor according to the prior art,
Reference numerals 2 respectively denote substrates formed in a rectangular plate shape by a single crystal silicon material having high resistance so as to form the main body of the angular velocity sensor 1.

Reference numeral 3 denotes a movable portion formed on the substrate 2 by low-resistance polysilicon doped with P, B, Sb, etc., and the movable portion 3 faces the longitudinal direction and has a nitride film 4A.
A pair of support portions 4 and 4 provided via the support portions 4 and four support beams 5, 5, ... Which extend in the longitudinal direction (Y-axis direction) from both ends of each support portion 4 toward the central portion. The vibrating plate 6 supported by each of the supporting beams 5, and a plurality of electrode plates 7A, 7A, ... On both left and right side faces of the vibrating plate 6 in the X-axis direction.
Movable-side comb-shaped electrodes 7, 7 made of (five) are formed to project. Further, only each supporting portion 4 is fixed to the substrate 2,
The support beams 5 and the diaphragm 6 are held in a state of being floated from the substrate 2, and the diaphragm 6 is indicated by an arrow A1 so as to be parallel to the substrate 2.
, A2 lateral vibration is generated.

Reference numerals 8 and 8 denote a pair of fixed-side comb-shaped electrodes 8 provided on the substrate 2 so as to sandwich the diaphragm 6 with a nitride film 8A in between, and each fixed-side comb-shaped electrode 8 is the movable-side comb. Electrode plates 8B, 8B, ... (five) on the surface facing the strip electrodes 7,7
Are formed to project.

Reference numerals 9 and 9 denote vibration generating portions which serve as vibration generating means. Each of the vibration generating portions 9 is composed of a movable side comb-shaped electrode 7 and a fixed side comb-shaped electrode 8. The electrodes 7 and 8 are electrodes. Board 7
A gap is formed between A and 8B. Here, when a vibration drive signal of frequency f is applied between the movable side comb-shaped electrode 7 and each fixed side comb-shaped electrode 8, the respective electrode plates 7A, 8B
An electrostatic force is generated between them, and this electrostatic force causes the vibrating plate 6 to alternately vibrate in the direction of arrows A1 and A2 in the same direction and in the horizontal direction with the substrate 2.

Reference numeral 10 denotes a detection electrode plate which constitutes a displacement detection means. The detection electrode plate 10 is a dopant having a characteristic different from that of the substrate 2 on the substrate 2 (for example, if the substrate 2 is a P type, it is an N type). It is formed by high-concentration doping (dopant). The displacement of the space between the diaphragm 6 and the substrate 2 is detected as a change in the electrostatic capacitance between the detection electrode plate 10 and the diaphragm 6.

In the angular velocity sensor 1 thus constructed, when a vibration drive signal is applied to each vibration generating section 9,
The vibrating plate 6 alternately vibrates in the horizontal direction with respect to the substrate 2 with the same magnitude in the directions A1 and A2, and Y in this state.
When the angular velocity Ω is applied around the axis, Coriolis forces (inertial forces) F1 and F2 are alternately generated in the opposite height directions.

Here, the horizontal displacement x and the velocity V of the vibration plate 6 by each vibration generating unit 9 are given by the following equation 1.

[0010]

X = Asin ((2πf) t) V = A (2πf) cos ((2πf) t) where A: amplitude f: frequency of vibration drive signal

Further, the Coriolis forces F1 and F2 are given by the equation 2.

[0012]

## EQU2 ## F1 = F2 = 2 mΩV = 2 mΩ × A (2πf) cos ((2πf) t) where m: mass of diaphragm 6

Then, as shown in FIGS. 13 and 15, the diaphragm 6 vibrates up and down by the force of the equation 2, and the diaphragm 6
The vibration displacement due to is detected as a change in capacitance between the detection electrode plate 10 and the vibration plate 6, and the angular velocity Ω is detected.

[0014]

By the way, the angular velocity sensor 1 according to the above-mentioned conventional technique is manufactured by using the semiconductor manufacturing technique of silicon (so-called micromachining technique such as film formation and etching). When the angular velocity sensor 1 is created by utilizing it, the mass and size of the diaphragm 6 of the movable portion 3 are reduced. Further, as is clear from the above equation 2, since the Coriolis forces F1 and F2 depend on the mass m of the diaphragm 6, the Coriolis force acting on the diaphragm 6 becomes small. As a result, the displacement of the diaphragm 6 in the height direction becomes small, and the output signal becomes minute, so that the angular velocity Ω cannot be detected with high accuracy.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention provides an angular velocity sensor capable of highly accurately detecting an angular velocity by configuring the displacement detecting means as a field effect transistor. Is intended.

[0016]

In order to solve the above-mentioned problems, the structure of the angular velocity sensor adopted in the invention of claim 1 is such that a semiconductor substrate and a supporting beam are provided on a supporting portion provided on the substrate. A movable part having a diaphragm supported via the vibration part, vibration generating means for applying a vibration of the movable part in the horizontal direction to the substrate, and a state in which the vibration generating means vibrates the diaphragm. And a displacement detecting means for detecting the displacement of the vibrating plate in the vertical direction due to the Coriolis force, and the vibrating plate of the movable part is used as a gate, and the vibrating plate is separated from the surface of the substrate facing the vibrating plate. By forming the source and the drain, the displacement detecting means is configured as a field effect transistor including a gate, a source and a drain.

According to a second aspect of the present invention, the substrate is formed of a P-type semiconductor, the source and the drain are formed of an N-type semiconductor, and the displacement detecting means is an N-channel insulated gate field effect transistor. is there.

According to a third aspect of the present invention, the substrate is made of an N-type semiconductor, the source and drain are made of a P-type semiconductor, and the displacement detecting means is a P-channel insulated gate field effect transistor. is there.

Further, the invention of claim 4 is that the substrate is made of a silicon material, and the movable portion is made of a polysilicon material.

Further, the invention of claim 5 is the source,
The drain is connected to the outside via electrodes provided on the substrate, and the gate is connected to the outside via electrodes provided on the supporting portion of the movable portion.

[0021]

According to the invention of claim 1, the diaphragm of the movable part is formed as a gate, the source and the drain are formed separately on the surface of the substrate facing the diaphragm, and the displacement detecting means is a field effect transistor. As a result, the distance between the diaphragm and the substrate, which is displaced by the Coriolis force, causes a change in capacitance, and this change in capacitance is a field (channel) formed between the source and drain for the field effect transistor. Influences the current flowing through the drain and controls the drain current flowing through the channel. Then, this change in the drain current can be detected as a displacement corresponding to the distance between the diaphragm and the substrate.

According to a second aspect of the present invention, in the insulated gate field effect transistor, the substrate is made of a P-type semiconductor (N-type semiconductor), and the source and the drain are N-type semiconductor (P-type).
, A source-drain passage (channel) can be configured as an N-channel (P-channel) insulated gate field effect transistor serving as an electron passage.

Further, as in claim 4, the substrate is made of a silicon material and the movable portion is made of a polysilicon material, whereby the movable portion formed on the substrate can be easily formed.

Further, since the source and the drain are connected to the outside via the electrode provided on the substrate and the gate is connected to the outside via the electrode formed on the supporting portion of the movable portion, The connection with the outside can be easily performed, and each electrode can be easily formed by patterning or the like.

[0025]

Embodiments of the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

First, FIGS. 1 to 8 show a first embodiment of the present invention.

In the figure, reference numeral 11 denotes an angular velocity sensor according to this embodiment, and although the angular velocity sensor 11 has substantially the same structure as the angular velocity sensor 1 according to the prior art, the angular velocity sensor 11 has a gate on a movable portion 13 described later. G, by forming the source region 20 and the drain region 21 on the surface of the substrate 12, respectively, the field effect transistor 27 (hereinafter,
(Referred to as FET 27).

Reference numeral 12 denotes a rectangular plate-shaped substrate which constitutes the body of the angular velocity sensor 11, and the substrate 12 is formed by doping a pure single crystal silicon material with trivalent atoms such as B, Al, Ga and In. Formed as a semiconductor.

Reference numeral 13 denotes a movable portion formed on the substrate 12 by low-resistance polysilicon doped with P, B, Sb, etc. The movable portion 13 faces the longitudinal direction of the substrate 12 and has a nitride film. 14A, a pair of support portions 14 and 14 provided therebetween, four support beams 15 extending from both ends of each support portion 14 in the longitudinal direction, and the support beams 1
And a diaphragm 16 supported by 5. In addition, a plurality of electrode plates 17A,
Movable side comb-shaped electrodes 17 and 1 composed of 17A, ... (5 pieces)
7 is formed so as to project.

As described above, in the movable portion 13,
Only the supporting portions 14 are fixed to the substrate 12 via the nitride film 14A, and the supporting beams 15 and the vibrating plate 16 are held in a state of floating from the substrate 12. The vibrating plate 16 is adapted to generate lateral vibration in the directions A1 and A2 so as to be parallel to the substrate 12. The diaphragm 16 of the movable portion 13 serves as a gate G forming the FET 27.

Reference numerals 18 and 18 denote a pair of fixed-side comb-shaped electrodes provided on the substrate 12 via a nitride film 18A. The fixed-side comb-shaped electrodes 18 are made of polysilicon and are in the X-axis direction. The electrode plates 17 of the movable-side comb-shaped electrodes 17 are provided separately on both the left and right sides of the vibration plate 16 and are separated from each other.
The electrode plate 18 is provided on the surface facing A, 17A ,.
B, 18B, ... (5) are formed so as to project.

Reference numerals 19 and 19 denote vibration generators serving as vibration generators, and each of the vibration generators 19 is a movable-side comb-shaped electrode 17.
And the fixed side comb-shaped electrode 18,
A gap is formed between the 18 electrode plates 17A and 18B. Here, when a vibration drive signal of frequency f is applied between the movable side comb-shaped electrode 17 and each fixed side comb-shaped electrode 18, an electrostatic force is generated between the electrode plates 17A and 18B, and this electrostatic force causes The vibrating plate 16 alternately vibrates in the horizontal direction with the substrate 12 with the same magnitude in the directions A1 and A2.

Reference numeral 20 denotes a source region according to the present embodiment, and 21 denotes a drain region according to the present embodiment. The source region 20 and the drain region 21 are longitudinally located on the surface of the substrate 12 facing the diaphragm 16. The regions 20 and 21 are formed as N-type semiconductors by ion-implanting the substrate 12 with pentavalent atoms such as P, As and Sb.

Reference numeral 22 denotes an insulating film, which is formed of a nitride film on the surface of the substrate 12 facing the vibrating plate 16, and the insulating film 22 extends over the source region 20 and the drain region 21. The size is large.

Reference numeral 23 denotes a source-side electrode pattern formed of chromium-platinum-gold, chromium-gold or the like, and the electrode pattern 23 is formed on the substrate 12 so as to avoid the movable portion 13. The electrode pattern 23 connects the source region 20 and the source-side electrode pad 23A provided at the end of the substrate 12 in the longitudinal direction.

24 is also chromium-platinum-gold, chromium-
Shows a drain side electrode pattern formed of gold or the like,
The electrode pattern 24 is formed on the substrate 1 so as to avoid the movable portion 13.
It is formed on 2. The electrode pattern 24 connects the drain region 21 and the drain-side electrode pad 24A provided on the end of the substrate 12 in the longitudinal direction.

Reference numeral 25 denotes a gate-side electrode pad formed of chromium-platinum-gold, chromium-gold, or the like, and the gate-side electrode pad 25 is provided on one support portion 14 of the movable portion 13.

Reference numeral 26 denotes an electrode plate formed on the back surface side of the substrate 12 by an aluminum thin film or the like.

As described above, in the angular velocity sensor 11 according to this embodiment, the vibrating plate 16 of the movable portion 13 is used as the gate G, and the source region 20 and the drain region 21 are separated from each other on the surface of the substrate 12 facing the vibrating plate 16. The source region 2
Since the insulating film 22 made of a nitride film is formed between 0 and the drain region 21, an insulated gate FET 27 (see FIG. 8) is formed in the angular velocity sensor 11 as a displacement detecting means.

Further, the substrate 12 is formed of a silicon plate which becomes a P-type semiconductor, and the source region 20 and the drain region 21 are formed as N-type semiconductors, so that an inversion layer is formed immediately below the insulating film 22 of the substrate 12. An electron passage (hereinafter, referred to as channel 28 (see FIG. 2)) is formed. Since the channel 28 is an N-type channel in this embodiment, the FET 27 is configured as an N-channel field effect transistor.

Next, a method of manufacturing the angular velocity sensor 11 having the above structure will be described with reference to FIGS.

Here, in the preliminary step shown in FIG. 4, an N-type semiconductor is obtained by ion-implanting pentavalent atoms such as P, As, and Sb at a predetermined position on the surface of the silicon wafer 31 formed on the P-type semiconductor. Source region 20 and drain region 2
1 is formed. Further, the nitride films 14A and 14A are formed at the positions where the supporting portions 14 and 14 are formed on the surface of the silicon wafer 31.
A is deposited to form the source region 20 and the drain region 21.
The insulating film 22 is formed at a position straddling the above.

Next, in the polysilicon layer forming step shown in FIG. 5, a sacrifice layer 32 made of a phosphorus-doped oxide film (PSG film) is formed between the nitride films 14A and 14A, and a polysilicon layer is formed thereon. Form the layer 33.

Further, in the etching step for forming the movable portion 13 and the fixed side comb-shaped electrodes 18, 18 shown in FIG. 6, Al is formed from the outside of the polysilicon layer 33 by photolithography.
After patterning a mask such as a film, a SiO ₂ film, a resist, etc., the movable part 13 and the fixed side comb-shaped electrodes 18, 18 are etched by etching such as RIE (Reactive Ion Etching).
To form. At this time, each electrode plate 17A of each movable-side comb-shaped electrode 17 is formed on the diaphragm 16, and each electrode plate 18B is formed on the fixed-side comb-shaped electrode 18, so that both sides of the diaphragm 16 are formed. The vibration generators 19, 19 are configured. Further, by depositing and patterning chromium-platinum-gold, chromium-gold, etc., the source region 2
0, an electrode pattern 23 connected to the drain region 21,
24, electrode pads 23A, 24A, 25 are formed.

Then, in the sacrifice layer removing step shown in FIG.
The sacrificial layer 32 is removed by wet etching with an HF solution or the like, and a large number of angular velocity sensors 11 are manufactured from one silicon wafer 31 by dicing at the position shown by the dotted line in FIG.

Thus, the angular velocity sensor 1 according to this embodiment is
1 is configured, the circuit diagram for detecting the angular velocity Ω is shown in FIG. 8 and the detection operation of the angular velocity sensor 11 will be described.

The configuration of the entire circuit in FIG.
27, the source grounding system is used, and the voltage VGS for applying a potential to the gate G and the voltage VDS for applying a potential between the source S and the drain D are connected to predetermined polarities.

Reference numeral 41 denotes a detection resistor connected to the drain D side of the FET 27, and the detection resistor 41 is the FET 2
The drain current Id flowing through the No. 7 channel 28 is detected as a voltage.

Reference numeral 42 designates an amplifier circuit which is located after the detection resistor 41 and is connected via a coupling capacitor 43. The amplification circuit 42 amplifies a voltage corresponding to the drain current Id detected by the detection resistor 41. To do.

Here, the angular velocity sensor 11 according to the present embodiment.
The mechanical operation in A is similar to that of the angular velocity sensor 1 of the related art, and the diaphragm 16 is indicated by an arrow A by a vibration drive signal.
When angular velocity Ω is applied around the Y-axis while vibrating in the horizontal direction with respect to the substrate 12 in the 1 and A2 directions, the Coriolis forces (inertial forces) F1 and F2 act alternately in the opposite height directions. However, the diaphragm 16 vibrates up and down.

Next, in the electrical operation, the diaphragm 1
Since 6 is the gate G of the FET 27, the capacitance due to the distance between the diaphragm 16 and the substrate 12 changes the capacitance between the gate G and the channel 28. Then, this capacitance has a great influence on the drain current Id flowing through the channel 28.

Since the voltage VGS applied to the gate G is constant, the amount of charges induced by the electric field effect in the channel 28 depends on the electrostatic capacitance between the gate G and the channel 28. become. That is, the diaphragm 16
Becomes close to the substrate 12, the capacitance increases,
The amount of charges induced in the channel 28 increases, the resistance value of the channel 28 decreases, and the drain current Id increases.
Grows. On the other hand, when the vibrating plate 16 is separated from the substrate 12, the capacitance becomes small, the amount of charges induced in the channel 28 decreases, the resistance value of the channel 28 becomes large, and the drain current Id becomes small.

Since the drain current Id detected by the detection resistor 41 is amplified and output by the amplifier circuit 42, the displacement of the diaphragm 16 due to the Coriolis forces F1 and F2 applied to the diaphragm 16 is detected with high accuracy. can do.

The portion of the electrostatic capacitance generated by the distance between the diaphragm 16 and the substrate 12 is taken as the gate, drain,
It is provided between the sources, and the change in capacitance is directly reflected by the FET 27.
Since it is detected as a change in the drain current Id, it is possible to prevent noise from being superposed, so that a minute change in the capacitance can be accurately detected as a large change in the drain current Id.

As described above, in the angular velocity sensor 11 according to the present embodiment, by forming the FET 27 in the angular velocity sensor 11, the angular velocity Ω applied around the Y axis acts on the Coriolis forces F1 and F2 acting above and below the diaphragm 16. The vertical vibration of the diaphragm 16 can be directly detected as the amount of charges induced in the channel 28, and is detected as the change of the drain current Id. And FET2
Since 7 is integrated with the element, the diaphragm 16 and the substrate 1
It is possible to detect a displacement of a minute distance from 2 as a signal having a good S / N ratio without being affected by noise from the outside. As a result, even if the mass and size of the diaphragm are small, this displacement can be accurately detected, and the angular velocity Ω
Can be detected with high accuracy.

Further, in this embodiment, the substrate 12 is made of single crystal silicon, and the movable portion 13 and each of the fixed side comb-shaped electrodes 18 are formed.
The movable part 1 is formed by forming the
3 and each fixed-side comb-shaped electrode 18 can be easily formed, and the productivity of the angular velocity sensor 11 can be improved. Furthermore, by simultaneously processing a plurality of angular velocity sensors 11 including the manufacturing steps shown in FIGS. 4 to 7 on a single silicon wafer 31, a large number of angular velocity sensors 11 can be manufactured in one manufacturing step.

Further, a source side electrode pattern 23 for connecting the source region 20 and the outside is formed on the substrate 12, and a drain side electrode pattern 24 for connecting the drain region 21 and the outside is formed on the substrate 12. Further, since the gate-side electrode pad 25 for connecting the gate and the outside is formed on the support portion 14, the source, drain and gate can be easily connected to the outside. Moreover, the electrode patterns 23, 24 and the electrode pad 25 are made of chromium-platinum-
It can be easily formed by patterning gold, chrome-gold or the like on the substrate 12 or the support portion 14.

In the above-mentioned embodiment, the source region 20 and the drain region 21 are connected to the electrode patterns 23 and 2, respectively.
4 is used to electrically connect to the electrode pads 23A and 24A, but the present invention is not limited to this, and may be configured as shown in the modified examples of FIGS. 9 to 11, for example.

That is, the source region 20 and the drain region 21
Low resistance regions 20A and 21A respectively connected from
Except for the contact holes 34A and 34A for exposing a part of each of the low resistance regions 20A and 21A, an insulating film 34 deposited on the surface of the substrate 12 and a contact hole formed on the insulating film 34. 34A, 3
Contact electrodes 35 and 36 electrically connected to the low resistance regions 20A and 21A via 4A, an electrode pattern 23 having an electrode pad 23A electrically connected to the contact electrode 35, and a contact electrode 36. Electrode pattern 24 having electrode pad 24A electrically connected
Composed of and.

The source region 20 is the low resistance region 20.
A, the contact electrode 35, and the electrode pattern 23 are used to electrically connect to the electrode pad 23A.

Further, the drain region 21 is the low resistance region 2
1A, the contact electrode 36, and the electrode pattern 24 are used to electrically connect to the electrode pad 23A.

Further, in this structure, the insulating film 34 is the nitride film 14A, 1 formed between the substrate 12 and the support portion 14.
4A, nitride films 18A, 18A formed between the substrate 12 and the fixed-side comb-shaped electrode 18, and an insulating film 22 formed on the surface of the substrate 12 facing the diaphragm 16. There is.

In this case, the low resistance regions 20A, 2
1A is a source region 20 and a drain region 21 in the preliminary process.
Can be formed by a method similar to the method of forming
Formed by ion-implanting pentavalent atoms such as P, As, and Sb into N-type semiconductors at predetermined positions continuous with the source region 20 and the drain region 21 on the surface of the silicon wafer 31 formed on the semiconductor semiconductor. To be done. Further, the insulating film 34 is formed with, for example, a nitride film on the entire surface of the silicon wafer 31, and then patterned so as to expose a part of each of the low resistance regions 20A and 21A, whereby contact holes 34A and 34A are formed. To be done. Further, the contact electrodes 35, 36, the electrode pattern 23,
24 and the electrode pads 23A and 24A are formed by depositing and patterning chromium-platinum-gold, chromium-gold, or the like on the insulating film 34.

Next, FIG. 12 shows a second embodiment according to the present invention. The feature of this embodiment is that the substrate is made of N-type semiconductor and the source region and the drain region are made of P-type semiconductor. Therefore, the FET 52 of the angular velocity sensor 51 is a P-channel field effect transistor.

Incidentally, the angular velocity sensor 51 according to this embodiment.
Has the same configuration as the angular velocity sensor 11 according to the first embodiment described above, the description thereof will be omitted. In FIG. 12, only a circuit diagram of the P-channel FET 52 is shown.

Therefore, the angular velocity sensor 51 according to this embodiment is
Then, the detecting operation can be performed in substantially the same manner as the angular velocity sensor 11 according to the first embodiment described above.
Further, due to the configuration of the FET 52, as shown in the circuit diagram of FIG. 12, the polarities of the voltage VGS and the voltage VDS are opposite to those of the first embodiment, and the drain current Id flows in the opposite direction. , The first in the detection of angular velocity Ω
Highly accurate detection can be performed as in the embodiment described above.

In each of the above embodiments, the fixed-side comb-shaped electrodes 18 are formed on both sides of the vibration plate 16 in order to laterally vibrate the vibration plate 16, but the present invention is not limited to this. A piezoelectric body (piezo element) is provided on each support beam 15 of the diaphragm 16.
Etc. may be formed so that the piezoelectric body causes lateral vibration.

Although the insulating film 22 is formed of the nitride film in each of the above-mentioned embodiments, it may be formed of an oxide film to form the FETs 27 and 52 as MOS type field effect transistors. Further, the insulating film 22 may be formed of an insulating material such as alumina.

Further, the substrate 12 is not limited to a single crystal silicon plate, but may be formed of germanium or gallium arsenide single crystal.

[0070]

As described in detail above, according to the invention of claim 1, the diaphragm of the movable portion is formed as a gate, and the source and the drain are formed separately on the surface of the substrate facing the diaphragm, respectively.
By using a field effect transistor as the displacement detecting means, the distance between the diaphragm and the substrate displaced by the Coriolis force becomes a change in electrostatic capacitance, and this change in electrostatic capacitance is
As a field effect transistor, it influences carriers flowing in a passage (channel) formed between a source and a drain and controls a drain current flowing in the channel. By directly detecting the displacement of the diaphragm due to the Coriolis force in the field effect transistor, it is possible to eliminate the superposition of noise and to largely change the drain current even when the diaphragm has a small mass and size. Can be detected with high accuracy.

In the invention of claim 2 (3), in the insulated gate field effect transistor, the substrate is formed of a P-type semiconductor (N-type semiconductor), and the source and the drain are formed of an N-type semiconductor (P-type semiconductor). By doing so, the channel between the source and the drain becomes a channel for carriers.
It can be configured as a channel (P-channel) insulated gate field effect transistor, and a drain current flowing through the N-channel (P-channel) can be detected as a displacement of the distance between the diaphragm and the substrate by a source-grounded circuit. Then, the angular velocity can be detected with high accuracy.

According to the present invention, the substrate is made of a silicon material, and the movable portion is made of a polysilicon material. Therefore, the movable portion formed on the substrate can be easily formed, and a field effect transistor is obtained. The productivity of the built-in angular velocity sensor can be improved.

Further, in the present invention, the source and the drain are connected to the outside through the electrode provided on the substrate, and the gate is connected to the outside through the electrode formed on the supporting portion of the movable portion. Therefore, it is possible to easily connect to the outside through each electrode, and each electrode can be easily formed by patterning or the like.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional view as seen from the direction of arrows II-II in FIG.

FIG. 3 is a vertical cross-sectional view as seen from the direction of arrows III-III in FIG.

FIG. 4 is a vertical cross-sectional view showing a state where a source / drain region is formed of an N-type semiconductor and a nitride film and an insulating film are formed on a silicon plate by a method of manufacturing an angular velocity sensor.

FIG. 5 is a vertical cross-sectional view showing a state in which a sacrificial layer and a polysilicon layer are formed on the substrate, following FIG.

FIG. 6 is a vertical sectional view following FIG. 5, showing a state in which a movable portion and a fixed-side comb-shaped electrode are formed by pattern-etching a polysilicon layer.

7 is a vertical cross-sectional view showing the state where the sacrificial layer is removed and an electrode portion is provided, following FIG.

FIG. 8 is a circuit configuration diagram showing a detection circuit using the angular velocity sensor according to the first embodiment.

FIG. 9 is a plan view of an angular velocity sensor according to a modification of the first embodiment at the same position as in FIG.

FIG. 10 is a vertical cross-sectional view as seen from the direction of arrow XX in FIG.

FIG. 11 is a vertical cross-sectional view as seen from the direction of arrow XI-XI in FIG. 9.

FIG. 12 is a circuit configuration diagram showing a detection circuit using an angular velocity sensor according to a second embodiment.

FIG. 13 is a perspective view showing an angular velocity sensor according to a conventional technique.

FIG. 14 is a plan view showing an angular velocity sensor according to a conventional technique.

15 is a vertical cross-sectional view as seen from the direction of arrows XV-XV in FIG.

16 is a vertical cross-sectional view as seen from the direction of arrow XVI-XVI in FIG.

[Explanation of symbols]

 11, 51 Angular velocity sensor 12 Substrate 13 Movable part 14 Support part 15 Support beam 16 Vibrating plate 17 Movable side comb-shaped electrode 18 Fixed side comb-shaped electrode 19 Vibration generating part (vibration generating means) 22 Insulating film 23 Source side electrode pattern 24 Drain Side electrode pattern 25 Gate side electrode pad 27,52 FET (field effect transistor) 28 Channel 31 Silicon wafer 33 Polysilicon layer Ω Angular velocity

Front page continuation (72) Inventor Tomoho Hasegawa 26-10 Tenjin, Nagaokakyo, Kyoto Prefecture Murata Manufacturing Co., Ltd. (72) Inventor Kenichi Atsuji 2-10-10 Tenjin, Nagaokakyo, Kyoto Murata Manufacturing Co., Ltd. (72) Inventor Shoichi Sugimoto 2-10-10 Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd.

Claims (5)

[Claims] 1. A semiconductor substrate, a movable part having a diaphragm supported by a supporting part provided on the substrate via a support beam, and a diaphragm of the movable part in a horizontal direction with respect to the substrate. The movable part includes vibration generating means for giving vibration, and displacement detecting means for detecting a vertical displacement of the diaphragm due to Coriolis force in a state where the diaphragm is vibrated by the vibration generating means. The diaphragm as a gate, and the source in a state of being spaced apart from the surface of the substrate facing the diaphragm,
An angular velocity sensor formed by forming a drain to configure the displacement detecting means as a field effect transistor including a gate, a source and a drain. 2. The angular velocity sensor according to claim 1, wherein the substrate is formed of a P-type semiconductor, the source and the drain are formed of an N-type semiconductor, and the displacement detecting means is an N-channel insulated gate field effect transistor. . 3. The angular velocity sensor according to claim 1, wherein the substrate is made of an N-type semiconductor, the source and the drain are made of a P-type semiconductor, and the displacement detecting means is a P-channel insulated gate field effect transistor. . 4. The angular velocity sensor according to claim 1, wherein the substrate is made of a silicon material, and the movable portion is made of a polysilicon material. 5. The structure in which the source and the drain are connected to the outside via electrodes provided on the substrate, and the gate is connected to the outside via electrodes provided on a supporting portion of the movable portion. The angular velocity sensor according to claim 1, 2, 3, or 4.