JP2002022581A - Semiconductor pressure sensor - Google Patents

Abstract

(57) [Problem] To provide a small-sized semiconductor pressure sensor that does not require an external circuit and does not generate noise in an unnecessary pressure range. A semiconductor pressure sensor includes a pressure switch side substrate on which a pressure switch is formed in advance, and a bridge circuit side substrate on which a bridge circuit having a mesa structure is formed.
02 is formed by laminating each frame portion and the pressure-sensitive resistor portion. The pressure switch side substrate 1001 is made of SO
It can be easily formed from an I (Silicon On Insulator) substrate. The switch conductive silicon part 122 applies the power to the switch pressure-sensitive insulating part 132 and the switch leg insulating layer 112A.
And 112B as fulcrums, switch contact conductors 14A and 14B
Form a double lever structure, which is the point of action. <1-10
Pressure-sensitive resistors 162 and 164 having a longitudinal direction in the
001> pressure-sensitive resistors 161, 16 having a longitudinal direction
3 can be formed on the bridge circuit-side substrate 1002 two by two to form a pressure sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor pressure sensor utilizing a piezoresistance effect. More specifically, the present invention relates to a semiconductor pressure sensor having an on-chip switch function.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional semiconductor pressure sensor 900 utilizing the piezoresistive effect of a diffusion resistor. FIG.
(A), a diaphragm 92 shown by a dotted line is provided on a silicon substrate 91, and two piezo resistors 931 and 933 are provided around the diaphragm 92, and piezo resistors 932 and 934 are provided at the center of the diaphragm 92. Is provided.
A cross-sectional view is shown in FIG. Semiconductor pressure sensor 900
Is that the diaphragm 92 is curved,
1 and 933 increase in resistance and piezoresistors 932 and 934
Decrease in resistance or vice versa. Utilizing this, a pressure sensor can be obtained by forming a bridge circuit using four piezoresistors and applying a constant voltage to two terminals and measuring a potential difference between the remaining two terminals. FIG. 9 (c) shows a state of being mounted on a package. It is packaged so that the upper part of the diaphragm 92 is airtight and the lower part of the diaphragm 92 communicates with the outside. In this way, the pressure difference between the pressure inside the package and the external pressure communicating below the diaphragm 92 can be output as a potential difference.

[0003]

By the way, since the piezoresistor has an extremely high sensitivity, noise is easily picked up. This will reduce the S / N ratio of the pressure sensor. Therefore, it may be necessary to display the pressure only at a certain pressure or higher. FIG. 10 shows a circuit for this purpose. The piezo resistors 931, 932, 933 and 934 are connected in this order. Here, the connection between the piezoresistors 934 and 931 is connected to the electrode 95.
1. The connection between the piezoresistors 931 and 932 is connected to the electrode 952,
The connection between the piezoresistors 932 and 933 is an electrode 953, and the connection between the piezoresistors 933 and 934 is an electrode 954. When a potential is applied between the electrode 951 and the electrode 953 by the constant voltage power supply 941 in this manner, the pressure inside the package and
The pressure difference between the external pressure passing under the diaphragm 92 and the electrode 95
It is output as a potential difference V ₁ of the 2 and the electrode 954. This is determined by the pressure determination circuit 96, and if it is equal to or more than a certain value, the pressure is displayed on the pressure display device 97.

Incidentally, a pressure determination circuit 9 which is an external circuit
6 causes the number of parts to increase, and the pressure sensor 90
The whole device including 0 is large. Also, even in the pressure range where the noise level is unnecessary,
Constant voltage power supply 941 and power supply 942 to pressure determination circuit 96
Power consumption. Further, in the above-described configuration, a precise housing is required for packaging, which hinders miniaturization and cost reduction.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a small-sized semiconductor pressure sensor which does not require an external circuit and does not generate noise in an unnecessary pressure range. .

[0006]

According to the first aspect of the present invention, there is provided a semiconductor pressure sensor having a hermetically sealed structure formed by providing a raised portion on two semiconductor substrates and bonding them together. Wherein a pressure switch is formed such that a circuit is opened at a certain pressure or less and a circuit is closed at a certain pressure or more by providing a conductor portion and a contact in a sealed structure.

According to a second aspect of the present invention, a bridge circuit using a piezoresistor is provided on the semiconductor substrate surface inside the sealed structure, and the bridge circuit has a structure closed by a pressure switch. I do.

According to a third aspect of the present invention, a bridge circuit of a sensing portion having a mesa structure using a piezo resistor is provided on a protruding portion forming a sealed structure, and the bridge circuit is closed by a pressure switch. It is characterized by having a structure. Here, the protruding portion forming the hermetic structure only needs to protrude from the vicinity thereof, and for example, may be a structure higher than the bottom of the trench by a trench (groove).

According to a fourth aspect of the present invention, a short-circuit switch formed to short-circuit a circuit or a bridge circuit by a pressure greater than a pressure at which the pressure switch closes is provided in the sealed structure. I do.

[0010]

Since the semiconductor device has a hermetically sealed structure in which two semiconductor substrates are provided with a raised portion and bonded together, the operation is caused by a pressure difference between the inside of the hermetically sealed structure and the outside applied to the two semiconductor substrates. Forming a semiconductor pressure sensor. At this time, if a conductor part and a contact are provided in the hermetically sealed structure, and the circuit is opened at a certain pressure or less and the circuit is closed at a certain pressure or more, a semiconductor pressure sensor integrated with the pressure switch can be formed. . Since the pressure switch can be integrated with the semiconductor pressure sensor, low power consumption can be realized. In addition, since a sealed structure can be provided, a housing is not required, and the pressure-sensitive portion can be used without a housing even in a non-conductor (claim 1).

As a semiconductor pressure sensor having a sealed structure, a bridge circuit using a piezoresistor is formed on the surface of a semiconductor substrate inside the sealed structure, or a piezoresistor is formed on a raised portion (pressure-sensitive portion) forming the sealed structure. This can be achieved by forming a bridge circuit of the sensing section having the mesa structure used (claims 2 and 3).

Furthermore, if there is a short-circuit switch that short-circuits the circuit when the pressure is equal to or higher than a certain value, the semiconductor pressure sensor can generate an output from the pressure at which the pressure switch closes to the pressure at which the short-circuit switch closes. Therefore, an electric signal of the pressure sensor can be taken out only in an arbitrarily set pressure range (claim 4).

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be exemplified. Note that the present invention is not limited to the following examples.
Modifications such as having a plurality of closed structures or combining structures having different closed structures are naturally included in the present invention. In the following, a semiconductor pressure sensor that operates when the outside is at a higher pressure than the inside of the sealed structure will be described as one that closes the bridge circuit when the outside is at a high pressure. At this time, for example, a configuration may be adopted in which a short circuit is opened and a bridge circuit operates. This is naturally included in the present application. The method of joining the two processed substrates is not limited to anodic bonding but may be any method.

FIG. 1 shows the structure of a semiconductor pressure sensor 1000 according to a first embodiment of the present invention. Figure 1
(A) is a cross-sectional view when the external pressure matches the pressure inside the closed structure, and (b) of FIG. 1 is a cross-sectional view showing the operation when the external pressure is higher than the pressure inside the closed structure.

The semiconductor pressure sensor 1000 includes a pressure switch side substrate 1001 in which a pressure switch is formed in advance and a bridge circuit side substrate 10 in which a mesa structure bridge circuit is formed.
02 is formed by laminating each frame portion and the pressure-sensitive resistor portion. The pressure switch side substrate 1001 is made of SO
It can be easily formed from an I (Silicon On Insulator) substrate, and includes a silicon part 100, an intermediate insulating layer 111, a frame silicon part 121, a frame junction insulating part 131, and a switch structure. Silicon part 100, intermediate insulating layer 11
1. The frame silicon part 121 is formed by etching from an SOI substrate. The frame joining insulating portion 131 is formed by forming Pyrex (registered trademark) glass on the frame silicon portion 121. The switch structure is a silicon part 1
The switch leg insulating layers 112A and 112B, the plate-shaped or beam-shaped switch conductive silicon part 122, the switch pressure-sensitive insulating part 132, and the switch contact conductive parts 14A and 14B
Consists of The switch leg insulating layers 112A and 112B and the switch conductive silicon portion 122 are formed by etching from the SOI substrate. Switch leg insulating layer 112A, 1
To form 12B (leave it during etching),
This can be achieved by forming the switch conductive silicon portion 122 in a lattice having holes (not shown). The switch conductive silicon part 122 is a low resistance layer. The switch contact conductors 14A and 14B are formed of a metal thin film or the like. The switch structure leverages the switch conductive silicon part 122,
The switch pressure-sensitive insulating portion 132 is a point of focus, the switch leg insulating layers 112A and 112B are fulcrums, and the switch contact conducting portion 14A is provided.
And 14B is a double lever structure in which the action points are provided. Note that, in the two cross-sectional views of FIGS. 1A and 1B, only the low-resistance portion is shown using hatching.

The bridge circuit-side substrate 1002 on which a bridge circuit having a mesa structure is formed has an n-type region formed on a p-type silicon substrate or a p-type region formed on an n-type silicon substrate.
The structure is etched, leaving the portion, and the circuit is raised. In the sectional view of FIG.
Pressure-sensitive resistor 1 to be joined to frame 001 of frame 001
61 and 163 are shown, but the frame joint insulating portion 1
The electric resistance changes due to the compressive force together with the set of the pressure-sensitive resistors 162 and 164 joined to 31. The bridge circuit side substrate 1002 includes a switch pressing portion 170 joined to the switch pressure-sensitive insulating portion 132 of the pressure switch side substrate 1001, a switch contact conducting portion 14A,
Contact portions 157A and 158B which are respectively opposed to 4B are formed.

When an external pressure is applied to the semiconductor pressure sensor having the structure shown in FIG. 1A (the external pressure becomes higher than the pressure inside the sealed structure), a vertical compressive force is applied to the pressure-sensitive resistors 161 to 164. And the bridge circuit side substrate 100
When the switch pressing portion 170 pushes the switch pressure-sensitive insulating portion 132 downward through the switch 2, the switch conductive silicon portion 122 bends with the switch leg insulating layers 112A and 112B as fulcrums, and the switch contact conductive portions 14A and 14B are turned. The contact portions 157A and 158B come into contact with each other (FIG. 1B). The pressure at which the contact portion 157A, the switch contact conductive portion 14A, the switch conductive silicon portion 122, the switch contact conductive portion 14B, and the contact portion 158B are conducted can be easily adjusted in the design of the semiconductor pressure sensor 1000. Therefore, by forming a bridge circuit as a main part of the pressure sensor as described below, the semiconductor pressure sensor 1000 can be a semiconductor pressure sensor having a pressure switch that outputs an electric signal only at a certain pressure or higher.

FIG. 2 is a perspective view of the pressure switch side substrate 1001 and the bridge circuit side substrate 1002. FIG. 2A is a perspective view of the pressure switch side substrate 1001,
Except that the frame portion forms a square, it is as already described in the description of FIG. FIG. 2B shows the bridge circuit side substrate 10.
02 is a perspective view of FIG. 02, and the low resistance ridges have the same height. Terminal portions 151, 152, 153, 15 at four corners
And the frame junction insulating portion 131 which is the uppermost layer of the frame of the pressure switch side substrate 1001 together with the pressure sensitive resistors 161, 162, 163, 164 and the high resistance portions 171 and 172.
To form a sealed part. The connection order is
A set of the pressure-sensitive resistor 163, the terminal part 154, the pressure-sensitive resistor 164, the terminal part 151, the pressure-sensitive resistor 161, the terminal part 152, and the pressure-sensitive resistor 162, and the high resistance part 171, the terminal part 153, and the high resistance part 172. . The terminal portion 153 is insulated from the bridge made of the pressure-sensitive resistor by the high-resistance portions 171 and 172.

On the other hand, the pressure-sensitive resistors 162 and 163
The lead portions 157 and 159 extend from the side not connected to the terminal portion 152 and the terminal portion 154 to the sealed structure side, and are connected to the contact portion 157A. Also,
A lead 158 extends from the terminal 153 to the sealed structure side and is connected to the contact 158B. In this way, the contact portion 157A and the contact portion 158B of the bridge circuit side substrate 1002 are made to communicate with each other by the switch portion of the pressure switch side substrate 1001, so that the bridge composed of the four pressure sensitive resistors can operate.

[0020] A change in resistance in the plane direction due to the compressive force in the vertical direction, which depends on the direction on the substrate, is described, for example, in JP-A-8-271363. This uses a (110) plane of a silicon substrate, and a pressure-sensitive resistor having a longitudinal direction in the <1-10> direction and
A bridge is formed squarely by a pressure-sensitive resistor having a longitudinal direction in the <001> direction. Since the <1-10> direction has the largest piezoresistance coefficient π ₁₃ , a pressure-sensitive resistor having a longitudinal direction in the <001> direction can be considered as a substantially fixed resistance.
FIG. 3 is a circuit diagram in the case where the pressure-sensitive resistors 162 and 164 have a longitudinal direction in the <1-10> direction and the pressure-sensitive resistors 161 and 163 have a longitudinal direction in the <001> direction. (A). Thus, if the contact portion 157A and the contact portion 158B is turned by the switch of the pressure switch side substrate 1001 at a constant pressure P ₁ or more, a pressure / output signals of the semiconductor pressure sensor 1000 characteristic diagram shown in FIG. 3 (b) become that way.

[Second Embodiment] In the first embodiment, the low resistance portion of the bridge circuit side substrate 1002 is a raised portion. However, this can be configured by a trench structure as shown in FIG. FIG. 4A shows a semiconductor pressure sensor 1.
FIG. 1B is a cross-sectional view showing the structure of the substrate 800, and FIG. 1B is a plan view showing the structure of a bridge circuit side substrate 1802 having a trench structure constituting the structure. The structure of the pressure switch-side substrate 1801 can be exactly the same as that of the pressure switch-side substrate 1001 of the first embodiment. It is clear that the structure of FIG. 4 (a) has the same effect as the pressure switch of FIG. 1 (b). Also, as shown in FIG. 4B, the trenches T ₁ , T ₂ , T ₃ , T ₄ and the high-resistance portions 171 and 172 form
The silicon substrate 180 and the terminal portion 15 which is a low resistance portion
1, 152, 154, a lead portion 157, 159, a contact portion 157A, a set of pressure-sensitive resistors 161 to 164, and a terminal portion 15
3, insulation from the set of the lead portion 158 and the contact portion 158B is ensured. Note that, in the cross-sectional view of FIG. 4A and the plan view of FIG. 4B, only the low resistance portion is shown using hatching.

[Third Embodiment] By providing two sets of pressure switches, one is a switch for closing a circuit and the other is a short circuit switch, and a semiconductor which outputs an electric signal only between two set pressure differences. It is also possible to form a pressure sensor 1900. This is shown in FIG. 5 as a circuit diagram. The switches S ₁ and S ₂ close at a pressure difference P ₁ or more and P ₂ or more, respectively, where P ₁ <P ₂ . No voltage is applied to the bridge is less than the pressure difference P ₁ (terminal portion 153 and the bridge is not connected) the output (terminal portions 152 and 154
Potential difference between them) is zero. Switch S ₁ is closed is less than the pressure difference P ₁ or P _2, output the voltage to the bridge is applied (a potential difference between terminals 152 and 154) is in accordance with the pressure difference. Switch S ₂ is closed at a pressure differential P ₂ or more,
Since the terminal 151 and the terminal 153 are short-circuited, no current flows through the pressure-sensitive resistor of the bridge. Therefore, the output becomes 0 at this time. This is shown in FIG.

[Fourth Embodiment] Instead of a pressure switch using a double lever, it is possible to simplify the structure by providing a diaphragm on one of the substrates. This is shown in FIG. As shown in FIG. 7A, the switch conductive layer film side substrate 2
001 and the bridge circuit side substrate 2002 having a mesa structure constitute a semiconductor pressure sensor 2000. The bridge circuit side substrate 2002 having the mesa structure is the same as the bridge circuit side substrate 1002 of the first embodiment except that the switch pressing portion 170 is omitted. This is a plan view of FIG.
Shown in In addition, the switch conductive layer film side substrate 2001 has a diaphragm 201 provided on the silicon substrate 200 and has a frame portion bonding insulating portion 230 for pressing a pressure sensitive resistor provided on the bridge circuit side substrate 2002. In addition, a conductive layer film 240 is formed on the inside of the frame portion via the in-frame insulating portion 210. When the diaphragm part 201 is curved upward, the conductive layer film 240 becomes contact points 257A and 258B.
With the conduction, a potential is applied to the bridge circuit, and the semiconductor pressure sensor 2000 can be a semiconductor pressure sensor that outputs an electric signal at a certain pressure or higher. Note that, in the cross-sectional view of FIG. 7A and the two plan views of FIG.
Only the low resistance portion is shown using hatching.

[Fifth Embodiment] The present invention can be applied to a structure having a diffusion gauge electrode as a conventional example.
This is shown in FIG. The semiconductor pressure sensor 3000 is shown in FIG.
(A), the switch conductive layer film side substrate 3001 having the diaphragm portion 301, and the diaphragm portion 381.
And a diffusion electrode side substrate 3002 having Switch conductive layer film side substrate 3 having diaphragm portion 301
001 is the same as the diaphragm 2 shown in the fourth embodiment.
The configuration can be exactly the same as the configuration of the switch conductive layer film-side substrate 2001 having 01. The diffusion electrode side substrate 3002 having the diaphragm portion 381 does not need to be provided with a raised portion particularly at the junction with the switch conductive layer film side substrate 3001. The diaphragm part 381 of the diffusion electrode side substrate 3002
The low-resistance lead portions 3511, 3514, 35
21, 3522, 3524, 3530, 3542, 35
43, 3544 and piezoresistive electrodes 361, 362, 3
63, 364 are provided, and contact portions 3524S, 3530S are provided. The contact portions 3524S and 3530S are located at positions facing the conductive layer film 340 provided on the switch conductive layer film side substrate 3001. In the present embodiment, the piezoresistive electrode 36
The piezoresistive electrodes 362 and 364 are attached to the back surface diaphragm 381 (FIG. 8C) at positions corresponding to the periphery of the back surface diaphragm 381 (portion indicated by the dotted line in FIG. 8C). (Indicated by a dotted line) near the center.

The connection order with the external terminals 351 to 354 is as follows. The first set includes a contact portion 352
4S, lead portion 3542, piezoresistive electrode 363, lead portion 3543, terminal portion 354, lead portion 3544, piezoresistive electrode 364, lead portion 3514, terminal portion 351,
Lead 3511, Piezoresistive electrode 361, Lead 3
521, a terminal portion 352, a lead portion 3522, a piezoresistive electrode 362, a lead portion 3524, and a bridge portion returning to the contact portion 3524S. The other is an external terminal 353,
It is a set of a lead portion 3530 and a contact portion 3530S. still,
In FIG. 8A, the insulating protection film 390 is provided on the diffusion electrode side substrate 3002 with the terminals 351 to 354, the contact portions 3524S, and the contact portions 3524S.
Although the structure has been shown to extend over substantially the entire surface except for 530S, the insulating protective film 390 may be omitted. In addition, a cross-sectional view of FIG.
(B) and (c) In the two plan views, only the low resistance portion is shown using hatching.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a structure of a semiconductor pressure sensor 1000 according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view illustrating an operation thereof.

FIG. 2A is a perspective view showing a structure of a switch-side substrate (SOI) 1001 constituting a semiconductor pressure sensor 1000, and FIG. 2B is a bridge circuit-side substrate 1 also having a mesa structure.
FIG. 2 is a perspective view showing the structure of 002.

3A is a circuit diagram of a bridge and a switch of the semiconductor pressure sensor 1000, and FIG.
FIG.

FIG. 4A is a sectional view showing a structure of a semiconductor pressure sensor 1800 according to a second embodiment of the present invention, and FIG. 4B is a bridge circuit side substrate 180 having a trench structure constituting the semiconductor pressure sensor 1800.
FIG. 2 is a plan view showing the structure of FIG.

FIG. 5 is a circuit diagram of a bridge and a switch of a semiconductor pressure sensor having a short-circuit switch according to a third embodiment of the present invention.

FIG. 6 is a characteristic diagram of the semiconductor pressure sensor 1900.

FIG. 7A is a cross-sectional view illustrating a structure of a semiconductor pressure sensor 2000 according to a fourth embodiment of the present invention, and FIG. 7B illustrates a structure of a switch conductive layer film-side substrate 2001 constituting the semiconductor pressure sensor 2000; Plan view. FIG. 3C is a plan view showing the structure of the mesa bridge circuit-side substrate 2002.

FIG. 8A is a cross-sectional view showing a structure of a semiconductor pressure sensor 3000 according to a fifth embodiment of the present invention, and FIG. 8B shows a structure of a switch conductive layer film-side substrate 3001 constituting the semiconductor pressure sensor 3000. Plan view. (C) is the diffusion electrode side substrate 3002
FIG. 2 is a plan view showing the structure of FIG.

FIG. 9A is a plan view schematically showing a conventional semiconductor pressure sensor using a piezoresistance effect by a diffusion resistance,
(B) is a sectional view thereof, and (c) is a step view schematically showing a conventional semiconductor pressure sensor mounted on a package.

FIG. 10 is a block diagram showing a circuit for displaying pressure at a certain pressure or higher using a conventional semiconductor pressure sensor.

[Explanation of symbols]

1000, 1800, 1900, 2000, 3000
Semiconductor pressure sensor having pressure switch in sealed structure 1001, 1801 Pressure switch side substrate 1002, 2002 Mesa structure bridge circuit side substrate 1802 Trench structure bridge circuit side substrate 2001, 3001 Switch conductive layer film side substrate 3002 Diffusion electrode side substrate 100, 200, 300 Silicon part (SOI) 111 Frame part middle insulating layer (SOI) 112A, 112B Switch leg part insulating layer (SOI) 121 Frame part conductive silicon part (SOI) 122 Switch conductive silicon part (SOI) 131 Frame part Junction insulation part 132 Switch pressure-sensitive insulation part 14A, 14B Switch contact conduction part 150, 280, 380 Silicon substrate 151-154, 251-254, 351-354 Terminal part 157, 158, 159, 257, 258, 259, 3
511, 3514, 3521, 3522, 3524, 3
530, 3542, 3543, 3544 Lead part 157A 158B, 257A 258B, 3524
S, the pressure sensitive resistance 170 switch pressing portion of 3530S contact portions 161, 162, 163, 164, the mesa structure 171,172,271,272 high resistance portion _{T 1, T 2, T 3} , T 4 trenches 201, 301 diaphragm 210, 310 Insulation portion in frame 230, 330 Frame junction insulation portion 240, 340 Conductive layer film 261, 262, 263, 264 Pressure sensitive resistor of trench structure 361, 362, 363, 364 Piezoresistive 390 Insulating film

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kentaro Mizuno 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. (72) Inventor Hiroshi Nonomura Ochi-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture No. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Tokuo Fujitsuka No. 41, Chuchu Yokomichi, Oku-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture, Japan Toyota Central Research Laboratory Co., Ltd. (72) Inventor Hiroshi Nagase Aichi 41 F-term in Toyota Central Research Laboratory, Inc. (reference) 2F055 AA40 BB05 CC02 CC11 DD05 EE14 EE35 FF28 GG01 GG11 GG15 GG31 4M112 AA01 AA07 BA01 CA02 CA16 EA02 EA06 EA13 EA13

Claims (4)

[Claims] 1. A semiconductor pressure sensor having a hermetically sealed structure formed by providing a raised portion on two semiconductor substrates and bonding them together, wherein a circuit portion is provided under a certain pressure by providing a conductor portion and a contact in the hermetically sealed structure. A semiconductor pressure sensor having a pressure switch formed to open and close a circuit above a certain pressure. 2. The semiconductor pressure according to claim 1, wherein a bridge circuit using a piezo resistor is provided on a semiconductor substrate surface inside the closed structure, and the bridge circuit has a structure closed by the pressure switch. Sensor. 3. The structure according to claim 1, further comprising a bridge circuit of a sensing portion having a mesa structure using a piezoresistor in a protruding portion forming the closed structure, wherein the bridge circuit is closed by the pressure switch. Item 2. A semiconductor pressure sensor according to item 1. 4. A closed circuit switch in a closed structure formed to short-circuit the circuit or the bridge circuit by a pressure greater than a pressure at which the pressure switch closes. The semiconductor pressure sensor according to any one of the preceding claims.