JPH11304615A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly accurate small sensor having a wide range ability. SOLUTION: A rigid body 58 is formed annularly along the outer circumference of the central region on a differential pressure diaphragm and a protrusion 57 is formed annularly along the outer circumference of the central region on the diaphragm also on the p-type diffusion layer 51b. A plate member 18 for preventing the inclination of the rigid body 58 incident to deformation of the diaphragm is fixed onto the body 58. When a differential pressure diaphragm ΔP of a specified level or above is applied to the diaphragm, the outer circumference of the central region 65a thereof is restricted completely by the protrusion 57 and the rigid body 58. Consequently, peaks of tensile stress appear in the vicinity of the outer fringe part in the central region 65a and in the vicinity of the peripheral region. Four piezoelectric resistors are thus arranged on the diaphragm, respectively, in the vicinity of the outer fringe part in the central region 65a and in the vicinity of the peripheral region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor pressure sensor used for measuring pressure in various plants and the like.

[0002]

2. Description of the Related Art As one of diffusion type pressure sensors utilizing the piezoresistance effect of a diffusion resistance layer formed on a silicon pellet having a diaphragm structure, a semiconductor pressure sensor for differential pressure described in Japanese Patent Application Laid-Open No. Hei 8-295085 is known. Have been.
This semiconductor pressure sensor (hereinafter, referred to as a conventional pressure sensor)
There are two structural ideas for suppressing non-linear errors: (a) formation of a boss in the central area on the diaphragm, and (b) peripheral area excluding the rim where the diffusion layer is formed. Has been made thinner.

[0003]

However, the above conventional pressure sensor has a drawback that it cannot cover a wide pressure range from low pressure to high pressure because the pressure sensitivity is constant. . In order to solve this disadvantage, a plurality of diaphragms having mutually different pressure receiving areas, that is, a plurality of pressure sensors having mutually different pressure sensitivities may be mounted on one chip. A new problem of enlargement occurs.

By the way, in order to realize a composite sensor for detecting both the differential pressure and the static pressure, it is necessary to mount a plurality of diaphragms, that is, a differential pressure diaphragm and a static pressure diaphragm on one chip. Therefore, the chip tends to be large.

Accordingly, it is a first object of the present invention to provide a small and highly accurate semiconductor pressure sensor having a wide rangeability. It is a second object of the present invention to provide a compact semiconductor pressure sensor capable of detecting both static pressure and differential pressure.

[0006]

In order to solve the above-mentioned problems, the present invention is directed to a differential pressure applied to a differential pressure diaphragm by a plurality of strain gauges arranged on a differential pressure diaphragm fixed on a substrate. A pressure sensor for detecting distortion of the differential pressure diaphragm according to the above, wherein the differential pressure diaphragm displaced to the substrate side, a supporting member for supporting the outer peripheral portion of the central region of the substrate facing surface of the differential pressure diaphragm. A rigid member formed on an outer peripheral portion of a central region of a surface of the diaphragm for differential pressure opposite to the substrate facing surface, and an inclination preventing member for preventing inclination of the rigid member with respect to the diaphragm for differential pressure; Is provided in a central region of the diaphragm for differential pressure and an outer peripheral region surrounding the central region.

According to this structure, when the differential pressure applied to the differential pressure diaphragm exceeds a predetermined value, the vertical movement of the outer peripheral portion of the central region of the differential pressure diaphragm is restricted by the support member and the rigid member. . Accordingly, at this time, in the stress distribution on the differential pressure diaphragm, peak values σ ₁ and σ _{2 of} the tensile stress appear in the central region and the outer peripheral region, respectively (see FIG. 4B). This means that the central region and the outer peripheral region of the differential pressure diaphragm can function as independent diaphragms, respectively. To be more specific, the outer peripheral region the larger peak value sigma ₁ of appears functions as sensitive low pressure diaphragm to changes in the applied pressure difference, the central region appears peak value sigma ₂ The smaller, It functions as a high-pressure diaphragm that is insensitive to changes in the applied differential pressure.

Accordingly, even when only one diaphragm for differential pressure is mounted, a plurality of pressure sensitivities can be achieved as in the case where a plurality of diaphragms for differential pressure are mounted. That is, a wide pressure range from low pressure to high pressure can be covered without the disadvantage of increasing the size of the chip.

Further, even if the differential pressure diaphragm is deformed by the application of the differential pressure, the inclination preventing member prevents the rigid member from tilting, so that the stress loss accompanying the rigid member inclination is prevented, and the pressure loss on the differential pressure diaphragm is reduced. In the stress distribution, a clearer peak appears than when only the rigid member and the support member are provided. Accordingly, the provision of the plate for preventing inclination improves the pressure sensitivity in both the central region and the outer peripheral region of the diaphragm for differential pressure, and suppresses non-linear errors in their outputs.

In such a pressure sensor, if an outer peripheral region surrounding a central region of the differential pressure diaphragm is formed thinner in a region excluding a region where the strain gauge is disposed than in a region where the strain gauge is disposed. Further improvement in pressure sensitivity and suppression of non-linear errors are achieved.

Further, as a post having a pressure inlet opposed to a surface of the differential pressure diaphragm opposite to the substrate facing surface, an opening area of the pressure inlet is smaller than an area of a central region of the differential pressure diaphragm. When the post is attached, excessive deformation of the differential pressure diaphragm is prevented by the contact between the post and the rigid member or the like, so that the differential pressure diaphragm can be prevented from being broken when an excessive pressure (absorption pressure) is introduced.

Further, in such a pressure sensor, if the rigid member is formed on the outer peripheral portion without being divided, and a plate material that seals a space surrounded by the rigid member is used as the inclination preventing member, Since an airtight space is formed between the central region and the plate member for preventing inclination, the central region of the diaphragm functions as a static pressure diaphragm.
Therefore, even though only one diaphragm is mounted, both the static pressure and the differential pressure can be detected as in the case where the static pressure diaphragm and the differential pressure diaphragm are mounted. That is, both the static pressure and the differential pressure can be detected without the disadvantage of increasing the size of the chip.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the basic structure of the semiconductor pressure sensor according to the present embodiment will be described. This semiconductor pressure sensor has a piezoresistance effect of a p-type high-concentration impurity diffusion layer (hereinafter referred to as piezoresistance) formed on a diaphragm having a two-layer structure of an insulating film (SiON or the like) and an n-type single-crystal silicon film. Is a diffusion type pressure sensor that detects both the differential pressure and the static pressure, that is, a composite sensor. Its basic structure is shown in Fig. 1.
As shown in FIG.
Chip 100 having a static pressure sensitive diaphragm 66 and a post 59 having a pressure inlet 68
(Usually made of Fe-Ni alloy or other metal), adhesive layer 60
(Usually made of low melting point glass, Pyrex glass or other glass).

Hereinafter, referring to FIG. 2, the structure of a sensor chip 100 which is a characteristic part of this semiconductor pressure sensor will be described.
This will be described in more detail.

The sensor chip 100 includes a p-type high-concentration impurity diffusion layer 51b (hereinafter referred to as a p-type diffusion layer 51) formed by diffusing boron or other impurities on an n-type single crystal silicon substrate 51a.
b).

The static pressure diaphragms 66a, 66b, 66c, 66d located at the respective corners of the sensor chip 100
Is deformed by the difference (static pressure) between the pressure applied to the surface and the reference pressure inside the cavity 62 formed in the p-type diffusion layer 51b. 54 is a diaphragm 66 for each of these static pressures.
This is a thick aluminum film that closes a through hole 64 opened for etching a sacrifice layer (described later) used when forming a, 66b, 66c, and 66d.

On the other hand, the differential pressure diaphragm 65 located substantially at the center of the sensor chip 100 has a pressure applied to its surface and a pressure introduced from a pressure inlet 63 formed in the p-type diffusion layer 51b. Deformation due to the difference (differential pressure). In the present embodiment, in order to suppress non-linear errors and improve pressure sensitivity, the diaphragm 65 for differential pressure is used.
Of the outer peripheral region 65b surrounding the central region 65a of the piezoresistive 31a, 31b, 31c, 31d are thinned only region 65b ₂ excluding the rib region 65b ₁ which is formed.

On the surface of the differential pressure diaphragm 65, along the boundary between the central region 65a and the outer peripheral region 65b, the insulating oxide film 37 and the rigid member 58 are annularly formed.
Are laminated. The rigid member 58 is not limited to an annular shape, and may be a polygon or the like, or may be divided in the middle.

An adhesive layer 17 is formed on the distal end surface of the rigid member 58 by low-melting glass, Pyrex glass, or the like, and a through hole for applying pressure to the central region 65a side of the differential pressure diaphragm 65 from above. A tilt-preventing glass plate 18 (hereinafter, referred to as a tilt-preventing plate 18) having a hole 18a is covered. By providing such a plate 18 for preventing inclination, the inclination of the rigid member 58, which causes a loss of the stress applied to the diaphragm 65 for differential pressure when a differential pressure is applied, is prevented. However, between the end face 59a of the post 59 and the inclination preventing plate 18 so that the deformation of the differential pressure diaphragm 65 is not hindered by the contact between the inclination preventing plate 18 and the end face 59a of the post 59. The initial gap on the order of μm (Δt _{0 in} FIG. 1)
Needs to be provided). For industrial reasons, etc., an adhesive layer 6 of sufficient thickness to provide such an initial gap
In the case where it is difficult to form 0, for example, as shown in FIG. 3, a protrusion 59b having an appropriate height along the outer edge of the end face 59a of the post 59 may be formed.

If the outer diameter Z of the inclination preventing plate 18 is made larger than the inner diameter D of the pressure introducing port 68, excessive deformation of the differential pressure diaphragm 65 is prevented by the inclination preventing plate 18, so that an excessively large value is obtained. It is also useful to prevent the differential pressure diaphragm 65 from being broken when pressure (absorption) is introduced.

Also, the protrusions 57 are formed on the p-type diffusion layer 51b side so as to vertically correspond to the rigid member 58, that is, annularly along the outer periphery of the central region 65a of the differential pressure diaphragm 65.
Is formed. By providing an initial gap on the order of μm (corresponding to Δt ₁ in FIG. 1) between the tip of the projection 57 and the back surface of the differential pressure diaphragm 65, the tip of the projection 57 is in an initial no-load state. The back surface of the pressure diaphragm 65 is prevented from contacting. Needless to say, the protrusion 57 is also useful for preventing the differential pressure diaphragm 65 from being broken when an excessive pressure (pressurized) is introduced.

As shown in FIG. 4A, when a differential pressure .DELTA.P of a predetermined value or more is applied to the differential pressure diaphragm 65, the outer periphery of the central region 65a moves up and down and the protrusion 57 and the rigid member 58 move. And are completely blocked by. According to the force balance condition, the differential pressure diaphragm 65 at this time is used.
As shown in FIG. 4 (b), the stress distribution on the surface of the
The following equation (1) is added to both the vicinity of the outer edge portion in 5b.
The peaks σ ₂ and σ _{1 of the} tensile stress given by (2) appear.

Σ ₁ = 3 × (X ² −Z ² ) × ΔP / (16 × h ² ) (1) σ ₂ = 3 × Y ² × ΔP / (16 × h ² ) (2) , X are the outer diameters of the differential pressure diaphragm 65,
Y and Z are the inner and outer diameters of the rigid member 58, h
Is the thickness of the diaphragm 65 for differential pressure.

Therefore, in the present embodiment, near the outer edge of the outer peripheral region 65b on the surface of the differential pressure diaphragm 65,
Each of the four piezoresistors 31a, 31b, 31c, 31d is arranged at substantially equal center angles so that the longitudinal direction thereof is directed to the crystal axis <110> direction on the (100) crystal plane. That is, two piezoresistors 31a and 31c having a longitudinal direction in the radial direction of the differential pressure diaphragm 65 and two piezoresistors 31b and 31d having a longitudinal direction in the tangential direction of the differential pressure diaphragm 65 are arranged. . In the following, a piezoresistor having a longitudinal direction in the radial direction of the differential pressure diaphragm 65 is called an L gauge, and
A piezoresistor having a longitudinal direction in the tangential direction is referred to as a T gauge.

Further, the four piezoresistors 32a, 32b, 32c, and 32d are also provided at substantially equal central angles at the outer periphery of the central region 65a on the surface of the differential pressure diaphragm 65 at the same length. The orientation was such that the direction was directed to the crystal axis <110> direction on the (100) crystal plane. That is, 2
Two L gauges 32a, 32c and two T gauges 32b,
32d are arranged.

As shown in FIG. 6, the voltage given by the equation (3) is obtained by four piezoresistors 31a, 31b, 31c and 31d arranged near the outer edge of the outer peripheral region 65b of the differential pressure diaphragm 65. a Wheatstone bridge 40a that outputs V _1, alternatively, four piezoresistors 32a arranged near the outer edge of the central region 65a of the differential pressure diaphragm 65, 32 b, 32c, 32d
By, are a Wheatstone bridge 40b that outputs a voltage V ₂ given by Equation (4).

V ₁ = (1/2) × π ₄₄ × (1-ν) × σ ₁ × V (3) V ₂ = (1/2) × π ₄₄ × (1-ν) × σ ₂ × V (4) where ν is the Poisson's ratio of the differential pressure diaphragm 65, and π ₄₄ is the piezoresistors 31a, 31b, 31c, 3
The shear piezoresistive coefficients of 1d, 32a, 32b, 32c, 32d, and V is the excitation voltage.

According to the equation (5) derived from the above equations (1), (2), (3) and (4), if the three shape parameters X, Y and Z are adjusted, the two Wheatstone bridges 40a and 40b
It can be seen that the output voltage ratio V ₁ : V ₂ can be freely changed.

V ₁ / V ₂ = (X ² −Z ² ) / Y ² (5) That is, the present semiconductor pressure sensor is provided with the differential pressure diaphragm 65.
Although only one is provided, as shown in FIG. 7, the applied differential pressure can be detected with two different pressure sensitivities. For example, two Wheatstone bridges 40a, 40b of the output voltage ratio V _1: V ₂ is 4: to be 1, three shape parameter ratio X: Y: the Z 5: 2:
If it is set to 3, it is possible to detect a differential pressure based on a predetermined pressure sensitivity S and a pressure sensitivity 4 × S which is four times the predetermined pressure sensitivity S.

[0031] Thus, for example, by the threshold processing of the microcomputer switches the pressure sensitivity in accordance with the range of the measured pressure in the low pressure range of 0 ≦ ΔP ≦ ΔP _1, linearity high lesser pressure sensitive output The differential pressure is calculated from the voltage V _1, and in the high-pressure range of ΔP ₁ <ΔP <ΔP ₂ , the output voltage V has good linearity but low pressure sensitivity.
By calculating the differential pressure data from ₂ , high-precision measurement in a wide pressure range from low pressure to high pressure can be realized.

Even in the case where the inclination preventing plate member 18 is not provided, it is possible to detect the differential pressure with two different pressure sensitivities by one differential pressure diaphragm 65 as in the above case. However, in this case, as shown in FIG. 5A, the rigid member 58 tilts toward the center side due to the deformation of the differential pressure diaphragm 65, and a stress loss occurs near the rigid member 58. As shown in ()), the stress distribution on the surface of the differential pressure diaphragm 65 does not show a clear peak as in the case where the inclination preventing plate 18 is provided. In the present embodiment, such a rigid member 5
By providing the plate 18 for preventing inclination, which prevents the inclination of 8, a sharper stress distribution appears on the surface of the diaphragm 65 for differential pressure, thereby further improving pressure sensitivity and suppressing non-linear errors. Has been achieved.

Each of the static pressure diaphragms 66a, 66
Piezoresistors 33a, 33b, 33c, 33d are arranged one by one also on the surfaces of b, 66c, 66d. The four piezo resistors 33a, 33b, 3
3c, the 33d, are a Wheatstone bridge 40c for outputting a voltage V ₃ corresponding to the static pressure (see Fig. 6).

In this embodiment, the diffusion resistor 34 is formed on the silicon chip 100 so that the longitudinal direction thereof is (100).
The diffusion resistance 34 (hereinafter, referred to as a temperature sensor 34) is disposed so as to be directed to the crystal axis <100> direction on the crystal plane, that is, to be sensitive only to a change in ambient temperature.
The excitation voltage V from the power supply
(See FIG. 6).

Reference numerals 35, 36 denote lead lines drawn from the respective piezoresistors to constitute a Wheatstone bridge or the like, and 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10. 11,
12,13,14,15,16 are the lead lines 35,3
6 is a contact pad (aluminum) for connecting each other. Out of these lead wires 35 and 36, the lead wire 35 laid in the vicinity of the piezoresistor or on the surface of the differential pressure diaphragm 65 or the like where the influence of the temperature hysteresis is large is formed by high concentration diffusion of boron and other impurities. It is desirable that the diaphragm 6 for differential pressure be used.
The lead wire 36 laid in an area where the influence of temperature hysteresis is small, such as the outside of 5, may be formed of aluminum or other low-resistance conductor.

Next, a method of manufacturing the semiconductor pressure sensor according to the present embodiment will be described with reference to FIG.

(A) A p-type diffusion layer 51b is formed on the surface of an n-type single crystal silicon substrate 51a by diffusing impurities such as boron at a high concentration. Further, by implanting ions such as phosphorus partially into the p-type diffusion layer 51b, five n-type impurity diffusion layers 55a and 55
5b, that is, an n-type impurity diffusion layer 55a (hereinafter, referred to as a first sacrificial layer 55a) to be a base of the differential pressure diaphragm 65, and each of the static pressure diaphragms 66a, 66b, 66
An n-type impurity diffusion layer 55b (hereinafter, referred to as a second sacrificial layer 55b) to be a base for c and 66d is formed. However, due to the formation of the pressure introduction port 63 and the projection 57, a device for forming the first sacrificial layer 55a having a different thickness depending on the position, for example, in the process of implanting ions into the p-type diffusion layer 51b, A device such as switching the acceleration voltage between two stages is required.

After the formation of the first sacrifice layer 55a and the second sacrifice layer 55b is completed, an insulator such as SiON, SiO ₂ , SiN, or Al ₂ O ₃ is deposited by using the CVD method. As a result, these diffusion layers 51b,
An insulating film 52 having an appropriate thickness is formed on 55a and 55b.

Then, after the n-type single crystal silicon is bonded on the insulating film 52, an n-type single crystal silicon film 53 having an appropriate thickness is finished by grinding. Alternatively, the n-type single-crystal silicon film 53 is formed by epitaxial growth, polysilicon deposition, or the like.

(B) Thereafter, impurities such as boron are diffused into the n-type single crystal silicon film 53, so that the piezo resistors 31a, 31b, 31c, 3
1d, 32a, 32b, 32c, 32d, 33a, 33b, 3
3c, 33d and a temperature sensor 34 are formed. Specifically, four piezoresistors are formed in the vicinity of the outer edge of the region to be the central region 65a of the differential pressure diaphragm 65 and near the outer edge of the region to be the outer peripheral region 65b, respectively. Diaphragms 66a, 66b, 66c, 6
One piezoresistor is formed in each of the regions to be 6d. Further, the temperature sensor 34 is formed in a thick region on the sensor chip 100 where no diaphragm is formed.

Further, each Wheatstone bridge 40
Lead lines 35 and 36 are formed on n-type single crystal silicon film 53 so that a, 40b and 40c (see FIG. 6) are formed. Specifically, the lead line 35 is formed by high concentration diffusion of impurities such as boron in a region where the influence of the temperature hysteresis is large, and the lead line 36 is deposited in other regions by vapor deposition of a low resistance conductor such as aluminum. To form Alternatively, all the lead lines may be formed by diffusion of impurities.

(C) After that, using a photoresist, a resist pattern 56 is formed on the n-type single crystal silicon film 53, and then, using this resist pattern 56 as a mask,
By etching the single-crystal silicon film 53 and the insulating film 52, a portion where the static pressure detection is not adversely affected is obtained.
A through-hole 64 connecting the outside and the second sacrificial layer 55b is formed. Then, an etching solution (for example, hydrazine) having a high selectivity of SiON and p-type diffusion layer with respect to n-type silicon is introduced from a portion to be a pressure introduction port 63 and the through hole 64, so that the first sacrificial layer 55a is formed. And the second sacrificial layer 55b are selectively removed by etching. And
When the unnecessary etchant is recovered, the protrusion 57 and the pressure introduction port 63 are completed.

(D) Thereafter, after removing the resist pattern 56, an insulating oxide film 37 is formed in a band along the outer periphery of a region to be the central region 65a of the differential pressure diaphragm 65.

Then, the through holes 64 are filled with a thick film 54 of aluminum or the like to hermetically seal the cavity 62 from which the second sacrificial layer 55b has been removed. Thus, the static pressure diaphragms 66a, 66b, 66c, 66d are completed. In the same step, the insulating film 37 is
An aluminum thick film or the like to be the rigid member 58 is formed. When a thicker rigid member 58 is required, it is desirable to separately provide a step of forming only the rigid member 58.

(E) Thereafter, an adhesive layer 17 of low melting point glass, Pyrex glass or the like is formed on the rigid member 58, and a through hole 18a
Paste the opened glass plate.

Further, by etching, the area where the piezoresistor is not formed (the area 65b ₂ excluding the rib area 65b ₁ ) in the area to be the outer peripheral area 65b of the differential pressure diaphragm 65 can be reduced in thickness. Diaphragm 6
5 is completed. Note that the etching at this time may reach the insulating film 52 as shown in FIG. 9, or may reach the insulating film 52 as shown in FIG. 10 if there is no through hole.

Then, the sensor chip thus completed is fixed to the post 59, whereby the semiconductor pressure sensor according to the present embodiment is completed.

The arrangement of the piezoresistors on the differential pressure diaphragm 65 is not limited to that shown in FIG. For example, in the peripheral region 56b of the differential pressure diaphragm 65, as shown in FIG. 11, two L gauges 31a and 31c are provided near the inner edge where the peak of the compressive stress (σ _{3 in} FIG. 4) appears. Two T gauges 31b, 31
d may be arranged. In the peripheral region 65b of the differential pressure diaphragm 65, as shown in FIG. 12, two L gauges 31b and 31d are arranged near the inner edge where the peak σ _{3 of the} compressive stress appears, and the peak of the tensile stress is set. Two L gauges 31 near the outer edge where σ ₁ appears
a, 31c may be arranged. As shown in FIG. 13, two T-gauges 31b and 31d are arranged near the inner edge where the peak σ _{3 of the} compressive stress appears in the peripheral region 65b of the diaphragm 65 for differential pressure, so as to reduce the tensile stress. Two T gauges 31a and 31c may be arranged near the outer edge where the peak σ ₁ appears.

In the present embodiment, the pressure sensitivity of one differential pressure diaphragm 65 is made plural,
It has achieved two problems that were conventionally difficult to achieve, namely, improvement of the rangeability and miniaturization of the sensor chip 100. However, when emphasis is placed on miniaturization of the sensor chip 100, etc. Glass plate material without through hole 18a for pressure introduction as prevention plate material 18.
(With a thickness of about 200 μm). When such a plate for preventing inclination is used, an airtight space is formed between the central region 65a of the diaphragm 65 and the plate 18 for preventing inclination, so that the central region 65a of the diaphragm 65 is introduced from the pressure inlet 63. It functions as a static pressure diaphragm that responds to the difference (static pressure) between the applied pressure and the reference pressure inside the airtight space. Therefore, it is difficult to achieve an improvement in the rangeability, but it is not necessary to form the static pressure diaphragm 66 at the corner of the sensor chip 100, so that a smaller sensor chip 100 can be provided.

[0050]

According to the present invention, a small-sized semiconductor pressure sensor having wide rangeability and high accuracy can be provided.

Further, according to the present invention, a small semiconductor pressure sensor capable of detecting both static pressure and differential pressure can be provided.

[Brief description of the drawings]

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

FIG. 2A is a top view of a sensor chip of a semiconductor pressure sensor according to one embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along the line ABCD-DE. is there.

FIG. 3 is a sectional view of a semiconductor pressure sensor according to one embodiment of the present invention.

FIG. 4A is a sectional view conceptually showing a deformation of a differential pressure diaphragm according to one embodiment of the present invention, and FIG.
FIG. 4 is a stress distribution diagram on the differential pressure diaphragm at that time.

FIG. 5A is a cross-sectional view conceptually showing a deformation of a differential pressure diaphragm having no inclination preventing plate member, and FIG. 5B is a stress distribution diagram on the differential pressure diaphragm at that time. It is.

FIG. 6 is a connection diagram of a piezo resistor.

FIG. 7 is a diagram showing output characteristics of the semiconductor pressure sensor according to one embodiment of the present invention.

FIG. 8 is a diagram illustrating a method for manufacturing the semiconductor pressure sensor according to one embodiment of the present invention.

FIG. 9 is a cross-sectional view of the sensor chip of the semiconductor pressure sensor according to one embodiment of the present invention, taken along the line ABCDCE.

FIG. 10 is a sectional view of the sensor chip of the semiconductor pressure sensor according to one embodiment of the present invention, taken along the line ABCDCE.

11A is a top view of a sensor chip of a semiconductor pressure sensor according to an embodiment of the present invention, and FIG. 11B is a cross-sectional view taken along the line ABCD-DE. is there.

12A is a top view of a sensor chip of a semiconductor pressure sensor according to an embodiment of the present invention, and FIG. 12B is a cross-sectional view taken along the line ABCD-DE. is there.

13A is a top view of a sensor chip of a semiconductor pressure sensor according to one embodiment of the present invention, and FIG. 13B is a cross-sectional view taken along the line ABCD-DE. is there.

[Explanation of symbols]

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16… Contact pad 17… Adhesive layer 18… Tilt prevention plate 18a… Tilt prevention plate Through holes 31a, 31b, 31c, 31d ... Piezoresistors 32a, 32b, 32c, 32d ... Piezoresistors 33a, 33b, 33c, 33d ... Piezoresistors 34 ... Temperature sensor 35 ... Lead wire 36 ... Lead wire 37 ... Insulating oxide film 40a, 40b, 40c: Wheatstone bridge 51a: n-type single-crystal silicon substrate 51b: p-type high-concentration impurity diffusion layer 52: insulating film 53: n-type single-crystal silicon film 54: aluminum thick film that blocks through holes 55a, 55b ... n-type impurity diffusion layer (first sacrifice layer 55a, second sacrifice layer 55b) 56 resist pattern 57 projection provided on p-type high concentration impurity diffusion layer 58 rigid member 59 post 59a post end face 59b post Convex part 60 Adhesive layer 62 Cavity for reference pressure of static pressure diaphragm 63 Pressure inlet 64 Through hole 65 Differential pressure diaphragm 65 a Central area of differential pressure diaphragm 65 b Differential pressure Thinned region 66 ... static pressure diaphragm 66a of the outer peripheral region of the rib region 65b ₂ ... differential pressure diaphragm of the outer peripheral region of the peripheral region 65b ₁ ... differential pressure diaphragm of the diaphragm, 66b, 66c, 66d ... the static pressure diaphragm 68 ... pressure opening 100… Sensor chip

Claims (5)

[Claims] 1. A pressure sensor for detecting distortion of a differential pressure diaphragm according to a differential pressure applied to the differential pressure diaphragm by a plurality of strain gauges arranged on a differential pressure diaphragm fixed on a substrate. A supporting member that supports the differential pressure diaphragm displaced toward the substrate at an outer peripheral portion of a central region of the substrate facing surface of the differential pressure diaphragm; and a center of a surface of the differential pressure diaphragm opposite to the substrate facing surface. A rigid member formed at an outer peripheral portion of the region; and an inclination preventing member for preventing inclination of the rigid member with respect to the diaphragm for differential pressure, wherein the plurality of strain gauges include a central region of the diaphragm for differential pressure and the central region. And a peripheral region surrounding the pressure sensor. 2. The pressure sensor according to claim 1, wherein an outer peripheral area surrounding a central area of the differential pressure diaphragm is thinner in an area excluding an area where the strain gauge is arranged than in an area where the strain gauge is arranged. A pressure sensor characterized by being formed. 3. The pressure sensor according to claim 1, further comprising: a post having a pressure introduction port facing a surface of the differential pressure diaphragm opposite to a substrate facing surface, wherein an opening area of the pressure introduction port is provided. Is smaller than the area of the central region of the differential pressure diaphragm. 4. The pressure sensor according to claim 1, further comprising a temperature sensor for detecting a temperature of the pressure sensor. 5. One of the first, second, third and fourth aspects of the present invention.
3. The pressure sensor according to claim 1, wherein the rigid member is formed in the outer peripheral portion without being divided, and the inclination preventing member is a plate member that seals a space surrounded by the rigid member. .