JP2013003098A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize a pressure sensor having high reliability to abrupt pressure fluctuation such as water impact, stabilizing temperature characteristics, and capable of saving a cost.SOLUTION: A pressure sensor formed with a strain sensor on a measurement diaphragm includes: a first measurement chamber of a recessed-shape formed on one surface of a first insulation substrate; a first pressure guide hole provided on the first insulation substrate, and communicating to the first measurement chamber; a semiconductor substrate joined with one surface of the first insulation substrate on one surface, and forming the measurement diaphragm; a semiconductor strain gauge provided at a position corresponding to the first measurement chamber on the other surface of the semiconductor substrate; a second insulation substrate joined with the other surface of the semiconductor substrate on one surface; a second measurement chamber symmetrically provided on the one surface of the second insulation substrate so as to oppose to the first measurement chamber; and a second pressure guide hole provided on the second insulation substrate and communicating to the second measurement chamber.

Description

The present invention relates to a pressure sensor.
More specifically, the present invention relates to a pressure sensor that is highly reliable with respect to sudden pressure fluctuations, has stable temperature characteristics, and can be reduced in cost.

FIG. 7 is an explanatory view showing the structure of the main part of a conventional example that is generally used.
In the figure, reference numeral 1 denotes a main body, which includes a columnar neck portion 1A and a block-shaped pressure receiving portion 1B welded and connected at an outer peripheral edge portion 1C of the neck portion 1A. In this case, the neck portion 1A and the pressure receiving portion 1B are made of stainless steel.
The high pressure side-flange 2 and the low pressure side-flange 3 are fixed to both sides of the main body 1 by welding or the like. Both cover flanges 2, 3 have high pressure fluid inlets 4 of high pressure side pressure PH to be measured, low pressure A low-pressure fluid inlet 5 having a side pressure PL is provided.

A pressure measurement chamber 6 is formed in the main body 1, and a center diaphragm 7 and a silicon diaphragm 8 are provided in the pressure measurement chamber 6.
The center diaphragm 7 and the silicon diaphragm 8 are separately fixed to the wall of the pressure measurement chamber 6. The center diaphragm 7 and the silicon diaphragm 8 divide the pressure measurement chamber 6 into two.

Back plates 6A and 6B are formed on the wall of the pressure measurement chamber 6 facing the center diaphragm 7. The center diaphragm 7 is welded to the main body 1 at the periphery.
The entire silicon diaphragm 8 is formed from a single crystal silicon substrate.
Impurities such as boron are selectively diffused on one surface of the silicon substrate to form four strain gauges 80, and the other surface is machined and etched to form a concave diaphragm 8 as a whole.

The four strain gauges 80 are designed such that when the silicon diaphragm 8 is bent under the differential pressure ΔP, two are tensioned and two are compressed, and these are connected to the Wheatstone bridge circuit. Then, a resistance change is detected as a change in the differential pressure ΔP.
The silicon diaphragm 8 divides the neck portion 1 </ b> A into two sensor chambers 81 and 82.
A silicon diaphragm 8 is bonded and fixed to the end surface of the support 9 on the pressure measurement chamber 6 side by a method such as low melting point glass connection.

Pressure introduction chambers 10 and 11 are formed between the main body 1 and the high-pressure side flange 2 and the low-pressure side flange 3.
High pressure side and low pressure side seal diaphragms 12 and 13 are provided in the pressure introducing chambers 10 and 11, and a back plate having a shape similar to that of the seal diaphragms 12 and 13 is formed on the wall of the main body 1 facing the seal diaphragms 12 and 13. 10A, 11A are formed.
The seal diaphragms 12 and 13 and the high pressure side and low pressure side backplates 10A and 11A constitute high pressure side and low pressure side seal diaphragm chambers 12A and 13A.

The seal diaphragms 12 and 13 are welded to the pressure receiving portion 1B at the periphery by seal rings 121 and 131.
In this case, the seal diaphragms 12 and 13 and the seal rings 121 and 131 are made of stainless steel.
The seal diaphragm chambers 12 </ b> A and 13 </ b> A and the pressure measurement chamber 6 are electrically connected through the communication holes 14 and 15.

The sealing diaphragm chambers 12A and 13A are filled with filled liquids 101 and 102 such as silicon oil, and the filled liquids 101 and 102 reach the upper and lower surfaces of the silicon diaphragm 8 through the high-pressure side and low-pressure side conduction holes 16 and 17, respectively. Has reached.
The encapsulated liquids 101 and 102 are divided into two by the center diaphragm 7 and the silicon diaphragm 8, and consideration is given so that the amounts thereof are substantially equal.

In the above configuration, when pressure is applied from the high pressure side, the pressure acting on the high pressure side seal diaphragm 12 is transmitted to the silicon diaphragm 8 by the sealing liquid 101.
On the other hand, when pressure acts from the low pressure side, the pressure acting on the low pressure side seal diaphragm 13 is transmitted to the silicon diaphragm 8 by the sealing liquid 102.
As a result, the silicon diaphragm 8 is distorted in accordance with the pressure difference between the high-pressure side and the low-pressure side, and the strain amount is electrically taken out by the strain gauge 80, and the differential pressure is measured.

JP 05-172676 A JP 2005-049245 A

Such an apparatus has the following problems.
In a transmitter using such a semiconductor pressure sensor, the resistance of the pipe and the amount of oil enclosed are reduced due to the difference in the structure of the conduction hole in which the oil on the high-pressure side and the low-pressure side are enclosed. Different.
The pressure changes due to the expansion and contraction of oil due to temperature changes, but if the amount of oil is slightly different, the pressure is also different, which affects the sensor characteristics.

A center diaphragm is required for overpressure protection, and the number of parts increases, which increases costs.
Furthermore, the pressure may change suddenly due to water impact (water hammer) or the like in the process line under pressure, particularly static pressure (pressure applied to both sides). At this time, because the pipe resistance and oil amount on the high pressure side and low pressure side are different, the pressure on the high pressure side and the low pressure side is shifted due to the oil contraction, and the operating point of overpressure protection is shifted. There is a case. At that time, a large differential pressure may be generated in the sensor unit, and a large differential pressure may be applied to the diaphragm of the pressure sensor, causing the diaphragm to break.

  An object of the present invention is to solve the above-mentioned problems, and to provide a pressure sensor that is highly reliable against sudden pressure fluctuations such as a water shock, has stable temperature characteristics, and can be manufactured at low cost. It is in.

In order to achieve such a problem, in the present invention, in the pressure sensor of claim 1,
In a pressure sensor in which a strain sensor is formed on a measurement diaphragm, a concave first measurement chamber formed on one surface of a first insulating substrate, and the first measurement provided on the first insulating substrate. A first pressure introducing hole communicating with the chamber, a semiconductor substrate having one surface bonded to one surface of the first insulating substrate to form the measurement diaphragm, and the first surface formed on the other surface of the semiconductor substrate. A semiconductor strain gauge provided at a position corresponding to the measurement chamber, a second insulating substrate having one surface bonded to the other surface of the semiconductor substrate, and the one surface of the second insulating substrate. A concave second measurement chamber provided in a symmetrical shape facing the first measurement chamber, and a second pressure guide provided on the second insulating substrate and communicating with the second measurement chamber. And a hole.

In the pressure sensor according to claim 2 of the present invention, in the pressure sensor according to claim 1,
A gap between the measurement diaphragm and the first measurement chamber and a gap between the measurement diaphragm and the second measurement chamber are protected when the measurement diaphragm hits the measurement chamber when an excessive pressure is applied to the measurement diaphragm. It is characterized in that it is adjusted to a gap as expected.

In the pressure sensor according to claim 3 of the present invention, in the pressure sensor according to claim 1 or 2,
First and second semiconductor electrical wirings provided on the other surface of the semiconductor substrate and having one end connected to the strain gauge, respectively, and one end provided on the second insulating substrate and the first and second semiconductors It is characterized by comprising first and second electrodes that are electrically connected to the electrical wiring and the other ends are taken out to the outside.

In the pressure sensor according to claim 4 of the present invention, in the pressure sensor according to any one of claims 1 to 3,
The first and second insulating substrates are made of ceramics or sapphire.

According to claim 1 of the present invention, there are the following effects.
By making the structure of the low pressure side and high pressure side of the pressure sensor symmetrical, the pipe resistance and oil amount on the high pressure side and low pressure side can be changed even when the pressure changes suddenly due to pressure, especially static pressure (pressure applied to both sides). Therefore, even if the oil contracts, the pressure on the high and low pressure sides will be the same. For this reason, even if there is a sudden pressure change due to water impact (water hammer) in the process line, no differential pressure is generated, so that no excessive differential pressure is applied to the diaphragm. Therefore, the sensor is not destroyed.
In addition, since the pressure generated by the expansion and contraction of oil due to a temperature change becomes equal, a pressure sensor with stable temperature characteristics can be obtained.

According to claim 2 of the present invention, there are the following effects.
In addition to the effect of the first aspect, by adjusting the gap, when an excessive pressure is applied, the diaphragm collides with the opposite surface, thereby making it possible to prevent the diaphragm from being destroyed. Therefore, the center diaphragm which is an overpressure protection structure can be eliminated, and a low-cost pressure sensor can be obtained.

According to claim 3 of the present invention, there are the following effects.
First and second semiconductor electrical wirings provided on the other surface of the semiconductor substrate, one end of which is connected to the strain gauge, respectively, and one end provided on the second insulating substrate to the first and second semiconductor electrical wirings There are provided first and second electrodes which are electrically connected and the other end is taken out to the outside.

  Accordingly, the first and second semiconductor electric wirings can be formed simultaneously with the formation of the strain gauge, and an electric signal can be taken out by the first and second electrodes provided on the second insulating substrate. By concentrating on, it is possible to easily handle the extraction of the electrical signal, so that the configuration can be simplified and a low-cost pressure sensor can be obtained.

According to claim 4 of the present invention, there are the following effects.
By adopting sapphire, which is harder to break than glass, a pressure sensor that can achieve higher reliability can be obtained.

It is principal part structure explanatory drawing of one Example of this invention. It is a manufacturing process explanatory drawing of FIG. It is a manufacturing process explanatory drawing of FIG. It is a manufacturing process explanatory drawing of FIG. It is a manufacturing process explanatory drawing of FIG. It is a manufacturing process explanatory drawing of FIG. It is principal part structure explanatory drawing of the prior art example generally used conventionally.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view showing the construction of a main part of one embodiment of the present invention, and FIGS. 2 to 6 are explanatory views of manufacturing steps of FIG.
In the figure, the same symbol structure as in FIG. 7 represents the same function.
Only the difference from FIG. 7 will be described below.

In FIG. 1, the first measurement chamber 22 is formed on one surface of the first insulating substrate 21 and has a concave shape.
The first pressure guide hole 23 is provided in the first insulating substrate 21 and communicates with the first measurement chamber 22.
One surface of the semiconductor substrate 24 is bonded to one surface of the first insulating substrate 21 to form a measurement diaphragm 25.
The semiconductor strain gauge 26 is provided on the other surface of the semiconductor substrate 24 at a position corresponding to the first measurement chamber 22.

One surface of the second insulating substrate 27 is bonded to the other surface of the semiconductor substrate 24.
The second measurement chamber 28 is provided on one surface of the second insulating substrate 27 so as to be symmetric with respect to the first measurement chamber 22 and has a concave shape.
The second pressure introducing hole 29 is provided in the second insulating substrate 27 and communicates with the second measurement chamber 28.

  In this case, the first gap 31 between the measurement diaphragm 25 and the first measurement chamber 22 and the second gap 32 between the measurement diaphragm 25 and the second measurement chamber 28 are overpressured on the measurement diaphragm 25. Is applied to the gaps 31 and 32 so that the measurement diaphragm 25 is protected against the measurement chambers 22 and 28 when.

The first and second semiconductor electrical wirings 33 and 34 are provided on the other surface of the semiconductor substrate 24, and one end thereof is connected to the strain gauge 26.
The first and second electrodes 35 and 36 are provided on the second insulating substrate 27, one end is electrically connected to the first and second semiconductor electrical wirings 33 and 34, and the other end is taken out to the outside. It is.
One end of the first metal pipe 41 is connected to the first insulating substrate 21 by an adhesive 43.

One end of the second metal pipe 42 is connected to the second insulating substrate 27 by an adhesive 43.
In this case, ceramics or sapphire material is used for the first and second insulating substrates.

In the above configuration, as shown in FIG. 2, a strain gauge 102 such as a diffused resistor and first and second semiconductor electrical wirings 103 and 104 having one end connected to the strain gauge 102 are formed on a silicon substrate 101.
As shown in FIG. 3, the silicon substrate 101 is ground and polished to a desired thickness.

As shown in FIG. 4, recesses 107 and 108 and pressure guide holes 109 and 111 communicating with the recesses 107 and 108, respectively, are processed on two sapphire plates 105 and 106.
Then, the through holes 112 and 113 in contact with the other ends of the first and second semiconductor electric wirings 103 and 104 are processed in the sapphire plates 105 and 106.
Electrodes 114 and 115 are formed in the through holes 112 and 113, respectively.

As shown in FIG. 5, the silicon substrate 101 and the sapphire plates 105 and 106 are bonded together by room temperature direct bonding or the like.
As shown in FIG. 6, metal pipes 116 and 117 such as stainless steel are joined to sapphire plates 105 and 106 using an adhesive 118.

As a result,
By making the pressure sensor's low pressure side and high pressure side structures symmetrical, pipe resistance and oil volume on the high pressure side and low pressure side can be changed even if the pressure changes suddenly due to pressure, especially static pressure (pressure applied to both sides). Therefore, even if the oil contracts, the pressure on the high and low pressure sides will be the same. Therefore, the sensor is not destroyed.
In addition, since the pressure generated by the expansion and contraction of oil due to a temperature change becomes equal, a pressure sensor with stable temperature characteristics can be obtained.

  By adjusting the gap, it is possible to design the pressure sensor so that it does not break even if an excessive pressure is applied. Therefore, the center diaphragm 7 which is an overpressure protection structure can be eliminated. Furthermore, when the pressure changes abruptly, since the pressure sensor itself has an overpressure protection structure, a pressure sensor that can prevent the pressure sensor from being destroyed can be obtained.

  Provided on the other surface of the semiconductor substrate 24 and connected to the strain gauge 26 at one end, the first and second semiconductor electrical wirings 31 and 32, and provided on the second insulating substrate 27. First and second electrodes 33 and 34 are provided which are electrically connected to the second semiconductor electrical wirings 31 and 32 and the other ends are taken out to the outside.

  Accordingly, the first and second semiconductor electrical wirings 31 and 32 can be formed simultaneously with the formation of the strain gauge 26, and the first and second electrodes 33 and 34 provided on the second insulating substrate 27 can be electrically connected. Since the signal can be taken out, the electrode can be concentrated on one side, so that the handling of the taking out of the electric signal can be easily performed, so that the configuration can be simplified and a low-cost pressure sensor can be obtained.

  Since ceramics or sapphire, which is harder to break than glass or the like, is employed, a pressure sensor that can achieve higher pressure resistance reliability can be obtained.

  In the above-described embodiment, it has been described that the metal pipes 116 and 117 such as stainless steel are attached to the sapphire plates 105 and 106 by using an adhesive, but the present invention is not limited thereto. The pipes 116 and 117 may be made of Kovar material. In short, any metal material may be used.

  In the above-described embodiment, it has been described that the metal pipes 116 and 117 are joined to the sapphire plates 105 and 106 using an adhesive, but the present invention is not limited thereto. In short, it is sufficient that the metal pipes 116 and 117 can be joined to the plates 105 and 106.

The above description merely shows a specific preferred embodiment for the purpose of explanation and illustration of the present invention.
Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

DESCRIPTION OF SYMBOLS 21 1st insulated substrate 22 1st measurement chamber 23 1st pressure-induction hole 24 Semiconductor substrate 25 Measurement diaphragm 26 Semiconductor strain gauge 27 2nd insulation substrate 28 2nd measurement chamber 29 2nd pressure-induction hole 31 1st 1 gap 32 second gap 33 first semiconductor electrical wiring 34 second semiconductor electrical wiring 35 first electrode 36 second electrode 41 first metal pipe 42 second metal pipe 43 adhesive 101 Silicon substrate 102 Strain gauge 102
DESCRIPTION OF SYMBOLS 103 1st semiconductor electrical wiring 104 2nd semiconductor electrical wiring 105 board 106 board 107 recessed part 108 recessed part 109 pressure hole 111 pressure hole 112 through hole 113 through hole 114 electrode 115 electrode 116 metal pipe 117 metal pipe

Claims (4)

In a pressure sensor in which a strain sensor is formed on the measurement diaphragm,
A concave first measurement chamber formed on one surface of the first insulating substrate;
A first pressure introduction hole provided in the first insulating substrate and communicating with the first measurement chamber;
A semiconductor substrate having one surface bonded to one surface of the first insulating substrate to form the measurement diaphragm;
A semiconductor strain gauge provided on the other surface of the semiconductor substrate at a position corresponding to the first measurement chamber;
A second insulating substrate having one surface bonded to the other surface of the semiconductor substrate;
A concave second measurement chamber provided on the one surface of the second insulating substrate so as to be opposed to the first measurement chamber and having a symmetrical shape;
A second pressure introduction hole provided in the second insulating substrate and communicating with the second measurement chamber;
A pressure sensor comprising: A gap between the measurement diaphragm and the first measurement chamber and a gap between the measurement diaphragm and the second measurement chamber are protected when the measurement diaphragm hits the measurement chamber when an excessive pressure is applied to the measurement diaphragm. The pressure sensor according to claim 1, wherein the pressure sensor is adjusted to such a gap. First and second semiconductor electrical wirings provided on the other surface of the semiconductor substrate and connected to the strain gauge at one end,
The first and second electrodes provided on the second insulating substrate and having one end electrically connected to the first and second semiconductor electric wirings and the other end taken out to the outside are provided. The pressure sensor according to claim 1 or 2. The pressure sensor according to any one of claims 1 to 3, wherein the first and second insulating substrates are made of ceramic or sapphire.