JPH06213751A - Semiconductor differential pressure sensor and differential pressure transmitter - Google Patents

Abstract

PURPOSE:To provide a miniature semiconductor differential pressure sensor having protective function for diaphragm in which a microgap can be obtained between a diaphragm and an excess pressure stopper member. CONSTITUTION:Two fluid pressure detecting diaphragms 2, 3 and a stopper member 1a comprising a semiconductor substrate 1 opposing the diaphragms 2, 3 through a microgap are formed integrally in a common semiconductor chip and piezogauge resistors 7-10 are disposed, respectively, in first and second gaps 4, 5 formed between the diaphragms 2, 3 and the stopper member 1a. The gaps 4, 5 are provided by forming a semiconductor layer for providing the diaphragms 2, 3 on the semiconductor substrate 1 and then removing a semiconductor layer previously formed on the semiconductor substrate 1 by etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor differential pressure sensor and a differential pressure transmitter using the same, and in particular, to miniaturization,
Further, the present invention relates to a semiconductor differential pressure sensor having an overpressure protection function, and a differential pressure transmitter having a structure suitable for mounting on a pipeline, which is downsized using the semiconductor differential pressure sensor.

[0002]

2. Description of the Related Art Conventionally, as a differential pressure sensor provided with two fluid pressure detecting diaphragms and an excessive pressure protection mechanism added to these diaphragms, for example, US Pat.
There is one disclosed in 565,096.

The known differential pressure sensor according to the above disclosure comprises a semiconductor substrate having two diaphragms formed on one surface by etching, and an overpressure stopper member having one recess formed by etching, and the other surface of the semiconductor substrate. The overpressure stopper member is adhered to form a gap mainly composed of the recess between the two members, and a pressure detecting element such as a piezoresistive element is arranged in the gap. Then, the depth of the recess is selected so that the thickness of the gap becomes minute, and the pressure transmitting liquid is filled in the gap to displace the two diaphragms based on the pressure of the fluid to be measured. Is suppressed by the contact with the overpressure stopper member, and the two diaphragms are protected from damage due to overpressure.

In addition to this, the conventionally known differential pressure transmitter has a considerable weight of the differential pressure transmitter when it is mounted on a pipeline or the like and the flow rate of the fluid flowing therethrough is measured. A stanchion (support) must be used to attach the pressure transmitter to the pipeline, and a hole for detecting fluid pressure must be made in the orifice part of the pipeline, and the pressure between the hole and the differential pressure transmitter must be fluid pressure. The structure was such that the introduction pipe was connected.

[0005]

By the way, the known differential pressure sensor has a structure in which a semiconductor substrate having the two diaphragms and an overpressure stopper member having the recess are bonded to each other, that is, the semiconductor. Since the adhesive layer is provided in the contact surface portion between the substrate and the overpressure stopper member, it is difficult to control the minute thickness of the gap formed by the recess as desired. Actually, a manufacturing error of up to several tens of μm to several hundreds of μm occurred. Under such manufacturing conditions, for example, when it is attempted to manufacture a small differential pressure sensor in which the diameter of the diaphragm is slightly less than a few hundreds of μm, the thickness of the adhesive layer becomes larger than the diameter of the diaphragm, which may cause excessive pressure. There is a problem that the overpressure stopper member for protecting the diaphragm does not perform its original function, and the displacement amount of the diaphragm until it comes into contact with the overpressure stopper member becomes almost equal to the thickness of the adhesive layer. Therefore, there is also a problem that the manufacturing yield of the differential pressure sensor becomes extremely low.

In other words, in the known differential pressure sensor,
It has been impossible to realize a differential pressure sensor that is small in size, lightweight, and capable of protecting the diaphragm against excessive pressure.

Further, since the known differential pressure transmitter has a structure in which the pipeline and the differential pressure sensor are connected by a fluid pressure introducing pipe, a small and lightweight differential pressure sensor is temporarily used. Even if it could be realized, the size of the differential pressure transmitter using the small differential pressure sensor would be almost the same as the diameter of the fluid pressure introducing pipe, and conversely, the differential pressure transmitter could be installed in the pipeline. There is also a problem that it becomes difficult to install.

The present invention eliminates the above-mentioned problems, and one of the objects thereof is to obtain a gap having a minute thickness between the semiconductor substrate and the overpressure stopper member, which is small and has a diaphragm. Another object of the present invention is to provide a semiconductor differential pressure sensor capable of achieving the above protection function.

Another object of the present invention is to provide a semiconductor differential pressure sensor in which a gap having a minute thickness can be obtained between a diaphragm (semiconductor layer) and an overpressure stopper member and which has a good manufacturing yield. is there.

Another object of the present invention is to provide a differential pressure transmitter which uses a miniaturized semiconductor differential pressure sensor and which can be easily mounted on a pipeline. .

[0011]

In order to achieve the above-mentioned one object, the present invention provides a pressure detecting diaphragm made of a semiconductor film in a common semiconductor chip, and these diaphragms facing each other with a minute interval. A stopper member made of a semiconductor substrate arranged is integrally formed, and a first means for arranging a piezo gauge resistor is provided in a first gap and a second gap formed between the diaphragm and the stopper member. .

In order to achieve the above-mentioned other object, the present invention firstly comprises a step of forming an etching thin film on one surface of a semiconductor substrate, and secondly, the etching thin film is used for detecting the two fluid pressures. Patterning into a diaphragm shape; third, forming a semiconductor film on one surface of the semiconductor substrate including the patterned etching thin film portion; fourth, providing an opening reaching the patterned etching thin film portion; 5, the step of etching away the patterned etching thin film portion through the opening, and finally the step of sealing the opening,
A second means for manufacturing the semiconductor differential pressure sensor having the structure of the first means is provided.

Further, in order to achieve the above another object, the present invention provides a pressure guide plate attached to an orifice forming portion of a pipeline, a receiving plate having both ends attached to the pressure guide plate, and the receiving plate. A semiconductor differential pressure sensor having the structure of the first means respectively mounted, a signal processing circuit for processing an output signal of the semiconductor differential pressure sensor, and a connection arrangement between the pressure guide plate and the semiconductor differential pressure sensor. And at least two pressure introducing passages provided.

[0014]

According to the first means, the stopper member is formed of a semiconductor substrate when a gap having a desired minute thickness is formed between the two diaphragms and the stopper member. Since the two diaphragms are composed of the semiconductor film, the contact surface between the semiconductor substrate (stopper member) and the semiconductor film (two diaphragms) can be integrally formed by using the semiconductor thin film technology. In this case, if a gap having a desired minute thickness is formed between them, the contact surface between the semiconductor substrate (stopper member) and the semiconductor film (two diaphragms) It becomes possible to form a gap of the desired minute thickness without any consideration of the gap of the adhesive portion formed in the above. Moreover, by adopting the semiconductor thin film technology, It is possible to significantly reduce the thickness of the desired minute in the gap.

According to the second means, when manufacturing the semiconductor differential pressure sensor having the first means, first,
The stopper member is composed of a semiconductor substrate, and then an etching thin film is formed on the semiconductor substrate. Subsequently, the etching thin film is patterned into two diaphragm shapes, and then the patterned etching thin film portion is formed. A semiconductor film is formed on one surface of the semiconductor substrate including the epitaxial film by epitaxial growth, and then the patterned etching thin film portion is removed by etching with an etching solution to form a stopper member composed of two diaphragms made of the semiconductor film and the semiconductor substrate. Since a gap is formed between the semiconductor substrate (stopper member) and the semiconductor film (two diaphragms), it is possible to integrally form the contact surface, thereby reducing the manufacturing yield. Without the thickness of the gap It can be set to the desired thickness of the micro equal to etching a thin film.

Further, according to the third means, the pressure guide plate is directly attached to the orifice forming portion of the pipeline, and the substantially U-shaped receiving plate having both ends attached to the pressure guide plate is provided with the first pressure guide plate. It is possible to attach and hold a miniaturized semiconductor differential pressure sensor including the means of 1 and a signal processing circuit that processes an output signal of the semiconductor differential pressure sensor, and further, the pressure guide plate and the semiconductor differential pressure sensor. Since at least two pressure introduction paths are connected between the pressure difference and the pressure difference, the differential pressure transmitter can be reduced in size and weight, and the differential pressure transmitter can be easily mounted on the pipeline. Will be able to.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a constitutional view showing a first embodiment of a semiconductor differential pressure sensor according to the present invention, (a) is a perspective view thereof, and (b) is a sectional view thereof.

In FIGS. 1A and 1B, 1 is a semiconductor substrate, 1a is a stopper member, 2 is a first diaphragm, 3 is a second diaphragm, 4 is a first gap, and 5 is a gap.
Is a second gap, 6 is a communicating portion, 7 to 10 are first to fourth piezo gauge resistors, and 11 and 12 are first and second opening sealing portions.

Then, in the semiconductor substrate 1, between the surface of the semiconductor substrate 1 (here, the surface constitutes the stopper member 1a) and the first diaphragm 2 and the second diaphragm 3. And a substantially circular first gap 4 and a second gap 5, respectively, and the first gap 4 and the second gap 5 are connected to each other by a communicating portion 6 that connects them.
Are spatially connected by. First gap 4 is first
Of the second gap 5 is connected to the opening sealing portion 11 of
To the opening sealing portion 12. Inside the first gap 4, the first and second piezo gauge resistors 7 and 8 are arranged opposite to each other, and inside the second gap 5, the third and fourth piezo gauge resistors 9 and 10 are the most sensitive <100. They are arranged opposite to each other in the> direction. Also, although not shown in FIG.
A pressure transmitting liquid is sealed and filled in the gap 4 and the second gap 5. Note that the first gap 4
And the thickness d of the second gap 5 is a minute value, for example,
It is set to be several μm to several tens of μm.

2A and 2B are a top view of the first embodiment and an electrical connection diagram including a piezo gauge resistor.

In FIGS. 2A and 2B, 13, 1
Reference numeral 4 denotes first and second excitation voltage supply pads, 15 and 16 denote first and second output extraction pads, and
The same reference numerals are attached to the components shown in FIG.

The first and second output extraction pads 13 and 14 are formed and arranged on the opposite side edge portions of the semiconductor substrate 1, respectively.
Similarly, 5 and 16 are formed and arranged at the opposite side edge portions. Between the first and second output extraction pads 13 and 14, the first and second piezo gauge resistors 7 and 8 are connected in series, and the third and fourth piezo gauge resistors 9 and 10 are also connected in series. The connection point of the first and second piezo gauge resistors 7 and 8 is the first output take-out pad 1
5, the connection points of the third and fourth piezo gauge resistors 9, 10 are connected to the second output extraction pad 16, respectively,
A bridge circuit is configured.

The semiconductor differential pressure sensor of the present embodiment having the above-described structure operates as follows.

Now, as shown in FIG. 1B, when the pressure P1 is applied to the first diaphragm 2 and the pressure P2 larger than the pressure P1 is applied to the second diaphragm 2, The diaphragm 2 is displaced downward (inward of the second gap 5) in proportion to the pressure difference ΔP between the pressures P1 and P2, ΔP = P2-P1, and the volume of the second gap 5 corresponding to the displacement. The first diaphragm 2 is displaced upward (outward of the first gap 4) by the change amount. With the displacement of the first and second diaphragms 2 and 3, the stress generated around the first and second diaphragms 2 and 3 also becomes proportional to the pressure difference ΔP.
First and second piezo gauge resistors 7, 8 arranged in the first gap 4, and third and fourth piezo gauge resistors 9, 10 arranged in the second gap 5.
Will be subject to a corresponding pressure. In addition, since the first to fourth piezo gauge resistors 7 to 10 are bridge-connected as shown in FIG. 2B, they are excited between the first and second excitation voltage supply pads 13 and 14. By supplying a voltage, a voltage signal representing the pressure difference between the pressures P1 and P2, that is, the pressure difference ΔP is extracted from the first and second output extraction pads 15 and 16.

In this case, if the overpressure is applied to the first or second diaphragm 2, 3, for example, the second diaphragm 3, the second diaphragm 3 is greatly lowered (the second gap 5). Of the first gap 4 and the first gap 4 so that the second diaphragm 3 comes into contact with the stopper member 1a before the second diaphragm 3 is displaced and destroyed. If the thickness d of the second gap 5 is adjusted (for example, adjusted to several μm to several tens of μm as described above), the deformation range of the second diaphragm 3 is limited even when an excessive pressure is applied. As a result, the second diaphragm 3 is prevented from displacement destruction. Further, if the displacement of the second diaphragm 3 is limited, the movement of the pressure transmission liquid filled and filled is also limited, so that the displacement of the first diaphragm 2 does not exceed a certain value either. It is also possible to prevent displacement failure of the first diaphragm 2.

In the above description, the case where the overpressure is applied to the second diaphragm 3 is the same as the case where the overpressure is applied to the first diaphragm 2. It is possible to prevent the displacement destruction of not only the diaphragm 2 but also the second diaphragm 3.

Next, FIG. 3 is a block diagram showing a first embodiment of the method of manufacturing the differential pressure sensor of the first embodiment, and FIGS. 3 (a) to 3 (g) show the manufacturing process. It shows the order of.

3A to 3G, 17 is an etching thin film, 17a and 17b are patterned first and second etching thin film portions, 18 is a semiconductor sacrifice layer, 19 is a semiconductor film, and 20 and 21. Are inlets for the first and second etching liquids, and other components that are the same as those shown in FIG. 1 are denoted by the same reference numerals.

First, as shown in FIG. 3A, for example,
On one surface of the semiconductor substrate 1 such as a silicon wafer, a material that is easily etched, for example, silicon dioxide SiO 2.
_An etching thin film 17 made of ₂ is formed.

Next, as shown in FIG. 3 (b), the etching thin film 17 is patterned, and the first and second etchings are performed.
First and second etching thin film portions 17a and 17b are formed in the regions where the diaphragms 2 and 3 are to be formed.

Subsequently, as shown in FIG. 3C, a semiconductor sacrifice layer 18 is formed on one surface of the semiconductor substrate 1, and thereafter, a portion to be a communication path and an etching solution introduction path are formed. Remove the remaining part.

Then, as shown in FIG. 3D, the semiconductor substrate 1 including the first and second etching thin film portions 17a and 17b and the remaining semiconductor sacrifice layer 18 is formed.
A semiconductor film 19, for example, a polysilicon film, which will become the first and second diaphragms 2 and 3, is formed on one surface of the one by means of epitaxial growth or the like.

Subsequently, as shown in FIG. 3E, first and second inlets 20 and 21 for the second etching solution are formed at both ends of the semiconductor film 19 by patterning.

Next, as shown in FIG. 3 (f), the first
Then, the first and second etching thin film portions 17a and 17b and the remaining semiconductor sacrificial layer 18 are removed through an introduction port 20 and 21 of the second etching solution, for example, an etching solution such as hydrogen fluoride HF or hydrogen fluoride. The first and second etching thin film portions 17a and 17b and the remaining semiconductor sacrifice layer 18 are removed by etching by immersing in a mixed solution of HF and ammonium fluoride NH ₄ F, and the removed portions are first and second. The gaps 4 and 5 and the communication path 6 are formed.

Finally, as shown in FIG. 3 (g), the pressure of silicon oil or the like is introduced into the first and second gaps 4 and 5 through the introduction ports 20 and 21 of the first and second etching solutions. The transfer liquid is injected, and after the injection, the introduction port 20,
21 is sealed to form the first and second opening sealing portions 11 and 12.

According to the manufacturing method of the present embodiment, the thickness d of the first and second gaps 4 and 5 is determined only by the thickness of the etching thin film 17, and the thickness of the etching thin film 17 is also determined. Can be appropriately selected and formed from a minimum of several μm, and thus the thickness d can also be appropriately selected within a range of from a minimum of several μm to several tens of μm, and the differential pressure sensor in a good yield state. Can be manufactured.

As described above, in the first embodiment, the stopper member 1 is manufactured by using the first manufacturing means as described above.
Since the first diaphragm 2 and the second diaphragm 3 that are arranged so as to face a are integrally formed on the semiconductor substrate 1, the bonding portion between the semiconductor substrate 1 and the first diaphragm 2 and the second diaphragm 3 is The thickness d of the first and second gaps 4 and 5 is uniquely determined without considering the junction thickness.
Can be selectively formed to have a minute thickness within the range of several μm to several tens of μm, whereby a small and lightweight differential pressure sensor can be obtained.

Next, FIG. 4 is a constitutional view showing a second embodiment of a method of manufacturing a semiconductor differential pressure sensor having a single etching solution inlet, and FIGS. 4 (a) to 4 (g). Indicates the order of the manufacturing process.

In FIGS. 4A to 4G, 23 is a second etching thin film, 24 is an inlet for a single etching solution, 25 is a sealing plate, and other components shown in FIG. The same components as the elements are given the same reference numerals.

First, as shown in FIG. 4A, for example,
On one surface and the other surface of the semiconductor substrate 1 made of a silicon wafer, an etching thin film 17 and a second etching thin film 23 made of a material that is easily etched, for example, silicon dioxide SiO ₂ are formed.

Next, the manufacturing process shown in FIG. 4 (b), the manufacturing process shown in FIG. 4 (c) following that, and FIG. 4 (d) after that.
The manufacturing steps shown in FIG. 3 are exactly the same as the manufacturing steps shown in FIG. 3B, the subsequent manufacturing steps shown in FIG. 3C, and the subsequent manufacturing steps shown in FIG. 3D, respectively.
The description of the manufacturing process shown in FIGS. 4B to 4D is omitted.

Subsequently, as shown in FIG. 4E, a hole is made in the second etching thin film 23, and then the semiconductor sacrifice layer corresponding to the communicating path portion is formed in the semiconductor substrate 1 using the hole as a mask. A hole having a length up to 18 is formed by etching, and a single etching solution inlet 24 is formed.

Next, as shown in FIG. 4F, the first and second etching thin film portions 17a and 17b and the remaining semiconductor sacrifice layer 18 are passed through the single etching solution inlet 24. The first and second etching thin film portions 17a and 17b and the remaining semiconductor sacrifice layer are immersed in an etching solution, for example, hydrogen fluoride HF or a mixed solution of hydrogen fluoride HF and ammonium fluoride NH ₄ F. 18 is removed by etching, and the first and second gaps 4, 5 and the communication passage 6 are formed in the removed portions.

Finally, as shown in FIG. 4 (g), a pressure transmitting liquid such as silicon oil is injected into the first and second gaps 4 and 5 through the single etching liquid inlet 24. After filling and injecting, a sealing plate 25 is bonded to the other surface of the semiconductor substrate 1 to seal the inlet 24 for the single etching solution.

According to the manufacturing method of this embodiment, the first
The thickness d of the first and second gaps 4 and 5 is determined only by the thickness of the etching thin film 17, and the thickness of the etching thin film 17 is
Since the thickness d can be appropriately selected and formed from a minimum of several μm, the thickness d can be appropriately selected within a range of a minimum of several μm to several tens of μm, and the differential pressure sensor can be manufactured with a good yield.

Further, FIG. 5 is a constitutional view showing a third embodiment of a manufacturing method for manufacturing a semiconductor differential pressure sensor made of a single crystal, and FIGS. 5A to 5G show the manufacturing process. It shows the order.

In FIGS. 5A to 5G, 26 is p
Type diffusion layer, 27 is second p type diffusion layer, 28 is n type epitaxial layer, 29 is electrode, 30 is n + layer, 31 is p +
Layers, 32 is a DC power source, 33 is a switch, and others,
The same components as those shown in FIG. 4 are designated by the same reference numerals.

First, as shown in FIG. 5A, for example,
On one surface and the other surface of the n-type silicon single crystal semiconductor substrate 1, an etching thin film 17 and a second etching thin film 23 made of an easily-etchable material such as silicon dioxide SiO ₂ are formed, and then the etching thin film 1 is formed.
7, the formation regions of the first and second diaphragms 2 and 3 are removed by etching, and the p-type diffusion layer 2 is formed in the removed region.
6. For example, a p-type single crystal silicon layer is formed by diffusion.

Next, as shown in FIG. 5B, the region of the etching thin film 17 where the communication path 6 is mainly formed is removed by etching, and the p-type diffusion layer 2 is formed in the removed region.
The second p-type diffusion layer 27, which is the same as that of 6, is shallowly diffused.

Then, as shown in FIG. 5C, after the remaining etching thin film 17 is removed by etching,
An n-type epitaxial layer 28 is epitaxially grown on the entire one surface of the semiconductor substrate 1.

Then, as shown in FIG.
An n + layer 30 is formed on a part of the type epitaxial layer 28, an electrode 29 of aluminum or the like is formed on a part of one surface of the semiconductor substrate 1 including the n + layer 30, and
A portion of the n-type epitaxial layer 28 is provided with the second p-type
The p + layer 31 reaching the type diffusion layer 27 is diffusion-connected, and the p
An electrode 29 made of aluminum or the like is formed on a part of one surface of the semiconductor substrate 1 including the + layer 31.

Then, as shown in FIG. 5 (e), a hole is formed in a part of the second etching thin film 23, and then, as shown in the drawing, between the electrodes 29, 29, for example, 1. After connecting the 5V DC power source 32 and the switch 33, the entire semiconductor substrate 1 is immersed in an alkaline etching solution, for example, an aqueous solution of potassium hydroxide KOH. First, the switch 33 is left open, and the second etching thin film 23 is opened.
The n-type silicon single crystal substrate 1 is etched through these holes to form an inlet 24 for the etching solution.

Next, as shown in FIG. 5F, when the tip of this etching reaches the second p-type diffusion layer 27, the switch 33 is turned on to turn on the n-type epitaxial layer 28.
To the first p-type diffusion layer 26 and the second p-type diffusion layer 27 by etching.
Also, the second gaps 4, 5 and the communication passage 6 are formed.

Finally, as shown in FIG. 5 (g), the semiconductor substrate 1 is taken out of the etching solution, and the introduction port 2 is introduced.
A pressure transmitting liquid such as silicon oil is injected into the first and second gaps 4 and 5 through the injection hole 4, and after the injection, a sealing plate 25 is bonded to the other surface of the semiconductor substrate 1 and the introduction port 24 Is sealed.

Also according to the manufacturing method of the present embodiment, the first
And the thickness d of the second gaps 4 and 5 is determined only by the thickness of the n-type epitaxial layer 28, and
The thickness of the n-type epitaxial layer 28 can be appropriately selected and formed from the minimum of several μm.
Also, similarly, the semiconductor differential pressure sensor can be manufactured in a state where the yield is good, and can be appropriately selected within the range of a minimum of several μm to several tens of μm.

FIG. 6 is a constitutional view showing a second embodiment of the semiconductor differential pressure sensor according to the present invention, (a) is a plan view thereof, and (b) is an electrical connection including the piezo gauge resistance. It is a figure.

In FIGS. 6A and 6B, 34 to 37 are first to fourth static pressure detecting diaphragms 34 '.
To 37 'are third to sixth gaps, 38 to 41 are fifth to eighth piezo gauge resistors, 42 and 43 are third and fourth opening sealing portions, and 44 to 46 are third to fifth openings. The output take-out pad 47 is a temperature sensor, and other components that are the same as those shown in FIG. 1 are denoted by the same reference numerals.

Then, on the semiconductor substrate 1, the first and fourth static pressure detecting diaphragms 34 and 37 are provided at the extended portions on both sides of the first diaphragm 2, and the first and fourth static pressure detecting diaphragms 34 and 37 are provided at the extended portions on both sides of the second diaphragm 3. Second and third static pressure detection diaphragms 35 and 36 are formed and arranged, respectively, and the first and fourth static pressure detection diaphragms 34 to 37 and the surface of the semiconductor substrate 1 are provided with the first and the third static pressure detection diaphragms. Third to sixth gaps 34 'to 37' similar to the second gaps 4 and 5 are formed. In this case, the diameters of the first to fourth static pressure detection diaphragms 34 to 37 are selected to be considerably smaller than the diameters of the first and second diaphragms 2 and 3.
First and fourth opening sealing portions 11 and 43 are provided between the first diaphragm 2 and the first and fourth static pressure detection diaphragms 34 and 37, and the second diaphragm 3 and the second diaphragm 3 are provided.
The second and third opening sealing portions 12 and 42 are provided between the first and third static pressure detection diaphragms 35 and 36.
Second and fourth piezo gauge resistors 8, 10 are arranged side by side in the first gap 4, and first and third piezo gauge resistors 7, 9 are arranged side by side in the second gap 5, respectively.
The fifth to eighth piezo gauge resistors 38 to 41 are arranged in the third to sixth gaps 34 'to 37' corresponding to the fourth to fourth static pressure detecting diaphragms 34 to 37, respectively. Fifth and sixth piezo gauge resistors 38, 3
9, and the seventh and eighth piezo gauge resistors 40, 41
Are the first and second excitation voltage supply pads 13,
14 are connected in series, and the connection points of the fifth and sixth piezo gauge resistors 38 and 39 are connected to the third output extraction pad 44, and the connection point of the seventh and eighth piezo gauge resistors 40 and 41 are the fourth. The output extraction pads 45 are respectively connected. A temperature sensor 47 is arranged at one corner of the semiconductor substrate 1, one end of the temperature sensor 47 is connected to the second excitation voltage supply pad 14, and the other end is connected to the fifth output extraction pad 46.

Here, the first and second diaphragms 2 and 3 and the first to fourth static pressure detecting diaphragms 3 are provided.
The area ratio of 4 to 37 is defined by the first and second gaps 4,5.
And the third to sixth gaps 34 'to 37' have the same thickness, they are determined by the differential pressure measurement range and the static pressure measurement range. For example, the differential pressure measurement range is 1 Kg / cm ² , and the static pressure measurement range is 50 Kg / cm ^2.
, Then the first and second diaphragms 2, 3
S1 and the areas of the first to fourth static pressure detecting diaphragms 34 to 37 are S2, the area ratio S1 is
/S2=1/50=0.02.

In this case, in this embodiment, the areas of the first to fourth static pressure detecting diaphragms 34 to 37 are relatively small, and therefore the third to sixth gaps 34 'to 3'.
Since it is difficult to arrange a plurality of piezo gauge resistors inside 7 ′, each of the static pressure detection diaphragms 34 to 3 is provided.
Four 7 are arranged, and one piezo gauge resistor 38 to 41 is arranged in each.

The semiconductor differential pressure sensor of the present embodiment having the above-described structure operates as follows.

First, the first and second diaphragms 2, 3
The first and second diaphragms 2 and 3 are displaced by the two fluid pressures P1 and P2 applied to the first and second electric signals representing the pressure difference ΔP between the two pressures P1 and P2 based on the displacement. It is almost the same as the operation of the first embodiment in that it is taken out from the output taking-out pads 15 and 16 of.

Further, in this embodiment, the first to fourth
No. 3 corresponding to the static pressure detection diaphragms 34 to 37 of
The fifth to eighth piezo gauge resistors 38 to 41 are arranged in the to sixth gaps 34 'to 37',
Moreover, since the piezo gauge resistors 38 to 41 are connected in a bridge and the excitation voltage is supplied between the opposite vertices of one of the bridges, the third and fourth output extractions connected to the other opposite vertices of the bridge are taken out. An electric signal representing the absolute static pressure is taken out from the pads 44 and 45. Besides this,
A temperature sensor 47 is arranged on the semiconductor substrate 1 so that the temperature around the semiconductor substrate 1 is detected and the detected output is the fifth value.
Is taken out from the output take-out pad 46 of.

Also in the present embodiment, as in the first embodiment, the first manufacturing means is used to form the first diaphragm 2 and the second diaphragm 3 which are arranged so as to face the stopper member 1a, in the semiconductor substrate. Since it is integrally formed with the first substrate 1, the first and second gaps 4, 4 are uniquely formed without considering the joint thickness of the joint portion between the semiconductor substrate 1 and the first diaphragm 2 and the second diaphragm 3. 5, and the thickness d of each of the third to sixth gaps 34 'to 37' can be selectively formed to a minute thickness within the range of several μm to several tens of μm, thereby obtaining a small and lightweight differential pressure sensor. be able to.

Next, FIG. 7 is a constitutional view showing a third embodiment of the semiconductor differential pressure sensor according to the present invention, (a) is a plan view thereof, (b) is a sectional view thereof, and Figure 8
It is an electrical connection diagram containing a piezo gauge resistance in a 3rd example.

In FIGS. 7A and 7B and FIG.
48 to 51 are ninth to twelfth piezo gauge resistors, 52
Is a differential amplifier, and the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

The difference between this embodiment and the first embodiment is that the first embodiment has a communication passage 6 connecting the first gap 4 and the second gap 5, and While the pressure transmitting liquid is sealed and filled in the gap 4 and the second gap 5, the present embodiment does not have the communication passage 6 and the pressure transmitting liquid is sealed and filled. Points that we have not
The first embodiment has a first gap 4 and a second gap 5.
In each, two piezo gauge resistors 7 to 8,
9 to 10 are arranged, in the present embodiment, four piezo gauge resistors 48 to 51 and 7 to 10 are provided in the first gap 4 and the second gap 5, respectively.
In the first embodiment, one differential pressure sensor unit in which four piezo gauge resistors 7 to 10 are bridge-connected is used to detect the differential pressure. The only difference is that two differential pressure sensor units in which four piezo gauge resistors 7 to 10 and 48 to 51 are connected in two bridges and a differential amplifier 52 are used. In addition, the present embodiment and the first embodiment are used. There is no difference between

Since the operation of this embodiment is almost the same as the operation of the first embodiment described above, a detailed description of the operation of this embodiment will be omitted here, but especially in this embodiment. As described above, includes the static pressures applied to the first and second diaphragms 2 and 3 by the two differential pressure sensor units respectively arranged in the first gap 4 and the second gap 5. Since the fluid pressure is detected and the static pressure components in the pressure detected by the two differential pressure sensor units are canceled by the differential amplifier 52, the differential amplifier 5
2 outputs the first and second diaphragms 2, 3
An electric signal proportional to the differential pressure of the fluid pressure applied to each is derived.

Also in this embodiment, by using the first manufacturing means, the first diaphragm 2 and the second diaphragm 3 which are arranged to face the stopper member 1a are attached to the semiconductor substrate 1
The first and second gaps 4, 5 are uniquely formed without considering the bonding thickness of the bonding portion between the semiconductor substrate 1 and the first diaphragm 2 and the second diaphragm 3. It is the same as in the first and second embodiments that the thickness d can be selected and formed to a minute thickness within the range of several μm to several tens of μm, and thereby a small and lightweight differential pressure sensor can be obtained. . Further, since the present embodiment is a non-communication type differential pressure sensor having no communication portion 6, the first gap 4 is
Also, there is an advantage that the second gap 5 functions sufficiently even if the pressure transmitting liquid is not sealed and filled in the second gap 5.

In each of the above-described embodiments, the case where the semiconductor differential pressure sensor is manufactured is described as using the first embodiment of the manufacturing method, but in addition to using the first embodiment of the manufacturing method. Of course, the second embodiment of the manufacturing method or the third embodiment of the manufacturing method can be used as appropriate, and the same effects can be obtained by different manufacturing methods.

Next, FIG. 9 is a block diagram showing an example of the correction circuit means for improving the accuracy of the differential pressure detection output.

In FIG. 9, 53 is a differential pressure sensor, 54 is a multiplexer (MPX), 55 is a programmable gain amplifier (PGA), 56 is an analog-digital converter (A / D), and 57 is a digital-analog converter ( D /
A), 58 is a voltage-current converter (V / I), 59 is a memory, and 60 is a microprocessor unit (MPU).

Data indicating various characteristics of the differential pressure sensor 53 is measured and stored in the memory 59 in advance.

The operation of the correction circuit means will now be described. A plurality of output signals detected by the differential pressure sensor 53, for example, the output signal of the differential pressure sensor section in the second embodiment and the static pressure sensor section. The output signal and the temperature detection signal obtained by the temperature sensor 47 are selected by the MPX 54, and a predetermined one of them is selected and output. The selected signal is amplified by the PGA 55 and converted into a digital signal by the A / D 56. Then, the MPU 60
The digital signal, which is raw data indicating the static pressure and the temperature, is corrected and calculated by using the data stored in the memory 59, and the high-precision digital signal with high precision is supplied to the D / A 57. The D / A 57 converts this high precision digital signal into an analog signal, and then V / I 5
Reference numeral 8 converts this analog signal into a current output and sends it as a measured value to the outside.

Next, FIG. 10 is a block diagram showing an embodiment of a differential pressure transmitter constructed by using the above-mentioned semiconductor differential pressure sensor.

In FIG. 10, 61 is a semiconductor differential pressure sensor (semiconductor substrate), 62 is a signal processing circuit, 63 is a pressure guide plate,
64 is an output lead pin, 65 is a substantially U-shaped receiving plate, 66
Is a pressure fluid introduction path, 67 is a fluid pressure introduction hole, and 68 is a screw hole.

The pressure guiding plate 63 is provided with a plurality of fluid pressure introducing holes 67 at its intermediate portion and screw holes 68 at both ends thereof, and one surface (lower side surface) of the receiving plate having a substantially U shape. Both ends of 65 are attached. This substantially U-shaped receiving plate 6
A plurality of output lead pins 64 are attached to the supporting arm portion of 5, and a semiconductor differential pressure sensor (semiconductor substrate) 6
1 and MPX54, PGA55, A / D56, D / A5
7, a signal processing circuit 62 including a V / I 58, a memory 59, an MPU 60, etc. is mounted and fixed, a semiconductor differential pressure sensor (semiconductor substrate) 61 and an output lead pin 64, and a signal processing circuit 62 and an output lead pin 64. Are conductively connected to each other. In addition, the plurality of fluid pressure introducing holes 67
Are respectively formed on the semiconductor differential pressure sensor (semiconductor substrate) 61 through the fluid pressure introducing passages 66.
The diaphragms 2 and 3 are connected to communicate with each other. When in use, the pressure guide plate 63 is directly screwed to the orifice portion (not shown) of the pipeline through the screw hole 68.

In the above structure, when the fluid pressure is applied to the first and second diaphragms 2 and 3 through the two fluid pressure introducing passages 66, an electric signal proportional to the difference between the pressures is applied to the signal processing circuit 62. And the electric signal is led to the outside through the output lead pin 64.

In this case, the semiconductor differential pressure sensor 61 used in this embodiment is a small semiconductor differential pressure sensor as described in the first to third embodiments, and the pressure guide plate is used. When directly connected to the orifice portion of the pipeline via 63, the fluid pressure detecting hole of the pipeline and the diaphragm of the semiconductor differential pressure sensor 61 are connected through the fluid pressure introducing passage 66. There is.

Therefore, the differential pressure transmitter has a very small shape and can be easily mounted on a pipeline.

FIG. 11 is a block diagram showing a state in which the differential pressure transmitter shown in FIG. 10 is mounted on a pipeline. FIG. 11A shows a case where the differential pressure transmitter is mounted on a small diameter pipe. b) shows the case of mounting on a large diameter pipe.

11A and 11B, 69 is a receiving plate capable of mounting and holding a plurality of circuit components, 70 is a mounting screw, 71 is a pipeline, 72 is an orifice, 73 is a sensing / amplifying circuit section, 74 is a signal processing circuit section, and 75
Is an interface portion, and 76 is a second pressure guide plate. Other than that, the same components as those shown in FIG. 1 are designated by the same reference numerals.

When the differential pressure transmitter is mounted on a small diameter pipe, the pressure guiding plate 63 is directly attached to the portion of the pipeline 71 where the orifice 72 is formed by the mounting screw 70, and the receiving plate attached to the lower side of the pressure guiding plate 63. The sensing / amplifying circuit section 73, the signal processing circuit section 74, the interface section 75, and the like are mounted and fixed on 69. In this case, the point that the first and second diaphragms 2 and 3 of the semiconductor differential pressure sensor (not shown) and the fluid pressure introduction hole 67 of the pressure guide plate 63 are connected by the fluid pressure introduction passage 66 is described above. It is as follows.

On the other hand, when the differential pressure transmitter is mounted on a large diameter pipe, first, the second pressure guide plate 76 is directly attached to the portion of the pipeline 71 where the orifice 72 is formed by the mounting screw 70, and then the pressure guide plate 63. Is also attached to the lower side of the second pressure guide plate 76 by the mounting screw 70, and the receiving plate 69 is attached to the lower side of the pressure guide plate 63 as described above. In this case, the second pressure guide plate 76 has a gap between the positions of the fluid pressure detection holes provided in the portion where the orifice 72 of the pipeline 71 is formed and the position of the fluid pressure introduction hole 67 provided in the pressure guide plate 63. The second pressure guiding plate 76 has a fluid pressure introducing hole formed in a key-shaped bent state inside the second pressure guiding plate 76, which serves as an adapter for adjusting the difference from the gap. Also,
If it is still not possible to adjust the distance between the positions by using only one second pressure guide plate 76, then another second pressure guide plate 76 may be used as an adapter.

As described above, according to the differential pressure transmitter of this embodiment, since the semiconductor differential pressure sensor according to the present invention is used,
The size and weight of the semiconductor device are extremely small, the mounting on the pipeline 71 is extremely easy, and the diaphragms 2, 3 of the semiconductor differential pressure sensor are irrespective of the distance between the positions of the holes for fluid pressure detection of the pipeline 71. It becomes possible to align with the interval of.

[0087]

As described above, according to the present invention,
Since the contact surfaces of the stopper member 1a (semiconductor substrate 1) and the first and second diaphragms 2 and 3 (semiconductor film) are integrally formed, the first contact surface having the desired minute thickness d is formed between them.
It is possible to form the second gaps 4 and 5, and it is possible to obtain a semiconductor differential pressure sensor that is small in size and lightweight and has a function of protecting the first and second diaphragms 2 and 3. .

Further, according to the present invention, the first and second
In the case of manufacturing a semiconductor differential pressure sensor having the gaps 4 and 5, the first and second gaps 4 and 5 are formed into a desired film thickness, and the semiconductor thin film 1 is easy to etch.
7, 18 to the first and second diaphragms 2, 3
After the (semiconductor film) is formed, it is removed by etching, so it is possible to use ordinary semiconductor thin film manufacturing technology.
It is possible to form the first and second gaps 4 and 5 having a desired minute thickness d, and it is possible to improve the manufacturing yield.

Further in accordance with the present invention, the pipeline 7
1, a pressure guiding plate 63 directly mounted on the pressure guiding plate 63, receiving plates 65 and 69 mounted on the pressure guiding plate 63 and mounting and fixing the semiconductor differential pressure sensor according to the present invention, a fluid pressure detecting hole of a pipeline 71, and the semiconductor. Since the fluid pressure introducing path 66 that connects the diaphragms 2 and 3 of the differential pressure sensor 61 is used, a small and lightweight differential pressure transmitter that can be easily mounted on the pipeline 71 can be obtained. There is an effect.

[Brief description of drawings]

FIG. 1 is a perspective view and a sectional view showing a configuration of a first embodiment of a semiconductor differential pressure sensor according to the present invention.

FIG. 2 is a top view of the semiconductor differential pressure sensor shown in FIG. 1 and an electrical connection diagram including a piezo gauge resistor.

FIG. 3 is a configuration diagram showing a first embodiment of a method of manufacturing the semiconductor differential pressure sensor shown in FIG.

FIG. 4 is a configuration diagram showing a second embodiment of a method of manufacturing a semiconductor differential pressure sensor having a single etching solution inlet.

FIG. 5 is a configuration diagram showing a third embodiment of a manufacturing method for manufacturing a semiconductor differential pressure sensor made of a single crystal.

FIG. 6 is a plan view showing a configuration of a second embodiment of a semiconductor differential pressure sensor according to the present invention and an electrical connection diagram including a piezo gauge resistance.

7A and 7B are a plan view and a sectional view showing the configuration of a third embodiment of the semiconductor differential pressure sensor according to the present invention.

8 is an electrical connection diagram including a piezo gauge resistance in the semiconductor differential pressure sensor shown in FIG.

FIG. 9 is a block diagram showing an example of a correction circuit means for increasing the accuracy of differential pressure detection output.

FIG. 10 is a configuration diagram showing an embodiment of a differential pressure transmitter configured by using the semiconductor differential pressure sensor according to the present invention.

FIG. 11 is a configuration diagram showing a state when the differential pressure transmitter shown in FIG. 10 is mounted on a pipeline.

[Explanation of symbols]

 1 Semiconductor Substrate 1a Stopper Member 2 First Diaphragm 3 Second Diaphragm 4 First Gap 5 Second Gap 6 Communication Portion 7 First Piezo Gauge Resistance 8 Second Piezo Gauge Resistance 9 Third Piezo Gauge Resistance 10 4th Piezo gauge resistor 11 First opening sealing portion 12 Second opening sealing portion 13 First excitation voltage supply pad 14 First excitation voltage supply pad 15 First output extraction pad 16 Second output extraction pad 17 Etching thin film 17a Patterned first etching thin film portion 17b Patterned second etching thin film portion 18 Semiconductor sacrificial layer 19 Semiconductor film (diaphragm) 20 First etching liquid inlet 21 Second etching liquid inlet 23 Second etching thin film 24 Single etching solution inlet 25 Sealing plate 26 p-type diffusion layer 27 second p-type diffusion layer 28 n-type epitaxial layer 29 electrode 30 n + layer 31 p + layer 32 DC power supply 33 switch 34 first static pressure detection diaphragm 34 'third gap 35 Second static pressure detection diaphragm 35 'Fourth gap 36 Third static pressure detection diaphragm 36' Fifth gap 37 Fourth static pressure detection diaphragm 37 'Sixth gap 38 Fifth piezo gauge resistance 39 6th piezo gauge resistance 40 7th piezo gauge resistance 41 8th piezo gauge resistance 42 3rd opening sealing part 43 4th opening sealing part 44 3rd output extraction pad 45 4th output extraction pad 46 4th Output pad 5 47 Temperature sensor 48 9th piezo gauge resistance 49 10th piezo gauge resistance 50 11th piezo gauge resistance Ezo gauge resistance 51 12th piezo gauge resistance 52 Differential amplifier 53 Differential pressure sensor 54 Multiplexer (MPX) 55 Programmable gain amplifier (PGA) 56 Analog-digital converter (A / D) 57 Digital-analog converter (D / A) 58 voltage-current converter (V / I) 59 memory 60 microprocessor unit (MPU) 61 semiconductor differential pressure sensor (semiconductor substrate) 62 signal processing circuit 63 pressure plate 64 output lead pin 65 substantially U-shaped receiving plate 66 pressure fluid Introducing path 67 Fluid pressure introducing hole 68 Screw hole 69 Receiving plate capable of mounting and holding a plurality of circuit components 70 Mounting screw 71 Pipeline 72 Orifice 73 Sensing / amplifying circuit section 74 Signal processing circuit section 75 Interface section 76 Second pressure plate

Front page continuation (72) Inventor Tomoyuki Tobita 882 Ichige, Ichima, Katsuta, Ibaraki Hitachi, Ltd. Measuring Instruments Division (72) Inventor Yoshimi Yamamoto 882, Ige, Katsuta, Ibaraki Hitachi, Ltd. Within the Business Unit (72) Inventor Akira Nagasu 882 Ichige, Ita, Katsuta City, Ibaraki Prefecture Hitachi Ltd., Measuring Instruments Business Unit

Claims (10)

[Claims] 1. A common semiconductor chip is integrally formed with two fluid pressure detecting diaphragms made of a semiconductor film and a stopper member made of a semiconductor substrate facing each other with a minute gap therebetween. A semiconductor differential pressure sensor, wherein piezo gauge resistors are arranged in first and second gaps formed between both diaphragms and the stopper member, respectively. 2. The first and second gaps are spatially coupled to each other through a communication part, and a pressure transmitting liquid is enclosed in the gaps. Semiconductor differential pressure sensor. 3. The semiconductor differential pressure sensor according to claim 1, wherein the first and second gaps are isolated from each other. 4. In the common semiconductor chip, a plurality of static pressure detection diaphragms made of semiconductor films and a facing member made of a semiconductor substrate facing each other with a minute interval are integrally formed on the diaphragm. Piezo gauge resistors are arranged in the gaps respectively formed between the plurality of diaphragms and the facing member, and the diameters of the plurality of static pressure detection diaphragms are larger than the diameters of the fluid pressure detection diaphragms. The semiconductor differential pressure sensor according to claim 1, wherein the semiconductor differential pressure sensor has a small size. 5. The method according to claim 1, which is formed through the following steps.
A method for manufacturing the semiconductor differential pressure sensor described. 1. 1. a step of forming an etching thin film on one surface of a semiconductor substrate, 2. patterning the etching thin film into the shape of the two fluid pressure detecting diaphragms; 3. a step of forming a semiconductor film on one surface of the semiconductor substrate including the patterned etching thin film portion; 4. A step of providing an opening reaching the patterned etching thin film portion, 5. Etching away the patterned etching thin film portion through the opening; Sealing the opening. 6. A step of forming a semiconductor sacrificial film in a region connecting at least two etching thin film portions after forming the patterned etching thin film portion and before forming the semiconductor film is added. Item 6. A method for manufacturing a semiconductor differential pressure sensor according to Item 5. 7. The step of providing the opening comprises providing an opening reaching the semiconductor sacrificial film on the other surface of the semiconductor film or the semiconductor substrate.
A method for manufacturing the semiconductor differential pressure sensor described. 8. The method for manufacturing a semiconductor differential pressure sensor according to claim 5, wherein the semiconductor substrate is silicon, the etching thin film is silicon dioxide, and the semiconductor film is polysilicon. 9. The method for manufacturing a semiconductor differential pressure sensor according to claim 5, wherein the semiconductor substrate and the semiconductor film are n-type single crystal silicon, and the etching thin film is p-type single crystal silicon. 10. The semiconductor differential pressure sensor and the semiconductor differential sensor according to claim 1, wherein the pressure guiding plate is mounted on the orifice forming portion of the pipeline, the receiving plate is mounted on the pressure guiding plate, and the receiving plate is mounted on the receiving plate. A differential pressure transmitter comprising: a signal processing circuit for processing an output signal of a pressure sensor; and at least two pressure introducing passages connected and arranged between the pressure guide plate and the semiconductor differential pressure sensor.