JP3607420B2 - Dry type pressure detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an absolute pressure type pressure detection device that measures the pressure of fluids such as chemical plants and the like, controls the fluid pressure, and is used for operation control of the entire plant.
[0002]
[Prior art]
For example, it is well known that measuring the pressure of a chemical plant and the pressure in a semiconductor device is indispensable for operating the plant and the semiconductor device safely and efficiently. For this purpose, an absolute pressure type pressure detection device has been widely used.
[0003]
In such a pressure detection device, as can be understood from the pressure oscillator and the pressure sensor disclosed in JP-A-4-5532 and JP-A-3-185325, the pressure-receiving unit that detects the pressure, and the pressure-receiving unit And a signal converter for converting the detected signal into a generalized analog signal or digital signal. The pressure receiving unit has a reference chamber, and is configured to detect a pressure difference between the pressure in the reference chamber and the measured pressure.
[0004]
FIG. 9 is a schematic cross-sectional view showing a general structure of an absolute pressure type pressure detection device in a conventional example. This absolute pressure type pressure detection device measures the pressure in chemical plants and in semiconductor devices, and monitors and controls process pressure, maintains equipment for semiconductor devices, and maintains process quality. Widely used as a control device.
[0005]
In FIG. 9, the pressure receiving body 20 includes a semiconductor pressure sensor 11 or a capacitive type pressure sensor 11. Further, the process connection flange 10 has a pressure application port 101, and the pressure receiving unit main body 20 and the detection unit main body are connected to the process flange 10 so that pressure is transmitted from the pressure application port 101 to the pressure receiving unit main body 20. It is incorporated by a screw part formed on the inner surface.
[0006]
The pressure of the process is received by the diaphragm 3 in the pressure receiving unit main body 20, and this pressure is transmitted to the pressure sensor 11 through the sealed liquid 31 sealed between the diaphragm 3 and the pressure sensor 11.
[0007]
Piezoresistive elements 111 to 114 are disposed on the surface side of the pressure sensor 11 that contacts the sealed liquid 31. Further, a groove portion 120 is formed on the surface side of the pressure sensor 11 that does not contact the sealed liquid 31, and the groove portion 120 forms a space portion together with the fixing base 2.
[0008]
Further, the piezoresistive elements 111 to 114 are connected to the printed circuit board 4 via the conductive material 52 and the conductive pins 41 filled in the holes formed in the housing 3. And the piezoresistive elements 111-114 (Rg1-Rg4) form a Wheatstone bridge circuit like the equivalent circuit diagram shown in FIG. The pressure sensor 11 is provided with a temperature compensating resistor 115 (RT).
[0009]
Then, the output voltage EPV1 of the Wheatstone bridge circuit is compensated by the temperature compensating resistor 115 to obtain the output voltage ETV1. This output voltage ETV1 is transmitted as a pressure signal to the host control device via the electric signal converter.
In FIG. 9, 9 is a housing, and 21 is a sealing pin inserted into a hole formed in the fixing base 2 in order to seal the groove 120.
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional absolute pressure type pressure detector, the pressure of the process is set to the diaphragm 3 in order that the pressure sensor 11 which is a pressure-electric signal converter avoids direct contact with the process fluid to be measured. Because of this, there are many components and the configuration is complicated.
[0011]
Furthermore, a high vacuum region (1 x 10^-5  When the pressure in the vacuum region below Torr) was measured, the internal sealing liquid 31 would boil, so measurement was impossible. The general measurement area of the conventional pressure detection device is a low 1 to 10 Torr range at a temperature of 100 ° C. even if a sealed oil with the best boiling temperature is used and a degassing process is performed at the time of sealing. It is a vacuum region.
For this reason, the high vacuum region (1 × 10^-5  It has been desired to realize a pressure detection device that can measure the pressure in a vacuum region below Torr) and has a simple configuration.
[0012]
An object of the present invention is to provide a high vacuum region (1 × 10 10) while having a simple configuration.^-5  It is to realize a dry type pressure detecting device capable of measuring a pressure in a vacuum region below Torr.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
(1) Fluid to be measuredCombined with a pressure detection element that detects the pressure of the gas and a temperature detection element that detects the temperatureIn a dry type pressure detection apparatus comprising a semiconductor pressure sensor and a pressure receiving unit comprising a fixing base for fixing the semiconductor pressure sensor, and a signal processing unit connected to the pressure receiving unit and processing a detection signal from the semiconductor sensor, The semiconductor pressure sensor has a thin portion and a thick portion by forming a recess in the central portion of one surface, and a plurality of pressure detection elements are arranged on the thin portion on the opposite surface where the recess is formed. And a plurality of connection terminals connected to the pressure detection element are disposed on the thick wall portion, and the fixing base has a recess formed in a central portion, and around the recess.,Connection terminal abovePlacement positionCorresponding toPenetrating between the surface facing the signal processing unit from the surface facing the semiconductor pressure sensor,A plurality of lead terminals connected to the signal processing unit are formed, and the connection terminal and the lead electrode are aligned with the surface on which the concave portion of the fixing base is formed and the surface on which the pressure detection element of the semiconductor pressure sensor is disposed. The pressure reference chamber is formed by the concave portion of the fixing base by the bonding, and the sensor and the fixing are formed on the concave portion forming surface of the semiconductor pressure sensor and the surface of the fixing base in contact with the fluid to be measured. An oxide film is formed on both the tables, and the pressure transmitted from the fluid to be measured in contact with the recess of the semiconductor pressure sensor is detected by the pressure detecting element.
[0014]
Since the pressure is transmitted directly in contact with the fluid to be measured, the surface opposite to the surface on which the pressure detection element of the semiconductor pressure sensor for detecting the pressure of the fluid to be measured is disposed, The filled liquid can be omitted, the assemblability is excellent, the entire detection device is miniaturized and the number of components is small, the reliability of the device is improved and the maintenance can be easily performed.
In addition, since there is no encapsulated liquid, restrictions on the range of use can be eliminated, the measurement area can be expanded, and labor saving of the instrument can be achieved.
[0018]
(2)Preferably, in (1) above, an ethylene tetrafluoride film is formed in place of the oxide film.
[0019]
(3)Preferably, in (2) above, a protective film made of gold is formed in place of the oxide film.
(4)Preferably, in (2) above, a protective film made of platinum is formed in place of the oxide film.
(5)Preferably, in the above (2), the space formed by the concave portion of the fixed base and the semiconductor sensor forms a vacuum reference pressure chamber sealed from the periphery.
(6)Preferably, in the above (5), at least one vacuum measurement is performed on a surface of the fixed base to which the semiconductor pressure sensor is bonded, and in a region other than the region where the semiconductor pressure sensor is bonded. Sensors are arranged.
[0021]
(7) Preferably, in the above (6),The sensor for vacuum measurement is a sensor that utilizes the fact that the heat loss due to the heat conduction of the fluid to be measured changes with the pressure of the fluid to be measured.
[0022]
(8) Preferably, the above (6), The sensor for vacuum measurement isThe sensor detects the number of product ions, and measures the pressure of the fluid to be measured according to the number of product ions detected.
[0023]
(9) Preferably, the above (6)A first electrode is disposed on the surface of the semiconductor pressure sensor on which the pressure detection element is disposed, a second electrode facing the first electrode is disposed in the concave portion of the fixed base, and the signal processing unit is The capacitance value between the first electrode and the second electrode is detected.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an absolute pressure type pressure detection device according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of an absolute pressure type dry type pressure detection apparatus according to a first embodiment of the present invention. FIGS. 2 and 3 are fixed to a sensor section of the pressure detection apparatus shown in FIG. It is a figure which shows the structure of a stand.
[0028]
In FIG. 1 to FIG. 3, the entire configuration of the absolute pressure type pressure detection device is schematically shown as a sensor unit set 100 </ b> A, 100 </ b> B for detecting the pressure of a process fluid and signals from these sensor unit sets 100 </ b> A, 100 </ b> B. The signal processing unit 190 in which a signal processing circuit for processing the above is accommodated.
[0029]
The multi-function pressure sensor chip 11 is a (100) plane n-type single crystal silicon, and has a circular thin portion 110 at substantially the center of the sensor chip 11, and one surface of the thin portion 110, That is, the groove part 120 is formed in the surface on the side where the pressure fluid contacts.
[0030]
Then, by applying the first process pressure and the second process pressure to the one surface and the other surface of the thin portion 110 (the surface opposite to the surface on which the pressure fluid contacts), respectively, the thin portion 110 (diaphragm) is a strain generating body sensitive to pressure and operates as a pressure sensitive diaphragm for pressure detection.
[0031]
On the other surface of the pressure-sensitive diaphragm 110, P-type resistance elements (gauge resistance elements) 111 to 114, which are first pressure sensors, are arranged in the <110> axis direction in which the piezoresistance coefficient in the (100) plane is maximized. Each is formed by a thermal diffusion method or an implantation method in a direction parallel or perpendicular to the crystal axis.
[0032]
The arrangement positions of the resistance elements 111 to 114 are in the vicinity of the fixed portion where the radial and circumferential distortions generated on the pressure-sensitive diaphragm 110 when pressure is applied are maximized.
Further, as the arrangement directions of these resistance elements 111 to 114, the resistance elements 111 and 113 are set in the radial direction, and the resistance elements 112 and 114 are set as the tangential directions. One end is connected, and the other end of each resistance element is connected to the detection terminal to form a bridge circuit as shown in FIG.
[0033]
In addition, a resistive element 115 that is sensitive to temperature is formed in a thick portion other than the pressure sensitive diaphragm 110 of the sensor chip 11 in a direction insensitive to pressure. By extracting the change in resistance value of the resistance element 115 from the output terminal, the temperature of the process fluid can also be measured.
[0034]
The shape and thickness of the pressure-sensitive diaphragm 110 are changed to a desired shape by anisotropic wet etching or dry etching from the side opposite to the surface on which the resistance elements 111 to 114 are arranged, depending on the pressure to be sensitive. The thickness is set, and the groove 120 is formed.
[0035]
When the measured fluid pressure of the process is applied while the measured fluid is in contact with the groove portion 120, the resistance elements 111 to 114 on the pressure sensitive diaphragm 110 are subjected to the distortion generated in the diaphragm 110, and the piezoresistive effect. Since the resistance changes due to, the change can be taken out as a signal.
[0036]
The multi-function pressure sensor chip 11 is attached to the housing 9 via the fixed base 2. The fixing base 2 is made of ceramics (for example, SiC) having a linear expansion coefficient approximate to that of silicon in consideration of electrical insulation with the composite function type pressure sensor chip 11 and reduction of thermal strain due to a difference in linear expansion coefficient with the housing 9. It is desirable to use Pyrex glass.
The fixing base 2 may be a silicon carbide sintered body or borosilicate glass.
[0037]
The fixing base 2 and the sensor chip 11 are joined via a joining member 29. The joining member 29 is made of oxide solder such as low melting point glass or metal solder, and is fused at the time of assembly. In addition, an Au—Si alloy layer or an Au thin film is formed in advance on the fixing table 2 or the sensor chip 11 by sputtering or vapor deposition, and is fused at the time of assembly to fix the fixing table 2 and the sensor chip 11. It is also possible to employ a method of joining and anodic bonding. Furthermore, it is also possible to join the fixing base 2 and the sensor chip 11 using an organic or inorganic binder.
[0038]
The bonding member 29 is sandwiched between the fixed base 2 and the sensor chip 11, and the surface of the sensor chip 11 on which the resistance elements 111 to 114 are formed and one surface of the fixed base 2 are arranged to face each other. The sensor chip 11 and the fixing base 2 are joined.
[0039]
Further, at the time of joining, as will be described later, the connection pad terminals a to j of the sensor chip 11 and the conductor 33 and the conductive pin 41 provided on the fixing base 2 are also joined, so that electrical connection can be achieved.
[0040]
On the other hand, a groove 22 serving as a comparative measurement chamber for comparing the fluid pressure to be measured in the process with the reference pressure is formed on the surface of the fixed base 2 where the sensor chip 11 is joined. The sensor chip 11 and the base 2 are joined through a joining member 29 in a vacuum atmosphere, and when the joining is completed, the through hole 35 is sealed, so that a vacuum reference pressure chamber can be formed by the groove 22. .
[0041]
Further, if the shape of the groove 22 is configured to penetrate the surface side opposite to the joint surface with the sensor chip 11 through the through-hole 35 and be released to the atmosphere when the joint between the sensor chip 11 and the base 2 is completed, An atmospheric pressure reference chamber can be formed.
[0042]
A first electrode 116 is formed on the surface of the diaphragm 110 facing the fixed base 2, and a second electrode 117 is formed on the surface of the fixed base 2 with respect to the first electrode 116. The second electrode 117 is filled in a hole formed in the fixed base 2 and connected to the conductor 34 and the conductive pin 41.
[0043]
Further, on the surface of the sensor chip 11 on the side in contact with the fluid to be measured, an oxide film, tetrafluoroethylene, high corrosion resistance gold (Au), platinum (Pt), Teflon, or the like according to the fluid to be measured The thin film 121 is formed by sputtering or vapor deposition.
[0044]
The thin film 121 can be easily formed even after the sensor chip 11 and the fixing base 2 are joined. Thereby, the thin film 121 can be formed not only on the sensor chip 11 but also on the surface of the fixed base 2.
[0045]
Therefore, the fluid pressure to be measured in the process is transmitted to the groove 120 of the sensor chip 11, and the reference pressure is transmitted to the surface side where the resistance elements 111 to 114 of the sensor chip 11 are arranged. Pressure acts on the diaphragm 110 surface, and this differential pressure can be converted into an electrical signal.
[0046]
At this time, since the arrangement surface side of the resistance elements 111 to 114 of the sensor chip 11 does not come into contact with the fluid to be measured, the conventionally used metal diaphragm and the sealed liquid sealed for pressure transmission are not used. It becomes absolutely unnecessary. In addition, 9 and 91 are a housing, 10 is a flange, 101 is a pressure application port.
[0047]
The pressure and temperature signals from the multi-function pressure sensor chip 11 are obtained by injecting the conductor 33 into the connection pad terminals a to j of the sensor chip 11 and the fine holes provided in the fixing base 2 and fixing the conductive pins. 41 to the outside. In general, the conductive pins 41 are formed when the fixing base 2 is manufactured.
[0048]
By the way, in the first embodiment of the present invention, as the thickness of the pressure sensitive diaphragm 110 of the multi-function pressure sensor chip 11 is reduced, the measured pressure can be measured to a lower pressure range.
[0049]
However, if the pressure-sensitive diaphragm 110 is made thinner than necessary, the nonlinearity in the pressure-voltage relationship becomes large and correction becomes difficult. This can be counteracted by setting the diaphragm 110 to the limit value of its thickness and increasing the diameter of the diaphragm 110, but this cannot achieve cost reduction and compactness.
[0050]
For this reason, in the first embodiment of the present invention, in order to extend the measurement range to a lower pressure range, another pressure sensor is arranged.
As another sensor, a sensor that detects the pressure by measuring a change in thermal conductivity and a sensor that measures the pressure using ionization are provided on the fixed base 2. However, in the first embodiment, a sensor using a change in thermal conductivity is employed.
[0051]
As a sensor using a change in thermal conductivity, a temperature change of resistance caused by a pressure change can be detected by the resistance change. A thermistor having a large resistance temperature coefficient is used as the resistance element.
[0052]
The thermistor is a metal oxide semiconductor, and has a negative resistance coefficient that is about 10 to 20 times larger than that of a metal.
[0053]
As shown in FIGS. 1 and 3, the thermistor 118 is formed on the surface of the fixed base 2 on the side to be joined with the sensor chip 11 by a thick film technique or a vapor deposition technique. The thermistor 118 is connected to a tungsten or platinum pad 119 in order to maximize the heat radiating surface area of the element and reduce the heat loss of the lead wire 1181.
[0054]
Further, a resistor RTH (shown in FIG. 6) composed of these elements 118, 1181, and 119 is covered with a cover 120A in order to stabilize heat. The cover 120A is joined to the fixing base 2 by the joining member 12 similar to the joining member 29 (FIGS. 3 and 4 (cross-sectional view along the line AA in FIG. 3), FIG. 5 (B in FIG. 3). (See cross-sectional view along line B)).
[0055]
As shown in FIGS. 4 and 5, the pad 119 contacts and is fixed to the conductor 33 filled in the hole 32 formed in the fixing base 2, and is also connected to the conductive pin 41.
[0056]
The resistance change of the resistance elements 111 to 114 (Rg1 to Rg4) and 118 (RTH) can be detected by taking out the unbalanced voltages (EPV1 and EPV2) with a bridge circuit as shown in FIG. Other resistors 1111, 1112, 1113 (R 0) that form a bridge circuit together with the thermistor 118 are arranged on the substrate 42 of the signal processing unit 190 (FIG. 1).
[0057]
The relationship between the output of the thermistor 118 and the pressure can be easily based on this information if the relationship between the output and temperature is collected in advance as information and stored in the memory 739 (shown in FIG. 7). Therefore, accurate pressure can be detected.
[0058]
In the configuration described above, the measurement area is 10^-5-10^-2It is possible to measure the pressure of Torr, and the measurement range is wide. Further, in order to ensure the lifetime of the thermistor 118 and the resistors 1111 to 1113, the thermistor 118 and the resistors 1111 to 1113 are configured to operate only when necessary.
[0059]
That is, when necessary, the bridge SW is operated by closing the switch SW (shown in FIG. 6) disposed between the voltage source E and the bridge circuit including the thermistor 118 and the like. Thereby, the temperature rise time of the resistor is minimized.
[0060]
This switch SW is disposed in the signal processing unit, and operates according to a command from the microcomputer 730 when the capacitance between the first electrode 116 and the second electrode 117 formed on the sensor chip 11 reaches a specified value. . This specified value is set by determining the distance between the first electrode 116 and the second electrode 117 corresponding to the measured pressure sensitivity of the sensor chip 11.
[0061]
By the way, the resistance elements 111 to 114 on the pressure sensitive diaphragm 110 are subjected to distortion caused by the pressure difference between the surface of the diaphragm 110 and the groove 120, and the resistance changes due to the piezoresistive effect, so that the signal can be taken out.
[0062]
However, even when the pressure applied to both surfaces of the pressure-sensitive diaphragm 110 is equal, or even when the temperature changes, these resistance elements 111 to 114 change their outputs in response to them.
[0063]
The zero point change at the time of temperature change is mainly because the resistance values of the resistance elements 111 to 114 and the resistance values of the resistance elements 111 to 114 are functions of temperature. Therefore, the relationship between the output signal of the temperature sensor 115 and the output signals of the pressure sensors 111 to 114 can be clearly related, and if this relationship is stored in advance, compensation is easy.
[0064]
That is, if the relationship between the change in the zero point of the pressure sensor and the temperature is collected as information in advance and stored in the memory 739 (FIG. 7), compensation can be made based on this information.
[0065]
The output signal from the semiconductor composite pressure sensor 11 is transmitted to the circuit of the circuit board 42 of the signal processing unit 190 via the flexible printed board 4 and the connector 41. From the cable 200 to which the final signal information is connected, for example, as a 4 to 20 mA analog constant current signal, or as a signal in which a rectangular digital signal is superimposed on a 4 to 20 mA analog constant current signal, or a digital constant current It is converted into a signal and output.
[0066]
Next, the signal processing unit 190 will be described in detail. Signals from the sensor unit sets 100A and 100B are supplied to the signal processing circuit on the substrate 42 via the connector 41 and are subjected to signal processing. Furthermore, the power supply circuit for driving the signal processing circuit on the substrate 42 is housed in a cylindrical signal processing unit case 92 made of SUS or aluminum die-casting, and inserted into the wiring connection port 300. The power supply circuit and an external power supply are connected via a two-wire transmission line.
The signal processing unit case 92 is mechanically coupled to the housing 91 and can be configured to be compact, save material, and increase rigidity.
[0067]
FIG. 7 is a schematic configuration diagram of a signal processing circuit of the dry type pressure detection device according to the first embodiment of the present invention. In FIG. 7, output signals from the pressure sensors 111 to 114, the temperature sensor 115, and the thermistor (vacuum sensor) 118 are selectively captured by a multiplexer (MPX) 731.
[0068]
The sensor signal captured by the multiplexer 731 is amplified by a programmable gain amplifier (PGA) 733 and converted to a digital signal by an A / D converter 734. The signal converted into a digital signal by the A / D converter 734 is supplied to a microprocessor (MPU) 730.
[0069]
In the memory 739 (EEPROM), the characteristic data of the pressure sensors 111 to 114 and the temperature sensor 115 are stored in advance, and the microprocessor 730 uses these characteristic data to store the pressure sensors 111 to 114 and the temperature sensor 115. By correcting and calculating the output signal, a highly accurate pressure signal value and temperature signal value are calculated.
[0070]
The calculation result of the microprocessor 730 is converted into a normal analog signal via a D / A converter 737 and a V / I converter 738, and is a computer that is a higher-level control device as a DC 4-20 mA DC current signal. And can be transmitted to a signal converter. The information is displayed on the internal display 736 or the external display 737.
[0071]
Further, in the example shown in FIG. 7, it is possible to superimpose information on the process state obtained by the multi-function pressure sensor 11 as a digital signal on a DC current of 4 to 20 mA and transmit it to an external host control device or the like. is there.
[0072]
Furthermore, although not shown, it is also possible to transmit process information to an external host control device or the like using a digital signal generated by a direct current from a signal processing circuit.
[0073]
In a communication method in which a digital signal is superimposed on a direct current signal or a communication method in which a digital signal is used to communicate with a monitoring control device provided outside, a digital I / O circuit housed in a V / I converter 738 is used. Displays information about the process status on, for example, an operator's console or handheld terminal.
[0074]
Then, the configuration such as setting, changing, output adjustment, input / output monitoring, self-diagnosis, etc. of parameters such as the measurement range can be performed from these handheld terminals.
[0075]
Further, the microprocessor 730 determines whether or not the first electrode 116 and the second electrode 117 are in contact with each other. If they are in contact with each other, the display 736 or 737 is displayed and an alarm is provided. it can.
[0076]
That is, when the pressure of the fluid to be measured exceeds a specified value, the distance for the first electrode 116 and the second electrode 117 to contact each other is calculated in advance through experiments or the like. A second electrode 117 is disposed. If comprised in this way, when the fluid to be measured generates abnormal pressure, it is possible to warn it.
[0077]
As described above, according to the first embodiment of the present invention, the semiconductor pressure sensor 11 in which the thin film 121 made of Au, Pt, or Teflon having high corrosion resistance is formed on the surface of the semiconductor pressure sensor 11 is formed. Since the fluid to be measured is directly brought into contact with the diaphragm 110 and the pressure of the fluid to be measured is applied, the sealed liquid and the sealed liquid, which are conventionally required, are isolated from the fluid to be measured. The diaphragm for this is no longer necessary.
Therefore, while having a simple configuration, a high vacuum region (1 × 10 10^-5  It is possible to realize a dry-type pressure detection device that can also measure the pressure in a vacuum region below Torr.
[0078]
In the first embodiment, the pressure sensor on the diaphragm 110 is arranged separately from a sensor 118 that detects the pressure by measuring a change in thermal conductivity, and thus is lower. Measurement is possible up to the pressure range.
[0079]
In the first embodiment, since the sensor chip 11 is configured to contact the fluid to be measured, instead of the sensor 118 that measures the above-described change in thermal conductivity, the pressure is applied using ionization. A sensor of the type to be measured, that is, a sensor that uses the relationship between the generated ions of the fluid to be measured and the pressure can be provided on the fixed base 2. In this case, similarly to the sensor 118, it is possible to measure up to a lower pressure region, and it is possible to further improve the measurement accuracy.
[0080]
The thermistor 118 and the resistors 1111 to 1113 are configured to operate only when necessary. That is, when necessary, the bridge SW is operated by closing the switch SW disposed between the voltage source E and the bridge circuit including the thermistor 118 and the like.
[0081]
Thereby, the thermistor 118 and the resistors 1111 to 1113 can be extended in life, and the temperature rise time of the resistor can be minimized.
[0082]
Further, the groove 22 functions as a mechanical stopper that prevents excessive deformation of the pressure-sensitive diaphragm 110 even when the pressure of the process fluid exceeds the specification for some reason. The depth of the groove 22 is determined in accordance with the measurement pressure specifications of the sensor, and is generally set with a diaphragm deformation amount of about 1.5 to 2 times the full scale.
For this reason, even if an excessive pressure is applied to the diaphragm 110, the diaphragm 110 is not damaged, so that the reliability of the pressure sensor can be improved.
[0083]
In the first embodiment described above, the diaphragm 110 of the sensor having a pressure sensitive element is shown to have a substantially uniform thickness. However, the present invention is not limited to this shape and is not limited to this. Even if various shapes that improve the linearity are adopted, the same effect can be obtained, and a dry type pressure sensor with improved measurement accuracy can be realized.
[0084]
FIG. 8 is a schematic cross-sectional view of an absolute pressure type pressure detecting device according to a second embodiment of the present invention, and the diaphragm 110 is an example in which a rigid body portion 130 is formed at the center thereof. The rigid body portion 130 has a thickness substantially equal to the outer peripheral portion (support portion) of the diaphragm 110 in the sensor chip 11. Since other configurations are the same as those of the first embodiment, description thereof will be omitted.
[0085]
In the second embodiment, the same effect as that of the first embodiment can be obtained, and the non-linearity of the output characteristic from the resistance element arranged in the diaphragm 110 can be improved. A dry type pressure sensor with improved accuracy can be realized.
[0086]
In the first and second embodiments described above, either the thermal conductivity type sensor or the ionization type sensor is arranged as a pressure sensor separate from the pressure sensors 111 to 114. Two sensors, a thermal conductivity type sensor and an ionization type sensor, can be arranged, and the measurement range can be further expanded, and a dry type pressure sensor with improved accuracy can be realized.
[0087]
【The invention's effect】
Since the present invention is configured as described above, it has the following effects. Since the pressure is transmitted directly in contact with the fluid to be measured, the surface opposite to the surface on which the pressure detection element of the semiconductor pressure sensor for detecting the pressure of the fluid to be measured is disposed, The filled liquid can be omitted, the assemblability is excellent, the entire detection device is miniaturized and the number of components is small, the reliability of the device is improved and the maintenance can be easily performed.
[0088]
In addition, since there is no encapsulated liquid, restrictions on the range of use can be eliminated, the measurement area can be expanded, and labor saving of the instrument can be achieved.
In addition, the detection device itself can be made very compact, and it has an economical advantage. Furthermore, the system can be easily replaced, and is very easy to use during maintenance and inspection.
[0089]
Furthermore, according to the pressure detection device of the present invention, the reliability of the equipment itself can be improved, so that the maintenance period of equipment or the periodic inspection period of the plant can be extended.
[0090]
As described above, the pressure detection device of the present invention is excellent in environmental resistance, is very easy to use during maintenance and inspection, and can reduce the cost of implementing the plant. Furthermore, since the equipment itself can be configured to be stable and highly reliable, the operation efficiency of the plant can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an absolute pressure type dry type pressure detection apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a sensor section shown in FIG.
FIG. 3 is a schematic configuration diagram of the fixed base shown in FIG. 1;
4 is a cross-sectional view taken along line AA in FIG.
5 is a cross-sectional view taken along line BB in FIG. 3. FIG.
FIG. 6 is an equivalent circuit diagram of the sensor in the example of FIG.
7 is a schematic configuration diagram of a signal processing unit in the example of FIG.
FIG. 8 is a schematic cross-sectional view of an absolute pressure type dry type pressure detection apparatus according to a second embodiment of the present invention.
FIG. 9 is a schematic sectional view of an example of a conventional pressure sensor.
FIG. 10 is an equivalent circuit diagram of the sensor in the example of FIG.
[Explanation of symbols]
2 fixed base
4 Flexible printed circuit boards
9 Housing
10 Process flange
11 Pressure sensor
12, 29 Bonding material
22 Fixed table groove (reference room)
32, 35 fine holes
33, 34 Conductor material
41 Conductive pin
42 Circuit board
91 Housing
92 Signal processor case
100A, 100B sensor assembly
101 Pressure application port
110 Diaphragm
111-114 Pressure sensitive element
115 Temperature sensor
116 1st electrode
117 Second electrode
118 Thermistor
119 electrode
120 Sensor recess
120A cover
121 Protective film
130 Rigid body
190 Signal processor
200 cables
731 Multiplexer
733 PGA
730 MPU
737 D / A converter
738 V / I converter
736, 737 Display
739 memory
1111 to 1113 resistors
1181 Lead wire

Claims (9)

A semiconductor pressure sensor that combines a pressure detection element that detects the pressure of the fluid to be measured, and a temperature detection element that detects the temperature, and a pressure receiving portion that includes a fixed base that fixes the semiconductor pressure sensor, and is connected to the pressure receiving portion. In a dry type pressure detection device comprising a signal processing unit for processing a detection signal from a semiconductor sensor,
The semiconductor pressure sensor has a thin portion and a thick portion by forming a recess in the central portion of one surface, and a plurality of pressure detection elements are disposed on the thin portion on the opposite surface where the recess is formed. And a plurality of connection terminals connected to the pressure detection element are arranged on the thick part,
The fixed base, a concave portion is formed in the center portion, and around the concave portion provided corresponding to the positions of the connection terminals, between the semiconductor pressure sensor opposite from the surface facing to the signal processing unit on the surface And a plurality of lead terminals connected to the signal processing unit are formed,
The surface on which the concave portion of the fixing base is formed and the surface on which the pressure detection element of the semiconductor pressure sensor is disposed are joined so that the connection terminal and the extraction electrode are aligned, and the pressure by the concave portion of the fixing base is obtained by the joining. Forming a reference chamber,
An oxide film is formed on both the sensor and the fixing table on the concave surface of the semiconductor pressure sensor and the surface of the fixing table that contacts the fluid to be measured.
A dry type pressure detecting device, wherein the pressure transmitted by the fluid to be measured contacting the recess of the semiconductor pressure sensor is detected by the pressure detecting element. 2. The dry type pressure detecting device according to claim 1, wherein a tetrafluoroethylene film is formed instead of the oxide film. 3. The dry type pressure detecting device according to claim 2, wherein a protective film made of gold is formed instead of the oxide film. 3. The dry type pressure detecting device according to claim 2, wherein a protective film made of platinum is formed instead of the oxide film. 3. The dry type pressure detecting device according to claim 2, wherein the space formed by the concave portion of the fixed base and the semiconductor pressure sensor forms a vacuum reference pressure chamber sealed from the surroundings. Pressure type dry type pressure detector. 6. The dry type pressure detection device according to claim 5, wherein at least one vacuum is formed on a surface of the fixed base to which the semiconductor pressure sensor is bonded, and in a region other than the region where the semiconductor pressure sensor is bonded. An absolute pressure type dry type pressure detecting device, wherein a sensor for measurement is arranged. 7. The dry type pressure detection device according to claim 6, wherein the vacuum measurement sensor is a sensor that utilizes the fact that heat loss due to heat conduction of the fluid to be measured changes with the pressure of the fluid to be measured. Absolute pressure type dry type pressure detector. 7. The dry type pressure detection apparatus according to claim 6, wherein the vacuum measurement sensor is a sensor that detects the number of generated ions of the fluid to be measured, and controls the pressure of the fluid to be measured according to the number of detected ions. An absolute pressure dry type pressure detector characterized by measuring. 7. The dry type pressure detection apparatus according to claim 6, wherein a first electrode is disposed on a surface of the semiconductor pressure sensor on which the pressure detection element is disposed, and a concave portion of the fixed base is opposed to the first electrode. An absolute pressure type dry type pressure detecting device, wherein a second electrode is disposed, and the signal processing unit detects a capacitance value between the first electrode and the second electrode.

Images