JP2004191343A - Gas type rate sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas type rate sensor which produces always a stable gas flow in a sensor body and keeps a coupling precision between the sensor body and a pump, and no influence due to a temperature change is recognized. <P>SOLUTION: A gas type rate sensor consists of a nozzle hole, a gas flow path, a sensor bridge crossing the gas flow path, a gas supply port connecting to the nozzle hole at the upper part of the gas flow path, the sensor body forming each gas exhaust port at the rear part of the gas flow path. The gas type rate sensor is characterized that the pump is integrally constituted with a first substrate and a second substrate, wherein the first substrate mounted on the sensor body comprising: a vibration plate having a gas passing hole at the end which is vibrated by a piezoelectric element mounting on the vibration plate; a pump intake and exhaust chamber having an intake port at the other side of the gas passing hole, and the second substrate forming a pump back pressure chamber is mounted on the first substrate and both the first substrate and the second substrate are connected. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a gas type rate sensor that electrically detects a deflection state of a gas flow according to an angular velocity acting on a sensor main body.
[0002]
[Prior art]
In general, in a gas type rate sensor, a gas is ejected from a nozzle hole in a sensor body toward a heat sensor composed of thermosensitive resistance elements provided on the left and right sides in a gas passage by a pump, and the sensor body is externally supplied. When the gas flow flowing in the gas passage is deflected to the left and right due to the angular velocity motion applied to the heat sensor, it takes out an electric signal according to the change in the resistance value generated in the heat sensor and acts on the sensor body at that time The direction and magnitude of the present angular velocity are detected.
[0003]
As this type of gas type rate sensor, a sensor body composed of a nozzle hole, a gas passage, and a heat sensor provided in the gas passage is an ultra-small type formed by micromachining a semiconductor substrate using IC manufacturing technology. Has been developed (see JP-A-5-2027).
[0004]
As shown in FIGS. 1 to 3, the sensor body of the gas type rate sensor is such that a small groove 40 for a nozzle hole, a half groove 51 for a gas passage, and a sensor bridge 6 for a gas passage etch a semiconductor substrate. The gas supply port 7 leading to the small groove 40 for the nozzle hole is provided on the upper surface of the lower substrate 1 and the gas supply port 7 connected to the small groove 40 for the nozzle hole. The nozzle holes 4 and the gas passages 5 are formed by superimposing the upper substrate 2 formed thereon and bonding them together.
[0005]
On the upper surface of the sensor bridge 6, a pair of left and right heat sensors 91 and 92 made of a heat-sensitive material such as platinum are patterned. In the drawing, reference numeral 10 denotes each electrode of the heat sensors 91 and 92.
[0006]
Then, as shown in FIG. 4, the gas is sent from the gas supply port 7 of the sensor body 11 using a piezoelectric pump 12 separately manufactured by metal working, and the gas flows into the gas passage 5 from the nozzle hole 4. Is caused.
[0007]
However, when the sensor main body 11 is microscopic by micromachining, the gas flow ejected from the nozzle hole 4 into the gas passage 5 by the pump 12 leads to the detection accuracy of the angular velocity in the sensor main body 11.
[0008]
At this time, if the pump 12 is assembled to the sensor main body 11 so that the gas supply port 7 of the sensor main body 11 and the discharge port 13 of the pump 12 are directly connected, the difference in the thermal expansion coefficient due to the temperature caused by the difference in the materials of the two. For example, it is difficult to maintain the joining accuracy of the two, such as displacement, and if the joining positions of the two are displaced, the gas flow will be disturbed in the sensor body 11.
[0009]
For this reason, conventionally, as shown in FIG. 4, the sensor body 11 and the pump 12 are each fixed to a stay (not shown), and then the nozzle 14 is attached to the gas supply port 7 of the sensor body 11, so that the pump The tube 15 connects the discharge port 13 and the nozzle 14.
[0010]
However, if such a connecting means between the sensor main body 11 and the pump 12 is employed, the number of parts is increased, the workability of assembling is deteriorated, and the entire apparatus is enlarged. In addition, the displacement of the joining position between the sensor body 11 and the pump 12 cannot be completely eliminated.
[0011]
[Problems to be solved by the invention]
The problem to be solved is that, when assembling a pump manufactured by metal processing separately to a sensor body manufactured by micro-machining processing of a semiconductor substrate, it is difficult to maintain the coupling accuracy by directly connecting the two, and If a connecting member such as a tube for a joint is used, the workability of assembling is deteriorated, and the whole apparatus is enlarged.
[0012]
[Means for Solving the Problems]
In the gas type rate sensor according to the present invention, the pump manufactured by the micromachining of the semiconductor substrate is also integrally attached to the sensor body manufactured by the micromachining of the semiconductor substrate, and the coupling accuracy of the two is maintained. In order to always generate a stable gas flow in the sensor main body, a vibration plate is formed, which is overlapped and joined on the sensor main body, vibrated by the piezoelectric element on the upper surface, and has a vent hole on one side. A first substrate forming a pump suction / exhaust chamber provided with a suction port on a side opposite to the ventilation hole, and a second substrate forming a pump back pressure chamber by being overlapped and joined on the first substrate Thus, the pump is constituted by the above.
[0013]
【Example】
In the gas type rate sensor according to the present invention, as shown in FIG. 5, a pump 16 also manufactured by micromachining of a semiconductor substrate is integrally formed on a sensor main body 11 manufactured by micromachining of a semiconductor substrate. I try to assemble it.
[0014]
As in the conventional case, the sensor body 11 is formed by joining the lower substrate 1 and the upper substrate 2 to form the nozzle holes 4, the gas passages 5, the sensor bridge 6 having the heat sensors 91 and 92 formed on the upper surface thereof in a pattern, A gas supply port 7 and a gas discharge port 8 are formed.
[0015]
As the pump 16, a diaphragm 18 having an air hole 17 formed on one side is integrally formed on the upper substrate 2 of the sensor body 11 and joined thereto, and suction is performed on the opposite side to the air hole 17. It comprises a first substrate 21 forming a pump suction / exhaust chamber PA provided with a port 19, and a second substrate 22 overlapping and joined on the first substrate 21 to form a pump back pressure chamber PB. ing. A piezoelectric element 20 is bonded or formed on the diaphragm 18.
[0016]
In such a configuration, the pump operation is performed as follows.
[0017]
First, as shown in FIG. 6, when a positive voltage is applied to the piezoelectric element 20 and the vibration plate 18 bends upward, the pump back pressure chamber PB becomes a positive pressure, and the gas in that chamber passes through the vent 17. It is discharged and sent to the gas supply port 7 of the sensor body 11. At this time, the pump suction / exhaust chamber PA becomes a negative pressure and sucks gas from the suction port 19. In the figure, arrows indicate the flow of gas.
[0018]
Next, as shown in FIG. 7, when a negative voltage is applied to the piezoelectric element 20 and the diaphragm 18 bends downward, the pump suction / exhaust chamber PA becomes positive pressure and the pump back pressure chamber PB becomes negative pressure. Thus, the gas in the pump suction / exhaust chamber PA is sent into the pump back pressure chamber PB through the vent hole 17.
[0019]
At this time, the gas supplied from the gas supply port 7 is set so that the gas discharged by the pump operation is sufficiently taken into the gas supply port 7 of the sensor main body 11 and a stable gas flow can be generated from the nozzle hole 4 into the gas passage 5. The relative positioning is performed so that the ventilation hole 17 of the diaphragm 18 is concentrically located directly above, and the size and shape of the gas supply port 7 are optimally set.
[0020]
FIG. 8 shows another embodiment of the gas rate sensor according to the present invention.
[0021]
Here, the buffer chamber 3 is formed in front of the nozzle hole 4 as the sensor main body 11 ′, and the gas supplied from the pump 16 is supplied to the buffer chamber 3 by providing a gas supply port 7 above the buffer chamber 3. The gas is ejected from the nozzle hole 4 into the gas passage 5 after being buffered inside, so that a more stable gas flow is generated.
[0022]
FIGS. 9 and 10 show the lower substrate 1 'and the upper substrate 2' in the sensor main body 11 '. In this case, in particular, a half groove 31 for the buffer chamber is formed on the lower substrate 1 ', and a half groove 32 for the buffer chamber is formed on the upper substrate 1'.
[0023]
When mass-producing the gas type rate sensor according to the present invention, as shown in FIG. 11, a silicon wafer provided with a plurality of lower substrates 1 and a silicon wafer provided with a plurality of upper substrates 2 are bonded together in advance. A wafer polymer A on which a plurality of sensor bodies 11 are provided is prepared in advance. As shown in FIG. 12, a plurality of pumps 16 are arranged by bonding a silicon wafer on which a plurality of first substrates 21 are arranged in advance and a silicon wafer on which a plurality of second substrates 22 are arranged in advance. The prepared wafer polymer B is prepared in advance. After the wafer polymers A and B are bonded to each other in a predetermined manner, each component is diced to obtain a gas type rate in which the pump 16 is integrally mounted on the sensor body 11 as shown in FIG. Multiple sensors are obtained.
[0024]
When bonding the wafer polymers A and B, as shown in FIG. 13, alignment cross marks M1 are stamped at both ends of the wafer polymer A, and alignment marks are provided at both ends of the wafer polymer B. The alignment mark M2 is engraved. Then, as shown in FIG. 14, the wafer polymer A and the wafer polymer B are bonded together so that the cross mark M1 and the alignment mark M2 coincide with each other. Relative positioning can be easily and accurately performed such that the ventilation holes 17 come.
[0025]
【The invention's effect】
As described above, in the gas type rate sensor according to the present invention, the temperature change and the external change can be caused by integrally assembling the pump, which is also manufactured by micromachining the semiconductor substrate, with the sensor body manufactured by micromachining the semiconductor substrate. There is an advantage that a stable gas flow can always be generated in the sensor main body while maintaining the coupling accuracy of the two without being affected by vibrations applied from the sensor.
[0026]
According to the present invention, a gas type rate sensor having excellent workability and high accuracy can be easily obtained, which is most suitable for mass production.
[Brief description of the drawings]
FIG. 1 is a top view showing a lower semiconductor substrate of a sensor main body in a general gas rate sensor.
FIG. 2 is a bottom view showing an upper semiconductor substrate of a sensor main body in the gas rate sensor.
FIG. 3 is a side sectional view of a nozzle hole portion of a sensor main body in the gas rate sensor.
FIG. 4 is a front view showing a connection state between a conventional sensor main body and a pump.
FIG. 5 is a front sectional view showing one embodiment of a gas type rate sensor according to the present invention.
FIG. 6 is a front sectional view showing one operation state of the pump in the embodiment.
FIG. 7 is a front sectional view showing another operation state of the pump in the embodiment.
FIG. 8 is a front sectional view showing another embodiment of the gas type rate sensor according to the present invention.
FIG. 9 is a top view showing a lower substrate of a sensor main body in another embodiment.
FIG. 10 is a bottom view showing an upper substrate of a sensor main body in another embodiment.
FIG. 11 is a plan view showing a wafer polymer in which a plurality of sensor bodies are provided by bonding a silicon wafer provided with a plurality of lower substrates and a silicon wafer provided with a plurality of upper substrates. .
FIG. 12 is a plan view showing a wafer polymer provided with a plurality of pumps by bonding a silicon wafer provided with a plurality of first substrates and a silicon wafer provided with a plurality of second substrates. It is.
FIG. 13 is a plan view showing alignment marks respectively stamped on both wafer polymers when the wafer polymer on the sensor body side and the wafer polymer on the pump side are bonded together.
FIG. 14 is a view showing a matching state between a gas supply port in the sensor main body and a vent of the diaphragm in the pump when the wafer polymer on the sensor main body side and the wafer polymer on the pump side are bonded together.
[Explanation of symbols]
Reference Signs List 1 Lower substrate 2 Upper substrate 3 Buffer chamber 4 Nozzle hole 5 Gas passage 6 Sensor bridge 7 Gas supply port 8 Gas exhaust port 11 Sensor main body 12 Pump 16 Pump 17 Vent hole 18 Vibration plate 19 Suction port 20 Piezoelectric element 21 First Substrate 22 Second substrate PA Pump suction / exhaust chamber PB Pump back pressure chamber

Claims (3)

A gas type gas rate comprising a nozzle hole, a gas passage, a sensor bridge over the gas passage, a gas supply port connected to the nozzle hole at an upper portion of the gas passage, and a sensor body having a gas discharge port formed at the rear of the gas passage. In the sensor, a pump suction plate is formed so as to be overlapped on the sensor main body, vibrated by a piezoelectric element on the upper surface, formed with a diaphragm having a vent hole on one side, and provided with a suction port on the side opposite to the vent hole. A gas type rate sensor integrally provided with a pump including a first substrate forming an exhaust chamber and a second substrate forming a pump back pressure chamber, which is overlapped and joined on the first substrate. . 2. The gas type rate sensor according to claim 1, wherein a ventilation hole of a diaphragm of the pump is provided immediately above a gas supply port opened on an upper surface of the sensor main body. 2. A gas type rate sensor according to claim 1, wherein a buffer chamber is provided in front of the nozzle hole in the sensor main body, and a gas supply port is provided in the buffer chamber.

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