JP3044583B2 - Semiconductor fluid sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor fluid sensor for electrically detecting a change in gas flow by a semiconductor sensor element formed by micromachining using a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, as a fluid sensor for detecting a change in gas flow, for example, as shown in FIG. 6, a diaphragm type pump 24 is driven to circulate a gas sealed in a casing 25 while circulating the gas. A gas is ejected from a nozzle hole 27 in the main body 26 to generate a gas flow in a gas passage 29 in which heat wires 281 and 282 including a pair of heat-sensitive resistance elements are provided. Each heat wire 28
There is a gas rate sensor that detects the direction and magnitude of the angular velocity acting on the sensor by detecting the change in thermal resistance when the 1,282 is biased to the gas flow (Japanese Patent Publication No. 64-4623). Reference).

In such a fluid sensor such as a gas rate sensor, since a change in gas flow is electrically detected by a change in thermal resistance caused by a heat wire, a change in an external temperature is detected. The fluid sensor is installed inside the thermostat 30 so that the fluid sensor is heated to a constant temperature by the heater wires 32 wound around the casing 25 and the support 31 so that the fluid sensor is not affected by the temperature. I keep it.

In FIG. 6, reference numeral 33 denotes a circuit board on which a sensor circuit and an amplifier circuit for amplifying the sensor output signal are mounted.

In such a conventional fluid sensor,
In addition to the main sensor rest 26, the casing 25 and the sensor body 2
6, a gas circulation path 34 is separately formed.

[0006]

The problem to be solved is that in a fluid sensor such as a gas rate sensor for detecting a change in gas flow, a gas circulation path is required in addition to the sensor body, so that the whole becomes large. Is to put it.

[0007] The large size of the fluid sensor makes it difficult to stably maintain the temperature of the fluid sensor.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a gas flow is changed by a micromachining process using a semiconductor substrate while effectively reducing the size by not separately providing a gas circulation path other than the sensor body. A semiconductor sensor element as a sensor main body for detecting the temperature, mounts the semiconductor sensor element on a substrate together with a micropump, stores the substrate together with a heater in a gas-sealed package, and drives the package by driving the micropump A gas flow is generated in the semiconductor sensor element while circulating the gas in an open loop inside the inside, so that the fluid sensor can be made into a small package and the temperature can be easily and stably maintained. And

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described for the case where a gas rate sensor is used as a fluid sensor.

In a semiconductor fluid sensor according to the present invention, as shown in FIG. 1, a semiconductor sensor element 1 for detecting a change in gas flow, a micropump 2 for generating a gas flow in the semiconductor sensor element 1, A sensor circuit and an IC chip 3 constituting an amplifier circuit for amplifying the sensor output signal are mounted on a predetermined position on a ceramic substrate 4 on which a wiring pattern is formed in advance, and the ceramic substrate 4 is mounted together with the heater 5 with helium or helium. The semiconductor sensor element is housed in a can package 7 in which a gas such as nitrogen is sealed, and is circulated in an open loop by driving the micropump 2 in the can package 7 maintained at a constant temperature by heating by the heater 5. 1 to generate a gas flow.

Here, a heat insulating material 6 such as a glass plate is placed on a base 71 of the can package 7 with hermetic terminals 8.
And a heater 5 composed of a ceramic heater (a heater wire embedded in a ceramic substrate) or the like is bonded on the heat insulating material 6, and the ceramic substrate 4 is further bonded and mounted on the heater 5. I have to.

The terminal provided on the wiring portion of the ceramic substrate 4, the terminal of the heater 5, and the can package 7
After connecting the corresponding hermetic terminals 8 by wire bonding, the cap 72 of the can package 7 is put on the base 71 in a gas atmosphere, and the two are sealed by bonding or the like to prevent gas leakage. Is stopped.

At this time, it is necessary to sufficiently perform the gas purging process in the can package 7. Further, if necessary, the gas in the can package 7 is raised or reduced in pressure above the atmospheric pressure.

Although the ceramic substrate 4 is placed on the heater 5 here, a heater wire may be embedded inside the ceramic substrate 4 without separately providing the heater 5.

The IC chip 3 can incorporate a driving constant current circuit or a constant voltage circuit in addition to the sensor circuit and the amplifier circuit for amplifying the sensor output signal.

FIGS. 2 to 4 show one configuration example of a semiconductor sensor element 1 as a sensor body in a gas rate sensor formed by micromachining using a semiconductor substrate.

Here, a lower semiconductor substrate 11 and an upper semiconductor substrate 12 in which a half hole 91 for forming a nozzle hole 9 and a half groove 101 for forming a gas passage 10 connected thereto are formed in a semiconductor substrate by etching. The nozzle holes 9 and the gas passages 1 are overlapped so that the respective half holes 91 and the half grooves 101 are attached to each other and bonded together.
0 is formed.

Further, the lower semiconductor substrate 11 is etched to form a bridge portion 13 extending over the gas passage 10. On the upper surface of the bridge portion 13, a heat wire material such as platinum is deposited, and is etched and trimmed. As a result, a pair of heat wires 141 and 142 are formed in a pattern, and electrode portions 15 are similarly formed on both sides thereof.

As the micro pump 2, for example, FIG.
As shown in FIG. 2, a semiconductor device in which a diaphragm 19, a suction hole 20, a suction valve 21, a discharge hole 22, and a discharge valve 23 are formed by etching a semiconductor substrate 17, 18 using a piezo element 16 as a driving source is used. .

Then, the micropump 2 is coupled to the semiconductor sensor element 1 such that the discharge hole 22 is connected to the nozzle hole 9 in the semiconductor sensor element 1.

The micro pump 2 can be formed integrally with the semiconductor sensor element 1.

The sensor circuit incorporated in the IC chip 3 includes a pair of heat wires 141 in the semiconductor sensor element 1 for electrically detecting a deflection state of a gas flow when an angular velocity acts. , 142 and a reference resistor, a circuit portion excluding the heat wires 141 and 142 in the resistance bridge circuit.

In the semiconductor fluid sensor according to the present invention configured as described above, the micropump 2 is operated while the heater 5 is heated by an external drive circuit to maintain the inside of the can package 7 at a constant temperature. The semiconductor sensor element 1 is driven to generate a gas flow while circulating the gas in an open loop in the can package 7.

Thus, according to the present invention, there is no need to separately provide a gas circulation path other than the sensor main body, the structure of the semiconductor fluid sensor is simplified, and the miniaturization of the semiconductor fluid sensor can be effectively achieved.

By using a simple heater 5, the temperature inside the can package 7 can be easily and stably maintained, and the temperature inside the can package 7 can be raised to a predetermined temperature in a short time. By performing temperature control with good responsiveness, a change in gas flow can be accurately detected without being affected by a change in external temperature.

According to the present invention, the can package 7
A semiconductor sensor element 1 and a sensor circuit, an amplifier circuit,
Since the IC chip 3 in which the driving constant current circuit or the constant voltage circuit is integrated is incorporated and the sensor output signal can be amplified from the sensor driving inside the can package 7, the temperature drift problem , And less susceptible to external electrical noise.

Further, if a gas is sealed in the sensor element itself as in the prior art, the breaking strength is significantly reduced and it is necessary to pay attention to the handling during the assembly work. In this regard, according to the present invention, Since no gas is sealed in the semiconductor sensor element 1 itself, the assembling work becomes easy.

[0028]

As described above, in the semiconductor fluid sensor according to the present invention, a micromachining process using a semiconductor substrate is performed while effectively reducing the size by not separately providing a gas circulation path other than the sensor body. Forming a semiconductor sensor element as a sensor body for detecting a change in gas flow, mounting the semiconductor sensor element on a substrate together with a micropump, storing the substrate together with a heater in a gas-sealed package, The pump is driven to generate a gas flow in the semiconductor sensor element while circulating the gas in the package in an open loop, so that the fluid sensor can be miniaturized and the temperature can be easily and stably maintained. This is advantageous in that it is resistant to noise and can accurately detect changes in gas flow.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing one embodiment of a semiconductor fluid sensor according to the present invention.

FIG. 2 is a perspective view of the semiconductor sensor element according to the embodiment.

FIG. 3 is a plan view of a lower semiconductor substrate of the semiconductor sensor element.

FIG. 4 is a sectional view taken along line AA of FIG. 2;

FIG. 5 is a front sectional view showing one configuration example of a micropump.

FIG. 6 is a front sectional view showing a conventional gas rate sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor sensor element 2 Micro pump 3 IC chip 4 Ceramic substrate 5 Heater 6 Insulation material 7 Can package

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Claims (2)

(57) [Claims] A semiconductor sensor element for detecting a change in gas flow and a micropump are mounted on a substrate, and the substrate is housed together with a heater in a gas-sealed package .
Gas is circulated in the package by driving the micro pump
A semiconductor fluid sensor configured to generate a gas flow in the semiconductor sensor element . To 2. A semiconductor sensor device and the substrate and is mounted micropump according of claims 1, characterized in Furudo the IC chip is mounted that constitutes the amplifier circuit for amplifying the sensor circuit and the sensor output signal Semiconductor fluid sensor.