JP5286465B2 - Airflow sensor, tube with conductive film and airflow detection device used therefor - Google Patents

Description

The present invention relates to a thermal airflow sensor and the conductive film attached tube and airflow sensing device used therefor provided with a heater and a temperature sensor element can detect a change in air flow at high speed.

Conventionally, the present inventor has invented an “electric heater” (Japanese Patent Application No. 54-027559; Japanese Patent No. 1398241) which forms a heater by forming a resistor such as a platinum thin film on a thin film that has been suspended in the air. Currently, it is applied as a micro heater for flow sensors and vacuum sensors. Further, the applicant of the present invention uses a semiconductor diode as a heater “a heating diode temperature measuring device, an infrared temperature measuring device using the same, a flow rate measuring device, and a method for manufacturing a flow rate sensing unit” (Japanese Patent Application No. 2005-68266; 250736) was invented. Since the semiconductor diode can also be used as a temperature sensor, it has been proposed to use it as a heater / temperature sensor.

Conventionally, a vacuum chuck or vacuum pad was used to fix or transport an object, and vacuum tweezers were used for smaller objects. These are objects in which an object is sucked by vacuum suction or a negative pressure with respect to the ambient pressure, is captured by a suction cup, and conveyed as necessary, and it is necessary to know whether the object is reliably captured. To know whether an object has been reliably captured, a pressure sensor or airflow sensor has been attached to the vacuum pump side through a hose (flexible tube) from a suction section such as a vacuum pad, so that the change in airflow pressure can be detected. I was doing. However, in transporting microspheres, semiconductor chips, etc., it is important to determine how high-speed transport is possible, which leads to productivity. Pressure sensors, etc. are not only large but slow in operation, A pressure sensor or the like is attached to the vacuum pump for operation, and a time delay occurs in a tube having a large air resistance. As a result, an airflow sensor or a vacuum pad that responds at a high speed within 4 milliseconds cannot be provided. In addition, there was a sensor that cut a tube in the middle and attached to it, but there was a similar problem.
Japanese Patent No. 1398241 JP 2006-250736 A

The present invention has been made to solve the above-described problems, and a diode thermistor or the like is used as a temperature sensor. However, even if a heater is not used separately, a current is passed through the temperature sensor itself, and the heater is heated by self-heating by Joule heat. As a heater and temperature sensor element, this temperature sensor is also used as a heater for heating, and is ultra-compact that can be mounted in a minute space of a vacuum pad by MEMS technology. of providing a heater and a temperature sensor element, Ri mass producible der inexpensive, simple structure requires only two terminals, yet the heat conduction type of heater and the temperature sensor element is a high-precision thermal sensor with high sensitivity while providing, providing an air flow sensor for high sensitivity at high speed using the heater and the temperature sensor element, the air flow sensor to a vacuum pad of the high-speed response It is an object of the present invention to provide a compact and inexpensive airflow sensor that does not require complicated wire wires , and to provide an inexpensive and small airflow detection device.

In order to achieve the above object, an airflow sensor according to claim 1 of the present invention is formed on one surface side of a substrate in an airflow sensor mounted on an airflow detection device, and is thermally separated from the substrate. A temperature sensor formed on a thin film is a two-terminal heater / temperature sensor element that is also used as a heater by self-heating, a cover having a structure that does not contact the thin film portion is joined to the substrate, and the cover is attached to the cover. Is provided with at least one of two electrodes corresponding to the two terminals of the heater / temperature sensor element , and a pipe through which a gas flows. The pipe is connected to the heater / temperature sensor element. The heater and temperature sensor element that is miniaturized to the extent that it can be installed in the vicinity of the inlet of the pipe, and the fluctuation of the gas flow It was possible to detect an electric signal through the two wires from the heater and the temperature sensor element, it is characterized in.

The ultra-compact heater / temperature sensor element has a thin film thermally separated from a substrate such as a cantilever formed by MEMS technology, and this thin film is a heat sensor that detects changes in airflow using both a temperature sensor and a micro heater. Because there is a conduction type sensor part, it is easily destroyed by a slight contact. Therefore, it is necessary to prevent destruction of a thin film such as a cantilever due to handling for attachment of a heater / temperature sensor element or collision of particles such as dust mixed in an air flow. In the present invention, a cover (lid) that does not come into contact with a thin film such as a cantilever is bonded to the side of the substrate where the thin film such as a cantilever is formed to protect the thin film. In addition, the structure and arrangement of the electrode for taking out the lead wire to the outside is difficult because it is an ultra-small heater / temperature sensor element and a thin film floating in the air such as a cantilever exists. In the heater / temperature sensor element of the present invention, since only two terminals are required, at least two electrodes are sufficient. It is also a feature that at least one of the two electrodes is provided on the cover.

The airflow sensor of the present invention comprises a heater and temperature sensor element that can operate as a heater by self-heating the temperature sensor, and a pipe through which the gas flows, in the vicinity of the airflow inlet that corresponds to the terminal of the pipe, A heater and temperature sensor element is provided, and fluctuations in the gas flow can be detected by an electrical signal from the heater and temperature sensor element through the two wires.

The heater / temperature sensor element according to claim 2 of the present invention is a case where the temperature sensor is a pn junction diode, a Schottky junction diode, or a current detection type thermocouple.

When a temperature sensor having a large junction resistance, such as a pn junction diode or a Schottky junction diode, is used, it is convenient because the wiring resistance in the middle is easily ignored.

The airflow sensor according to claim 3 of the present invention is a case where at least a part of the thin film thermally separated from the substrate is covered with an electrically insulating and heat resistant plastic.

The thin film that is thermally separated from the substrate is often made of an extremely thin cantilever of about 10 micrometers (μm), for example. Therefore, it may be damaged by collision of fine particles mixed in the airflow. Further, it is often easy to break with a single crystal silicon thin film such as an SOI layer. If it is covered with a plastic thin film, it can protect the cantilever. Furthermore, if an electrically insulating plastic thin film is used, the wiring and electrode portions can be covered, and electrical insulation can be maintained even when there is contact with a conductive material. Of course, it can be used not only for the thin film portion thermally separated from the substrate, but also for electrical insulation of the wiring and electrode portions in the thin film portion immediately above the substrate. Further, since the heater / temperature sensor element is also used as a heater, heat resistance that can withstand temperatures of about 100 ° C. is required.

The airflow sensor according to claim 4 of the present invention is used as a vacuum pad in which the generation of airflow is based on vacuum suction.

Since the heater / temperature sensor element used here can be very small, it can also be installed in a minute space such as the inside of a vacuum pad (in this case, including a vacuum chuck and vacuum pin cent). In order to operate at high speed as an airflow sensor, it is necessary to attach a heater / temperature sensor element that is an airflow detection unit of the airflow sensor in the vicinity of the airflow inlet.

A vacuum pad is generally an object such as a semiconductor wafer, a chip, or a sphere by using a pressure difference from a vacuum pressure of 1 atm or less by vacuum suction with a vacuum pump. This is the case where this is achieved by using the air flow sensor that can be made ultra-small according to the present invention. In addition, in a vacuum pad, the negative pressure as dynamic pressure can also be formed by making compressed air 1 atmosphere or more with a compressor and flowing this. Thus, even if it is a negative pressure, this pressure may exceed 1 atmosphere. In such a state, vacuum suction is also performed by generating a low pressure compared to the surrounding high pressure, and is not necessarily a vacuum of 1 atm or less, but is used in the meaning of a pseudo vacuum.

Airflow sensor according to claim 5 of the present invention, at least in part on the electrically insulating material of the pipe, and Yes in flexible tube is provided by forming a conductive film on the inside and outside of the tube There is a case where the inner and outer conductive films can be used as wiring to the heater / temperature sensor element.

Connection to a vacuum pump or the like requires a pipe, and even if there is a flexible tube connected to the pipe, the heater / temperature sensor element is installed near the inlet of the air flow, and the pipe or tube It is better to install it in the area where air resistance is not affected.

The heater / temperature sensor element only needs two terminals for supplying electric power to the heater and taking out an electric signal as a temperature sensor simultaneously or by time division. In addition, a tube is used for a circuit for controlling the vacuum pad, a signal processing circuit, and the like, which makes the device more compact. Fortunately, the tube has two surfaces on the inside and the outside, and the present invention is a case where this surface is used as a wiring. A conductive film such as a metal film can be formed on the inner and outer surfaces of the tube, for example, by plating.

The airflow detection device according to claim 6 of the present invention is necessary for using the airflow sensor of the present invention , driving the airflow sensor, and measuring and controlling the change of the airflow from the electrical signal from the airflow sensor. And at least an amplifying circuit, an arithmetic circuit, and a control circuit.

A tube with a conductive film according to claim 7 of the present invention is the pipe used for the airflow sensor according to claim 5 , and is an electrically insulating material, and has conductive films on the inside and outside of the flexible tube, It is characterized in that it can be used as a wiring that conducts to at least one heater / temperature sensor element.

Since it is an electrically insulating material and flexible tube, it is a tube with a conductive film that uses conductive films on both the inside and outside for wiring such as a vacuum pad with a fine hole suction part used for vacuum tweezers etc. Is also useful.

In the airflow sensor of the present invention, the temperature sensor formed in a thin film thermally separated from the substrate is used as a heater by self-heating, so only two terminals are necessary for wiring, and it is attached to a very small space such as a vacuum pad. There is an advantage that it is possible to provide an airflow sensor having an ultra-small heater / temperature sensor element.

In the airflow sensor of the present invention, the temperature sensor is provided on, for example, a cantilever thin film that is thermally separated from the substrate. Therefore, the thin film has a structure that is easily broken. In the present invention, a cover is provided so that the thin film can be protected, and an electrode from which wiring such as a lead wire can be taken out is also formed. There is an advantage that it is advantageous.

In the airflow sensor of the present invention, since a semiconductor junction such as a pn junction diode or a Schottky junction diode can be used, the internal resistance can be made relatively large, so that the resistance of the wiring can be easily ignored.

In the airflow sensor of the present invention, the extremely small heater / temperature sensor element of the present invention is used, so that it can be attached to a minute space such as a vacuum pad and a high-speed response can be achieved.

The air current sensor for a vacuum pad according to the present invention uses the high-speed response air flow sensor according to the present invention, so that it is also a high-speed response, and there is an advantage that productivity is improved because the conveying speed of an object such as a chip increases.

Since the tube with a conductive film of the present invention can be used, it is unnecessary to separately provide complicated wiring such as a lead wire between the main body and there is an advantage that a vacuum pad as a compact airflow sensor can be provided. .

In the airflow detection device of the present invention, since the small airflow sensor is used with the high-speed response of the present invention, a small device with a high-speed response can be provided.

Hereinafter, the heater / temperature sensor element used in the airflow sensor of the present invention can be formed using an SOI substrate, which is a silicon (Si) substrate, using mature semiconductor integration technology and MEMS technology. A detailed description will be given based on an example with reference to the drawings in the case of manufacturing using this SOI substrate. Also, an airflow sensor using the heater / temperature sensor element of the present invention, a vacuum pad using this airflow sensor, and a tube with a conductive film used therefor will be described, and an airflow detection device using the airflow sensor of the present invention will be described This will be described with reference to a block diagram.

  FIG. 1 shows a schematic cross-sectional view of an embodiment of the heater / temperature sensor element of the present invention. This element includes a heat conduction type sensor chip 101 and a cover 300. This heat conduction type sensor chip 101 is manufactured by MEMS technology using an SOI substrate, and a pn junction diode 23 as a temperature sensor 20 is formed on the SOI layer 11 in the form of a cantilever 15 that is suspended in the air to thermally separate from the substrate 1. It is created near its tip. Further, the temperature sensor 20 comprising the pn junction diode 23 can be used as a heater because it can generate heat due to Joule heat when a large amount of current flows in the forward direction. Here, this is called a heater and temperature sensor. When the Joule-heated heater / temperature sensor is used as a diode thermistor, for example, when a forward voltage of 1.4 V is applied to the pn junction diode 23 formed in the cantilever 15, the temperature rises by about 50 ° C. from Joule heat. Operate as a heater. Moreover, when this state is exposed to an air current, heat is taken away by the air current and the temperature decreases. When the temperature decreases, the forward current of the diode decreases in a fixed state where the forward voltage is 1.4 V, and it can be operated as a temperature sensor, that is, a diode thermistor. This current change can be detected to correspond to the flow velocity or flow rate of the airflow, which is the principle of the airflow sensor of the present invention.

In the heat conduction type sensor chip 101, for example, the cantilever 15 made of a thin SOI layer 11 of about 10 μm is very easily broken, and therefore, the case where the surface is coated with a plastic 200 and is covered is shown. This plastic film is preferably electrically insulative so as to cover the electrodes and be electrically insulated, and heat resistant for Joule heating. In addition, for pattern formation, a material that can be formed by applying a photosensitive material such as a photoresist is good, for example, a photosensitive epoxy resin is good.

In addition, when the electrode 70 is formed on the back surface of the heat conduction type sensor chip 101, one terminal of the temperature sensor 20 formed of the pn junction diode 23 is connected to the electrode 70 on the back surface of the substrate 1. ing. For example, the SOI layer 11 is made of an n-type silicon semiconductor, and a pn junction diode 23 is formed by diffusing p-type impurities therein, and the SOI layer 11 of the n-type silicon semiconductor and the base substrate 12 of the substrate 1 are connected. When conducting through the ohmic contact 29, the n-type electrode of the pn junction diode 23 can be used as the electrode 70 on the back surface of the substrate 1 that is the heat conduction type sensor chip 101. This state is shown in the first embodiment. Further, the other terminal of the temperature sensor 20 is a conductive adhesive on the heat conduction type sensor chip 101 through the wiring 110 (not shown in FIG. 1, see FIG. 2) from the electrode 70 on the pn junction diode 23. 310 is conducted through the through hole 320 to the electrode 71 formed on the surface of the cover 300. These electrode 70 and electrode 71 are used as two terminals of the power source.

In FIG. 1, the cover 300 of the heater / temperature sensor element is bonded to the heat conduction type sensor chip 101 having the cantilever 15 and the like formed on the substrate 1 by using a conductive adhesive 310, and is covered through the through hole 320. The case where the electrode 71, such as a metal, is formed so that it may conduct | electrically_connect to the surface part of 300 is shown. The cover 300 is further provided with a hollow through-hole 320 so that airflow can be blown through the cavity 40 of the heat conduction type sensor chip 101. Since this structure does not energize the airflow, the sensitivity of the airflow sensor can be increased.

FIG. 2 shows an embodiment of a schematic diagram of the heat conduction type sensor chip 101 of the heater / temperature sensor element used in the airflow sensor of the present invention. FIG. 2 (a) is a plan view thereof, FIG. FIG. 2B is a schematic cross-sectional view taken along line X1-X1, and FIG. 2C is a schematic cross-sectional view taken along line X2-X2 in FIG. In the case where an n-type SOI substrate is used as the substrate 1, a cantilever 15 is formed by MEMS technology using the SOI layer 11, and a pn junction diode 23 as a temperature sensor 20 is formed at the tip thereof. The pn junction diode 23 forms a p-type diffusion region 22 by thermally diffusing p-type impurities in the n-type SOI layer 11 and leads the electrode 70 a through the ohmic contact 29 and the electrode 70 and the wiring 110. The other electrode 70 b is electrically connected to the n-type region of the pn junction diode 23 through the n-type SOI layer 11 and further through the ohmic contact 29 with the n-type diffusion region 21 in which impurities are diffused in the vicinity of the electrode 70 b. doing. Furthermore, the electrode 70 b is electrically connected to the electrode 70 formed on the back surface thereof through the base substrate 12 of the substrate 1. Therefore, the electrode 70 can be used as one terminal of the temperature sensor 20. In addition, since a thin film of plastic 200 is formed to protect the cantilever 15 from breakage and is an electrically insulating plastic 200, a cover 300 (not illustrated here) is covered by covering the electrode 70b. Reference) It is also used as an electrically insulating film so that itself or its surface may be a conductor.

FIG. 3 shows a schematic cross-sectional view of an embodiment in the vicinity of the suction pad in the vacuum pad of the present invention when the airflow sensor equipped with the heater / temperature sensor element of the present invention is applied to the vacuum pad. .

FIG. 3 shows a state in which the heater / temperature sensor element 100 of the present invention is attached with a conductive paste in the vicinity of the end of the pipe 600 that is in the vicinity of the airflow inlet of the metal pipe 600. . A conductive paste is attached to the cover 300 side of the heater / temperature sensor element, and the metal pipe 600 is electrically joined to one electrode of the heater / temperature sensor element. This metal pipe 600 is used as one terminal of the heater / temperature sensor element 100. At that time, the cavity 40 on the back surface of the heat conduction type sensor chip 101 directly touches the air flow of the pipe 600, and the temperature sensor 20 formed on the cantilever 15 of the heat conduction type sensor chip 101 is heated. Therefore, airflow can be detected. At this time, the through hole 320 formed in the cover 300 smoothes the airflow. A wiring 110 as a lead wire is taken out by the ohmic contact 29 from the other electrode formed on the back surface of the heat conduction type sensor chip 101 of the heater / temperature sensor element 100 and used as the other of the two terminals. The Here, a suction pad 700 made of rubber or the like is also drawn.

In FIG. 4, the cross-sectional schematic of one Example of the tube with an electrically conductive film of this invention is shown. This is a case where a conductive film 150 formed on the inside and outside of the tube 500 is formed on a flexible electrically insulating tube 500 by electroless plating or the like. This conductive film 150 is used as two wirings that conduct to the heater / temperature sensor element 100 of the present invention.

Since the tube 500 is vacuumed, for example, a thick vinyl tube may be used, and electroless plating copper plating may be used. A conductive adhesive may be used, or it may be attached by soldering with a wire from the heater / temperature sensor element 100. However, the inner and outer sides are simply fitted into the conductive film tube of the present invention with a dedicated adapter. Each of the conductive films 150 may be directly connected to two terminals of the heater / temperature sensor element 100.

FIG. 5 shows an embodiment of a block diagram of the airflow detection device of the present invention. Here, the airflow sensor main body (enclosed by a broken line) is built in which the airflow sensor is driven, the change in the airflow is measured from the electric signal from the airflow sensor, and the amplifier circuit, arithmetic circuit and control circuit necessary for control are built in. And a power supply section necessary for these operations and a display section for displaying the current operation state and the like. Each of these circuits and the like can be achieved with existing technology, and details thereof are omitted.

The heater / temperature sensor element of the present invention, an airflow sensor using the same, a vacuum pad using the airflow sensor, a tube with a conductive film used therein, and an airflow detection device using the airflow sensor are limited to the present embodiment. However, the present invention has the same gist, operation and effect, and various modifications can be naturally made.

The airflow sensor of the present invention achieves changes in gas flow rate and flow velocity by a heat-conducting sensor using a thermal sensor, not by a change in conventional atmospheric pressure, and can be manufactured in an ultra-small size and requires only two terminals. Therefore, when it is realized as an airflow sensor, the response speed is fast, and when applied to a vacuum pad, an extremely high-speed object can be captured by vacuum suction. Therefore, a high-speed transfer operation that is not possible in the past is possible, and the productivity is improved, which can greatly contribute to the industry. Moreover, a compact airflow sensor and a vacuum pad can be provided by providing a tube with a conductive film. Furthermore, an airflow detection device equipped with a compact airflow sensor is also compact, and an inexpensive device can be provided.

It is a cross-sectional schematic diagram of one Example of the heater and temperature sensor element used for the airflow sensor of this invention. Example 1 It is the schematic of one Example of the heat conduction type sensor chip 101 of the heater and temperature sensor element used for the airflow sensor of this invention. Example 1 It is the cross-sectional schematic of one Example of the suction pad vicinity in the vacuum pad using the airflow sensor of this invention. (Example 2) It is a cross-sectional schematic diagram of one Example of the tube with an electrically conductive film of this invention. (Example 3) It is a block diagram of one Example of the airflow detection apparatus of this invention. Example 4

DESCRIPTION OF SYMBOLS 1 Substrate 10 Thin film 11 SOI layer 12 Base substrate 15 Cantilever 20 Temperature sensor 21 N-type diffusion region 22 P-type diffusion region 23 pn junction diode 29 Ohmic contact 40 Cavity 42 Slit 45 Hollow part 50 Silicon oxide film 51 BOX layer 70, 70a 70b Electrode 71 Electrode 100 Heater / temperature sensor element 101 Heat conduction type sensor chip 110 Wiring 150 Conductive film 200 Plastic 300 Cover 310 Conductive adhesive 320 Through hole 500 Tube 600 Pipe 700 Adsorption pad

Claims (7)

In the airflow sensor mounted on the airflow detection device, a two-terminal heater that is formed on one surface side of the substrate and is used as a heater by self-heating a temperature sensor formed on a thin film thermally separated from the substrate it was and the temperature sensor element, and bonding the cover having a structure that does not contact with the thin film portion on the substrate, at least one of the two electrodes in the cover corresponding to the two terminals of the heater and the temperature sensor element An electrode is formed, a pipe through which a gas flows is provided, and the pipe has two wires connected to the heater / temperature sensor element, in the vicinity of the inlet inside the pipe. The heater / temperature sensor element is small enough to be installed therein, and fluctuations in the gas flow are detected by an electrical signal through the two wires from the heater / temperature sensor element. It thus was possible, the airflow sensor according to claim. The airflow sensor according to claim 1, wherein the temperature sensor is a pn junction diode, a Schottky junction diode, or a current detection type thermocouple. 3. The airflow sensor according to claim 1, wherein at least a part of the thin film thermally separated from the substrate is covered with an electrically insulating and heat resistant plastic. The airflow sensor according to any one of claims 1 to 3, wherein the airflow sensor is used as a vacuum pad whose generation of airflow is based on vacuum suction . At least a part of the pipe is provided with an electrically insulating material and a flexible tube, and a conductive film is formed on the inside and outside of the tube, and the inside and outside conductive films are heated. The airflow sensor according to any one of claims 1 to 4, wherein the airflow sensor can be used as wiring to the temperature sensor element . An amplifying circuit and a calculation required for controlling the airflow sensor according to any one of claims 1 to 5 , driving the airflow sensor, measuring a change in the airflow from an electric signal from the airflow sensor, and controlling the change. An airflow detection device comprising at least a circuit and a control circuit. 6. The pipe for use in the airflow sensor according to claim 5, wherein the heater and temperature sensor elements are made of an electrically insulating material and have at least one conductive film inside and outside the flexible tube. A tube with a conductive film, characterized in that it can be used as a wiring that is electrically connected to the conductive film.

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