JP2010281576A - Current sensor and electronic component incorporating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable current detection without electrically connecting a detection circuit to a circuit to be measured, and enable size reduction at low cost, in a current sensor and an electronic component incorporating the current sensor. <P>SOLUTION: The current sensor includes: a substrate 11; a current heat conversion section 14, where a pair of electrode films 12 connected to the circuit, a first conducive material film 13A connected to one of the pair of electrode films 12, and a second conductive material film 13B that is joined to the first conductive material film 13A, is connected to the other of the pair of electrode films 12, and has a value of resistance larger than that of the first conductive material film 13A are subjected to pattern formation on the substrate 11; an insulation film 15 on the first and second conductive material films 13A, 13B; and a thin-film thermocouple section 17 formed from an upper portion of the first conductive material film 13A to that of the second conductive material film 13B, and is composed of at least a first thermoelectric film 16A and a second thermoelectric film 16B in a pair electrically connected in series while being joined at edges. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a current sensor capable of detecting a current flowing in a circuit and an electronic component with a built-in current sensor.

  As a technique for measuring the current flowing through various circuits, conventionally, a technique using a shunt resistor, a current transformer (CT), a Hall element, or the like has been used. In current detection using the shunt resistor, a shunt resistor is connected to the circuit, the current is converted into a voltage, and the voltage is measured by a detection circuit connected to the shunt resistor to detect the current. In current detection using this shunt resistor, both direct current and alternating current can be measured.

In addition, in current detection using a current transformer, a circuit to be measured in which an alternating current flows is connected to a primary coil wound around an annular core, and a voltage generated in a secondary coil wound around the annular core is detected. The detection circuit detects the current.
Furthermore, in current detection using a Hall element, for example, as shown in Patent Document 1, a Hall element, which is a magnetic sensor using the Hall effect, is installed in the vicinity of the circuit, and is generated according to the circuit current by the Hall element. The current is detected by capturing the magnetic field. In this Hall element, a current can be detected without contact with a circuit to be measured.

JP 2008-20402 A

The following problems remain in the conventional technology.
That is, in current detection using a shunt resistor, the detection circuit must be electrically connected to the circuit to be measured via the shunt resistor. However, in order to ensure the safety and reliability of the detection circuit for current detection of high-voltage power supplies and for impulse noise due to large currents, etc. There is a need for a method of detecting current without being electrically connected to the circuit. For this reason, as shown in FIG. 9, when a direct connection is made to the circuit EC from the high voltage power supply 1, a current transformer 4 is inserted into the detection circuit 3 for detecting the voltage of the shunt resistor 2 and electrically separated. Current detection. However, the insertion of the current transformer 4 increases the shape and the number of components, leading to an increase in cost and an increase in the sensor shape. In addition, current detection using a Hall element has an inconvenience of being expensive because an expensive Hall element (magnetic sensor) is used.

  The present invention has been made in view of the above-described problems, and is capable of detecting a current without electrically connecting a detection circuit to a circuit to be measured, and a current sensor and a current that can be reduced in size at low cost. An object is to provide an electronic component with a built-in sensor.

  The present invention employs the following configuration in order to solve the above problems. That is, the current sensor of the present invention is bonded to the substrate, the pair of electrode films connected to the circuit, the first conductor film connected to one of the pair of electrode films, and the first conductor film. And a second heat conductive film connected to the other of the pair of electrode films and having a resistance value higher than that of the first conductive film, and formed into a pattern on the substrate; An insulating film formed on the first conductive film and the second conductive film, and above the first conductive film on the insulating film from above the first conductive film. A p-type thermoelectric material and an n-type thermoelectric material which are different from each other, and at least a pair of first thermoelectric films and second thermoelectric films which are joined in ends and electrically connected in series. And a thin film thermocouple portion configured.

In this current sensor, the thin film thermocouple portion is formed of a p-type thermoelectric material and an n-type thermoelectric material that are different from each other from above the first conductor film to above the second conductor film, and at the end. Since the first thermoelectric film and the second thermoelectric film are joined to each other, the temperature difference between the first conductor film and the second conductor film according to the current flowing through the current-to-heat converter. Is generated, and an electromotive force is generated in the thin film thermocouple portion, whereby a current can be detected.
That is, when a current flows through the current-to-heat converter connected to the circuit to be measured, the second conductor film having a higher resistance value than the first conductor film has a higher Joule heat than the first conductor film. And generates a temperature difference between the first conductor film and the second conductor film in accordance with the current. Due to this temperature difference, an electromotive force is generated in the thin film thermocouple portion installed from the first conductor film to the second conductor film. At this time, since the temperature difference due to Joule heat generated in the current-to-heat conversion unit is proportional to the amount of current passing therethrough, the electromotive force is also proportional to the amount of current, so that the current can be detected by this electromotive force. In particular, since both the current-to-heat converter and the thin film thermocouple are film-like, the cross-sectional area between the portions where the temperature difference occurs can be reduced. Becomes larger and the detection sensitivity is improved.
In this way, it is possible to detect the current of the circuit without electrically connecting the thin film thermocouple unit connected to the detection circuit to the current-to-heat conversion unit connected to the circuit to be measured. Further, since the current can be detected by measuring the electromotive force of the thin film thermocouple portion, a simple detection circuit is sufficient, and the device can be manufactured at low cost. Furthermore, since the thin film thermocouple unit is simple and inexpensive, the member cost is low and the size can be reduced.
In addition, since the current-to-heat conversion part and the thin film thermocouple part are both patterned with a thin film on the substrate, they can be manufactured at a low cost and can be thinned.

The current sensor according to the present invention is characterized in that a plurality of pairs of the first thermoelectric film and the second thermoelectric film are alternately connected to each other and folded to be arranged in a comb-like shape as a whole. To do.
That is, in this current sensor, a plurality of pairs of the first thermoelectric film and the second thermoelectric film are alternately connected to each other and folded, and arranged in a comb-like shape as a whole. Many thermocouple parts can be connected in series, and a high electromotive force can be obtained.

An electronic component with a built-in current sensor according to the present invention includes a substrate, a circuit formed on the substrate, and the current sensor according to the present invention formed on the substrate and having the pair of electrode films connected to the circuit. It is characterized by.
That is, this electronic component with a built-in current sensor includes the current sensor of the present invention formed on a substrate and connected to a circuit with a pair of electrode films, so that the current sensor integrally formed with the circuit on the substrate A small electronic component with a built-in current sensor can be obtained.

In the electronic component with a built-in current sensor according to the present invention, the substrate is a semiconductor substrate, and the circuit includes a semiconductor element.
That is, in this electronic component with a built-in current sensor, since the substrate is a semiconductor substrate and the circuit includes a semiconductor element, it can be integrated on a single chip together with the current sensor by a semiconductor manufacturing technique such as a photolithography technique. Further downsizing and cost reduction can be achieved.

The present invention has the following effects.
That is, according to the current sensor and the electronic component with built-in current sensor according to the present invention, the thin film thermocouple portion is formed from above the first conductor film to above the second conductor film and at the end. Since the first thermoelectric film and the second thermoelectric film are joined to each other, the temperature difference between the first conductor film and the second conductor film according to the current flowing through the current-to-heat converter. Is generated, and an electromotive force is generated in the thin film thermocouple portion, whereby a current can be detected. Therefore, it is possible to detect the current of the circuit without making an electrical connection to the current-to-heat converter, and the thin-film thermocouple unit is inexpensive and the detection circuit is simple, so the cost and size can be reduced. is there.

1 is a plan view showing a current sensor in an embodiment of a current sensor and an electronic component with built-in current sensor according to the present invention. In this embodiment, it is an enlarged plan view of the principal part which shows joining of the 1st thermoelectric film and the 2nd thermoelectric film. In this embodiment, it is an equivalent circuit schematic of the current sensor connected to the circuit to be measured. In the current sensor according to this embodiment, the first conductor film, the second conductor film, and the electrode film are formed on the substrate, and the first conductor film and the second conductor film are insulated. It is a top view which shows the state in which the film | membrane was formed. In this embodiment, it is sectional drawing of the principal part (AA line of FIG. 2) which shows the manufacturing method of a thin film thermocouple part in order of a process. In this embodiment, it is sectional drawing which shows the electronic component with a built-in current sensor made into 1 chip. In this embodiment, it is an equivalent circuit diagram which shows the electronic component with a built-in current sensor. In the prior art example which concerns on this invention, it is an equivalent circuit schematic of the current sensor connected to IGBT. In the conventional example which concerns on this invention, it is an equivalent circuit schematic of the current detection circuit connected to the circuit of a measuring object.

  Hereinafter, an embodiment of a current sensor and an electronic component with a built-in current sensor according to the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed so that each member can be recognized or easily recognized.

  As shown in FIGS. 1 to 3, the current sensor 10 of the present embodiment includes a substrate 11, a pair of electrode films 12 connected to a circuit EC to be measured, and a first electrode film 12 connected to one of the pair of electrode films 12. The first conductor film 13A and the second conductor film bonded to the first conductor film 13A and connected to the other of the pair of electrode films 12 and having a higher resistance value than the first conductor film 13A 13B is formed by patterning on the substrate 11, the current-to-heat conversion unit 14, the insulating film 15 formed on the first conductor film 13A and the second conductor film 13B, and the insulating film 15 is formed in a belt-like pattern with different p-type thermoelectric material and n-type thermoelectric material from above the first conductor film 13A to above the second conductor film 13B and joined at the end. A plurality of pairs of first thermoelectric films 16A electrically connected in series A thin film thermocouple portion 17 composed of a second thermoelectric film 16B, and a pair of electrode end portions 18 connected to the ends of the first thermoelectric film 16A and the second thermoelectric film 16B connected in series. I have.

The substrate 11 is formed of a semiconductor substrate such as a silicon substrate, for example.
The first conductor film 13A is formed of, for example, a copper film, and the second conductor film 13B is formed of an alloy film of copper and nickel. That is, the first conductor film 13A formed of copper has a resistance value of approximately 0Ω, whereas the second conductor film 13B to which nickel is added as an impurity has a resistance value of about 0Ω. It is set to 0.1 mΩ.

The insulating film 15 is, for example, a SiO ₂ film.
As shown in FIG. 2, the first thermoelectric film 16A and the second thermoelectric film 16B joined to each other at the end are bent in an L shape so that the end of one thermoelectric film is the other thermoelectric film. A joining portion 16a is formed so as to overlap the end portion.

  That is, the first thermoelectric film 16 </ b> A and the second thermoelectric film 16 </ b> B are connected to each other at the joint portion 16 a at the end portion to constitute one thermocouple portion. The first thermoelectric film 16A and the second thermoelectric film 16B are arranged in a comb-like shape as a whole by being alternately connected and folded, and a plurality of thermocouple parts are repeatedly connected in series. Has been. The sensitivity is increased by increasing the number of repetitions of the pattern of the thermocouple portion by the first thermoelectric film 16A and the second thermoelectric film 16B (the number of connections between the first thermoelectric film 16A and the second thermoelectric film 16B). Can be improved.

In the first thermoelectric film 16A and the second thermoelectric film 16B, for example, both a p-type thermoelectric material and an n-type thermoelectric material are formed of a FeSi ₂ -based thermoelectric material. For example, a known Bi—Te thermoelectric material, Mg—Si thermoelectric material, Mn—Si thermoelectric material, and oxide thermoelectric material may be used in addition to the FeSi ₂ thermoelectric material.

  Next, a method for manufacturing the current sensor 10 of the present embodiment will be described with reference to FIGS.

  First, for example, a silicon substrate is used as the substrate 11, and as shown in FIG. 4A, a copper film, for example, is formed on the surface of the substrate 11 as the first conductor film 13A and the second conductor film 13B. And an alloy film of copper and nickel is formed in a predetermined pattern in a bonded state at the center by sputtering or the like. Furthermore, the electrode film 12 is patterned with a metal film such as gold, copper, or aluminum at the end of the first conductor film 13A and the end of the second conductor film 13B.

Then, as shown in shown in FIG. 4 (b) and 5 (a), the surface of the first conductive film 13A and the second conductive film 13B, for example, an insulating film 15 of SiO ₂ film a predetermined pattern The film is formed.
Next, as shown in FIG. 5B, for example, a p-type FeSi ₂ film is deposited as a first thermoelectric film 16A to a predetermined thickness on the entire surface of the substrate 11 including the insulating film 15 by sputtering. . Further, as shown in FIG. 5C, a first photoresist film 21 having a predetermined pattern is formed by depositing a first photoresist film 21 on the first thermoelectric film 16A, exposing the first photoresist film 21, and so on. .

Subsequently, as shown in (d) of FIG. 5, the first thermoelectric selectively etched to underlying other portion of the first photoresist film 21 with an etching solution of HF + HNO ₃ based or HF ₊ H 2 SO ₄ system or the like The film 16A is removed. As shown in FIG. 5E, the first photoresist film 21 is further removed to form a pattern of the first thermoelectric film 16A on the substrate 11.

Next, as shown in FIG. 5 (f), the first thermoelectric film 16A is covered with a second photoresist film 22, exposed and etched, and a predetermined pattern is formed on a part of the first thermoelectric film 16A. The second photoresist film 22 is left. Furthermore, as shown in (g) in FIG. 5, the substrate 11, depositing a ZrO ₂ film as the insulating layer 24 to cover the entire first thermoelectric film 16A and the second photo-resist film 22. Then, as shown in FIG. 5H, a part of the pattern of the first thermoelectric film 16A is exposed by peeling off the second photoresist film 22 together with a part of the insulating layer 24 by a lift-off method. Exposed as 16b.

Next, as shown in FIG. 5I, the second thermoelectric film 16B is deposited by sputtering or the like so as to cover the exposed portion 16b of the first thermoelectric film 16A and the entire insulating layer 24. Further, as shown in FIG. 5J, a third photoresist film 23 having a predetermined pattern is deposited on the second thermoelectric film 16B. Then, as shown in FIG. 5K, the second thermoelectric film 16B other than the base of the third photoresist film 23 is selectively etched with an etching solution such as HF + HNO ₃ . Further, as shown in FIG. 5L, the third photoresist film 23 is removed. As a result, a part of the first thermoelectric film 16A (exposed part 16b) and a part of the second thermoelectric film 16B are joined to form a joined part 16a.

Next, annealing is performed at 400 to 900 ° C. in order to crystallize the first thermoelectric film 16A and the second thermoelectric film 16B. This annealing increases the thermoelectromotive force.
Then, the current sensor 10 is fabricated by patterning the electrode end 18 with a metal film such as copper or aluminum at the ends of the connected first thermoelectric film 16A and second thermoelectric film 16B.

  When the current of the circuit EC to be measured is detected by the current sensor 10, the current-heat converter 14 is connected to the circuit EC connected to the high voltage power supply 1 as shown in FIG. That is, the current-to-heat converter 14 is connected to the circuit EC to be measured in the same manner as a conventional shunt resistor. Further, the detection circuit 43 is connected to the pair of electrode films 12 of the thin film thermocouple unit 17 attached to the current heat conversion unit 14. In addition, the code | symbol 19 shown in FIG. 3 is a load part in the circuit EC.

  When a current flows through the current-to-heat converter 14 connected to the circuit EC to be measured, the second conductor film 13B having a higher resistance value than the first conductor film 13A is higher than the first conductor film 13A. Heat is generated by Joule heat, and a temperature difference is generated between the first conductor film 13A and the second conductor film 13B according to the current. Due to this temperature difference, an electromotive force is generated in the thin film thermocouple portion 17 installed from the first conductor film 13A to the second conductor film 13B. At this time, since the temperature difference due to Joule heat generated in the current-to-heat converter 14 is proportional to the amount of current passing therethrough, the electromotive force is also proportional to the amount of current. Therefore, the current can be detected by this electromotive force. In particular, the current-to-heat conversion unit 14 and the thin film thermocouple unit 17 are both film-like, so that the cross-sectional area between the portions where the temperature difference occurs can be reduced. The temperature difference increases and detection sensitivity improves.

  As described above, in the current sensor 10 according to the present embodiment, the thin film thermocouple unit 17 has different p-type thermoelectric material and n-type thermoelectric material from above the first conductor film 13A to above the second conductor film 13B. And the first thermoelectric film 16A and the second thermoelectric film 16B joined at the end portions, so that the first conductor film according to the current flowing through the current-to-heat conversion section 14 A current can be detected by causing a temperature difference between 13A and the second conductive film 13B and generating an electromotive force in the thin-film thermocouple unit 17.

  Accordingly, it is possible to detect the current of the circuit EC without electrically connecting the thin film thermocouple unit 17 connected to the detection circuit 43 to the current-heat conversion unit 14 connected to the circuit EC to be measured. Further, since the current can be detected by measuring the electromotive force of the thin film thermocouple unit 17, a simple detection circuit 43 is sufficient, and the device can be manufactured at low cost. Furthermore, since the thin film thermocouple unit 17 has a simple configuration and is inexpensive, the member cost is low and the size can be reduced.

In addition, since the current-to-heat conversion unit 14 and the thin film thermocouple unit 17 are both patterned with a thin film on the substrate 11, they can be manufactured at a low cost and can be thinned.
Further, since the plurality of pairs of the first thermoelectric film 16A and the second thermoelectric film 16B are alternately connected to each other and folded and arranged in a comb-like shape as a whole, the thermocouple portion is formed by the folded structure even in a small space. Can be connected in series, and a high electromotive force can be obtained.

  Next, a current sensor built-in electronic component incorporating the current sensor of the present embodiment will be described with reference to FIGS.

  As shown in FIGS. 6 and 7, the electronic component 30 with a built-in current sensor according to the present embodiment has an IGBT (Insulated Gate Bipolar Transistor) 31 used in a switching driver circuit and a current of the IGBT 31. This is an electronic component in which the current sensor 10 to be detected is integrated on one chip.

  That is, as shown in FIG. 6, an IGBT 31 having a gate G, an emitter E, and a collector C is formed on a silicon substrate 11 by a semiconductor manufacturing process, and the above current is present on the surface of the same substrate 11 in the vicinity of the IGBT 31. A sensor 10 is formed. Also, one electrode film 12 and the collector C of the IGBT 31 are connected via a fine metal wire 32 by wire bonding. In addition, the code | symbol p shown in FIG. 6 has shown the p-type semiconductor layer, and the code | symbol n has shown the n-type semiconductor layer.

Conventionally, as shown in FIG. 8, a current sensor component 33 such as a shunt resistor or a Hall element is separately connected to the IGBT 31 mounted on the circuit board and mounted on the circuit board. Further, the output of the current sensor component 33 is connected to the load circuit side.
On the other hand, in the electronic component 30 with a built-in current sensor of the present embodiment, as shown in FIG. 7, the IGBT 31 and the current sensor 10 are integrated into one chip and are integrated and mounted on a circuit board. The output (electrode end 18) of the sensor 10 is insulated without being connected to the load circuit side. In FIG. 7 and FIG. 8, reference numeral 34 is a load resistance, and reference numeral 35 is a power supply voltage.

As described above, the current sensor built-in electronic component 30 according to the present embodiment includes the current sensor 10 formed on the substrate 11 and connected to the IGBT 31 of the driver circuit to be measured. A small current sensor built-in electronic component can be obtained by the current sensor 10 integrally formed with the IGBT 31.
In particular, since the substrate 11 is a semiconductor substrate such as a silicon substrate, and the circuit to be measured includes the IGBT 31 of a semiconductor element such as an IGBT 31, it is integrated on a single chip together with the current sensor 10 by a semiconductor manufacturing technique such as a photolithography technique. Therefore, further downsizing and cost reduction can be achieved.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, although the first conductive film and the second conductive film are formed in a single layer in the above embodiment, a plurality of the first conductive film and the second conductive film may be stacked with an insulating layer interposed therebetween. I do not care. That is, the steps shown in FIGS. 5F to 5L in the lithography process are repeated for each layer, and the bonding portion is formed while alternately patterning the first thermoelectric film and the second conductor film. By excluding the insulating layer, a plurality of layers having a plurality of thermocouple portions electrically connected in series are stacked.

In this case, since a plurality of first conductive films and a plurality of second conductive films are laminated via an insulating layer, a large number of thermocouple portions can be connected in series with a multilayer structure even in a small space, which is even higher. An electromotive force can be obtained. In particular, a clearer temperature difference can be obtained by forming the insulating layer with a material having low thermal conductivity such as a ZrO ₂ film.
In the above embodiment, the IGBT and the current sensor are integrated on a single chip. However, a circuit such as an IC circuit including other semiconductor elements and the current sensor may be integrally formed on the same substrate.

  DESCRIPTION OF SYMBOLS 10 ... Current sensor, 11 ... Board | substrate, 12 ... Electrode film | membrane, 13A ... 1st conductor film, 13B ... 2nd conductor film | membrane, 14 ... Current heat conversion part, 15 ... Insulating film, 16A ... 1st thermoelectric Membrane, 16B ... second thermoelectric membrane, 17 ... thin film thermocouple, 30 ... electronic component with built-in current sensor, 31 ... IGBT (semiconductor element), EC ... circuit to be measured

Claims (4)

A substrate,
A pair of electrode films connected to a circuit, a first conductor film connected to one of the pair of electrode films, and joined to the first conductor film and connected to the other of the pair of electrode films And a current-to-heat conversion part configured by patterning the second conductor film having a higher resistance value than the first conductor film on the substrate;
An insulating film formed on the first conductor film and the second conductor film;
A p-type thermoelectric material and an n-type thermoelectric material that are different from each other are formed on the insulating film from above the first conductor film to above the second conductor film, and are joined at the ends. A current sensor comprising: a thin film thermocouple portion including at least a pair of first thermoelectric film and second thermoelectric film electrically connected in series. The current sensor according to claim 1.
A plurality of pairs of the first thermoelectric film and the second thermoelectric film are alternately connected to each other and folded, and arranged in a comb-like shape as a whole. A substrate,
A circuit formed on the substrate;
An electronic component with a built-in current sensor, comprising: the current sensor according to claim 1, wherein the current sensor is formed on the substrate and the pair of electrode films are connected to the circuit. In the electronic component with a built-in current sensor according to claim 3,
The substrate is a semiconductor substrate;
An electronic component with a built-in current sensor, wherein the circuit includes a semiconductor element.

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