Heat flux sensor, semiconductor device having the heat flux sensor, and method for manufacturing the heat flux sensor

Abstract

To provide a heat flux sensor that can be manufactured easily and at low cost, a semiconductor device having the heat flux sensor, and a manufacturing method for the heat flux sensor.SOLUTION: The heat flux sensor according to the present invention comprises a metallic magnetic film on a substrate. And the above metallic magnetic film has a part where the composition differs in its in-plane direction and is magnetized in the direction where the composition differs above, a heat flux is measured from a relation between the voltage (VL) between two points of the above metallic magnetic film with different compositions and the voltage (VT) between two points orthogonal to the above direction of magnetization and having the same composition, thereby the heat flux can be measured with a single metallic magnetic film, thus reducing the cost.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat flux sensor, a semiconductor device having the heat flux sensor, and a method for manufacturing a heat flux sensor, and more particularly to a film-type heat flux sensor that utilizes the magneto-thermoelectric effect, a semiconductor device having the heat flux sensor, and a method for manufacturing a heat flux sensor. [Background technology]

[0002] Conventional heat flux sensors that utilize the Seebeck effect are known. The Seebeck effect is a one-dimensional phenomenon in which the temperature gradient and electric field appear in the same axial direction, and heat flux sensors have a complex structure with a three-dimensional pn junction, which limits the flexibility of the shape to match the shape of the heat source and makes it difficult to reduce the cost.

[0003] Patent Document 1 discloses a thin heat flux sensor that uses the spin Seebeck effect, in which a first electromotive force that exhibits the inverse spin Hall effect and a second electromotive force that has a small temperature coefficient of internal resistance are formed on the surface of a magnetic body that has internal magnetization, and in which heat flow, magnetization, and an electric field are generated three-dimensionally. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-80394 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the heat flux sensor described in Patent Document 1 is a two-layer film in which an electromotive body is laminated on the surface of a magnetic body. In addition, the efficiency of generating thermoelectric power by the electromotive body is temperature dependent. Therefore, it is necessary to form two electromotive bodies in which the direction of current due to thermoelectric power is opposite and connect them in series for calibration, which makes it difficult to reduce costs.

[0006] The present invention has been made in consideration of the problems associated with the prior art, and an object of the present invention is to provide a heat flux sensor that is easy to fabricate at low cost, a semiconductor device having the heat flux sensor, and a method for manufacturing the heat flux sensor. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above-mentioned objective, the inventors discovered that the above-mentioned objective could be achieved by varying the composition of the metal magnetic film in the in-plane direction and measuring the voltage generated by the heat flux from two directions, thereby completing the present invention.

[0008] That is, the heat flux sensor of the present invention comprises a metal magnetic film on a substrate. The metal magnetic film has a portion where the composition is different in the in-plane direction, and the composition is magnetized in a direction where the composition is different, the composition of the metal magnetic film changes gradually or stepwise from one end to the other end, The voltage (V L ) and the voltage (V T ) and the heat flux is measured based on the relationship.

[0009] The present invention also provides a semiconductor device having the above heat flux sensor, characterized in that the above metal magnetic film is bonded to a semiconductor substrate.

[0010] Furthermore, a method for manufacturing a heat flux sensor of the present invention is a method for manufacturing the above-mentioned heat flux sensor, and includes the steps of forming a metal magnetic film on a substrate and magnetizing the formed metal magnetic film. The film forming process is characterized by using two or more types of targets with at least different compositions, placing a shutter that partially blocks each target between the substrate and each target, and simultaneously sputtering the two or more targets with different compositions. [Effects of the Invention]

[0011] According to the present invention, the composition of the metal magnetic film is varied in the in-plane direction, and the voltage generated by the heat flux is measured from two directions, thereby making it possible to provide a heat flux sensor that can be reduced in cost, a semiconductor device that has the heat flux sensor, and a method for manufacturing the heat flux sensor. [Brief explanation of the drawings]

[0012] [Figure 1] 1A and 1B are a plan view and a cross-sectional view showing an example of a heat flux sensor of the present invention. [Figure 2] FIG. 1 is a diagram illustrating the electromotive force (VT) in the direction of the same composition and the electromotive force (VL) in the direction of different compositions. [Figure 3] FIG. 1 is a cross-sectional view showing an example of a metal magnetic film having a laminated structure. [Figure 4] 1A and 1B are diagrams illustrating a state in which a metal magnetic film is formed by sputtering. [Figure 5] 1 is a cross-sectional view showing an example of a layer structure of a semiconductor device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Heat flux sensor> The heat flux sensor of the present invention will now be described in detail. As shown in FIG. 1, the heat flux sensor of the present invention comprises a metal magnetic film on a substrate, and the metal magnetic film has portions with different compositions in the in-plane direction and is magnetized in the direction in which the composition changes. Then, the voltage (V L ) and the voltage (V T ) and the heat flux is measured from the relationship between these voltages.

[0014] In the above-mentioned metal magnetic film, the direction of magnetization and the direction of composition are perpendicular to each other, and the direction of magnetization and the direction of composition change are in the same direction. In the direction of composition that is perpendicular to the direction of magnetization of the metal magnetic film, an electromotive force (V T ) occurs.

[0015] As mentioned above, the electromotive force (V T As shown in Figure 2, there is a difference between the electromotive force generated at one end of the metal magnetic film in the direction of magnetization and the electromotive force generated at the other end, which has a different composition from the one end, due to the difference in composition, and therefore a bias in the direction of the different composition occurs.

[0016] The anomalous Nernst effect does not occur in the direction of composition change that is parallel to the direction of magnetization where this charge imbalance occurs, and since this direction is also perpendicular to the thickness direction of the metal magnetic film, the Seebeck effect for the heat flux flowing in the thickness direction of the metal magnetic film does not occur either.

[0017] In this way, the electromotive force (V L ) depends only on the difference in composition and is not affected by the temperature dependence of the efficiency (thermoelectric coefficient) of the metal magnetic film itself when generating voltage from heat flux.

[0018] Therefore, the heat flux sensor of the present invention measures the voltage (V L ) and the voltage (V T ) the heat flux flowing in the film thickness direction of the metal magnetic film can be measured.

[0019] Specifically, when heat flows in the direction of the film thickness of a metal magnetic film, an electromotive force (V T ) and the electromotive force (V L ) are generated, and these are boosted by a voltage amplifier to 0 to 5 V, which can be digitally processed by a microcomputer.

[0020] Then, the heat flux and V T and V L and the actual measured V T and V L The heat flux is calculated from the heat flux and the obtained heat flux is output to the outside.

[0021] As described above, the heat flux sensor of the present invention only needs to extract electromotive forces in the direction where the composition is different and the direction where the composition is the same, so it is sufficient to provide pads for extracting electromotive forces in four locations.Furthermore, since there is no need to add a metal magnetic film to calibrate the effects of temperature dependence, it is sufficient to form a single metal magnetic film, making it easy to manufacture and possible to reduce costs.

[0022] The way in which the composition of the metal magnetic film changes can be adjusted depending on the intended use of the heat flux sensor, and may change gradually from one end to the other, or may change in stages.

[0023] When the composition of the metal magnetic film changes gradually, even if there is temperature variation within the surface of the metal magnetic material, it is possible to measure the heat flux that averages out this variation, and when the composition changes in stages, it is possible to locally increase the sensitivity due to heat flux within the surface of the metal magnetic film.

[0024] The two points where the composition of the metal magnetic body differs preferably differ by 30 at % or more in the content of the element whose content varies most between the two points, although this differs depending on the composition of the metal magnetic body.

[0025] When the content of the element whose content changes most between two points with different compositions in the above-mentioned metal magnetic body changes by 30 at% or more, when a temperature difference of 0.1 K (Kelvin) occurs between the top and bottom surfaces of the metal magnetic body, the voltage difference becomes 5% or more, and heat flux can be measured accurately with high sensitivity.

[0026] The material for forming the metallic magnetic film can be a ferromagnetic material or a diamagnetic material.

[0027] Examples of the ferromagnetic material include a combination of metal elements such as iron (Fe), cobalt (Co), and nickel (Ni), alloys containing these metals such as FeCo, FeNi, CoNi, FePt, and FePd, and alloys such as Co2MnGa, MnGa, and MnGe. Examples of the diamagnetic material include a combination of Mn3Sn and Mn3Ge.

[0028] If the metal magnetic film is made of a material with high thermal conductivity, such as a combination of simple metals, it is possible to prevent a decrease in the heat dissipation performance of the heat flux sensor.

[0029] Furthermore, when the metallic magnetic film is an antiferromagnetic film, it does not have spontaneous magnetization, and therefore it is possible to suppress adverse effects on other devices that utilize magnetism, for example.

[0030] The above-mentioned metal magnetic film can have a laminated structure in which a ferromagnetic film or a diamagnetic film is laminated with a paramagnetic film, as shown in Figure 3. When the metal magnetic film has a laminated structure including a paramagnetic film, an electromotive force due to the spin-Seebeck effect can also be obtained, and a large electromotive force can be obtained.

[0031] Furthermore, when the metal magnetic film has a laminated structure of an insulating ferromagnetic film and a paramagnetic film, the insulating ferromagnetic film has a low thermal conductivity, so a temperature gradient is easily generated between one side of the metal magnetic film and the other side, and a high electromotive force can be obtained, so that the voltage can be increased using an inexpensive heating circuit, thereby reducing costs. An example of the insulating ferromagnetic material is yttrium iron garnet.

[0032] The laminated structure can be not only a two-layer structure of a ferromagnetic or diamagnetic film and a paramagnetic film, but also a multi-layer structure in which multiple layers are laminated, and the magnitude of the electromotive force can be adjusted by the number of layers.

[0033] Examples of paramagnetic materials that can be used include simple substances such as palladium (Pd), platinum (Pt), tungsten (W), and tantalum (Ta), as well as alloys such as PdPt and WPt, which are combinations of these elements.

[0034] The substrate is not particularly limited, but a substrate made of a material on which a metal magnetic film can be formed by sputtering, such as a metal substrate, can be preferably used.

[0035] <Method of manufacturing heat flux sensor> Next, a method for manufacturing the heat flux sensor will be described. The method for manufacturing a heat flux sensor of the present invention includes the steps of forming a metal magnetic film on a substrate and magnetizing the formed metal magnetic film.

[0036] The process for forming the metal magnetic film can be carried out by any method that can form a metal magnetic film having portions with different compositions in the in-plane direction, such as sputtering, vapor deposition, plating, ink jetting, spray coating, etc. Among these, sputtering is particularly useful for producing a metal magnetic film with a gradually changing composition, and can reduce costs.

[0037] Specifically, as shown in Figure 4, two or more targets with different compositions are arranged parallel to the substrate, and a partially open shutter is placed between each target and the substrate.

[0038] One of the shutters blocks the sputtered material of one target so that it is difficult for the one target to reach the side where a film is formed in large quantities on the other target, and the other shutter blocks the sputtered material of the other target so that it is difficult for the other target to reach the side where a film is formed in large quantities on the one target.

[0039] In this way, by placing the partially open shutter and simultaneously sputtering two or more types of targets, the target materials can reach different locations on the substrate, making it possible to produce a metal magnetic film whose composition gradually changes from one end to the other.

[0040] The magnetization step is a step of magnetizing the formed metal magnetic film in the direction in which its composition changes, and the formed metal magnetic film can be made magnetic by passing the formed metal magnetic film together with the substrate through a magnetic field. An electromagnet or the like can be used as a means for magnetizing the metal magnetic film.

[0041] Then, a pad for extracting electromotive force is provided on the magnetized metal magnetic film and connected to a voltmeter to create a heat flux sensor.

[0042] <Semiconductor device> The heat flux sensor of the present invention can be suitably used for measuring the heat convergence of a semiconductor device. The semiconductor device of the present invention has a semiconductor chip on a semiconductor substrate, and a metal magnetic film of a heat flux sensor is bonded to the surface of the semiconductor substrate opposite to the semiconductor chip.

[0043] By bonding the metal magnetic film to the semiconductor substrate, the response of the electromotive force generated in the metal magnetic film is improved, enabling rapid temperature control by feeding back the measured heat flux.

[0044] In the semiconductor device, it is preferable that the metal magnetic film of the heat flux sensor is larger than the semiconductor substrate, and the area of ​​the region of the metal magnetic film having the same composition is smaller than the area of ​​the semiconductor substrate. When the metallic magnetic film and the semiconductor substrate have such a magnitude relationship, it is possible to measure the heat flux flowing locally.

[0045] Furthermore, if the substrate of the heat flux sensor of the semiconductor device is a heat dissipator such as a heat spreader or a heat sink, heat can be dissipated through the heat flux sensor.

[0046] Such a semiconductor device of the present invention can be fabricated by joining the metal magnetic film of the heat flux sensor to the semiconductor substrate with solder or the like. [Explanation of symbols]

[0047] 1. Heat flux sensor 2 boards 3 Metal magnetic film 31 Ferromagnetic film 32 Paramagnetic film 4 pads 5a Target 5b Target 6a Shutter 6b Shutter 7a Magnet 7b Magnet 8 electrodes 9. Vacuum Chamber 21 Heat spreader (substrate) 50 Semiconductor substrate 60 metal layer 70 solder

Claims

1. A heat flux sensor comprising a metal magnetic film on a substrate, the metal magnetic film has a portion with a different composition in an in-plane direction, and is magnetized in a direction with the different composition, the composition of the metal magnetic film changes gradually or stepwise from one end to the other end, The voltage (V Ｌ ) and the voltage (V Ｔ ) and a heat flux sensor characterized by measuring the heat flux from the relationship.

2. A heat flux sensor as described in claim 1, characterized in that the metal magnetic film is a ferromagnetic film or a diamagnetic film.

3. A heat flux sensor as described in claim 1 or 2, characterized in that the metal magnetic film is formed by stacking a ferromagnetic film or a diamagnetic film and a paramagnetic film.

4. A heat flux sensor described in any one of claims 1 to 3, characterized in that the two points where the composition of the metal magnetic film differs differ in the content of the element whose content changes the most by 30 at% or more.

5. A semiconductor device comprising the heat flux sensor according to any one of claims 1 to 4, wherein the metal magnetic film is bonded to a semiconductor substrate.

6. The metal magnetic film of the heat flux sensor is larger than the semiconductor substrate, 6. The semiconductor device according to claim 5, wherein the area of ​​the region where the composition of the metal magnetic film is the same is smaller than that of the semiconductor substrate.

7. A semiconductor device as described in claim 5 or 6, characterized in that the substrate of the heat flux sensor is a heat sink.

8. A method for manufacturing a heat flux sensor according to any one of claims 1 to 4, comprising: The method includes the steps of forming a metal magnetic film on a substrate and magnetizing the formed metal magnetic film, A method for manufacturing a heat flux sensor, characterized in that the film formation process includes a process of using two or more targets with at least different compositions, placing a shutter that partially blocks each target between the substrate and each target, and simultaneously sputtering the two or more targets with different compositions.

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