JP6488202B2 - Magnetoresistive element and electronic device - Google Patents

Description

  The present invention relates to a magnetoresistive element in which a magnetoresistive layer is formed on an insulating substrate (or insulating film), and an electronic device using the magnetoresistive element.

  The magnetoresistive element changes its resistance value according to the strength of the magnetic field. This phenomenon is called a magnetoresistance effect (MR effect). As shown in FIGS. 13A and 13B, the magnetoresistive effect is obtained when the current i flows from the first electrode E1 to the second electrode E2 through the magnetoresistive portion R in the magnetoresistive element MR. This is because carriers in the magnetoresistive portion R receive Lorentz force due to a magnetic field and the conductive path is bent, thereby increasing the resistance value. In many magnetoresistive elements, a single crystal semiconductor substrate (for example, InSb, InGaAs, InAs, etc.) having a high mobility carrier is used to increase magnetic sensitivity (ratio of change in resistance value with respect to change in magnetic field strength). ) Is formed.

  A magnetic field sensor array in which a large number of magnetoresistive elements are arranged in a matrix is also known. Patent Document 1 discloses a magnetic field sensor array using a magnetoresistive element in which a magnetoresistive portion (magnetoresistive layer) is formed on an insulator by patterning a Ni—Fe-based alloy multilayer film. Here, it is also disclosed that a magnetoresistive element is formed on an insulator together with a thin film transistor (TFT).

Japanese Patent Application Laid-Open No. 07-174649

  However, in the case where the magnetoresistive portion is formed on the insulator, since the magnetoresistive portion is amorphous or polycrystalline, the carrier resistance is generally smaller than that of the magnetoresistive portion formed in the single crystal semiconductor substrate. Low mobility and therefore low magnetic sensitivity. On the other hand, a device in which a magnetoresistive portion is formed in a single crystal semiconductor substrate is difficult to use for a large magnetic field sensor array because the size of the single crystal semiconductor substrate is limited.

  This invention is made | formed in view of the reason which concerns, The objective is to provide the magnetoresistive element which forms a magnetoresistive part (magnetoresistive layer) on an insulator, Comprising: High magnetic sensitivity is there.

  In order to achieve the above object, in the magnetoresistive element according to claim 1, when a voltage is applied between the first and second electrodes and the first and second electrodes, a current flows, and a magnetic field A magnetoresistive element comprising a magnetoresistive layer whose resistance value changes according to the strength of the magnetoresistive layer, wherein the magnetoresistive layer is formed by patterning a thin film of amorphous IGZO.

  The magnetoresistive element according to claim 2 is the magnetoresistive element according to claim 1, wherein the first and second electrodes are formed by patterning one metal layer, and the metal layer is The first and second electrodes are deposited after the formation of the magnetoresistive layer, the subsequent deposition and patterning of the interlayer insulating film, and each of the first and second electrodes is one of the layers removed by the patterning of the interlayer insulating film. The insulating film removing portion is in contact with the magnetoresistive layer.

  The magnetoresistive element according to claim 3 is the magnetoresistive element according to claim 2, wherein both the first and second electrodes are formed on the magnetoresistive layer in the groove-shaped interlayer insulating film removing portion. It is characterized by being in contact.

  The magnetoresistive element according to claim 4 is the magnetoresistive element according to claim 2 or 3, further comprising a gate electrode, wherein the gate electrode is formed before the formation of the magnetoresistive layer. The magnetoresistive layer is provided above the gate electrode through a gate insulating film.

  An electronic device according to claim 5 includes the magnetoresistive element according to any one of claims 1 to 4 and a thin film transistor, wherein the thin film transistor includes a drain electrode, a source electrode, and a gate electrode. A channel layer through which a current corresponding to the voltage flows when a voltage is applied between the drain electrode and the source electrode and between the gate electrode and the source electrode, the channel layer comprising: The amorphous IGZO thin film is patterned simultaneously with the magnetoresistive layer.

  The electronic device according to claim 6 is the electronic device according to claim 5, wherein the voltage applied between the magnetoresistive element and the first and second electrodes of the magnetoresistive element is controlled. Magnetic measuring cells having switching elements for magnetoresistive elements of thin film transistors are arranged in a matrix.

  The electronic device according to claim 7 is the electronic device according to claim 6, wherein the magnetic measurement cell is provided between display pixel cells arranged in a matrix, and the display pixel cell is connected to a display element. And a switching element for a display element of the thin film transistor for controlling a voltage applied to the display element.

  According to the present invention, it is possible to provide a magnetoresistive element that forms a magnetoresistive layer on an insulating substrate (or insulating film) and has high magnetic sensitivity.

1A and 1B show a structure of a magnetoresistive element according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 2B is a cross-sectional view taken along line A-A ′ in FIG. FIG. 7 shows a structure of a modified example of the magnetoresistive element, wherein (a) is a plan view and (b) is a cross section taken along line BB′-B ″ -B ′ ″ of (a). FIG. The structure of the further modification of a magnetoresistive element same as the above is shown, Comprising: (a) is a top view, (b) is sectional drawing along the C-C 'line of (a). It is a circuit diagram which shows a structure when measuring the sample of a magnetoresistive element same as the above. It is a characteristic view of two samples of a magnetoresistive element same as the above. It is a characteristic view of two samples of the modification of a magnetoresistive element same as the above. It is a characteristic view when a gate voltage is changed into two kinds about the sample of the further modification of a magnetoresistive element same as the above. It is a characteristic view about the sample of the further modification of a magnetoresistive element same as the above, (a) is a characteristic view when changing gate voltage further from the case of Drawing 7, (b) is a current value and magnetic sensitivity. It is a graph which shows a relationship. It is a characteristic view for the reference of the characteristic of a magnetoresistive element same as the above, (a) shows the characteristic which used the polysilicon for a magnetoresistive layer, (b) is the annealing conditions of a magnetoresistive element same as the above It shows special characteristics obtained by changing etc. 1 shows a structure in which the magnetoresistive element is combined with a thin film transistor, where (a) is a plan view and (b) is a cross-sectional view taken along the line D-D ′ of (a). The example of the electronic device to which the magnetoresistive element same as the above is applied, (a) is a schematic perspective view, (b) is a circuit diagram showing a part of the configuration. It is a circuit diagram which shows the other example of the electronic device to which the magnetoresistive element same as the above is applied. It is explanatory drawing of a magnetoresistive effect, Comprising: (a) is a thing of the situation where there is no magnetic field, (b) is a thing of the situation where there is a magnetic field.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the magnetoresistive element 1 according to the embodiment of the present invention includes a first electrode 2 and an insulating (insulating film) 1b on a substrate 1a such as a resin substrate or a glass substrate. A second electrode 3; and a magnetoresistive layer 4 in which a current flows when a voltage is applied between the first electrode 2 and the second electrode 3, and the resistance value changes according to the strength of the magnetic field. It will be. The magnetoresistive layer 4 is formed by patterning a thin film of amorphous IGZO. The patterning is to form a film into a necessary shape, and usually depends on an etching method, but the method is not limited.

  Amorphous IGZO is an amorphous oxide composed of elements of In, Ga, Zn, and oxygen and having semiconductor properties. When this amorphous IGZO is used for the magnetoresistive layer 4, the magnetoresistive element 1 is provided with a magnetic sensitivity even though the magnetoresistive layer 4 is formed on the insulator 1b, as will be described in detail in an experiment described later. Can be expensive.

  Specifically, the first and second electrodes 2 and 3 are formed by patterning one metal layer (for example, a layer of aluminum or copper). This metal layer is deposited after the formation of the magnetoresistive layer 4 and the subsequent deposition and patterning of the interlayer insulating film 5. The interlayer insulating film 5 is provided with an interlayer insulating film removing portion 5a removed by patterning. In FIG. 1, the interlayer insulating film removal portion 5a is a so-called contact hole. Each of the first and second electrodes 2 and 3 is in contact with the magnetoresistive layer 4 in any one of the interlayer insulating film removal portions 5a.

  Next, a magnetoresistive element 1A obtained by modifying the magnetoresistive element 1 will be described. As shown in FIG. 2, the magnetoresistive element 1 </ b> A includes first and second electrodes 2 and 3 and a magnetoresistive layer 4 similar to the case of the magnetoresistive element 1 described above. . Unlike the case of the magnetoresistive element 1, in the magnetoresistive element 1A, both the first electrode 2 and the second electrode 3 extend from at least the position of the first electrode 2 to the position of the second electrode 3. That is, it is in contact with the magnetoresistive layer 4 in the two groove-like interlayer insulating film removal portions 5Aa. That is, in the magnetoresistive element 1 </ b> A, the interlayer insulating film 5 is continuously removed from the position of the first electrode 2 to the position of the second electrode 3 above the magnetoresistive layer 4.

  The magnetoresistive element 1A can have a higher magnetic sensitivity, as will be described in detail in an experiment described later.

  Next, a magnetoresistive element 1B obtained by further modifying the magnetoresistive element 1 will be described. As shown in FIG. 3, the magnetoresistive element 1 </ b> B includes first and second electrodes 2 and 3 and a magnetoresistive layer 4 similar to the case of the magnetoresistive element 1 described above. . The magnetoresistive element 1 </ b> B further includes a gate electrode 6. The gate electrode 6 is formed before the magnetoresistive layer 4 is formed. The magnetoresistive layer 4 is provided above the gate electrode 6 via the gate insulating film 6A.

  The magnetoresistive element 1B can change the magnetic sensitivity by the voltage (gate voltage) applied to the gate electrode 6, as will be described in detail in an experiment described later. In the magnetoresistive element 1B as well, both the first electrode 2 and the second electrode 3 are removed by at least one groove-like interlayer insulating film extending from the position of the first electrode 2 to the position of the second electrode 3. It is possible to contact the magnetoresistive layer 4 in the part 5Aa.

  An experiment conducted by the inventor for such magnetoresistive elements 1, 1A, 1B will be described below.

As for the magnetoresistive elements 1 and 1A, as shown in FIG. 4A, the second electrode 3 is grounded, and a predetermined voltage Vapp (10 V) is applied to the first electrode 2 by the voltage applying means 7A. The situation where the intensity of B is 0 mT (the situation where there is no magnetic field) and the situation where the intensity of the magnetic field B is 200 mT (the situation where there is a magnetic field) are repeated every 20 seconds, and the current i flowing through the magnetoresistive elements 1 and 1A is It was measured. The magnetic sensitivity was determined by the ratio of the change in the intensity of the magnetic field B changes in resistance value with respect to _{(200mT) (ΔR / R 0} = (i 0 / i 1 -1)). Note that R ₀ is a resistance value in the absence of a magnetic field, i ₀ is a current value in the absence of a magnetic field, and i ₁ is a current value in the presence of a magnetic field.

  FIGS. 5A and 5B show the experimental results for the samples A and B of the magnetoresistive element 1, respectively. The magnetic sensitivity was 2.3% / T for sample A and 1.2% / T for sample B. FIGS. 6A and 6B show experimental results for samples C and D of the magnetoresistive element 1A, respectively. The magnetic sensitivity of sample C was 6.3% / T and sample D was 2.8% / T.

  As for the magnetoresistive element 1B, as shown in FIG. 4 (b), the second electrode 3 is grounded, and a predetermined voltage (gate voltage) Vg is applied to the gate electrode 6 by the voltage applying means 7C. By applying a predetermined voltage Vapp (10V) to the first electrode 2 by the above, a situation where the intensity of the magnetic field B is 0 mT (a situation where there is no magnetic field) and a situation where the intensity of the magnetic field B is 200 mT (a situation where there is a magnetic field) The current i flowing through the magnetoresistive element 1B was measured with an ammeter 7B. The gate voltage Vg was set to + 2V, 0V, and −2V. The method for obtaining the magnetic sensitivity is as described above for the magnetoresistive elements 1 and 1A.

7A, 7B, and 8A show the experimental results for the sample E of the magnetoresistive element 1B. Magnetic sensitivity was 3.4% / T when Vg was + 2V, 6.0% / T when Vg was 0V, and 10.4% / T when Vg was -2V. FIG. 8 (b) shows that the magnetic sensitivity changes according to the gate voltage Vg using the experimental results shown in FIGS. 7 (a), 7 (b) and 8 (a). The horizontal axis represents the current i flowing through the magnetoresistive element 1B (specifically, i ₀ in the absence of a magnetic field), and the vertical axis represents the magnetic sensitivity.

  Thus, high magnetic sensitivity is recognized in magnetoresistive element 1, 1A, 1B. On the other hand, in the reference experiment conducted by the inventor of the present application, when polysilicon (p-Si) is used for the magnetoresistive layer 4 as shown in FIG. Or the magnetization sensitivity was extremely low.

  In addition, the magnetoresistive element 1 </ b> A has higher magnetic sensitivity than the magnetoresistive element 1. In the magnetoresistive element 1B, the magnetic sensitivity is changed by the voltage (gate voltage) applied to the gate electrode 6.

  In addition, about this magnetoresistive element 1 (or 1A, 1B), this inventor manufactures on various conditions and continues evaluation. Among them, depending on annealing conditions and the like, as shown in FIG. 9B, the characteristic that the current i in the presence of the magnetic field is larger than i in the absence of the magnetic field, that is, the magnetoresistive effect having a negative coefficient. A sample showing is obtained. This characteristic is a sign of the same coefficient as the giant magnetoresistance effect. Thus, a magnetoresistive element having a magnetoresistive layer made of an amorphous IGZO thin film can be expected to further improve the magnetic sensitivity in the future.

  The magnetoresistive element 1 (or 1A, 1B) described above can be applied to various electronic devices in combination with the thin film transistor 8. As shown in FIG. 10, the thin film transistor 8 includes a drain electrode 9, a source electrode 10, a gate electrode 11, a region between the drain electrode 9 and the source electrode 10, and a gate electrode 11 and a source electrode on a substrate 1 a. When a voltage is applied between 10, a channel layer 12 in which a current corresponding to the voltage flows is provided. The channel layer 12 is formed simultaneously with the magnetoresistive layer 4 by patterning a thin film of amorphous IGZO. In FIG. 10, the magnetoresistive element 1 </ b> A is shown in combination with the thin film transistor 8. Reference numeral 11A denotes a gate insulating film.

  Thus, the magnetoresistive element 1 (or 1A, 1B) combined with the thin film transistor 8 is useful for an electronic device 13 as shown in FIG. The electronic device 13 is formed as a magnetic field sensor array on a substrate 1a such as a resin substrate or a glass substrate in which a large number of magnetic measurement cells 13A are arranged in a matrix. Each magnetic measurement cell 13A has a magnetoresistive element switching element 8A of the thin film transistor 8 together with the magnetoresistive element 1 (or 1A, 1B) as shown in FIG. The magnetoresistive element switching element 8A controls the voltage applied between the first electrode 2 and the second electrode 3 of the magnetoresistive element 1 (or 1A, 1B). The thin film transistor 8 can also be used as an element of the control circuit 13B that controls the magnetic measurement cell 13A. The substrate 1a can have a large size, and can measure a magnetic field in a wide area. The electronic device 13 is controlled by, for example, a computer (not shown) via an electronic device controller 14 that directly controls the electronic device 13.

  In addition, the electronic device 13 can be modified so that the above-described magnetic measurement cells 13A are provided between the display pixel cells 13C, and a large number of magnetic measurement cells 13A are arranged in a matrix together with the large number of display pixel cells 13C. The display pixel cell 13C of the electronic device 13 'includes a display element 15 and a display element switching element 8C of the thin film transistor 8, as shown in FIG. The display element 15 is a liquid crystal element or the like. The display element switching element 8 </ b> C controls the voltage applied to the display element 15. The electronic device 13 ′ can perform pen input on the display panel by detecting the position by the magnetoresistive element 1 (or 1A, 1B) using a pen having a magnet. Note that FIG. 12 shows a configuration in which one column of magnetic measurement cells 13A is provided for every three columns of display pixel cells 13C.

  Although the magnetoresistive element according to the embodiment of the present invention has been described above, the present invention is not limited to the one described in the embodiment, and various design changes within the scope of the matters described in the claims. Is possible.

DESCRIPTION OF SYMBOLS 1, 1A, 1B Magnetoresistive element 2 1st electrode 3 2nd electrode 4 Magnetoresistive layer 5 Interlayer insulating film 6 Gate electrode of magnetoresistive element 8 Thin-film transistor 9 Drain electrode 10 Source electrode 11 Gate electrode of thin-film transistor 12 Channel layer 13 , 13 'electronic device

Claims (7)

A first and second electrode; and a magnetoresistive layer in which a current flows when a voltage is applied between the first and second electrodes, and a resistance value changes according to the strength of the magnetic field. In the magnetoresistive element,
The magnetoresistive element, wherein the magnetoresistive layer is formed by patterning a thin film of amorphous IGZO. The magnetoresistive element according to claim 1,
The first and second electrodes are formed by patterning one metal layer,
The metal layer is deposited after the formation of the magnetoresistive layer, the subsequent deposition and patterning of the interlayer insulating film,
The magnetoresistive element according to claim 1, wherein the first and second electrodes are in contact with the magnetoresistive layer in any one of the interlayer insulating film removal portions removed by the patterning of the interlayer insulating film. The magnetoresistive element according to claim 2,
The first and second electrodes are both in contact with the magnetoresistive layer in one groove-shaped interlayer insulating film removing portion. The magnetoresistive element according to claim 2 or 3,
A gate electrode;
The gate electrode is formed before the formation of the magnetoresistive layer;
The magnetoresistive element, wherein the magnetoresistive layer is provided above the gate electrode through a gate insulating film. The magnetoresistive element according to any one of claims 1 to 4,
A thin film transistor,
When a voltage is applied between the drain electrode, the source electrode, and the gate electrode, and between the drain electrode and the source electrode, and between the gate electrode and the source electrode, the thin film transistor has a current corresponding to the voltage. A channel layer through which
The channel layer is formed simultaneously with the magnetoresistive layer by patterning the amorphous IGZO thin film. The electronic device according to claim 5.
A magnetic measurement cell having the magnetoresistive element and a switching element for the magnetoresistive element of the thin film transistor for controlling a voltage applied between the first and second electrodes of the magnetoresistive element is arranged in a matrix An electronic device characterized by being made. The electronic device according to claim 6.
The magnetic measurement cell is provided between display pixel cells arranged in a matrix,
The display pixel cell includes a display element and a switching element for a display element of the thin film transistor that controls a voltage applied to the display element.