JP6215001B2 - Magnetoresistive element, magnetic sensor device, and method of manufacturing magnetoresistive element - Google Patents

Description

  The present invention relates to a magnetoresistive element having a magnetoresistive film formed on a substrate, a magnetic sensor device including the magnetoresistive element, and a method of manufacturing the magnetoresistive element.

  In a rotary encoder that detects the rotation of a rotating body relative to a fixed body, for example, a magnetic sensor device is provided that includes a magnet on the rotating body side and a magnetoresistive element on the fixed body side. In such a magnetoresistive element, a magnetoresistive film made of Ni—Fe or the like is formed on one surface of a substrate, and an output output from a two-phase (A phase and B phase) bridge circuit constituted by the magnetoresistive film. Based on this, an angular velocity, an angular position, and the like of the rotating body are detected (see, for example, Patent Document 1).

  In order to manufacture such a magnetoresistive element, a magnetoresistive film is formed on one surface of the substrate while the substrate is heated in a vacuum chamber, and then the magnetoresistive film is patterned. In such a manufacturing method, when the surface of the magnetoresistive film is oxidized in contact with air, the magnetoresistive film becomes thinner by the thickness of the oxide film, and the rate of change in resistance due to the magnetoresistive effect is reduced. In particular, in order to increase the sensitivity of the magnetoresistive element, the magnetoresistive film is formed thin, so that the decrease in the resistance change rate due to the formation of the oxide film becomes a big problem. Therefore, nitrogen gas is introduced into the vacuum chamber to lower the temperature of the magnetoresistive film and the temperature in the vacuum chamber, and then the vacuum chamber is opened to the atmosphere and the substrate is taken out from the vacuum chamber. However, even if the above method is adopted, the surface of the magnetoresistive film cannot be sufficiently prevented from being oxidized.

  On the other hand, a technique for preventing the surface of the magnetoresistive film from being oxidized when the resist mask used for patterning the magnetoresistive film is removed by plasma ashing using a mixed gas of oxygen gas and nitrogen gas has been proposed. . In such a technique, after a barrier layer made of a nonmagnetic metal is laminated on the surface of a magnetoresistive film such as Ni—Co or Ni—Fe, a resist mask is formed, and the magnetoresistive film and the barrier layer are patterned together ( Patent Document 2). Further, in Patent Document 2, since the thickness of the magnetoresistive film and the thickness of the barrier layer are equivalent, the resistance of the barrier layer can be obtained by using Mo—Si, Ti—W, Ti—N, or the like for the barrier layer. Is larger than the resistance of the magnetoresistive film.

JP 2012-118000 A JP 2009-105208 A

  However, as in the configuration described in Patent Document 2, when the thickness of the magnetoresistive film and the thickness of the barrier layer are equal, it is necessary to use a nonmagnetic metal having a large specific resistance as the barrier layer. The constraints are great. In addition, when the barrier layer is thick, even if the barrier layer is formed of a nonmagnetic metal material having a large non-resistance value, the resistance of the barrier layer is reduced and the rate of change in resistance due to the magnetoresistive effect is reduced. Resulting in.

  In view of the above problems, an object of the present invention is to provide a magnetoresistive element having a high rate of change in resistance due to the magnetoresistive effect even when the surface of the magnetoresistive film is prevented by a barrier layer, and a magnetic device including the magnetoresistive element. It is providing the sensor apparatus and the manufacturing method of the said magnetoresistive element.

In order to solve the above problems, a magnetoresistive element according to the present invention includes a substrate, a magnetoresistive film formed on one side of the substrate, and a surface of the magnetoresistive film opposite to the substrate. It is stacked with a magnetoresistive film and the same pattern, possess a barrier layer having a thickness from the magnetoresistive film is a thin non-magnetic metal film, wherein the barrier layer is characterized by containing aluminum as its main component.

A method of manufacturing a magnetoresistive element according to the present invention includes a magnetoresistive film forming step of forming a magnetoresistive film on one side of a substrate, and a surface of the magnetoresistive film without contacting the magnetoresistive film with an oxidizing atmosphere. A barrier layer forming step of forming a barrier layer made of a nonmagnetic metal film thinner than the magnetoresistive film, a mask forming step of forming an etching mask on the surface of the barrier layer, and the barrier layer on the surface of the barrier layer. possess an etching process of etching said magnetoresistive film and said barrier layer in a state of forming an etching mask, an etching mask removing step of removing the etch mask, wherein the barrier layer is mainly composed of aluminum It is characterized by.

In the present invention, after the magnetoresistive film is formed, a barrier layer is laminated on the surface of the magnetoresistive film without contacting the magnetoresistive film with the oxidizing atmosphere, and in this state, the magnetoresistive film and the barrier layer are formed. . For this reason, it is possible to prevent the surface of the magnetoresistive film from being oxidized. For this reason, the resistance change rate can be improved. Further, since the thickness of the barrier layer is thinner than that of the magnetoresistive film, the resistance of the barrier layer is large even if no great restriction is imposed on the nonmagnetic material used for the barrier layer. For this reason, even when a barrier layer is laminated on the magnetoresistive film, an adverse effect on the rate of change in resistance can be prevented, and the advantages resulting from the prevention of oxidation can be utilized. Therefore, even when the surface of the magnetoresistive film is prevented by the barrier layer, a magnetoresistive element having a high resistance change rate due to the magnetoresistive effect can be obtained. Moreover, since a barrier layer has aluminum as a main component, a barrier layer can be formed with a comparatively cheap nonmagnetic metal.

  In the present invention, the barrier layer preferably has a thickness of 0.5 nm to 2.0 nm. In the present invention, the thickness of the barrier layer is preferably 1.0 nm. With such a film thickness, the resistance of the barrier layer is large regardless of the type of nonmagnetic material used for the barrier layer. For this reason, even when a barrier layer is laminated on the magnetoresistive film, an adverse effect on the rate of change in resistance can be prevented, and the advantages resulting from the prevention of oxidation can be utilized.

  In the present invention, it is preferable that a functional layer made of the same metal material as the barrier layer is formed on the substrate. According to such a configuration, even if a barrier layer is added, the type of metal material formed on the substrate does not change. Therefore, the barrier layer can be formed using the target used for forming the functional layer.

  In the present invention, the thickness of the magnetoresistive film is preferably 10 nm to 80 nm.

  The magnetoresistive element to which the present invention is applied is used in a magnetic sensor device or the like.

  In the present invention, after the magnetoresistive film forming step is performed in a vacuum chamber, the barrier layer forming step is preferably performed in the vacuum chamber without introducing an oxidizing gas into the vacuum chamber.

  In the present invention, after performing the magnetoresistive film forming step, an annealing step of heating the magnetoresistive film at a temperature higher than the film forming temperature of the magnetoresistive film in the magnetoresistive film forming step in a non-oxidizing atmosphere. Preferably it is done. According to such a configuration, it is possible to improve the resistance change rate. In addition, when the annealing process is performed without the barrier layer, hysteresis occurs in the resistance change rate. However, in the present invention, since the barrier layer is provided, the resistance change rate is improved even if the resistance change rate is improved by the annealing process. It is possible to suppress the occurrence of hysteresis in the rate of change.

  In the present invention, the annealing step is preferably performed after the etching mask removing step. According to this configuration, since the barrier layer is formed on the magnetoresistive film and the annealing process is performed after the magnetoresistive film and the barrier layer are patterned, the strain of the magnetoresistive film can be efficiently reduced. .

  In the present invention, after the magnetoresistive film is formed, a barrier layer is laminated on the surface of the magnetoresistive film without contacting the magnetoresistive film with the oxidizing atmosphere, and in this state, the magnetoresistive film and the barrier layer are formed. . For this reason, it is possible to prevent the surface of the magnetoresistive film from being oxidized. For this reason, the resistance change rate can be improved. Further, since the thickness of the barrier layer is thinner than that of the magnetoresistive film, the resistance of the barrier layer is large even if no great restriction is imposed on the nonmagnetic material used for the barrier layer. For this reason, even when the barrier layer is laminated on the magnetoresistive film, it is possible to suppress the decrease in the resistance change rate due to the magnetoresistive effect.

It is explanatory drawing which shows the principle of the magnetic sensor apparatus provided with the magnetoresistive element to which this invention is applied, and a rotary encoder. It is explanatory drawing of the electrical connection structure of the magnetoresistive film | membrane of the magnetoresistive element to which this invention is applied. It is explanatory drawing of the magnetoresistive element to which this invention is applied. It is process sectional drawing which shows the manufacturing method of the magnetoresistive element to which this invention is applied. It is explanatory drawing which shows schematic structure of the temperature control part comprised in the control part of the magnetic sensor apparatus to which this invention is applied. It is a graph which shows the evaluation result regarding the resistance change rate of the magnetoresistive element to which this invention is applied. It is a graph which shows the hysteresis of the magnetoresistive effect of the magnetoresistive element to which this invention is applied. It is a graph which shows the hysteresis of the magnetoresistive effect of the magnetoresistive element which concerns on a comparative example. It is a graph which shows the hysteresis of the magnetoresistive effect of another magnetoresistive element to which this invention is applied.

  Embodiments of a magnetoresistive element, a magnetic sensor device, and a rotary encoder to which the present invention is applied will be described below with reference to the drawings. In the rotary encoder, when detecting the rotation of the rotating body relative to the fixed body, the fixed body is provided with a magnet, the rotating body is provided with a magnetoresistive element, and the fixed body is provided with a magnetoresistive element. Any of the configurations in which the magnet is provided may be adopted. However, in the following description, the description will focus on the configuration in which the magnetic sensor device is provided in the fixed body and the magnet is provided in the rotating body.

(Configuration of magnetic sensor device)
FIG. 1 is an explanatory diagram showing the principle of a magnetic sensor device 10 including a magnetoresistive element 4 to which the present invention is applied, and a rotary encoder 1. FIGS. 1 (a), (b), and (c) are magnetoresistive elements. FIG. 4 is an explanatory diagram of a signal processing system for the element 4 and the like, an explanatory diagram of a signal output from the magnetoresistive element 4, and an explanatory diagram showing a relationship between the signal and the angular position (electrical angle) of the rotating body 2. FIG. 2 is an explanatory diagram of an electrical connection structure of the magnetoresistive films 41 to 44 of the magnetoresistive element 4 to which the present invention is applied.

  A rotary encoder 1 shown in FIG. 1 is a device that magnetically detects rotation around an axis (rotation axis) of a rotating body 2 with respect to a fixed body (not shown) by a magnetic sensor device 10, and the fixed body is a motor. The rotating body 2 is fixed to a frame or the like of the device, and is used in a state of being connected to a rotation output shaft or the like of the motor device. On the side of the rotating body 2, a magnet 20 is held that directs the magnetized surface 21 in which the N pole and the S pole are magnetized one by one in the circumferential direction to one side in the rotation axis direction L. It rotates around the rotation axis integrally with the rotating body 2.

  On the fixed body side, there is a magnetic sensor device 10 including the magnetoresistive element 4 facing the magnetized surface 21 of the magnet 20 on one side in the rotation axis direction L, a control unit 90 that performs processing to be described later, and the like. Is provided. In addition, the magnetic sensor device 10 includes a first hall element 61 and a second hall element 62 located at a position that is shifted by 90 ° in the circumferential direction with respect to the first hall element 61 at a position facing the magnet 20. And.

  The magnetoresistive element 4 includes a two-phase magnetoresistive film (A phase (SIN) magnetoresistive film and B phase (COS) magnetism) having a phase difference of 90 ° with respect to the phase of the substrate 40 and the magnet 20. A magnetoresistive element. In the magnetoresistive element 4, the A phase magnetoresistive film includes a + A phase (SIN +) magnetoresistive film 43 that detects movement of the rotating body 2 with a phase difference of 180 °, and a −A phase (SIN−) magnetism. The B-phase magnetoresistive film includes a + B-phase (COS +) magnetoresistive film 44 that detects movement of the rotating body 2 with a phase difference of 180 °, and a −B-phase (COS−) magnetoresistive film. A magnetoresistive film 42 is provided.

  The + A-phase magnetoresistive film 43 and the -A-phase magnetoresistive film 41 constitute the bridge circuit shown in FIG. 2A, and one end is connected to the A-phase power supply terminal VccA and the other end is It is connected to the A phase ground terminal GNDA. An output terminal + A from which the + A phase is output is provided at the midpoint position of the + A phase magnetoresistive film 43, and an output from which the −A phase is output at the midpoint position of the −A phase magnetoresistive film 41. Terminal -A is provided. Similarly to the + A phase magnetoresistive film 44 and the −A phase magnetoresistive film 41, the + B phase magnetoresistive film 44 and the −B phase magnetoresistive film 42 also constitute the bridge circuit shown in FIG. One end is connected to the B-phase power supply terminal VccB, and the other end is connected to the B-phase ground terminal GNDB. An output terminal + B from which the + B phase is output is provided at the midpoint position of the + B phase magnetoresistive film 44, and an output from which the −B phase is output at the midpoint position of the −B phase magnetoresistive film 42. Terminal -B is provided. In FIG. 2, for convenience, the A-phase power supply terminal VccA and the B-phase power supply terminal VccB are shown, but the A-phase power supply terminal VccA and the B-phase power supply terminal VccB are common. May be. For convenience, FIG. 2 shows the A-phase ground terminal GNDA and the B-phase ground terminal GNDB, but the A-phase ground terminal GNDA and the B-phase ground terminal GNDB are common. May be.

  In the magnetic sensor device 10 and the rotary encoder 1 of the present embodiment, the amplifying circuits 91, 92, 95, and 96 and the amplifying circuits for the magnetoresistive element 4, the first hall element 61, and the second hall element 62 are provided. A control unit 90 including a CPU (arithmetic circuit) that performs interpolation processing and various arithmetic processing on the sine wave signals sin and cos output from 91, 92, 95, and 96 is configured. Based on the outputs from the 1 Hall element 61 and the second Hall element 62, the rotational angle position of the rotating body 2 with respect to the fixed body is obtained.

More specifically, in the rotary encoder 1, when the rotating body 2 rotates once, the magnetoresistive element 4 outputs the sine wave signals sin and cos shown in FIG. Therefore, after the sine wave signals sin and cos are amplified by the amplifier circuits 91 and 92, the control unit 90 obtains the Lissajous diagram shown in FIG. 1C, and θ = tan ⁻¹ (sin / Cos), the angular position θ of the rotation output shaft can be obtained. In the present embodiment, the first Hall element 61 and the second Hall element 62 are arranged at a position shifted by 90 ° from the center of the magnet 20. For this reason, it can be understood from the combination of the outputs of the first Hall element 61 and the second Hall element 62 which section of the sine wave signal sin or cos the current position is located. Accordingly, the rotary encoder 1 generates absolute angular position information of the rotating body 2 based on the detection result of the magnetoresistive element 4, the detection result of the first Hall element 61, and the detection result of the second Hall element 62. The absolute operation can be performed.

(Planar configuration of the magnetoresistive element 4)
FIG. 3 is an explanatory diagram of the magnetoresistive element 4 to which the present invention is applied, and FIGS. 3A and 3B are an explanatory diagram showing a planar configuration of the magnetoresistive element 4 and an explanatory diagram showing a cross-sectional configuration. . FIG. 3B schematically shows the layer structure of the magnetoresistive films 41 to 44, the temperature monitoring resistive film 47 (functional layer), and the heating resistive film 48 (functional layer). Further, in FIG. 3A, the temperature monitoring resistance film 47 is indicated by a downward sloping line, and the heating resistance film 48 is indicated by a right upward slanting line.

  As shown in FIG. 3A, in the magnetic sensor device 10 and the rotary encoder 1 of this embodiment, the magnetoresistive element 4 includes a substrate 40 and magnetoresistive films 41 to 44 formed on one surface 40a of the substrate 40. The magnetoresistive films 41 to 44 constitute a circular magnetosensitive region 45 in the center of the substrate 40 by portions extending while being folded back. In this embodiment, the substrate 40 is a silicon substrate having a quadrangular planar shape.

  A wiring portion extends integrally from the magnetoresistive films 41 to 44, and an A-phase power supply terminal VccA, an A-phase ground terminal GNDA, and an output terminal for + A-phase output are provided at the ends of the wiring portions. + A, -A phase output terminal -A, B phase power supply terminal VccB, B phase ground terminal GNDB, + B phase output terminal + B, and -B phase output terminal -B Is provided.

  In the magnetoresistive element 4 of this embodiment, the temperature monitoring resistance film 47 and the heating resistance film 48 are formed on the one surface 40 a side of the substrate 40. Here, the heating resistance film 48 extends in a square frame shape along the side of the substrate 40 to form a closed loop, and surrounds the entire region where the magnetoresistive films 41 to 44 are formed. . For this reason, the heating resistance film 48 and the magnetoresistive films 41 to 44 are formed in regions shifted in the in-plane direction of the substrate 40 and do not overlap in a plan view. In addition, a wiring portion 481 extends from one of two opposing side portions of the heating resistance film 48, and a power supply terminal VccH for supplying power to the heating resistance film 48 is formed at the end thereof. . In contrast, the end of the wiring portion 482 extending from the other of the two side portions is connected to the A-phase ground terminal GNDA. Therefore, the A-phase ground terminal GNDA is also used as the ground terminal GNDH for the heating resistance film 48. Here, the connection position between the wiring part 481 and the heating resistance film 48 and the connection position between the wiring part 482 and the heating resistance film 48 are point-symmetrical with respect to the magnetosensitive region 45. Therefore, the length of the heating resistance film 48 when it is turned clockwise from the connection position between the wiring portion 481 and the heating resistance film 48 toward the connection position between the wiring portion 482 and the heating resistance film 48, and the wiring portion 481. The heating resistance film 48 is equal in length when it is turned counterclockwise from the connection position of the heating resistance film 48 toward the connection position of the wiring portion 482 and the heating resistance film 48.

  The temperature monitoring resistance film 47 is provided in the vicinity of one of the four corners of the heating resistance film 48 in the inner region of the heating resistance film 48. Located between. The temperature monitoring resistance film 47 has a planar shape extending while being folded a plurality of times. For this reason, even if the occupation area is small, the resistance film 47 for temperature monitoring can be formed long. Here, the temperature monitoring resistance film 47 partially overlaps the wiring portion of the magnetoresistive film 44, but is formed in a region shifted in the in-plane direction of the substrate 40 from the magnetosensitive region 45. It does not overlap with the magnetic region 45. A temperature monitoring power supply terminal VccS is formed at one end of the temperature monitoring resistance film 47. The other end of the temperature monitoring resistance film 47 is connected to a B-phase ground terminal GNDB. For this reason, the B-phase ground terminal GNDB is also used as the ground terminal GNDS for the temperature monitoring resistance film 47.

(Cross-sectional configuration of magnetoresistive element 4)
As shown in FIG. 3B, in the magnetoresistive element 4 of the present embodiment, a first insulating film 51 made of a silicon oxide film, a second insulating film 52 made of a silicon oxide film, A third insulating film 53 made of polyimide resin or the like is sequentially formed.

  Here, the magnetoresistive films 41 to 44 are formed between the substrate 40 and the first insulating film 51. The temperature monitoring resistance film 47 and the heating resistance film 48 are formed between the first insulating film 51 and the second insulating film 52. For this reason, the magnetoresistive films 41 to 44 are formed in a layer different from the temperature monitoring resistance film 47 and the heating resistance film 48 via the first insulating film 51, and the temperature monitoring resistance film 47 and the heating resistance film 48 are formed. The film 48 is formed in the same layer.

  The magnetoresistive films 41 to 44 and the heating resistive film 48 are formed between the substrate 40 and the first insulating film 51, and the temperature monitoring resistive film 47 is formed between the first insulating film 51 and the second insulating film 52. A structure formed between layers may be employed.

  In this embodiment, the magnetoresistive films 41 to 44 are magnetic films such as a Ni—Fe film, Ni—Co, and Ni—Fe—Co formed by a vapor deposition method. Each of the temperature monitoring resistance film 47 and the heating resistance film 48 is a non-magnetic film formed by vapor deposition, such as titanium (Ti) film, Ti alloy film, aluminum (Al) film, Al alloy film, titanium, etc. And a film mainly composed of aluminum. In this embodiment, the temperature monitoring resistance film 47 and the heating resistance film 48 are made of a Ti film.

(Configuration of barrier layer)
As shown in FIG. 3B, in the magnetoresistive element 4 of this embodiment, the surface of the magnetoresistive films 41 to 44 (surface opposite to the substrate 40) has the same pattern as the magnetoresistive films 41 to 44. Layers 71 to 74 are laminated. The barrier layers 71 to 74 are made of a nonmagnetic metal film that is thinner than the magnetoresistive films 41 to 44. For example, the barrier layers 71 to 74 are made of a film containing aluminum as a main component, such as an Al film or an Al alloy film. Moreover, the thickness of the magnetoresistive films 41 to 44 is, for example, 10 nm to 80 nm, and the thickness of the barrier layers 71 to 74 is, for example, 0.5 nm to 2.0 nm. In this embodiment, the thickness of the barrier layers 71 to 74 is 1.0 nm.

  Here, the barrier layers 71 to 74 have a function of preventing the surfaces of the magnetoresistive films 41 to 44 from being oxidized when the magnetoresistive element 4 is manufactured by the method described with reference to FIG. Yes.

(Manufacturing method of magnetoresistive element 4)
FIG. 4 is a process sectional view showing a method of manufacturing the magnetoresistive element 4 to which the present invention is applied. In order to manufacture the magnetoresistive element 4 of this embodiment, first, as shown in FIG. 4A, after preparing the substrate 40, the substrate 40 is deposited in the magnetoresistive film forming step shown in FIG. 4B. Into the vacuum chamber. Next, the vacuum chamber is evacuated and the substrate 40 is heated to a temperature of 300 to 400 ° C., for example, 355 ° C. In this state, the Ni—Fe film, Ni—Co, and Ni—Fe are heated. A magnetoresistive film 49 made of a magnetic film such as Co is formed by vapor deposition. The thickness of the magnetoresistive film 49 is, for example, 10 nm to 80 nm. In this embodiment, the thickness of the magnetoresistive film 49 is 35 nm.

Next, in the barrier layer forming step shown in FIG. 4C, the magnetoresistive film 49 is formed on the surface of the magnetoresistive film 49 from a nonmagnetic metal film thinner than the magnetoresistive film 49 without bringing it into contact with the oxidizing atmosphere. A barrier layer 79 is formed by vapor deposition. More specifically, the vapor deposition material can be used without leaving the atmosphere (oxidizing atmosphere) in the vacuum chamber in which the magnetoresistive film 49 is formed and leaving the substrate 40 in a vacuum state without carrying out the substrate 40 from the vacuum chamber. Only a change is made, and a barrier layer 79 is formed on the surface of the magnetoresistive film 49. The barrier layers 71 to 74 are made of a film containing aluminum as a main component. Further, the thickness of the barrier layer 79 is, for example, 0.5 nm to 2.0 nm, and in this embodiment, the thickness of the barrier layer 79 is 1.0 nm.

  Next, after the substrate 40 on which the magnetoresistive film 49 and the barrier layer 79 are formed is unloaded from the vacuum chamber, a mask forming process shown in FIG. 4D is performed. In the mask forming step, a photosensitive resin is applied to the surface of the barrier layer 79, and then exposed and developed, and an etching mask 89 made of a resist mask is formed at positions where the magnetoresistive films 41 to 44 are to be formed.

  Next, in the etching step shown in FIG. 4E, the magnetoresistive film 49 and the barrier layer 79 are etched with the etching mask 89 formed on the surface of the barrier layer 79. As a result, the magnetoresistive film 49 is patterned into the magnetoresistive films 41 to 44, and the barrier layer 79 is patterned into the barrier layers 71 to 74. In this etching process, either dry etching or wet etching may be used.

  Next, an etching mask removing process shown in FIG. 4F is performed to remove the etching mask 89. In the etching mask removing step, either plasma ashing using a gas containing oxygen gas or wet ashing may be used.

  Next, as shown in FIG. 3B, after forming a first insulating film 51 made of a silicon oxide film, a temperature monitoring resistance film 47 and a heating resistance film 48 are formed, and then, from the silicon oxide film A second insulating film 52 and a third insulating film 53 made of polyimide resin or the like are sequentially formed. In this embodiment, when the temperature monitoring resistance film 47 and the heating resistance film 48 are formed, a film mainly composed of titanium or aluminum, such as a Ti film, a Ti alloy film, an Al film, or an Al alloy film, is deposited. Then, patterning is performed using a resist mask.

  In this embodiment, after the magnetoresistive film forming step shown in FIG. 4B is performed, a temperature higher than the film forming temperature of the magnetoresistive film 49 in the magnetoresistive film forming step in a non-oxidizing atmosphere, for example, 385 It is preferable to perform an annealing step of heating the magnetoresistive film 49 (the magnetoresistive films 41 to 44) for about 30 minutes at a temperature of ° C. In this embodiment, after the etching mask removing process is performed, an annealing process is performed before the first insulating film 51 is formed.

(Temperature adjustment of magnetoresistive element 4)
FIG. 5 is an explanatory diagram showing a schematic configuration of a temperature control unit configured in the control unit 90 of the magnetic sensor device 10 to which the present invention is applied.

  As shown in FIG. 5, the control unit 90 of the magnetic sensor device 10 according to the present embodiment includes a temperature control unit that controls power supply to the heating resistance film 48 based on the resistance change of the temperature monitoring resistance film 47. ing. More specifically, a resistor 81 is connected to the temperature monitoring power supply terminal VccS of the temperature monitoring resistor film 47, and the side of the resistor 81 opposite to the side where the temperature monitoring resistor film 47 is connected is the power source. It is connected to the terminal VccS0. A temperature monitoring ground terminal GNDS is provided on the opposite side of the temperature monitoring resistor film 47 to which the resistor 81 is connected. The temperature monitoring resistor film 47 and the resistor 81 are connected to the power supply terminal VccS0 and the ground terminal. It is connected in series with GNDS.

  A switching element 83 made of a bipolar transistor is connected to the heating power supply terminal VccH of the heating resistance film 48, and the opposite side of the switching element 83 to which the heating resistance film 48 is connected is connected to the power supply terminal VccH0. It is connected. A heating ground terminal GNDH is provided on the opposite side of the heating resistive film 48 to which the switching element 83 is connected. The heating resistive film 48 and the switching element 83 are composed of a power supply terminal VccH0 and a ground terminal. It is connected in series with GNDH.

  Here, the temperature monitoring resistor film 47 and the resistor 81 are inputted to one terminal of the operational amplifier 82, and the other terminal of the operational amplifier 82 has a voltage Vo serving as a threshold for turning on and off the switching element 83. Is entered. In this state, when the temperature of the substrate 40 decreases, the resistance value of the temperature monitoring resistance film 47 decreases, and the voltage at the connection point divided by the resistor 81 decreases. At that time, when the voltage becomes lower than the threshold value Vo inputted to the other terminal of the operational amplifier 82, the operational amplifier 82 is turned on and the switching element 83 is turned on, so that power is supplied to the heating resistance film 48.

  In this state, when the temperature of the substrate 40 increases, the resistance value of the temperature monitoring resistance film 47 increases, and the voltage at the connection point with the resistor 81 increases. At that time, when the voltage becomes higher than the threshold value Vo inputted to the other terminal of the operational amplifier 82, the operational amplifier 82 is turned off and the switching element 83 is turned off, so that the power supply to the heating resistive film 48 is stopped. Therefore, the temperature of the magnetoresistive element 4 (the magnetoresistive films 41 to 44) is maintained at a predetermined temperature defined by the resistance values of the temperature monitoring resistor film 47 and the resistor 81, and the like.

(Evaluation results)
FIG. 6 is a graph showing an evaluation result regarding the resistance change rate of the magnetoresistive element 4 to which the present invention is applied. FIGS. 6A and 6B show a case where an aluminum film is used as the barrier layers 71 to 74. A graph showing the relationship between the thickness of the aluminum film and the rate of change in resistance (ΔR / R), and the relationship between the annealing time and the rate of change in resistance (ΔR / R) when an aluminum film is used as the barrier layers 71 to 74 It is a graph to show. In FIG. 6A, the result when the annealing step is not performed is indicated by a dotted line L0, and the result when the annealing step (temperature = 385 ° C., time = about 30 minutes) is performed is indicated by a solid line L1. is there.

  FIG. 7 is a graph showing the magnetoresistive effect hysteresis of the magnetoresistive element 4 to which the present invention is applied. FIGS. 7A and 7B show an aluminum film having a thickness of 1.0 nm as the barrier layers 71 to 74. When the annealing process is not performed, and when the annealing process (temperature = 385 ° C., time = about 30 minutes) is performed using a 1.0 nm-thickness aluminum film as the barrier layers 71 to 74. It is a graph.

  FIG. 8 is a graph showing the hysteresis of the magnetoresistive effect of the magnetoresistive element 4 according to the comparative example. FIGS. 8A and 8B do not perform the annealing process without forming the barrier layers 71 to 74. And a graph when the annealing step (temperature = 385 ° C., time = about 30 minutes) is performed without forming the barrier layers 71-74.

  FIG. 9 is a graph showing the magnetoresistive effect hysteresis of another magnetoresistive element 4 to which the present invention is applied. A titanium film having a thickness of 1.0 nm is used as the barrier layers 71 to 74, and an annealing process (temperature = 385). It is a graph at the time of performing (degreeC, time = about 30 minutes).

  The rate of change in resistance (ΔR / R) is based on the resistance value when the magnetic flux density is 0 mT. FIGS. 7, 8 and 9 show the rate of change in resistance (ΔR / R) when the magnetic flux density is changed to 0 mT, −15 mT, 0 mT, +15 mT, and 0 mT.

  First, as can be seen from FIG. 6A, when the barrier layers 71 to 74 are provided, the barrier layers 71 to 74 are not provided (Al film thickness is 0 nm) regardless of the annealing process. As a result, the rate of resistance change (ΔR / R) increases. However, since the rate of change in resistance (ΔR / R) decreases if the barrier layers 71 to 74 are too thick, the thickness of the barrier layers 71 to 74 is 0.5 nm to 2.0 nm. It is preferably 0 nm.

  Further, in the case where the barrier layers 71 to 74 are provided and in the case where the barrier layers 71 to 74 are not provided, when the annealing process is performed, the resistance change rate (ΔR / R) is when the annealing process is not performed. It becomes larger than that. However, when the annealing process is performed when the barrier layers 71 to 74 are too thick, the resistance change rate (ΔR / R) is decreased as compared with the case where the annealing process is not performed. Therefore, it is preferable to perform the annealing step when the thickness of the barrier layers 71 to 74 is 0.5 nm to 2.0 nm.

  In addition, when the annealing temperature is 385 ° C., the annealing process time increases from 0 minutes to 30 minutes, and the resistance change rate (ΔR / R) increases as the time increases, but when it exceeds 30 minutes, the time increases. Even so, the rate of change in resistance (ΔR / R) is constant. Accordingly, the annealing process time is preferably 30 minutes.

  As shown in FIGS. 7A and 7B, when an aluminum film having a film thickness of 1.0 nm is used as the barrier layers 71 to 74, an annealing process is not performed (see FIG. 7A). , And the annealing step (temperature = 385 ° C., time = about 30 minutes) (see FIG. 7B), no problematic hysteresis occurs.

  On the other hand, as shown in FIGS. 8A and 8B, there is a problem when the barrier layers 71 to 74 are not provided and when the annealing process is not performed (see FIG. 8A). Hysteresis does not occur, but hysteresis occurs when the annealing process (temperature = 385 ° C., time = about 30 minutes) is performed (see FIG. 8B).

  Therefore, when an aluminum film having a film thickness of 1.0 nm is used as the barrier layers 71 to 74, the resistance change rate (ΔR / R) is improved even when the annealing process is not performed, and the resistance is improved by performing the annealing process. Even when the rate of change (ΔR / R) is further improved, no problematic hysteresis occurs.

  As shown in FIG. 9, even when a titanium film having a film thickness of 1.0 nm is used as the barrier layers 71 to 74 and an annealing process (temperature = 385 ° C., time = about 30 minutes) is performed, the resistance change rate ( ΔR / R) is large, and no problematic hysteresis occurs.

(Main effects of this form)
As described above, in this embodiment, after the magnetoresistive film 49 is formed, the barrier layer 79 is laminated on the surface of the magnetoresistive film 49 without bringing the magnetoresistive film 49 into contact with the oxidizing atmosphere. The resistance film 49 and the barrier layer 79 are patterned. For this reason, it is possible to prevent the surface of the magnetoresistive film 49 (the magnetoresistive films 41 to 44) from being oxidized, and the resistance change rate can be improved. Moreover, since the film thickness of the barrier layers 71-74 is thinner than the film thickness of the magnetoresistive films 41-44, the barrier layers 71-74 can be applied without imposing large restrictions on the nonmagnetic material used for the barrier layers 71-74. The resistance of is great. For this reason, even when the barrier layers 71 to 74 are laminated on the magnetoresistive films 41 to 44, an adverse effect on the rate of change in resistance can be prevented and the advantage resulting from the prevention of oxidation can be utilized. Therefore, the magnetoresistive element 4 having a high resistance change rate can be obtained.

  In addition, when the barrier layers 71 to 74 are provided, the occurrence of a problematic hysteresis can be suppressed even when the resistance change rate is improved using an annealing process.

  Further, when the thickness of the barrier layers 71 to 74 is set to 0.5 nm to 2.0 nm, the resistance of the barrier layers 71 to 74 is large regardless of the type of the nonmagnetic material used for the barrier layers 71 to 74. For this reason, even when the barrier layers 71 to 74 are laminated on the magnetoresistive films 41 to 44, an adverse effect on the rate of change in resistance can be prevented and the advantage resulting from the prevention of oxidation can be utilized. In particular, when the thickness of the barrier layers 71 to 74 is 1.0 nm, the effect is remarkable.

  Moreover, it is preferable that the barrier layers 71-74 have aluminum or titanium as a main component. According to this configuration, the barrier layers 71 to 74 can be formed of a relatively inexpensive nonmagnetic metal. In particular, when the barrier layers 71 to 74 are aluminum, the sputtering target is inexpensive, so that the barrier layers 71 to 74 can be formed of a relatively inexpensive nonmagnetic metal.

  Further, in the case where the functional layer made of the same metal material as the barrier layers 71 to 74 is formed on the substrate 40, the metal material to be formed on the substrate 40 even if the barrier layers 71 to 74 are added. Kind does not change. Therefore, the barrier layers 71 to 74 can be formed using the vapor deposition material used for forming the functional layer. That is, when the temperature monitoring resistance film 47 and the heating resistance film 48 formed as a functional layer on the substrate 40 and the barrier layers 71 to 74 are made of the same metal material, even if the barrier layers 71 to 74 are added, Since it is not necessary to prepare a new vapor deposition material, an increase in cost can be suppressed.

  In this embodiment, the annealing process is performed after the etching mask removing process. For this reason, the barrier layers 71 to 74 are formed on the magnetoresistive films 41 to 44, and the annealing process is performed after the magnetoresistive film 49 and the barrier layer 79 are patterned. Can be reduced. Therefore, the effect of the annealing process is great.

  In the magnetic sensor device 10 of this embodiment, the temperature monitoring resistance film 47 and the heating resistance film 48 are formed on the substrate 40 on which the magnetoresistive films 41 to 44 are formed. For this reason, the temperature difference or temperature change from the set temperature is monitored by the resistance value of the temperature monitoring resistance film 47, and the heating resistance film 48 is supplied based on the monitoring result, and the magnetoresistive films 41 to 44 are set to the set temperature. Can be heated up to Therefore, in each of the magnetoresistive films 41 to 44, even when the resistance change rate due to the influence of stress when the temperature change occurs and the resistance change rate due to the difference in film quality are different, the set temperature is high. If the resistance balance of the magnetoresistive films 41 to 44 is set so as to obtain accuracy, stable detection accuracy can be obtained even if the environmental temperature changes. That is, even if a temperature change occurs, the origin position of the Lissajous diagram shown in FIG. 1C does not move, so that the rotational angle position of the rotating body 2 can be detected with high accuracy.

1 .. Rotary encoder 2 .. Rotating body 4 .. Magnetoresistive element 40 .. Substrate 41 to 44, 49 .. Magnetoresistive film 47 .. Resistance film for monitoring temperature (functional layer)
48 .. Resistance film for heating (functional layer)
71-74, 79 ... Barrier layer

Claims (10)

A substrate,
A magnetoresistive film formed on one side of the substrate;
A barrier layer made of a nonmagnetic metal film that is laminated on the surface of the magnetoresistive film opposite to the substrate with the same pattern as the magnetoresistive film, and is thinner than the magnetoresistive film;
Have
The barrier layer is composed of aluminum as a main component .   The magnetoresistive element according to claim 1, wherein the barrier layer has a thickness of 0.5 nm to 2.0 nm.   The magnetoresistive element according to claim 2, wherein the barrier layer has a thickness of 1.0 nm. The magnetoresistive element according to any one of claims 1 to 3 , wherein a functional layer made of the same metal material as the barrier layer is formed on the substrate. The magnetoresistive element according to claim 1, wherein the magnetoresistive film has a thickness of 10 nm to 80 nm . A magnetic sensor device comprising the magnetoresistive element according to claim 1. A magnetoresistive film forming step of forming a magnetoresistive film on one side of the substrate;
A barrier layer forming step of forming a barrier layer made of a nonmagnetic metal film having a thickness smaller than that of the magnetoresistive film on the surface of the magnetoresistive film without contacting the magnetoresistive film with an oxidizing atmosphere;
A mask forming step of forming an etching mask on the surface of the barrier layer;
An etching step of etching the magnetoresistive film and the barrier layer in a state where the etching mask is formed on the surface of the barrier layer;
An etching mask removing step for removing the etching mask;
Have
The method for manufacturing a magnetoresistive element, wherein the barrier layer contains aluminum as a main component. 8. The barrier layer forming step is performed in the vacuum chamber without introducing an oxidizing gas into the vacuum chamber after the magnetoresistive film forming step is performed in the vacuum chamber. Of manufacturing the magnetoresistive element. After performing the magnetoresistive film forming step,
The magnetism according to claim 7 or 8, wherein an annealing step is performed in which the magnetoresistive film is heated at a temperature higher than a film forming temperature of the magnetoresistive film in the magnetoresistive film forming step in a non-oxidizing atmosphere. A method of manufacturing a resistance element. The method of manufacturing a magnetoresistive element according to claim 7, wherein the annealing step is performed after the etching mask removing step .

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