Magnetic sensor and method of manufacturing the same

Abstract

The application discloses a magnetic sensor, which comprises a chip provided with a bottom electrode and a device group arranged on the chip, wherein the device group comprises a first magnetic tunnel junction device electrically connected with the bottom electrode; a wire layer arranged above the first magnetic tunnel junction device; a second magnetic tunnel junction device and a second mask layer arranged on the upper surface of the wire layer in sequence, the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and opposite; a top electrode arranged on the upper surface of the second mask layer; and a signal leading-out part connected with the wire layer. The first magnetic tunnel junction device and the second magnetic tunnel junction device are distributed in the vertical direction, the area of the magnetic sensor can be reduced, and the magnetic moment directions of the reference layers in the two magnetic tunnel junction devices are parallel and opposite, so that the resistance changes of the two devices under the action of the same magnetic field are opposite, that is, the Wheatstone half-bridge can be formed by forming the first magnetic tunnel junction device and the second magnetic tunnel junction device on the same chip, and no special process is needed, which is very simple.

Description

Technical Field

[0001] This application relates to the field of magnetic sensor technology, and in particular to a magnetic sensor and a method for manufacturing the same. Background Technology

[0002] Currently, magnetic sensors are basically fabricated using the tunneling magnetoresistance (TMR) effect of magnetic tunneling junctions (MTJs) and configured as Wheatstone bridges (full bridges or half bridges) to improve the sensitivity of the sensed magnetic field.

[0003] Existing magnetic sensors require the fabrication of MTJ devices with specific resistance-magnetic field variation modes, followed by the series connection of multiple identical MTJ devices to form a single arm of a Wheatstone bridge. Since the Wheatstone bridge operates under conditions requiring opposite output signals from different arms to the external magnetic field, achieving a full-bridge or half-bridge configuration necessitates simultaneously obtaining MTJ devices with opposite resistance-magnetic field variation modes and integrating them to form different arms of the Wheatstone bridge.

[0004] Currently, a single process flow can only fabricate MTJ devices with the same output signal change trend. To obtain MTJ devices with opposite resistance-magnetic field change modes, there are two approaches. One is to design two MTJ growth processes to deposit MTJ devices at different locations on the chip, resulting in MTJ devices with opposite characteristics. This results in a larger area for the magnetic sensor and more complex process steps. The other approach is to use only one MTJ growth process to grow identical MTJ devices. Then, the MTJ devices in different areas of the chip are magnetized or annealed in magnetic fields in opposite directions to obtain MTJ devices with opposite characteristics. This results in a larger area for the magnetic sensor and makes it difficult to precisely control the magnetic field range.

[0005] Therefore, how to solve the above-mentioned technical problems should be a key focus for those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to provide a magnetic sensor and a method for manufacturing the same, so as to reduce the area of ​​the magnetic sensor and simplify the process flow.

[0007] To address the aforementioned technical problems, this application provides a magnetic sensor, comprising a chip with a bottom electrode and a device group disposed on the chip, the device group comprising:

[0008] A first magnetic tunnel junction device electrically connected to the bottom electrode;

[0009] A conductor layer located above the first magnetic tunnel junction device;

[0010] A second magnetic tunnel junction device and a second mask layer are stacked sequentially on the upper surface of the conductor layer, wherein the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and opposite.

[0011] A top electrode is disposed on the upper surface of the second mask layer;

[0012] The signal lead-out section connected to the conductor layer.

[0013] Optionally, the long axis directions of the first magnetic tunnel junction device and the second magnetic tunnel junction device are the same.

[0014] Optionally, the first magnetic tunnel junction device and the second magnetic tunnel junction device are elliptical cylinders.

[0015] Optional, also includes:

[0016] A first mask layer is disposed on the upper surface of the first magnetic tunnel junction device;

[0017] A first insulating layer is disposed around the first magnetic tunnel junction device and flush with the first mask layer.

[0018] Optional, also includes:

[0019] A second insulating layer is disposed around the second magnetic tunnel junction device and flush with the second mask layer; the signal lead-out portion penetrates the second insulating layer.

[0020] Optionally, when there are multiple device groups, the multiple device groups form a Wheatstone half-bridge, in which a first preset number of first magnetic tunnel junction devices are connected in series, and a second preset number of second magnetic tunnel junction devices are connected in series, wherein both the first preset number and the second preset number are less than the number of device groups.

[0021] Optionally, when there are multiple device groups, the multiple device groups form a Wheatstone full bridge. The Wheatstone full bridge includes a first half bridge and a second half bridge connected in parallel. A third preset number of first magnetic tunnel junction devices in the first half bridge and the second half bridge are connected in series, and a fourth preset number of second magnetic tunnel junction devices are connected in series.

[0022] This application also provides a method for manufacturing a magnetic sensor, including:

[0023] A bottom electrode is formed on the chip;

[0024] A first magnetic tunnel junction device electrically connected to the bottom electrode is fabricated on the upper surface of the bottom electrode;

[0025] A conductive layer is formed above the first magnetic tunnel junction device;

[0026] A second magnetic tunnel junction device and a second mask layer are sequentially stacked on the upper surface of the conductor layer;

[0027] A top electrode is formed on the upper surface of the second mask layer;

[0028] Prepare a signal lead-out section connected to the conductor layer;

[0029] The first magnetic tunnel junction device and the second magnetic tunnel junction device are magnetized using a first magnetic field so that the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and the same.

[0030] The first magnetic tunnel junction device or the second magnetic tunnel junction device is magnetized by using a second magnetic field that is opposite in direction and of different magnitude to the first magnetic field, so that the magnetic moment direction of the reference layer of the device magnetized by the second magnetic field is parallel and opposite to the magnetic moment direction of the reference layer of the device not magnetized by the second magnetic field, thereby obtaining a magnetic sensor.

[0031] Optionally, fabricating a first magnetic tunnel junction device electrically connected to the bottom electrode on the upper surface of the bottom electrode includes:

[0032] A first magnetic tunnel junction device to be processed is fabricated on the upper surface of the bottom electrode, and a first mask layer is formed on the upper surface of the first magnetic tunnel junction device to be processed;

[0033] Using the first mask layer as a mask, the first magnetic tunnel junction device to be processed is etched to form the first magnetic tunnel junction device.

[0034] Optionally, during the etching process to form the conductive layer, the etching stops at the upper surface of the conductive layer.

[0035] This application provides a magnetic sensor comprising a chip with a bottom electrode and a device assembly disposed on the chip. The device assembly includes: a first magnetic tunnel junction device electrically connected to the bottom electrode; a conductive layer disposed above the first magnetic tunnel junction device; a second magnetic tunnel junction device and a second mask layer disposed on the upper surface of the conductive layer and stacked sequentially, wherein the magnetic moment directions of the reference layers in the first and second magnetic tunnel junction devices are parallel and opposite; a top electrode disposed on the upper surface of the second mask layer; and a signal lead-out portion connected to the conductive layer.

[0036] As can be seen, the device group in the magnetic sensor of this application is directly disposed on the chip. The first magnetic tunnel junction device and the second magnetic tunnel junction device in the device group are distributed in the vertical direction, which can reduce the area of ​​the magnetic sensor. The magnetic moment directions of the reference layer in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and opposite, so that the resistance of the first magnetic tunnel junction device and the second magnetic tunnel junction device changes in opposite directions under the same magnetic field. That is, by forming the first magnetic tunnel junction device and the second magnetic tunnel junction device on the same chip, a Wheatstone half-bridge can be formed without special equipment or processes, which is very simple.

[0037] In addition, this application also provides a method for manufacturing a magnetic sensor with the above advantages. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a magnetic sensor provided in an embodiment of this application;

[0040] Figure 2 This is a schematic diagram illustrating the relationship between the chip and the z-axis in an embodiment of this application;

[0041] Figure 3 This is a schematic diagram showing the resistance change of the first magnetic tunnel junction device and the second magnetic tunnel junction device under the action of a magnetic field in the embodiments of this application.

[0042] Figure 4 This is a schematic diagram showing the resistance change of the first magnetic tunnel junction device and the second magnetic tunnel junction device under the action of another magnetic field in the embodiments of this application.

[0043] Figure 5 This is a schematic diagram of the structure of a Wheatstone half-bridge in a magnetic sensor provided in an embodiment of this application;

[0044] Figure 6 A flowchart illustrating a method for manufacturing a magnetic sensor provided in an embodiment of this application;

[0045] Figures 7 to 21 This is a flowchart illustrating the manufacturing process of a magnetic sensor, as provided in an embodiment of this application.

[0046] Figure 22 A schematic diagram showing two Wheatstone half-bridges connected in parallel to form a Wheatstone full bridge. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0049] As described in the background section, current magnetic sensors are fabricated by preparing two MTJ devices with different resistance characteristics on two separate chips and then packaging them together to obtain MTJ devices with opposite resistance-magnetic field change modes. This results in a large area of ​​the magnetic sensor. When fabricating MTJ devices with different resistance characteristics on the same chip, two MTJ growth processes need to be designed to obtain MTJ devices with opposite characteristics, which involves many and complex process steps. Alternatively, the same MTJ devices can be grown in different areas of the chip using a single MTJ growth process, and then processed to form MTJ devices with opposite characteristics. This also results in a large area of ​​the magnetic sensor and makes it difficult to accurately control the magnetic field range.

[0050] In view of this, this application provides a magnetic sensor, please refer to... Figure 1 The device includes a chip with a bottom electrode 1 and a device assembly disposed on the chip, the device assembly comprising:

[0051] The first magnetic tunnel junction device 2 is electrically connected to the bottom electrode 1;

[0052] A conductor layer 5 is disposed above the first magnetic tunnel junction device 2;

[0053] A second magnetic tunnel junction device 6 and a second mask layer 7 are stacked sequentially on the upper surface of the conductor layer 5. The magnetic moment directions of the reference layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are parallel and opposite.

[0054] Top electrode 9 is disposed on the upper surface of the second mask layer 7;

[0055] Signal lead-out section 10 connected to the conductor layer.

[0056] Optionally, the magnetic sensor may also include:

[0057] A first mask layer 3 is disposed on the upper surface of the first magnetic tunnel junction device 2;

[0058] A first insulating layer 4 is disposed around the first magnetic tunnel junction device 2 and flush with the first mask layer 3. Correspondingly, a conductor layer 5 is located on the upper surface of the first mask layer 3 and the first insulating layer 4.

[0059] A second insulating layer 8 is disposed around the second magnetic tunnel junction device 6 and flush with the second mask layer 7; the signal lead-out portion 10 penetrates the second insulating layer 8.

[0060] The first insulating layer 4 includes:

[0061] A first insulating unit layer 41 is disposed around the first magnetic tunnel junction device 2;

[0062] A second insulating unit layer 42 is disposed on the outer surface of the first insulating unit layer.

[0063] The material of the first insulating unit layer can be silicon nitride, and the material of the second insulating unit layer can be silicon dioxide or silicon oxynitride, etc., as an oxide insulating layer.

[0064] The second insulating layer 8 includes:

[0065] A third insulating unit layer 81 is disposed around the second magnetic tunnel junction device 6;

[0066] A fourth insulating unit layer 82 is disposed on the outer surface of the third insulating unit layer.

[0067] The material of the third insulating unit layer can be silicon nitride, and the fourth insulating unit layer can be an oxide insulating layer such as silicon dioxide or silicon oxynitride.

[0068] The first mask layer 3 and the second mask layer 7 are conductive film layers, and the materials can be any one of tantalum, tantalum nitride, titanium nitride, etc.

[0069] The first magnetic tunnel junction device 2 includes a seed layer 21, a first pinning layer 22, a first coupling layer 23, a first reference layer 24, a first barrier layer 25, a first free layer 26, and a first capping layer 27 stacked from bottom to top. The second magnetic tunnel junction device 6 includes a second free layer 61, a second barrier layer 62, a second reference layer 63, a second coupling layer 64, a second pinning layer 65, and a second capping layer 66 stacked from bottom to top.

[0070] The seed layer 21 can be made of materials including but not limited to ruthenium, platinum, and nickel-chromium alloys; the first pinning layer 22 and the second pinning layer 65 can be cobalt-iron-boron alloys, cobalt, cobalt / platinum multilayer films, cobalt / nickel multilayer films, etc. of different compositions. When it is a multilayer film structure, the number of repetitions in the first pinning layer 22 and the second pinning layer 65 can be different or the same; the first coupling layer 23 and the second coupling layer 64 can be made of materials including but not limited to ruthenium, iridium, and rhodium; the first barrier layer 25 and the second barrier layer 62 can be made of materials such as magnesium oxide, aluminum oxide, and gallium magnesium oxide; the first reference layer 24 and the second reference layer 63 can be made of cobalt-iron-boron alloys of different compositions; the first free layer 26 and the first free layer 61 can be made of cobalt-iron-boron alloys of different compositions and related materials. The thickness of the first free layer 26 and the second free layer 61 is between 1.5 nanometers and 3 nanometers; the first capping layer 27 and the second capping layer 66 can be made of materials such as magnesium oxide, tantalum, tungsten, molybdenum, cobalt-iron-boron alloys of different compositions, ruthenium, tantalum, ruthenium / tantalum multilayer films, etc. The thickness of the first barrier layer 25 and the second barrier layer 62 is determined by the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 and the required resistance of a single arm of the Wheatstone bridge. Generally, the thickness of the first barrier layer 25 and the second barrier layer 62 is between 1 nanometer and 3 nanometers.

[0071] The first free layer 26 and the second free layer 61 have in-plane magnetic anisotropy. The first coupling layer 23, the second coupling layer 64, the first barrier layer 25, the second barrier layer 62, the seed layer 21, the first capping layer 27 and the second capping layer 66 are non-magnetic. The first pinning layer 22, the second pinning layer 65, the first reference layer 24 and the second reference layer 63 have out-of-plane magnetic anisotropy.

[0072] The magnetic moments of the reference layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are parallel and opposite, that is, the magnetic moments of the first reference layer 24 and the second reference layer 63 are parallel and opposite, thus causing the resistance changes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 to be opposite under the same magnetic field. The magnetic moments of the first pinning layer 22 and the second pinning layer 65 are opposite, which can be achieved by applying magnetic fields of different magnitudes and opposite directions but perpendicular to the chip plane. Due to the interlayer coupling, the magnetic moments of the first reference layer 24 and the second reference layer 63 are opposite to those of the first pinning layer 22 and the second pinning layer 65, respectively, so the magnetic moments of the first reference layer 24 and the second reference layer 63 are also opposite.

[0073] When the first reference layer 24 and the second reference layer 63 are flipped under a magnetic field perpendicular to the chip surface, the resistance of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 changes in the opposite mode to the magnetic field, thereby realizing a Wheatstone half bridge.

[0074] Please refer to Figure 2 and Figure 3The z-axis is perpendicular to the chip surface. When the magnetic field direction is -z, the magnetic moment directions of the magnetic layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are as follows: Figure 3 As shown in the diagram, at this point, the free layer magnetic moment of the first magnetic tunnel junction is parallel to the magnetic moment of the first reference layer 24, exhibiting a low resistance value, while the free layer magnetic moment of the second magnetic tunnel junction is antiparallel to the magnetic moment of the second reference layer 63, exhibiting both high and low resistance values. When the magnetic field direction changes to +z, the free layer magnetic moment of the first magnetic tunnel junction is antiparallel to the magnetic moment of the first reference layer 24, exhibiting a high resistance value, while the free layer magnetic moment of the second magnetic tunnel junction is parallel to the magnetic moment of the second reference layer 63, exhibiting a low resistance value. This achieves two opposite resistance-magnetic field response modes within the same structure, thus realizing a half-bridge structure of a Wheatstone bridge in situ. At this point, the magnetic sensor can sense the magnetic field in the z-direction, i.e., perpendicular to the upper surface of the chip.

[0075] Please refer to Figure 4 When the magnetic field direction is perpendicular to the z-axis, for example, parallel to the x-axis or y-axis, the magnetic moment directions of the magnetic layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are as follows: Figure 4 As shown, when the free layer magnetic moment of the first magnetic tunnel junction is parallel to the magnetic moment of the first reference layer 24, it exhibits a low resistance value; the free layer magnetic moment of the second magnetic tunnel junction is antiparallel to the magnetic moment of the second reference layer 63, exhibiting both high and low resistance values. When the magnetic field direction is rotated 180°, the free layer magnetic moment of the first magnetic tunnel junction is antiparallel to the magnetic moment of the first reference layer 24, exhibiting a high resistance value; the free layer magnetic moment of the second magnetic tunnel junction is parallel to the magnetic moment of the second reference layer 63, exhibiting a low resistance value. At this time, the magnetic sensor can sense the magnetic field in the x and y directions, that is, parallel to the upper surface of the chip.

[0076] The second magnetic tunnel junction device 6 and the first magnetic tunnel junction device 2 may or may not overlap in the direction perpendicular to the chip; this application does not impose any limitation on this. When they overlap, it will not affect the signal extraction.

[0077] It should be noted that the shapes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are not limited in this application and can be set arbitrarily. The major axes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are in the same direction. For example, the shapes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 can be cylindrical or elliptical. When cylindrical, the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 is the diameter; when elliptical, the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 is the major axis or the minor axis. The major axis width of an elliptical cylinder is generally between 1 micrometer and 20 micrometers, and the minor axis width is generally between 0.1 micrometer and 10 micrometers; the diameter of a cylindrical device is generally between 0.1 micrometer and 10 micrometers.

[0078] Furthermore, the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are elliptical cylinders, and their major axes are in the same direction. For example, the major axes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are both parallel to the z-axis, or both are parallel to the x-axis.

[0079] The absolute value of the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 is determined by the resistance value required by the Wheatstone bridge, and the width difference is determined by the width (diameter) of the signal lead-out section 10.

[0080] The conductor layer 5 is a metal conductor layer, and the thickness of the conductor layer 5 can be between 1 nanometer and 100 nanometers. The material of the metal conductor layer is any one or any combination of cobalt, tungsten, ruthenium, molybdenum and tantalum.

[0081] The bottom electrode 1 can be made of tantalum nitride or titanium nitride, etc., and the top electrode 9 can also be made of tantalum nitride, titanium nitride, etc.

[0082] In this application, the device group of the magnetic sensor is directly mounted on the chip. The first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 in the device group are distributed in the vertical direction, which can reduce the area of ​​the magnetic sensor. A conductor layer 5 is provided between the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6. The signal lead-out part 10 is connected to the conductor layer 5. The magnetic moment directions of the reference layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 are parallel and opposite, so that the resistance of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 changes in opposite directions under the same magnetic field. That is, by forming the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 6 on the same chip and setting the first mask layer 3, the first insulating layer 4, the second mask layer 7 and the second insulating layer 8, a Wheatstone half-bridge can be formed without special equipment or processes, which is very simple.

[0083] Based on the above embodiments, in one embodiment of this application, when the number of device groups is multiple, the multiple device groups form a Wheatstone half-bridge, in which a first preset number of first magnetic tunnel junction devices 2 are connected in series, and a second preset number of second magnetic tunnel junction devices 6 are connected in series, the first preset number and the second preset number are both less than the number of device groups.

[0084] This application does not limit the first preset quantity and the second preset quantity; they can be set by the user.

[0085] Multiple first magnetic tunnel junction devices 2 and multiple second magnetic tunnel junction devices 6 can be connected in series through preset metal wiring. Taking a group of 5 devices as an example, the resulting Wheatstone half-bridge is as follows: Figure 5As shown, from left to right, the first magnetic tunnel junction device 2 in the three device groups on the left is connected in series, and from right to left, the second magnetic tunnel junction device 6 in the three device groups on the right is connected in series. The signal is output from the signal lead-out section 10 in the middle device group.

[0086] Based on the above embodiments, in one embodiment of this application, when the number of device groups is multiple, the multiple device groups form a Wheatstone full bridge. The Wheatstone full bridge includes a first half bridge and a second half bridge connected in parallel. A third preset number of first magnetic tunnel junction devices 2 in the first half bridge and the second half bridge are connected in series, and a fourth preset number of second magnetic tunnel junction devices 6 are connected in series.

[0087] This application does not limit the number of the third and fourth preset quantities; these can be set by the user.

[0088] The structural diagrams of the first and second half-bridges can be referenced. Figure 4 It should be noted that when the first and second half-bridges are connected in parallel, the first and second half-bridges are connected in parallel by connecting their ends, as shown below. Figure 22 As shown.

[0089] This application also provides a method for manufacturing a magnetic sensor; please refer to [reference needed]. Figure 6 The method includes:

[0090] Step S101: Form the bottom electrode on the chip.

[0091] Step S102: Prepare a first magnetic tunnel junction device that is electrically connected to the bottom electrode on the upper surface of the bottom electrode.

[0092] Optionally, this step includes:

[0093] Step S1021: Prepare the first magnetic tunnel junction device to be processed on the upper surface of the bottom electrode, and form a first mask layer on the upper surface of the first magnetic tunnel junction device to be processed;

[0094] Please refer to the following steps. Figure 7 First, a first magnetic tunnel junction device 2' to be processed is prepared. Then, a first mask layer to be processed is prepared on the upper surface. The first mask layer to be processed is then photolithographically etched and etched to obtain the first mask layer 3.

[0095] The first magnetic tunnel junction device 2' to be processed includes a seed layer, a first pinning layer, a first coupling layer, a first reference layer, a first barrier layer, a first free layer, and a first capping layer stacked sequentially from bottom to top.

[0096] Step S1022: Using the first mask layer as a mask, etch the first magnetic tunnel junction device to be processed to form the first magnetic tunnel junction device.

[0097] Optionally, etching the first magnetic tunnel junction device to be processed to form the first magnetic tunnel junction device includes:

[0098] Dry etching is used to etch the first magnetic tunnel junction device to be processed, forming the first magnetic tunnel junction device. The dry etching can be ion beam etching or reactive ion etching. Wet etching can also be used to etch the first magnetic tunnel junction device to be processed; this application does not specify a particular method. In this step, during etching, the etching stops at the interface where the bottom electrode is located, or extends 1 nanometer to 10 nanometers beyond the interface.

[0099] Please refer to the schematic diagram after the formation of the first magnetic tunnel junction device 2. Figure 8 .

[0100] Optionally, after the first magnetic tunnel junction device, the method further includes: forming a first insulating layer around the first magnetic tunnel junction device, the first insulating layer being flush with the upper surface of the first mask layer, specifically including:

[0101] Step S201: Form a first insulating unit layer 41 around the first magnetic tunnel junction device, such as Figure 9 As shown;

[0102] Step S202: Form a second insulating unit layer 42 on the outer surface of the first insulating unit layer 41, such as... Figure 10 As shown;

[0103] Step S203: Use chemical mechanical planarization to grind the upper surfaces of the first and second insulating unit layers until the first mask layer is exposed, as shown below. Figure 11 As shown.

[0104] Step S103: Form a conductive layer above the first magnetic tunnel junction device.

[0105] Step S104: Prepare a second magnetic tunnel junction device and a second mask layer that are stacked sequentially on the upper surface of the conductor layer.

[0106] Please refer to the following steps. Figures 12 to 14 A conductor layer 5' to be processed is formed on the upper surface of the first mask layer and the first insulating layer. A second magnetic tunnel junction device to be processed is fabricated on the upper surface of the conductor layer 5'. Optionally, a second mask layer to be processed is fabricated on the upper surface of the second magnetic tunnel junction device to be processed, and the second mask layer to be processed is photolithographically etched and etched to obtain a second mask layer 7. The second mask layer 7 is used as a mask to etch the second magnetic tunnel junction device to be processed to form the second magnetic tunnel junction device.

[0107] The second magnetic tunnel junction device to be processed includes, from bottom to top, a second free layer, a second barrier layer, a second reference layer, a second coupling layer, a second pinning layer, and a second capping layer.

[0108] The etching of the second magnetic tunnel junction device to be processed can be done by ion beam etching or reactive ion etching.

[0109] Optionally, after forming the second magnetic tunnel junction device, it also includes:

[0110] A third insulating unit layer 81 is formed around the second magnetic tunnel junction device, such as Figure 15 As shown;

[0111] A fourth insulating unit layer 82 is formed on the outer surface of the third insulating unit layer 81, such as Figure 16 As shown;

[0112] The upper surfaces of the third insulating unit layer 81 and the fourth insulating unit layer 82 are ground smooth using a chemical mechanical planarization method until the second mask layer is exposed, forming a pretreated second insulating layer, such as... Figure 17 As shown;

[0113] A third mask layer to be processed is formed on the upper surface of the second mask layer and the pre-treated second insulating layer, and the third mask layer 11 is formed by photolithography and etching according to the metal wiring pattern, such as... Figure 18 As shown, the pre-treated second insulating layer and the conductor layer to be treated are then etched to form the second insulating layer and conductor layer 5, as shown. Figure 19 As shown.

[0114] Optionally, when etching the pre-treatment second insulating layer and the conductive layer to be treated, the etching stops at the upper surface of the conductive layer to be treated, that is, at the interface between the conductive layer to be treated and the second insulating layer. However, this application does not specifically limit this. As another embodiment, when etching the pre-treatment second insulating layer and the conductive layer to be treated, the etching extends beyond the interface between the conductive layer to be treated and the second insulating layer, and the etching depth of the conductive layer to be treated is between 1 nanometer and 30 nanometers.

[0115] Step S105: Form a top electrode on the upper surface of the second mask layer.

[0116] Please refer to Figure 20 and Figure 21 First, an interlayer oxide insulating layer 12 is formed on the third mask layer. Then, a chemical mechanical planarization method is used to grind it until the second mask layer 7 is exposed, and a top electrode is formed on the second mask layer 7.

[0117] Step S106: Prepare a signal lead-out section connected to the conductor layer.

[0118] Through-holes can be fabricated using the damascus process, followed by depositing metal within the through-hole to form signal leads, resulting in... Figure 1 The schematic diagram shown indicates that the signal lead-out section is electrically connected to the conductor layer.

[0119] Step S107: Magnetize the first magnetic tunnel junction device and the second magnetic tunnel junction device using a first magnetic field, so that the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and the same.

[0120] Step S108: Use a second magnetic field with the opposite direction and different magnitude to the first magnetic field to magnetize the first magnetic tunnel junction device or the second magnetic tunnel junction device, so that the magnetic moment direction of the reference layer of the device magnetized by the second magnetic field is parallel and opposite to the magnetic moment direction of the reference layer of the device not magnetized by the second magnetic field, to obtain a magnetic sensor.

[0121] In the prior art, MTJ devices in different regions of a chip are magnetized or annealed in magnetic fields in opposite directions to obtain MTJ devices with opposite characteristics. However, the range of the magnetic field is difficult to control precisely. In this application, two magnetic fields with opposite directions and different magnitudes are used to magnetize all devices on the chip in two separate processes to obtain a first magnetic tunnel junction device and a second magnetic tunnel junction device with opposite characteristics. This is very simple and convenient, and can also reduce the area of ​​the magnetic sensor.

[0122] The above embodiments are illustrated using a single device group as an example. When there are multiple devices, multiple device groups can be configured to form Wheatstone half-bridge and full-bridge structures by setting up wiring.

[0123] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0124] The magnetic sensor and its manufacturing method provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A magnetic sensor, characterized in that, It includes a chip with a bottom electrode and a device group disposed on the chip, the device group including: A first magnetic tunnel junction device electrically connected to the bottom electrode; A conductor layer located above the first magnetic tunnel junction device; A second magnetic tunnel junction device and a second mask layer are stacked sequentially on the upper surface of the conductor layer, wherein the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and opposite. A top electrode is disposed on the upper surface of the second mask layer; The signal lead-out section is connected to the conductor layer; When there are multiple device groups, the multiple device groups form a Wheatstone half-bridge. In the Wheatstone half-bridge, a first preset number of first magnetic tunnel junction devices are connected in series, and a second preset number of second magnetic tunnel junction devices are connected in series. Both the first preset number and the second preset number are less than the number of device groups. When there are multiple device groups, the multiple device groups form a Wheatstone full bridge. The Wheatstone full bridge includes a first half bridge and a second half bridge connected in parallel. A third preset number of first magnetic tunnel junction devices are connected in series in the first half bridge and the second half bridge, and a fourth preset number of second magnetic tunnel junction devices are connected in series.

2. The magnetic sensor as described in claim 1, characterized in that, The long axis directions of the first magnetic tunnel junction device and the second magnetic tunnel junction device are the same.

3. The magnetic sensor as described in claim 2, characterized in that, The first magnetic tunnel junction device and the second magnetic tunnel junction device are elliptical cylinders.

4. The magnetic sensor as described in claim 1, characterized in that, Also includes: A first mask layer is disposed on the upper surface of the first magnetic tunnel junction device; A first insulating layer is disposed around the first magnetic tunnel junction device and flush with the first mask layer.

5. The magnetic sensor as described in claim 1, characterized in that, Also includes: A second insulating layer is disposed around the second magnetic tunnel junction device and flush with the second mask layer; the signal lead-out portion penetrates the second insulating layer.

6. A method for manufacturing a magnetic sensor, characterized in that, include: A bottom electrode is formed on the chip; A first magnetic tunnel junction device electrically connected to the bottom electrode is fabricated on the upper surface of the bottom electrode; A conductive layer is formed above the first magnetic tunnel junction device; A second magnetic tunnel junction device and a second mask layer are sequentially stacked on the upper surface of the conductor layer; A top electrode is formed on the upper surface of the second mask layer; Prepare a signal lead-out section connected to the conductor layer; The first magnetic tunnel junction device and the second magnetic tunnel junction device are magnetized using a first magnetic field so that the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device are parallel and the same. The first magnetic tunnel junction device or the second magnetic tunnel junction device is magnetized by using a second magnetic field that is opposite in direction and of different magnitude to the first magnetic field, so that the magnetic moment direction of the reference layer of the device magnetized by the second magnetic field is parallel and opposite to the magnetic moment direction of the reference layer of the device not magnetized by the second magnetic field, thereby obtaining a magnetic sensor.

7. The method for manufacturing a magnetic sensor as described in claim 6, characterized in that, Fabricating a first magnetic tunnel junction device electrically connected to the bottom electrode on the upper surface of the bottom electrode includes: A first magnetic tunnel junction device to be processed is fabricated on the upper surface of the bottom electrode, and a first mask layer is formed on the upper surface of the first magnetic tunnel junction device to be processed; Using the first mask layer as a mask, the first magnetic tunnel junction device to be processed is etched to form the first magnetic tunnel junction device.

8. The method for manufacturing a magnetic sensor as described in claim 6 or 7, characterized in that, When etching the conductive layer to be processed to form the conductive layer, the etching stops at the upper surface of the conductive layer to be processed.

Images