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 double magnetic tunnel junction electrically connected with the bottom electrode, the double magnetic tunnel junction comprises a first magnetic tunnel junction device and a second magnetic tunnel junction device stacked from bottom to top, the width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device, and 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 above the second magnetic tunnel junction device; and a signal lead-out part connected with a free layer in the double magnetic tunnel junction. The application can directly form a Wheatstone half-bridge on the chip, does not need to perform packaging of multiple chips, can reduce the area of the magnetic sensor, and simplifies the process flow. In addition, the application further provides a magnetic sensor manufacturing method with the above advantages.

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 initial fabrication of Mediatized Junction (MTJ) devices with specific resistance-magnetic field variation patterns. Multiple identical MTJ devices are then connected in series to form a single arm of a Wheatstone bridge. Since the Wheatstone bridge operates under conditions requiring opposite output signal trends in different arms to the external magnetic field, achieving a full-bridge or half-bridge configuration necessitates simultaneously obtaining and integrating MTJ devices with opposite resistance-magnetic field variation patterns to form different arms of the Wheatstone bridge. However, current processes can only fabricate MTJ devices with identical output signal variation trends in a single step. This necessitates subsequent packaging of two chips and using special wiring to form a Wheatstone half-bridge or full-bridge, resulting in a large magnetic sensor area. When placing MTJ devices with opposite output signal trends on a single chip, 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 approach involves more process steps and is more complex. The other approach is to grow identical MTJ devices using only one MTJ growth process, magnetizing and annealing MTJ devices in different areas of the chip in magnetic fields in opposite directions to obtain MTJ devices with opposite characteristics. This approach results in a larger area for the magnetic sensor and makes it difficult to precisely control the magnetic field range.

[0004] Therefore, how to solve the above-mentioned technical problems should be a key focus for those skilled in the art. Summary of the Invention

[0005] 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 manufacturing process.

[0006] To address the aforementioned technical problems, this application provides a magnetic sensor, including a chip with a bottom electrode and a device group disposed on the chip, the device group comprising:

[0007] A dual magnetic tunnel junction electrically connected to the bottom electrode, the dual magnetic tunnel junction comprising a first magnetic tunnel junction device and a second magnetic tunnel junction device stacked from bottom to top, wherein the width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device, and 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.

[0008] The top electrode is located above the second magnetic tunnel junction device;

[0009] The signal lead-out section is connected to the free layer in the dual magnetic tunnel junction.

[0010] Optionally, the long axis directions of the first magnetic tunnel junction device and the second magnetic tunnel junction device are the same.

[0011] Optionally, the first magnetic tunnel junction device and the second magnetic tunnel junction device are elliptical cylinders.

[0012] Optionally, it also includes a first mask layer disposed on the upper surface of the second magnetic tunnel junction device.

[0013] Optionally, it also includes a first insulating layer disposed around the second magnetic tunnel junction device and flush with the upper surface of the first mask layer, wherein the signal lead-out portion penetrates the first insulating layer.

[0014] Optional, also includes:

[0015] A second insulating layer is disposed on the side of the first magnetic tunnel junction device and the first insulating layer.

[0016] Optionally, the first insulating layer includes:

[0017] A first insulating unit layer is disposed around the second magnetic tunnel junction device;

[0018] A second insulating unit layer is disposed on the outer surface of the first insulating unit layer.

[0019] Optionally, the material of the first mask layer is any one of tantalum, tantalum nitride, and titanium nitride.

[0020] Optionally, the bottom electrode is made of tantalum nitride or titanium nitride.

[0021] 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.

[0022] 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.

[0023] This application also provides a method for manufacturing a magnetic sensor, including:

[0024] A bottom electrode is formed on the chip;

[0025] A dual magnetic tunnel junction to be processed is fabricated on the upper surface of the bottom electrode. The dual magnetic tunnel junction to be processed includes a first magnetic tunnel junction device to be processed and a second magnetic tunnel junction device to be processed, stacked from bottom to top.

[0026] The first magnetic tunnel junction device and the second magnetic tunnel junction device to be processed are etched to form the first magnetic tunnel junction device and the second magnetic tunnel junction device, wherein the width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device.

[0027] A top electrode is fabricated above the second magnetic tunnel junction device;

[0028] Prepare a signal lead-out section that is connected to the free layer in the dual magnetic tunnel junction;

[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, when etching the second magnetic tunnel junction device to be processed, the etching depth of the free layer is between 1 nanometer and 2 nanometers.

[0032] Optionally, the etching of the first magnetic tunnel junction device to be processed and the second magnetic tunnel junction device to be processed includes:

[0033] The first magnetic tunnel junction device and the second magnetic tunnel junction device to be processed are etched using a dry etching method.

[0034] This application provides a magnetic sensor comprising a chip with a bottom electrode and a device group disposed on the chip. The device group includes: a dual magnetic tunnel junction electrically connected to the bottom electrode, the dual magnetic tunnel junction comprising a first magnetic tunnel junction device and a second magnetic tunnel junction device stacked from bottom to top, the width of the first magnetic tunnel junction device being greater than the width of the second magnetic tunnel junction device, and the magnetic moment directions of the reference layers in the first magnetic tunnel junction device and the second magnetic tunnel junction device being parallel and opposite; a top electrode disposed above the second magnetic tunnel junction device; and a signal lead-out portion connected to the free layer in the dual magnetic tunnel junction.

[0035] As can be seen, in the magnetic sensor of this application, the device group is disposed on the chip. The dual magnetic tunnel junction in the device group includes a first magnetic tunnel junction device and a second magnetic tunnel junction device. The width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device, and the magnetic moment directions of the reference layers in the first and second magnetic tunnel junction devices are parallel and opposite. This makes the resistance changes of the first and second magnetic tunnel junction devices opposite under the same magnetic field. That is, the dual magnetic tunnel junction can be directly formed into a Wheatstone half-bridge on the chip without the need for packaging multiple chips. The chip can be directly used as the chip of the magnetic sensor. Furthermore, the first and second magnetic tunnel junction devices are stacked vertically, reducing the area occupied on the chip and thus reducing the area of ​​the magnetic sensor. The vertical stacking of the first and second magnetic tunnel junction devices avoids setting MTJ devices with different resistance characteristics at different positions on the chip, simplifying the process flow.

[0036] In addition, this application also provides a method for manufacturing a magnetic sensor with the above advantages. Attached Figure Description

[0037] 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.

[0038] Figure 1 This is a schematic diagram of the structure of a magnetic sensor provided in an embodiment of this application;

[0039] Figure 2 This is a schematic diagram illustrating the relationship between the chip and the z-axis in an embodiment of this application;

[0040] Figure 3 This is a schematic diagram showing the resistance change of the first and second magnetic tunnel junction devices under the action of a magnetic field in the embodiments of this application.

[0041] Figure 4This is a schematic diagram of the structure of a Wheatstone half-bridge in a magnetic sensor provided in an embodiment of this application;

[0042] Figure 5 A flowchart illustrating a method for manufacturing a magnetic sensor provided in an embodiment of this application;

[0043] Figures 6 to 16 This is a flowchart illustrating the manufacturing process of a magnetic sensor, as provided in an embodiment of this application.

[0044] Figure 17 A schematic diagram showing two Wheatstone half-bridges connected in parallel to form a Wheatstone full bridge. Detailed Implementation

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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:

[0049] The dual magnetic tunnel junction is electrically connected to the bottom electrode 1. The dual magnetic tunnel junction includes a first magnetic tunnel junction device 2 and a second magnetic tunnel junction device 3 stacked from bottom to top. The width of the first magnetic tunnel junction device 2 is greater than the width of the second magnetic tunnel junction device 3, and the magnetic moment directions of the reference layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 are parallel and opposite.

[0050] The top electrode 7 is located above the second magnetic tunnel junction device 3;

[0051] The signal lead-out section 8 is connected to the free layer 26 in the dual magnetic tunnel junction.

[0052] Optionally, the magnetic sensor may also include a first mask layer 4 disposed on the upper surface of the second magnetic tunnel junction device 3.

[0053] A first insulating layer 5 is disposed around the second magnetic tunnel junction device 3 and flush with the upper surface of the first mask layer 4, and the signal lead-out portion 8 penetrates the first insulating layer 5.

[0054] A second insulating layer 6 is disposed on the side of the first magnetic tunnel junction device 2 and the first insulating layer 5.

[0055] 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, and a free layer 26 stacked sequentially from bottom to top. The second magnetic tunnel junction device 3 includes a free layer 26, a second barrier layer 31, a second reference layer 32, a second coupling layer 33, a second pinning layer 34, and a capping layer 35 stacked sequentially from bottom to top. The first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 share the free layer 26. The first magnetic tunnel junction device 2 is electrically connected to the bottom electrode 1.

[0056] 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 34 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 34 can be different or the same; the first coupling layer 23 and the second coupling layer 33 can be made of materials including but not limited to ruthenium, iridium, and rhodium; the first barrier layer 25 and the second barrier layer 31 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 32 can be made of cobalt-iron-boron alloys of different compositions; the free layer 26 can be made of cobalt-iron-boron alloys of different compositions and related materials, and the thickness of the free layer 26 is between 2 nanometers and 5 nanometers; the capping layer 35 can be made of materials such as magnesium oxide, tantalum, tungsten, molybdenum, cobalt-iron-boron alloys of different compositions, ruthenium, and ruthenium / tantalum multilayer films. The thickness of the first barrier layer 25 and the second barrier layer 31 is determined by the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 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 31 is between 1 nanometer and 3 nanometers.

[0057] The free layer 26 exhibits in-plane magnetic anisotropy. The first coupling layer 23, the second coupling layer 33, the first barrier layer 25, the second barrier layer 31, the seed layer 21, and the capping layer 35 are non-magnetic. The first pinning layer 22, the second pinning layer 34, the first reference layer 24, and the second reference layer 32 exhibit out-of-plane magnetic anisotropy. The magnetic moments of the first pinning layer 22 and the second pinning layer 34 are opposite in direction, which can be achieved by applying magnetic fields of different magnitudes and opposite directions, but perpendicular to the chip plane. Due to interlayer coupling, the magnetic moments of the first reference layer 24 and the second reference layer 32 are opposite to those of the first pinning layer 22 and the second pinning layer 34, respectively. Therefore, the magnetic moments of the first reference layer 24 and the second reference layer 32 are also opposite in direction.

[0058] The magnetic moments of the reference layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 are parallel and opposite, that is, the magnetic moments of the first reference layer 24 and the second reference layer 32 are parallel and opposite, so that the resistance changes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 are opposite under the same magnetic field.

[0059] When the first reference layer 24 and the second reference layer 32 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 3 changes in the opposite mode to the magnetic field, thereby realizing a Wheatstone half bridge.

[0060] Please refer to Figure 2 and Figure 3 The 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 3 are as follows: Figure 3As shown in the left-middle figure, at this time, the magnetic moment of the free layer 26 of the first magnetic tunnel junction is parallel to the magnetic moment of the first reference layer 24, exhibiting a low resistance value. The magnetic moment of the free layer 26 of the second magnetic tunnel junction is antiparallel to the magnetic moment of the second reference layer 32, exhibiting a high resistance value. When the magnetic field direction turns to +z, the magnetic moment directions of the magnetic layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 are as follows: Figure 3 As shown in the right-middle figure, the resistance of the first magnetic tunnel junction changes to a high resistance value, while the resistance of the second magnetic tunnel junction changes to 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, which is perpendicular to the upper surface of the chip.

[0061] The reason why the width of the first magnetic tunnel junction device 2 is greater than the width of the second magnetic tunnel junction device 3 is that the signal of the magnetic sensor needs to be extracted from the middle free layer 26, and the signal extraction part 8 extracts the signal from the free layer 26.

[0062] It should be noted that the shapes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 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 3 are in the same direction. For example, the shapes of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 can be cylindrical or elliptical. When it is cylindrical, the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 is the diameter. When it is elliptical, the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 is the major axis or the minor axis. The major axis width of the elliptical cylinder is generally between 1 micrometer and 20 micrometers, and the minor axis width is generally between 0.1 micrometer and 10 micrometers.

[0063] Furthermore, the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 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 3 are both parallel to the y-axis, or both are parallel to the x-axis.

[0064] The absolute value of the width of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 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 8.

[0065] The first mask layer 4 is a conductive film layer, and the material of the first mask layer 4 can be any one of tantalum, tantalum nitride, titanium nitride, etc.

[0066] The bottom electrode 1 can be made of tantalum nitride or titanium nitride, etc., and the top electrode 7 can also be made of tantalum nitride, titanium nitride, etc.

[0067] The first insulating layer 5 includes:

[0068] The first insulating unit layer 51 is disposed around the second magnetic tunnel junction device 3;

[0069] A second insulating unit layer 52 is disposed on the outer surface of the first insulating unit layer 51.

[0070] The first insulating unit layer 51 serves a protective function. The material can be silicon nitride, and the thickness can be 5 nanometers to 20 nanometers.

[0071] The second insulating unit layer 52 is an oxide insulating layer, such as silicon dioxide, silicon oxynitride, etc.

[0072] The material of the second insulating layer 6 can be silicon nitride, and the material of the signal lead-out part 8 can be a metal material, such as cobalt, ruthenium, copper, tungsten, etc.

[0073] In the magnetic sensor of this application, the device group is disposed on a chip. The dual magnetic tunnel junction in the device group includes a first magnetic tunnel junction device 2 and a second magnetic tunnel junction device 3. The width of the first magnetic tunnel junction device 2 is greater than the width of the second magnetic tunnel junction device 3, and the magnetic moment directions of the reference layers in the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 are parallel and opposite. This makes the resistance of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 change in opposite directions under the same magnetic field. That is, the dual magnetic tunnel junction can be directly formed into a Wheatstone half-bridge on the chip without the need for packaging multiple chips. The chip can be directly used as the chip of the magnetic sensor. Furthermore, the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 are stacked vertically, reducing the area occupied on the chip and thus reducing the area of ​​the magnetic sensor. The vertical stacking of the first magnetic tunnel junction device 2 and the second magnetic tunnel junction device 3 avoids setting MTJ devices with different resistance characteristics at different positions on the chip, simplifying the process flow.

[0074] 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 3 are connected in series, and both the first preset number and the second preset number are less than the number of device groups.

[0075] This application does not limit the first preset quantity and the second preset quantity; they can be set by the user.

[0076] Multiple first magnetic tunnel junction devices 2 and multiple second magnetic tunnel junction devices 3 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 4As shown, from left to right, the second magnetic tunnel junction device 3 in the three device groups on the left is connected in series, and from right to left, the first magnetic tunnel junction device 2 in the three device groups on the right is connected in series. The signal is output from the signal lead-out part 8 in the middle device group.

[0077] 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 3 are connected in series.

[0078] This application does not limit the number of the third and fourth preset quantities; these can be set by the user.

[0079] 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 17 As shown.

[0080] This application also provides a method for manufacturing a magnetic sensor; please refer to [reference needed]. Figure 5 The method includes:

[0081] Step S101: Form the bottom electrode on the chip.

[0082] Step S102: A dual magnetic tunnel junction to be processed is prepared on the upper surface of the bottom electrode. The dual magnetic tunnel junction to be processed includes a first magnetic tunnel junction device to be processed and a second magnetic tunnel junction device to be processed, stacked from bottom to top.

[0083] Please refer to the following steps. Figure 6 The first magnetic tunnel junction device 2' and the second magnetic tunnel junction device 3' to be processed are stacked on top of the bottom electrode 1.

[0084] The first magnetic tunnel junction device 2' to be processed includes, from bottom to top, a seed layer, a first pinning layer, a first coupling layer, a first reference layer, a first barrier layer, and a free layer. The second magnetic tunnel junction device 3' to be processed includes, from bottom to top, a free layer, a second barrier layer, a second reference layer, a second coupling layer, a second pinning layer, and a capping layer. The first magnetic tunnel junction device 2' and the second magnetic tunnel junction device 3' share the free layer. The first magnetic tunnel junction device 2' to be processed is electrically connected to the bottom electrode.

[0085] Step S103: Etch the first magnetic tunnel junction device to be processed and the second magnetic tunnel junction device to be processed to form the first magnetic tunnel junction device and the second magnetic tunnel junction device, wherein the width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device.

[0086] Step S1031: A first mask layer to be processed is formed on the upper surface of the second magnetic tunnel junction device to be processed, and then the first mask layer to be processed is etched to form a first mask layer 4 with a width of D2, as shown. Figure 7 As shown, etching methods can include dry etching, such as reactive ion etching and ion beam etching.

[0087] Step S1032: Using the first mask layer as a mask, etch the second magnetic tunnel junction device to be processed down to the free layer in the double magnetic tunnel junction to obtain the second magnetic tunnel junction device.

[0088] This application does not limit the etching method for the second magnetic tunnel junction device to be etched, but depends on the situation, such as dry etching or wet etching.

[0089] When etching the second magnetic tunnel junction device to be processed down to the free layer, the location where the etching stops is not specifically limited in this application. For example, the etching can stop at the interface between the free layer and the second barrier layer in the second magnetic tunnel junction device to be processed, or the free layer can be etched beyond the interface. The etching depth of the free layer is between 1 nanometer and 2 nanometers.

[0090] This step takes etching beyond the interface between the free layer and the second barrier layer as an example. The resulting schematic diagram of the second magnetic tunnel junction device 3 is shown below. Figure 8 As shown.

[0091] Step S1033: Form a first insulating unit layer 51 on the upper surface of the first magnetic tunnel junction device to be processed and around the second magnetic tunnel junction device, such as... Figure 9 As shown, the thickness of the first insulating unit layer 21 can be between 5 nanometers and 20 nanometers.

[0092] Step S1034: On the outer surface of the first insulating unit layer 51, the second insulating unit layer 52, as shown... Figure 10 As shown.

[0093] Step S1035: Use chemical mechanical polishing to smooth the surface until the surface of the first mask layer is exposed. Figure 11 As shown.

[0094] Step S1036: A second mask layer is formed on the upper surface of the first mask layer. The width of the second hard mask layer is greater than the width of the second magnetic tunnel junction device. Then, photolithography and etching are performed. The etching method can be reactive ion etching or ion beam etching to form a second mask layer 9 with a width of D1, where D1 > D2 and is larger than the diameter of the bottom electrode. Please refer to the schematic diagram after the formation of the second mask layer. Figure 12 .

[0095] Step S1037: Using the second mask layer as a mask, etch the first insulating layer and the first magnetic tunnel junction device to be processed to form the first magnetic tunnel junction device, such as... Figure 13 As shown.

[0096] The etching of the first insulating layer and the first magnetic tunnel junction device to be processed includes:

[0097] The first insulating layer and the first magnetic tunnel junction device to be processed are etched using a dry etching method to form the first magnetic tunnel junction device. The dry etching method can be ion beam etching, reactive ion etching, etc.

[0098] Step S1038: Form the second insulating layer 6' to be processed on the upper surface of the second mask layer, the first magnetic tunnel junction device, and the side surface of the first insulating layer. Please refer to [reference needed]. Figure 14 It should be noted that an interlayer oxide insulating layer is also formed on the outer surface of the second insulating layer 6' to be treated. Figure 14 Not shown in the image.

[0099] Step S1039: The upper surfaces of the second mask layer 9 and the second insulating layer 6' to be treated are ground smooth using a chemical mechanical planarization method until the upper surface of the first hard mask layer is exposed, forming the second insulating layer, as shown. Figure 15 As shown.

[0100] Step S104: Fabricate a top electrode above the second magnetic tunnel junction device.

[0101] Please refer to the following steps. Figure 16 The top electrode 7 is located on the upper surface of the first mask layer.

[0102] Step S105: Prepare a signal lead-out section connected to the free layer in the dual magnetic tunnel junction.

[0103] A through-hole is formed in the first insulating layer, and a material is deposited in the through-hole to form a signal lead-out portion. The through-hole can be fabricated using the damascus process. Finally, chemical mechanical planarization is used to grind the surface until the top electrode is exposed. Please refer to the schematic diagram of the structure obtained in this step. Figure 1 .

[0104] Step S106: 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.

[0105] Step S107: Magnetize the first magnetic tunnel junction device or the second magnetic tunnel junction device using a second magnetic field that is opposite in direction and of different magnitude from 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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 dual magnetic tunnel junction electrically connected to the bottom electrode, the dual magnetic tunnel junction comprising a first magnetic tunnel junction device and a second magnetic tunnel junction device stacked from bottom to top, wherein the width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device, and 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; the first magnetic tunnel junction device comprises a first reference layer, a first barrier layer, and a free layer stacked from bottom to top, and the second magnetic tunnel junction device comprises a free layer, a second barrier layer, and a second reference layer stacked from bottom to top, wherein the first magnetic tunnel junction device and the second magnetic tunnel junction device share a free layer; The top electrode is located above the second magnetic tunnel junction device; A signal lead-out section connected to the free layer in the dual magnetic tunnel junction; A first mask layer is disposed on the upper surface of the second magnetic tunnel junction device; A first insulating layer is disposed around the second magnetic tunnel junction device and flush with the upper surface of the first mask layer, and the signal lead-out portion penetrates the first insulating layer; A second insulating layer is disposed on the side of the first magnetic tunnel junction device and the first insulating layer; The first insulating layer includes: A first insulating unit layer is disposed around the second magnetic tunnel junction device; A second insulating unit layer is disposed on the outer surface of the first insulating unit layer; The major axes of the first magnetic tunnel junction device and the second magnetic tunnel junction device are in the same direction. The first magnetic tunnel junction device and the second magnetic tunnel junction device are elliptical cylinders or cylinders; when they are elliptical cylinders, the width of the first magnetic tunnel junction device and the second magnetic tunnel junction device is the major axis or the minor axis, the major axis width of the elliptical cylinder is 1 micrometer to 20 micrometers, and the minor axis width is 0.1 micrometer to 10 micrometers. 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 material of the first mask layer is any one of tantalum, tantalum nitride, and titanium nitride.

3. The magnetic sensor as described in claim 1, characterized in that, The bottom electrode is made of tantalum nitride or titanium nitride.

4. A method for manufacturing a magnetic sensor, used in the magnetic sensor as described in any one of claims 1 to 3, characterized in that, include: A bottom electrode is formed on the chip; A dual magnetic tunnel junction to be processed is fabricated on the upper surface of the bottom electrode. The dual magnetic tunnel junction to be processed includes a first magnetic tunnel junction device to be processed and a second magnetic tunnel junction device to be processed, stacked from bottom to top. The first magnetic tunnel junction device and the second magnetic tunnel junction device to be processed are etched to form the first magnetic tunnel junction device and the second magnetic tunnel junction device, wherein the width of the first magnetic tunnel junction device is greater than the width of the second magnetic tunnel junction device. A top electrode is fabricated above the second magnetic tunnel junction device; Prepare a signal lead-out section that is connected to the free layer in the dual magnetic tunnel junction; 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.

5. The method for manufacturing a magnetic sensor as described in claim 4, characterized in that, When etching the second magnetic tunnel junction device to be processed, the etching depth of the free layer is between 1 nanometer and 2 nanometers.

6. The method for manufacturing a magnetic sensor as described in claim 4 or 5, characterized in that, The etching of the first magnetic tunnel junction device to be processed and the second magnetic tunnel junction device to be processed includes: The first magnetic tunnel junction device and the second magnetic tunnel junction device to be processed are etched using a dry etching method.

Images