Magnetic multi-turn sensor and manufacturing method

Abstract

To provide a magnetic multi-turn sensor comprising a continuous coil of magnetoresistive elements and a method of manufacturing the sensor.SOLUTION: The continuous coil is formed on a substrate such as a silicon wafer that has been fabricated to form a trench and bridge arrangement that enables the inner and outer spirals to be connected without interfering with the magnetoresistive elements of the spiral winding in between. Once the substrate has been fabricated with the trench and bridge arrangement, a film of the magnetoresistive material can be deposited to form a continuous coil on the surface of the substrate, where a portion of the coil is formed in the trench and a portion of the coil is formed on the bridge.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims the benefit of priority from U.S. Provisional Patent Application No. 63 / 075453, filed on September 8, 2020, the entire content of which is incorporated herein by reference.

[0002] The present disclosure relates to a magnetic multi-turn sensor. In particular, the present disclosure relates to a closed-loop magnetic multi-turn sensor and a method of manufacturing the same. [Background Art]

[0003] Magnetic multi-turn sensors are commonly used in applications where it is necessary to monitor the number of times a device has been rotated. An example is a vehicle steering wheel. Magnetic multi-turn sensors typically include magnetoresistive elements that are sensitive to an applied external magnetic field. The resistance of the magnetoresistive element can be changed by rotating the magnetic field within the vicinity of the sensor. Variations in the resistance of the magnetoresistive element can be tracked to determine the number of rotations in the magnetic field, which can be converted into the number of rotations in the monitored device.

[0004] Magnetic multi-turn sensors typically comprise a plurality of magnetoresistive elements laid out as strips in a spiral or closed-loop configuration. One advantage of closed-loop multi-turn sensors is that they effectively provide a large number of spirals connected together, thus making it possible to count a very large number of rotations. [Summary of the Invention] [Means for Solving the Problems]

[0005] This disclosure provides a magnetic multi-turn sensor including a continuous coil of magnetoresistive elements and a method for manufacturing the sensor. The continuous coil is formed on a substrate such as a silicon wafer fabricated to form a trench and bridge arrangement that allows an inner spiral and an outer spiral to be connected without interference with the magnetoresistive elements of the spiral windings between them. Once the substrate is fabricated in a trench and bridge arrangement, a film of magnetoresistive material can be deposited to form a continuous coil on the surface of the substrate, with a portion of the coil formed in the trenches and a portion of the coil formed on the bridges.

[0006] The first embodiment provides a magnetic multi-turn sensor comprising: a plurality of magnetoresistive sensor elements connected in series and arranged in a continuous spiral configuration; a substrate on which the plurality of magnetoresistive elements are formed, the substrate having trenches configured to receive at least one magnetoresistive element; and at least one bridge formed on the trenches, configured to support at least one magnetoresistive element.

[0007] The trench may be configured to receive a plurality of magnetoresistive elements defining one side of a continuous spiral, and the substrate includes a bridge configured to receive a single magnetoresistive element connecting the inner loop and the outer loop of the spiral.

[0008] The trench may be configured to receive one magnetoresistive element connecting the inner and outer loops of the spiral, and the substrate may include at least one bridge formed on the trench to receive a plurality of magnetoresistive elements defining one side of the spiral.

[0009] The substrate may include a plurality of bridges formed on the trench to receive a plurality of magnetoresistive elements defining one side of the spiral, each bridge receiving one magnetoresistive element.

[0010] The magnetoresistive element may be one of the following: a giant magnetoresistance (GMR) element or a tunnel magnetoresistance (TMR) element.

[0011] The substrate may comprise a wafer layer, an intermediate layer formed on the wafer layer, and a mask layer formed on the intermediate layer.

[0012] The trench may be formed by removing a portion of the intermediate layer and a portion of the mask layer.

[0013] The bridge may be formed by preserving a portion of the mask layer above the trench.

[0014] The wafer layer may comprise one of a silicon layer, a glass layer, or a sapphire layer.

[0015] The intermediate layer may comprise one of an oxide layer, a nitride layer, and an oxynitride layer.

[0016] The mask layer may include an episilicon layer.

[0017] The mask layer may include a hard mask layer for selective etching.

[0018] The mask layer may comprise one of a silicon oxide layer, a silicon oxynitride layer, and a silicon nitride layer.

[0019] A further embodiment provides a method for manufacturing a closed-loop magnetic multi-turn sensor, the method comprising: forming a substrate comprising a wafer, an intermediate layer, and a mask layer; etching regions of the mask layer and the intermediate layer to form trenches in the substrate, wherein one or more portions of the mask layer are preserved to form at least one bridge on the trenches; and depositing a magnetoresistive film on the substrate to form a continuous spiral of magnetoresistive elements, wherein at least one magnetoresistive element is formed in the trenches.

[0020] At least one magnetoresistive element may then be formed on at least one bridge.

[0021] A plurality of magnetoresistive elements may be formed in the trench to define one side surface of a spiral, and at least one magnetoresistive element formed on at least one bridge connects an inner loop and an outer loop of the spiral.

[0022] Alternatively, a plurality of magnetoresistive elements may be formed on at least one bridge to define one side surface of a spiral, and at least one magnetoresistive element formed in the trench connects an inner loop and an outer loop of the spiral.

[0023] Etching regions of the mask layer and the intermediate layer may further comprise forming ramps in the mask layer and the intermediate layer at each end of the trench.

[0024] The etching of the regions of the mask layer and the intermediate layer may comprise lithographic etching.

[0025] Depositing the magnetoresistive film may comprise using a tilted and rotational deposition system.

[0026] The method may further comprise etching the magnetoresistive film to form the magnetoresistive element.

[0027] Ion beam etching or angled reactive ion (RIE) etching may be used to form at least one magnetoresistive element in the trench.

[0028] In some cases, the wafer layer comprises a glass layer or a sapphire layer, and in this case depositing the magnetoresistive film may comprise depositing a layer of photoresist material, depositing a layer of magnetoresistive film, and directing ultraviolet light from under the substrate to lift off one or more portions of the photoresist material and the magnetoresistive film.

[0029] The intermediate layer may comprise one of an oxide layer, a nitride layer, and an oxynitride layer.

[0030] The mask layer may comprise an epitaxial silicon layer.

[0031] The mask layer may comprise a hard mask layer for selective etching. For example, the hard mask layer may comprise one of a silicon oxide layer, a silicon oxynitride layer, and a silicon nitride layer.

[0032] In such a case, the selective etching solution is applied to etch a region of the intermediate layer under a region of the hard mask layer to form at least one bridge. For example, the selective etching solution may comprise one of potassium hydroxide (KOH), ethylenediamine pyrocatechol (EDP), or tetramethylammonium hydroxide (TMAH).

[0033] Another arrangement described herein provides a magnetic multi-turn sensor comprising: a plurality of magnetoresistive sensor elements connected in series and arranged in a continuous spiral configuration; and a substrate on which the plurality of magnetoresistive elements are formed, the substrate comprising at least one bridge formed on a first portion of the magnetoresistive elements, the at least one bridge being configured to support at least one magnetoresistive element.

[0034] The bridge may be formed from a strip of magnetic material on the first portion of the magnetoresistive element, and the magnetic material may be a soft ferromagnetic material. For example, the magnetic material may be a soft magnetic material comprising one of nickel, iron, or cobalt, or an alloy containing at least one of nickel, iron, or cobalt.

[0035] The first portion of the magnetoresistive element may be multiple magnetoresistive elements defining one side of a continuous spiral, and the bridge is configured to receive one magnetoresistive element connecting the inner loop and the outer loop of the spiral.

[0036] Next, this disclosure will be described only by reference to the attached drawings. [Brief explanation of the drawing]

[0037] [Figure 1] This invention shows a magnetic multi-turn sensor according to one embodiment of the present disclosure. [Figure 2] Further details of a magnetic multi-turn sensor according to one embodiment of the present disclosure are provided. [Figure 3] Further embodiments of the present disclosure further illustrate a magnetic multi-turn sensor. [Figure 4A] This is a schematic side view illustrating a method for manufacturing a magnetic multi-turn sensor according to an embodiment of the present disclosure. [Figure 4B] This is a schematic side view illustrating a method for manufacturing a magnetic multi-turn sensor according to an embodiment of the present disclosure. [Figure 4C] This is a schematic side view illustrating a method for manufacturing a magnetic multi-turn sensor according to an embodiment of the present disclosure. [Figure 4D] This is a schematic side view illustrating a method for manufacturing a magnetic multi-turn sensor according to an embodiment of the present disclosure. [Figure 5] Further embodiments of the present disclosure show a magnetic multi-turn sensor. [Figure 6] This figure illustrates the electrical connection of a magnetic multi-turn sensor according to one embodiment of the present disclosure. [Figure 7] This invention describes a method for connecting a magnetoresistive sensing element of a multi-turn sensor according to one embodiment of this disclosure. [Figure 8A] A further method for connecting a magnetoresistive sensing element of a multi-turn sensor, according to one embodiment of the present disclosure, is shown. [Figure 8B] A further method for connecting a magnetoresistive sensing element of a multi-turn sensor, according to one embodiment of the present disclosure, is shown. [Figure 9A]A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 9B] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 10A] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 10B] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 10C] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 10D] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 11A] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 11B] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 11C] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 11D] Further methods for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure are shown. [Figure 12] This disclosure describes a method for manufacturing a magnetic multi-turn sensor according to an embodiment of this disclosure. [Figure 13] This shows a portion of a magnetic multi-turn sensor according to one embodiment of the present disclosure. [Figure 14] A portion of a magnetic multi-turn sensor according to a further embodiment of the present disclosure is shown. [Figure 15A] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 15B] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 16A] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 16B] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 17A] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 17B] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 18A] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Figure 18B] A method for manufacturing a magnetic multi-turn sensor according to embodiments of this disclosure is further described. [Modes for carrying out the invention]

[0038] Magnetic multi-turn sensors can be used to monitor the rotation count of a rotating shaft. To do this, a magnet is typically mounted on the end of the rotating shaft, and the multi-turn sensor is sensitive to the rotation of the magnetic field as the magnet rotates with the shaft. Such magnetic sensing can be applied to a wide variety of applications, including automotive, medical, industrial control, consumer, and numerous other applications that utilize information about the position of rotating parts.

[0039] Magnetic multi-turn sensors typically include giant magnetoresistance (GMR) or tunnel magnetoresistance (TMR) elements that are sensitive to an applied external magnetic field, arranged in a spiral or closed-loop configuration. As the external magnetic field rotates, magnetic domain walls propagate through the spiral, thereby changing the magnetic alignment as each magnetoresistive element passes through. The resistance of the magnetoresistive elements changes as the magnetic alignment changes, and the variation in resistance is tracked to determine the number of rotations of the magnetic field. One of the main advantages of closed-loop sensors is that they effectively provide a large number of spirals connected together, thus enabling the counting of a very large number of rotations. However, fabricating such sensors presents many challenges, as the thinness of the magnetoresistive film can make it difficult to connect the inner and outer spirals, and connecting wires crossing the rest of the spiral can damage the magnetic domain walls, leading to non-propagation and corrupted rotation counts.

[0040] This disclosure provides a magnetic multi-turn sensor comprising a continuous coil of magnetoresistive elements and a method for manufacturing the sensor that enables the connection of an inner spiral and an outer spiral without interference between the magnetoresistive elements. The continuous coil is formed on a substrate such as a silicon wafer fabricated to form a trench and bridge arrangement that provides a shielded intersection above or below the spiral. Once the substrate is fabricated in the trench and bridge arrangement, a film of magnetoresistive material can be deposited to form the continuous coil on the surface of the substrate. In doing so, a multi-turn sensor comprising a continuous coil is provided that can measure a large number of rotations using no power or very little power. The non-volatile properties of the magnetic domain positions, i.e., the pattern in which the magnetic domains of the magnetoresistive element change as the domain walls propagate through the spiral, enable the multi-turn sensor to count the number of rotations in an external magnetic field without power. As the magnetic field rotates, each magnetic domain of the magnetoresistive element changes in a specific pattern, which provides a corresponding pattern of resistance measured across the multi-turn sensor. Power can then be supplied when a readout is needed, and the measured resistance at that point corresponds to a specific point in the pattern, i.e., a specific number of rotations.

[0041] Figures 1 and 2 show a multi-turn sensor 1 according to one embodiment of the present disclosure. The sensor 1 comprises a silicon-based substrate having a surface 11, for example, a substrate surface 11, which is formed by etching the substrate surface 11 to form a trench 12 in one region of the substrate surface 11, as shown in more detail, for example, in Figure 2. The trench 12 is formed such that a portion of the substrate surface 11 is preserved to form a bridge 14 on the trench 12. Next, a film of magnetoresistive material can be deposited on the substrate 10 to form a magnetoresistive track 16 arranged in a spiral configuration having a plurality of segments arranged in series with each other. Thus, each arm of the spiral provides a magnetoresistive sensing element that can change its resistance in response to a change in magnetic alignment state in the presence of an externally applied magnetic field. The magnetoresistive track 16 defining one side 15 of the spiral is arranged to pass through the trench 12 and under the bridge 14. Each end of the trench 12 may be provided with ramps 13A, 13B to provide a smooth path from the bottom of the trench 12 to the upper substrate surface 11, allowing the magnetoresistive track 16 to enter and exit the trench 12.

[0042] To form the bridge 14, the trench 12, and the ramps 13A and 13B leading into and out of the trench 12, the substrate 10 may be etched using a multi-stage lithography etching process. For example, this could be a first lithography exposure and etching for the body of the trench 12, a second lithography exposure and etching for the ramps 13A and 13B of the trench 12, and a third lithography exposure and etching for the planar surface 11 surrounding the trench 12 and the bridge 14.

[0043] The outer spiral winding 17 passes around the outer perimeter of the trench 12 and connects to the inner spiral winding 19 via a connecting magnetoresistive track 18 deposited on the bridge 14. Thus, this bridge 14 and trench 12 arrangement allows the connecting magnetoresistive track 18 to traverse one side 15 of the spiral without interfering with the magnetic domain propagation of the magnetoresistive track on that side 15. Preferably, the connecting magnetoresistive track 18 is a magnetoresistive track that contributes to the rotation count of the multi-turn sensor; however, in other arrangements, it will be understood that the connecting portion may include some other soft ferromagnetic material.

[0044] In an alternative arrangement, as shown in Figure 3, the sensor 2 has a narrow trench 22 formed in the substrate 20, providing a crossing for the connecting magnetoresistive track 28 from the inner spiral winding to the outer spiral winding, and one or more bridges 24 formed above the narrow trench 22 supporting the magnetoresistive track 25 on its side of the spiral. That is, the magnetoresistive track 25 of the spiral crosses over the connecting magnetoresistive track 28. In the example of Figure 3, one wide bridge 24 is formed supporting all of the magnetoresistive tracks 25 that form one side of the spiral. In other arrangements, several individual bridges may be formed above the narrow trench 22, each supporting a single magnetoresistive track 25. As described above, the trench 22 and bridge 24 arrangement may be formed by etching the substrate 20.

[0045] Figures 4A-D show the first step in a method for fabricating a multi-turn sensor according to embodiments of the present disclosure. As shown in Figure 4A, the substrate is fabricated by first growing or depositing an intermediate layer 202, preferably an oxide layer, on a silicon wafer 200. However, the wafer 200 may be formed from an ultraviolet-transmitting material such as glass or sapphire, in which case it will be understood that the oxide layer 202 is deposited thereon. The oxide layer 202 may also be a layer of nitride, oxynitride, or similar material. A mask layer 204, for example, episilicon or a similar material, is then deposited on the oxide layer 202. The thickness of the mask layer 204 depends at least in part on the thickness of the bridge 24.

[0046] Next, as shown in Figure 4B, the photoresist layer 206 is formed on the substrate to etch the trench 208, as shown in Figure 4C, and the oxide layer 202 is removed to deepen the trench 208 to a specific depth. As shown in Figure 4D, a portion of the mask layer 204 is saved to form a bridge 210 on the trench 208. The trench 208 and bridge 210 may also be etched using stepwise lithographic etching. For example, a first lithographic exposure and etching for the body of the trench 208, a second lithographic exposure and etching for the lamp of the trench 208 (i.e., lamps 13A and 13B in Figures 1-3), and a third lithographic exposure and etching for the planar surface surrounding the trench 208 (i.e., top surface 11 and bridge 14 in Figures 1-3).

[0047] The method of forming trenches is further illustrated by Figures 9A and 9B. As shown in Figure 9A, the substrate is a wafer 900 formed of silicon with a Miller index of (100), or includes an ultraviolet-transmitting material such as glass or sapphire. An oxide layer 902 is formed on the wafer 200, followed by the formation of a mask layer 904 formed from episilicon or the like. As previously described, a resist 906 is deposited on the substrate, a pattern 908 is formed on the resist, exposing the areas to be trenches and defining the bridges. Next, the mask layer 904 and the oxide layer 902 are etched to form trenches 910 and bridges 912, as shown in Figure 9B. A single narrow bridge 912 with a wide trench 910 is shown, but it will be understood that, of course, any appropriate number and size of bridges and trenches may be formed by using an appropriate pattern on the resist.

[0048] When an ultraviolet-transparent material such as glass or sapphire is used as the substrate, a lift-off process may be used to form magnetoresistive tracks in the trenches and on the bridges, as shown in Figures 10A-10D. Within the exposed trench portions, a photoresist material 1002 may be sprayed onto the transparent substrate 1000, as shown in Figure 10A. Next, a layer of magnetoresistive material 1004 is deposited on the substrate 1000 and the photoresist material 1002, as shown in Figure 10B. Then, a lift-off process and resist removal are performed, as shown in Figures 10C and 10D, so that ultraviolet light from below and above the substrate 1000 is used to remove the photoresist material 1002 and lift off a portion of the magnetoresistive material 1004, with the remaining magnetoresistive material 1004 forming the tracks of the multi-turn sensor.

[0049] An alternative method for forming bridge and trench configurations is to use a bulk micromachining approach, where bridges are formed by a hard mask layer and selective etching. In such a case, the substrate (i.e., silicon wafer 200 and oxide layer 202) is provided with a hard mask layer, such as silicon oxide, silicon oxynitride, and silicon nitride, which is inert to the etching solution used to form the trenches (e.g., potassium hydroxide (KOH), ethylenediamine pyrocatechol (EDP), or tetramethylammonium hydroxide (TMAH)). By using a selective etching solution that attacks the oxide layer 202 rather than the mask layer, it becomes possible to form trenches beneath the bridges.

[0050] During this process, special attention must be paid to the orientation of the bridge relative to the crystal orientation of the substrate. The bridge needs to be tilted relative to the {110} plane, as the {111} plane acts as a natural etching stop. Then, the sidewall profile can be smoothed and the bottom of the trench can be flattened using "n" isotropic etching. Another option is to tilt the substrate under the bridge so that the trench is oriented at an angle to the {110} plane, such that the {111} plane has a different orientation toward the trench opening.

[0051] An example of this bulk micromachining approach is shown in Figures 11A–11D. As shown in Figure 11A, a wafer 1100 and an oxide layer 1102 are provided. The wafer 1100 is formed from silicon having a Miller index of (110), and the long edge is, <112> Aligned in the direction, the shorter side is, <111> They align in a particular direction. <112> Direction <110> The angle from the surface is 54.74°, creating a ramp perpendicular to the longer side and 35.3° to the shorter side.

[0052] As shown in Figure 11B, a masking layer 1104, formed from an oxide or nitride (such as those mentioned above), is formed on the oxide layer 1102. Next, as shown in Figure 11C, an etching solution (such as a KOH etching solution) is used to etch the trenches 1106 and bridges 1108, with the depth of the trenches 1106 depending on the time spent in the etching solution. In some cases, as shown in Figure 11D, the bridges 1108 may need to be formed at a certain angle due to the etching solution leaving facets beneath them. By tilting the masking layer 1104, this allows the undercuts to form the bridges 1108, and the wafer portion of the bridges 1108 has walls tilted at an angle of, for example, 35 degrees. This also facilitates access to the area directly beneath the bridges 1108, thereby facilitating the uniform deposition of the magnetoresistive material within the trenches 1106. Similarly, the masking layer 1104 within the area of ​​trench 1106 may also be inclined to form the inclined walls of trench 1106, which may again be at an angle of 35 degrees. However, it will be understood that the inclined walls of trench 1106 and bridge 1108 may be at any suitable angle.

[0053] The widths of the trench 208 and bridge 210 depend at least in part to the number of magnetoresistive tracks formed along the trench. If the trench 208 accommodates one side of the spiral, as shown in Figures 1-3, then the width of the trench 208 depends at least in part to how many windings the spiral has and the spacing between each set of tracks, while the bridge 210 can be wide enough to support the tracks connecting the inner and outer spiral windings. If the trench 208 is positioned to accommodate the tracks connecting the inner and outer spiral windings, then the trench 208 can be wide enough to accommodate one track. In such a case, as shown in Figure 14, one bridge 1404 formed on the trench 1402 is wide enough to accommodate all the tracks 1408 on its side of the spiral, while the trench 1402 is wide enough to accommodate the connecting track 1406. Alternatively, as shown in Figure 13, several bridges 1304 may be formed to accommodate each track 1308 individually.

[0054] In either case, the bridge 210 should be as narrow as possible to limit the amount of shadowing, while the trench 208 should preferably be as wide as possible to reduce the shadowing effect. For example, for a magnetoresistive track with a width of 350 nm, a bridge 210 of about 3 μm and a trench of about 29 μm may be provided. Similarly, if there are multiple tracks running parallel to each other along a trench or across one or more bridges, the tracks should be spaced at an appropriate distance from each other so as not to interfere with one another.

[0055] The depth of trench 208 should also be chosen to minimize the amount of shadowing, while simultaneously allowing the magnetoresistive track to easily enter and exit trench 208.

[0056] It will be understood that other suitable fabrication methods may be used to etch the trench and bridge arrangements. For example, the ramps at either end of a trench may be formed using a "bird's beak" as a fabrication process. Similarly, microlenses may be used in lithographic exposure to etch the trenches beneath the bridges.

[0057] Once the substrate is formed in a trench and bridge configuration, a film of magnetoresistive material may be deposited on the substrate and etched to form magnetoresistive tracks 16 as shown in Figures 1-3.

[0058] The thickness of the magnetoresistive track affects the operating behavior in an externally applied magnetic field, such as a magnetic field strength window in which a resistor changes its magnetic alignment. Therefore, it is important that the magnetoresistive film is deposited uniformly to provide a track of uniform thickness, thereby preventing errors in rotation counts. To deposit the film in a uniform layer beneath the bridge, angled physical deposition can be used, where the sputtering system is angled and the substrate rotates. Figure 12 shows a cross-section of a wafer 1200 with a bridge 1204 and a trench 1206 formed thereon, and a substrate with an oxide layer 1202. Film 1208 is deposited on the bridge 1204 and within the trench 1206 so that a track of uniform thickness is formed. This is done by tilting the sputtering system at different angles depending on the target area. For example, 90° relative to wafer 1200 may be used to deposit film 1208 on the bridge 1204, and the smallest angle is then used to deposit film 1208 directly beneath the bridge 1204 in the area indicated by 1210. Using the same angle for all areas means a thinner film on the ramp portion of trench 1206, which has potential pinning or discontinuities within area 12010. Thus, the inclination angle can be selected so that the film is uniformly deposited beneath the bridge without any shadowing caused by the bridge and trench walls.

[0059] In some configurations, angled deposition may be performed on the free layer of the magnetoresistive film. In some configurations, angled deposition may be performed only on the free layer of the magnetoresistive film, i.e., on a ferromagnetic material that has a magnetization that changes direction freely, thereby providing a change in resistance as the external magnetic field rotates. Therefore, since this is the magnetization of this portion of the magnetoresistive stack being measured, it is important that this portion of the film is uniform to ensure consistent readings.

[0060] Once the film is uniformly deposited, it is etched to form tracks, for example, using ion beam etching or reactive ion etching. For the portion beneath the bridge, reactive ion etching may be performed at an angle that re-etches the film within a uniform manor. Of course, it will be understood that any suitable angle may be used depending on the trench depth and the bridge thickness. Similarly, it will be understood that other methods for etching the tracks may also be used.

[0061] In some cases, once a magnetoresistive film is deposited in the trench and etched to provide a magnetoresistive track for the sensor spiral, the trench can be filled with polyimide material, which may help provide mechanical robustness to the structure during any subsequent processing steps.

[0062] Figures 15A-B to 18A-B further illustrate how a magnetoresistive track is formed when a bridge 1504 is configured to receive a magnetoresistive track 1508 on one side of the spiral, while a trench 1502 is positioned to receive a single track 1506 connecting the inner and outer spiral windings.

[0063] The first step in the method is shown in Figures 15A and 15B. Here, Figure 15B shows a cross-sectional view of Figure 15A looking down the length of the trench 1502 perpendicular to axis A. First, the magnetoresistive material is blanket-deposited on the substrate 1500, so that the magnetoresistive material is deposited on the bridge 1504 and along the trench 1502. Next, a lithography pattern is used to etch multiple tracks 1508 along the bridge 1504 and a single track 1506 along the trench 1502. The trench 1502 is formed to have the same width as the target width of the magnetoresistive track 1506, and therefore it is not necessary to define the width of the track 1506 during lithographic etching. However, areas of the magnetoresistive material 1510 may be left on the side walls of the trench 1502.

[0064] To address this, the width of the trench 1502 within the area of ​​bridge 1504 is widened, as shown in Figures 16A and 16B. Again, Figure 16B shows a cross-sectional view of Figure 16A overlooking the length of trench 1502. The overlapping areas of the magnetoresistive material 1510 may then be removed using some suitable method, for example, eco-snow cleaning technique or ion beam etching, thereby providing a single magnetoresistive track 1506 running along the length of the trench, as shown in Figures 17A-17B and 18A-18B.

[0065] Figure 5 provides an alternative embodiment of the present disclosure in which, although no trench is formed in the substrate, a bridge 52, for example, a permalloy strip or bridge formed using any of the methods described herein, is formed on the spiral magnetoresistive track 58 to connect the inner and outer spiral windings 54, 56. In such an arrangement, the bridge 52 may be formed from a soft magnetic material, preferably a soft ferromagnetic material, which includes one of nickel, iron, or cobalt, or an alloy containing at least one of nickel, iron, or cobalt.

[0066] Figures 6–8B illustrate how the magnetoresistive tracks may be connected. Figure 6 shows a magnetic multi-turn sensor 4 similar to that described with reference to Figures 1–3, comprising multiple magnetoresistive tracks arranged in a spiral. An internal magnetoresistive track (corresponding to resistor R15) is connected to an external magnetoresistive track (corresponding to resistor R16) via a connecting magnetoresistive track (corresponding to resistor R1) that crosses the spiral via a trench and bridge arrangement 40, as described above. The spiral includes multiple metal contacts 42 along the spiral, which may be provided via the deposition of metallic material to define multiple magnetoresistive sensing elements R1–R16, and may be connected to a power supply to allow their resistances to be measured.

[0067] For example, as shown in Figure 7, the magnetoresistive elements R1 to R6 may be connected in a Wheatstone bridge configuration. Alternatively, as shown in Figures 8A and 8B, the magnetoresistive elements R1 to R6 may be connected in a matrix configuration, and the lines indicated by 80 represent the path of the spiral itself, as described in more detail in German Patent Application Publication DE102017104551A1 and U.S. Patent Application Publication 2017 / 261345, the contents of which are incorporated herein by reference in their entirety.

[0068] Purpose

[0069] Any of the principles and advantages discussed herein can be applied to other systems, not just those described above. Some embodiments may include a subset of the features and / or advantages described herein. Further embodiments can be provided by combining elements and operations of the various embodiments described above. The actions of the methods described herein may be performed in any order as necessary. Furthermore, the actions of the methods described herein may be performed sequentially or in parallel as necessary. While the circuits are shown in a specific configuration, other equivalent configurations are possible.

[0070] Any of the principles and benefits discussed herein can be implemented in connection with any other system, apparatus, or method that can benefit from any of the teachings herein. For example, any of the principles and benefits described herein can be implemented in connection with any device that has a need to correct rotational angular position data originating from a rotating magnetic field. Furthermore, the device may include any magnetoresistive or Hall effect device that can sense a magnetic field.

[0071] Aspects of this disclosure can be implemented in various electronic devices or systems. For example, phase correction methods and sensors implemented according to any of the principles and advantages described herein may be included in various electronic devices and / or various applications. Examples of electronic devices and applications include, but are not limited to, servos, robotics, aircraft, submarines, toothbrushes, biomedical sensing devices, and parts of consumer electronic products such as semiconductor dies and / or package modules and electronic test equipment. Electronic devices may include unfinished products, including those for industrial, automotive, and / or medical applications.

[0072] Unless the context explicitly requires otherwise, words such as “comprising,” “including,” and “comprising” throughout the description and claims should be interpreted in a comprehensive, not exclusive or exhaustive, sense, meaning “including, but not limited to.” As commonly used herein, the words “joining” or “connecting” refer to two or more elements that can be connected directly or via one or more intermediate elements. Thus, while the various schematic diagrams shown in the figures depict exemplary arrangements of elements and components, additional intervening elements, devices, features, or components may be present in actual embodiments (assuming that the functionality of the depicted circuit is not adversely affected). As used herein, the word “based on” is generally intended to encompass “based solely on” and “based at least partially on.” In conjunction with this, as used in this application, the words “in this specification,” “above,” “below,” and words of similar meaning refer to the entire application and not to any particular part thereof. Where the context allows, words in forms for carrying out the invention that use the singular or plural form may also include the plural or singular form, respectively. The word “or” referring to a list of two or more items is intended to encompass all interpretations of the following word, namely any item in the list, all items in the list, and any combination of items in the list. All numerical values ​​or distances provided herein are intended to include similar values ​​within the error of measurement.

[0073] While specific embodiments have been described, these embodiments are presented merely as examples and are not intended to limit the scope of this disclosure. In fact, the novel apparatus, systems, and methods described herein can be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications can be made to the forms of methods and systems described herein without departing from the spirit of this disclosure. [Explanation of symbols]

[0074] 1. Multi-turn sensor 2 sensors 10 circuit boards 11 Substrate surface 12 Trench 13A, 13B lamps 14 Bridge 15 Side view 16 magnetoresistive tracks 17 Outer spiral winding 18 Connecting Magnetic Resistance Tracks 19. Inner spiral winding 20 circuit boards 22 Trench 24 Bridge 25 magnetoresistive tracks 28 Connecting Magnetic Resistance Tracks 40 Bridge configuration 42 Metal contacts 52 Bridge 54, 56 Spiral winding 58 magnetoresistive track 200 silicon wafers 202 Intermediate layer, oxide layer 204 Mask Layer 206 Photoresist layer 208 Trench 210 Bridge 900 wafers 902 Oxide layer 904 Mask layer 906 Resist 908 patterns 910 Trench 912 Bridge 1000 transparent substrates 1002 Photoresist Material 1004 Magnetoresistive materials 1100 wafers 1102 Oxide layer 1104 Masking layer 1106 Trench 1108 Bridge 1200 wafers 1204 Bridge 1206 Trench 1208 Membrane 1304 Bridge 1308 Truck 1402 Trench 1404 Bridge 1406 Connecting Track 1408 Trucks 1500 circuit boards 1502 Trench 1504 Bridge 1508 Magnetoresistive Track

Claims

1. It is a magnetic multi-rotation sensor, Multiple magnetoresistive elements connected in series and arranged in a continuous spiral configuration, A substrate including at least a wafer layer on which the plurality of magnetoresistive elements are formed, It is configured to receive at least one magnetoresistive element, and its bottom and sides are trenches containing the wafer layer, A magnetic multi-turn sensor comprising: a substrate having at least one bridge formed on the trench, the at least one bridge being formed from a portion of the wafer layer and configured to support at least one magnetoresistive element; and

2. The magnetic multi-turn sensor according to claim 1, wherein the trench is configured to receive a plurality of magnetoresistive elements defining one side of the continuous spiral configuration, and the substrate comprises a bridge configured to receive a magnetoresistive element connecting the inner loop and the outer loop of the continuous spiral configuration.

3. The magnetic multi-turn sensor according to claim 1, wherein the trench is configured to receive one magnetoresistive element connecting the inner loop and the outer loop of the continuous spiral configuration, and the substrate comprises the at least one bridge formed on the trench to receive a plurality of magnetoresistive elements defining one side of the continuous spiral configuration.

4. The magnetic multi-turn sensor according to claim 1, wherein the substrate comprises a plurality of bridges formed on the trench to receive a plurality of magnetoresistive elements defining one side of the continuous spiral configuration, and each bridge receives one magnetoresistive element.

5. The magnetic multi-turn sensor according to any one of claims 1 to 4, wherein the plurality of magnetoresistive elements are one of giant magnetoresistance (GMR) elements or tunnel magnetoresistance (TMR) elements.

6. A method for manufacturing a closed-loop magnetic multi-turn sensor, Forming a substrate comprising a wafer, an intermediate layer, and a mask layer, Etching the regions of the mask layer and the intermediate layer in order to form trenches in the substrate, wherein one or more portions of the mask layer are preserved so as to form at least one bridge on the trenches. In order to form a continuous spiral of magnetoresistive elements, a magnetoresistive film is deposited on the substrate, and the magnetoresistive film is etched to form the magnetoresistive elements, wherein at least one magnetoresistive element is formed in the trench. A method comprising the following: the at least one magnetoresistive element is formed on the at least one bridge.

7. The method according to claim 6, wherein a plurality of magnetoresistive elements are formed in the trench to define one side of the spiral, and the at least one magnetoresistive element formed on the at least one bridge connects the inner loop and the outer loop of the spiral.

8. The method according to claim 6, wherein a plurality of magnetoresistive elements are formed on the at least one bridge to define one side of the spiral, and the at least one magnetoresistive element formed in the trench connects the inner loop and the outer loop of the spiral.

9. The method according to claim 6, further comprising etching the regions of the mask layer and the intermediate layer to form ramps in the mask layer and the intermediate layer at each end of the trench.

10. The method according to claim 6, wherein etching the regions of the mask layer and the intermediate layer includes lithographic etching.

11. The method according to claim 6, wherein the deposition of the magnetoresistive film is performed using a tilt and rotation deposition system.

12. The method according to claim 6, wherein ion beam etching or angled reactive ion (RIE) etching is used to form the at least one magnetoresistive element in the trench.

13. The method according to claim 6, wherein the intermediate layer comprises one of an oxide layer, a nitride layer, and an oxynitride layer.

14. The method according to claim 6, wherein the mask layer comprises an episilicon layer.

15. The method according to claim 6, wherein the mask layer comprises a hard mask layer for selective etching.

16. The method according to claim 15, wherein a selective etching solution is applied to etch the region of the intermediate layer beneath the region of the hard mask layer.

17. The method according to claim 16, wherein the selective etching solution comprises one of potassium hydroxide (KOH), ethylenediamine pyrocatechol (EDP), or tetramethylammonium hydroxide (TMAH).

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