A method for bias control of a discrete injection based hall device

Abstract

The application discloses a Hall device bias control method based on discrete injection, which can effectively improve current sensitivity. The Hall device comprises a first bias port and a second bias port, and the method comprises the following steps: disconnecting the first bias port and the second bias port of the Hall device in an electrical manner, and injecting constant currents into the first bias port and the second bias port respectively.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more specifically, to a bias control method for Hall devices based on discrete injection. Background Technology

[0002] Vertical Hall devices face a significant reverse Hall potential problem. The magnetic field induces a large reverse Hall potential at the PN junction surface at the bottom and edges of the device, thereby reducing the Hall potential at the top surface. This characteristic is detrimental to improving the current sensitivity of vertical Hall devices.

[0003] Horizontal Hall effect devices face severe short-circuit effects. Conventional methods to suppress short-circuit effects include shortening the branch width of the shallow N-well and the electrode length. However, the electrode length cannot be shortened indefinitely, and shortening the electrode length easily leads to an increase in the device offset voltage. Deep Trench Isolation (DTI) layers in SOI-BCD (Silicon on Isolation Bipolar-CMOS-BCD) technology can be used to effectively suppress short-circuit effects in horizontal Hall effect devices. However, DTI is incompatible with some BCD processes. Horizontal Hall effect devices are conventionally biased in current-mode or voltage-mode, with equipotential bias electrodes. This characteristic is detrimental to improving the sensitivity of horizontal Hall effect devices. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a bias control method for Hall devices based on discrete injection to improve current sensitivity.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A bias control method for a Hall device based on discrete injection, wherein the Hall device includes a first bias port and a second bias port, the method comprising: electrically disconnecting the first bias port and the second bias port of the Hall device, and injecting a constant current into the first bias port and the second bias port respectively.

[0006] As a preferred example, two current sources are provided: one current source injects a constant current into the first bias port, and the other current source injects a constant current into the second bias port.

[0007] As a preferred example, the constant current injected into the first bias port is equal to the constant current injected into the second bias port.

[0008] As a preferred example, the Hall device is a vertical Hall device; the vertical Hall device includes: a substrate, a P-type epitaxial layer formed on the substrate, a deep N-well layer formed on the P-type epitaxial layer, a shallow trench isolation structure formed on the upper surface of the Hall device, and five electrode ports arranged in sequence: a first bias port, a second port, a third port, a fourth port, and a second bias port; the third port is grounded, and the second and fourth ports are used as Hall voltage output terminals.

[0009] As a preferred example, the doping concentration of the deep N-well layer is lower than... The width is 3μm and the depth is greater than 3μm; the distance from the second port and the fourth port to the third port is 2μm; the distance from the first bias port and the second bias port to the third port is greater than 5μm and less than 11μm.

[0010] As a preferred example, both the first bias port and the second bias port are biased with a current of 100μA. Under the condition that the magnetic field changes from 0 to 0.1T, the change in current flowing through the first bias port and the second bias port is less than 50nA.

[0011] As a preferred example, the Hall device is a horizontal Hall device; the horizontal Hall device includes: a substrate, a P-type epitaxial layer formed on the substrate, a shallow N-well layer formed in the P-type epitaxial layer, a high-energy P-well layer for isolating paired electrode ports, a P+ barrier layer located in the center of the shallow N-well layer, and eight electrode ports arranged in pairs and sequentially around the shallow N-well layer: a first bias port and a second bias port, a fifth port and a sixth port, a seventh port and an eighth port, and a ninth port and a tenth port; the seventh port and the eighth port are opposite to the first bias port and the second bias port; the seventh port and the eighth port are electrically connected and grounded, and the fifth port and the ninth port are used as Hall voltage output terminals.

[0012] As a preferred example, the doping concentration of the shallow N-well layer is: The depth of the high-energy P-well layer is 1 μm; the depth of the high-energy P-well layer is greater than 1.5 μm, and the depth of the P+ barrier layer is 0.2 μm.

[0013] As a preferred example, under the bias condition of a total current of 50μA injected into the first bias port and the second bias port, and under the condition that the magnetic field changes from 0 to 0.1T, the current change value does not exceed 50nA.

[0014] As a preferred example, a high-energy P-well layer is used to electrically isolate the paired electrode ports, so that the first bias port and the second bias port have different potentials when a magnetic field bias is applied.

[0015] Compared with existing technologies, the present invention provides a Hall device bias control method based on discrete injection, which can improve current sensitivity. The Hall device includes a first bias port and a second bias port. The method includes: electrically disconnecting the first bias port and the second bias port of the Hall device, and injecting a constant current into the first bias port and the second bias port respectively. By disconnecting the first bias port and the second bias port and injecting the same current into each, the present invention suppresses changes in the current of the first bias port and the second bias port due to the influence of a magnetic field. The present invention can break the equipotential characteristics of the bias electrodes of the Hall device, effectively improving the current sensitivity of the Hall device. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the relevant technologies and the accompanying drawings used in the embodiments will be briefly introduced below.

[0017] Figure 1 This is a structural diagram of the vertical Hall device in Embodiment 1 of the present invention.

[0018] Figure 2 This is a top view of the vertical Hall effect device in Embodiment 1 of the present invention.

[0019] Figure 3 This is a Hall potential distribution diagram of the vertical Hall device under combined injection conditions in Embodiment 1 of the present invention.

[0020] Figure 4 These are Hall potential distribution diagrams for combined injection and discrete injection of the vertical Hall device in Embodiment 1 of the present invention; wherein Figure (a) is for combined injection and Figure (b) is for discrete injection.

[0021] Figure 5 This is a Hall potential distribution diagram showing that the injected currents at the two bias ports are different during discrete injection in Embodiment 1 of the present invention.

[0022] Figure 6 This is a schematic diagram of the structure of the horizontal Hall device in Embodiment 2 of the present invention.

[0023] Figure 7 Figure 1 shows the effect of short-circuit effect on sensitivity of existing horizontal Hall devices. Figure 2(a) shows the device structure and doping concentration distribution, and Figure 3(b) shows the effect of short-circuit effect on Hall potential.

[0024] Figure 8 This is a schematic diagram comparing the Hall potential of a horizontal Hall device under combined injection and discrete injection conditions; where Figure (a) shows combined injection, Figure (b) shows discrete injection, Figure (c) shows the Hall potential distribution under combined injection conditions, and Figure (d) shows the Hall potential distribution under discrete injection conditions.

[0025] The diagram shows: First bias port 1, Second port 2, Third port 3, Fourth port 4, Second bias port 5, Fifth port 6, Sixth port 7, Seventh port 8, Eighth port 9, Ninth port 10, and Tenth port 11. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0027] This invention discloses a bias control method for a Hall effect device based on discrete injection. The Hall effect device includes a first bias port and a second bias port. The method includes: electrically disconnecting the first bias port and the second bias port of the Hall effect device, and injecting a constant current into the first bias port and the second bias port respectively. Preferably, two current sources are provided: one current source injects a constant current into the first bias port, and the other current source injects a constant current into the second bias port.

[0028] In the method described above, constant currents are injected separately into the first bias port and the second bias port. Existing technology uses the same current source to simultaneously inject current into both the first and second bias ports; this technique is called combined injection. In combined injection, the first and second bias ports are actually connected to the same conductor, resulting in the same potential. This causes the current to deflect under the influence of a magnetic field, leading to a slight change in the injected current at both bias ports (theoretically, the currents at both ports are the same when there is no magnetic field; however, even a slight change in current has a significant impact on the Hall potential, causing a significant reverse Hall potential). This embodiment uses discrete injection, which effectively eliminates these slight current changes, ensuring that the currents at both ports remain the same under the influence of a magnetic field bias, thus improving current sensitivity.

[0029] Preferably, the constant current injected into the first bias port is equal to the constant current injected into the second bias port. Injecting equal constant currents into the first and second bias ports eliminates the misalignment of the two Hall output ports caused by unequal currents.

[0030] Example 1

[0031] The Hall effect device is a vertical Hall effect device. For example... Figure 1 and Figure 2As shown, the vertical Hall device includes: a substrate, a P-type epitaxial layer formed on the substrate, a deep N-well layer formed on the P-type epitaxial layer, a shallow trench isolation structure (STI) formed on the upper surface of the Hall device, and five electrode ports arranged sequentially: a first bias port 1, a second port 2, a third port 3, a fourth port 4, and a second bias port 5. The third port 3 is grounded, and the second port 2 and the fourth port 4 are used as Hall voltage output terminals.

[0032] Preferably, the doping concentration of the deep N-well layer is lower than that of the deep N-well layer. The width is 3μm and the depth is greater than 3μm. The lower the doping concentration, the smaller the width and the larger the well depth, which is beneficial to improving the current sensitivity of the vertical Hall device. However, the width cannot be too small, otherwise the device offset voltage will easily increase.

[0033] Preferably, the distances from the second port 2 and the fourth port 4 to the third port 3 are both 2 μm; the distances from the first bias port 1 and the second bias port 5 to the third port 3 are both greater than 5 μm and less than 11 μm. The second and fourth ports are set to 2 μm because the Hall potential change is greatest at this location.

[0034] Preferably, under the condition that both the first bias port 1 and the second bias port 5 are biased with a current of 100μA, and the magnetic field changes from 0 to 0.1T, the change in current I flowing through the first bias port 1 and the second bias port 5 is... hall Less than 50nA (at this point, there is a slight difference in potential between the first bias port 1 and the second bias port 5, varying by 1.4mV and -1.4mV respectively from a bias voltage of 700mV). (The influence of reverse Hall potential on I...) hall The magnitude is directly proportional. If it exceeds this value, it means that the current source has not effectively suppressed the small current deflection caused by the magnetic field, affecting the elimination effect of the reverse Hall potential.

[0035] When using the method of the present invention, a constant current is injected into the first bias port 1 using a current source, a constant current is injected into the second bias port 5 using another current source, the third port 3 is grounded, and the second port 2 and the fourth port 4 are used as Hall voltage output terminals.

[0036] For the Hall device of Embodiment 1 described above, bias control is performed using the method of this invention and existing methods. The doping concentration of the deep N-well layer of the vertical Hall device is... The width is 3μm and the depth is 3.3μm. The distance from the second port 2 and the fourth port 4 to the third port 3 is 2μm; the distance from the first bias port 1 and the second bias port 5 to the third port 3 is 8μm. All electrodes are 0.4μm wide and 2μm long.

[0037] Using the discrete injection method of this invention, the vertical Hall device maintains the width of the deep N-well layer (DNW) at 3 μm by reducing the well region width. Furthermore, the shallow trench isolation structure (STI) depth is optimized to 0.4 μm, forcing the bias current to flow deeper into the well region to improve the carrier response to the magnetic field.

[0038] The existing method involves using a current source to inject a combined total current of 200 μA into the first bias port 1 and the second bias port 5 of a vertical Hall effect device, where the first bias port 1 and the second bias port 5 are connected to the same electrode. Figure 3 As shown.

[0039] The Hall device of Example 1 is biased and controlled using the method of the present invention.

[0040] The above offset process was simulated using Sentaurus TCAD software. Figure 3 It can be seen that under the combined injection condition, the potentials of the first bias port 1 and the second bias port 5 remain the same. Under the influence of the magnetic field, the injected current is deflected, resulting in a reverse Hall potential at the PN junction surface at the bottom of the device. Furthermore, the outflow currents I1 and I5 from the first bias port 1 and the second bias port 5 are not strictly the same; the difference is reflected in I... hall Its expression is:

[0041]

[0042] Figure 3 (a) shows the doping concentration distribution of the vertical Hall device. Figure 3 (b) shows the potential distribution of a vertical Hall device under combined injection conditions. The Hall potential is the change in internal potential of the device after a magnetic field bias is applied. Figure 3 In this process, a large reverse Hall potential is generated at the edge of the device's ground electrode and the bottom of the PN junction. A large reverse Hall potential is generated at the bottom PN junction surface of the device, meaning that an opposite potential change occurs at the bottom of the device, resulting in a decrease in the actual readable Hall potential change on the upper surface. Under the influence of the magnetic field, the currents at the first bias port 1 and the second bias port 5 are no longer the same, exhibiting a slight difference I. hall .

[0043] from Figure 4 (a) It can be seen that under the condition of combined injection, a huge reverse Hall potential is generated at the bottom of the vertical Hall device, resulting in a decrease in the effective output Hall potential on the upper surface. Wherein, I hall is 130 nA.

[0044] from Figure 4(b) It can be seen that under discrete injection, the reverse Hall potential at the bottom is greatly suppressed, and the sensitivity is increased by about 15%.

[0045] contrast Figure 4 (a) and Figure 4 (b) It can be seen that the discrete injection method of the present invention can effectively improve the output potential of the Hall electrode, that is, improve the sensitivity of the Hall device.

[0046] from Figure 4 (b) It can be seen that the currents at the first bias port 1 and the second bias port 5 remain constant and equal (i.e., I0). hall The term is zero, and it is unaffected by the magnetic field, thus eliminating the root cause of the reverse Hall potential. Regardless of whether there is an N-type buried layer inside the device, this method can effectively improve current sensitivity, and is especially suitable for simplified vertical Hall device structures without buried layers.

[0047] It is important to note that the key to eliminating the reverse Hall potential is to keep the injected current at the first bias port and the second bias port constant, not that the two ports are strictly the same.

[0048] Using the method of the present invention, current is injected into the first bias port 1 and the second bias port 5 of the vertical Hall device in Embodiment 1 through independent current sources, but the magnitudes of the currents are slightly different. For example... Figure 5 As shown in (a), a current of 99 μA is injected into the first bias port 1, and a current of 101 μA is injected into the second bias port 5. Figure 5 As shown in (b), a current of 101 μA is injected into the first bias port 1, and a current of 99 μA is injected into the second bias port 5. Although the magnitudes of the currents injected into the first bias port 1 and the second bias port 5 are slightly different, the injected currents are not affected by the magnetic field. Figure 5 (a) and Figure 5 (b) It can be seen that the slightly different current magnitudes injected into the first bias port 1 and the second bias port 5 (e.g., nanoampere differences due to current source mismatch) will not affect the elimination of the reverse Hall potential, but may introduce additional offset voltage. In practical applications, the current source matching accuracy should be controlled as much as possible. Figure 5 As shown, when the injection current deviation is within a certain range, the discrete injection method of the present invention can still maintain a sensitivity superior to that of combined injection.

[0049] Example 2 The Hall effect device is a horizontal type. For example... Figure 6As shown, the horizontal Hall device includes: a substrate, a P-type epitaxial layer formed on the substrate, a shallow N-well layer formed in the P-type epitaxial layer, a high-energy P-well layer (PX) for isolating paired electrode ports, a P+ barrier layer located in the center of the shallow N-well layer, and eight electrode ports arranged in pairs and sequentially around the shallow N-well layer: a first bias port 1 and a second bias port 5, a fifth port 6 and a sixth port 7, a seventh port 8 and an eighth port 9, a ninth port 10 and a tenth port 11. The seventh port 8 and the eighth port 9 are opposite to the first bias port 1 and the second bias port 5; the seventh port 8 and the eighth port 9 are electrically connected and grounded, and the fifth port 6 and the ninth port 10 are used as Hall voltage output terminals.

[0050] Preferably, the doping concentration of the shallow N-well layer is [value missing]. The depth of the shallow N-well layer is 1 μm; the depth of the high-energy P-well layer is greater than 1.5 μm, and the depth of the P+ barrier layer is 0.2 μm. The shallow N-well layer has a relatively shallow depth and a lower doping concentration, which is beneficial to improving current sensitivity. The depth of the high-energy P-well layer is greater than that of the shallow N-well layer to ensure electrical isolation between the electrodes.

[0051] Preferably, under the bias condition that the first bias port 1 and the second bias port 5 are injected with a total current of 50μA, and the magnetic field changes from 0 to 0.1T, the current change value does not exceed 50nA.

[0052] Preferably, a high-energy P-well layer is used to electrically isolate the paired electrode ports, so that the first bias port 1 and the second bias port 5 have different potentials when a magnetic field bias is applied.

[0053] For the horizontal Hall effect device of Example 2, bias control is performed using the method of this invention and existing methods. All electrode port lengths L C The length of the shallow N-well layer is 4 μm; the length L of the shallow N-well layer is 40 μm, and the width W is 28 μm; the intercalation length L of the high-energy P-well layer (PX) is 4 μm. T 10μm, interpolation width W T It is 1μm.

[0054] The biasing steps of this invention are as follows: First bias port 1 and second bias port 5 are electrically disconnected, and electrically isolated from each other through a high-energy P-well layer, ensuring that the potentials of first bias port 1 and second bias port 5 are different when a magnetic field bias is applied; seventh port 8 and eighth port 9 are electrically connected and grounded together; first bias port 1 is connected to a first current source, and second bias port 5 is connected to a second current source, with the two current sources operating independently. Both current sources are configured to output a constant DC current of 25 μA. Fifth port 6 and ninth port 10 are used as Hall voltage output terminals, and the Hall voltage between the two ports is measured under a 0.1T magnetic field condition.

[0055] Existing horizontal Hall effect devices only have four ports. The existing biasing method for horizontal Hall effect devices, namely combined injection, involves connecting the first bias port to a current source with a current of 50μA; grounding the port opposite to the first bias port; and using the remaining two ports as Hall voltage output terminals, measuring the Hall voltage between the two ports under a 0.1T magnetic field condition.

[0056] The above biasing process was simulated using the Sentaurus TCAD software. Figure 7 This diagram illustrates the effect of short-circuit effect on the sensitivity of an existing horizontal Hall effect device. (a) shows the device structure and doping concentration distribution, and (b) shows the effect of short-circuit effect on the Hall potential. A current of 50 μA is injected into the first bias port, and the port opposite to the first bias port is grounded; the other two ports are used as Hall voltage output terminals. Under a 0.1T magnetic field bias, the potential change of the Hall electrode is 70%~80% of its maximum value. Figure 7 It can be seen that a significant short-circuit effect occurs near the Hall electrode.

[0057] Figure 8 (a) is a schematic diagram of a horizontal Hall effect device using existing combined injection. In the diagram, the first bias port 1 and the second bias port 5 are shorted to the same current source. Under the action of a magnetic field, the injected current of the first bias port 1 and the second bias port 5 undergoes a slight change. Wherein I hall It is 135nA.

[0058] Figure 8 (b) is a schematic diagram of the discrete injection of the horizontal Hall device using the present invention. In the figure, the first bias port 1 and the second bias port 5 are connected to different current sources respectively. Under the action of the magnetic field, the injection current of the first bias port 1 and the second bias port 5 remains strictly unchanged.

[0059] Figure 8 (c) is the Hall potential distribution diagram of a horizontal Hall device under combined injection conditions. Figure 8 (d) is the Hall potential distribution diagram of a horizontal Hall device under discrete injection conditions.

[0060] from Figure 8 (c) and Figure 8 (d) It can be seen that the discrete injection method of the present invention produces a larger potential change in the horizontal Hall device compared to the existing combined injection method. Under the conditions of a 0.1T magnetic field and a 50μA bias current, the injection current change between the first bias port 1 and the second bias port 5 does not exceed 0.05μA. This indicates that the discrete injection method of the present invention effectively suppresses the modulation effect of the magnetic field on the injection current. Compared with the existing combined injection method, the method of the present invention significantly improves the Hall voltage output and effectively suppresses the short-circuit effect.

[0061] Compared to existing horizontal Hall effect device biasing methods, this invention breaks the equipotential characteristics of the bias electrode through discrete injection, and combined with a high-energy P-well layer isolation structure, effectively suppresses short-circuit effects and improves the current sensitivity of the device. This method is compatible with existing BCD processes, does not require the introduction of a DTI layer, and has good process versatility.

[0062] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A bias control method for Hall effect devices based on discrete injection, characterized in that, The Hall device includes a first bias port and a second bias port. The method includes: electrically disconnecting the first bias port and the second bias port of the Hall device, and injecting a constant current into the first bias port and the second bias port respectively.

2. The bias control method for Hall devices based on discrete injection according to claim 1, characterized in that, Two current sources are set up: one current source injects a constant current into the first bias port, and the other current source injects a constant current into the second bias port.

3. The Hall device bias control method based on discrete injection according to claim 1, characterized in that, The constant current injected into the first bias port is equal to the constant current injected into the second bias port.

4. The Hall device bias control method based on discrete injection according to claim 1, characterized in that, The Hall device is a vertical Hall device; the vertical Hall device includes: a substrate, a P-type epitaxial layer formed on the substrate, a deep N-well layer formed on the P-type epitaxial layer, a shallow trench isolation structure formed on the upper surface of the Hall device, and five electrode ports arranged in sequence: a first bias port (1), a second port (2), a third port (3), a fourth port (4), and a second bias port (5); the third port (3) is grounded, and the second port (2) and the fourth port (4) are used as Hall voltage output terminals.

5. The Hall device bias control method based on discrete injection according to claim 4, characterized in that, The doping concentration of the deep N-well layer is lower than The width is 3μm and the depth is greater than 3μm; the distance from the second port (2) and the fourth port (4) to the third port (3) is 2μm; the distance from the first bias port (1) and the second bias port (5) to the third port (3) is greater than 5μm and less than 11μm.

6. The Hall device bias control method based on discrete injection according to claim 4, characterized in that, Both the first bias port (1) and the second bias port (5) are biased with a current of 100μA. Under the condition that the magnetic field changes from 0 to 0.1T, the change in current flowing through the first bias port (1) and the second bias port (5) is less than 50nA.

7. The Hall device bias control method based on discrete injection according to claim 1, characterized in that, The Hall device is a horizontal Hall device; the horizontal Hall device includes: a substrate, a P-type epitaxial layer formed on the substrate, a shallow N-well layer formed in the P-type epitaxial layer, a high-energy P-well layer for isolating paired electrode ports, a P+ barrier layer located in the center of the shallow N-well layer, and eight electrode ports arranged in pairs and sequentially arranged around the shallow N-well layer: a first bias port (1) and a second bias port (5), a fifth port (6) and a sixth port (7), a seventh port (8) and an eighth port (9), a ninth port (10) and a tenth port (11); the seventh port (8) and the eighth port (9) are opposite to the first bias port (1) and the second bias port (5); the seventh port (8) and the eighth port (9) are electrically connected and grounded, and the fifth port (6) and the ninth port (10) are used as Hall voltage output terminals.

8. The Hall device bias control method based on discrete injection according to claim 7, characterized in that, The doping concentration of the shallow N-well layer is: The depth of the high-energy P-well layer is 1 μm; the depth of the high-energy P-well layer is greater than 1.5 μm, and the depth of the P+ barrier layer is 0.2 μm.

9. The Hall device bias control method based on discrete injection according to claim 7, characterized in that, Under the bias condition that the first bias port (1) and the second bias port (5) inject a total current of 50μA, the current change value does not exceed 50nA when the magnetic field changes from 0 to 0.1T.

10. The Hall device bias control method based on discrete injection according to claim 7, characterized in that, The paired electrode ports are electrically isolated by using a high-energy P-well layer, so that the potentials of the first bias port (1) and the second bias port (5) are different when a magnetic field bias is applied.

Images