Vertical hall element

Abstract

To provide a vertical hall element capable of adjusting magnetic detection sensitivity.SOLUTION: A vertical hall element 100 has a P-type semiconductor substrate 10, an N-type epitaxial layer 30 formed on the surface of the P-type semiconductor substrate 10, an electrode group 110, arranged on the surface of N-type epitaxial layer 30, with electrodes 111 to 115 arranged in a straight line, a constant current source that supplies a constant current between electrodes 111 to 115 in electrode group 110, and a conductor 120 arranged such that at least part of a current path overlaps with that of the constant current when viewed in plan, and to which a predetermined voltage can be applied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vertical Hall element. [Background technology]

[0002] Hall elements can be easily formed on the surface of a semiconductor substrate and are used in a variety of applications because they are capable of detecting position and angle as magnetic sensors without contact. Among Hall elements, horizontal Hall elements that detect magnetic field components perpendicular to the surface of a semiconductor substrate are generally well known, but various vertical Hall elements that detect magnetic field components parallel to the surface of a semiconductor substrate have also been proposed.

[0003] For example, a vertical Hall element has been proposed in which a conductive plate fixed at a predetermined potential covers the surface of the element, thereby maintaining high detection accuracy as a Hall element and increasing the noise resistance of the Hall element (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-128400 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of one aspect of the present invention is to provide a vertical Hall element capable of adjusting magnetic detection sensitivity. [Means for solving the problem]

[0006] The vertical Hall element according to one embodiment of the present invention comprises: a semiconductor substrate of a first conductivity type; a second conductivity type impurity diffusion layer formed on the surface of the semiconductor substrate; an electrode group, which is disposed on the surface of the impurity diffusion layer and which includes three or more electrodes arranged in a line; a constant current source that applies a constant current between the electrodes in the electrode group; a conductor that is arranged to overlap at least a part of the current path of the constant current when viewed in a plane, and to which a predetermined voltage can be applied; It has. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide a vertical Hall element capable of adjusting magnetic detection sensitivity. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a plan view of a vertical Hall element according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing a cross section of a vertical Hall element according to the first embodiment of the present invention. [Figure 3] FIG. 3 is an explanatory diagram showing a cross section of a vertical Hall element according to the first embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram showing a plan view of a vertical Hall element according to a second embodiment of the present invention. [Figure 5] FIG. 5 is an explanatory diagram showing a cross section of a vertical Hall element according to a second embodiment of the present invention. [Figure 6] FIG. 6 is an explanatory diagram showing a plan view of a vertical Hall element according to a third embodiment of the present invention. [Figure 7] FIG. 7 is an explanatory diagram showing a cross section of a vertical Hall element according to a third embodiment of the present invention. [Figure 8] FIG. 8 is an explanatory diagram showing a cross section of a vertical Hall element according to a fourth embodiment of the present invention. [Figure 9] FIG. 9 is an explanatory diagram showing a cross section of a vertical Hall element according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, identical components are denoted by the same reference numerals, and redundant explanations may be omitted. In the drawings, the X, Y, and Z directions are perpendicular to one another. The direction including the X direction and the opposite direction of the X direction (-X direction) is referred to as the "X-axis direction," the direction including the Y direction and the opposite direction of the Y direction (-Y direction) is referred to as the "Y-axis direction," and the direction including the Z direction and the opposite direction of the Z direction (-Z direction, depth direction) is referred to as the "Z-axis direction" (height direction, thickness direction). In this regard, in the following embodiments, the surface of each film facing the Z direction may be referred to as the "surface." The drawings are schematic, and the ratios of width, length, and depth are not as shown in the drawings. In the following description, the first conductivity type is defined as P type, and the second conductivity type is defined as N type.

[0010] (First embodiment) Fig. 1 is an explanatory diagram showing a plan view of a vertical Hall element according to a first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1, showing the cross section of the vertical Hall element according to the first embodiment of the present invention. Fig. 3 is a schematic cross-sectional view taken along line III-III in Fig. 1, showing the cross section of the vertical Hall element according to the first embodiment of the present invention. The vertical Hall element 100 of this embodiment includes an electrode group 110, a P-type well layer 50 disposed on the outer periphery thereof, and a conductor 120 disposed above the electrode group 110.

[0011] The electrode group 110 is an electrode group that enables the vertical Hall element 100 to function as a magnetic sensor. The electrode group 110 is formed by five electrodes 111-115.

[0012] The electrodes 111 to 115 are arranged in a straight line on the surface of the N-type epitaxial layer 30, and are each formed in an N-type impurity region with a higher concentration than the N-type epitaxial layer 30. The electrodes 111 to 115 all have the same structure, are rectangular in plan view, and are arranged at equal intervals along the short side. As a result, the electrodes 111 to 115 have a highly symmetric structure, and can therefore reduce the output offset voltage even when no external magnetic field is applied.

[0013] Furthermore, the electrodes 111 to 115 are each connected to a voltage source or the like, and a required voltage is applied by turning on and off the switch elements connected to each of them. For example, as shown in FIG. 1, electrodes 111, 113, and 115 are drive current supply electrodes, and electrodes 112 and 114 are Hall voltage output electrodes. In this case, a constant current source CC is connected to the central electrode 113, and electrodes 111 and 115 are grounded. This causes a drive current Ih to flow in the +Y and −Y directions, respectively, and the current paths are as shown by the dotted arrows in FIG. 1. When an external magnetic field is applied in the +X direction to this drive current Ih, a Lorentz force is generated in the −Z direction for electrons of the drive current Ih in the +Y direction, and a Lorentz force is generated in the +Z direction for electrons of the drive current Ih in the −Y direction. This generates a Hall voltage with an opposite positive and negative potential difference. The vertical Hall element 100 outputs the voltage between electrodes 112 and 114 as a Hall voltage by adding the absolute values ​​of these potential differences, thereby enabling it to sensitively detect an external magnetic field applied from the +X direction.

[0014] When performing correction to remove the offset voltage using the spinning current method, the drive current supply electrode and the Hall voltage output electrode may be interchanged in order to obtain the required output voltage. The electrodes 114 and 115 are arranged to remove an offset voltage, and the three electrodes 111 to 113 are sufficient if the external magnetic field is simply to be detected.

[0015] 2 and 3, the vertical Hall element 100 is formed on the surface of a P-type semiconductor substrate 10, and includes an N-type buried layer 20, an N-type epitaxial layer 30 as an impurity diffusion layer, a P-type buried layer 40, a P-type well layer 50, and an insulating film 60. The vertical Hall element 100 further includes a conductor 120 and an interlayer insulating film 130.

[0016] The P-type semiconductor substrate 10 is a silicon wafer doped with P-type impurities.

[0017] The N-type buried layer 20 is formed near the boundary between the P-type semiconductor substrate 10 and the N-type epitaxial layer 30, and is disposed below the electrode group 110. The N-type buried layer 20 has a higher impurity concentration than the N-type epitaxial layer 30, and therefore has a lower resistance than the N-type epitaxial layer 30, making it easier for the driving current Ih to flow through it. Therefore, the current path of the driving current Ih may be such that it flows downward through the N-type epitaxial layer 30, passes through the N-type buried layer 20, and then flows upward through the N-type epitaxial layer 30, or it may flow throughout the entire N-type epitaxial layer 30 without passing through the N-type buried layer 20. Therefore, when operating as a magnetic sensor, the N-type buried layer 20 and the N-type epitaxial layer 30 become the current path of the driving current Ih and function as a magnetic sensing portion.

[0018] The N-type epitaxial layer 30 is provided on the P-type semiconductor substrate 10, and N-type impurities are implanted and diffused therein. Although the impurity concentration of the N-type epitaxial layer 30 is constant in this embodiment, it may be configured so that the impurity concentration increases with depth. This allows the current path to be widened in a balanced manner by providing an impurity concentration gradient such that the resistance value of the deepest current path is approximately the same as the resistance value of the current path passing through the shallower portion, thereby improving the magnetic detection sensitivity of the vertical Hall element 100.

[0019] The P-type buried layer 40 is formed near the boundary between the P-type semiconductor substrate 10 and the N-type epitaxial layer 30. The P-type buried layer 40 is disposed at a position separated from the N-type buried layer 20 and in contact with the bottom surface of the P-type well layer 50.

[0020] The P-type well layer 50 is formed for element isolation and is arranged in a rectangular ring shape on the periphery spaced apart from the electrode group 110 in a plan view. The P-type well layer 50 is formed deep so as to be in contact with the P-type buried layer 40, which will be described later. This electrically isolates the vertical Hall element 100 from other regions (not shown) on the P-type semiconductor substrate 10 around it. In the region on the P-type semiconductor substrate 10 electrically isolated from the vertical Hall element 100, elements such as transistors that form at least one of a circuit for processing an output signal from the vertical Hall element 100 and a circuit for supplying a signal to the vertical Hall element 100 are provided. Furthermore, since the P-type well layer 50 has a ring shape, it is possible to prevent the current from the electrode group 110 from diffusing, thereby improving the magnetic detection sensitivity and the accuracy of removing the offset voltage.

[0021] The insulating film 60 is a silicon oxide film formed by a LOCOS (Local Oxidation of Silicon) method on the surface of the N-type epitaxial layer 30. The insulating film 60 is provided around the electrode group 110 and on the upper surface of the P-type well layer 50. The insulating film 60 is preferably one having no conductivity type, since a depletion layer would be generated near the surface if it had a conductivity type such as a P-type electrode isolation diffusion layer.

[0022] The conductor 120 is a metal layer formed inside the interlayer insulating film 130 formed on the upper surfaces of the insulating film 60 and the electrode group 110 so as to cover the entire current path of the N-type epitaxial layer 30 and the N-type buried layer 20, which are surrounded by the P-type well layer 50. This conductor 120 is connected to a voltage source VS, and a "predetermined voltage" is applied to it.

[0023] If this "predetermined voltage" is a "negative voltage," an electric field E is applied to the N-type buried layer 20 and the N-type epitaxial layer 30, which form the current path of the drive current Ih, as indicated by the arrows in FIG. 2, decreasing the carrier density in the N-type buried layer 20 and the N-type epitaxial layer 30. As the carrier density decreases, the drive current Ih flows more slowly, and therefore the voltage applied to the electrode 113 from the constant current source CC, which keeps the amount of the drive current Ih constant, increases. As a result, the electrons of the drive current Ih, which now flow faster, are subjected to a larger Lorentz force due to the external magnetic field. This increases the magnetic detection sensitivity of the vertical Hall element 100.

[0024] On the other hand, if the "predetermined voltage" is a "positive voltage," an electric field E is applied to the N-type buried layer 20 and the N-type epitaxial layer 30 in the direction opposite to the arrow in FIG. 2, increasing the carrier density in the N-type buried layer 20 and the N-type epitaxial layer 30. As the carrier density increases, the driving current Ih flows more easily, and the voltage applied to the electrode 113 from the constant current source CC, which keeps the amount of driving current Ih constant, decreases. As a result, the Lorentz force of the external magnetic field on the electrons of the driving current Ih, which now flow more slowly, decreases. This reduces the magnetic detection sensitivity of the vertical Hall element 100.

[0025] This allows the vertical Hall element 100 to adjust the magnetic detection sensitivity depending on the sign and magnitude of the “predetermined voltage” applied to the conductor 120 . Furthermore, in the vertical Hall element 100, the conductor 120 is large enough to cover the entire current path when viewed from above, so that external noise entering from above can be blocked.

[0026] Although the conductor 120 is a metal layer in this embodiment, it may be a high-concentration impurity conductor made of polysilicon.

[0027] The interlayer insulating film 130 is formed over the entire upper surfaces of the insulating film 60 and the electrode group 110. In this embodiment, the interlayer insulating film 130 is a silicon oxide film doped with phosphorus and boron (sometimes referred to as a "BPSG (Boro-Phospho Silicate Glass) film").

[0028] Next, a method for manufacturing the vertical Hall element of this embodiment will be described. First, N-type impurities or P-type impurities are selectively implanted into regions of the P-type semiconductor substrate 10 where the N-type buried layer 20 and the P-type buried layer 40 are to be formed, and then an N-type epitaxial layer 30 containing N-type impurities is formed thereon. The P-type impurities are selectively implanted into the surface of the N-type epitaxial layer 30 and diffused to form a P-type well layer 50. Then, using an insulating film 60 formed on the surface of the N-type epitaxial layer 30 by the LOCOS method as a mask, N-type impurities are implanted to a high concentration from the surface of the N-type epitaxial layer 30 to form an electrode group 110. Next, after forming and planarizing the entire upper surfaces of the insulating film 60 and the electrode group 110, a metal layer conductor 120 is formed. The vertical Hall element 100 can be formed as described above.

[0029] As described above, the vertical Hall element 100 of this embodiment includes a constant current source CC that supplies a constant current between the electrodes 111 to 115, and a conductor 120 that is arranged to overlap at least a portion of the current path of the constant current when viewed in a plane, and to which a predetermined voltage can be applied.

[0030] As a result, when a negative voltage is applied to the conductor 120 of this vertical Hall element 100, an electric field E is applied as shown by the arrow in FIG. 2, reducing the carrier density in the current path and making it difficult for the drive current Ih to flow. This increases the voltage applied to the electrode 113 from the constant current source CC, and electrons in the drive current Ih, which now flow faster, are more susceptible to the Lorentz force due to the external magnetic field. Furthermore, because the electric field E is applied to the current path in the -Z direction, a Coulomb force in the +Z direction is applied to the electrons moving in the drive current Ih, causing the current path of the drive current Ih to disperse from the N-type buried layer 20 to the surface side of the N-type epitaxial layer 30, making them more susceptible to the Lorentz force due to the external magnetic field. This increases the magnetic detection sensitivity of the vertical Hall element 100.

[0031] On the other hand, when a positive voltage is applied to the conductor 120, an electric field E is applied in the direction opposite to the arrow in FIG. 2, increasing the carrier density in the current path and making it easier for the drive current Ih to flow. This reduces the voltage applied to the electrode 113 from the constant current source CC, and the electrons in the drive current Ih, which now flow more slowly, are less susceptible to the Lorentz force caused by the external magnetic field. Furthermore, because the electric field E is applied to the current path in the +Z direction, a Coulomb force in the -Z direction acts on the electrons moving in the drive current Ih, concentrating the current path of the drive current Ih toward the N-type buried layer, making it less susceptible to the Lorentz force caused by the external magnetic field. This reduces the magnetic detection sensitivity of the vertical Hall element 100.

[0032] This allows the vertical Hall element 100 to adjust the magnetic detection sensitivity depending on the sign and magnitude of the “predetermined voltage” applied to the conductor 120 .

[0033] (Second embodiment) Fig. 4 is an explanatory plan view of a vertical Hall element according to a second embodiment of the present invention, and Fig. 5 is a schematic cross-sectional view taken along line VV in Fig. 4, illustrating the cross section of the vertical Hall element according to the second embodiment of the present invention. As shown in FIGS. 4 and 5, the vertical Hall element 200 of this embodiment is similar to the vertical Hall element 100, except that the conductor 120 in the vertical Hall element 100 is changed to a conductor 140 having a narrower width. The conductor 140, which is a difference from the vertical Hall element 100, will be described below.

[0034] The conductor 140 is a metal layer formed above the electrode group 110 so as to cover part of the electrode group 110 inside the interlayer insulating film 130 formed on the upper surfaces of the insulating film 60 and the electrode group 110. Like the conductor 120, the conductor 140 is connected to a voltage source VS and has a "predetermined voltage" applied to it.

[0035] Even with the vertical Hall element 200 having such a structure, the magnetic detection sensitivity can be adjusted by adjusting the sign and magnitude of the “predetermined voltage” applied to the conductor 140, just like the vertical Hall element 100. The conductor 140 may also serve as a conductor for generating a bias magnetic field used for correction. In this case, in order to make the voltage distribution of the conductor 140 itself constant, a high-resistance resistor element is connected in the subsequent stage to pass a current through the conductor 140.

[0036] (Third embodiment) Fig. 6 is an explanatory plan view of a vertical Hall element according to a third embodiment of the present invention. Fig. 7 is a schematic cross-sectional view taken along line VII-VII in Fig. 6, illustrating the cross section of the vertical Hall element according to the third embodiment of the present invention. As shown in FIGS. 6 and 7, the vertical Hall element 300 of this embodiment is the same as the vertical Hall element 100, except that the conductor 120 in the vertical Hall element 100 is changed to a conductor 150 having the width of the electrodes 111 to 115 and further divided into three in the width direction. The conductor 150, which is a difference from the vertical Hall element 100, will be described below.

[0037] The conductor 150 is a metal layer that is wound in plan view inside the insulating film 60 and the interlayer insulating film 130 formed on the upper surfaces of the electrode group 110, and that is formed above the electrode group 110 so that a part of it covers the electrode group 110. One end of the wound conductor 150 is connected to a voltage source VS to apply a "predetermined voltage," and the other end is connected to a high-resistance resistor element to allow a current to flow through the conductor 150.

[0038] Even with the vertical Hall element 300 having such a structure, the magnetic detection sensitivity can be adjusted by adjusting the sign and magnitude of the "predetermined voltage" applied to the conductor 150, just like the vertical Hall element 100. In addition, since the conductor 150 is wound, it can generate a bias magnetic field more efficiently than the conductor 140.

[0039] (Fourth embodiment) FIG. 8 is an explanatory diagram showing a cross section of a vertical Hall element according to a fourth embodiment of the present invention. As shown in FIG. 8, the vertical Hall element 400 of this embodiment is similar to the vertical Hall element 100, except that a P-type buried layer 70 is arranged instead of the N-type buried layer 20 and the P-type buried layer 40 in the vertical Hall element 100, and the P-type buried layer 70 has the function of the conductor 120. The P-type buried layer 70, which is a difference from the vertical Hall element 100, will be described below.

[0040] The P-type buried layer 70 is formed near the boundary between the P-type semiconductor substrate 10 and the N-type epitaxial layer 30, and is disposed below the electrode group 110 so as to contact the lower surface of the P-type well layer 50. This P-type buried layer 70 is connected to a voltage source VS, and a "predetermined voltage" is applied to it. The "predetermined voltage" in the fourth embodiment is the same as the "predetermined voltage" in the first embodiment.

[0041] Even with the vertical Hall element 400 having such a structure, the magnetic detection sensitivity can be adjusted by adjusting the sign and magnitude of the “predetermined voltage” applied to the conductor 150, just like the vertical Hall element 100.

[0042] (Fifth embodiment) FIG. 9 is an explanatory diagram showing a cross section of a vertical Hall element according to a fifth embodiment of the present invention. As shown in FIG. 9, the vertical Hall element 500 of this embodiment is similar to the vertical Hall element 100, except that instead of an insulating film 60 being arranged above the N-type buried layer 20, multiple second conductors 80 are arranged. The second conductor 80, which is a difference from the vertical Hall element 100, will be described below.

[0043] The second conductor 80 is formed by forming a trench on the surface of the N-type epitaxial layer 30 and filling the trench with P-type polysilicon. The second conductor 80 is formed at least between the electrodes 111 to 115 in a plan view, but may also be configured to surround the entire electrodes 111 to 115. The second conductor 80 is This allows the vertical Hall element 500 to expand the depletion layer in the N-type epitaxial layer 30 in the direction from the trench side surface toward each electrode, thereby further widening the adjustment range of the sensitivity.

[0044] As described above, a vertical Hall element according to one embodiment of the present invention includes a semiconductor substrate of a first conductivity type, an impurity diffusion layer of a second conductivity type formed on the surface of the semiconductor substrate, and an electrode group on the surface of the impurity diffusion layer, the electrode group including three or more electrodes arranged in a line. The vertical Hall element also includes a constant current source for supplying a constant current between the electrodes of the electrode group, and a conductor to which a predetermined voltage can be applied, the conductor being arranged so as to overlap at least a part of the current path of the constant current in a plan view. This allows the vertical Hall element to adjust its magnetic detection sensitivity depending on the sign and magnitude of the "predetermined voltage" applied to the conductor.

[0045] Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0046] For example, although the first conductivity type has been described as P type and the second conductivity type as N type, the conductivity types may be reversed so that the first conductivity type is N type and the second conductivity type is P type.

[0047] Although the above-described embodiments have been described with reference to five electrodes in the electrode group, the number of electrodes is not limited to five. For example, if the offset voltage can be reduced or tolerated to such an extent that removal of the offset voltage by the spinning current method is unnecessary, a total of three electrodes, including two drive current supply electrodes and one Hall voltage output electrode, may be sufficient. In other words, by eliminating the electrodes 114 and 115 of the vertical Hall element 100 shown in FIG. 1 and other figures, the layout area can be reduced, thereby enabling the vertical Hall element to be miniaturized.

[0048] Furthermore, in each of the above embodiments, from the viewpoint of ease of manufacturing, the electrode group is formed of an N-type impurity region having a higher concentration than the N-type epitaxial layer, but the present invention is not limited to this. The electrodes may be made of polysilicon with a high concentration of P-type impurities. If the electrodes are made of P-type polysilicon, the difference in work function between the P-type polysilicon and the N-type epitaxial layer will be utilized to deplete the N-type epitaxial layer, which is advantageous in that it will increase sensitivity. [Explanation of symbols]

[0049] 10 P-type semiconductor substrate (first conductivity type semiconductor substrate) 20 N-type buried layer 30 N-type epitaxial layer (second conductivity type impurity diffusion layer) 40, 70 P-type buried layer 50 P-type well layer (first conductivity type well layer) 60 insulating film 80 Conductor (Second Conductor) 100, 200, 300, 400 Vertical Hall element 110 electrode group 111, 112, 113, 114, 115 electrode 120, 140, 150 conductor (first conductor) 130 Interlayer insulating film 170 Oxide film CC constant current source VS voltage source

Claims

1. a semiconductor substrate of a first conductivity type; a second conductivity type impurity diffusion layer formed on the surface of the semiconductor substrate; an electrode group, which is disposed on a surface of the impurity diffusion layer and which includes three or more electrodes arranged in a line; a constant current source that applies a constant current between the electrodes in the electrode group; a first conductor that is arranged to overlap at least a portion of the current path of the constant current when viewed from above, and to which a predetermined voltage can be applied; A vertical Hall element comprising:

2. 2. The vertical Hall element according to claim 1, wherein the first conductor is disposed above the electrode group.

3. 3. The vertical Hall element according to claim 2, wherein the first conductor is a metal layer or a high-concentration impurity conductor made of polysilicon.

4. 2. The vertical Hall element according to claim 1, wherein the first conductor is a buried layer of a first conductivity type disposed below the electrode group.

5. 2. The vertical Hall element according to claim 1, further comprising a second conductor formed of polysilicon of the first conductivity type, the second conductor being arranged so as to overlap at least a part of a current path of the constant current when viewed in cross section.

6. The first conductivity type is P-type, and the second conductivity type is N-type, 6. The vertical Hall element according to claim 1, wherein the electrode group is formed of a P-type highly doped polysilicon conductor.

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