Hall element

Abstract

The utility model discloses a Hall element. The Hall element comprises a substrate and a cross-shaped functional layer arranged on the substrate. A Hall plane is formed on the top surface of the cross-shaped functional layer; the side wall of the cross-shaped functional layer is obliquely arranged and forms an included angle smaller than 90 degrees with the surface of the substrate; four end parts of the cross-shaped functional layer are respectively provided with a contact electrode, and the contact electrodes cover the top surfaces and three side walls of the end parts; wherein the edge side wall, located on the top surface, of the contact electrode is obliquely arranged, and an included angle smaller than 90 degrees is formed between the contact electrode and the top surface, so that the contact electrode better wraps a Hall plane etching step, the contact area is increased, the contact characteristic is improved, the unbalanced voltage is reduced, and the sensing capability of the device is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of semiconductor devices, and in particular relates to a Hall element. Background Art

[0002] The Hall element is a magnetic sensor based on the Hall effect. The Hall effect refers to the physical phenomenon that when a magnetic field acts on carriers in metal conductors and semiconductors, the carriers are deflected, and an additional electric field is generated perpendicular to the direction of the current and the magnetic field, thereby generating a lateral potential difference at both ends of the semiconductor. The Hall device made according to the Hall effect can use the magnetic field as the working medium to convert the motion parameters of an object into a voltage output, so that it has the functions of sensing and switching.

[0003] In the absence of an external magnetic field, the Hall voltage of an ideal Hall element is 0. Due to the asymmetric structure of the device due to reasons such as material growth / process / graphic design, a voltage will be generated after the device is powered on even without an external magnetic field. This voltage is called unbalanced voltage or offset voltage. The existence of unbalanced voltage will cause the actual Hall output voltage to deviate from the true value, thereby affecting the accuracy of the Hall element and limiting its application. Utility Model Content

[0004] The utility model aims at the deficiencies in the prior art and provides a Hall element.

[0005] In order to achieve the above objectives, the technical solution of the utility model is:

[0006] A Hall element comprises a substrate and a cross-shaped functional layer arranged on the substrate; the top surface of the cross-shaped functional layer forms a Hall plane; the side walls of the cross-shaped functional layer are arranged obliquely and form an angle less than 90° with the surface of the substrate; contact electrodes are respectively arranged at the four ends of the cross-shaped functional layer, and the contact electrodes cover the top surface and three side walls of the end; wherein the edge side walls of the contact electrodes located on the top surface are arranged obliquely and form an angle less than 90° with the top surface.

[0007] Optionally, the edges of the cross-shaped functional layer at the cross-intersection corners are rounded.

[0008] Optionally, the sidewall of the cross-shaped functional layer forms an angle of 30° to 50° with the surface of the substrate.

[0009] Optionally, the edge sidewall of the contact electrode located on the top surface forms an angle of 30° to 50° with the top surface.

[0010] Optionally, the edge sidewall of the contact electrode located on the top surface extends along the width direction of the cross-shaped functional layer and covers a width range.

[0011] Optionally, the contact electrode extends from covering the three side walls to covering the substrate surface outside the three side walls.

[0012] Optionally, the projection of the contact electrode on the substrate surface is a pentagon formed by a square with missing corners, wherein the edges of the missing corners form edge side walls located on the top surface, and the edges of the missing corners are arranged along the width direction of the cross-shaped functional layer.

[0013] Optionally, the width of the cross-shaped functional layer is greater than 10 μm.

[0014] Optionally, it further includes a passivation layer and a lead-out metal, wherein the passivation layer covers the cross-shaped functional layer and the contact electrode, the passivation layer has an opening above the contact electrode, and the lead-out metal contacts the contact electrode through the opening.

[0015] Optionally, the Hall element is a GaAs-based Hall element. The substrate is a semi-insulating GaAs substrate, and the cross-shaped functional layer is an n-GaAs layer.

[0016] Optionally, the contact electrode is a stack of Au / Ge / Ni / Au / Ti, forming an ohmic contact with the functional layer.

[0017] Optionally, the lead-out metal also serves as a heat dissipation metal layer, and the material is Au. The lead-out metal is located within the range of the contact layer.

[0018] The beneficial effects of the utility model are:

[0019] By tilting the side walls of the cross-shaped functional layer and the contact electrode, and the contact electrode covering the top surface and three side walls of the end of the cross-shaped functional layer, the contact electrode can better cover the Hall plane etching step, increase the contact area, and improve the contact characteristics; and by the rounded corner design at the edge of the cross-intersection corner, the generation of asymmetric factors can be reduced; thereby, the unbalanced voltage can be reduced and the sensing capability of the device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a top view of the structure of a Hall element of an embodiment;

[0021] Figure 2 is a schematic diagram of the three-dimensional structure of a cross functional layer and a contact electrode of a Hall element of an embodiment;

[0022] Figure 3 for Figure 2 Schematic diagram of the top view of the positional relationship between the cross-shaped functional layer and the contact electrode;

[0023] Figure 4 for Figure 1 Cross-sectional view along the a-a' direction;

[0024] Figure 5 for Figure 4 A partial enlarged schematic diagram in which angles are marked;

[0025] Figure 6 for Figure 1 Cross-sectional view along the b-b' direction. DETAILED DESCRIPTION

[0026] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. The drawings of the present invention are only for illustration to make it easier to understand the present invention, and the specific proportions can be adjusted according to design requirements. The upper and lower relationships of the relative elements and the definitions of the front and back sides in the figures described in the text should be understood by those skilled in the art to refer to the relative positions of the components, so they can all be flipped to present the same components, which should all fall within the scope disclosed in this specification.

[0027] refer to Figures 1 to 6 The Hall element of the embodiment includes a substrate 1 and a cross-shaped functional layer 2 disposed on the substrate 1; the top surface 2a of the cross-shaped functional layer 2 forms a Hall plane; the side wall 2b of the cross-shaped functional layer 2 is tilted and forms an angle less than 90° with the surface of the substrate 1; the four ends of the cross-shaped functional layer 2 are respectively provided with contact electrodes 3, and the contact electrodes 3 cover the top surface 2a and three side walls 2b of the end; wherein the edge side wall 3a of the contact electrode 3 located on the top surface 2a is tilted and forms an angle less than 90° with the top surface 2a. The surface of the cross-shaped functional layer 2 and the contact electrode 3 is covered with a passivation layer 4, and the passivation layer 4 has an opening 41 on the contact electrode 3, and the lead-out metal 5 is in contact with and connected to the contact electrode 3 through the opening 41.

[0028] The Hall element can be a GaAs-based Hall element, the substrate 1 is a semi-insulating GaAs substrate, and the cross-shaped functional layer 2 is an n-GaAs layer. The cross shape mentioned here refers to a cross shape projected on the substrate surface, and the cross width D>10μm. The edges of the cross-shaped cross corners are rounded corners 2c. The setting of the rounded corners 2c improves the current crowding effect generated by the traditional right-angle corners and improves the symmetry of the current distribution. All side walls 2b of the cross-shaped functional layer 2 are tilted, and preferably form an angle α of 30° to 50° with the surface of the substrate 1, such as 35°, 40°, 45° and any value therebetween. Reduce the step etching angle, the side wall 2b is tilted to form a slope, on the one hand, increase the contact area between the contact electrode 3 and the cross-shaped functional layer 2, improve the contact characteristics, and thus reduce the unbalanced voltage; on the other hand, it is convenient for the metal adhesion coating (climbing gold) of the contact electrode 3, and the depth of the contact electrode 3 after tempering can cover the Hall plane etching step, reduce the asymmetric factor, and optimize the current path.

[0029] The contact electrode 3 is a stack of Au / Ge / Ni / Au / Ti, and forms an ohmic contact with the cross-shaped functional layer 2. The edge sidewall 3a of the contact electrode 3 located on the top surface 2a extends along the width D direction of the cross-shaped functional layer 2 and covers the width range, and extends from the three-sided sidewall 2b covered to the surface of the substrate 1 outside the three-sided sidewall 2b covered, that is, the remaining edge sidewalls are located on the substrate 1. The three-sided sidewalls mentioned here refer to the end sidewalls of the end (that is, the end of the cross extension direction) and the sidewalls on the left and right sides. The three-sided coating reduces the asymmetric factors introduced by the side creeping gold, optimizes the current path, and improves the contact characteristics.

[0030] For example, the projection of the contact electrode 3 on the substrate surface is a pentagon formed by the missing corners of the square, wherein the side of the missing corner forms an edge side wall 3a located on the top surface 2a, which is arranged along the width D direction of the cross-shaped functional layer 2, that is, perpendicular to the length direction (cross extension direction). The length of the edge side wall 3a is not less than the width D, and there is no corner on the Hall plane, which improves the current crowding effect that may be caused by the corner and improves the symmetry of the current distribution. The other three corners of the square (i.e., the three right angles of the pentagon) are respectively located on the outside of the three side walls 2b, thereby wrapping part of the length of the end of the cross-shaped functional layer 2. The above-mentioned structural arrangement can achieve contact with the largest possible area, increase the contact area and improve the contact characteristics.

[0031] The edge sidewall 3a of the contact electrode 3 located on the top surface 2a is tilted, and preferably forms an angle β of 30° to 50° with the top surface 2a, such as 35°, 40°, 45° and any value therebetween. The tilted arrangement improves the contact characteristics, reduces the generation of asymmetric factors, and reduces the unbalanced voltage. The other edge sidewalls of the contact electrode 3 may also be tilted.

[0032] The passivation layer 4 is made of SiN or SiOx, and is used for passivation and protection of the epitaxial layer and the metal layer. Conventionally, the contact electrode 3 is made of Au, and is used for wiring / heat dissipation. It is located within the contact layer and is smaller in size than the contact layer.

[0033] When manufacturing the above-mentioned Hall element, a functional layer is first formed on a substrate using an epitaxial deposition process, the functional layer is etched to form a cross-shaped Hall plane, an inclined side surface is formed by adjusting the step etching angle, and then metal is deposited at the end and ohmic contact is formed by tempering.

[0034] It can be understood that the contact characteristics are improved through the setting of the above-mentioned structure. After testing, the value of the contact characteristic characterization parameter (i.e., the contact resistance between the metal and the functional layer) is positively correlated with the value of the unbalanced voltage. The smaller the value of the contact characteristic characterization parameter, the better the contact characteristics. By improving the contact characteristics, the unbalanced voltage can be reduced and the sensing ability of the device can be improved.

[0035]

[0036] The above embodiments are only used to further illustrate a Hall element of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the protection scope of the technical solution of the present invention.

Claims

1. A Hall element, characterized in that: It comprises a substrate and a cross-shaped functional layer arranged on the substrate; the top surface of the cross-shaped functional layer forms a Hall plane; the side walls of the cross-shaped functional layer are arranged obliquely and form an angle less than 90° with the surface of the substrate; the four ends of the cross-shaped functional layer are respectively provided with contact electrodes, and the contact electrodes cover the top surface and three side walls of the ends; wherein the edge side walls of the contact electrodes located on the top surface are arranged obliquely and form an angle less than 90° with the top surface.

2. The Hall element according to claim 1, characterized in that: The edges of the cross-shaped functional layer at the cross-intersection corners are rounded.

3. The Hall element according to claim 1, characterized in that: The side wall of the cross-shaped functional layer forms an angle of 30° to 50° with the surface of the substrate.

4. The Hall element according to claim 1, characterized in that: The edge sidewall of the contact electrode located on the top surface forms an angle of 30° to 50° with the top surface.

5. The Hall element according to claim 1, characterized in that: The edge sidewall of the contact electrode located on the top surface extends along the width direction of the cross-shaped functional layer and covers the width range.

6. The Hall element according to claim 1, characterized in that: The contact electrode extends from covering the three side walls to covering the substrate surface outside the three side walls.

7. The Hall element according to claim 1, characterized in that: The projection of the contact electrode on the substrate surface is a pentagon formed by a square with missing corners, wherein the edges of the missing corners form edge side walls located on the top surface, and the edges of the missing corners are arranged along the width direction of the cross-shaped functional layer.

8. The Hall element according to claim 1, characterized in that: The width of the cross-shaped functional layer is greater than 10 μm.

9. The Hall element according to claim 1, characterized in that: It also includes a passivation layer and a lead-out metal, wherein the passivation layer covers the cross-shaped functional layer and the contact electrode, the passivation layer has an opening above the contact electrode, and the lead-out metal contacts the contact electrode through the opening.

10. The Hall element according to claim 1, characterized in that: The Hall element is a GaAs-based Hall element.

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