Hall effect device with trench about a micron or greater in depth
In one aspect, a Hall effect device includes an implantation layer; an epitaxial layer located above the implantation layer; a trench filled with a dielectric material and extending from a top surface of the epitaxial layer into the implantation layer and defining an enclosed region; a buried layer the epitaxial layer from the implantation layer within the enclosed region; and a contact pad located on the epitaxial layer. The trench reduces a current from the contact pad from traveling in a lateral direction orthogonal to a vertical direction and enables the current to travel in the vertical direction.
1 . A Hall effect device, comprising:
an implantation layer;
an epitaxial layer having a first portion and a second portion, wherein the implantation layer is below the first portion of the epitaxial layer;
a trench filled with a dielectric material and extending from a top surface of the epitaxial layer into the implantation layer, the trench in contact with the second portion of the epitaxial layer, wherein the trench defines an enclosed region;
wherein the first portion of the epitaxial layer and the implantation layer are surrounded by the trench within the enclosed region, and wherein the first and second portions of the epitaxial layer are on opposite sides of the trench, wherein the Hall effect device comprises vertical Hall elements outside of the enclosed region and the trench and a planar Hall element in the enclosed region,
a well layer abutting the implantation layer in the enclosed region and abutting the second portion of the epitaxial layer for the vertical Hall elements, wherein the trench extends into the well layer;
a substrate under the well layer;
a contact pad located on the epitaxial layer; and
wherein a current bias on the contact pad generates a current that flows into the first portion of the epitaxial layer and into the implantation layer,
wherein the current moves in a vertical direction through the second portion of the epitaxial layer, and
wherein the trench reduces the current from traveling in a lateral direction orthogonal to the vertical direction and enables the current to travel in the vertical direction.
2 . The Hall effect device of claim 1 , wherein a top surface of the device has the planar Hall effect element.
3 . The Hall effect device of claim 1 , wherein the trench forms four sides of a square.
4 . The Hall effect device of claim 3 , wherein the vertical Hall elements comprise four vertical Hall effect elements,
wherein each vertical Hall effect element is located on a corresponding one side of the square.
5 . The Hall effect device of claim 1 , wherein the trench forms a circle.
6 . The Hall effect device of claim 1 , wherein the trench is more than a micron in depth.
7 . The Hall effect device of claim 6 , wherein the trench is more than 10 microns in depth.
8 . The Hall effect device of claim 7 , wherein the trench is more than 20 microns in depth.
9 . The Hall effect device of claim 1 , wherein the trench is a first trench,
wherein the dielectric material is a first dielectric material;
further comprising a second trench filled with a second dielectric material and extending from the epitaxial layer into the well layer, the second trench being in contact with the second portion of the epitaxial layer opposite the first trench,
wherein the second trench reduces the current from traveling in the lateral direction and enables the current to travel in the vertical direction.
10 . The Hall effect device of claim 9 , wherein the first dielectric material and the second dielectric material comprise the same material.
11 . The Hall effect device of claim 9 , wherein the implantation layer has a second-type dopant, and
wherein the epitaxial layer has the second-type dopant.
12 . The Hall effect device of claim 11 , wherein the first-type dopant is a p-type dopant, and
wherein the second-type dopant is an n-type dopant.
13 . The Hall effect device of claim 11 , wherein the first-type dopant is a n-type dopant, and
wherein the second-type dopant is an p-type dopant.
14 . The Hall effect device of claim 9 , wherein the second trench is more than a micron in depth.
15 . The Hall effect device of claim 14 , wherein the second trench is more than 10 microns in depth.
16 . The Hall effect device of claim 15 , wherein the second trench is more than 20 microns in depth.
17 . The Hall effect device of claim 1 , wherein the implantation layer has a second-type dopant, and
wherein the epitaxial layer has the second-type dopant.
18 . The Hall effect device of claim 17 , wherein the first-type dopant is a p-type dopant, and
wherein the second-type dopant is an n-type dopant.
19 . The Hall effect device of claim 17 , wherein the first-type dopant is a n-type dopant, and
wherein the second-type dopant is an p-type dopant.
20 . The Hall effect device of claim 1 , wherein the epitaxial layer is about 8.5 microns in depth.
21 . The Hall effect device of claim 1 , wherein the epitaxial layer is more doped than the implantation layer is doped.
22 . The Hall effect device of claim 1 , further comprising:
wherein the vertical Hall elements comprises four vertical Hall effect elements;
wherein the planar Hall effect element is on the top surface of the device; and
wherein the trench separates the four vertical Hall effect elements from the planar Hall effect element;
wherein the trench forms four sides of a square, and
wherein each vertical Hall effect element is located on a corresponding one side of the square.
23 . The Hall effect device of claim 22 , wherein each vertical Hall effect element includes at least three contact pads.
24 . The Hall effect device of claim 1 , wherein the dielectric material comprises silicon dioxide and/or polysilicon.
25 . The Hall effect device of claim 1 , wherein the substrate has a first-type dopant,
wherein the implantation layer is located in the substrate.
26 . The Hall effect device of claim 25 , wherein the first-type dopant is a p-type dopant, and
wherein the second-type dopant is an n-type dopant.
27 . The Hall effect device of claim 25 , wherein the first-type dopant is a n-type dopant, and
wherein the second-type dopant is an p-type dopant.
28 . The Hall effect device of claim 1 , further including STI regions between the vertical Hall elements and respective doped areas implanted in the first portion of the epitaxial layer in contact with the STI regions, wherein the doped areas are doped with a type that is opposite of the dopant type of the first portion of the epitaxial layer.