Strain gauge and strain measurement assembly
A strain gauge includes a resistor formed of a doped silicon material, a conductive shield, and an isolation element disposed between the resistor and the conductive shield. The isolation element electrically isolates the resistor from the conductive shield.
1. A strain gauge, comprising:
a resistor formed of a doped silicon material;
a conductive shield; and
an isolation element disposed between the resistor and the conductive shield and electrically isolating the resistor from the conductive shield, the resistor and the isolation element are formed within a single silicon substrate.
2. The strain gauge of claim 1 , wherein the resistor is a p-type doped section of the silicon substrate.
3. The strain gauge of claim 2 , wherein the isolation element is an n-type doped section of the silicon substrate forming a p-n junction with the p-type doped section.
4. The strain gauge of claim 3 , wherein the conductive shield is formed within the single silicon substrate.
5. The strain gauge of claim 4 , wherein the conductive shield is an n+-type highly doped section of the silicon substrate.
6. The strain gauge of claim 3 , wherein the conductive shield is a metal layer on which the silicon substrate is disposed.
7. The strain gauge of claim 3 , wherein the isolation element surrounds a lower side and a plurality of lateral sides of the resistor.
8. The strain gauge of claim 7 , further comprising a guard ring formed within the single silicon substrate.
9. The strain gauge of claim 8 , wherein the guard ring is an n+-type highly doped section of the silicon substrate section disposed at a same height as the resistor along a height direction and spaced apart from the lateral sides of the resistor in a lateral direction perpendicular to the height direction.
10. The strain gauge of claim 1 , wherein the resistor is a p-type doped silicon layer and the isolation element is an oxide on which the p-type doped silicon layer is disposed.
11. The strain gauge of claim 10 , wherein the conductive shield is an n+-type highly doped silicon substrate on which the oxide is disposed.
12. The strain gauge of claim 10 , wherein the conductive shield is a metal layer on which the oxide is disposed.
13. The strain gauge of claim 1 , wherein the isolation element includes a first isolation element disposed on a lower side of the resistor and a second isolation element disposed on an upper side of the resistor opposite the lower side.
14. The strain gauge of claim 13 , wherein the conductive shield includes a first conductive shield disposed on a side of the first isolation element opposite the resistor and a second conductive shield disposed on a side of the second isolation element opposite the resistor.
15. The strain gauge of claim 13 , further comprising a contact pad electrically connected to the resistor and extending through the second isolation element.
16. The strain gauge of claim 14 , further comprising a passivation layer positioned over the second conductive shield.
17. A strain measurement assembly, comprising:
a force responsive member;
a strain gauge including a resistor formed of a doped silicon material, a conductive shield, and an isolation element disposed between the resistor and the conductive shield and electrically isolating the resistor from the conductive shield, the isolation element includes a first isolation element disposed on a lower side of the resistor and a second isolation element disposed on an upper side of the resistor opposite the lower side, the conductive shield includes a first conductive shield disposed on a side of the first isolation element opposite the resistor and a second conductive shield disposed on a side of the second isolation element opposite the resistor; and
an attachment material attaching the strain gauge to the force responsive member.
18. A strain gauge, comprising:
a resistor formed of a doped silicon material;
a conductive shield;
an isolation element disposed between the resistor and the conductive shield and electrically isolating the resistor from the conductive shield, the isolation element includes a first isolation element disposed on a lower side of the resistor and a second isolation element disposed on an upper side of the resistor opposite the lower side; and
a contact pad electrically connected to the resistor and extending through the second isolation element.