Sealed capacitive sensor for physical measurements
View Patent ↗A capacitive-type sensor comprises a glass plate having an electrode formed thereon, and a micromachined structure formed from a semiconductor material and having an insulating rim formed thereon. A conducting seal is formed on the insulating rim and arranged to be bonded to the glass substrate to define an enclosed cavity containing the electrode, to thereby define a capacitive element, the conducting seal being arranged, in use, to have an electrical signal passed there through to determine a capacitance thereof which is indicative of the parameter to be determined by the sensor.
1. A capacitive-type sensor comprising:
a glass structure having an electrode thereon;
a micromachined structure formed from a semiconductor material and having an insulating rim formed thereon; and
a conducting seal formed on the insulating rim and arranged to be bonded to the glass structure to define an enclosed cavity containing the electrode, to thereby define a capacitive element, the conducting seal being arranged to have an electrical signal passed there through to determine a capacitance thereof which is indicative of a parameter to be determined by the sensor, wherein the conducting seal surrounds the cavity.
2. The sensor according to claim 1 , wherein the micromachined structure includes a diaphragm.
3. The sensor according to claim 2 , wherein an electrical connector is provided to the diaphragm.
4. The sensor according to claim 3 , wherein the electrical connector for the diaphragm is provided by the semiconductor material.
5. The sensor according to claim 2 , wherein the diaphragm includes a stiff center boss.
6. The capacitive sensor of claim 2 , wherein the conducting seal surrounds the diaphragm.
7. The sensor according to claim 1 , wherein the semiconductor material is silicon.
8. The sensor according to claim 1 , wherein the semiconductor material comprises a rigid support rim.
9. The sensor according to claim 1 , wherein the conducting seal between the glass structure and the semiconductor material is provided by anodic bonding.
10. The sensor according to claim 1 , wherein additional press contacts are provided external to the enclosed cavity to allow for interaction with other devices.
11. The sensor according to claim 1 , wherein the electrode is shaped such that, during manufacture of the sensor, a size of the electrode is adjustable to control the capacitance of the electrode.
12. The sensor according to claim 1 , wherein the sensor is arranged to be a pressure sensor.
13. The sensor according to claim 1 , wherein the sensor is arranged to be an accelerometer.
14. The sensor according to claim 1 , wherein the conducting seal is electrically connected to the electrode on the glass structure.
15. The sensor according to claim 1 , wherein the conducting seal is connected to an electrical bond pad outside the enclosed cavity.
16. A capacitive sensor comprising:
a glass structure having an electrode thereon;
a micromachined structure formed from a semiconductor material;
an insulating rim formed on the micromachined structure; and
a conductive seal ring formed on the insulating rim that bonds the glass structure such that it defines an enclosed cavity containing the electrode, thereby defining a capacitive element;
wherein an electrical signal passes through the conducting seal to determine a capacitance of the seal ring, and wherein the capacitance is indicative of a parameter to be determined by the sensor, and
wherein the conductive seal ring surrounds the cavity.
17. The sensor according to claim 16 , wherein the micromachined structure includes a diaphragm, and the conductive seal ring surrounds the diaphragm.
18. A capacitive sensor comprising:
a glass structure having an electrode thereon;
a micromachined structure formed from a semiconductor material and including a diaphragm;
an insulating rim formed on the micromachined structure; and
a conductive seal ring formed on the insulating rim that bonds the glass structure such that it defines an enclosed cavity containing the electrode, thereby defining a capacitive element,
wherein an electrical signal passes through the conducting seal to determine a capacitance of the seal ring, the capacitance is indicative of a parameter to be determined by the sensor, and the conductive seal ring surrounds the diaphragm.