PRESSURE SENSOR AND WIRE GUIDE ASSEMBLY
A pressure sensor chip is described. The pressure sensor chip include a substrate, a polycrystalline silicon layer, at least one silicon layer, and a diaphragm movement element. The polycrystalline silicon layer is formed on the substrate and has a cavity recess formed therein. The at least one silicon layer is formed on the polycrystalline silicon layer and covers the cavity recess thereby forming a reference chamber with a diaphragm. The diaphragm movement element is configured to sense movement of the diaphragm. An assembly incorporating the pressure sensor chip and a method of forming the pressure sensor chip are also described.
1 . A pressure sensor chip comprising:
a substrate;
a polycrystalline silicon layer formed on the substrate and having a cavity recess formed therein;
at least one silicon layer formed on the polycrystalline silicon layer and covering the cavity recess thereby forming a reference chamber with a diaphragm; and
a diaphragm movement element configured to sense movement of the diaphragm.
2 . The sensor chip of claim 1 , wherein the cavity recess is formed so as to expose the substrate.
3 . The sensor of claim 2 , wherein the substrate has an etch stop layer as a top surface, and the cavity recess is formed so as to expose the etch stop layer.
4 . The sensor chip of claim 1 , wherein the substrate is a semiconductor substrate.
5 . The sensor chip of claim 4 , wherein the substrate is a silicon substrate.
6 . The sensor chip of claim 1 , wherein the diaphragm movement element comprises at least one of a piezoresistive element, a capacitor, or a mechanically resonating sensor.
7 . The sensor chip of claim 1 , wherein the diaphragm movement element comprises at least a piezoresistive layer formed over the silicon layer.
8 . The sensor chip of claim 1 , wherein the sensor chip is an absolute pressure sensor.
9 . The sensor chip of claim 1 , wherein the sensor is a differential pressure sensor.
10 . The sensor chip of claim 1 , wherein the substrate is suitable for processing in silicon standard planar processing.
11 . A pressure sensor comprising:
the sensor chip of claim 1 , wherein the diaphragm movement element comprises:
a piezoresistive element; and
a temperature sensitive resistor.
12 . The sensor of claim 11 , wherein the piezoresistive element is part of a first Wheatstone bridge of a sensor circuit, and the temperature sensitive resistor is part of a second Wheatstone bridge of the sensor circuit.
13 . The sensor of claim 11 , wherein the diaphragm movement element comprises a piezoresistive element formed over the diaphragm, the sensor further comprising:
a group of resistors, the piezoresistive element and the group of resistors in combination forming a Wheatstone bridge.
14 . A pressure sensor and guide wire assembly comprising:
a sensor chip comprising:
a substrate;
a polycrystalline silicon layer formed on the substrate and having a cavity recess formed therein;
at least one silicon layer formed on the polycrystalline silicon layer and covering the cavity recess thereby forming a reference chamber with a diaphragm; and
a diaphragm movement element configured to sense movement of the diaphragm;
a wire; and
a mount, wherein the sensor chip is mounted to the wire via the mount.
15 . The assembly of claim 14 , wherein the cavity recess is formed so as to expose the substrate.
16 . The assembly of claim 15 , wherein the substrate has an etch stop layer as a top surface, and the cavity recess is formed so as to expose the etch stop layer.
17 . The assembly of claim 14 , further comprising electrical leads connected to the pressure sensor.
18 . The assembly of claim 14 , further comprising a flexible coil.
19 . The assembly of claim 14 , further comprising a tube surrounding at least a portion of the wire.
20 . The assembly of claim 14 , wherein the diaphragm movement element comprises:
a piezoresistive element; and
a temperature sensitive resistor.
21 . The assembly of claim 14 , wherein the diaphragm movement element comprises a piezoresistive element formed over the diaphragm; the assembly further comprising:
a group of resistors, the piezoresistive element and the group of resistors in combination forming a Wheatstone bridge.
22 . A method of forming a pressure sensor chip, comprising:
providing a substrate;
forming a polycrystalline silicon layer on the substrate;
forming a cavity recess in the polycrystalline silicon layer;
bonding at least one silicon layer to the polycrystalline silicon layer to cover the cavity recess thereby forming a reference chamber with a diaphragm; and
forming a diaphragm movement element configured to sense movement of the diaphragm.
23 . The method of claim 22 , wherein the forming a cavity recess comprises forming a cavity recess to expose the substrate.
24 . The method of claim 22 , wherein providing the substrate comprises providing the substrate with an etch stop layer as a top surface, and wherein the forming the cavity recess comprises forming the cavity recess to expose the etch stop layer.
25 . The method of claim 22 , wherein the forming a cavity recess comprises etching the polycrystalline silicon layer.
26 . The method of claim 25 , wherein the forming a cavity recess comprises dry etching the polycrystalline silicon layer.
27 . The method of claim 25 , wherein the forming a cavity recess comprises wet etching the polycrystalline silicon layer.
28 . The method of claim 22 , wherein the forming a diaphragm movement element comprises forming at least one of a piezoresistive element, a capacitor, or a mechanically resonating sensor.
29 . The method of claim 22 , wherein the forming a diaphragm movement element comprises forming a piezoresistive element over the diaphragm.