Thermally compensated silicon pressure sensor
First Claim
1. A thermally compensated silicon pressure sensor comprising:
- (a) a single crystal of silicon including;
(1) a diaphragm portion with a top surface and a bottom surface, having a thickness permitting flexure when a pressure differential is applied between said top surface and said bottom surface and having a continuous loop resistor element disposed adjacent to said top surface in a position for exhibiting piezoresistivity when said diaphragm is flexed, a first resistor disposed in a central portion of said diaphragm portion, a second resistor connected to said first resistor and disposed in a peripheral portion of said diaphragm portion, a third resistor connected to said second resistor and disposed in a central portion of said diaphragm portion and a fourth resistor connected to said first and third resistors and disposed in a peripheral portion of said diaphragm portion; and
(2) a clamp ring portion disposed around the entire perimeter of said diaphragm portion having a thickness providing mechanical support to said diaphragm portion and permitting virtually no flexure of said clamp ring portion when a pressure differential is applied between said top surface and said bottom surface of said diaphragm portion, and further having a temperature sensitive resistor disposed therein;
(b) a first set of electrical terminals including a first electrical terminal disposed in ohmic contact with said continuous loop resistor element at the connection between said first and second resistors, a second electrical terminal in ohmic contact with said continuous loop resistor element at the connection between said second and third resistors, a third electrical terminal in ohmic contact with said continuous loop resistor element at the connection between said third and fourth resistors and a fourth electrical terminal disposed in ohmic contact with said continuous loop resistor element at the connection between said first and fourth resistors; and
(c) a second set of electrical terminals disposed in ohmic contact with said temperature sensitive resistor. PG,24
0 Assignments
0 Petitions
Accused Products
Abstract
A semiconductor pressure sensor employing the piezoresistive effect of single crystal silicon resistors to measure the flexure of a semiconductor diaphragm. In the preferred embodiment, a Wheatstone bridge composed of a first pair of resistors disposed on the center of the diaphragm and a second pair of resistors disposed on the periphery of the diaphragm is employed. Due to the nature of the diaphragm flexure, the first and second pairs of resistors exhibit piezoresistivity in opposite directions enabling pressure measurement with greater sensitivity. The diaphragm is mounted on and supported by a silicon clamp ring. The diaphragm and the clamp ring together form a unitary semiconductor structure. Because the piezoresistive effect which serves as a measure of the diaphragm flexure and hence as a measure of the pressure difference across the diaphragm is temperature dependent, the sensor also includes a temperature sensitive resistor, forming a part of the same unitary semiconductor structure, which provides a measure of the temperature of the piezoresistive elements. This measure of temperature enables external circuitry to correct for the temperature dependence of the piezoresistive effect thereby providing a pressure measurement of greater accuracy.
-
Citations
10 Claims
-
1. A thermally compensated silicon pressure sensor comprising:
-
(a) a single crystal of silicon including; (1) a diaphragm portion with a top surface and a bottom surface, having a thickness permitting flexure when a pressure differential is applied between said top surface and said bottom surface and having a continuous loop resistor element disposed adjacent to said top surface in a position for exhibiting piezoresistivity when said diaphragm is flexed, a first resistor disposed in a central portion of said diaphragm portion, a second resistor connected to said first resistor and disposed in a peripheral portion of said diaphragm portion, a third resistor connected to said second resistor and disposed in a central portion of said diaphragm portion and a fourth resistor connected to said first and third resistors and disposed in a peripheral portion of said diaphragm portion; and (2) a clamp ring portion disposed around the entire perimeter of said diaphragm portion having a thickness providing mechanical support to said diaphragm portion and permitting virtually no flexure of said clamp ring portion when a pressure differential is applied between said top surface and said bottom surface of said diaphragm portion, and further having a temperature sensitive resistor disposed therein; (b) a first set of electrical terminals including a first electrical terminal disposed in ohmic contact with said continuous loop resistor element at the connection between said first and second resistors, a second electrical terminal in ohmic contact with said continuous loop resistor element at the connection between said second and third resistors, a third electrical terminal in ohmic contact with said continuous loop resistor element at the connection between said third and fourth resistors and a fourth electrical terminal disposed in ohmic contact with said continuous loop resistor element at the connection between said first and fourth resistors; and (c) a second set of electrical terminals disposed in ohmic contact with said temperature sensitive resistor. PG,24 - View Dependent Claims (2, 3, 4, 5)
-
-
6. A thermally compensated silicon pressure sensor comprising:
-
a silicon carbide diaphragm having a top surface and a bottom surface and a thickness permitting flexure when a pressure differential is applied between said top surface and said bottom surface; at least one doped silicon resistor element disposed on said top surface of said diaphragm in a position for exhibiting piezoresistivity when said diaphragm is flexed; a polycrystalline silicon clamp ring disposed on the peripheral portion of the bottom surface of said diaphragm around the entire perimeter of said diaphragm having a thickness providing mechanical support to said diaphragm and permitting virtually no flexure of said clamp ring when a pressure differential is applied between said top surface and said bottom surface of said diaphragm; and a doped silicon temperature sensitive resistor element disposed on the peripheral portion of the top surface of said diaphragm opposite to said clamp ring. - View Dependent Claims (7, 8, 9, 10)
-
Specification