Pressure sensor

Details Pressure sensor Pressure sensor

1997-05-22

1999-03-16

Kincaid, Kristine

Electricity: electrical systems and devices

Electrostatic capacitors

Variable

3612834, 73718, 73724, H01G 700

Patent

active

058837795

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a micromechanically producible capacitive pressure sensor.
A closed chamber at a reference pressure is sealed by an elastic diaphragm which is exposed to an external pressure. The electrically conductive diaphragm forms a plate capacitor with the opposite side of this chamber. The diaphragm is deformed because of the pressure difference between the external pressure and the internal reference pressure. The capacitance of this capacitor changes owing to the change in the distance between the diaphragm and the rear side of the chamber, which acts as a counter-electrode. The external pressure can be determined from this change in capacitance.
U.S. Pat. No. 5,095,401 by Paul M. Zavracky et al., describes pressure sensors on an SOI substrate, in which a hollow is produced by removing a region, made from silicon oxide and produced by means of LOCOS, through small openings in a layer applied thereupon. These openings are subsequently sealed by oxidizing the adjoining silicon or by applying a further layer made from silicon nitride, polysilicon or the like. This patent specification also describes the use of the method of production specified there for producing pressure sensors which measure in a capacitive fashion. A constituent of the diaphragm of this pressure sensor is a crystallized silicon layer which is used outside the pressure sensor to integrate electronic components, and is used in the region of the diaphragm to form piezoelectric resistors.


SUMMARY OF THE INVENTION

It is the object of the present invention to specify a micromechanically producible capacitive pressure sensor in which the problem of a nonlinear dependence of the capacitance on the acting pressure is eliminated and to specify an associated production method which can be carried out in a BiCMOS process.
In general terms, the present invention is a pressure sensor as a semiconductor component having a hollow which is bounded on one side by a diaphragm formed essentially by an electrically conductive diaphragm layer. On the side of the hollow averted from the diaphragm there is a region which is doped in an electrically conductive fashion. There is an electrically conductive electrode layer on the side, averted from this hollow, of this diaphragm at a distance from this diaphragm, in which this electrode layer is pierced by holes. These openings are of such a nature, and this diaphragm can e deformed such that in the event that within a prescribed interval there is a change in a pressure prevailing in a medium on the side, averted from this hollow, of this electrode layer, it is possible to measure that change in a voltage, applied via electrical terminals to this diaphragm layer and this electrode layer or this doped region, which is required to counteract a deformation of this diaphragm in an electrostatic fashion. There are contacts for these electrical terminals of this diaphragm layer, of this electrode layer and of the doped region.
Advantageous developments of the present invention are as follows.
There are recesses in the diaphragm layer in the region of this diaphragm which in each case pierce both surfaces of this diaphragm layer. Material of a sealing layer applied to the diaphragm layer is introduced into these recesses. This sealing layer does not cover the side of the diaphragm averted from the hollow.
The diaphragm layer is polysilicon.
The diaphragm layer is metal.
The electrode layer is formed by one or more metal layers.
The present invention is also a method for producing a pressure sensor that has the following steps: region and the diaphragm layer is applied thereto; diaphragm to e produced, recesses of a size dimensioned for the following steps c) and d); recesses; are sealed without the hollow being filled up; the electrode layer is etched away in the region of the diaphragm to be produced, and the means required to apply a voltage to the diaphragm layer and the electrode layer are produced.
In a development of the present invention, a diaphragm layer is

REFERENCES:
patent: 4332000 (1982-05-01), Petersen
patent: 4665610 (1987-05-01), Barth
patent: 4831492 (1989-05-01), Kuisma
patent: 5095401 (1992-03-01), Zavracky et al.
Industriellen-Messtechnik, IBM Composer pp. 11-12 Dec. 1983--Professor Dr. P. Profos.
Application of Electrostatic Feedback To Critical Damping of an Integrated Silicon Capacitive Accelerometer--Sensors and Actuators A, 43 (1994) 100-106--R.P. van Kampen et al.

Affiliated with

Also associated with

Rating

Pressure sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Pressure sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pressure sensor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-822700