Measuring and testing – Speed – velocity – or acceleration – Acceleration determination utilizing inertial element
Patent
1988-02-09
1989-10-17
Chapman, John
Measuring and testing
Speed, velocity, or acceleration
Acceleration determination utilizing inertial element
7386168, G01P 1508, G01P 15125
Patent
active
048738689
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a mechanical magnitude sensor integrated on silicon, comprising a monocrystaline silicon substrate having a first type of doping (A), a variable capacitor comprising a moving first plate constituted by the free end of a conducting blade which is deformable in bending and which is mounted so as to have a cantilevered portion, and a fixed second plate constituted by a conducting zone made on the fixed free surface of the sensor facing said first plate and separated therefrom by an empty space which is a few microns across, and means for detecting a meaningful electrical signal representative of variations in the position of said flexible blade.
PRIOR ART
It is already known to provide integrated force measurement sensors of this type for measuring forces, accelerations, or pressures, and comprising a small cantilevered beam formed in a silicon chip in order to constitute, within an integrated circuit, an element which is sensitive to accelerations perpendicular to the surface of the silicon chip in order to give rise to variations in the capacitance of a variable capacitor, and thereby make it possible to deliver an electrical signal representative of the measured magnitude by detecting variations in the capacitance.
The provision of a sensor which is integrated on silicon makes it possible to increase cmopatibility with the digital processing electronic circuits that are associated with the sensors. However, prior art capacitive effect integrated force measurement sensors suffer from drawbacks insofar as the means for detecting the variations in the capacitance of the variable capacitor having one of its plates constituted by a flexible blade make use of MOS (metal-oxide-semiconductor) type structures which do not make it possible to obtain measurements of sufficient reliability or accuracy because of stray capacitance, drift over time, a relatively high degree of noise, and because of the impossibility of imposing a low cutoff frequency.
Also, it is difficult to manufacture sensors which incorporate a cantilevered blade situated at a very small distance from the substrate, e.g. a few microns, and it is often difficult to prevent the blade sticking on the substrate (or to unstick it therefrom) due to the attraction between two zones of different doping when the distance between said two zones is very small.
SUMMARY OF THE INVENTION
The present invention seeks to remedy the above-mentioned drawbacks and to make it possible to provide a force measurement sensor integrated on silicon, with the fabrication and the size of the sensor being compatible with electronic integrated circuit technology, which sensor can be fabricated accurately and safely, and whose sensitivity and reliability are improved so as to enable accurate measurements to be performed even under difficult environmental conditions.
These aims are achieved by means of a sensor of the type defined at the beginning of the description and characterized in that the substrate is covered on at least a portion of its surface in a doped layer having a second type of doping (B), in that said deformable conductive blade has a conducting anchor portion applied to a localized zone of said doped layer, in that the sensor includes, in said doped layer, a first doped zone which is doped with a high concentration of impurities of the first type (A.sup.+) situated in said localized zone for anchoring the flexible blade in order to constitute the gate G of a junction field effect transistor (JFET), second and third doped zones which are doped with a high concentration of impurities of the second type (B.sup.+) situated on either side of said first doped zone to constitute the drain D and source S zones of the JFET, the doped layer defining a zone having a low concentration of impurities of said second type (B) situated beneath said first doped zone between said second and third doped zones in order to constitute the channel of said JFET whose gate G is directly connected via the flexible blade to the moving p
REFERENCES:
patent: 4342227 (1982-08-01), Peterson et al.
patent: 4483194 (1984-11-01), Rudolf
patent: 4507705 (1985-03-01), Hoshino
patent: 4571661 (1986-02-01), Hoshino
patent: 4670092 (1987-06-01), Montamedi
patent: 4672849 (1987-06-01), Hoshino
Gray, Paul R., Meyer, Robert G., Analysis and Design of Analog Integrated Circuits, Second edition, 1984, pp. 46-67, 124-133.
Batllteu Francois
Brosselard Jean-Pierre
Permuy Alfred
Pierre Andre
Pirot Francois-Xavier
Bell Robert P.
Chapman John
Metravib R.D.S.
LandOfFree
Force measurement sensor integrated on silicon, and a method of does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Force measurement sensor integrated on silicon, and a method of , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Force measurement sensor integrated on silicon, and a method of will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1737700