Ultraminiature pressure sensor and method of making same
First Claim
1. An ultraminiature solid-state capacitive pressure transducer which includes a parallel plate capacitor, comprising:
- an integrally formed structure made from single-crystal material and having a diaphragm and a rim extending about a substantial portion of the periphery of the diaphragm, the structure having at least two dimensions orthogonal to one another of less than one millimeter, and the diaphragm constituting a plane supporting one plate of the parallel plate capacitor.
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Accused Products
Abstract
A capacitive pressure sensor suitable for making highly sensitive, low pressure measurements is disclosed. The sensor may be mounted into a 0.5 mm OD catheter suitable for multipoint pressure measurements from within the coronary artery of the heart. The sensor employs a transducer which consists of a rectangular bulk silicon micro-diaphragm several hundred microns on a side by two microns thick, surrounded by a supporting bulk silicon rim about 12 microns thick. Both the diaphragm and the rim are defined by a double diffusion etch-stop technique. The transducer fabrication process features a batch wafer-to-glass electrostatic seal followed by a silicon etch, which eliminates handling of individual small diaphragm structures until die separation and final packaging. An addressable read-out interface circuit may be used with the sensor to provide a high-level output signal, and allows the sensor to be compatible for use on a multisite catheter having only two electrical leads.
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Citations
24 Claims
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1. An ultraminiature solid-state capacitive pressure transducer which includes a parallel plate capacitor, comprising:
an integrally formed structure made from single-crystal material and having a diaphragm and a rim extending about a substantial portion of the periphery of the diaphragm, the structure having at least two dimensions orthogonal to one another of less than one millimeter, and the diaphragm constituting a plane supporting one plate of the parallel plate capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A solid-state capacitive pressure transducer including a parallel plate capacitor therein, comprising:
an integrally formed structure made from single-crystal silicon semiconductor material and having a diaphragm and a rim that extends at least around a substantial portion of the periphery of the diaphragm, the diaphragm and rim being heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the diaphragm and rim except for containing substantially less of such first material, and wherein the diaphragm constitutes a supporting plane of one plate of the parallel plate capacitor. - View Dependent Claims (14, 15, 16)
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17. A transducer including a pressure-adjustable parallel plate capacitor, comprising:
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a first electrically conductive plate; and an integrally formed structure made from single-crystal silicon semiconductor material and having a diaphragm and a rim that extend entirely around the periphery of the diaphragm and mechanically supports the diaphragm in a nominal position parallel to and at a predetermined nominal distance from the first plate, the diaphragm and rim being electrically conductive and heavily impregnated with at least a first material which alters an etching characteristic thereof in comparison to single-crystal material which is identical to the heavily impregnated material of the diaphragm and rim except for containing substantially less of such first material, the diaphragm constituting a second electrically conductive plate, and being sufficiently thin relative to its overall size to allow it to respond to a mechanical force applied which is thereto in the form of changing pressure in a range designed to be measured by said transducer, thereby changing the capacitance of the parallel place capacitor. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification