Method of making an ultraminiature pressure sensor
First Claim
1. A method of making a pressure sensor having a diaphragm and rim structure including bulk silicon, comprising the steps of:
- (a) providing a silicon wafer;
(b) forming at least one mesa upon the silicon wafer to be used as part of the rim structure of the pressure sensor;
(c) impregnating a selected portion of the silicon wafer which includes the mesa with at least a first material which alters an etching characteristic of the first selected portion;
(d) impregnating a second selected portion of the silicon wafer which will become the diaphragm of the sensor with a second material which alters an etching characteristic of the second selected portion; and
(e) removing by etching at least a selected third portion of the silicon wafer adjacent to the first and second portions as part of forming the diaphragm and rim structure.
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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 tranducer 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.
107 Citations
23 Claims
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1. A method of making a pressure sensor having a diaphragm and rim structure including bulk silicon, comprising the steps of:
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(a) providing a silicon wafer; (b) forming at least one mesa upon the silicon wafer to be used as part of the rim structure of the pressure sensor; (c) impregnating a selected portion of the silicon wafer which includes the mesa with at least a first material which alters an etching characteristic of the first selected portion; (d) impregnating a second selected portion of the silicon wafer which will become the diaphragm of the sensor with a second material which alters an etching characteristic of the second selected portion; and (e) removing by etching at least a selected third portion of the silicon wafer adjacent to the first and second portions as part of forming the diaphragm and rim structure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of making a miniature force-sensing device having at least one movable member and support structure therefor, made from bulk silicon, comprising the steps of:
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(a) providing a single-crystal silicon wafer; (b) forming at least one mesa upon the silicon wafer to be used as at least part of the support structure for the movable member; (c) impregnating a first selected portion of the silicon wafer which includes the mesa with at least a first material which alters an etching characteristic of the first selected portion; (d) impregnating a second selected portion of the silicon wafer which will become at least part of the movable member of the force-sensing device with a second material which alters an etching characteristic of the second selected portion; and (e) removing by etching at least a selected third portion of the silicon wafer adjacent to the first and second portions as part of forming the movable member and support structure therefor. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of forming a transducer having first and second electrically conductive parallel plates which form a capacitor whose capacitance is adjustable by a change in force upon at least one of the plates, the method comprising the steps of:
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a. providing an insulating support substrate; b. forming an electrically conductive plate on a first side thereof, which plate constitutes the first parallel plate; c. forming from a wafer of single-crystal semiconductor material by using at least one deep diffusion step and at least one shallow diffusion step, a monolithic structure including a movable member of single-crystal material and a ridid base for supporting the movable member, with the movable member constituting the second parallel plate; and d. bonding the rigid structure to the first side of the support substrate adjacent to the first parallel plate. - View Dependent Claims (21, 22, 23)
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Specification