Bourns Instruments, Inc.

Arthur J Peters

Eugene A Marks

A diaphragm-type pressure sensor employs a monocrystalline wafer as a pressure-responsive diaphragm. The wafer has a central active area surrounded by a first bonding area on one side and a second bonding area on the other side. The first bonding area is attached by a first layer of bonding material to a base, and the second bonding area is attached by a second layer of bonding material to a cap. The inside diameter of the first bonding layer is greater than the inside diameter of the second bonding layer by an amount of at least approximately six times the thickness of the diaphragm. This disparity between the respective inside diameters of the two bonding layers results in the relief of radially-directed tensile loading on the first bonding layer when a pressure to be measured is applied to the first side of the diaphragm. Consequently, the probability of a fracture occurring in this bonding layer is minimized.

Diaphragm pressure sensor with improved tensile loading characteristics

Silicon capacitive pressure sensors are produced by a batch-process method, comprising the steps of: (1) providing first and second wafers of conductive silicon; (2) oxidizing a surface of each wafer with a layer of silicon dioxide; (3) removing a predefined area of the silicon dioxide layer from a first one of the wafers, leaving an exposed surface of unoxidized silicon in the predefined area; (4) superimposing the second wafer onto the first wafer so that the silicon dioxide layer of the second wafer is in contact with the silicon dioxide layer of the first wafer; (5) fusing the two wafers together at their contacting silicon dioxide layers; (6) metallizing selected areas of the outer surfaces of the two wafers to form electrical contacts; and (7) cutting the wafers into individual pressure sensors. Each of the individual sensors so formed has a pair of opposed conductive silicon plates separated by a dielectric gap formed between the predefined unoxidized area of the first wafer and the opposed silicon dioxide layer of the second wafer. At least one of the plates is formed to be deflectable into the gap in response to the application of pressure to its outer surface.

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Norco, CA, United States of America

Arthur J Peters