Batch-process silicon capacitive pressure sensor
First Claim
1. A method for making a capacitive pressure sensor comprising the steps of:
- (1) providing first and second wafers of conductively-doped semiconductor material;
(2) oxidizing a major surface of each of said wafers to form a layer of oxidized material thereon;
(3) removing a predefined area of said oxidized layer from said first wafer, leaving an uncovered surface of unoxidized semiconductor material in said predefined area;
(4) superimposing said second wafer onto said first wafer so that the oxidized layer of said second wafer is in contact with the oxidized layer of said first wafer around said predefined area;
(5) applying sufficient heat and pressure to said first and second wafers to fuse together the contacting oxidized layers;
(6) metallizing preselected areas of the outer surfaces of the fused-together first and second wafers to form a metallized layer on each of said outer surfaces; and
(7) cutting the fused-together wafers to form at least one capacitive pressure sensor having first and second conductive semiconductor plates separated by a gap formed between said uncovered surface in said predefined area of said first wafer and the opposed oxidized layer of said second wafer, each of said plates including a portion of one of said metallized layers on its outer surface.
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Abstract
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.
97 Citations
28 Claims
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1. A method for making a capacitive pressure sensor comprising the steps of:
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(1) providing first and second wafers of conductively-doped semiconductor material; (2) oxidizing a major surface of each of said wafers to form a layer of oxidized material thereon; (3) removing a predefined area of said oxidized layer from said first wafer, leaving an uncovered surface of unoxidized semiconductor material in said predefined area; (4) superimposing said second wafer onto said first wafer so that the oxidized layer of said second wafer is in contact with the oxidized layer of said first wafer around said predefined area; (5) applying sufficient heat and pressure to said first and second wafers to fuse together the contacting oxidized layers; (6) metallizing preselected areas of the outer surfaces of the fused-together first and second wafers to form a metallized layer on each of said outer surfaces; and (7) cutting the fused-together wafers to form at least one capacitive pressure sensor having first and second conductive semiconductor plates separated by a gap formed between said uncovered surface in said predefined area of said first wafer and the opposed oxidized layer of said second wafer, each of said plates including a portion of one of said metallized layers on its outer surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for making a capacitive pressure sensor comprising the steps of:
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(1) providing first and second wafers of conductively-doped silicon; (2) oxidizing a major surface of each of said wafers to form a layer of silicon dioxide therein; (3) removing silicon dioxide from a matrix of plural separate predefined areas on the oxidized major surface of said first wafer, leaving an uncovered surface of silicon in each of said predefined areas; (4) superimposing said second wafer onto said first wafer so that the silicon dioxide layer of said second wafer is in contact with the silicon dioxide layer of said first wafer around and between said predefined areas; (5) fusing together the contacting silicon dioxide layers by the application of heat and pressure to said first and second wafers; (6) metallizing pre-selected areas of the outer surface of the fused-together first and second wafers to form a metallized layer on each of said outer surfaces; and (7) cutting the fused-together wafers to form a plurality of capacitive pressure sensors each having first and second conductive silicon plates separated by a gap formed between the uncovered silicon surface in one of said plural predefined areas and the opposed silicon dioxide layer of said second wafer, each of said plates including a portion of one of said metallized layers on its outer surface. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A silicon capacitive pressure sensor manufactured by a method comprising the steps of:
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(1) providing first and second wafers of conductively-doped silicon; (2) forming a first layer of silicon dioxide on a major surface of said first wafer and a second layer of silicon dioxide on a major surface of said second wafer; (3) forming a matrix of plural, separate uncovered silicon areas on said first wafer by removing a matrix of predefined areas of said first silicon dioxide layer; (4) bringing said first and second silicon dioxide layers into mutual contact under sufficient heat and pressure to effect a fusing together of said first and second wafers at the contacting portions of said first and second silicon dioxide layers; (5) forming a metallized layer on an outer surface of each of the fused-together wafers; and (6) cutting the fused-together wafers into a plurality of capacitive pressure sensors each having first and second conductive silicon plates separated by a gap formed between the uncovered silicon in one of said plural predefined areas in said first wafer and the opposed silicon dioxide layer on said second wafer, each of said plates including a portion of one of said metallized layers on its outer surface. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A silicon capacitive pressure sensor, comprising:
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first and second plates of conductively-doped silicon separated by a dielectric gap and joined to each other around said gap by fused-together layers of silicon dioxide; and a metallized electrical contact on an outer surface of each of said plates; whereby at least one of said plates is deflectable into said gap by the application of pressure to an outer surface thereof. - View Dependent Claims (25, 26, 27, 28)
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Specification