Silicon pressure sensor chip with a shear element on a sculptured diaphragm
First Claim
Patent Images
1. A pressure sensor having only one point-like sensing element and comprising:
- a single monocrystalline silicon diaphragm capable of flexing in response to pressure changes and having a first portion having a predetermined thickness, and a second portion having a predetermined thickness less than that of the first portion; and
said one point-like sensing element formed entirely in said first portion of said diaphragm, wherein an electrical resistance of said sensing element varies with the pressure changes on said second portion of said diaphragm.
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Abstract
A silicon pressure sensor chip has a shear element on a sculptured diaphragm. The shear element is a piezo-resistive four-terminal resistor which is oriented so as to respond to the in-plane shear stress component in the diaphragm. The shear element is located on a thick shelf which is a portion of the sculptured diaphragm, which also has a thinner portion. This diaphragm configuration increases the bending moment at the location of the sensing element through the load of the thin portion of the diaphragm, which is suspended along the periphery of the thick shelf.
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Citations
13 Claims
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1. A pressure sensor having only one point-like sensing element and comprising:
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a single monocrystalline silicon diaphragm capable of flexing in response to pressure changes and having a first portion having a predetermined thickness, and a second portion having a predetermined thickness less than that of the first portion; and said one point-like sensing element formed entirely in said first portion of said diaphragm, wherein an electrical resistance of said sensing element varies with the pressure changes on said second portion of said diaphragm. - View Dependent Claims (2, 3, 4, 5, 8)
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6. A pressure sensor chip comprising:
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a monocrystalline silicon diaphragm capable of flexing in response to pressure changes and having a first portion havign a predetermined thickness, and a second portion having a predetermined thickness less than that of the first portion; and a piezo-resistive sensing element formed in said first portion of said diaphragm, whereby an electrical resistance of said sensing element varies with the pressure changes on said diaphragm; wherein said first portion of said diaphragm is triangular in shape in a plane of said diaphragm, a corner of said first portion being located about at a center of said diaphragm, and wherein said sensing element is located at one side of said first portion, and adjacent to an edge of said diaphragm. - View Dependent Claims (7)
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9. A pressure sensor chip comprising:
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a silicon body of a first conductivity type capable of flexing in response to pressure changes and having a principal surface and an opposing back surface; a first semiconductor region of a second conductivity type formed in said body and extending from said principal surface to a first depth into said body; a second semiconductor region of the second conductivity type formed in said body adjacent to said first semiconductor region and extending from said principal surface to a second depth less that said first depth into said body; a single recess defined by said body and extending from said back surface to said first and second semiconductor regions; and a piezo-resistive sensing element formed entirely in said first semiconductor region, whereby an electrical resistance of said sensing element varies with the pressure changes on said body.
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10. A method for making a sensor chip comprising the steps of:
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providing a silicon substrate having a principal surface; forming a first recess in a surface of said substrate opposite to said principal surface so as to define a diaphragm; forming a second recess in said principal surface so as to define a single first portion of said diaphragm which is thinner than a second portion of said diaphragm; and forming a piezo-resistive sensing element entirely in said second portion of said diaphragm.
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11. A method for making a sensor chip comprising the steps of:
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providing a substrate of a first conductivity type and having a principal surface; forming a first region in said principal surface having a second conductivity type opposite to said first conductivity type and having a predetermined depth; forming a second region in said principal surface having said second conductivity type and a depth greater than that of said first region; etching a single recess in a surface of said substrate opposite to said principal surface, said recess being defined by the depths of said first and second region; and forming a piezo-resistive sensing element entirely in said second region.
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12. A pressure sensor chip comprising:
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a monocrystalline silicon diaphragm capable of flexing in response to pressure changes and having a first portion having a predetermined thickness, and a second portion having a predetermined thickness less than that of the first portion; and a piezo-resistive sensing element formed in said first portion of said diaphragm, whereby an electrical resistance of said sensing element varies with the pressure changes on said diaphragm; wherein said first portion of said diaphragm is triangular in shape in a plane of said diaphragm, a corner of said first portion being located about a center of said diaphragm and wherein said sensing element is located at one said of said first portion, and adjacent to an edge of said diaphragm. - View Dependent Claims (13)
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Specification