Episeal pressure sensor and method for making an episeal pressure sensor
First Claim
1. A method for making a pressure sensor, comprising:
- providing a wafer including at least a base silicon layer, a buried sacrificial layer, and a top silicon layer, the top silicon layer arranged over the buried sacrificial layer, the buried sacrificial layer arranged over the base silicon layer;
etching at least one vent through the top silicon layer to the buried sacrificial layer;
removing at least a portion of the buried sacrificial layer to form a cavity;
depositing a sealing silicon bearing compound to seal the at least one vent; and
arranging a sensing element on the wafer;
wherein the etching of the at least one vent includes etching at least one tapered vent, the at least one tapered vent having a first cross section towards a top of the top silicon layer and a second cross section towards the buried sacrificial layer, a first width of the first cross section being greater than a second width of the second cross section, the first width being parallel to the second width.
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Accused Products
Abstract
A method for making a pressure sensor by providing a wafer including a base silicon layer, a buried sacrificial layer, and a top silicon layer. The top silicon layer is arranged over the buried sacrificial layer and the buried sacrificial layer is arranged over the base silicon layer. Etching vents through the top silicon layer to the buried sacrificial layer and removing a portion of the buried sacrificial layer. Depositing silicon to seal the vents and arranging a strain gauge or a capacitance contact on the wafer. A method for making a pressure sensor including providing a bulk wafer and depositing a sacrificial layer on the bulk wafer. Depositing silicon on the sacrificial layer and the bulk wafer to form an encapsulation layer. Etching vents through the encapsulation layer to the sacrificial layer and removing the sacrificial layer. Closing the vents with a silicon deposition and arranging a strain gauge or a capacitance contact on the encapsulation layer. A pressure sensing device including a substrate, an encapsulation layer with vents, and voids between the substrate and the encapsulation layer. A portion of the encapsulation layer above the voids forms a membrane and deposited silicon plugs fill the vents. A strain gauge or a top capacitive contact arranged on the membrane.
87 Citations
68 Claims
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1. A method for making a pressure sensor, comprising:
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providing a wafer including at least a base silicon layer, a buried sacrificial layer, and a top silicon layer, the top silicon layer arranged over the buried sacrificial layer, the buried sacrificial layer arranged over the base silicon layer;
etching at least one vent through the top silicon layer to the buried sacrificial layer;
removing at least a portion of the buried sacrificial layer to form a cavity;
depositing a sealing silicon bearing compound to seal the at least one vent; and
arranging a sensing element on the wafer;
wherein the etching of the at least one vent includes etching at least one tapered vent, the at least one tapered vent having a first cross section towards a top of the top silicon layer and a second cross section towards the buried sacrificial layer, a first width of the first cross section being greater than a second width of the second cross section, the first width being parallel to the second width. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for making a pressure sensor, comprising:
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providing a wafer including at least a base silicon layer, a buried sacrificial layer, and a top silicon layer, the top silicon layer arranged over the buried sacrificial layer, the buried sacrificial layer arranged over the base silicon layer;
etching at least one vent through the top silicon layer to the buried sacrificial layer;
removing at least a portion of the buried sacrificial layer to form a cavity;
depositing a sealing silicon bearing compound to seal the at least one vent; and
arranging a sensing element on the wafer;
wherein the depositing of the sealing silicon bearing compound to seal the at least one vent further includes establishing an epitaxy reactor atmosphere containing gaseous hydrogen with an entrained compound containing silicon. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method for making a pressure sensor, comprising:
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providing a wafer including at least a base silicon layer, a buried sacrificial layer, and a top silicon layer, the top silicon layer arranged over the buried sacrificial layer the buried sacrificial layer arranged over the base silicon layer;
etching at least one vent through the top silicon layer to the buried sacrificial layer;
removing at least a portion of the buried sacrificial layer to form a cavity;
depositing a sealing silicon bearing compound to seal the at least one vent; and
arranging a sensing element on the wafer;
wherein; the wafer includes a passage communicating gases from a backside of the base silicon layer to the cavity, the passage equalizing a backside pressure and a cavity pressure; and
the sensing element measures a pressure differential between a frontside pressure on the frontside of the wafer and the backside pressure on the backside of the wafer. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49)
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50. A method for making a pressure sensor, comprising:
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providing a bulk wafer;
providing a sacrificial layer on at least part of the bulk wafer;
depositing silicon on at least one of a first portion of the sacrificial layer and a second portion of the bulk wafer to form an encapsulation layer;
etching at least one vent through the encapsulation layer to a third portion of the sacrificial layer;
removing the third portion of the sacrificial layer;
closing the at least one vent by depositing a silicon bearing compound; and
arranging a sensing element on the encapsulation layer. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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Specification