Method of manufacturing a thin piezo resistive pressure sensor
First Claim
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1. A method for forming a sensor comprising the steps of:
- providing a base wafer;
forming a sensor cavity in said base wafer;
after said forming step, coupling a diaphragm wafer to said base wafer, said diaphragm wafer including a diaphragm portion, a sacrificial portion, and an insulating layer disposed between said diaphragm portion and said sacrificial portion, and wherein said diaphragm wafer is coupled to said base wafer such said diaphragm portion generally covers said sensor cavity;
reducing a thickness of said diaphragm wafer by removing at least part of said sacrificial portion while using said insulating layer as an etch stop; and
forming or locating at least one piezo resistive portion on said diaphragm portion.
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Abstract
A method for forming a sensor including the steps of providing a base wafer and forming a sensor cavity in the base wafer. The method further includes the step of coupling a diaphragm wafer to the base wafer, the diaphragm wafer including a diaphragm portion and a sacrificial portion. The diaphragm wafer is coupled to the base wafer such the diaphragm portion generally covers the sensor cavity. The method further includes the steps of reducing the thickness of the diaphragm wafer by removing the sacrificial portion, and forming or locating at least one piezo resistive portion on the diaphragm portion.
85 Citations
32 Claims
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1. A method for forming a sensor comprising the steps of:
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providing a base wafer;
forming a sensor cavity in said base wafer;
after said forming step, coupling a diaphragm wafer to said base wafer, said diaphragm wafer including a diaphragm portion, a sacrificial portion, and an insulating layer disposed between said diaphragm portion and said sacrificial portion, and wherein said diaphragm wafer is coupled to said base wafer such said diaphragm portion generally covers said sensor cavity;
reducing a thickness of said diaphragm wafer by removing at least part of said sacrificial portion while using said insulating layer as an etch stop; and
forming or locating at least one piezo resistive portion on said diaphragm portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for forming a sensor comprising the steps of:
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providing a base wafer;
etching a sensor cavity in said base wafer;
providing a silicon-on-insulator diaphragm wafer including upper and lower silicon layers separated by an insulating layer;
coupling said diaphragm wafer to said base wafer such that a diaphragm portion of said diaphragm wafer is located over said sensor cavity;
etching said base wafer to reduce a thickness of said base wafer;
removing at least said upper silicon layer of said diaphragm wafer to reduce a thickness of said diaphragm portion; and
depositing at least one piezo resistor on said diaphragm portion.
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26. A method for forming a sensor comprising the steps of:
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providing a base wafer;
forming a sensor cavity in said base wafer;
coupling a diaphragm wafer to said base wafer such that a diaphragm portion of said diaphragm wafer is located over said sensor cavity;
reducing a thickness of said base wafer; and
forming or locating at least one piezo resistive portion on said diaphragm portion, wherein said base wafer includes an upper layer, a lower layer, and an insulating layer disposed between said upper layer and said lower layer, and wherein said reducing step includes removing said lower layer of said base wafer while using said insulating layer as an etch stop. - View Dependent Claims (27)
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28. A method for forming a sensor comprising the steps of:
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providing a silicon base wafer;
forming a sensor cavity in said base wafer;
coupling a silicon diaphragm wafer to said base wafer by fusion silicon bonding, said diaphragm wafer including a diaphragm portion, at least one of said base wafer or said diaphragm wafer being a silicon-on-insulator wafer having an upper silicon layer, a lower silicon layer and an insulating layer disposed therebetween, and wherein said diaphragm wafer is coupled to said base wafer such that said diaphragm portion generally covers said sensor cavity; and
forming or locating at least one piezo resistive portion on said diaphragm portion. - View Dependent Claims (29)
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30. A method for forming a sensor comprising the steps of:
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providing a base wafer which is a semiconductor-on-insulator wafer;
forming a sensor cavity in said base wafer;
coupling a diaphragm wafer to said base wafer, said diaphragm wafer being a semiconductor-on-insulator wafer and including a diaphragm semiconductor portion, a sacrificial semiconductor portion, and an insulating layer disposed between said diaphragm portion and said sacrificial portion, and wherein said diaphragm wafer is coupled to said base wafer such said diaphragm portion generally covers said sensor cavity;
reducing a thickness of said diaphragm wafer by removing at least part of said sacrificial portion while using said insulating layer as an etch stop; and
forming or locating at least one piezo resistive portion on said diaphragm portion. - View Dependent Claims (31, 32)
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Specification