Laminated semiconductor sensor with overpressure protection

Claim 2

An electromechanical sensor comprising: a first semiconductor wafer including a first stop surface residing in a first shallow recessed region of said first wafer; a second semiconductor wafer; wherein said first and second semiconductor wafers are laminated together such that said first recessed region of said first wafer and said second wafer define a first chamber in which said first stop surface and said second wafer are disposed close enough together such that said first stop surface restrains said second wafer from deflecting beyond said first stop surface; and means for measuring deflection of said second wafer.

Claim 3

The sensor of Claim 1 wherein: said second wafer includes a first contact surface residing in a second shallow recessed region of said second wafer; and said first stop surface and said first contact surface are disposed substantially opposite each other in said first chamber.

Claim 4

The sensor of Claim 2 wherein said first and second chambers are substantially contiguous.

Claim 5

The sensor of Claim 2 wherein said second shallow recessed region includes a center section and a thinner perimeter section which substantially surrounds said center section.

Claim 6

The sensor of Claim 1 and further comprising a first fluid feedthrough port formed in said first wafer to provide fluid communication with said first chamber.

Claim 7

The sensor of Claim 5 and further comprising: means for filtering fluid provided to said first fluid feedthrough port.

Claim 8

The sensor of Claim 6 wherein said means for filtering includes a plurality of channels each having narrower lateral dimensions than said first fluid feedthrough port.

Claim 9

The sensor of Claim 5 wherein: said first fluid feedthrough port is disposed in said first wafer in laterally spaced relation to said first chamber; and said first and second wafers together define at least one tubular conduit for providing fluid coupling between said first fluid feedthrough port and said first chamber.

Claim 10

The sensor of Claim 8 and further comprising: means for filtering fluid provided to said at least one tubular conduit.

Claim 11

The sensor of Claim 5 and further comprising: means for preventing said first wafer from adhering to said first stop surface.

Claim 12

The sensor of Claim 10 wherein said means for preventing includes a plurality of relatively short upstanding members formed in said first stop surface such that said plurality of upstanding members abut against said first wafer when said first stop surface restrains said first wafer.

Claim 13

The sensor of Claim 10 wherein said means for preventing includes a plurality of relatively short upstanding members formed in said first wafer such that said plurality of upstanding members abut against said first stop surface when said first stop surface restrains said first wafer.

Claim 14

The sensor of Claim 11 wherein said upstanding members are spaced apart such that fluid provided to said first port can flow within spaces between said upstanding members when said plurality of upstanding members abut against said first wafer.

Claim 15

The sensor of Claim 8 wherein said upstanding members are spaced apart such that fluid provided to said first port can flow within spaces between said upstanding members when said plurality of upstanding members abut against said first stop surface.

Claim 16

The sensor of Claim 1 wherein: said first and second semiconductor wafers are formed from silicon.

Claim 17

The sensor of Claim 15 wherein said first wafer has an oxide layer formed thereon.

Claim 18

The sensor of Claim 16 wherein said second wafer has an oxide layer formed thereon.

Claim 19

The sensor of Claim 15 wherein said second wafer is formed from n-type silicon.

Claim 20

The sensor of Claim 1 wherein said means for measuring comprises at least one piezoresistive element formed in said second wafer.

Claim 21

The sensor of Claim 19 wherein: said means for measuring comprises a plurality of piezoresistive elements formed in said second wafer.

Claim 22

The sensor of Claim 20 and further comprising: at least one electrical feedthrough formed in said first wafer to provide electrical communication between a laminated surface of said first wafer and an unlaminated surface of said first wafer; and means for coupling electrical signals between said at least one electrical feedthrough and said means for measuring.

Claim 23

The sensor of Claim 20 wherein: said first and second wafers are formed from silicon; said second wafer is formed from n-type silicon; and said means for coupling includes a plurality of P-type regions formed in said second wafer so as to couple said plurality of piezoresistive elements in the form of a Wheatstone Bridge.

Claim 24

The sensor of Claim 21 comprising: a plurality of respective conductive regions diffused in a bonded surface of said semiconductor member; a plurality of respective electrical feedthroughs formed in said first wafer to provide electrical communication between a laminated surface of said first wafer and an unlaminated surface of said first wafer; a plurality of respective metallized regions, each formed in a different respective electrical feedthrough port such that each respective metallized region is electrically coupled to said means for coupling.

Claim 25

The sensor of Claim 1 wherein said means for measuring comprises at least one capacitive element including at least one first electrode formed in said first stop surface and at least one second electrode formed in said second wafer.

Claim 26

The sensor of Claim 1 and further comprising: a third semiconductor wafer including a second stop surface residing in a third shallow recessed region of said third wafer; wherein said second and third semiconductor wafers are laminated together such that said third recessed region of said third layer and said second wafer define a second chamber in which said second stop surface and said second wafer are disposed close enough together such that said second stop surface restrains said second wafer from deflecting beyond said second stop surface.

Claim 27

The sensor of Claim 1 wherein: said second wafer includes a diaphragm region including a first contact surface, said diaphragm being suitable to withstand at least a prescribed amount of deflection without sustaining damage; and said first contact surface of said diaphragm is disposed substantially opposite said first stop surface within said first chamber; and said first contact surface and said first stop surface are separated by a predetermined distance selected such that said first contact surface abuts against said first stop surface before said diaphragm reaches said prescribed amount of deflection.

Claim 28

An electromechanical sensor comprising: a first silicon wafer including a first stop surface residing in a first shallow recessed region of said first wafer; a second silicon wafer including a diaphragm including first and second contact surfaces, said diaphragm being suitable to withstand at least a prescribed amount of deflection without sustaining change; a third silicon wafer including a second stop surface residing in a second shallow recessed region of said third wafer; wherein said first, second and third wafers are laminated together with said second wafer sandwiched between said first and third wafers such that said first recessed region and said first contact surface define a first chamber and said second recessed region and said second contact surface define a second chamber; wherein said first contact surface and said first stop surface are disposed opposite each other in said first chamber and are separated by a predetermined distance selected such that said first contact surface abuts against said first stop surface before said diaphragm reaches said prescribed amount of deflection; wherein said second contact surface and said second stop surface are disposed opposite each other in said second chamber and are separated by a prescribed distance selected such that said second contact surface abuts against said second stop surface before said diaphragm reaches said prescribed amount of deflection; means for measuring deflection of said diaphragm; a first fluid feedthrough port formed in said first wafer to provide fluid communication with said first chamber; a second fluid feedthrough port formed in said third wafer to provide fluid communication with said second chamber; first means for preventing said first stop surface and said first contact surface from adhering together; and second means for preventing said second stop surface and said second contact surface from adhering together.

Claim 29

An electromechanical sensor comprising: a first silicon wafer including a first stop surface residing in a first shallow recessed region of said first wafer; a second silicon wafer including a diaphragm including first and second contact surfaces, said diaphragm being suitable to withstand at least a prescribed amount of deflection without sustaining change; a third silicon wafer including a second stop surface residing in a second shallow recessed region of said third wafer; wherein said first, second and third wafers are laminated together with said second wafer sandwiched between said first and third wafers such that said first recessed region and said first contact surface define a first chamber and said second recessed region and said second contact surface define a second chamber; wherein said first contact surface and said first stop surface are disposed opposite each other in said first chamber and are separated by a predetermined distance selected such that said first contact surface abuts against said first stop surface before said diaphragm reaches said prescribed amount of deflection; wherein said second contact surface and said second stop surface are disposed opposite each other in said second chamber and are separated by a prescribed distance selected such that said second contact surface abuts against said second stop surface before said diaphragm reaches said prescribed amount of deflection; means for measuring deflection of said diaphragm; a first fluid feedthrough port formed in said first wafer to provide fluid communication with said first chamber; a second fluid feedthrough port formed in said third wafer to provide fluid communication with said second chamber; first means for preventing said first stop surface and said first contact surface from adhering together; and second means for preventing said second stop surface and said second contact surface from adhering together.

Claim 30

The sensor of Claim 27 wherein said first and second contact surfaces reside in respective recessed regions on opposite sides of said diaphragm.

Claim 31

The sensor of Claim 27 wherein: said first and second fluid feedthrough ports are respectively disposed in laterally spaced relation to said respective first and second chambers; said first and second wafers together define at least one first tubular conduit for providing fluid coupling between said first fluid feedthrough port and said first chamber; and said second and third wafers together define at least one second tubular conduit for providing fluid coupling between said second fluid feedthrough port and said second chamber.

Claim 32

The sensor of Claim 29 and further comprising: first means for filtering fluid provided to said at least one first tubular conduit by said first fluid feedthrough port; and second means for filtering fluid provided to said at least one second tubular conduit by said second fluid feedthrough port.

Claim 33

The sensor of Claim 30 wherein said diaphragm comprises a center section and thinner, perimeter section which substantially surrounds said center section.

Claim 42

The method of Claim 34 and further comprising the step of forming a plurality of upstanding members in said second contact surface.

Claim 43

The method of Claim 34 and further comprising the step of forming a plurality of upstanding members in said second stop surface.

Claim 44

An electromechanical sensor produced according to a process comprising the steps of: forming a first shallow recessed region in a first surface of a semiconductor wafer, said first recessed region including a first stop surface; forming a second shallow recessed region in a first surface of a second semiconductor wafer, said second recessed region including a first contact surface; forming at least one piezoresistor in said second shallow recessed region; treating said first and second wafers to make them hydrophylic; bringing said respective first surfaces of said first and second wafers into contact with each other and aligning said first and second wafers such that said first stop surface and said first contact surface are disposed substantially opposite each other within a first chamber defined by said first and second recessed regions; and exposing said contacting and aligned first and second wafers to an oxidizing environment at a temperature of 400°C - 1200°C

Claim 45

An electromechanical sensor produced according to a process comprising the steps of: forming a first shallow recessed region in a first surface of a semiconductor wafer, said first recessed region including a first stop surface; forming a second shallow recessed region in a first surface of a second semiconductor wafer, said second recessed region including a first contact surface; forming at least one piezoresistor in said second shallow recessed region; treating said first and second wafers to make them hydrophylic; bringing said respective first surfaces of said first and second wafers into contact with each other and aligning said first and second wafers such that said first stop surface and said first contact surface are disposed substantially opposite each other within a first chamber defined by said first and second recessed regions; and exposing said contacting and aligned first and second wafers to an oxidizing environment at a temperature of 400°C - 1200°C

Claim 46

An electromechanical sensor produced according to a process comprising the steps of: forming a first shallow recessed region in a first surface of a first semiconductor wafer such that said recessed region has a prescribed depth and includes a first stop surface; forming a thinned region in a second semiconductor wafer such that said thinned region can withstand at least a prescribed amount of deflection without sustaining damage, said thinned region including a first contact surface on a first surface of said second wafer; forming at least one piezoresistor in said thinned region; treating said first and second wafers to make them hydrophylic; bringing said respective first surfaces of said first and second wafers into contact with each other and aligning said first and second wafers such that said first stop surface and said first contact surface are disposed substantially opposite each other within a first chamber defined by said first recessed region and said thinned region; and exposing said contacting and aligned first and second wafers to an oxidizing environment at a temperature of 400°C - 1200°C; wherein said prescribed depth is selected such that said first contact surface and said first stop surface are disposed close enough together within said first chamber such that said first contact surface abuts against said first stop surface before said thinned region reaches said prescribed amount of deflection.

Claim 47

An electromechanical sensor produced according to a process comprising the steps of: forming a first shallow recessed region in a first surface of a first semiconductor wafer such that said recessed region has a prescribed depth and includes a first stop surface; forming a thinned region in a second semiconductor wafer such that said thinned region can withstand at least a prescribed amount of deflection without sustaining damage, said thinned region including a first contact surface on a first surface of said second wafer; forming at least one piezoresistor in said thinned region; treating said first and second wafers to make them hydrophylic; bringing said respective first surfaces of said first and second wafers into contact with each other and aligning said first and second wafers such that said first stop surface and said first contact surface are disposed substantially opposite each other within a first chamber defined by said first recessed region and said thinned region; and exposing said contacting and aligned first and second wafers to an oxidizing environment at a temperature of 400°C - 1200°C; wherein said prescribed depth is selected such that said first contact surface and said first stop surface are disposed close enough together within said first chamber such that said first contact surface abuts against said first stop surface before said thinned region reaches said prescribed amount of deflection.

Claim 48

An electromechanical sensor produced according to a process comprising the steps of: forming a first shallow first recessed region in a first surface of a first semiconductor wafer such that said first recessed region has a prescribed depth and includes a first stop surface; forming a thinned region in a second semiconductor wafer such that said thinned region can withstand at least a prescribed amount of deflection without sustaining damage, said thinned region including a first contact surface on a first surface of said second semiconductor wafer and including a second contact surface on a second surface of said second semiconductor wafer; forming a shallow second recessed region in a first surface of a third semiconductor wafer such that said second recessed region has a prescribed depth and includes a second stop surface; forming at least one piezoresistor in said thinned region; treating said first, second and third wafers to make them hydrophylic; bringing said respective first surfaces of said first and second wafers into contact with each other and aligning said first and second wafers such that said first stop surface and said first contact surface are disposed substantially opposite each other within a first chamber defined by said first recessed region and said thinned region; bringing said second surface of said second wafer into contact with said first surface of said third wafer and aligning said first and second wafers such that said second stop surface and said second contact surface are disposed substantially opposite each other within a second chamber defined by said second recessed region and said thinned region; exposing said contacting and aligned first, second and third wafers to an oxidizing environment at a temperature of 400°C - 1200°C; wherein said prescribed depth of said first recessed region is selected such that said first contact surface and said first stop surface are disposed close enough together within said first chamber such that said first contact surface abuts against said first stop surface before said thinned region reaches said prescribed amount of deflection; and wherein said prescribed depth of said second recessed region is selected such that said second contact surface and said second stop surface are disposed close enough together within said second chamber such that said second contact surface abuts against said second top surface before said thinned region reaches said prescribed amount of deflection.

Claim 49

An electromechanical sensor produced according to a process comprising the steps of: forming a first shallow first recessed region in a first surface of a first semiconductor wafer such that said first recessed region has a prescribed depth and includes a first stop surface; forming a thinned region in a second semiconductor wafer such that said thinned region can withstand at least a prescribed amount of deflection without sustaining damage, said thinned region including a first contact surface on a first surface of said second semiconductor wafer and including a second contact surface on a second surface of said second semiconductor wafer; forming a shallow second recessed region in a first surface of a third semiconductor wafer such that said second recessed region has a prescribed depth and includes a second stop surface; forming at least one piezoresistor in said thinned region; treating said first, second and third wafers to make them hydrophylic; bringing said respective first surfaces of said first and second wafers into contact with each other and aligning said first and second wafers such that said first stop surface and said first contact surface are disposed substantially opposite each other within a first chamber defined by said first recessed region and said thinned region; bringing said second surface of said second wafer into contact with said first surface of said third wafer and aligning said first and second wafers such that said second stop surface and said second contact surface are disposed substantially opposite each other within a second chamber defined by said second recessed region and said thinned region; exposing said contacting and aligned first, second and third wafers to an oxidizing environment at a temperature of 400°C - 1200°C; wherein said prescribed depth of said first recessed region is selected such that said first contact surface and said first stop surface are disposed close enough together within said first chamber such that said first contact surface abuts against said first stop surface before said thinned region reaches said prescribed amount of deflection; and wherein said prescribed depth of said second recessed region is selected such that said second contact surface and said second stop surface are disposed close enough together within said second chamber such that said second contact surface abuts against said second top surface before said thinned region reaches said prescribed amount of deflection.

Claim 50

The sensor of Claims 39, 40 or 41 wherein the process further includes the step of forming a plurality of upstanding members in said first contact surface.

Claim 51

The sensor of Claims 39, 40 or 41 wherein the process further includes the step of forming a plurality of upstanding members in said first stop surface.

Claim 52

The sensor of Claim 41 wherein the process further includes the step of forming a plurality of upstanding members in said second contact surface.

Claim 53

The sensor of Claim 41 wherein the process further includes the step of forming a plurality of upstanding members in said second stop surface.