Method for fabricating a silicon force transducer

Claim 1

A method for fabricating a force transducer having parallel plates to measure the change in capacitance therebetween in response to an applied force wherein the movement of the plates is rectilinear in response to the applied force, said method comprising the steps of: anisotropically etching a pair of parallel grooves along a top planar surface of a silicon substrate forming a first plate between said parallel grooves; doping said top planar surface to form a highly conductive region along said top planar surface; forming a substantially uniform layer of a selectively etchable material over said grooved top planar surface; forming a substantially uniform layer of doped silicon over said layer of selectively etchable material following the contour of said grooved top planar surface to define a pair of convolutions opposite said pair of grooves and a second plate between said pair of convolutions; etching a pair of openings through said silicon layer such that said second plate is connected to said silicon layer only through said pair of convolutions; applying a selective etchant through said pair of openings etching only said selectively etchable layer to suspend said second plate and said pair of convolutions over said top planar surface; and coupling detecting circuitry to both said silicon layer and said substrate to detect capacitive changes between said first plate and said second plate in response to the applied force.

Claim 2

A method for fabricating a force transducer having parallel plates to measure the change in capacitance therebetween in response to an applied force wherein the movement of the plates is rectilinear in response to the applied force, said method comprising the steps of: anisotropically etching a pair of parallel grooves along a top planar surface of a silicon substrate forming a first plate between said parallel grooves; doping said top planar surface to form a highly conductive region along said top planar surface; forming a substantially uniform layer of a selectively etchable material over said grooved top planar surface; forming a substantially uniform layer of doped silicon over said layer of selectively etchable material following the contour of said grooved top planar surface to define a pair of convolutions opposite said pair of grooves and a second plate between said pair of convolutions; etching a pair of openings through said silicon layer such that said second plate is connected to said silicon layer only through said pair of convolutions; applying a selective etchant through said pair of openings etching only said selectively etchable layer to suspend said second plate and said pair of convolutions over said top planar surface; and coupling detecting circuitry to both said silicon layer and said substrate to detect capacitive changes between said first plate and said second plate in response to the applied force.

Claim 9

A method for fabricating a force transducer having parallel plates to measure the change in capacitance therebetween in response to an applied force wherein the movement of the plates is rectilinear in response to the applied force, said method comprising the steps of: preparing a silicon substrate having nominal crystalline planes and a top planar surface substantially parallel to said nominal planes; anisotropically etching a pair of V-shaped parallel grooves along said top planar surface forming a first plate between said parallel grooves, each of said V-shaped grooves having side walls lying substantially in the {111} monocrystalline planes; doping said top planar surface to form a conductor region along said top planar surface; forming a substantially uniform layer of a selectively etchable material over said grooved top planar surface; forming a substantially uniform layer of doped silicon over said layer of selectively etchable material following the contour of said grooved top planar surface to define a pair of V-shaped members opposite said pair of grooves and a second plate between said pair of V-shaped members; etching a pair of openings through said silicon layer such that said second plate is connected to said silicon layer only through said pair of V-shaped members; applying a selective etchant through said pair of openings etching only said selectively etchable layer to suspend said second plate and said pair of V-shaped members over said top planar surface; and coupling detecting circuitry to both said silicon layer and said substrate to detect capacitive changes between said first plate and said second plate in response to the applied force.

Claim 10

A method for fabricating a force transducer having parallel plates to measure the change in capacitance therebetween in response to an applied force wherein the movement of the plates is rectilinear in response to the applied force, said method comprising the steps of: preparing a silicon substrate having nominal crystalline planes and a top planar surface substantially parallel to said nominal planes; anisotropically etching a pair of V-shaped parallel grooves along said top planar surface forming a first plate between said parallel grooves, each of said V-shaped grooves having side walls lying substantially in the {111} monocrystalline planes; doping said top planar surface to form a conductor region along said top planar surface; forming a substantially uniform layer of a selectively etchable material over said grooved top planar surface; forming a substantially uniform layer of doped silicon over said layer of selectively etchable material following the contour of said grooved top planar surface to define a pair of V-shaped members opposite said pair of grooves and a second plate between said pair of V-shaped members; etching a pair of openings through said silicon layer such that said second plate is connected to said silicon layer only through said pair of V-shaped members; applying a selective etchant through said pair of openings etching only said selectively etchable layer to suspend said second plate and said pair of V-shaped members over said top planar surface; and coupling detecting circuitry to both said silicon layer and said substrate to detect capacitive changes between said first plate and said second plate in response to the applied force.

Claim 15

A method for fabricating a force transducer having parallel plates to measure the change in capacitance therebetween in response to an applied force wherein the movement of the plates is rectilinear in response to the applied force, said method comprising the steps of: preparing a n-silicon substrate having nominal crystalline planes and a top planar surface substantially parallel to said nominal planes; anisotropically etching a pair of V-shaped parallel grooves along said top planar surface forming a first plate between said parallel grooves, each of said V-shaped grooves having side walls lying substantially in the {111} monocrystalline planes; doping said first plate to form an n-type conductor region along said first plate; forming a p-epitaxial silicon layer over said grooved top planar surface; forming an n-epitaxial layer of doped silicon over said p-epitaxial layer following the contour of said grooved top planar surface to define a pair of V-shaped members opposite said pair of grooves and a second plate between said pair of V-shaped members; etching an opening through said n-epitaxial layer such that said second plate is connected to said n-epitaxial layer only through said pair of V-shaped members; applying a positive voltage to both said n-silicon substrate and said n-epitaxial layer with respect to said p-epitaxial layer; anisotropically etching said p-epitaxial layer to suspend said second plate and said pair of V-shaped members over said top planar surface; and coupling electronic detecting to both said first capacitive plate and said second capacitive plate to detect capacitive changes between said plates in response to the applied force.

Claim 16

A method for fabricating a force transducer having parallel plates to measure the change in capacitance therebetween in response to an applied force wherein the movement of the plates is rectilinear in response to the applied force, said method comprising the steps of: preparing a n-silicon substrate having nominal crystalline planes and a top planar surface substantially parallel to said nominal planes; anisotropically etching a pair of V-shaped parallel grooves along said top planar surface forming a first plate between said parallel grooves, each of said V-shaped grooves having side walls lying substantially in the {111} monocrystalline planes; doping said first plate to form an n-type conductor region along said first plate; forming a p-epitaxial silicon layer over said grooved top planar surface; forming an n-epitaxial layer of doped silicon over said p-epitaxial layer following the contour of said grooved top planar surface to define a pair of V-shaped members opposite said pair of grooves and a second plate between said pair of V-shaped members; etching an opening through said n-epitaxial layer such that said second plate is connected to said n-epitaxial layer only through said pair of V-shaped members; applying a positive voltage to both said n-silicon substrate and said n-epitaxial layer with respect to said p-epitaxial layer; anisotropically etching said p-epitaxial layer to suspend said second plate and said pair of V-shaped members over said top planar surface; and coupling electronic detecting to both said first capacitive plate and said second capacitive plate to detect capacitive changes between said plates in response to the applied force.