US 4,732,647 AGranted

Batch method of making miniature capacitive force transducers assembled in wafer form

OwnerHarry E. Aineinventor

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Abstract

A batch method for fabricating semiconductive capacitive force transducers is disclosed wherein a first wafer of silicon or fused silica is recessed by etching to define a array of force transducer structures, each including a deflectable portion supported from a surrounding frame portion. The first wafer is thermoelectrically bonded between a pair of glass or quartz plates, each plate having an array of electrode structures for capacitively sensing deflection of the individual force transducers. Each electrode structure includes a lead portion passing over the frame portio of the transducers and being spaced from the frame to provide a gas communication passageway through the frame to the capacitive gap between the electrode structure and the deflectable portion of each transducer. The composite assembled wafers are notched along cleave lines generally outlining the individual transducer structures. The notching along the cleave lines is preferably performed by sawing or scribing with the saw kerf or scribe lines extending only partially through the plates so as not to contaminate the individual transducer devices. The individual transducer structures are then cleaved from the composite wafer so as not to introduce contaminants into the individual transducers.

Claims9

Dependent claims

In a batch method for fabricating non-hermetically sealed force transducer structures, the steps of:

recessing a first wafer according to a pre-determined pattern to form an array of force transducer structures in said first wafer each of said force transducer structures having a deflectable portion which deflects in accordance with the force to be transduced;
bonding a second wafer to said first wafer, said second wafer having an array of electrode structures on a major face thereof disposed in overlaying relationship with said first wafer with the electrode structures facing the force transducer structures in said first wafer for electric interaction with the deflectable portions of said transducer structures;
said force transducer structures in said first wafer each including a frame portion surrounding and being connected to said deflectable portion which deflects in response to the force to be transduced;
said electrode structures of said array each including a planar electrode portion disposed overlaying the deflectable portion of said force transducer structures in non-electrical contact therewith and including a lead portion extending from said planar electrode portion across and in overlaying spaced apart relation with said frame portion of said transducer structures to define a gas communication passageway in the space between said lead portion and the overlayed frame portion across said frame and for making electrical contact to said planar electrode structure without electrically contacting said frame portion;
removing material from said second wafer to form cleave lines generally outlining individual ones of said frame portions of said first wafer with the cleave lines in said second wafer extending only partially through the thickness of said second wafer;
and
cleaving the bonded first and second wafers along said cleave lines to separate individual force transducer structures, one from the other in said array of structures, whereby said force transducer structures are assembled in wafer form and then cleaved from the assembled wafer to provide a batch method of fabricating said force transducer structures.

4 more elements

In a batch method for fabricating capacitive force transducer structures assembled in wafer form, the steps of:

recessing a first wafer in accordance with a pre-determined pattern to define an array of force transducer structures in said first wafer;
said recess defined force transducer structures in said first wafer each including a frame portion connected to and surrounding a deflectable structure portion which deflects in response to the force to be transduced;
bonding second and third wafers to opposite major faces of said first wafer to sandwich said first wafer containing said array of force transducer structures inbetween said second and third wafers;
each of said second and third wafers having an array of electrode structures on a major face thereof which is disposed facing said first wafer;
each of said electrode structures of said arrays including a planar electrode portion disposed overlaying said deflectable portion of said force transducer structures of said first wafer for capacitive electrical interaction with said deflectable portion and also including a narrower lead portion extending from said planar portion and across said frame portion in overlaying spaced apart relation therewith and terminating in contact pad portions outside said frame portion for making electrical contact to said planar electrode structure free of shorts to said frame portion with the space between the lead portion and the spaced frame defining a gas passageway communicating between the deflectable portion of said transducer structure and the exterior of said frame portion;
removing material from said second and third wafers to form cleave lines generally outlining individual ones of said frame portions of said first wafer with the cleave lines in said second and third wafers extending only partially through the thickness of said second and third wafers so that the gas communication passageways in the spaces inbetween the frame portions and the overlaying lead portions of said electrode structures are not directly exposed through the thickness of the second and third wafers to the surrounds of said second and third wafers;
and
cleaving the bonded first, second and third wafers along said cleave lines to separate individual force transducers one from the other in said array of transducers, whereby said force transducers are assembled in wafer form and cleaved from the assembled wafers to provide a batch method of fabricating said force transducers.

5 more elements

Dependencies are inferred from the claim text.