High temperature layered silicon structures

Claim 1

A laminate for use as a high temperature pressure transducer, said laminate comprised of a silicon wafer oriented (100) and having a silicon gauge wafer film rich in boron laminated to one side thereof, said laminate obtained by the steps of (a) selecting a diaphragm wafer; (b) selecting a gauge wafer; (c) depositing in a first depositing step a boron rich layer on one surface of said gauge layer; the improvement characterized by (d) depositing in a second depositing step silicon dioxide on one surface of said diaphragm layer; (e) orienting said diaphragm wafer with said gauge wafer so that said boron rich layer is adjacent said silicon dioxide layer; (f) subjecting in a first subjecting step said wafers to temperature and pressure conditions sufficient to cause adhesion between said boron rich layer and said silicon dioxide layer; (g) said first subjecting step is carried out in a press first at a pressure at about two pounds per square inch for a time sufficient to elevate said temperature to an adhesion temperature above the melting temperature of said boron rich layer; (h) said first subjection step is carried out secondly by maintaining said elevated temperature for six hours at an elevated pressure within the range of between about above two and sixty pounds per square inch; (i) subjecting in a second subjecting step said oriented wafers to temperature conditions sufficient to simultaneously diffuse said boron rich layer into both said gauge wafer and said silicon dioxide layer on said diaphragm wafer; (j) removing a substantial portion of said gauge wafer from the surface thereof opposite said diaphragm wafer to provide a boron rich gauge wafer film; (k) said removing step including preferentially etching said gauge wafer to a uniform thickness; and (l) said uniform thickness is within the range of between about 5×10 19 and 1×10 20 atoms of boron per cubic centimeter of remaining gauge film.