Abstract Islands of dielectrically isolated monocrystalline silicon, fabricated in a polycrystalline base, are first produced. Device fabrication and beam lead interconnection follow. Thereafter the planar top surface is covered with an etch-resistant wax and the polycrystalline base is removed by etching. In another embodiment, SiO2 is grown on a grooved, monocrystalline silicon slice, and polycrystalline silicon is deposited thereover. The slice is then lapped down on the top side so that the polycrystalline silicon and SiO2 form barriers. Second side is lapped after devices are fabricated and after beam leads are formed. Active devices and beam leads are fabricated on one surface, and the polycrystalline material is lapped and etched away from the back. In either case, the remaining structure is an air-isolated beam lead device.
The method as claimed in claim 1 wherein said slice is silicon, said oxide films are silicon dioxide and said polycrystalline material is epitaxial silicon.
Claim 2
Dependent Claim
60 words
The method as claimed in claim 1 wherein said deposition of polycrystalline material comprises (a) depositing said material over said entire one surface as well as said grooves, (b) lapping said one surface to remove all said polycrystalline material except that in said grooves and to expose said one surface, and (c) regrowing said oxide film on said one surface.
Claim 3
Dependent Claim
29 words
The process as claimed in claim 1, wherein, prior to said lapping step, said one surface is covered with an etchresistant material and is affixed to a mounting plate.
Claim 4
Dependent Claim
34 words
The process as claimed in claim 1, wherein said masking is patterned so that only polycrystalline material underlying beam lead terminations is removed in said etching step, thereby producing a beam lead dielectrically-isolated device.
Claim 5
Dependent Claim
31 words
The process as claimed in claim 1, wherein said masking is patterned so that all said polycrystalline material is removed in said etching step, thereby producing an air-isolated beam lead device.
Claim 6
Dependent Claim
62 words
ThE process as claimed in claim 1, wherein said groove forming step and said oxide growth step comprise: a. initially growing an oxide film on said one surface; b. forming openings in said oxide film over desired groove areas; c. etching said slice to form said grooves beneath said opening; and d. growing an oxide film on the surfaces of said grooves.