Semiconductor device and method of fabrication

a semiconductor device comprising,

• a base semiconductor substrate,
• means defining a closed peripheral cavity in the substrate extending in frame configuration,
• an insulating layer in the cavity,
• a layer of polysilicon disposed over the insulating layer to substantially fill the cavity and provide structural support,
• an epitaxy layer disposed over the surface of the substrate as well as over the insulating and polysilicon layers,
• a second insulating layer having windows defined therein for enabling ohmic contact with the epitaxy layer and substrate, respectively,
• and separate conductor leads to provide contact to the epitaxy layer and substrate respectively,
• said semiconductor substrate and epitaxy layer being oppositely doped to form a device region,
• said insulating layer in the cavity being non-reactant to the etching of the substrate while permitting etching of the substrate so as to enable exposure of the conductor leads,
• said conductor leads comprising beam leads that extend in opposite directions from the substrate,
• at least one of said beam leads having a major area thereof spaced by a minor area in comparison to the major area so as to space the major area from the device region to thus minimize parasitic capacitance.