This new technique is a variation on lateral solid phase epitaxy in which the growth of the epitaxial layer proceeds through a "tunnel" in the oxide.
To fabricate this structure, it is necessary to:
- Grow oxide on standard Si wafers
- Etch holes through to substrate
- Selectively grow epitaxial Si in thickness equal to oxide
- Deposit sacrificial amorphous Si layer
- Etch to define tunnel edges
- Deposit capping SiO2 layer
- Etch capping layer to define gas windows
- Remove amorphous Si with gaseous HCl etch
- Grow epitaxial Si in cavity
Investigators at NEC have fabricated SOI layers in this manner which they claim have excellent crystallinity and electrical characteristics suitable for device fabrication. Other possible applications for this technology could be in vertical transistors, interconnection fabrication, and micromachining.
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