Technique for producing small islands of silicon on insulator
OwnerLeonard Forbesinventor
Life of this patent
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Abstract
Using sub-micron technology, silicon on insulator (SOI) rows and islands are formed in a silicon substrate. Trenches are directionally-etched in the silicon substrate, leaving rows of silicon between the trenches. Silicon nitride is then deposited over the trenches, extending partly down the sides of the trenches. An isotropic chemical etch is then used to partially undercut narrow rows of silicon in the substrate. A subsequent oxidation step fully undercuts the rows of silicon, isolating the silicon rows from adjacent active areas. Devices, such as transistors for CMOS and DRAMs, are then formed in active areas, wherein the active areas are defmed on the silicon rows by LOCal Oxidation of Silicon (LOCOS).
Claims20
A method for manufacturing a silicon on insulator substrate, comprising the steps of:
- directionally etching a silicon substrate, to form a plurality of trenches between protruding silicon rows;
- forming a silicon nitride cap on the silicon rows, extending partway down the sides of the trenches;
- isotropically etching the trenches, to partially undercut the silicon rows;
- and
- oxidizing the substrate, to fully undercut the silicon rows.
A silicon on insulator structure, comprising:
- a plurality of silicon rows, having a width dimension of one micron or less, embedded in an oxidized substrate;
- and
- a plurality of oxide rows between the silicon rows.
A plurality of active areas on a semiconductor substrate, comprising:
- a plurality of isolated silicon active areas, having an area of one square micron or less, embedded in an oxidized substrate;
- and
- a plurality of oxide rows between the silicon active areas in one direction.
Dependencies are inferred from the claim text.