Back sealing of silicon wafers
AssigneeAmerican Telephone and Telegraph Company, AT&T Technologies, Inc.
InventorJeffrey T. Koze
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Abstract
Sealing the backside of a semiconductor wafer prevents evaporation of the dopant (typically boron) when an epitaxial layer is grown on the front (active) side, thereby preventing autodoping of the epitaxial layer with excess dopant. The present technique deposits an oxide layer during the ramp-up of the furnace that also deposits the nitride cap, thereby avoiding an extra process step. It also avoids the higher temperatures required for the prior-art technique of growing the oxide layer, resulting in lower oxygen precipitation due to the capping process and a greater yield of usable wafers.
Claims14
A method of making a solid state device by steps comprising capping a back side of a semiconductor wafer in preparation for forming an epitaxial layer of a semiconductor material on the front side of said wafer,
- characterized in that said capping is accomplished by steps comprising:
- introducing said wafer into a furnace;
- increasing the temperature in said furnace while introducing a source gas comprising a silicon compound and a source of oxygen into said furnace, thereby depositing silicon dioxide onto said wafer during said increasing the temperature;
- maintaining said furnace at an elevated temperature and introducing a source of silicon and a source of nitrogen into said furnace, thereby depositing silicon nitride onto said silicon dioxide;
- and removing said wafer from said furnace.
Dependencies are inferred from the claim text.