Method for eliminating residual oxygen impurities from silicon wafers pulled from a crucible
AssigneeInfineon Technologies AG
InventorsHelmut Strack, Jens-Peer Stengl
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Abstract
Residual oxygen impurities are eliminated from silicon wafers pulled from a crucible (Czochralski silicon). A multitude of trenches are etched into the back side of the crucible-pulled silicon wafer and the wafer is subsequently heat-treated at about 1100° C. The very large surface area at the front side of the silicon wafer allows oxygen impurities to diffuse out effectively. After the diffusion has been carried out, the trenches are filled with heavily doped polysilicon without leaving gaps.
Claims10
A method for eliminating residual oxygen impurities from crucible-pulled silicon wafers, which comprises the following steps:
- providing a crucible-pulled silicon wafer with a front side for active regions and a back side;
- etching a multitude of trenches into the back side of the silicon wafer;
- subsequently heating the silicon wafer to a temperature of about 1100° C. in one of a vacuum and an inert gas atmosphere and causing residual oxygen impurities to diffuse out of the silicon wafer for eliminating the residual oxygen impurities from the silicon wafer;
- subsequently filling the trenches with heavily doped polysilicon;
- and
- applying a metallization to the back side of the silicon wafer.
Dependencies are inferred from the claim text.