Stable thin film oxide standard
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorChin-Te Huang
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Abstract
A stable silicon oxide film for use as a thickness reference is prepared by oxidizing a silicon wafer, having a smooth surface, under carefully controlled conditions thereby growing a film of known thickness and refractive index. This is followed by the deposition of a layer of silicon nitride over said oxide film. The resulting structure may then be used as a reference standard when ellipsometry is routinely employed for measuring the thickness of, for example, gate oxides in field effect devices. It has been found that the thickness of the reference layer remains stable over extended time periods without the need for frequent cleaning.
Claims8
A thin film thickness standard, comprising:
- a substrate having an upper surface, with a micro-roughness value that is less than about 2 Angstroms, on which said thin film lies;
- and
- a layer of silicon nitride on said thin film.
A stable oxide thickness standard for use elipsometry, comprising:
- a silicon wafer having an upper surface with a micro-roughness value that is less than about 2 Angstroms;
- a layer of silicon oxide on said upper surface;
- and
- a layer of silicon oxide nitride on said layer of silicon oxide.
Dependencies are inferred from the claim text.