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US 7,564,556 B2Granted
Method and apparatus for lens contamination control
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsKeh-Wen Chang, Jun-Ren Chen
Life of this patent
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Abstract
The present disclosure provides a method for measuring lens contamination in a lithography apparatus. The method includes imaging an asymmetric pattern utilizing a lens system and measuring an alignment offset of the asymmetric pattern associated with the lens system. A contamination of the lens system is determined by comparing the alignment offset to a reference value.
Claims19
A method for measuring lens contamination in a lithography apparatus, comprising:
- imaging an asymmetric pattern utilizing a lens system;
- measuring an alignment offset of the asymmetric pattern, the alignment offset being associated with the lens system;
- and
- determining defects of the lens system by comparing the alignment offset to a reference value,
- wherein imaging the asymmetric pattern comprises introducing stray light from defects of the lens system, the stray light narrowing the alignment offset relative to the reference value.
2 more elements
A method for measuring lens contamination in a lithography apparatus, comprising:
- providing a mask having an asymmetric pattern utilizable by a focus-calibration-using-alignment (FOCAL) technique;
- imaging the asymmetric pattern to a substrate using a lens system;
- measuring an alignment offset of the asymmetric pattern;
- and
- identifying defects of the lens system using the alignment offset by comparing the alignment offset to a reference value,
- wherein imaging the asymmetric pattern comprises introducing stray light from defects of the lens system, the stray light narrowing the alignment offset relative to the reference value.
3 more elements
A lithography apparatus, comprising:
- a lens system;
- a substrate stage configured to secure a substrate for receiving a radiation energy through the lens system, and designed operable to support relative movement between the substrate and the lens system;
- and
- a detection system designed operable to
- form an asymmetric pattern on the substrate using an imaging source;
- measure an alignment offset of the asymmetric pattern;
- calibrate the focus of the lens system using the alignment offset;
- and
- determine contamination of the lens system by
- determining defects of the lens system by comparing the alignment offset to a reference value,
- wherein operable to form an asymmetric pattern comprises introducing stray light from defects of the lens system, the stray light narrowing the alignment offset relative to the reference value.
8 more elements
Dependencies are inferred from the claim text.