Lithographic apparatus, device manufacturing method, and...

Details Lithographic apparatus, device manufacturing method, and... Lithographic apparatus, device manufacturing method, and...

2005-11-01

2005-11-01

Mathews, Alan (Department: 2851)

Photocopying

Projection printing and copying cameras

Step and repeat

C355S071000, C356S400000, C356S401000, C356S508000, C356S509000, C430S022000

Reexamination Certificate

active

06961116

ABSTRACT:
An alignment system uses a self-referencing interferometer that produces two overlapping and relatively rotated images of an alignment markers. Detectors detect intensities in a pupil plane where Fourier transforms of the images are caused to interfere. The positional information is derived from the phase difference between diffraction orders of the two images which manifests as intensity variations in the interfered orders. Asymmetry can also be measured by measuring intensities at two positions either side of a diffraction order.

REFERENCES:
patent: 4687332 (1987-08-01), Bareket
patent: 6628406 (2003-09-01), Kreuzer
patent: 2002/0037460 (2002-03-01), Takahashi
patent: 1 148 390 (2001-10-01), None
Moel et al., “Novel on-axis interferometric alignment method with sub-10 nm precision,”J. Vac. Sci. Technol. B. 11(6):2191-2194 (1993).
Ota et al., “New Alignment Sensors for Wafer Stepper,”SPIE Optical/Laser Microlithography IV: 1463:304-314 (1991).

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