Nikon Corporation

Ayako Sugaya

Masahiro Nakagawa

Tadashi Nagayama

Masashi Tanaka

Koichiro Komatsu

Position detectors are disclosed for reliable, high-accuracy detection of alignment marks on a wafer, including alignment marks consisting of small phase steps. The position detector comprises a phase plate located conjugate to an aperture stop. The phase plate produces a phase shift between the undiffracted light flux from the alignment marks and the diffracted light flux and a phase-contrast image is of the alignment marks is formed. The phase plate is switchable or insertable so that a bright-field image is also obtainable. Bright-field images and phase-contrast images are directly viewable or are received by one or more image sensor. A signal processor receives image signals from the image sensors and determines the position of the alignment marks. The sensor then provides a position signal that is used to move the wafer and reticle into alignment.

Position detector and microlithography apparatus comprising same

Position-detection apparatus (alignment sensors) are disclosed for determining the position of an object (e.g., wafer, bearing a position-detection mark) as required in microlithography processes for manufacturing semiconductor devices and displays. The apparatus comprises an irradiation optical system, a condenser optical system, a first photoelectric detector, a fiducial body bearing a fiducial mark, a combining optical system, a second photoelectric detector, and a processor. The position-detection and fiducial marks are illuminated with coherent illumination light from the irradiation optical system. Light diffracted from the marks is condensed by the condenser optical system. The first photoelectric detector receives the condensed diffracted light and produces first electrical signals. The combining optical system receives the diffracted light from the fiducial mark. The second photoelectric detector receives multiple diffracted light beams from the fiducial mark and produces second electrical signals. From the electrical signals, the processor determines the position of the position-detection mark relative to the fiducial mark.

Position detection apparatus and aligner comprising same

A wafer is brought into focus with a projection optical system, and a wafer mark on the wafer is also brought into focus with an off-axis alignment sensor highly accurately according to an automatic focusing process. First, a deviation of the surface of the wafer from an image plane of the projection optical system is measured by an oblique-incidence main AF sensor. For measuring the position of the wafer mark with an imaging device of an alignment system, part of a focusing ray of light from the wafer passes through an optical system, which is not telecentric, composed of an AF relay system and a half beam shield plate, and is detected by the imaging device, whereupon an image of a focusing mark projected onto the wafer is formed on the imaging device. The position of the image of the focusing mark on the imaging device is calibrated on the basis of the deviation which has been measured by the oblique-incidence main AF sensor.

Method and apparatus for alignment with a substrate, using coma

The present invention relates to inspection apparatus and method in which, based on images under a plurality of focus conditions formed by way of an optical system to be inspected, namely, using images under a plurality of defocal conditions, tendency in positional change or change of asymmetry between the images is calculated so as to specify at least one of aberration condition and optical adjustment condition of the optical system to be inspected as well as to exposure apparatuses and overlay accuracy measurement apparatuses provided with the inspection apparatus. In addition, the present invention relates to an image-forming optical system suitable to an alignment apparatus which is applicable to the exposure apparatuses. This image-forming optical system comprises a correction optical system for intentionally generating asymmetric aberration or symmetric aberration in the image-forming optical system and a decentering mechanism for decentering the correction optical system to cancel asymmetric aberration or symmetric aberration in the image-forming optical system.

Inspection apparatus and method for optical system, exposure apparatus

In a position detecting apparatus, according to this invention, a convexly and concavely patterned wafer mark is imaged on an image pickup surface via an imaging optical system, and the image on the image pickup surface is detected. The position detecting apparatus defocuses the average surface of the wafer mark from the optimum focusing surface depending on the pitch and difference in level of the wafer mark, etc., in the direction of the optical axis of the imaging optical system, and varies an illumination .sigma. value definded as the ratio of the numerical aperture of the illumination optical system and the numerical aperture of the imaging optical system. Then the position detecting apparatus provides lights from the wafer mark to the image pickup surface with rotation-symmetric wave aberration to allow the resulting image to have the highest contrast for positional detection.

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Kawasaki, Japan

Ayako Sugaya