Nikon Corporation

Nikon Corooration

Eiji Takane

Shigeru Hirukawa

Nobuyuki Irie

Yoshichika Iwamoto

Ryoichi Kaneko

A method of aligning each of a plurality of processing areas regularly aligned on a substrate according to designed alignment coordinates to a predetermined reference position in a static coordinate system for defining the moving position of the substrate is disclosed. The coordinate positions, on the static coordinate system, of at least three processing areas selected in advance as specific processing areas from the plurality of processing areas are measured. The coordinate positions, on the static coordinate system, of the plurality of processing areas on the substrate are determined by weighting the coordinate positions, on the static coordinate system, of the at least three specific processing areas according to the distances between a processing area of interest and each of the at least three specific processing areas in units of processing areas on the substrate, and executing a statistic calculation using the plurality of weighted coordinate positions.

Alignment method and alignment apparatus with a statistic calculation

In order to measure inclination of a leveling plane with respect to the best image forming plane rapidly at a high accuracy without using a special super-flat wafer, the images of five focus measuring marks are exposed on shot areas partially overlapping with each other, on one hand, in a first exposure area when a focal position is made to coincide with a first focal position by operating a leveling mechanism and, on the other hand, in each of exposure areas when the focal positions are changed gradually. The best focal position is obtained by using an average of the mark lengths of the images of the marks as the mark lengths of the images of marks of measuring points at the upper left corners of the focal positions.

Method of measuring a leveling plane

Disclosed is a method of calculating the best focus position of a projection optical system by arranging a photosensitive substrate in the best focus position of a projection optical system, projecting measuring mark images in a plurality of focus positions on the photosensitive substrate in an optical-axis direction of the projection optical system to projection-expose mask patterns and thus obtaining the best focus position from a relationship between each of the focus positions and the measuring mark image corresponding thereto. The method comprises a first step of approximating a size of the measuring mark image with an nth-order or larger (n is an integer of 2 or larger) function relative to the focus position by a statistical operation. The method also comprises a second step of obtaining a tentative best focus position from the approximated function and a third step of calculating a weight corresponding to each of the plurality of measuring mark images on the basis of a difference between the tentative best focus position and each of the plurality of focus positions. The method further comprises a fourth step of approximating a size of the measuring mark image with an nth-order or smaller function relative to the focus position by a statistical operation to minimize a sum, relative to the focus position, of product of the weight obtained in the third step by a square of a difference between the nth-order or smaller function relative to the focus position and the size of the measuring mark image corresponding thereto and a fifth step of obtaining the best focus position of the projection optical system from the nth-order or smaller function obtained in the fourth step.

Growing community of inventors

Tokyo, Japan

Eiji Takane