FOCUSING METHOD, FOCUSING APPARATUS, EXPOSURE METHOD, AND DEVICE MANUFACTURING METHOD

摘要

A target object has an upper surface including a first surface and a second surface located below the first surface. A method of focusing an optical system includes: measuring a surface position of the first surface; measuring a surface position of the second surface; obtaining, based on a measurement results of the surface position of the first surface, an in-focus condition in which the optical system is focused on the first surface; obtaining information about a step amount between the first surface and the second surface based on the measurement results of the surface positions of the first surface and the second surface; and focusing the optical system on the second surface based on the in-focus condition and the information about the step amount.

主权项

1. A method of focusing an optical system on a second surface of a target object having an upper surface including a first surface and a second surface located below the first surface, comprising:
a first step of projecting light to the first surface at a first incident angle which forms a first angle with respect to a first direction parallel to an optical axis of the optical system, and receiving the light reflected by the first surface to measure a surface position of the first surface; a second step of projecting light to the second surface at a second incident angle which forms a second angle smaller than the first angle with respect to the first direction, and receiving the light reflected by the second surface to measure a surface position of the second surface; a third step of obtaining, based on a measurement result of the surface position of the first surface, an in-focus condition in which the optical system is focused on the first surface; a fourth step of obtaining information about a step amount between the first surface and the second surface based on the measurement result of the surface position of the first surface and a measurement result of the surface position of the second surface; and a fifth step of focusing the optical system on the second surface based on the in-focus condition and the information about the step amount.