Lithographic focus and dose measurement using a 2-D target

摘要

In order to determine whether an exposure apparatus is outputting the correct dose of radiation and its projection system is focusing the radiation correctly, a test pattern is used on a mask for printing a specific marker onto a substrate. This marker is then measured by an inspection apparatus, such as a scatterometer, to determine whether there are errors in focus and dose and other related properties. The test pattern is configured such that changes in focus and dose may be easily determined by measuring the properties of a pattern that is exposed using the mask. The test pattern may be a 2D pattern where physical or geometric properties, e.g., pitch, are different in each of the two dimensions. The test pattern may also be a one-dimensional pattern made up of an array of structures in one dimension, the structures being made up of at least one substructure, the substructures reacting differently to focus and dose and giving rise to an exposed pattern from which focus and dose may be determined.

主权项

1. A method comprising:
printing a marker on a substrate using an exposure apparatus and a mask, the mask including a pattern for creating the marker, wherein the marker comprises a two-dimensional array of structures formed by repeated exposure of the pattern, such that the structures along an x direction of the two-dimensional array are sensitive to dose variations, but are not sensitive to focus variations, and the structures along a y direction of the two-dimensional array are sensitive to both dose and focus variations; and measuring a property of the substrate that has been exposed by the exposure apparatus and the mask, the measuring comprising:
projecting a radiation beam onto the marker on the substrate;detecting radiation reflected from the marker on the substrate; anddetermining, from the properties of the reflected radiation, at least one of the focus and the dose of the exposure apparatus.