Methods and scatterometers, lithographic systems, and lithographic processing cells

Patent metadata

Field	Value
Publication number	US-8994944-B2
Application number	US-201414149723-A
Country	US
Kind code	B2
Filing date	Jan 7, 2014
Priority date	Jul 31, 2009
Publication date	Mar 31, 2015
Grant date	Mar 31, 2015

Abstract

In a method of determining the focus of a lithographic apparatus used in a lithographic process on a substrate, the lithographic process is used to form a structure on the substrate, the structure having at least one feature which has an asymmetry in the printed profile which varies as a function of the focus of the lithographic apparatus on the substrate. A first image of the periodic structure is formed and detected while illuminating the structure with a first beam of radiation. The first image is formed using a first part of non-zero order diffracted radiation. A second image of the periodic structure is formed and detected while illuminating the structure with a second beam of radiation. The second image is formed using a second part of the non-zero order diffracted radiation which is symmetrically opposite to the first part in a diffraction spectrum. The ratio of the intensities of the measured first and second portions of the spectra is determined and used to determine the asymmetry in the profile of the periodic structure and/or to provide an indication of the focus on the substrate. In the same instrument, an intensity variation across the detected portion is determined as a measure of process-induced variation across the structure. A region of the structure with unwanted process variation can be identified and excluded from a measurement of the structure.

First claim

What is claimed is:

1. A method of detecting process-induced variation in a structure on a substrate, the method comprising:
directing a beam of radiation onto the substrate so as to illuminate the structure, an area of the structure being less than an area of the beam of radiation;
forming an image of the structure using only one selected diffraction order of radiation diffracted by the substrate;
detecting a portion of the formed image;
determining an intensity variation a…

Assignees

• Asml Netherlands Bv

Inventors

• Cramer Hugo Augustinus Joseph
• Den Boef Arie Jeffrey
• Megens Henricus Johannes Lambertus
• Smilde Hendrik Jan Hidde
• Schellekens Adrianus Johannes Hendrikus
• Kubis Michael

Classifications

• G03F7/70191

  Physics · mapped topic

• G01N21/88

  Physics · mapped topic

• G03F7/70641 Primary

  Physics · mapped topic

• G03F7/70633

  Physics · mapped topic

• G03F7/70625

  Physics · mapped topic