Illumination optical element for projection lithography

US10948828B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Stig Bieling · Aalen, DE
• Markus Deguenther · Aalen, DE

Key dates

• Filing date: Jul 9, 2020
• Grant date: Mar 16, 2021
• Expiry date: Jul 9, 2040

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/7015
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An illumination optical unit for projection lithography serves to illuminate an object field along an illumination light beam path. The illumination optical unit includes an optical rod with end-side entrance and exit areas. The optical rod is designed in such a way that illumination light is mixed and homogenized at lateral walls of the optical rod by multiple instances of total internal reflection. An optical rod illumination specification element is disposed upstream of the optical rod in the illumination light beam path and serves to specify an illumination of the entrance area with a distribution, specified over the entrance area, of an illumination intensity and, simultaneously, an illumination angle distribution. The specified illumination intensity distribution deviates from a homogeneous distribution over the entrance area. This can result in an illumination optical unit including an optical rod, in which a specified illumination setting can be set with lower illumination light losses.