Particle cleaning of optical elements for microlithography

US8477285B2 · kind B2 · utility

Assignees

• Carl Zeiss SMT GmbH · DE
• ASML NETHERLANDS B.V. · NL

Inventors

• Dirk Heinrich Ehm · Beckingen, DE
• Arnoldus Jan Storm · Delft, NL
• Johannes Hubertus Josephina Moors · Roosteren, NL
• Almut Czap · Aalen, DE
• Mona Nagel · Aalen, DE
• Jacques Cor Johan Van Der Donck · Alphen aan den Rijn, NL
• Jetske Karina Stortelder · The Hague, NL
• Marijn Sandtke · Delfgauw, NL
• Maria Isabel Catalina Caballero · The Hague, NL
• Luigi Scaccabarozzi · Valkenswaard, NL

Key dates

• Filing date: Dec 20, 2010
• Grant date: Jul 2, 2013
• Expiry date: Sep 15, 2031

Classification

• Technology area (CPC G): Physics
• CPC primary: G21K1/062
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An optical assembly is mounted in a projection exposure apparatus (101) for EUV microlithography and includes at least one vacuum chamber (70, 71, 68a), at least one optical element (6, 7; 65, 66; 63) arranged in the vacuum chamber (70, 71, 68a), the optical element (6, 7; 65, 66; 63) having an optical surface (18) arranged to be impinged upon by a useful beam bundle (3) of the projection exposure apparatus (101), and a cleaning device (72) configured to clean the optical surface (18). The cleaning device (72) is configured to perform particle cleaning of the optical surface (18) at a gas pressure within the vacuum chamber (70,71, 68a) which is higher than a vacuum pressure (po) for performing an exposure operation with the projection exposure apparatus (101). As a result, optical elements having respective optical surfaces arranged to be impinged upon by a useful beam bundle can be cleaned reliably of foreign particles.