Method of producing aspherical optical surfaces

US7540983B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Ernst-Dieter Knohl · Königsbronn, DE
• Andreas Frommeyer · Schwäbisch Gmünd, DE
• Hermann Schubert · Linz, AT

Key dates

• Filing date: Jul 8, 2004
• Grant date: Jun 2, 2009
• Expiry date: Sep 3, 2026

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S425/808
• WIPO field: Machine tools
• WIPO sector: Mechanical engineering

Abstract

In the case of a method of producing aspherical optical surfaces of optical elements (1), in particular for use in microlithography for producing semiconductor elements, the optical element (1) is ground for example in the form of a meniscus. In a first method step, the optical element (1) is introduced into a basic form (2), which has a spherical form bed and is being held at a distance over the form bed (3). After that, an intermediate medium (6) is introduced in the basic form (2) between the optical element (1) and the form bed (3) and, subsequently the optical element (1) being removed together with the intermediate medium (6) from the basic form. Then, the spherical form bed (3) of the basic form (2) or a second basic form is transformed into an aspherical form bed (3′) computationally determined in advance. The optical element (1) is then re-introduced with the intermediate medium (6) into the basic form (2) or the second basic form, the intermediate medium (6) being sucked against the form bed (3′) by applying a vacuum. Subsequently, the optical element (1) deformed by the vacuum applied is spherically machined on a surface (7). Finally, after removing the vacuum, the surfa…