Patent Number: 7,787,177

Title: High-NA projection objective with aspheric lens surfaces

Abstract: A projection objective for imaging a pattern provided in an object surface onto an image surface of the projection objective has an object-side imaging subsystem for creating a final intermediate image closest to the image surface from radiation coming from the object surface and an image-side imaging subsystem for directly imaging the final intermediate image onto the image surface. The image-side imaging subsystem includes at least one aspheric primary correcting lens having an aspheric primary correcting surface. The object-side imaging subsystem includes a secondary correcting group having at least one secondary correcting lens having an aspheric secondary correcting surface. Conditions involving maximum incidence angles and subaperture offsets at the correcting surfaces are given which should be observed to obtain sufficient aberration correction at very high image-side numerical apertures NA.

Inventors: Schuster; Karl-Heinz (Koenigsbronn, DE)

Assignee: Carl Zeiss SMT AG

International Classification: G02B 23/24 (20060101)

Expiration Date: 8/31/12018