Photolithographic mask and methods for producing a structure and of exposing a wafer in a projection apparatus

US6838216B2 · kind B2 · utility

Assignee

• Infineon Technologies AG · DE

Inventors

• Uwe Griesinger · Hersbruck, DE
• Mario Hennig · Dresden, DE
• Jurgen Knobloch · Ruderatshofen, DE
• Rainer Pforr · Dresden, DE
• Manuel Vorwerk · Dresden, DE

Key dates

• Filing date: May 14, 2003
• Grant date: Jan 4, 2005
• Expiry date: May 14, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70433
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Auxiliary openings are assigned to openings on a mask to be transferred to a wafer. These auxiliary openings have a phase-shifting property, preferably between 160° and 200° with respect to the openings, and a cross section lying below the limiting dimension for the printing of the projection apparatus, so that the auxiliary openings themselves are not printed onto the wafer. However, the auxiliary openings do enhance the contrast of the aerial image, in particular of an associated, isolated or semi-isolated opening on the wafer. The auxiliary openings may have a distance from the opening that lies above the resolution limit of the projection apparatus but that is less than the coherence length of the light used for the projection. A phase-related utilization of the optical proximity effect results, which can produce elliptical structures from square openings on the mask when the auxiliary openings are disposed in the preferential direction.