"Method of patterning sub-0.25 lambda line features with high transmission, ""attenuated"" phase shift masks"

US6312854A · kind A · utility

Assignee

• ASML Masktools Netherlands B.V. · NL

Inventors

• J. Fung Chen · Cupertino, US
• Roger Caldwell · Tullahoma, US
• Tom Laidig · Richmond, US
• Kurt E. Wampler · Sunnyvale, US

Key dates

• Filing date: Mar 16, 1999
• Grant date: Nov 6, 2001
• Expiry date: Mar 16, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F1/36
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method for making a mask for optically transferring a lithographic pattern corresponding to an integrated circuit from the mask onto a semiconductor substrate by use of an optical exposure tool. The method includes the steps of de-composing the existing mask patterns into arrays of "imaging elements." The imaging elements are .pi.-phase shifted and are separated by non-phase shifting and sub-resolution elements referred to as anti-scattering bars (ASBs). In essence, the ASBs are utilized to de-compose the larger-than-minimum-width mask features to form "halftone-like" imaging patterns. The placement of the ASBs and the width thereof are such that none of the .pi.-phase shifting elements are individually resolvable, but together they form patterns substantially similar to the intended mask features.