Method of compensating the proximity effect in electron beam projection systems

US4426584A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Harald Bohlen · Eppelheim, DE
• Helmut Engelke · Altdorf, DE
• Johann Greschner · Neckartenzlingen, DE
• Peter Nehmiz · Stuttgart, DE

Key dates

• Filing date: Jun 3, 1981
• Grant date: Jan 17, 1984
• Expiry date: Jun 3, 2001

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J2237/31769
• WIPO field: Micro-structural and nano-technology
• WIPO sector: Chemistry

Abstract

For compensating scattering losses of electrons in photoresists (proximity effect) which influence electron beam lithography by altering the pattern geometry it is suggested to expose selected partial areas of a pattern to an additional irradiation dosage in a second exposure step. For that purpose, a specific mask with corresponding correction openings can be used which is applied with the same, or with a different electron beam intensity. In a particularly advantageous manner the correction of the proximity effect can be achieved when complementary masks are used; the correction openings for the partial areas of the one complementary mask are arranged in the other complementary mask. The proximity effect is then corrected without an additional exposure step. For measuring the proximity effect a photo-optical process is suggested where line patterns with decreasing ridge width in the photoresist are defined through electron beam projection, and where the developing process of the photoresist is discontinued prematurely. The ridge edges which in the presence of the proximity effect are asymmetrical can be easily detected under the microscope.