Method and apparatus for compensation of beam property drifts detected by measurement systems outside of an excimer laser

US6822977B1 · kind B1 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Uwe Stamm · Göttingen, DE
• Hans-Stephan Albrecht · Göttingen, DE
• Gunter Nowinski · Unterwellenborn, DE

Key dates

• Filing date: Jun 6, 2002
• Grant date: Nov 23, 2004
• Expiry date: Feb 2, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/134
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A lithography laser system for incorporating with a semiconductor processing system includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, multiple electrodes within the discharge chamber and connected with a discharge circuit for energizing the laser gas, a resonator including the discharge chamber for generating a laser beam, and a processor. The processor runs an energy control algorithm and sends a signal to the discharge circuit based on said algorithm to apply electrical pulses to the electrodes so that the laser beam exiting the laser system has a specified first energy distribution over a group of pulses. The energy control algorithm is based upon a second energy distribution previously determined of a substantially same pattern of pulses as the group of pulses having the first energy distribution. The second energy distribution is determined for the laser beam at a location after passing the beam through beam shaping optical elements of the semiconductor processing system while a value of the energy of the laser beam exiting the laser system is maintained at an approximately constant first energy.