Master oscillator/power amplifier excimer laser system with pulse energy and pointing control

US7158553B2 · kind B2 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Sergei V. Govorkov · Mountain View, US
• Alexander Wiessner · Oettingen, DE
• Rainer Paetzel · Dransfeld, DE
• Igor Bragin · Göttingen, DE

Key dates

• Filing date: Feb 11, 2004
• Grant date: Jan 2, 2007
• Expiry date: Jan 9, 2025

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/2333
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Pulse parameters of a gas discharge laser system can be optimized and controlled for precision applications such as microlithography. Important laser pulse parameters typically vary in the beginning of a pulse burst, and the directionality of the output beam typically varies throughout the burst. In order to improve the performance of the laser system, the variation at the beginning of a pulse burst can be eliminated by extending the pulse pattern and shuttering the output during periods of significant parameter variation. A fast shutter such as an acousto-optical modulator can be used to prevent output during the burst transition processes. Elements such as acousto-optical cells also can be used in combination with a fast position sensor to steer the direction of the output beam, in order to adjust for variations in the direction of the beam between pulses in a burst.