On-line quality control of the key optical components in lithography lasers using laser induced fluorescence

US6839375B1 · kind B1 · utility

Assignee

• Lambda Physik AG · DE

Inventors

• Peter Lokai · Oettingen, DE
• Farid Seddighi · Oettingen, DE

Key dates

• Filing date: Sep 4, 2002
• Grant date: Jan 4, 2005
• Expiry date: Dec 11, 2022

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N21/6402
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Some of the key optical components of lithography lasers are very sensitive to intensive UV radiation. Intensive UV radiation can cause color center formation in these components. The color centers are reason for laser energy dropping, worse laser-bandwidth and limited life-time. The on-line monitoring of the color-center formation during operation of the lithography lasers detecting laser induced fluorescence and investigation of the fluorescence spectrum can be helpful for maintenance of lithography lasers. The fluorescence signal is analyzed and delivers information about optics quality.