High repetition rate gas discharge laser with precise pulse timing control

US6618421B2 · kind B2 · utility

Assignee

• Cymer, LLC · US

Inventors

• Palash P. Das · Vista, US
• Jennan Yu · San Diego, US
• Stuart L. Anderson · San Diego, US
• Helmut Schillinger · Herzogenaurach, DE
• Tobias Pflanz · Munich, DE
• Claus Strowitzki · Gilching, DE
• Claudia Hartmann · Mering, DE
• Stephan Geiger · Wurmlingen, DE
• Brett D. Smith · Chesterfield, US
• William N. Partlo · Poway, US

Key dates

• Filing date: Apr 18, 2001
• Grant date: Sep 9, 2003
• Expiry date: Aug 7, 2021

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01S3/2207
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A high repetition rate, compact, modular gas discharge, ultraviolet laser. The laser is useful as a light source for very rapid inspections of wafers in an integrated circuit fabrication process. It is also useful for reticle writing at very rapid rates. A preferred embodiment operates at pulse repetition rates of 1000 to 4000 Hz and is designed for round-the-clock production line operation. This preferred embodiment comprises a pulse control unit which controls the timing of pulses to an accuracy of less than 4 nanoseconds. Preferred embodiments of this gas discharge laser can be configured to operate with a KrF gas mixture, an ArF gas mixture or an F2 gas mixture, each with an approximate buffer gas, producing 248 nm, 197 nm or 157 nm ultraviolet light pulses.