Patent Number: 6,490,307

Title: Method and procedure to automatically stabilize excimer laser output parameters

Abstract: A method and apparatus is provided for stabilizing output beam parameters of a gas discharge laser by maintaining a constituent gas of the laser gas mixture at a predetermined partial pressure using a gas supply unit and a processor. The constituent gas of the laser gas mixture is provided at an initial partial pressure and the constituent gas is subject to depletion within the laser discharge chamber. A parameter such as time, pulse count, driving voltage for maintaining a constant laser beam output energy, pulse shape, pulse duration, pulse stability, beam profile, bandwidth of the laser beam, temporal or spatial coherence, discharge width, or a combination thereof, which varies with a known correspondence to the partial pressure of the constituent gas is monitored. Injections of the constituent gas are performed each to increase the partial pressure by a selected amount in the discharge chamber. A number of successive injections is performed at selected intervals to maintain the constituent gas substantially at the initial partial pressure for maintaining stable output beam parameters.

Inventors: de Mos; Bruno Becker (Biebesheim, DE), Stamm; Uwe (Gottingen, DE), Vogler; Klaus (Gottingen, DE)

Assignee: Lambda Physik AG

International Classification: G03F 7/20 (20060101); H01S 3/14 (20060101); H01S 3/134 (20060101); H01S 3/225 (20060101); H01S 3/036 (20060101); H01S 003/22 (); H01S 003/223 ()

Expiration Date: 12/03/2019