Coherent light generators – Particular beam control device – Optical output stabilization
Reexamination Certificate
2000-01-12
2001-11-27
Scott, Jr., Leon (Department: 2881)
Coherent light generators
Particular beam control device
Optical output stabilization
C372S025000, C372S029020
Reexamination Certificate
active
06324196
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved diagnostic system for use with an industrial excimer laser. The diagnostic system allows a service engineer to automatically check the function of the different modules in the trigger chain of a pulsed laser and more easily determine which module is not operating properly. The subject system operates by monitoring pulses generated by each module in the trigger chain.
BACKGROUND OF THE INVENTION
Excimer lasers, that are currently widely used in the semiconductor industry for lithography applications, arc pulsed, transversal, excited gas discharge lasers. The major interest of this industry is the reliability, uptime, and mean time to repair (MTTR) the laser system. If a failure occurs, it must be repaired quickly. Accordingly, diagnosis of a failure in the laser system has to be performed in a short time and the defective part of the system has to be identified and repaired or replaced immediately.
For a pulsed laser, the generation of the light energy, from an externally applied trigger pulse to the ultimate light pulse is critical. Particularly in lithography, it is very important that one light pulse is generated for each trigger pulse. In operation, sometimes more or less output pulses will be generated for each trigger pulse. In the past, when a failure occurred, a service person was required to manually analyze each part of the trigger chain. This analysis was strongly dependent on the experience and knowledge of the service engineer. Usually the engineer checked the input and output of each module to trace where the fault occurred. This process is quite time consuming and difficult. Therefore, it is desirable to have an automated system that can check for faults in the trigger chain of a pulsed laser and report where the fault is located in order to reduce the down time of the laser.
SUMMARY OF THE INVENTION
The object of the present diagnostic system is to help detect in which module a fault has occurred in the trigger chain of a pulsed laser system. This result is achieved by associating each module in the chain with a digital counter, which counts the pulses produced by that module. If the system is operating normally, the counts in each of the counters should be the same. Any deviation in the total counts recorded by each counter is evidence of a problem. If a problem exists, the service engineer will identify the earliest counter in the train where the deviation occurred. This counter will likely correspond to the module where the problem is located. This approach allows the engineer to more easily identify the faulty module without manually checking each module individually.
In the preferred embodiment, a controller computes the difference between the values in each counter and a master counter and then stores the results. If all the modules are operating properly, the difference values will all be zero. Any non-zero value is indicative of a problem.
Jr. Leon Scott
Lambda Physik AG
Sierra Patent Group Ltd.
Smith Andrew V.
LandOfFree
Diagnosis of the trigger chain of a pulsed laser does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Diagnosis of the trigger chain of a pulsed laser, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Diagnosis of the trigger chain of a pulsed laser will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2608468