Chamber Pumpdown Studies

Benefits

Residual gas analyzers are valuable tools for vacuum system maintenance and pumpdown studies. Many users limit their RGA uses to just leak detection after a problem has been discovered because the chamber does not meet base pressure specifications. The following studies show the value of vacuum chamber monitoring during the initial pumpdown after PM's.

The object of the studies was to find problems early in the pumpdown routine and correct them to decrease the total cycle time. Once certain problems were identified, the technicians could then be alerted with the new Process Eye alarm and warning screens. Since these alarms would be built in to the recipe, the technicians would not be required to have RGA analysis knowledge.

The first chamber in this series shows a normal pumpdown to an acceptable base pressure for the process to begin. The rest of the chambers all had some problem that caused longer pumpdown cycles or unacceptable final RGA scans. These chambers had to go through another cycle to reach acceptable levels.

Early warning of the chamber problems, and correction of them, could have saved the more than 150 hours of time in just these six systems. This was the time required to rerun the tests. This related to a loss of 150 hours of production time!

MKS Instruments continues to work with their customers to develop new software and RGA hardware to be able to solve this type of problem in production and other vacuum process applications.

Experiment

Develop a testing method for the bakeout and testing of vacuum chambers used in production. The object was to watch and monitor the chambers to learn about the pumpdown cycle. The second objective was to pinpoint items that could be changed to decrease the pumping time and improve the base vacuum levels. Data was collected throughout the pumpdown, bakeout and cooldown of the chambers.

Equipment

The initial testing was done with a new Vision 1000 B package. This includes a MicroVision control unit and a high sensitivity dual filter, open ion source analyzer. Data was collected with the RGA for Windows software package to determine parameters and conditions for future experiments. Later monitoring and control will be done with the Process Eye software and the built-in alarm and warning screens. Complete scans were taken from 1 to 100 and stored to disk for later RECALL in Bar Graph or Trend displays.

Next Page - Results

This information is subject to change without notice.

Need help?

Contact an Applications Specialist by sending an email to MKS Instruments or call 408-750-0300.