Fundamentals of Vacuum Flashcards
Wafer process chambers are made of materials that have a ____ vapor pressure.
Low
High
It does not matter
Low
turbulent flow is highly desirabl in a process chamber with production wafers in it to help knock particles off of the wafers to keep them clean.
True or False
False
Many semiconductor processes are done under vacuum mainly to _____.
Reduce the number of unwanted chemical reactions
Increase chemical reactions
Keep the Fab environment clean
Keep wafers clean
Reduce the number of unwanted chemical reactions
At viscous flow, the mean free path of molecules is ____ than that of molecules at molecular flow.
Longer
Shorter
The same
shorter
Gasses in molecular flow are ____ likely to collide with each other than the chamber walls.
More
Less
Equally
Less
On top of Mount Everest, the atmospheric pressure is ____ than at sea level.
The same
Higher
Lower
Lower
The function of a vacuum pump for wafer processing is to ____ the gas density in a given volume.
Increase
Reduce
Equalize
Reduce
The definition of vacuum refers to a given space filled with a gas at pressure ____ atmospheric pressure.
above
at
below
Any of the above
Below
Gasses in viscous flow generally move ____ than gasses in molecular flow.
Slower
Faster
About the same
Faster
Safety considerations in a wafer vacuum system include:
Electrical
Weight
Gas handling
All of the above
Only A and C
All of the above
The fundamental vacuum seal is provided by ____.
Krytox grease
End caps
O-rings
Flanges
O-rings
