Hal Amick
The
design of vibration-sensitive advanced technology facilities generally involves
considerable attention to structural and mechanical aspects. In most cases,
the vibration control measures contribute significantly to a facility1s cost.
The selection of a vibration criterion for use in design is an important step
in the design process. Many process equipment manufacturers have provided
tool-specific criteria, and the literature contains several forms of "generic"
criteria. Unfortunately, there is no standardization in either tool-specific
or generic criteria, and considerable confusion can arise. Often the confusion
is associated with the forms of data representation being used.
This paper first reviews some of the relevant fundamentals of signal processing,
then uses experimental data to develop a tool-specific vibration criterion
for an optical microscope. Two dissimilar approaches to generic criteria are
discussed and their signal processing requirements are examined. They are
compared with a manufacturer1s published vibration criteria for a projection
aligner. Recommendations are given for future development of tool-specific
criteria.
Key words: structural dynamics, vibration, vibration analysis, floor motion criteria, microscope criteria, total dynamic system, displacement response, velocity response
Reprinted from
Journal of the Institute of Environmental Sciences
September/October 1997, v. XL, no. 5, pp. 35-44