Fan,


It all depends what your total cleaning system is and what you are
trying to clean. For bare Silicon an ultrasonic with RCA clean multi
sink clean and final wafer scrubber can obtain particle levels of <10@
0.2um / cm2. A megasonic can produce similar levels with a good clean
without use of a surface wafer scrubber. ( both are diameter dependent)
The megasonic is a higher frequency so has improved capability to
energize and remove smaller particles on polished wafers surface and is
better for double side polished wafer- non contact cleaning.

Megasonics are also better for cleaning MEMS products before final
surface layering and they clean 'deeper'

For other than bare polished  - it really depends on what you are trying
to clean--
Megasonic systems are significantly higher priced than ultrasonic systems.
I don't know the exact energy level of Ult vs Meg- but sure someone can
fill in these blanks.

Ken
Pi, Fan wrote:

> Can someone help me understand the difference between ultrasonic and
> megasonic
> clean mechanisms? Why do we generally need to use megasonic clean in Si
> process
> instead of ultrasonic clean?
> Thanks,
>
> Fan Piao
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