Equation correlation
08/01/1997
Equation correlation
n the article "193-nm lithographic systems lifetimes as limited by UV compaction" (April, p. 95), Eqn. 2 fails in the dimensional analysis. As it follows from the article:
Dr
= k(NI2/t)0.7
where
Dr
= UV induced densification (ppm)
k = a constant (ppm)
N = number of pulses (millions)
I = energy density (mJ/cm2)
t = pulse length (ns)
Thus, for the physical dimensions of the above parameters, one can write:
ppm = ppm (million ? mJ2/cm4 ? nsec)0.7
that does not make any physical sense.
Therefore, either the equation or the description should be corrected.
Igor Murokh, PhD
Tri-Star Technologies
El Segundo, CA
The article`s author, Richard Schenker, responds: An identical and clearer construction for Eqn. 2 can be used:
 |
where
t = pulse length
Np = number of pulses
k = a constant
I = 193-nm energy density
to = 1 ns
Io = 1 mJ/cm2