
485Lithography in the Deep Ultraviolet and Extreme Ultraviolet
Chapter 17
a parameter dened by the pulse count times the uence squared and divided by the
pulse length τ, being proportional to the number of two-photon occurrences within the
sample. Obviously, all the data points lie close to a single straight line, justifying a power
law dependence of the kind
Δ
⎛
⎝
⎜
⎞
⎠
⎟
=
⋅
⎛
⎝
⎜
⎞
⎠
⎟
ρ
u
c
k
NH
2
.
(17.3)
For the exponent c, a value between 0.65 and 0.7 is determined, indicating a sublinear
pulse count dependence, which was described by relaxation of bridging bonds upon
two-photon absorption (Piao et al. 2000). e value of c ~ 2/3 is in agreement with com ...