  The nanoparticle charging processes along with background spatial-temporal
plasma profile have been investigated with 3DPIC simulation in a pulsed EUV
exposure environment. It is found that the particle charge polarity (positive
or negative) strongly depends on its size, location and background transient
plasma conditions. The particle (100 nm diameter) charge reaches steady state
in a single pulse (20 us) within the EUV beam in contrast to particles outside
the beam that requires multiple pulses. The larger the particle size, the less
number of pulses are required to reach steady state. It is found that the
charge of a particle decreases with pressure in a faster rate outside the beam
compared to inside. The results are of importance for particle contamination
(defectivity) control strategy for EUV lithography machines.
