| Abstract: | A computer-implemented method for determining an optimized purge gas flow
in a semi-conductor inspection metrology or lithography apparatus,
comprising receiving a permissible contaminant mole fraction, a
contaminant outgassing flow rate associated with a contaminant, a
contaminant mass diffusivity, an outgassing surface length, a pressure, a
temperature, a channel height, and a molecular weight of a purge gas,
calculating a flow factor based on the permissible contaminant mole
fraction, the contaminant outgassing flow rate, the channel height, and
the outgassing surface length, comparing the flow factor to a predefined
maximum flow factor value, calculating a minimum purge gas velocity and a
purge gas mass flow rate from the flow factor, the contaminant mass
diffusivity, the pressure, the temperature, and the molecular weight of
the purge gas, and introducing the purge gas into the semi-conductor
inspection metrology or lithography apparatus with the minimum purge gas
velocity and the purge gas flow rate. |