Lithographic apparatus, device manufacturing method, performance measuring method, calibration method and computer program

摘要

A controller for a pulsed radiation source is a closed-loop controller of minimum order, preferably first, to effect dead beat control. Performance indicators for a pulsed radiation source in a lithographic apparatus are based on moving averages (MA) and moving standard deviations (MSD) of the error between target and actual pulse energies. The normalized indicators are given by: ${\mathrm{MA}}_{E,n}\left(x_k\right)=\frac{1}{\sum _{i=k-\left(N_{\mathrm{slit}-e}-1\right)}^k{\mathrm{Ep}}_{\mathrm{ref}}\left(i\right)}.\sum _{i=k-\left(N_{\mathrm{slit}-e}-1\right)}^k{\mathrm{Ep}}_{\mathrm{err}}\left(i\right)\left(k=N_{\mathrm{slit}-e}\mathrm{...}{N}_{\mathrm{scan}}\right),$ wherein Ep_ref(i) and Ep_err(i) indicate reference energy per pulse and energy error per pulse for point i and ${\mathrm{MSD}}_{E,n}\left(x_k\right)=\sqrt{\frac{1}{N_{\mathrm{slit}-e}-1}\sum _{i=k-\left(N_{\mathrm{slit}-e}-1\right)}^k{\left[\frac{{\mathrm{Ep}}_{\mathrm{err}}\left(i\right)}{{\mathrm{Ep}}_{\mathrm{ref}}\left(i\right)}-{\mathrm{MA}}_{E,n}\left(x_k\right)\right]}^2}\left(k=N_{\mathrm{slit}-e}\mathrm{...}{N}_{\mathrm{scan}}\right).$