Etching of optical device material using IBF(V)
–Measurement of ion beam profile using a Faraday cup array

Abstract

Ion beam fabrication (IBF) is suitable for figuring high precision optics elements used for reflective optics of extreme ultraviolet lithography (EUVL). A dwell time control of an ion beam is performed in shape correction of the optics elements. For this purpose, it is necessary to stabilize an ion beam in time and space. At first we investigated time stability of Ar ion beam and also the current density distribution of the beam. Next we examined the current density distribution of the ion beam when the beam was squeezed with aperture. As a result, it is found that the ion beam current was unstable for five hours after ignition of plasma, then it become stable for five hours. Also, the distribution of the current density might change depending on the distance from aperture when the beam was passed through it.