Development of ion sources: Towards high brightness for proton beam writing applications

An Ion Source Test Bench (ISTB) has been designed and commissioned to facilitate the measurement of ion beam reduced brightness (Br) obtained from different ion sources. Preliminary Br measurements were carried out, with RF ion source, in the ISTB for He ions. Meanwhile we have also fabricated and tested a novel ion source called electron impact gas ion source, whose reduced brightness is expected to reach up to 107 pA/μm2 mrad2 MeV. Initial ion-current measurements from such electron impact gas ion source (tested inside an environmental SEM) has yielded about 300 pA of Ar ions. The areal ion current density from this electron impact gas ion source is found to be at least 380 times higher than the existing RF ion source. This novel ion source is promising for application in proton beam writing lithography with feature sizes smaller than 10 nm.