Secondary particle effects in focused ion beam induced depositions

Abstract

Summary form only given. The use of focused ion beams (FIB) in conjunction with precursor gases to induce site specific deposition of metals and dielectrics has greatly increased the utility of FIB systems in semiconductor device modification and failure analysis applications. Our study concentrates on the role of secondary electrons in FIB induced depositions, which has been postulated as an element of the deposition mechanism. Specifically we have examined the relationship between deposition efficiency and secondary electron yield in three ways, (1) by studying the deposition of SiO/sub 2/ on high and low atomic number (Z) substrate material, as well as on substrates with thin layers of high Z material, (2) by examining the deposition through the use of secondary electrons generated by the FIB far from the scanned regions, and (3) by studying the deposition through the use of secondary electrons generated by a primary beam of electrons. The results indicate a weak dependence of the deposition efficiency on the secondary electron coefficient (which scales with atomic number). However, depositions produced by secondary electrons generated far from the scanned regions by the primary ion beam, have shown ∼3× improvement in the deposition rate over depositions produced by the FIB within the scanned region. These results suggest the expanded role the secondary electrons may play in the deposition process, as well as point to a novel methodology which may be used in re-passivating large and small areas on devices.