Types of ion-beam lithographies

There are three ways in which ion beams are employed in lithography (see Fig. 15.8). A point beam can be focused to a fine spot ( 10 nm) from a bright point source and deflected on the surface, in an arrangement called focused ion beam (FIB), to expose the resist directly without a mask. Two types of ion sources, liquid metal and gaseous (cryogenic) field ion source, have been successfully used in this technology. Of these two sources, liquid metal has 

MelngaiUs, AppUcations of ion microbeams in lithography and direct processing, Handbook of VLSI Microlithography, 2nd ed., J.N. Helbert, Ed., William Andrew Inc., pp. 790 855 (2001). Other applications of focused ion beam in integrated circuit industry include device repair, failure analysis, and direct implantation of ions into substrates. 

Stencil mask in close proximity to the wafer Wafer 

The second way to employ ion beams in lithography is to place a stencil mask in close proximity to a surface and irradiate the mask with a collimated beam of ions. This is referred to as proximity ion-beam lithography, and it is a 1 1 

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