9 - Applications of Ion Microbeams Lithography and Direct Processing

Abstract

This chapter discusses application of focused ion beam lithography, masked ion beam lithography, and ion projection lithography. Focused ion beam lithography is the only means for generating an original pattern at submicrometer dimensions. Focused ion beam lithography is used to write some impressive patterns, such as 15 nm wide features in 60 nm thick PMMA written by 50 keV Ga ions,50 nm features written in 300 nm thick PMMA, and 100 nm wide features in 600 nm thick SAL 601 resist. Comparable features can also be written by e-beam lithography. The other ion lithography techniques, i.e., masked ion beam lithography and ion projection lithography can only replicate an existing pattern. In masked ion lithography protons are used in the 100 keV range. The dose required to expose most organic resists is in the range of 5 × 1011 to 3 × 1013 ions/cm2. Ion projection lithography is a cross between focused ion beam lithography and masked ion beam lithography. Like the focused ion beam it uses ion optics in an ion column, and like masked ion lithography it uses a reticle, i.e., an open stencil mask, to define the pattern.