Exposure optimization in high-resolution e-beam lithography

In this paper a new method will be described, illustrating how to determine the optimized control point spread function (PSF) for proximity effect corrections (PEC) in e-beam lithography (EBL). A software tool called “PROX-In” was developed in order to help lithographers to determine the numerical inputs for an arbitrary PEC system to satisfy the high critical dimension (CD) control requirements as well as to compensate the shape bias in EBL in connection with the technology steps performed. PROX-In applies new methods allowing highly customized optimum numerical proximity parameter determinations by using a set of extracted experimental data. Compared with other presented methods, this approach is fast and effective. It does not require any additional technology steps and uses only standard measuring techniques. The reviewed method was successfully implemented into mask production for achieving the 90 nm technology node and below at different absorber stacks. It is also used for high-resolution e-beam direct write and SFIL template manufacturing with sub-50 nm resolution.