Limiting factors in sub-10 nm scanning-electron-beam lithography

Achieving the highest possible resolution using scanning-electron-beam lithography (SEBL) has become an increasingly urgent problem in recent years, as advances in various nanotechnology applications [F. S. Bates and G. H. Fredrickson, Annu. Rev. Phys. Chem. 41, 525 (1990); Black , IBM J. Res. Dev. 51, 605 (2007); Yang , J. Chem. Phys. 116, 5892 (2002)] have driven demand for feature sizes well into the sub-10 nm domain, close to the resolution limit of the current generation of SEBL processes. In this work, the authors have used a combination of calculation, modeling, and experiment to investigate the relative effects of resist contrast, beam scattering, secondary electron generation, system spot size, and metrology limitations on SEBL process resolution. In the process of investigating all of these effects, they have also successfully yielded dense structures with a pitch of 12 nm at voltages as low as 10 keV.