Proton and anion distribution and line edge roughness of chemically amplified electron beam resist

Nanoscale resist topography such as line edge roughness (LER) or line width roughness (LWR) is the most serious concern in sub-100 nm fabrication. Many factors have been reported to affect LER. However, the cause of LER is still unclear. We calculated proton and anion distribution of chemically amplified electron beam resists in order to make clear the cause of LER. Counter anion distribution is significantly different from proton distribution. Counter anions are inhomogeneously distributed outside a relatively smooth edge of proton distribution. This is caused by the fact that acid generators can react with low-energy (∼0eV) electrons. The inhomodeneous distribution of counter anions outside proton distribution is considered to contribute to LER formation in chemically amplified resists for post optical lithographies.