Prediction of resist sensitivity for extreme ultraviolet lithography at 6.x nm wavelength

Oyama, Tomoko*; Oshima, Akihiro*; Washio, Masakazu*; Tagawa, Seiichi*

Potential application of exposure wavelengths shorter than 13.5 nm has recently been discussed for extension of extreme ultraviolet lithography (EUVL), particularly in the 6.x nm range (6.6-6.8 nm). We experimentally investigated the sensitivities of several resists in the EUV/soft X-ray region, including 6.7 nm. Although the sensitivities were strongly influenced by the absorption properties, each resist has a particular required absorption dose regardless of exposure wavelength. Based on these results, we predicted the resist sensitivities and they agreed well with experimentally obtained ones. The prediction method can aid selection and development of resists for 6.x nm EUVL.