Evaluation of advanced epoxy novolac resist, EPR, for sub 100nm synchrotron x-ray proximity lithography

The performances of the advanced cresol epoxy novolac-based resist, EPR, were characterized for use of synchrotron x-ray proximity lithography at PALC(Postech Advanced Lithography Center). Although the high sensitivity and resolution capability of the EPR in e-beam lithography had been reported [1], its performances in the x-ray lithography have not been well investigated yet. We compared EPR to TDUR-N908 [2] of TOK, which is commercially available high sensitive negative tone resist used in x-ray lithography. The Experiments showed about 8 times higher sensitivity of EPR than that of TDUR-N908. The fine-line resolution capability of EPR was proven down to double spaced 80 nm dense lines. The contrast of EPR depends more on FEB temperature within the ranges of 90 degrees C similar to 100 degrees C rather than PAB temperature of 130 degrees C similar to 150 degrees C. But the sensitivity was not much changed by those variations of FEB and PAB temperature. In addition, we optimized the resist process of EPR for sub 100 nm regime in this work.