A 3D energy deposition model guided by resist activation energy for helium ion beam lithography at its resolution limits

We have conducted a detailed investigation of helium ion beam lithography (HIBL) at its resolution limits by calculating three-dimensional energy deposition within a resist. The resist activation energy, a critical physical parameter, was estimated and used as a substitute for the traditional<i>z</i>-factor, allowing for a systematic evaluation of interdependent lithography performances. Our calculations demonstrate HIBL's exceptional capabilities, including 2.5 nm resolution (30 kV, PMMA, line-scan), large aspect ratios exceeding 9, a proximity effect range of approximately 10 nm at 100 nm depth, and edge roughness below 1 nm. These findings highlight HIBL's potential for advanced nanofabrication applications. Furthermore, our calculation led to a reliable model for accurate pattern prediction and proximity effect corrections, which was verified by experiment.