The impact of aberrations in extreme ultraviolet lithography systems on exposure results

Extreme ultraviolet (EUV) lithography is one of the essential technologies for the 5nm and below technology nodes. However, the presence of aberrations in the system severely affects the exposure results, which can lead to wafer rework and increase costs. In order to investigate the impact of aberrations in EUV lithography systems on exposure results, this paper conducts research on the impact of aberrations on exposure results of patterns that commonly used in EUV single-exposure for the 5nm technology node. A large number of aberration experiments are performed, and the distribution of critical dimension (CD), normalized image log-slope (NILS), Pattern Shift (PS), and process variation band (PVB) of exposure results in relation to all Zernike terms variation within ±50mλ is statistically analyzed. We find that aberrations lead to worse exposure results generally, and the distribution of results does not strictly follow a Gaussian distribution but exhibits significant "tail" phenomena. And the impact of aberrations varies for different patterns. Furthermore, the relationship between the distribution of exposure results and the magnitude of aberrations are investigated. It is observed that as the aberration RMS increases, the probability of deteriorated exposure results also increases. Spherical aberration has a significant impact on CD and PVB, while x-direction coma has a significant impact on the PS of vertical line-space patterns, and y-direction coma has a significant impact on the PS of vertical tip to tip patterns. X-direction astigmatism has a higher probability of causing positive PS, while y-direction astigmatism has a higher probability of causing negative PS. Relatively speaking, the effects of 3-foil, 4-foil, and 5-foil aberrations are smaller. This paper provides a clear reference for the influence of various aberrations on exposure results and can contribute to the future development and aberration control of lithography systems.