Aberration model in extreme ultraviolet lithography for device reliability

As one of the most critical processes in the manufacturing of micro-nano devices, the quality of the lithography results affects the reliability of devices and the realization of circuit functions directly. Moreover, the manufacturing of gate-all-around (GAA) devices must rely on the most advanced extreme ultraviolet lithography (EUVL). However, aberrations in the EUV lithography system have a significant and non-negligible impact on the lithography results. In order to reflect the relationship between the aberrations and the critical dimension (CD) of the lithography results intuitively and further estimate the changes in device performance, this paper proposes an analytical aberration model for device reliability. In an attempt to reduce the incidence of large aberrations in EUVL by introducing a Poisson distribution function with multiple correction factors, the distribution of the CD variation is obtained under the influence of aberrations. Then, the functional relationships between the magnitude of the aberrations and each correction factor are obtained by curve fitting. By integrating the above results, an analytical model depicting the relationship between the magnitude of aberrations and the distribution of the CD variation is ultimately established. Based on this model, the distribution of lithography results under various aberrations can be clearly visualized, and then the changes in device performance and even the functions of the entire circuit can be estimated. For example, when the root mean square (RMS) value of the aberration is restricted from 50mλ to 40mλ, the change in the saturation current of the GAA device will decrease by 30.9%. This model can help designers understand the basic process capabilities and the realization of functions before device manufacturing, and then optimize at the design stage to avoid excessive performance losses caused by the process in the early stage of design.