EUV and optical lithographic pattern shift at the 5nm node

Abstract

At the 5 nm technology node there are competing strategies for patterning: high-NA EUV, double patterning 0.33 NA EUV and a combination of optical self-aligned solutions with EUV. This paper investigates the impact of pattern shift based on the selected patterning strategy. A logic standard cell connection between TS and M0 is simulated to determine the impact of lithographic pattern shift on the overlay budget. At 5 nm node dimensions, high-NA EUV is necessary to expose the most critical layers with a single lithography exposure. The impact of high-NA EUV lithography is illustrated by comparing the pattern shift resulting from 0.33 NA vs. 0.5x NA. For the example 5 nm transistor, cost-beneficial lithography layers are patterned with EUV and the other layers are patterned optically. Both EUV and optical lithography simulations are performed to determine the maximum net pattern shift. Here, lithographic pattern shift is quantified in terms of through-focus error as well as pattern-placement error. The overlay error associated with a hybrid optical/selfaligned and EUV cut patterning scheme is compared with the results of an all EUV solution, providing an assessment of two potential patterning solutions and their impact the overall overlay budget.

Emulation of anamorphic imaging on the SHARP extreme ultraviolet mask microscope

“…For vertical features, parallel to the plane of incidence, the illumination is centered, causing less shadowing. 2 EUV projection lenses at higher demagnification ratios, beyond 4x show acceptable imaging performance. But printing one full field at two-times higher demagnification either requires a photomask with four times the surface area, or the field needs to be stitched from four quarterfield exposures.…”

“…1 Feature sizes at these nodes require the use of resolution enhancement techniques in EUVL from the start, not leaving much room to further decrease critical dimensions (CD) without using double patterning. 2 The next generation of EUVL at higher NA is under development now and will be required soon after the insertion of EUVL into production in order to keep the technology on track down to smaller feature sizes. The wafer-side NA of a lithography system may be increased by either increasing the maskside NA, increasing the demagnification of the system, or a combination of the two.…”

Inverse analysis of multilayer defects in EUV mask from the perspective of imaging performance

“…This undeniably signifies a model of high accuracy. The specific mathematical relationship resulting from the fitting is detailed in Expression (2). By setting the CD value fluctuation range to ±10% of the target feature value, utilizing the mathematical model for reverse calculations yields permissible ranges for height and FWHM as 0-1nm and 0-0.95nm, respectively.…”

“…Extreme Ultraviolet (EUV) lithography is a crucial tool for manufacturing integrated circuits in technology node of 5nm and below 1,2 . Considering the strong absorption of EUV light by materials, both EUV masks and optical systems adopt reflective structures to minimize energy loss during the propagation of EUV light.…”