Resist Performance in 5 nm Soft X-Ray Projection Lithography

Abstract

Imaging experiments in 5 nm soft X-ray projection lithography (SXPL) were performed using 32:1 reduction Schwarzschild optics with NiCr/C multilayer, which was illuminated with synchrotron radiation (SR) from the SORTEC ring. Sensitivities of 0.7 µ m-thick polymethylmethacrylate (PMMA), ZEP and AZ-PN100 are 285, 34, and 15 mJ/cm2, respectively. Resist contrasts (γ-values) of 0.7 µ m-thick PMMA, ZEP and AZ-PN100 are 2.5, 1.6 and 3.1, respectively. A 0.15 µ m line-and-space pattern can be replicated by 5 nm exposure. Resist performance in 5 nm SXPL was investigated with a special emphasis on the effect of resist film thickness. Resist contrasts of PMMA did not change markedly with increasing resist thickness. By 5 nm exposure, a 0.3 µ m line-and-space pattern was clearly delineated in 0.9 µ m-thick PMMA. This result confirms that a single resist scheme is applicable in 5 nm SXPL.