Dual grating interferometric lithography for 22-nm node

An extreme ultraviolet (EUV) interference lithography beamline using a single grating has been constructed at the BL3 beamline in the NewSUBARU synchrotron radiation facility. Using a single grating, a 400-nm line and space (L&S) resist pattern was replicated on a wafer by single grating interferometric lithography system combined with a bending magnet as a light source. In addition, a dual grating interferometric lithography which is suitable for a bending magnet as a light source has been designed and constructed at the BL3 beamline in NewSUBARU. Dual grating interferometric lithography has a capability to replicate of a 28 nm L&S pattern on the basis of the interference-fringes calculation under conditions of a partial coherent light source such as a bending magnet. In the dual grating interference optical system, two transparent gratings was employed. In addition, the dual grating interference lithographic exposure method can be combined with a stand alone EUV source, such as a laser produced plasma or a discharge produced plasma. Therefore, this exposure system is a compact system for the evaluation of resolution and line edge roughness (LER) in a EUV resist.