Resonant Soft X-ray Reflectivity for the Chemical Analysis in Thickness Direction of EUV Resist

Abstract

In the advanced lithography, the pattern collapse is significant issue. Since the resist pattern collapse origin to the surface force of the rinse solvent such as ultra-pure deionized water, pattern strip and pattern collapse occur easily when the resist aspect ratio exceeds two. The pattern strip and pattern collapse occur near or at the bottom layer and of a resist inside the resist film, respectively. Thus, the layer analysis inside the resist is significant. The layer separation analysis inside the resist film is very difficult by the X-ray reflectivity method because the layer separation contrast is very small using hard X-ray. Therefore, the resonant soft X-ray reflectivity (RSoXR) method was utilized for the layer separation of the resist film. A commercial chemical-amplifier resist was employed as a sample to in this study. Around carbon absorption edge region of 284 eV, optical index will depend on chemical-bonding structure of the resist strongly. The separated-layer structure was clearly analyzed at 287.1 eV. The resist had 5 nm and 6 nm separated layer at the top and the bottom position.