Tone reversal patterning for advanced technology nodes

Abstract

As technology nodes continue to scale down, maintaining roughness and defectivity during the pattern transfer becomes more challenging. For the smallest features, Metal-Organic Resists (MOR) are preferred due to their better selectivity than Chemically Amplified Resists (CAR). However, MORs are usually negative tone resists. Primarily based on defectivity reasons, dark field Extreme Ultraviolet (EUV) masks are strongly preferred over light field EUV masks. Therefore, the MOR resist is more suited for pillar patterning than hole patterning. The purpose of this paper is to show that exposing pillars with MOR and converting them into holes can yield better roughness and defectivity than patterning holes with CAR directly. A similar comparison is done for the tone reversal of lines and spaces. It is shown that the Local Critical Dimension Uniformity (LCDU) of holes and the Line Edge Roughness (LER) of lines/spaces are well conserved throughout the tone inversion process.