Resistless EUV lithography: Photon-induced oxide patterning on silicon

Abstract

In this work, we show the feasibility of extreme ultraviolet (EUV) patterning on an HF-treated silicon (100) surface in the absence of a photoresist. EUV lithography is the leading lithography technique in semiconductor manufacturing due to its high resolution and throughput, but future progress in resolution can be hampered because of the inherent limitations of the resists. We show that EUV photons can induce surface reactions on a partially hydrogen-terminated silicon surface and assist the growth of an oxide layer, which serves as an etch mask. This mechanism is different from the hydrogen desorption in scanning tunneling microscopy–based lithography. We achieve silicon dioxide/silicon gratings with 75-nanometer half-pitch and 31-nanometer height, demonstrating the efficacy of the method and the feasibility of patterning with EUV lithography without the use of a photoresist. Further development of the resistless EUV lithography method can be a viable approach to nanometer-scale lithography by overcoming the inherent resolution and roughness limitations of photoresist materials.

Si-Containing Reverse-Gradient Block Copolymer for Inorganic Pattern Amplification in EUV Lithography

“…This innovation facilitates the production of high-resolution patterns beyond the capabilities of other scalable and reliable patterning technologies, positioning EUVL at the forefront of next-generation semiconductor manufacturing. − However, the practical realization of high-NA (numerical aperture) EUVL currently faces a number of technical challenges. One of the most critical challenges is the requirement for a thin photoresist (PR) layer, which leads to low aspect ratios (AR) in the PR etch-mask and, consequently, poor etching performance due to the insufficient endurance of the resist. − Recent studies have focused on mitigating the limitations in pattern resolution and AR encountered in EUVL. These efforts include the development of inorganic-based PRs and the integration of robust hard-mask underlayers to enhance pattern fidelity. − Despite these advancements, the patterns realized under EUV exposure have achieved an AR of only about 2.1, which is suboptimal for reliable pattern transfer during subsequent etching processes …”