Molecular Layer Deposition of a Hafnium-Based Hybrid Thin Film as an Electron Beam Resist

Abstract

The development of new resist materials is vital to fabrication techniques for next-generation microelectronics. Inorganic resists are promising candidates because they have higher etch resistance, are more impervious to pattern collapse, and are more absorbing of extreme ultraviolet (EUV) radiation than organic resists. However, there is limited understanding about how they behave under irradiation. In this work, a Hf-based hybrid thin film resist, known as “hafnicone”, is deposited from the vapor-phase via molecular layer deposition (MLD), and its electron-beam and deep-ultraviolet (DUV)-induced patterning mechanism is explored. The hafnicone thin films are deposited at 100 °C by using the Hf precursor tetrakis­(dimethyl­amido)­hafnium­(IV) and the organic precursor ethylene glycol. E-beam lithography, scanning electron microscopy, and profilometry are used to investigate the resist performance of hafnicone. With 3 M HCl as the developer, hafnicone behaves as a negative tone resist which exhibits a sensitivity of 400 μC/cm2 and the ability to resolve 50 nm line widths. The resist is characterized via X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) to investigate the patterning mechanism, which is described in the context of classical nucleation theory. This study of hafnicone hybrid MLD demonstrates the ability for the bottom-up vapor deposition of inorganic resists to be utilized in advanced e-beam and DUV lithographic techniques.

A Single-Component Molecular Glass Resist Based on Tetraphenylsilane Derivatives for Electron Beam Lithography

“…One approach to solving the limitation of resolution is the development of nonchemically amplified resists (n-CARs). Some novel n-CARs based on polycarbonates, metal-containing clusters, − metal–organic complexes, − polymer containing sulfonium salt, , have been investigated to achieve sub-20 nm patterning under e-beam exposure. Although the resolution has been greatly increased, the sensitivity still needs to be further improved.…”

Induced Chemical Networking of Organometallic Tin in a Cyclic Framework for Sub-10 nm Patterning and Interconnect Application

“…Herein, we demonstrate the potential of an organotin-based cage-like network (Sn–CT) as an inorganic resist system for sub-10 nm patterning (Figure ). In general, at the developmental phase, the resists for EUVL are often screened initially with electron beam lithography (EBL) and helium ion beam lithography (HIBL) to evaluate the patterning potential. − ,− …”

Molecular layer deposition of an Al-based hybrid resist for electron-beam and EUV lithography

“…[10][11][12][13][14][15] Such materials are compositionally similar to hybrid thin films synthesized using molecular layer deposition (MLD), which are coordination polymers in which metal ions are linked by organic ligands. 16 While MLD and spin coating can both deposit hybrid photoresists, the former has several advantages over the latter. MLD can readily grow nanometer-scale photoresists with molecular-level thickness control, thus satisfying the need for thinner resists brought on by the decreased depth of focus in high numerical aperture (NA) EUV lithography.…”

“…MLD can readily grow nanometer-scale photoresists with molecular-level thickness control, thus satisfying the need for thinner resists brought on by the decreased depth of focus in high numerical aperture (NA) EUV lithography. 16 This layer-by-layer technique also provides tunability over the film's chemical composition-and, by extension, its resist properties-by making it possible to synthesize films containing several distinct metal ions or ligands. 16 Despite these advantages, few MLD coordination polymers have been tested as EUV resists, so there is a limited understanding of how the MLD film structure affects its EUV response.…”