Effective Optimization Strategy for Electron Beam Lithography of Molecular Glass Negative Photoresist

Abstract

As the crucial dimension (CD) of logic circuits continues to shrink, the photoresist metrics, including resolution, line edge roughness, and sensitivity, are faced with significant challenges. Photoresists are indispensable in the integrated circuit manufacturing industry, and specifically in achieving smaller critical dimensions. In this study, the effects of two categories of photosensitive compounds on lithography performance are explored, through a series of sulfonium salt-based photoacid generators (PAGs) with diverse reactivity and photodegradable nucleophiles (PDNs) with varying nucleophilicity. The detailed characterization and exposure experiments suggest that the reactive alterations of different PAGs are mostly associated with the amount of phenyl composed of cations in PAGs. The "PDN first, PAG second" strategy, which employs a combination of low reactivity PAG and high reactivity PDN and involves PDN decomposition first and PAG decomposition second in the electron beam lithography process, achieves high sensitivity (100-270 μC cm −2 ), high resolution (25 nm 1:1 line/space, L/S), and low line edge roughness (LER ≤ 3.3 nm) stripes. This approach outperforms conventional formulations and may provide a potentially effective and useful strategy to improve electron beam photoresists.

Progress in Polyhedral Oligomeric Silsesquioxane (POSS) Photoresists: A Comprehensive Review across Lithographic Systems

“…As depicted in Figure 1 , the characteristic size has been reduced from 436 nm (G-line) to 365 nm (UV), to 248 nm (deep ultraviolet (DUV) KrF, 193 nm (ArF excimer lasers), and to even smaller sizes of 13.5 nm and 3–5 nm (extreme ultraviolet (EUV) [ 1 ]. The photoresist, a pivotal material affecting the characteristic size of chips, is subject to increasingly stringent demands regarding its sensitivity, resolution, and line edge roughness, among other properties [ 2 , 3 ]. Typically, a photoresist comprises a film-forming polymer, a photosensitive component, and a solvent.…”

Exceptional Lithography Sensitivity Boosted by Hexafluoroisopropanols in Photoresists

“…Researchers have recently developed a variety of candidate photoresist materials, including chemically amplified photoresists (CARs) [ 10 , 11 , 12 ], metal-based materials [ 13 , 14 ], and cleavage polymer-based non-CARs [ 15 , 16 , 17 ]. Of these, polymer-based CARs are considered the latest qualifying EUV photoresist for realizing high-volume manufacturing [ 18 ].…”

“…Trials to enhance photosensitivity have been conducted using a main chain break [ 30 ] or side-group-bonding PAGs [ 31 ], the addition of a crosslinker [ 32 ] or photosensitizing groups [ 33 ], and other approaches. Small molecules (star-type materials or molecular glass) and metal photoresists are also studied, aiming for high sensitivity and high resolution [ 14 , 15 ]. Ober’s group and Giannelis’ group [ 34 ] reported the first HfO 2 -based metal nanoparticle photoresists and studied them for use in electron beam lithography to obtain 50 nm lines with sensitivity of about 103 µC cm −2 .…”