Organotin in Nonchemically Amplified Polymeric Hybrid Resist Imparts Better Resolution with Sensitivity for Next-Generation Lithography

Abstract

Given the need for a next-generation technology node in the area of integrated circuits (ICs), improvement in the properties of resist materials, particularly sensitivity (ED), resolution, good etch resistance, and low line edge/width roughness (LER/LWR), has been highly desirable but also extremely challenging. Herein, we report a series of organic–inorganic hybrid nonchemically amplified copolymer resists (n-CARs) bearing radiation-sensitive sulfonium functionality as well as tin metal as an organometallic unit in the structural backbone for low ED and LER/LWR. These resists have been synthesized by the free radical copolymerization of the organic monomer (4-(methacryloyloxy)phenyl)-dimethylsulfoniumtriflate (MAPDST) and acetyldibutylstannyl methacrylate (ADSM) in different feed ratios (97:3, 93:7, 88:12) and characterized using FT-IR, 1H, 19F NMR, GPC, XPS, and ICP-OES techniques. These MAPDST-co-ADSM copolymers exhibited molecular weights (Mw) in the range of 10 077–12 187 g mol–1. Electron beam lithography (EBL) studies revealed that the negative tone n-CARs characteristic with patterning down to sub-15 nm features. The well-developed sub-15 nm nanofeatures showed low LER of ∼1.29 ± 0.07 line patterns (number belongs to feed ratio 93:7). The variable e-beam exposure dose study revealed that the ED of these resists varies with the percentage of incorporated Sn in the polymer matrix. Incorporation of 2.48 wt % Sn (feed ratio 88:12) in the polymer chain led to a significant enhancement in the ED(175 μC/cm2). Furthermore, the mechanistic study of pattern development has been performed with electron beam reactivity analyses using the XPS technique. These investigations substantiate the potential candidature of developed resist formulation for next-generation semiconductor technology applications.

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