Characterization Studies on Metal-based EUV Resist Film Properties

Abstract

Investigations on the resist film depth-profile of a Zr-based EUV metal resist (which contains methacrylic acid or MAA as shell) reveal that the metal cores (Zr) are homogeneously distributed across the film-depth. However, the shell molecules (MAA) in the same resist film have an inhomogeneous distribution (relatively high concentration at the film surface compared to the film bottom). In addition, the total concentration of shell molecules across the film depth is significantly affected (decreases) due to post coating delay and increased exposure dose. Moreover, it is confirmed that the existence of such metal resist film depth inhomogeneities affects the resist's dissolution properties in the developer solution. Specifically, variations in metal resist dissolution characteristics between the film surface, mid-film, and the film bottom are observed. These results confirm the impact of metal resist film properties on its solubility in the developer solution, which can directly affect patterning performance (resolution, line edge/width roughness (LER/LWR), and sensitivity), especially LER/LWR. Keywords: EUV metal resist, Film depth, Inhomogeneity, In situ resist dissolution analysis Experimental conditions 2.1. Materials and processingA metal resist (developed in-house) with a zirconium (Zr) core and a methacrylic acid (MAA) shell was used in these experiments [10,12,24,32,33]. The film thickness was ~30 nm under a postapplication bake (PAB) condition of 80 °C for 60 s. The dissolution process was conducted using normal butyl acetate (nBA) as the developer. This metal resist works as a negative tone type material

Chemical Mechanisms of Metal-Based Extreme Ultraviolet Resists

“…A wide variety of hybrid organic-inorganic metal oxoclusters has been reported in the recent literature [11]. To date only a few of those have been explored for EUV lithography, in particular containing Ti [12], Zr [13,14], Hf [12,15], and Zn [16,17]. Two examples are shown in Figure 1.…”

Dissolution dynamics of zirconia nanocluster resist

“…The oxygen bridges between tin-oxo cages are generated through dehydration. [4][5][6][7][8] For the zirconia nanocluster resists with methacrylate (methacrylic acid anion) (MAA) ligands, more details have been investigated using hard X-ray photoelectron spectroscopy, 9) near edge X-ray absorption fine structure spectroscopy, 9) X-ray diffraction, 9) time-of-flight secondary ion mass spectrometry with gas cluster ion beam, 10) a mid-IR free electron laser, 11) scanning transmission electron microscopy, 12) simulation, 13,14) electron pulse radiolysis, [15][16][17] and γ-radiolysis with gas chromatography 18) and high performance liquid chromatography. 19) Upon exposure to ionizing radiations, the radical cations of MAA are generated through the direct oxidation by ionizing radiations (ionization) and the oxidation by the oxidizing agents also generated by ionizing radiation (hole transfer).…”

Functionalized Ag Nanoparticles Embedded in Polymer Resists for High-Resolution Lithography

“…In this progress, Nandi et al has produced high-aspect-ratio patterns of 100 nm with an ionic photoacid generator-included Terpolymer photoresist, viz., GBLMA–MAMA–MAPDST . Apart from CARs, hybrid resists are also being considered as emerging candidates for current lithography technology mainly due to their patterning potential for high-resolution features in the absence of PAGs in resist compositions. − Similarly, metal–organic clusters and methacrylate-based materials without any PAG have also been reported with notable sensitivity toward all types of irradiations. − Recently, our group developed nickel-based negative tone resists using EBL/HIBL and showed sub-10 nm line patterning. , Also, the negative tone chromium-containing resists revealed the patterning capability and high-etch resistance to silicon and tungsten at sub-10 nm resolution …”