This paper describes a metal oxide patternable hardmask designed for EUV lithography. The material has imaged 15-nm half-pitch by projection EUV exposure on the SEMATECH Berkeley MET, and 12-nm half-pitch by electron beam exposure. The platform is highly absorbing (16 µm -1 ) and etch resistant (>100:1 for silicon). These properties enable resist film thickness to be reduced to 20nm, thereby reducing aspect ratio and susceptibility to pattern collapse. New materials and processes show a path to improved photospeed. This paper also presents data for on coating uniformity, metal-impurity content, outgassing, pattern transfer, and resist strip.

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The authors present a directly photopatternable inorganic hardmask for 193 nm lithography based on the solution-deposited dielectric metal oxide sulfate (MSOx) system. To demonstrate pattern fidelity, 18 nm half-pitch features were written at a dose near 240 μC/cm2 (30 keV) with line width roughness values between 1.6 and 1.8 nm. Well-resolved and uniform 30 nm contact holes were fabricated via a litho-freeze-litho-etch process employing electron beam exposure and a simple thermal freeze. ZircSOx has a high index of refraction approaching 1.9 at 193 nm, and the extinction coefficient, k, can be varied by an order of magnitude by substituting Zr with Hf. Optical interference lithography at 193 nm was used to realize 60 nm half-pitch lines in MSOx at a dose of 25 mJ/cm2.

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The dehydration of hafnium oxide hydroxide sulfate thin films was studied using temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy. Films were found to desorb water up to 750 K with a maximum desorption rate at~480 K. Carbon dioxide desorption was also observed in TPD measurements, which was related to contamination of precursor solutions and/or films by CO 2 from the atmosphere. The O 1s spectra obtained for in-situ annealed samples were fit with three components corresponding to Hf-O, hydroxyl groups, and sulfate groups. Water TPD measurements from the dehydrated surface indicate the presence of two desorption states corresponding to molecularly and dissociatively adsorbed water.