Manufacturing sub-50-nm gratings using E-beam lithography and electroplating

Mark Kroon; Falco C.M.J.M. van Delft; Bas Ketelaars

doi:10.1117/12.472278

1 July 2002 Manufacturing sub-50-nm gratings using E-beam lithography and electroplating

Mark Kroon, Falco C.M.J.M. van Delft, Bas Ketelaars

Proceedings Volume 4688, Emerging Lithographic Technologies VI; (2002) https://doi.org/10.1117/12.472278
Event: SPIE's 27th Annual International Symposium on Microlithography, 2002, Santa Clara, California, United States

Abstract

In this paper we present a new method for manufacturing steeply profiled grating structures composed of narrow lines and spaces embedded in transition metal layers. We focus on making EUV transmittive grating structures typically consisting of rectangular lines that are down to 40 nm wide, around 100 nm tall, up to 100 nm long, spaced at a 1-2 micrometers pitch, and embedded in 100 nm thick nickel-iron alloy absorber layers. The method comprises the use of a molybdenum plating base deposited on a silicon nitride coated silicon wafer, electron beam writing of down to 40 nm wide and 100 nm tall lines in negative tone hydrogen silsesquioxane (HSQ) resist, and electroplating of the desired metal absorber layer in between the resist lines, using the molybdenum layer as plating base. After processing both the HSQ resist and the thin plating base can remain respectively between and below the grating structure because these materials are relatively transparent to EUV radiation. The presence of HSQ in the plated metal spaces results in a flat top surface, preventing the adhesion of contaminants. Our measurements reveal the presence of rectangular HSQ lines, characterized by near vertical side walls, a high line-width uniformity and a low line-edge roughness. These structures are subsequently embedded in a homogeneously grown absorber, characterized by a low small-scale surface roughness and high-quality overall flatness. The process window, in terms of exposure dose and pre-exposure resist treatment, has been well established for various line width and line pitch settings.

Citation Download Citation

Mark Kroon, Falco C.M.J.M. van Delft, and Bas Ketelaars "Manufacturing sub-50-nm gratings using E-beam lithography and electroplating", Proc. SPIE 4688, Emerging Lithographic Technologies VI, (1 July 2002); https://doi.org/10.1117/12.472278

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