Metal Containing Resist Readiness for HVM EUV Lithography

Abstract

The use of metals in extreme ultraviolet (EUV) lithography to have the highest productivity with low exposure dose requirements (below 20mJ/cm 2 ) has recently developed an increased interest. The motivation of using metals in the formulation of EUV photoresists stems from the high EUV cross sectional absorption of several metal species that give the opportunity to enhance the EUV absorbance capacity compared to a traditional pure organic resist and thus capture more productive photons, improving the resist sensitivity. The challenge is to keep a high performing switching solubility mechanism, to maintain patterning fidelity and to mitigate shot noise with a better tradeoff between sensitivity and line width roughness (LWR) when compared to a traditional resist. Further, a possible introduction of a metal containing resist (MCR) in a high volume manufacturing (HVM) line opens new scenarios at the contamination and process level about the management of the wafers and tools and MCRs need to demonstrate high capacity to compete with traditional organic photo materials.In this work we have looked at two different aspects of MCRs: the electron response as initial fundamental study on the light-photoresist interaction and the patterning performance in EUVL as manufacturability aspect of such a class of metal photoresists. The obtained results give indication that adding a metal into a CAR formulation may not be sufficient to increase the electron response of such a resist when exposed under the EUV light. Further, an MCR does not necessarily give good EUV lithographic performance, suggesting that the benefit from metals in terms of higher electron response or higher photon absorption can be fully realized only if the chemistry is right. On another hand, when the right chemistry is realized, we demonstrate that the litho-etch integration in a module is feasible for an MCR. In this paper the pattern transfer on stacked wafer for 22nm line-space dense features is successfully demonstrated using an MCR high imaging performance. Furthermore, the cross contamination results on an etch chamber tool are successfully presented. With the demonstrated etch capability, the metal containing resists move a step forward reducing the gap between the R&D and the manufacturing stage.

Key Role of Very Low Energy Electrons in Tin-Based Molecular Resists for Extreme Ultraviolet Nanolithography

“…Among the variety of materials that are being investigated for EUVL applications, metal–organic materials, also called inorganic resists, are considered the most promising. Their main advantage is that the incorporation of metallic elements enhances EUV absorptivity . In particular, Sn-containing materials have attracted much attention as they can yield nanopatterns at relatively low doses. − Yet, a lack of detailed understanding of the chemical processes occurring upon the absorption of EUV photons hinders the rational design of efficient resists.…”

Extreme ultraviolet patterning of tin-oxo cages

“…These have a larger absorption cross section for EUV photons than organic materials, which contributes to an increase in sensitivity. 5 This may eliminate the need for chemical amplification, removing statistical uncertainties in the position of photoacid generators and quenchers. Metalcontaining compounds also have an improved etch resistance compared to conventional chemically amplified resists (CARs).…”

The Challenges of Advanced CMOS Process from 2D to 3D

“…One of the critical technical issues of EUVL is the development of resist material which has high resolution and high sensitivity as well as low line-edge roughness and low outgassing simultaneously [16,17].…”