Fluorinated-Polymer Based High Sensitivity Extreme Ultraviolet Resists

Abstract

There is a growing interest in the fluorinization of resist materials in improving pattern formation efficiency for extreme ultraviolet (EUV) lithography. The increased polymer absorption coefficient obtained through this resist platform is expected to enhance acid production and in effect improve pattern formation efficiency. Based on this, a EUV resist which was synthesized by co-polymerizing tetrafluoroethelyne (TFE) and functional norbornene derivative was investigated. Relatively high sensitivity of 6.3 mJ·cm-2 for half-pitch (hp) 45 nm and satisfactory resolution limit of hp 40 nm was achieved. However, at present, line width roughness (LWR) was measured at comparatively large values of more than 8.4 nm at hp 45 nm. Further material and process optimizations may be necessary to improve its present lithographic capability. However, these initial results have shown the potential of fluorinated-polymer based platform as a possible solution for high sensitivity, high resolution and low LWR EUV resists.

The Influence of H2Plasma Treatment on LWR Mitigation: The Importance of EUV Photoresist Composition

“…To compensate the lack of photons in EUV lithography, the efficiency of the deprotection reactions or the acid generation has to be enhanced. The latter can be improved, for example, by the introduction of fluorine atoms in the polymer . The photo‐acid generators are based on similar chemistries as those used in KrF and ArF lithography, but their sensitivity is optimized for photons with wavelength of 13.5 nm.…”

“…The latter can be improved, for example, by the introduction of fluorine atoms in the polymer. [20,21] The photo-acid generators are based on similar chemistries as those used in KrF and ArF lithography, but their sensitivity is optimized for photons with wavelength of 13.5 nm. The quantum efficiency for acid formation in EUV was found to be up to one order of magnitude higher than at 193 nm, mainly due to the excitation mechanism by secondary electrons.…”

A Comprehensive Review of EUV Resist Materials and Processing at Selete

“…At present, EUV resist sensitivity and resolution limits continue to be improved but line width roughness (LWR) still remains a difficult issue [2] . To provide possible solutions, there is a trend in individual and collaborative efforts between research consortiums, universities, and resist material developers on the investigation of new EUV resist platform and material designs [3][4][5][6][7][8][9] . This is also true for the conceptualization and application of alternative resist processes which have shown significant potential as pattern sizes become smaller [10][11][12][13] .…”