Photolithography reaches 6 nm half-pitch using EUV light

Abstract

EUV interference lithography records the interference pattern of two diffracted, coherent light beams, where the pattern resolution is half the diffraction grating resolution. The fabrication of diffraction grating masks by ebeam lithography is restricted by the electron proximity effect and pattern transfer limitations into diffraction efficient materials. By patterning HSQ lines at a relaxed pitch to avoid the electron proximity effect, depositing conformal iridium via atomic layer deposition, followed by ion milling the top and bottom iridium and HSQ removal, we fabricated iridium diffraction gratings at double the line spacing of the original HSQ lines. 6 nm half-pitch patterns were achieved using these masks marking a new record resolution in photolithography.

Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

“…5 Compared with traditional organic chemically amplified photoresists (CARs), some of these inorganic photoresists show higher sensitivity, 2,4,9,10 can form thinner layers, have higher etching resistance, 9 and potentially yield both lower line-edge roughness and higher resolution due to the smaller building blocks. [11][12][13] Such findings have shown the great potential for inorganic materials to be used as EUV photoresist. CARs have now been used and optimized for many years, first for deep UV (DUV) and more recently for EUV, and their critical photochemical reactions are generally well understood.…”

Photochemical conversion of tin-oxo cage compounds studied using hard x-ray photoelectron spectroscopy

“…5 Compared with traditional organic chemically amplified photoresists (CARs), some of these inorganic photoresists show higher sensitivity, 2,4,9,10 can form thinner layers, have higher etching resistance, 9 and potentially yield both lower line-edge roughness and higher resolution due to the smaller building blocks. [11][12][13] Such findings have shown the great potential for inorganic materials to be used as EUV photoresist. CARs have now been used and optimized for many years, first for deep UV (DUV) and more recently for EUV, and their critical photochemical reactions are generally well understood.…”

Progress in EUV resists towards high-NA EUV lithography

“…One good advantage of EUV-IL is that we use the coherent light from synchrotron with the wavelength λ = 13.5 nm, so the theoretical resolution limit of this technique is 3.5 nm [12], that is much higher than the EUV scanner with 0.33NA and the future high NA (0.55NA) [3]. The XIL-IL has successfully achieved world record of 6 nm HP [13] and demonstrated single digital resolution down to 2.5 nm technological node [12]. With the XIL-IL we can investigate the LER and sensitivity of the EUV resist platforms.…”