Simulation of Optical Constants Range of High-Transmittance Attenuated Phase-Shifting Masks Used in KrF Laser and ArF Laser

Abstract

Phase-shifting masks (PSMs) have provided us a breakthrough in the future semiconductor industry by extending lithography further to the submicrometer order. PSMs have been used over the past several years, and their requirements have changed due to the development of semiconductor technology. We investigated high-transmittance attenuated PSMs (HT-Att-PSMs) that satisfy the requirements of 20 ± 5% transmittance and 180 • phase shift at the exposure wavelength and less than 40% transmittance at the inspection wavelength. Regarding the wavelength, we targeted the inspection wavelength of 248 nm for ArF laser (exposure wavelength of 193 nm) HT-Att-PSM, and 365 nm for KrF laser (exposure wavelength of 248 nm) HT-Att-PSM. In this study, we developed refractive index-extinction coefficient-thickness (n-k-d) charts showing optimum optical constant ranges for HT-Att-PSM using the matrix method. The simulation was verified by comparing calculated transmittance data with measured ones.

Stochastic Patterning Simulation Using Attenuated Phase-Shift Mask for Extreme Ultraviolet Lithography

“…This structure has a reflectivity of $6% at the absorber stack and exhibits a phase difference of 180 (typically transmittance of 6-18% for a deep-UV PSM). [18][19][20][21][22] The resist patterning properties of the PSM were compared with those of a conventional binary intensity mask (BIM) with a 70-nm-thick TaN absorber layer in the patterning of an 18 nm line and space (L/S) 1 : 1 dense pattern. The exposure conditions of a high-volume manufacturing tool (ASML NXE:3300) were used, which are a numerical aperture (NA) of 0.33, partial coherence () of 0.2-0.9, incident angle of 6 , and demagnification factor of 4.…”

Very Thin Extreme Ultraviolet Mask Absorber Material for Extremely Fine Pitch Patterning

“…5. Since an attenuated PSM requires a small percentage of light to pass through (typically 6 or 18% for a deep-UV PSM), [19][20][21][22][23] 20 nm PdO with a reflectivity of 7.5% and a phase difference of 172 was selected for further investigation. Under these absorber conditions, an image contrast as high as 88% was obtained for 14 nm hp L/S patterns.…”