Evaluation of Mo/Si multilayer for mask blank H. Yamanashi, T. Ogawa, H. Hoko, B. T. Lee, E. Hoshino, M. Takahashi, N. Hirano, A. Chiba, H. Oizumi, I. Nishiyama, and S. Okazaki Association of Super-Advanced Electronics Technologies EUV Lithography Laboratory Contents Background EUV-reflectivity measurement system Multilayer deposition system Evaluation of Mo/Si multilayer Summary
Background high-precision reflectometry of multilayer [dominant factors] wavelength calibration resolution elimination of stray light accuracy and repeatability of detector noise (detector or AMP...) goniometer construction of ASET beamline for EUV reflectometery resolution of grating repeatability of detector multilayer fabrication [dominant factors] high-reflectivity low-defect uniformity development of multilayer deposition system
ASET Beamline 10.5m Source: (NTT Super ALIS) SR light mirror 2 slit mirror grating slit mirror reflectometer
Reflectometer of Beamline 2θarm and detector (Si photodiode) SR scan modes 1) λscan θscan,2θscan 2) θ-2θscan 3) line scan (θ,2θ,λ fixed) sample mask blanks/mirror diameter: 200mmφ thickness: 50mm measurement modes reflectivity(multilayers) transmission(resist film) θarm and sample stage specification reproducability (Reflectivity) < R ±0.5%
EUV Reflectivity Measurement Flow Super-ALIS Io measurement Si photodiode(io) mirror Ring current(io) 13nm grating I measurement Si photodiode(i) Ring current(i) Super-ALIS Mo/Si multilayer mirror 13nm grating Reflectivity= (Si photodiode(i) /Ring current(i)) (Si photodiode(io) /Ring current(io))
Repeatability of Reflectivity-measurement Caused by Detector standard deviation/average value 1 Si photodiode 0.051% 2 ring current 0.016% condition ring current photodiode+amp Io measurement 350 ma 10.0 V I measurement 345 ma 5.91 V repeatability (σ) : 0.060% < 0.5% Specification repeatability
Spectral Resolution Spot diagram at exit slit λ=13nm Measured reflectivity as a function of resolution E/ΔE=4194 Reflectivity (%) 80 60 40 20 0 λ=13.5nm R(%) 10 100 1000 10000 E/ E This grating has enough resolution to measure multilayer reflectivity
Multilayer Deposition System [top-view] SMIF-POD Helicon cathode sputtering chamber [side-view] rotation wafer wafer robot wafer Sputter-up Helicon cathode L/UL chamber aligner transfer chamber cathode cathode
sputtering condition Mo Si Ar Pressure 0.20 Pa 0.07 Pa TEM cross section for (Mo/Si) multilayer surface Measured hard X-ray curve of (Mo/Si) multilayer 1.E+8 Power deposition rate 500W 1kW (DC) (RF) 0.4A /s 0.4A /s Intensity(a.u.) 1.E+6 1.E+4 1.E+2 substrate Si wafer (200mm) substrate 1.E+0 0 5 10 15 2θ (deg.) dark:mo layer light:si layer
EUV Reflectivity of (Mo/Si) Multilayer Reflectivity (%) 70 60 50 40 30 20 10 0 θ /2θ =3 /6 12 12.5 13 13.5 14 wavelength (nm) Reflectivity (%) 70 60 50 40 30 20 10 0 λ =13.2nm θ /2θ =3 /6 R=59.6±1.1% r=0-87mm R=60.2±0.3% r=0-60mm 0 30 60 90 distance from the center, r (mm)
Supersonic Hydro-cleaning Technique Liquid droplets impact into the substrate. Carrier gas Cleaning liquid Droplets (N 2 ) (deionized water) Nozzle designed for supersonic flow Substrate Microscopic phenomenon Side jet Droplet Side jet Twin-fluid supersonic flow Substrate Substrate High-speed side jets flow along the surface. This technique was developed at ASET SPC Laboratory. 5/18
Results before cleaning after cleaning Reflectivity (%) 70 60 50 40 30 20 10 0 12.5 13.0 13.5 14.0 14.5 wavelength (nm)
Summary EUV reflectivity measurement system can be applied to the evaluation of Mo/Si multilayer for mask blanks and mask fabrication process. EUV reflectivity of Mo/Si multilayer which was deposited by helico sputtering was measured using ASET Beamline. reflectivity : R > 60% R=59.6±1.1% r=0- in-plane 87mm distribution R=60.2±0.3% r=0-60mm
Acknowledgements This work is performed under the management of ASET in the program of the Ministry of International Trade and Industry (MITI). ASET is supported by the New Energy and Industrial Technology Development Organization (NEDO). The design and construction of ASET beamline and sputtering system was supported by Shimadzu Corp. and ULVAC JAPAN Ltd., respectively.