EUV Multilayer Fabrication Rigaku Innovative Technologies Inc. Yuriy Platonov, Michael Kriese, Jim Rodriguez ABSTRACT: In this poster, we review our use of tools & methods such as deposition flux simulation & ray-trace illumination modeling as applied to an extended history of EUVL coating projects. These methods offer insights into the successful fabrication of multilayers for all purposes, including analysis, specification determination, coating calibration and performance assessment. In our case, they have played a role our history of EUVL coatings: 2-Optic imaging system (1999) >1 Mask blanks (1999-2) 36mm Condensor (22) 2-Optic imaging system (23) 2-Optic toroidal imaging system (24) 6-Optic condensor/imaging system (25) Wideband & High-Selective EUV multilayers
Facility & Metrology 6 Carousel Magnetron & 1 Ion-beam 5-Target Inline Magnetron Loadlock, Linear Ion source, 4 process gas 5x15mm carrier /w velocity profiling Dual-substrate spinning: (45mm dia x1mm & 175mm dia x 35mm) Metrology: Grazing-incidence x-ray reflectometry (Cu Kα, 3 instruments) UV Spectrophotometer: 11-55 nm (refl & trans up to 2mm dia x 5mm thick) Profilometer Curvature (.5 arc-sec precision) AFM
Reflectivity.7 Reflectivity.6.5.4.3 λ P = 3 nm Rp =.6712 Mo/Si ML Ru/B4C Cap 2mm optic Inline.2.1 θ ~ 2.7 deg 12.8 13 13.2 13.8 14 14.2 Wavelength, nm SiC/Si ML High-Selective 13.5nm Reflectivity.35.3.25.2.15.1 θ=85deg. R=29.7%, fwhm=1.49a R=29.3%, fwhm=1.5a R=29.7%, fwhm=1.48a.5 Measured by Eric Gullikson at LBL, March 24 125 127 129 131 133 135 137 139 141 143 145 Wavelength, A Wide band pass Mo/B4C structures at 12keV. Theta=1 deg. Re fle ctivity.45.4.35.3.25.2.15.1.5 24655-8 5% bandpass 24659-8 1% bandpass Mo/B4C ML Wide-Band 12keV, 1deg 9 9.22 9.44 9.66 9.88 1.1 1.3 1.5 1.8 11 11.2 11.4 11.6 11.9 12.1 12.3 12.5 12.7 13 13.2 13.8 14.1 14.3 14.5 14.7 14.9 Photon energy, kev
Imaging Systems 2-Optic Imaging System (24) 2mm toroidal (R~35-6) 2D non-radial gradient Ru/B 4 C topcoat (best R p 67.1%) Achieve < ±1% wavelength on all four optics (2 sets of 2) variation of peak-position.1nm contours 6-Optic Condensor/Imaging (25) Tinsley/Exitech RIM 4 condensor (1 Ru, 3MoSi) 2 imaging (MoSi) Added Figure Error in imaging optics: M1:.15nm (±.18nm λ in CA) M2: <.1nm (±.5nm λ in CA)
Imaging Systems Schwarzschild Imaging (23) Median Wavelength {at the prescribed incidence angle} 14 138 136 134 132 Large Concave: Measurements of Diametric Radii Average of all 28 measurements: 134.999Å Peak-to-Valley Range across diameter: 1.15Å RMS Deviation from Target: ±.33Å 13 2 3 4 5 6 7 8 9 Radius (mm) Peak Reflectivity.7.68.66.64 Large Diameter Concave Optic R P =.93% absolute (Peak-to-Valley).62.6 2 3 4 5 6 7 8 9 Radius (mm) 6-Optic Condensor/Imaging (25) Tinsley/Exitech RIM 13.55 M1 Optic 13.55 C1,C3 Optics 13.5 13.5 5 5 5 1 15 2 25 3 35 4 45 Radius, mm (radially symmetric) 13.55 M2 Optic 13.5 5 2 4 6 8 1 12 14 Radius, mm (radially symmetric) -2-15 -1-5 5 1 15 2 Across diameter, mm (more uniform in orthogonal) 13.55 C2 Optic 13.5 5 2 3 4 5 6 7 8 Across CA, mm (radially symmetric) Shape Curvature Diameter CA Radii λ C (PV) thick (PV) thick (rms) M1 Concave moderate 155mm 1-45mm ±.18nm ±.38nm.23nm M2 Convex moderate 78mm 3-12mm ±.5nm ±.1nm.4nm C1 Concave moderate 42mm -16mm ±.13nm ±.26nm.2nm C2 Convex very curved 18mm 3-7mm ±.22nm ±.45nm.37nm C3 Concave flat 25mm -6mm ±.4nm ±.1nm.8nm C4 Flat -n/a- 4mm -18mm -n/a- ±.3nm -n/a-
Deposition Simulation 36mm Condensor: 2D Graded Ellipse Deposition across the optic from a specific range of travel within the chamber 3 ML Period Deposition Rate, Å/sec 2.5 2 1.5 1.5-2 -15-1 -5 5 1 15 2 Radial distance from vertex, mm Non-radial on sphere Uniform on cylinder
Deposition Simulation Effective Period of Multilayer, Å 36mm condensor: before utilizing velocity control 84 8 no spinning 76 72 68 64 6-2 -15-1 -5 5 1 15 2 Radial distance from vertex, mm Effective Period of Multilayer, Å 36mm condensor: after utilizing simulation-based solution for velocity profile 82 8 78 76 74 72 7 68 66 no spinning -2-15 -1-5 5 1 15 2 Radial distance from vertex, mm
Ray-Tracing ML impact to system illumination Source has spectrum I O (λ) Multiple beams (N) exit from each position, x S, on the source Each position of the source illuminates the entire width of the reticle/detector image; it images a subset of positions, x M, across the clear-aperture on each optic (M optics). The variation of the reflectivity spectra, R(λ), on each optic is known. Functionalize the variation in peak wavelength with position ( λ P vs x) Each ray has a different angle-of-incidence, g, on each optic. This value is different from the measurement angle, g m, of the multilayer. The peak is shifted λ g from the g m to g. λ γ = f cos( γ ) cos( γ m).6.4.2 13 13.5 14 I( x) = 2 N λ λ 1 I o ( λ) R M ( x M measured 4.32º shifted to 5.76º, λ[ λ mfg, λ γ vs γ m ]) Relative Illumination Intensity The source spectrum and the optic reflectivity spectra are multiplied and integrated in the bandwidth for each beam. The multiple N beams arriving at each reticle/detector position are then summed. Multi-reflection Reflectivity.1.8.6.4.2 Illumination Variation to the Detector (various scenarios).14.135.13.125 13 13.2 13.8 Wavelength, nm.12-1 -.5.5 1 Relative Position Across Image.8.6.4.2 Relative Intensity of Source (black) How does illumination vary across reticle/detector? How does I(x) change from assumption of perfect coatings (identical & perfect uniform R(λ)) with actual measured spectra? Is there an effect of the actual source spectrum I o (λ) from some idealized constant value? What are individual effects of λ & Rp variations in the ML coatings? What are the relative contributions to I(x) of each optic? With known expectations or prior results of coatings, can you make tradeoffs in total illumination (I avg ) vs illumination variation ( I) by changing the targeted specifications of individual optic-coatings?
CD-SAXs Camera line-edge roughness 25 Int l EUVL Symposium (San Diego)