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Rayleigh Photolithography Resolution Calculator engineering
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Rayleigh Photolithography Resolution Calculator

Semiconductor microelectronics & advanced patterning: Compute critical dimension (CD) resolution, depth of focus (DOF), and process window across DUV, ArFi, and EUV lithography systems.

Lithography Exposure System

Standard fab stepper/scanner
Optical radiation wavelength
Projection lens NA = n · sin(θ)
Air/Vacuum = 1.0, Ultrapure water = 1.44
Theoretical limit = 0.25 (single exposure)
Focus process latitude constant

Patterning Limit & Focal Margin

Critical Dimension (Resolution R)
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-
Depth of Focus (DOF)
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DOF = k₂ · λ / NA²
Illumination Half-Angle (θ)
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sin⁻¹(NA / n)
Minimum Dense Pitch (2R)
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Single-patterning line/space
Photon Energy (E)
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E = hc / λ
Process Difficulty Index
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k₁ proximity to 0.25 limit

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Frequently Asked Questions

Why does increasing NA reduce Depth of Focus so dramatically?

Resolution scales inversely with NA (1/NA), but Depth of Focus scales inversely with the square of NA (1/NA²). Doubling NA halves the feature size but cuts usable focal depth by a factor of 4, requiring atomic-level wafer flatting (CMP) and extreme autofocus precision.

What is High-NA EUV?

Standard EUV scanners use 0.33 NA optics, resolving down to ~13 nm half-pitch. High-NA EUV increases the numerical aperture to 0.55 using anamorphic magnification (8× in y, 4× in x) to reduce critical dimensions to 8 nm without requiring multi-patterning.

How does immersion lithography achieve NA > 1.0?

Numerical aperture is defined as NA = n · sin(θ). In dry lithography, the maximum theoretical NA is bounded by the refractive index of air (n = 1.0). Immersion lithography places ultra-pure deionized water (n = 1.44 at 193 nm) between the final lens element and the wafer, enabling hyper-NA systems up to NA = 1.35.