Lithography resolution and depth of focus calculator (Rayleigh criterion)
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KEY POINTS
The smallest feature lithography can print follows the Rayleigh equation R = k₁ × λ / NA, and depth of focus follows DOF = k₂ × λ / NA². Resolution improves with a shorter wavelength λ, a larger numerical aperture NA and a smaller process factor k₁, but raising NA shrinks depth of focus with its square. This tool lets you check that trade-off in numbers.
Inputs
k₁ reflects how far resolution enhancement techniques (OPC, phase-shift masks, off-axis illumination) have been pushed; the theoretical limit for a single exposure is 0.25. k₂ is around 0.5 depending on how depth of focus is defined. A higher NA improves resolution, but depth of focus shrinks with the square of NA.
FAQ
What is the resolution of EUV lithography?
With λ = 13.5 nm, NA = 0.33 and k₁ = 0.4, R = k₁λ/NA is about 16 nm. High-NA EUV with NA = 0.55 gives about 10 nm at the same k₁.
What is the lowest possible k₁?
The theoretical limit for a single exposure is 0.25. Below that, features have to be split across several exposures (multiple patterning).
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Last updated: October 23, 2026