Rayleigh equation relates the critical dimension of a process to the numerical aperture and wavelength of the imaging system.

Etymology

The equation is named after John William Strutt, 3rd Baron Rayleigh (Lord Rayleigh) (November 12, 1842 - June 30, 1919), a well-known physicist and Nobel laureate whose original formulation formed the foundation for the modern variant as used by modern lithography.

Overview

Rayleigh equation relates the critical dimension of a process technology to the numerical aperture and wavelength of the imaging system. In other words, the smallest dimension printable on a chip is a function of the wavelength of the light and the numerical aperture (quality) of the lens.

Where:

• - critical dimension of the technology
• - wavelength of the imaging system
• - numerical aperture of the lens
• - k1 factor; dimensionless, process-dependent, constent

The equation shows that to make smaller features one can use either a smaller wavelength of light or better lenses.

See also

• deep ultraviolet lithography (DUV)
• extreme ultraviolet lithography (EUV)