The Rayleigh criterion
The resolution equation that determines just how small the features on a chip can be printed
CD = k1 • λ / NA
Rayleigh criterion equation
In the Rayleigh criterion equation,CD是个critical dimension, or smallest possible feature size, andλ是个wavelengthof light used.
NA是个数值孔径of the optics, defining how much light they can collect.
Finally,k1(or thek1因素）是一种系数，其取决于与芯片制造过程相关的许多因素。物理极限光刻是k1= 0.25。
Smaller critical dimension can be achieved by using a combination of smaller light wavelength and larger numerical aperture (NA), while pushing k1尽可能接近物理限制。
Much of the R&D in the semiconductor industry is focused on reducing critical dimension. ASML’s lithography machines print at extremely high resolution, helping chipmakers to decrease this critical dimension further.
More advanced microchips mean smaller features, which need shorter wavelengths of light, more powerful lenses and / or a lower k1因素. Reducing the light wavelength is a major technology shift that requires new lithography machines with new light sources – as well as new (optical and resist) materials and new processes. But it also brings the biggest strides forward in in chip performance.
More about ASML technology
Providing highest resolution in high-volume manufacturing, ASML’s extreme ultraviolet lithography machines are pushing Moore’s Law forward.