Basic Principle
The basic principle is the same as in interferometry or holography. An interference pattern between two or more coherent light waves is set up and recorded in a recording layer (photoresist). This interference pattern consists of a periodic series of fringes representing intensity minima and maxima. Upon post-exposure photolithographic processing, a photoresist pattern corresponding to the periodic intensity pattern emerges.
For 2-beam interference, the fringe-to-fringe spacing or period is given by (λ/2)/sin(θ/2), where λ is the wavelength and θ is the angle between the two interfering waves. The minimum period achievable is then half the wavelength.
By using 3-beam interference, arrays with hexagonal symmetry can be generated, while with 4 beams, arrays with rectangular symmetry are generated. Hence, by superimposing different beam combinations, different patterns are made possible.
Read more about this topic: Interference Lithography
Famous quotes containing the words basic and/or principle:
“The basic tool for the manipulation of reality is the manipulation of words. If you can control the meaning of words, you can control the people who must use the words.”
—Philip K. Dick (1928–1982)
“Thanks to all. For the great republic—for the principle it lives by, and keeps alive—for man’s vast future,—thanks to all.”
—Abraham Lincoln (1809–1865)