Tools to draw
kinds of lithography
Embedded Files
After the resist is applied to the substrate, one can start "drawing". In our case, to form the desired image, irradiating the resist in the right areas.ย Depending on the type of radiation used - a tool for "drawing" - there are types of lithography.ย
Photolithography.ย ย
Photolithography.ย ย
The resist is exposed by light of a certain wavelength.ย A pre-made mask is used (a glass plate with opaque - chrome covered - areas that form the necessary pattern).ย Light from a special source, passing through the mask, enters the system of lenses that focus the image of the mask on the surface of the resist.ย The principle of operation is like printing photos from film.ย The difference is when printing photographs, the image from the film is transferred to photo paper with magnification, and in photolithography, the image of the mask is transferred to the resist with decrease.ย
And one more thing: mask pattern is repeated many times on substrate during lithography. Exposing the substrate step-be-step: one (small) area is exposed, then substrate shifts on one "step", exposed again... etc. (Therefore, the apparatus for lithography exposure called stepper).ย
EUV-ะปะธัะพะณัะฐัะธั.
EUV-ะปะธัะพะณัะฐัะธั.
EUV is "extreme ultraviolet" with a wavelength (over) 10 times shorter than in "conventional" photolithography. It is impossible to create lenses for such radiation: any glass absorbs EUV very strongly. The glass base of the mask also becomes opaque. Thus, all optical elements in EUV lithography (mask and reduction/focusing system) are multilayer mirrors.
X-ray lithography.
X-ray lithography.
With a decrease in the radiation wavelength another ~10 times, we pass into the X-ray region. Because of the specifics of the interaction of X-ray radiation with matter, only lithography with no focusing elements is really possible. That is, one-to-one reproduction of the mask pattern (without reduction). Problems with the radiation source, secondary exposure of the resist by high-energy photoelectrons, and many technical difficulties exclude X-ray lithography from the industrial competitors of photo- and EUV-lithography.
Electron-beam lithography.ย ย
Electron-beam lithography.ย ย
The resist is exposed by a thin focused beam of electrons. The electromagnetic control system allows the beam to be precisely positioned on the surface of the resist. The exposure of the resist occurs in the same way as an electron beam forms an image in (already old) TVs, "running" around the screen. There are multibeam systems where several beams of electrons simultaneously "draw" in different parts of the surface of the resist.
Currently, photo-, EUV- and e-beam lithography are actually used. They - differing in their capabilities - complement each other well in the huge and complex world of the semiconductors / electronics industry, bringing together various industries and research centers. Each type of lithography has its niche.ย
Currently, photo-, EUV- and e-beam lithography are actually used. They - differing in their capabilities - complement each other well in the huge and complex world of the semiconductors / electronics industry, bringing together various industries and research centers. Each type of lithography has its niche.
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