Electron-Beam Lithography To pattern 10nm feature, what do you prefer to use? bu

Question

Electron-Beam Lithography To pattern 10nm feature, what do you prefer to use? bullet Photolithography. bullet Electron-beam lithography What is back scattering, how the back scattering impact resolution? (there are two correct answers choose two answers) bullet Electrons undergo small angle collisions to re-emerge into the resist at a small distance from the incident beam. Back scattering contributes a small area fog of exposure. bullet Electrons undergo large angle collisions to re-emerge into the resist at a large distance from the incident beam. Back scattering contributes a large area fog of exposure. bullet Back scattering improves resolution. bullet Back scattering limits resolution. What is forward scattering how the forward scattering impact resolution? (there are two correct answers, choose two answers) bullet As electron beam enters the electrons are deflected largely, effectively narrowing the initial beam diameter. bullet Forward scattering reduces resolution. bullet As electron beam enters the electrons are deflected slightly, effectively broadening the initial beam diameter D bullet Forward scattering improves resolution. What is second electron generation, how the second electron generation impact resolution? (there are two correct answers, choose two answers) bullet The primary incident high energy electrons collide with resist and create low energy secondary electron. bullet The primary incident high energy electrons collide with resist and create high energy secondary electron bullet Second electron generation limits resolution. bullet Second electron generation improves resolution. bullet Can we write 10nm lines when the beam width is 10mm? why? bullet We can write 10nm lines using the beam width of 10nm, because forward scattering, back scattering and generation of secondary electrons improves resolution. bullet we can't write 10nm lines using the beam width of 10nm, because forward scattering, back scattering and generation of secondary electrons limit resolution. bullet we can't write 10nm lines using the beam width of 10nm, because forward scattering, back scattering and generation of secondary electrons improve resolution.

Explanation / Answer

a) For 10 nm feature use EBL

EBL resolution - sub 10 nm. It depends on the type of the resist used, the thickness of the resist, the type of substrate, and the operating conditions.

Photolithography resolution ~15 nm. It most importantly depends on wavelength and numerical aperture

b) 2nd option and 4th option - large angle , limit resolution

In backscattering, an electron collides with the much heavier nucleus, which results in an elastic scattering event. The electron retains (most of) its energy, but changes its direction. The scattering angle may be large in this case. After large angle scattering events in the substrate, electrons may return back through the resist at a significant distance from the incident beam, thereby cause additional resist exposure. This backscattering is what causes the proximity effect where electrons writing a feature at one location increase the exposure at a nearby feature, causing pattern distortion and overexposure to limit the resolution.

c) 3rd option and 2nd option - increase diameter and limit resolution

In forward scattering, an electron can collide with an electron from one of the atoms in the substrate/resist. The incident electron will change its direction and transfer part of its energy to the atom. Because of the extra energy, the atom will become exited (one of its electrons goes to an exited level) or ionized (one electron leaves the atom, creating a secondary atom in the material). When the target atom is part of a resist molecule, the molecular chain may break due to this excitation or ionization. The scattering angle due to inelastic scattering is, as a rule, small.

this type of scattering increases the effective beam width at the bottom of the resist layer. It is also responsible for proximity effect

d) 1st and 3rd option - low energy electrons, limit resolution

second electrons are low energy (a few to a few tens of eV) electrons produced by ionizations resulting from inelastic collisions by the primary incident electrons. secondary electrons have short range (several nanometers) but may ultimately limit the resolution possible with EB

e) 2nd option Can'twrite, limit resolution

As explained above , scattering and electrons limit resolution

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