Ion-beam lithography is the practice of scanning a
focused beam of ions in a patterned fashion across a surface in order to create very small structures such as
integrated circuit
An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
s or other
nanostructure
A nanostructure is a structure of intermediate size between microscopic and molecular structures. Nanostructural detail is microstructure at nanoscale.
In describing nanostructures, it is necessary to differentiate between the number of dimen ...
s.
Details
Ion-beam lithography has been found to be useful for transferring high-fidelity patterns on three-dimensional surfaces.
Ion-beam lithography offers higher resolution patterning than UV, X-ray, or electron beam lithography because these heavier particles have more momentum. This gives the ion beam a smaller
wavelength
In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats.
In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...
than even an e-beam and therefore almost no diffraction. The momentum also reduces scattering in the target and in any residual gas. There is also a reduced potential radiation effect to sensitive underlying structures compared to x-ray and e-beam lithography.
Ion-beam lithography, or ion-projection lithography, is similar to
Electron beam lithography
Electron-beam lithography (often abbreviated as e-beam lithography or EBL) is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electron-sensitive film called a resist (exposing). The electron ...
, but uses much heavier charged particles,
ions. In addition to diffraction being negligible, ions move in straighter paths than electrons do both through vacuum and through matter, so there seems be a potential for very high resolution. Secondary particles (electrons and atoms) have very short range, because of the lower speed of the ions. On the other hand, intense sources are more difficult to make and higher acceleration voltages are needed for a given range. Due to the higher energy loss rate, higher particle energy for a given range and the absence of significant space charge effects,
shot noise
Shot noise or Poisson noise is a type of noise which can be modeled by a Poisson process.
In electronics shot noise originates from the discrete nature of electric charge. Shot noise also occurs in photon counting in optical devices, where s ...
will tend to be greater.
Fast-moving ions interact differently with matter than electrons do, and, owing to their higher momentum, their optical properties are different. They have much shorter range in matter and move straighter through it. At low energies, at the end of the range, they lose more of their energy to the atomic nuclei, rather than to the atoms, so that atoms are dislocated rather than ionized. If the ions don't defuse out of the resist, they dope it. The energy loss in matter follows a
Bragg curve and has a smaller statistical spread. They are "stiffer" optically, they require larger fields or distances to focus or bend. The higher momentum resists space charge effects.
Collider
A collider is a type of particle accelerator that brings two opposing particle beams together such that the particles collide. Compared to other particle accelerators in which the moving particles collide with a stationary matter target, collid ...
particle accelerator
A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies to contain them in well-defined particle beam, beams. Small accelerators are used for fundamental ...
s have shown that it is possible to focus and steer high momentum charged particles with very great precision.
See also
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E-beam lithography
Electron-beam lithography (often abbreviated as e-beam lithography or EBL) is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electron-sensitive film called a resist (exposing). The electron ...
*
Maskless lithography
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Nanochannel glass materials
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Photolithography
Photolithography (also known as optical lithography) is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer.
The process begins with a photosensiti ...
References
{{DEFAULTSORT:Ion Beam Lithography
Semiconductor device fabrication