Electron Beam Lithography is the practice of scanning a focused beam of electrons to write a custom shape on the electron sensitive resist film. This article elaborates on the advantages and disadvantages of electron beam lithography systems. We begin with the advantages:
Advantages of Electron Lithography
- Allows printing of complex patterns directly on the wafers
- Useful technology when it comes to elimination of diffraction problems
- Comes with a high resolution of up to 2o nm
- Features a flexible technique
Just like other technologies, EBL features advantages and disadvantages. Having looked at the advantages, now we shift the attention to disadvantages.
So, what are the disadvantages of electron beam lithography?
- The Electron beam lithography systems are slower than the optical lithography
- The technology is expensive and complicated
- Features forward scattering
- Associated with backscattering
- Uses secondary electrons
Why use the Electron Beam Lithography Systems?
Despite the disadvantages mentioned above, there are various reasons why EBL technology is relevant. To begin with, the EBL technology features Ions with a heavy mass than the electrons. Secondly, the technology features fewer proximity effects due to backscattering but comes with a less scattering effect compared to other technologies. The EBL technology has a higher resolution patterning than the UV, X-ray, or electron beam lithography because the heavier particles feature more momentum. Therefore, the ion beam comes with a smaller wavelength than even the e-beam and has almost no diffraction.
Ideally, the Electron Beam is used primarily for two purposes. Firstly, the EBL technology is used for very high-resolution lithography and for the fabrication of masks through the etching process. Having mentioned the primary application areas, it is worth noting that it uses the Serial Lithography System.
What Are the Sources of the Electron Beam?
Before we come to the advantages and the disadvantages of Electron Beam Lithography, it is important we elaborate on the various sources of the electron beam. The electron beam sources include:
- Thermionic Emitters: This features the Electrons released due to the thermal energy.
- Photo Emitters: which occurs due to the incident radiations or the photons
- Field Emitters as a result of applied current and quantum mechanical property of electrons.
To understand how the electron beam lithography systems work, here is an overview of EBL procedures:
Step1. A Sample is coated with a thin layer of resist, referred to as polymethylmethacrylate, abbreviated as (PMMA).
Step2. The PMMA breaks down into monomers upon exposure to the electrons.
Step3. The exposed regions will be rinsed away through the use of chemical
Therefore, electron lithography involves a much slower process compared to optical lithography technology. The electron beam lithography system features a complex machine structure. The machine structure comprises of various components. Here is an overview of the components that make up the electron lithography:
- Electron gun
- Beam blanker
- Deflection Coils or lenses
- Vacuum chamber
The electron coils and lenses are used for focusing the electron. The beam blanking is important in turning the electron beam on and off. Another important component is the stigmata, which is a special type of lens that is used for compensating imperfections in the construction and the alignment of the EBL column. The vacuum is important for isolating the electron beam from the interferences.
We have looked at the advantages and disadvantages of electron beam lithography systems. While the EBL technology involves much slower processes, the technology is used widely in various applications.