Electron beam lithography, often known as e-beam lithography, is a method that uses a focused electron beam to create patterns on a substrate. An electron-sensitive layer, also known as a resist, is applied to the substrate\'s surface. It doesn\'t deposit the material on the surface; rather, it alters the solubility of the resist that is already there. The solubility of the resist varies when it is subjected to an electron beam, allowing it to be selectively removed.
Depending on the resist, the exposed part of the unexposed section becomes more soluble. The resist may be washed away by soaking it in a solvent, a process known as \'developing.\' Small details are generated in the resist, like photolithography.
The difference between optical and electron beam lithography
Unlike optical lithography, which employs photomasks to project patterns, an EBL system no longer requires masks to do its duty due to the advent of technology that allows a small-diameter focused beam of electrons to be scanned over a surface. Using the electron beam as a drawing pen, an electronic beam lithography system draws the design across the resist wafer. As a result, electronic beam lithography systems generate the resist pattern serially, making them slower than optical systems.
The following are the components of a typical EBL system:
1. An electron gun or source of electrons.
2. An electron column that shapes and focuses the electron beam.
3. A mechanical stage that positions the wafer under the electron beam.
4. A wafer handling system that automatically feeds and unloads wafers after processing; and
5. A computer system that monitors and controls the equipment
Diffraction limits the resolution of optical lithography, although this is not an issue with electron lithography. This is the electrons\' short wavelengths (0.2-0.5 angstroms) in the energy range EBL devices utilize. Other issues, such as electron scattering in the resist and various aberrations in the electron optics, can limit the resolution of an electron lithography system.