E-beam lithography is one of the most effective methods for the fabrication of polymers. E-beam fabrication involves a beam of high-velocity electrons, which is applied to the materials to be fabricated. The high-velocity electrons cause the workpieces to melt and flow together, as the electrons’ kinetic energy is transformed into heat upon impact.
Ideally, Electron beam lithography is not only one of the most common technologies used for patterning at the nanoscale range. The technology has enabled the fabrication of structures and devices within the fields of nanotechnology and nanoscience. To understand how e-beam lithography is important in fabrication, we first look at how the technology works.
An Overview of How E-Beam Lithography Works
Often abbreviated EBL, E-Beal lithography is based on sub-micronic features and works by scanning the focused, energetic beam of electronics on a resist. Therefore, the nature of the electrons and the development of magnificent beams and flexible control enables the technique to satisfy nanofabrication requirements.
Lithography continues to play a critical role in fabrication. As a result, technology has enabled the manufacturing of a wide range of nanostructures, nanodevices, and nanosystems. Besides, E-beam fabrication is essential in prototyping and manufacturing discrete devices critical to fundamental research.
For electron-beam heating, free electrons are accelerated with their electric and magnetic fields’ paths. Therefore, the narrow beams of electrons that carry high kinetic energy are formed, and upon collision with the atoms in solids, transform their kinetic energy into heat.
What makes E-Beam lithography a perfect choice for fabrication?
There are different reasons why EBL is the right solution when it comes to fabrication. Here is an overview of some of the reasons to use the E-Beam lithography for fabrication:
- Features strong electric fields: the strong electric fields come with the ability to accelerate the electrons to a very high speed. Therefore, the electron beam carries a high power equal to the beam current and accelerates voltage. The beam power is increased to practically and desired value by increasing the beam current and accelerating voltage.
- The magnetic lenses shaped the beam into a narrow cone and focused to a small diameter. This allows the high surface power density on the surface to be welded.
- Shallow penetration depth in the order of hundredths of a millimeter allows a high volumetric power density. Consequently, the temperature in the volume increases exceptionally rapidly.
However, note that the effectiveness of the e-beam lithography depends on various factors. The most important feature is the physical property of the material to be fabricated. This is concerning the ease with which the material can be melted or vaporized under the low-pressure conditions.
Electron-beam fabrication can get so intense, leading to the loss of material because of evaporation or boiling during the process. Therefore, at the lower values of the surface power density, the loss of material through evaporation is negligible for different materials.
Penetration of E-Beam During Fabrication
To understand the electron beam’s capability to produce the deep and narrow welds, we need to explain the process of electron beam penetration during fabrication. Here is an overview of the penetration of the electron beam.
The heat contribution of single electrons can be minimal. However, a very high voltage can accelerate the electrons. By increasing the number of electrons, the power of the beam is raised to the desired value. Therefore, focusing the beam onto a small diameter on the object’s surface, power density values can be reached. Since the electrons transfer their energy into heat in a thin layer of the solid, the volume’s lower density can be too high.
Under such circumstances, the effect of the electrons beam depends on various conditions. The first determinant is the physical properties of the material. Therefore, at lower values of the surface power density, the loss of material through evaporation is negligible, as explained above. This is favorable for fabrication. At the high power density, the materials affected by the beam of electrons will evaporate totally within a short period, causing a situation commonly referred to as electron-beam machining.