Electron Beam Evaporation: Overview A strong magnetic field focuses the electrons into a unified beam; upon arrival, the energy of this beam of electrons is transferred to the deposition material, causing it to evaporate (or sublimate) and deposit onto the substrate.
What is electron beam evaporation?
E-Beam evaporation is a physical vapor deposition (PVD) technique whereby an intense, electron beam is generated from a filament and steered via electric and magnetic fields to strike source material (e.g. pellets of Au) and vaporize it within a vacuum environment.
Why electron beam is used in evaporation?
The electron beam is accelerated to a high kinetic energy and focused towards the starting material. The kinetic energy of the electrons is converted into thermal energy that will increase the surface temperature of the materials, leading to evaporation and deposition onto the substrate.
What are the disadvantages of e-beam evaporation?
1.) Evaporation: Advantages: Highest purity (Good for Schottky contacts) due to low pressures. Disadvantages: Poor step coverage, forming alloys can be difficult, lower throughput due to low vacuum.
What is an electron beam?
Listen to pronunciation. (ee-LEK-tron beem) A stream of electrons (small negatively charged particles found in atoms) that can be used for radiation therapy.
What is an electron beam source?
Electron beam deposition is a method of using electron beams generated from an electron source in a vacuum to irradiate an evaporant material, and heating and evaporating it so that the evaporated material forms a thin film on a substance, such as a substrate or a lens.
How does electron beam work?
Electron beams are particle accelerators. Electrons are generated by heating a filament. A voltage gradient draws the electrons away from the filament and accelerates them through a vacuum tube. The resultant beam can then be scanned by means of an electromagnet to produce a “curtain” of accelerated electrons.
What is the source of the electron beam?
Thermionic emission of electron Thermionic sources rely on heat to generate electrons, similar to how light is produced by incandescent lightbulbs. As a current is applied to the filament (or crystal), it is progressively heated until its electrons have enough energy to escape the solid surface.
What are the advantages of an electron beam evaporator compared to a thermal evaporator?
1) Electron beam evaporation can heat materials to a higher temperature than thermal evaporation. This allows very high deposition rates and evaporation of high temperature materials and refractory metals such as tungsten, tantalum or graphite. 2) E-beam evaporation can deposit thinner films with higher purity.
What are the advantages of e-beam evaporation over regular thermal evaporation technique?
Overview of E-Beam Evaporation
- Good for metals and dielectrics with high melting points.
- Excellent uniformity if you are using planetary and masks (but poor without)
- Low level of impurity.
- High deposition rate of <100 Å/s (better than sputtering or resistive thermal evaporation) for high throughput.
- Good directionality.
How are electrons produced?
Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.
What is the temperature of an electron beam?
Electrostatic and magnetic fields focus and direct the electrons to strike a target. The kinetic energy is transformed into thermal energy at or near the surface of the material. The resulting heating causes the material to melt and then evaporate. Temperatures in excess of 3500 degrees Celsius can be reached.
What is the electron beam evaporation process?
The electron beam (E-beam) evaporation process is a physical vapor deposition that yields a high deposition rate from 0.1 μm/min to 100 μm/min at relatively low substrate temperatures.
What is therthermal evaporation?
Thermal evaporation is one of the simplest forms of physical vapor deposition. In this process, a resistive heat source is used to evaporate a solid material in a vacuum environment to form a thin film. The material is heated in a high vacuum chamber until vapor pressure is produced.
How can I deposit non-metallic film using electron beam evaporation?
Adding a partial pressure of reactive gas, such as oxygen or nitrogen to the chamber during evaporation can be used to reactively deposit non-metallic films. Electron beam evaporation has many advantages over resistive thermal evaporation.
What are the advantages of e-beam evaporation?
Electron Beam Evaporation can yield significantly higher deposition rates – from 0.1 nm per minute to 100 nm per minute – resulting in higher density film coatings with increased adhesion to the substrate. E-Beam Evaporation also has very high material utilization efficiency compared to other PVD processes reducing costs.
