Four Common Electron Beam Source Problems and Solutions
Since the 1970s, electron beam ("E-Beam" or "EB") sources (or "guns") have been commonly used to desposit ultra thin films to assist in manufacturing a variety of products including optical filters and semiconductor circuits. E-beam sources exhibit high depostion rates and broad coverage area, and are an excellent choice for many industrial coating applications.
Four common problems and solutions:
1) Short filament life.
The electron beam is formed by energizing a filament under vacuum using high voltage DC power. If you can look straight down at your e-gun and see the filament, you are using what is referred to as a 180o source. Particles and flakes tend to collect near the filament and cause arcing. As the filament is in line of sight to the process plume, the material in your crucible often finds its way to the filament also. A 270o gun protects the filament.
2) Excessive arcing during deposition.
In particular when doing e-beam deposition in a hostile environment such as a "dirty" chamber, high oxygen content, and/or along side an ion source, excessive arcing is a common problem. Some e-beam sources are modified specifically for these applications, and are called "low arcing" or "arc-less" sources. For more information: http://www.telemark.com/electron_beam_sources/arc_suppression.php?cat=1&id=Arc+Suppression+Sources
3) Excessive beam curl.
Because the beam travels 270 degrees, it tends to reach the material to be deposited and then quickly starts to curl before reaching the lower portion of the material. This causes inefficient melting of the material, poor material distribution, and more frequent material changes. Technical advances have been made to extend the beam in a straighter path through the hearth and thus significantly reduce these problems.
4) Inconsistent spot size and shape.
Most e-beam sources produce a spot which changes in shape from front to back as it is moved around the hearth by the sweep controller, with the spot increasing in size as it approaches the front of the pocket. With the latest e-beam source designs, beam spot size and shape remains significantly more consistent throughout the hearth.
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