Vertical Electron Beam Evaporators EBVV allow introducing real e-beam evaporation into many growth systems originally designed for radiation heated effusion cells only. Despite its small footprint, the EBVV features a complete electromagnetic x- and y-dynamic beam deflection system and is capable of delivering beam powers up to 3kW @ 6kV.
Its unique and extremely compact design makes it possible to install the EBVV instead of an ordinary effusion cell onto any MBE system having a (near) vertical DN63CF port with I.D. >= 60mm. Inclined ports can be used without any difficulty for sublimating crucible charges. For materials that become liquid during operation EBVV evaporators are available with a tilted hearth geometry on request.
Especially for hot parts only UHV-grade materials are used without any compromise: molybdenum emitter block, tungsten filament and Al2O3 insulting ceramics. The main body is manufactured from OFHC (Oxygen-Free High Conductivity) copper and closely surrounded by a complete turn of an Ω-shaped water channel for most effective cooling.
Two different hearth volumes are available: the 4 cm3 (O.D. 22mm, taper 15°) geometry is compatible with standard crucible liners, while the 5 cm3 (O.D. 23mm, taper 12°) model is recommended for Si epitaxy (in combination with specially adapted silicon shielding parts).
The 270° beam deflection design of the electron emitter eliminates nearly all ion bombardment on the filament, due to a sharply bent electron beam path near the beam exit aperture. In this way, the filament is well shielded from evaporant or charged particles ejected from the crucible. In addition, the sample is shielded from direct sight onto the hot tungsten filament, further reducing the chance of sample contamination by impurities from the hot emitter area.
EBVV 63-4, view onto emitter block and filament
The small dimensions and the vertical evaporator design open the path to a new range of applications:
In standard MBE systems and the majority of home-made UHV chambers there are often no horizontal ports designated for typical e-beam evaporators. Here the compact design of the EBVV allows the integration of a powerful electron beam evaporator into virtually every UHV growth system.
The EBVV closes the gap between small rod-fed e-guns, usually providing very low fluxes and only suitable for sublimating evaporants, and common horizontally mounted e-beam evaporators, which often are excessively space-consuming and far overrated for most MBE applications. EBVV evaporators may even be a good alternative to radiation heated high temperature sources running into their flux. temperature or purity limits
The EBVV is the ideal evaporator for any low or very low vapor pressure material, including refractory metals or dopants like, for example, boron or carbon. It can also serve the upcoming demands in newly developed material systems like high-k materials (Al2O3 or Pr3O3) or other oxides and dielectrics.
For metal deposition the EBVV 63-4 can be used with bare copper hearth, in particular for all metals that do not melt completely (e.g., Al) or that are not reacting with the cooled copper wall. Crucible liners manufactured from graphite or refractory metals are available for other materials. Please inquire about a solution for your particular evaporation material.
For Boron doping applications we offer the specialized e-beam evaporator type EBVV-B.
EBVV 63-5, pool of molten silicon (EBVV is mounted into a port 35° to the vertical axis)
Silicon shielding parts for SiGe MBE
SiGe MBE is another key application for the EBVV. For Si growth in an MBE system the use of the EBVV 63-5 is recommended because hearth capacity and geometry are optimized for this special application.
A set of specially adapted shielding parts manufactured from high purity single-crystalline Si is available for this model. All parts of the metallic body that are potentially subject to electron or ion bombardment and that face the substrate are covered by a top Si plate and ring. This kind of shielding is a qualification for the growth of highest purity Si-based films with virtually no metallic contamination. The set is complemented by a high purity Si charge, source material in superior quality machined from wafer-grade Si single crystals, that fits the hearth closely.
EBVV 63-5, with shielding parts
Set of silicon shielding parts for EBVV 63-5
DN63CF (O.D.4,5“) or DN100CF (O.D.6“)
Dimensions in UHV
L=234-400 mm; D=60 mm
H=15 mm; Ø=22 mm (15° taper) or Ø=23 mm (12° taper)
5 mm diameter, approx.
Primary beam deflection
270° by permanent magnet system
Min. water flow rate 5 l/min at 4 bar
Tilted hearth (T); integrated rotary shutter (S)
Schematic drawing of the Vertical Electron Beam Evaporator EBVV
(drawing shows EBVV 63-5)