Electron Beam Evaporator EBV

• UHV compatible, low outgassing
• High flux rates of low vapour pressure materials
• High-purity evaporation
• Hearth volumes: 40 cm³, 100 cm³, 160 cm³ or 1000 cm³
• Long filament lifetime
• Easy maintenance
• Optimized versions for SiGe MBE available  Datasheet

Introduction

The standard Electron Beam Evaporator EBV is an evaporation source intended to achieve high growth rates for low vapour pressure materials, especially when high purity of the evaporant is desired. Large hearth capacities ensure a long system up-time before evaporant is depleted.
Our series of standard electron beam evaporators EBV are single-pocket UHV evaporators mounted horizontally on base flanges from DN200CF up to DN300CF. For all models a mounting-slide is offered that allows easy handling and service of the EBV.

Only UHV-grade materials are used for its construction without any compromise, obtaining a design that is bakeable up to 250°C. In the hot areas of the emitter only high-purity low vapour pressure materials like Mo, Ta, W or Al ₂ O ₃ are present.

The electron emitter is designed with 270° beam deflection, eliminating nearly all ion bombardment effects on the filament. The electromagnetic coils are manufactured from Kapton ^TM (polyimide) isolated wires and nickel-plated magnetic steel, the permanent magnets are of a high temperature rare earth material and the single-hearth crucible is manufactured from a high purity OFHC-copper block (Oxygen-Free-High-Conductivity Copper). The crucible capacity can be chosen between 40 cm³, 100 cm³ and 160 cm ³ , machined into the copper block. The cooling of the copper block is effectively accomplished by two complete turns of water bores closely around the hearth.The electron emitter is designed in a way that eliminates nearly all ion bombardment effects on the filament. This is due to the 270° beam deflection and the very sharply bent electron beam path near the exit of the asymmetrical emitter aperture. Thus it is well shielded from evaporant or charged particles ejected from the crucible (see Fig. in the right. In addition, the 270° emitter design shields the sample from a direct sight onto the hot tungsten filament further reducing the chance of sample contamination by impurities from the hot emitter area.

Application

EBV evaporators are designed for high rate evaporation of low-vapour-pressure materials, especially when high purity of the evaporant is desired. They are frequently used for evaporation of refractory metals, e.g. Mo, Nb, Ta, W, Zr, it is well suited for high-rate evaporation of Al, and of course also for semiconductors like Si and Ge. A typical application of the EBV is SiGe MBE.

For application in a silicon MBE system we provide a specially adapted set of shielding parts manufactured from high-purity single-crystalline silicon. These plates and rings cover all parts of the metallic body that are potentially subject to electron or ion bombardment and that face the substrate. Only this Si-shielding allows the growth of highest purity Si-based films with virtually no metallic contamination. We also supply high purity Si source material in superior quality, machined from wafer-grade Si-single crystals, fitting the evaporator hearth closely.

For germanium evaporation with the EBV 200-100, a crucible liner made from high purity silicon is available. Ge does not sublime, but has to be molten completely for evaporation. To prevent it from interacting with the copper hearth, this “Si-crucible” is used, leaving a capacity of about 50 cm³ for the Ge evaporant.

For metal deposition the EBV can be used “as is” for all metals that do not melt completely or that do not react with the cooled Cu-wall. For some metals, graphite- or other metal crucible-liners are used. Ask for the solution for your particular evaporant.

Technical Data

Specific Data

Example: EBV 200-40-KS-L250D195 is a standard electron beam evaporator on DN200 CF flange with 40cm³ hearth capacity, water cooling hood and integrated linear shutter, in-vacuum length 250mm and diameter 195mm.