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Electron Beam Evaporator

e--flux e-beam evaporator

e-flux electron beam evaporator with all options
e--flux Mini Electron Beam Evaporator
with 50mm rod feed, shutter, flux monitor and thermocouple option

New:
Multi-Pocket
Mini E-Beam Evaporators

familiy of mini e-beam evaporators
further information
on 2-pocket and 4-pocket versions



Animation of the 2 evaporation modes: rod and crucible evaporation:


Step 1: filament gets glowing and electrons are emitted
Step 2: high voltage is applied to the evaporation rod
Step 3: rod gets hot and starts evaporating
Step 4: due to electron collision some evaporated particles get ionised (illustrated blue)
Step 5: evaporated material exits through front aperture
Step 6: the negative biased flux electrode collects ions as means for the flux
last sequence shows the change from rod to crucible mode




E-Beam Evaporator
The e--flux Mini E-Beam Evaporator is an UHV evaporator for small and medium quantities of almost any material in the temperature range of 400K to 3100K. Evaporation is possible either directly from evaporant in rod form (2-6mm) or out of a crucible. An integrated flux monitor allows maximum deposition control. Highly efficient watercooling ensures negligible outgassing during operation. The e--flux electron beam evaporator is very compact and mounted on a CF-40 flange (2.75"OD). It can easily be retrofitted to existing UHV or MBE systems as the mounting orientation is virtually unlimited. Main applications of the e--flux Mini E-Beam Evaporator are in surface science, thin film deposition and doping. Most common evaporation materials are such as Mo, Ta, W, Au, Ag, Pt, Al, Cu, Ni, Ti, C, Si, Cr and others.

pdf version of data sheet (186kB)pdf version of e--flux Mini E-Beam Evaporator data sheet (421kB) 
 
 

Main features of the e--flux Electron Beam Evaporator:
  • Evaporation of almost every material possible
  • Dual mode operation from rod or out of crucible (e-beam heated effusion cell)
  • Simple rugged construction using only standard feedthroughs
  • Cost effective pricing
  • shutter, flux monitor, various control options, wide range of crucibles and many other options

Description:

In the evaporation zone of the e-beam evaporator a coiled tungsten filament (ground potential) is placed in the close vicinity of an electrically conducting crucible or target (high positive potential) and provides electrons which are accelerated towards the evaporant rod/crucible producing extremely high heating-power densities. The evaporation hearth is highly efficient watercooled to ensure negligible outgassing.

The construction is rugged for long term trouble free operation. Only standard feedthroughs are used even for the
rodfeed and even for the watercooling lines  to minimise downtime and enabling the user to self-service at any time. The filament can easily be replaced and can be self-made using standard Tungsten wire. 

The power supply of the e-beam evaporator is a conventional, rugged design which delivers up to 600W to allow even medium quantities of material to be deposited (>1nm/s). However, fine control of the emission current makes evaporation of very low rates (<0,01A/s) easy and reproducibly possible.


The e--flux electron beam evaporator can be tailored to almost any application using a wide range of options such as flux monitor, shutter, thermocouple, extended rod feed, many crucible materials and others.


Unique new features of the e-flux mini e-beam evaporator:

  • emission current stabilizer1
  • LED to alert rod feed2
  • direct setting of desired emission current3
  • ion trap option4
1The emission current stabilizer is a closed loop control to keep the emission
current constant automatically with rod melting down or decrease of crucible content

2An LED alerts when the evaporation rod has to be fed. Threshold can be customer set. 

3The emission current can now be set directly on a linear scale for easy reproduction.

4The ion trap option allows to deflect all charged particles out of the beam.



 
Modes of Operation:

This electron beam evaporator can be used to evaporate material in 3 ways:
  • e-beam evaporator mode: The material in rod form is directly bombarded by electrons and rises rapidly to evaporation temperature. Rod evaporation is generally preferable because it creates purest films (only evaporant is heated), no crucible employed (no crucible cost, no alloying) and evaporation from all direction possible. However, some materials such as those with high thermal conductivity and low melting points need crucible evaporation (below). Rod evaporation is suitable for refractory metals and other materials which reach high partial pressures e.g. 10-1 Torr before melting. As material is evaporated, more can be fed into the evaporation zone, using the linear motion feedthrough.
  • effusion cell mode: The material is placed in a conducting, usually refractory metal crucible which is heated by electron bombardment causing the contents to evaporate. Optional temperature control of the evaporant via a thermocouple and PID controller make this mode identical to more conventional effusion cells. Effusion cell mode is intended for insulators or other poor electrical conductors and low vapour pressure materials such as gold and aluminium which melt before reaching useful vapour pressures.
  • 'wetted wire technique': The material in form of a thin wire is winded around a rod, typically Tungsten. In a first step the material is melted onto the Tungsten rod and afterwards evaporated by electron bombardment. This method is especially suitable for materials which cannot be evaporated from rod directly and are alloying with conventional crucible materials. Typical evaporants for this technique are Platinum and Aluminium.
e-flux e-beam evaporator with all options and controller with PID temperature controller
e--flux Mini Electron Beam Evaporator (with all options) and controller


Application of the e--flux Mini Electron Beam Evaporator:

Typical applications of the e--flux electron beam evaporator are in thin film growth for surface science, MBE, doping, metalization, atomic layer deposition, optical films, oxide films and others. Materials used are e.g. Mo, Ta, W, Fe, Cr, Ti, C from rod and  Au, Ag, Al, Cu, Ni out of a crucible. Some materials like Pt have been successfully evaporated by using a 'wetted wire' technique. 
Rod evaporation is dome as standard from 2mm rods. Due to the powerful power supply evaporation from 3, 4, 5 and even 6mm is possible. As the rod evaporates it has to be from time to time fed with a linear motion drive. This can be done without breaking the vacuum, not even discontinuing the evaporation. 
Deposition rates can be achieved from sub-monolayers per minute up to several nm per second. Typical values are for refractory materials as W, Ta, Mo max 3-5nm/min and Ag, Cu, Al max 1nm/sec.

Quad Control:

The e-flux ebeam evaporator can be controlled: 
  • manually
  • manually with PI control of emission current
  • flux controlled (flux controller required) 
  • thermocouple controlled (thermocouple option and crucible mode required)

New Features of the
e--flux Mini Electron Beam Evaporator:

This e-beam evaporator / e-beam heated effusion cell provides a number of new features and advantages over previous designs:
  • The power supply is constructed using simple and rugged technology which permits high electron beam powers up to 600W standard to be generated without the use of complex failure-prone electronics.
  • The filament is a small coil consisting of several turns of tungsten wire as opposed to ‘hairpin’ and short-wire filaments. Because the filament fully surrounds the target, more uniform e-beam heating with consequently improved flux distribution can be achieved. Replacement filaments are readily fabricated from tungsten wire and easily exchanged thereby minimising operating costs. 
  • A built-in thermocouple (optional) can be used to monitor and stabilise the target temperature. The thermocouple can be used, as in any other K-Cell as part of a closed control loop comprising a PID controller and the optional control input on the power supply. 
  • Only standard feedthroughs are used to minimise servicing costs and downtime in  case of eventual failures. The watercooling lines are flange mounted (CF16,  1.33"OD) and can hence be disassembled easily. The rod feed driven by a conventional linear motion feedthrough found in most vacuum components catalogues.
  • A flux monitor is available. This is an additional electrode which intercepts the  edge of the emerging vapour beam. As the vapour leaves the crucible/rod it is partially ionised by the incoming electron beam. Some of the ions will be collected by the flux monitor electrode, generating a small positive current which is related  in magnitude to the vapour flux. Besides flux monitor a flux controller (PID) is available to keep the flux automatically constant.
  • The large electron emission surface provided by the tungsten coil filament allows  higher e-beam powers to be used at lower filament temperatures than in short  filament designs, with consequently extended filament lifetime. The filament is simple in form. Replacements may of course be purchased or be easily fabricated by the user from tungsten wire. 
  • The higher e-beam power of max. 600W allows rods with larger diameters (up to 6mm) to be evaporated or crucibles with larger volumes can be used (up to 400mm3). This in turn means that higher evaporation rates can be obtained because of the larger evaporation area and that more material may be evaporated before refilling is required. Besides the increased evaporation rates this also allows higher quality films. As the homogeneity of thin films is improved with larger distance, the disadvantage of lower deposition rates can therefore easily be compensated.
  • The design of the evaporator allows rods of up to 50mm in length to be fed into the evaporation zone. 

 

schematic of e-flux mini ebeam evaporator

schematic of e-flux mini ebeam evaporator

Schematics of e-flux Mini E-Beam Evaporator (with options)


 
    

Specification of the e-flux mini e-beam evaporator:
in-vacuum length: 190mm (without options). Special length possible on request.
max in vacuum diameter: 34mm
mounting flange: NW40CF  (2.75"OD)
bakeout temperature: max. 200C
rod feed: 25mm, optionally 50mm
crucible volume: 0,3ccm
crucible materials: Mo, Ta, W, pyrol. Graphite, BN liner, Al2O3, Quartz
deposition rate: from <0,01A/s to >2nm/s
beam divergence: 15 (12 with flux monitor)
e-beam power: max. 600W
controller: 19" rack mount, 3U high, 
230VAC/50Hz or 115VAC/60Hz or 100VAC/50Hz
options:
  • Shutter (manual and motorised)
  • flux monitor/flux controller, Deposition Controller*
  • thermocouple
  • ion trap
  • various crucibles (see above) with end caps for horizontal mount
  • motorised rod feed
  • control options (schematic)
  • others

*Deposition Controller: for many years the flux measurement of the e--flux Mini E-Beam Evaporator has been established to indicate the deposition growth rate. Besides flux monitoring a PID control was available to keep the flux/rate constant. 

As a new option for the electron beam evaporator we now a Deposition Controller is offered. This extends the flux based possibilities by features as known from quartz microbalances. The Deposition Controller can automatically run a process only by input of the desired film thickness and the evaporation rate. 

The Deposition Controller is an ideal tool for users who often want to evaporate different thicknesses or evaporation rates from known material. Parameters of up to 9 materials and processes can be stored after an initial calibration. A user friendly software is provided. Via an RS232C interface the process can be controlled and monitored.

The Deposition Controller needs the flux electrode option and it’s recommendable to have a motorised shutter for automatic end point control.

  • reproducable evaporation
  • stores up to 9 materials/process parameters
  • automatic shutter control

  • RS232C interface for control and documentation
e-flux ebeam evaporator Deposition Controlller






In the interests of continuous product development, specifications of the e--flux Mini Electron Beam Evaporator are subject to change without notice.


Quick links to other major tectra products:

Electron Beam Evaporator - 4-pocket e-beam evaporator - Plasma Source - Atomic Hydrogen SourceSputter Gun - Mini-Coater Deposition System - Sputter-Coater


   
  contact: Dipl.-Ing. Andreas Gati
tectra GmbH, Reuterweg 65, D-60323 Frankfurt, Germany
phone: Germany +49 - (0)69 - 72 00 40, 
fax: Germany +49- (0)69 - 72 04 00 
email: info@tectra.de
home: www.tectra.de

  last update: 12.11.10
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 tectra GmbH, the specialist for: microwave plasma sources, e-beam evaporators, sputter gun and atomic hydrogen source.