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Chapter

1

Introduction

1.1 Overview

The   EBE-1   uses  electron   bombardment  to   produce   intense   localised   heating.   Rods 

and/or small crucibles may be heated in this way. They are placed inside a ring filament 
at ground potential. Electrons from the incandescent filament are attracted towards 

the rod or crucible, which is held at high positive potential and must be electrically con-
ducting. By accelerating the electrons to 2 kV and allowing the emission of up to 200 

mA of electron current, a total heating power of up to 400 W may be delivered into a 
very small area creating extremely high power densities and allowing temperatures in 

excess of 3500 

o

C to be reached. Material evaporated in rod form may be fed continu-

ously into the e-beam heating zone as it evaporates away. Lengths of up to 50 mm may 

be evaporated.

1.2 Rods and Crucibles

Materials which are electrically conducting and develop a useful vapour pressure before 
melting may be evaporated directly from their rod form. Perfect examples of such ma-

terials are chromium and carbon which both sublime as the temperature is increased, as 
well as many refractory metals such as molybdenum and tungsten which develop use-

fully high vapour pressures before melting.
Materials which melt before reaching high enough evaporation temperatures will ball-

up on the end of the rod before eventually dripping off the rod.  This balling effect can 
be controlled in some borderline materials such as silicon where use of a 4 mm or 5 mm 

EBE-1

1

Summary of Contents for EBE-1

Page 1: ...EBE 1 Electron Beam Evaporator 1 11...

Page 2: ...r manual for the Electron Beam Evaporator EBE 1 Version 1 11 dated at 18 March 2008 SPECS order number for this manual 78 000 155 EBE 1 SPECS GmbH Surface Analysis and Computer Technology Voltastrasse...

Page 3: ...3 Installation 5 3 1 Connections 5 3 2 Linear Motion Thimble 6 3 3 Mounting rods and crucibles 6 3 4 Conditioning the filament 7 3 5 HV conditioning 8 3 6 Setting up rod position 8 4 Operation 9 4 1...

Page 4: ...ntrol of the PID Controller 14 4 4 2 Setting the Maximum and Minimum Output 15 4 4 3 Setting up Auto Control 16 4 4 4 PID and Controller Parameters 17 4 4 5 Safe operation tips 17 5 Maintenance 19 5 1...

Page 5: ...00 o C to be reached Material evaporated in rod form may be fed continu ously into the e beam heating zone as it evaporates away Lengths of up to 50 mm may be evaporated 1 2 Rods and Crucibles Materia...

Page 6: ...ts associated power supplies contain lethally high voltages and should not be used by anybody except trained qualified personnel Improper use may lead to serious injury or death Particularly hazardous...

Page 7: ...suit that rod or crucible in use see later section on fil aments The resistance from the centre pin of the MHV feedthrough on the thimble to ground should be 20 M The resistance between the centre pin...

Page 8: ...Inspection 4 EBE 1...

Page 9: ...e through the press fit lid seal 3 1 Connections The cable comprises a low voltage high current cable for the filament and a high voltage low current cable for the HV The HV cable is fitted with MHV c...

Page 10: ...d excessive force be used The total thimble mo tion is 50 mm When fully compressed the ends of the knurled grip are no more than half way across the heads of the M3 countersunk mounting screws The ful...

Page 11: ...tage should be off Raise the current to say 4 A Allow it to stay at this current for a few seconds then turn the filament current off Repeat this procedure increasing the current by 1 A each time When...

Page 12: ...ode which would otherwise damage the flux electronics Before evaporating with a rod for the first time drive the rod into its fully forward pos ition using the thimble drive The rod will now stick rig...

Page 13: ...ical achievable evaporation rate which will be reached when the local vapour pressure around the tip of the rod or mouth of the crucible is high enough for the HV to generate an arc through the vapour...

Page 14: ...ysical phenomena of the evapora tion and lead to runaway effects which are not seen until too late Electronically stabil ised evaporation is best achieved by regulating the filament current from a dep...

Page 15: ...ould be capable of making rate measurements and not just ac cumulated thickness and should have a resolution of 0 1 nm s or better It is only really by monitoring the actual deposition rates that the...

Page 16: ...om thick rods to just a minute or so for high rates from thin rods 4 2 3 Ending evaporation Turn off the filament and then the HV 4 3 Evaporation from crucibles The crucible should be positioned fully...

Page 17: ...rates so that sufficient depos ition time is available before the rod is used up and needs to be driven forward again The flux controller converts the small current signal intercepted by the flux elec...

Page 18: ...good control it should now be apparent that the measured flux is directly related to the e beam power Reducing the filament current and thereby the emission current should cause a clear decrease in t...

Page 19: ...value The arrow keys can now be used to directly control the PID controller output Set the Man Auto switch to Auto 4 4 2 Setting the Maximum and Minimum Output Set the Set point on the PID controller...

Page 20: ...urrent begins to be seen this can be seen on the HV supply and on the main power supply Carefully and slowly allow the material to come to thermal equilibrium Adjust the fila ment current using the PI...

Page 21: ...his can also be achieved by adjusting the potentiometer nearest to the black heatsink on the filament triac board in the power supply so that at full PID controller output the filament current is only...

Page 22: ...Operation 18 EBE 1...

Page 23: ...nt holder 3 Lift up the Macor filament holder taking care to feed the filament out through the slot in the copper block and at the same time pulling the copper current leads out of the end of the fila...

Page 24: ...short length of tungsten wire around the shank the non threaded portion of an M8 bolt Using stout tweezers or needlenose pliers take one loop of the wire and bend the ends back near to where they cros...

Page 25: ...tandard Also ac cepts crucibles Crucible volume 0 25 cc Crucible materials Mo Ta W pyrolytic graphite PG vitreous carbon VC Table 1 Physical specifications 6 2 Beam Deposition Rate Measured at 100 mm...

Page 26: ...utter motorisation Contains a DC gear motor drive 2 Crucibles Mini crucibles with 0 25 cc capacity in a variety of ma terials including Mo Ta W pyrolytic graphite PG vitreous carbon VC Matching lids a...

Page 27: ...gs EBE 1 23 Figure 3 Evaporator overview and dimensions 50mm thimble HV connector Water in out Rotary drive 2 75 NW35CF Mounting flange Flux monitor Shutter 200 203 e e e e Filament Evaporated materia...

Page 28: ...Drawings 24 EBE 1 Figure 4 Evaporator details...

Page 29: ...Chapter LF List of Figures Figure 1 Front panel flux controller 13 Figure 2 Filament dimensions 20 Figure 3 Evaporator overview and dimensions 23 Figure 4 Evaporator details 24 EBE 1 I...

Page 30: ...List of Figures II EBE 1...

Page 31: ...Chapter LT List of Tables Table 1 Physical specifications 21 Table 2 Beam specifications 21 Table 3 Power supply specifications 22 Table 4 Options 22 EBE 1 III...

Page 32: ...List of Tables IV EBE 1...

Page 33: ...examples 1 F feedthrough 3 5 filament 3 5 7p 19p filament current 7p 10 filaments 3 flux 14 flux controller 5 13p flux electrode 3 G gases 14 ground 3 I IEC plug 5 L limit 7 M Mains 5 MHV feedthrough...

Page 34: ...s liquids evaporation products sputtering products Yes No toxic substances corrosive substances microbiological substances incl sample material radioactive substances incl sample material ionising par...

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