|
OMICRON Product Line
UHV Evaporator EFM3, EFM4
UHV Triple Evaporator EFM3T
In the UHV evaporators EFM 3/4/3T (Evaporator with integral Flux Monitor) the evaporant is
either evaporated from a bar, from a rod or from a crucible. This is achieved by electron bombardment heating. The bombarding electron beam induces a temperature rise of the
evaporant, causing evaporation.
The crucible-free evaporation is characterised by an ultimate degree of cleanliness with only
slight increases of background pressure. From appropriate crucibles (see appendix A) low melting point, low vapour pressure or reactive materials can be evaporated. The instrument is
designed for high precision sub-mono-layer up to multi-layer deposition of a wide variety of evaporants including highly refractory materials.
A key feature of the EFM is the integrated flux monitor. Once calibrated the flux monitor
replaces the necessity of a quartz thickness monitor by continuously monitoring the evaporation rate. Flux is measured directly, which allows a much more precise rate adjustment
and much faster rate control than an indirect, i.e. temperature measurement by a thermocouple.
The beam exit column contains an ion collector which serves as a flux monitor. At a given electron emission current (IEM) and e-beam energy the ion flux measured there is
directly proportional to the flux of evaporated atoms. The ion flux is displayed on the left indicator of the electronics unit. The flux monitor also operates with the shutter closed thus
allowing to pre-set the evaporation rate.
The EFM comes with a shutter at its outlet which can be opened and closed by a rotary drive.
This allows precise flux adjustment prior to exposure, and exact control of the evaporation time. As an option, the shutter can be motor operated under computer remote control together with
the power supply EVC300.
The evaporation cell is contained in a water-cooled copper cylinder (cooling shroud). This, and
the fact that just a restricted region of the evaporant is heated facilitates to keep the background pressure during evaporation below 10-10 mbar. But this also depends on the target
material and on the pumping speed of the vacuum system. Some evaporants and crucibles contain huge amounts of gas that are deliberated on heating.
Triple evaporator EFM 3T
The triple evaporator EFM 3T features three completely separated evaporation cells on one
CF 35 flange each one similar to a single EFM 3. Each cell has an independent electron bombardment heater. It can be used for simultaneous or subsequent evaporation of up to three
different materials and is therefore ideally suited to grow binary and tertiary compounds or multilayers.
The evaporation shows no material crosstalk between the three cells. Each cell has its integral
flux monitor so that the flux can be measured independently and pre-set before opening the shutter. With the shutter mechanism each cell can be opened separately as well as various
combinations of the cells.
Specifications EFM3/4
|
beam spot diameter at the sample
|
EFM 3 : 4 to 15 mm,
EFM 4 : 6 to 40, depending on distance and exit
|
|
beam divergence:
|
EFM 3 : ± 2°, ± 2.2° or ± 2.4°, dependent on exit tube mounted.
With the EFM 3 come three
exchangeable exit tubes of 4, 6 and 7.4 mm I.D.
EFM 4 : ± 2.2°, ± 3.6°, ± 5.1° or ± 6.9°, depending on exit aperture.
With the EFM 4 come four
exchangeable exit apertures of 6, 10, 14 and 19 mm I.D..
|
|
distance flange to sample
|
220 - 270 mm (other length on request)
|
|
distance tip of evaporant to sample:
|
100-150 mm typically
|
|
distance end of EFM to the sample:
|
10-60 mm
|
|
e-beam energy:
|
about 0-1000 eV, (600-800 eV typically),
Imax= 300 mA, Pmax= 300 W with EVC300
|
|
maximum bakeout temperature :
|
250°C
|
|
maximum crucible load:
|
see list in the appendix E1
|
|
cooling water flow:
|
> 0.5 l/min at T about 30 °C, maximum pressure = 6 bar
|
|
temperature range with
rod evaporation:
|
300° up to 3300°C, depends on size of evaporant (heat loss)
|
|
temperature range with Ta- or Mo-crucible:
|
300° - 2000°C
|
|
temperature range with Knudsen crucible (stainless steel):
|
160°C - 800° C
|
|
rod diameter:
|
0.5 -3 mm, depending on maximum temperature to be reached, standard Mo clamp accepts 0.5 to 1.5 mm
diameter.
|
|
Filament current:
|
typically 1.8 - 2.2 A, 2.5 A maximum
|
|
Weight of evaporator:
|
2.2 kg
|
|
Specifications EFM 3T
|
flange to sample distance:
|
10’’ = 254mm
|
|
beam spot diameter at the sample
|
15mm with 5mm I.D. exit aperture
11mm with 4mm I.D. exit aperture
8.5mm with 3mm I.D. exit aperture
|
|
beam divergence:
|
± 2°, ± 2.2° or ± 2.4°, dependent on exit apertures mounted. With the EFM 3T come three
exchangeable exit apertures of 3,4 and 5 mm I.D..
|
|
selectable evaporation cells
|
all combinations except simultaneous evaporation out of cell 2 and cell 3 (see fig.2.7)
|
|
distance from the end of EFM to the sample:
|
94mm
|
|
e-beam energy:
|
about 0-1000 eV, (600 - 800 eV typically),
Imax= 105 mA, Pges £ 300 W
|
|
maximum bakeout temperature :
|
250°C
|
|
maximum crucible load:
|
see list in the appendix E1
|
|
maximum crucible diameter
|
8mm o.d.
|
|
cooling water flow:
|
= 0.5 l/min at T about 30 °C, maximum pressure = 6 bar
|
|
temperature range with
rod evaporation:
|
300° up to 3300°C, depends on size of evaporant (heat loss)
|
|
temperature range with Ta- or Mo-crucible:
|
300° - 2000°C
|
|
temperature range with
Knudsen crucible (stainless steel):
|
160°C - 800° C
|
|
rod diameter:
|
0.5 -3 mm, depending on maximum temperature to be reached, standard Mo clamp accepts 0.5 to 1.5 mm
diameter.
|
|
IFIL:
|
typically 2.0 - 2.4 A, 2.7 A maximum
|
|
Weight of evaporator:
|
2.5 kg
|
|
This product is part of the OMICRON Product Line
|
