OM-SC7610
Operation
Issue 1
23
SC7610 Sputter Coater
(e)
Close down the system, as follows
:
(i)
Close the
LEAK
valve (turn fully clockwise).
(ii)
Operate the
START PUMP
button, the indicator will extinguish and the rotary pump will
be turned OFF.
(iii)
Open
VENT
valve to admit gas to the vacuum chamber. When sufficient gas has
entered the chamber, positive pressure will ‘pop’ the top plate open
(iv) Close the
VENT
valve.
6.2
Coating Process
A metal film of uniform thickness between 50 and 300 Å Is generally used for SEM investigations.
Care must be taken to ensure the vacuum chamber is kept clean and free from contamination.
Contamination which can arise from the out-gassing of specimens, adhesives (especially
Chlorohydrocarbon based solvents) and rubber gaskets will adversely affect the quality and rate of
sputtering.
A measure of thickness can be obtained using the following equation:
d = KIVt
d
The coating thickness in Angstrom units.
K
An experimentally determined constant based on:
The metal being sputtered,
The gas being used,
45 mm (approx.) target to sample distance.
For gold used with argon, K = 0.17 approx.
For gold used with air, K = 0.07 approx.
I
is plasma current , in mA.
V
is the applied voltage, in kV, (1 kV).
t
is the sputtering time, in seconds.
For a typical sputtering, using gold in argon with a plasma current of 18 mA for 120 seconds:
d = KIVt = 0.17 x 18 x 1 x 120
= 367 Å (approx. 3 Å / second)
The uniformity of the coating thickness within the area of the specimen holder is better than 10%.
6.3
Coating Specimens
(a)
Mount specimens
(i)
Prepare specimens on stubs, using an approved method.
(ii)
Lift the glass cylinder (with top plate fitted) clear of the cabinet and place aside on a
clean surface.
(iii)
Adjust the height of the sample stage. Whilst the most suitable height for a particular
application can best be established empirically, 35mm between top of the sample and
the target provides a satisfactory general purpose setting.
(iv)
Mount the stubs (with attached samples) on the sample stage.
(v)
Position the glass cylinder and top plate on the sputter coater, to enclose the sample.