1. Deposition of very thin films by
thermal evaporation using a heated
substrate
by
Conor Browne
Supervised by
Dr. Ger O’ Connor

2. Project Aims
• Deposit a range of Aluminium thin films of specific thickness onto a
dielectric (Glass) substrate.
• Characterise these samples using Atomic Force Microscopy (AFM),
White Light Interferometry (WLI) and Spectral Reflectivity (SR).
• Develop a high temperature substrate capability within the thermal
evaporator apparatus.
• Compare and contrast heated and non-heated samples using the
results gathered from the AFM, WLI and SR.
Applications:
Mirrors Space blankets Spaceship insulation
Slide 2

3. Experimental procedure
Glass
Glass
Deposition
Glass
Heated
Non-heated
Al
Glass
Aluminium
Al
Glass
Al
Glass
Al
Glass
Characterization
AFM Reflectivity WLI
Slide 3

4. K975x Thermal Evaporator set-up Standard method:
• Place mass of Aluminium in the crucible,
place glass slide into the slide holder.
• Begin the vacuum process.
• Increase the current to turn Al into a vapour.
• Upon reaching desired thickness turn down
current.
• Purge the chamber.
0
3
6
9
12
15
18
21
24
27
30
0 10 20 30 40 50 60
DepositedAl
thickness(nm)
Time (s)
Average Deposition Rates
12 Amps
Averaged
11 Amps
Averaged
10 Amps
Averaged
9 Amps
Averaged
Slide 4
Experimental procedure

5. Glass slide heater
Heater method:
• Ramp up the current to 35A over
100s (3-4A every 10s).
• Heat slide for 300s at this current.
• Ramp current down over 100s.
• Begin deposition process.
Improvements made to the standard method:
• Use of a constant mass of Aluminium.
• Steady increase in current supply (One Amp
increase every 10 seconds).
• Cleaning glass slides with Isoclene before
use.
• Handled slides with latex gloves.
• Evaporating off any residual Aluminium that
built up on the crucible.
Thin film sample of
thickness 25.6 ±3.25 nm
Slide 5
Experimental procedure

6. Results: Reflectance and White Light Interferometer
0.05
0.09
0.13
0.17
0.21
0.25
0.29
0.33
0.37
0.41
0.45
350 400 450 500 550 600 650 700 750 800 850 900 950 1000
Reflectance(%)
Wavelength (nm)
Average Reflectance profiles for Aluminium thin films
Non-Heated
Reflectance
Heated
Reflectance
Glass slide
Reflectance
Heated roughness:
0.0013 ± 0.0003 (µm)
Non-heated roughness:
0.0087 ± 0.0007 (µm)
Slide 6

7. Results: Atomic Force Microscope I
Non-heated sample grain size average:
0.0239 ± 0.0004 µm²
Heated sample grain size average:
0.0811 ± 0.0074 µm²
Slide 7

8. Results: Atomic Force Microscope II
0
2
4
6
8
10
12
14
16
18
20
22
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Height(nm)
Width of scan (µm)
Heated average side profile (AFM scan)
0
2
4
6
8
10
12
14
16
18
20
22
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Height(nm)
Width of scan (µm)
Non-heated average side profile (AFM scan)
Non-heated sample roughness average: 5.068 ± 0.378 nm
Heated sample roughness average: 2.958 ± 0.259 nm Slide 8

9. Conclusion
• Roughness and grain size have all been improved upon heating
of the substrate. Reflectivity has decreased due to the grain size.
• Reduction of 41.6% in the roughness of heated samples when
compared to non-heated samples from the results of the AFM.
• WLI measurements of both sets of samples verified a reduction in
the roughness of the heated samples.
• The grain sizes of the heated samples were found to be roughly
3.5 times larger than the grain sizes observed in non-heated
samples from the results of the AFM grain size analysis.
Slide 9

10. Acknowledgements
Thank you for your time.
I would like to thank:
Dr. Ger O’ Connor
James Nallen
Conor Mc Brierty
Clare Mc Daniel
Pinaki Das Gupta
Slide 10