ntroduction
A set of substrates have been coated by the Colorado State University Fort Collins group, with ~500 nm tantala and various ion assist beam parameters. Here's a table summarizing the depositions parameter, by Le Yang
|
substrate
|
main ion source voltage / V
|
main ion source current / mA
|
main ion source Ar flow / sccm
|
target oxygen flow / sccm
|
assist ion source voltage / V
|
assist ion source current / mA
|
assist ion source gas/sccm
|
thickness / nm
|
abs
/ ppm
|
notes
|
|
Ar
|
O2
|
| s1600525 |
1250 |
600 |
18 |
49 |
100 |
100 |
12.5 |
0 |
480 |
|
|
|
s1600535
|
1250
|
600
|
18
|
49
|
100
|
100
|
12.5
|
0
|
541
|
7.2
|
|
|
s1600536
|
1250
|
600
|
18
|
49
|
100
|
100
|
3.5
|
9
|
532
|
20.2
|
|
|
s1600537
|
1250
|
600
|
18
|
49
|
100
|
100
|
6.5
|
6
|
534
|
|
damaged
by
holder
|
|
s1600538
|
1250
|
600
|
18
|
49
|
100
|
100
|
6.5
|
6
|
524
|
|
scratch
|
|
s1600547
|
1250
|
600
|
18
|
49
|
100
|
100
|
6.5
|
6
|
528
|
15.4
|
|
|
s1600532
|
1250
|
600
|
18
|
49
|
200
|
100
|
12.5
|
0
|
518
|
17.8
|
|
|
s1600539
|
1250
|
600
|
18
|
49
|
200
|
100
|
3.5
|
9
|
541
|
17.7
|
|
|
s1600533
|
1250
|
600
|
18
|
49
|
200
|
100
|
6.5
|
6
|
539
|
11.6
|
|
|
s1600530
|
1250
|
600
|
18
|
49
|
100
|
200
|
12.5
|
0
|
537
|
10.3
|
|
|
s1600550
|
1250
|
600
|
18
|
49
|
100
|
200
|
3.5
|
9
|
519
|
19.9
|
|
|
s1600548
|
1250
|
600
|
18
|
49
|
100
|
200
|
6.5
|
6
|
532
|
17.2
|
|
Coating losses before annealing
The plot below shows the measured loss angle for all modes of all samples, before annealing. The error bars for the datapoints are from the 95% confidence intervals computed from 8 measurements each. The red line is the average value over frequencies, and the shaded red area gives the 95% confidence interval of the mean value. The loss angle seems reasonably indipendent of frequency.
The following pot then shows the averaged loss angle as a function of the serial number, for reference
There are three main parameters that are changed in the deposition: the assist beam voltage, the assist beam current and the content of oxygen in the assist beam. The plots below show the losses as a function of those parameters. The x axis changes in each of the four panels, and for each plot, the color code is linked to one of the process variables:
  
Conclusions
Quoting Le Yang and Carmen Menoni
- under certain conditions as oxygen flow increase and Ar flow decrease, the loss angle becomes worse
- with existence of oxygen ions the loss is mitigated by increase of beam voltage
- relatively small particle size of oxygen compared with argon the caused the less effective interaction between assist ions and coating adatoms on the surface
- with increase of ion dose, the mechanical loss drops
|