ion-solid interaction, scholarship enhancement talk IIT Ropar Department of Physics Material Deposition Laboratory Basanta Kumar Parida

1. Binary alloy patterning via
ion beams
Basanta Kumar Parida
04th September, 2015

2. Outline
• Course work
• Ion beam patterning
– Oblique incidence
– Normal incidence
• Binary alloy sputtering
• My work
– Material deposition lab
– Sputtering of cobalt
– Characterization of the thin films
2

3. Course work
• PHL-458 (Physics and Application of Nanomaterials) 3 credits
• PHL-603 (Advanced experimental Methods) 3 credits
• PHL-609 (Data Reduction and measurement Techniques) 3
credits
• PHL-602 (Numerical Techniques for Engineers And Scientists )
4 credits
• PHL-612 (Thin Film Science and Technology) 3 credits
• PHL-613 (Ion Beam Patterning-Principles and Applications) 3
credit
TA work
• Teaching Assistant for PHL-100
School Attended
• DST-SERB School (Ion Interactions With matters) from 2nd
March to 21st march-2015
3

4. • Ion beam sputtering -a powerful technique induce surface
nanopatterns
• Single step process for large area patterns
• Faster and cheaper compared to conventional lithographic
techniques
• Tunable process parameters
• High spatial slectivity
• Any ion beam can be put into any matter
• Nanodots and ripples
Applications
• Quantum dots in optoeletronic devices
• Nanoripples for optical interference grating
• Ripple for alignment of carbon nanotubes
• Surface adhesion for biomaterials(proteins,DNA)
Ion beam patterning
4

5. Oblique incidence
• Off-normal ion beam incidence leads to selforganised
nanoscale ripples
• Theoretical explanation (BH theory)
𝝏𝒉
𝝏𝒕
= −𝒗 𝟎 + 𝜸(𝜽)
𝝏𝒉
𝝏𝒙
+ 𝝂 𝒙
𝝏 𝟐 𝒉
𝝏𝒙 𝟐 + 𝝂 𝒚
𝝏 𝟐 𝒉
𝝏𝒚 𝟐 − 𝑲𝜵 𝟒 𝒉
𝝀 = 𝟐𝝅
𝒌 = 𝟐𝝅
𝟐𝑲
𝝂(𝒙,𝒚)
5
Ziberi, et.al J. Phys. Condens. Matter 21(2009) 224003

6. Normal incidence
• Nanodots
• Normal incidence –Sample fixed
• Oblique incidence- sample rotation
• Instability due to local curvature
• Erosion date < addition rate to surface
• Coarsening due to nonlinear terms
• Kuramoto-Shivashinsky equation
𝜕ℎ
𝜕𝑡
= −𝜈𝛻2ℎ − 𝐾𝛻4ℎ + 𝛾1 𝛻ℎ 2 + 𝛾2 𝛻2 𝛻ℎ 2 + 𝜂
6
Gago et al. Appl. Phys. Lett.89, 233101 (2006)

7. Binary alloy sputtering
• Normal incidence over a binary compound leads arrays of
nanodots
• Coupling between topography and altered composition
• For AB alloy sputtering yield and composition
𝐹𝐴 = 𝐹𝑌𝐴 𝑐 𝑠 , 𝐹𝐵 = 𝐹𝑌𝐵(1 − 𝑐 𝑠)
• For steady state bulk composition
𝑭 𝑨
𝑭 𝑩
=
𝒄 𝒃
𝟏−𝒄 𝒃
𝒄 𝒔=
𝒀 𝑩 𝒄 𝒃
𝒀 𝑨(𝟏 − 𝒄 𝒃) + 𝒀 𝑩 𝒄 𝒃
7
Shenoy et.al. Phys. Rev. Lett.98,256101(2007)

8. Binary alloy sputtering(contd…)
• Power deposited per unit area
𝑃 = 𝑃0 + 𝛼𝛻2
𝑢 + 𝛽(𝛻𝑢)2
• Mass conservation
𝜕ℎ
𝜕𝑡
= −Ω[ 𝐹𝐴 + 𝛻. 𝐽 𝐴 + (𝐹𝐵 + 𝛻. 𝐽 𝐵)]
• Rate of change of surface concentration
∆
𝜕𝑐 𝑠
𝜕𝑡
= Ω 𝑐 𝑏 − 1 𝐹𝐴 + 𝛻. 𝐽 𝐴 + 𝑐 𝑏 𝐹𝐵 + 𝛻. 𝐽 𝐵
• Erosion rate
𝑣0 = Ω(𝐹𝐴 + 𝐹𝐵)𝑃0
• Surface atomic current
𝑱𝒊 = −𝑫𝒊 𝒏 𝒔 𝜵𝑐 𝑠 𝒊
+
𝑫𝒊 𝑐 𝑠 𝒊
𝒏𝜴𝜸
𝒌 𝑩 𝑻
𝜵𝜵 𝟐
𝐡 − 𝝁𝒊 𝜵𝒉 , 𝐢 = 𝐀, 𝐁
• Instability
𝛼 𝐹𝐴 + 𝐹𝐵 > 𝜇 𝐴 + 𝜇 𝐵
8
Shipman ,Bradley Phys. Rev. B ,84,085420(2011)

9. Binary alloy sputtering(contd…)
• Aim to determine
• Lateral Mass Transport
𝑉 = 𝛺 𝐽 𝐴 + 𝐽 𝐵 𝑡0 =
𝛺
2
𝜇 𝐴 + 𝜇 𝐵 𝑠𝑖𝑛 2𝜃 𝑡0
• From SEM-EDX data or SIMS
𝐽𝑖 =
1
2
𝜇𝑖sin 2𝜃
𝐽 𝐴
𝐽 𝐴 + 𝐽 𝐵
=
𝜇 𝐴
𝜇 𝐴 + 𝜇 𝐵
9
𝝁 𝑨 & 𝝁 𝑩

10. Material deposition lab
• Installation of Magnetron Sputtering system
• Silicon and copper thin film deposition at different parameters
• Standardization at INST Chandigarh and AFM at IIT ROPAR
10

11. Sputtering of cobalt
• After a no. of failures successfully cobalt deposited
• Thickness to be reduced
• Removal of central magnet by Mild steel
11

12. Characterization of thin films
Silicon thin film
12
Cobalt thin film

13. Characterization of thin films (contd…)
SEM–EDX analysis
• Pressure=5 × 10−2
𝑇𝑜𝑟𝑟 ,50 sccm Ar+ gas flow
• Cobalt Substrate Target Distance(STD)=50 mm Power= 15 W
• Silicon STD=55 mm, Power=100 W (120,60) min deposition
13

14. Characterization of thin films (contd…)
SEM–EDX elementary mapping
14
Average Si/Co atomic
ratio of seven
spectrums
120 min deposition
~6.07
Average Si/Co atomic
ratio of seven
spectrums
60 min deposition
~18.85

15. XRD analysis
15
B4 glass substrate B3 glass substrate
B3 Si substrateB4 Si Substrate

16. AFM images
16
Si/Co-100w/10w (STD-50/40mm)120min,B8,50 sccm
Wavelength=83 nm
Periodicity=159nm

17. AFM images
17
Si/Co-100w/12w (STD-50/40mm)120min,B9,50 sccm
Wavelength=(58+72)/2=65 nm
Periodicity=(115+126)/2=120nm

18. AFM images
18
Si/Co-100w/14w (STD-50/40mm)120min,C2,50 sccm
Wavelength=(121+158)/2=139.8nm
Periodicity=180nm

19. AFM images
19
Si/Co-100w/14w(STD-50/40mm)120min,C4,40 sccm
Wavelength=110 nm
Periodicity=196 nm

20. Thanks for your kind
attention
20

21. SEM-EDX data
2 hr deposition
spectrum Si/Co At%
S-B3-1-1 22.62
S-B3-1-2 20.09
S-B3-1-3 17.23
S-B3-1-4 17.11
S-B3-1-5 17.97
S-B3-1-6 20.83
S-B3-1-7 16.16
avg 18.85
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1 hr deposition
spectrum Si/Co At%
S-B4-1-1 6.05
S-B4-1-2 5.81
S-B4-1-3 5.82
S-B4-1-4 6.52
S-B4-1-5 6.17
S-B4-1-6 5.94
S-B4-1-7 6.2
avg 6.07
Parameters
(pressure=5 × 10−2
𝑇𝑜𝑟𝑟) 50 sccm Ar gas flow
Cobalt Substrate Target Distance(STD)=50 mm Power= 15 W
Silicon STD=55 mm Power=100 W