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| We can deposit Carbon (C) by DC sputtering in Sputter-System (Lesker). A 2-inch target from gun 1 (DC) is used in the process. Since the material is known to possess cross-contamination issues it was decided to cover all other guns with the protection foil.
| | == Deposition of Carbon == |
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| The fabrication and characterization described below were conducted in <b>2022 by Patama Pholprasit and Evgeniy Shkondin, DTU Nanolab</b>. The prepared samples were investigated by the X-ray Reflectivity (XRR), Spectroscopi Ellipsometry (SE), Photo Electron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Graizing Incident Diffraction (GiXRD) methods. The focus of the study was the deposition conditions.
| | Carbon can be deposited by DC-sputtering method. So far the process has been tested only using Sputter-System (Lesker): |
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| | | *[[/Deposition of C in Sputter-System Lesker|Deposition of Carbon in Sputter-System (Lesker)]] |
| Recipe:
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| * Power: <b>200 W</b> | |
| * Pressure: <b>3 mTorr</b>
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| * Power rump: <b>0.3 W/s</b>
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| * Deposition mode: <b>DC</b> (Src1)
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| * Deposition time: <b>10, 20, 30 min and 6000s for GiXRD measurement)</b>
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| * Substrate: <b>4-inch Si</b> and a variety of others (glass, silicon nitride) to study adhesion and conductivity.
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| | |
| ==Deposition Rate==
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| Deposition rate for C at 200W power (DC) and 3 mTorr presssure is <b>0.01 nm/s</b>
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| <gallery caption="Carbon deposition rate." widths="500px" heights="400px" perrow="1">
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| image:eves_deposition_rate_Carbon_200W_3mTorr_20min_20221018.png| Carbon thin films deposited on Si wafer and measured by XRR method. 10, 20 and 30 min of deposition time using 200W, 3 mTorr, Src1 DC.
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| </gallery>
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| | |
| ==X-ray Reflectivity==
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| X-ray analysis (XRR) of samples (deposited at 10min, 20 min, and 30 min) have been performed to investigate the thicknesses, roughness, and density profiles.
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| The scans has been obtained using Rigaku XRD SmartLab equipment. The voltage and current settings for the Cu X-ray tube were standard 40kV and 30mA. The incident optics contained a IPS (incident parallel slit) adaptor with 5 ° Soller slit. Other slits: IS=0.03mm RS1=0.03mm and RS2=0.075mm. Step size: 0.01 and measurement time - 5s for each point. Fitting procesure was performed using commercial GlobalFit software assuming the model based on Si or SiO<sub>2</sub> substrates with native oxide/interlayer followed by the deposited C film with thin oxides and moisture surfaces. The results are summarized in a tables below.
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| ====Fitting resilts for Carbon films====
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| <gallery caption="Carbon thickness measurements. X-ray reflectivity analysis." widths="450px" heights="400px" perrow="3">
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| image:eves_XRR_Carbon_200W_3mTorr_10min_20221018.png| <b>10 min</b> deposition from Src1.
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| image:eves_XRR_Carbon_200W_3mTorr_20min_20221018.png| <b>20 min</b> deposition from Src1.
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| image:eves_XRR_Carbon_200W_3mTorr_30min_20221018.png| <b>30 min</b> deposition from Src1.
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| </gallery>
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| {| border="2" cellspacing="2" cellpadding="3" colspan="13"
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| |bgcolor="#eed5d2" |'''XRR results for Carbon layers'''
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| |-
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| {| {{table}}
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| | align="center" |
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| {| border="2" cellspacing="2" cellpadding="3" align="center" style="width:1500px"
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| |-
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| !colspan="1" style="background:silver; color:black;" align="center" |
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| |colspan="3" style="background:silver; color:black;" align="center" |<b>Top layer (moisture)</b>
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| |colspan="3" style="background:silver; color:black;" align="center" |<b>Main layer</b>
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| |colspan="3" style="background:silver; color:black;" align="center" |<b>Si native oxide</b>
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| |colspan="3" style="background:silver; color:black;" align="center" |<b>Si substrate</b>
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| | |
| |-
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| !style="background:WhiteSmoke; color:black;" align="center" |Deposition time
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Moisture thickness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Moisture density (g/cm<sup>3</sup>)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Moisture roughness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Carbon thickness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Carbon density (g/cm<sup>3</sup>)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Carbon roughness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>SiO<sub>2</sub> thickness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>SiO<sub>2</sub> density (g/cm<sup>3</sup>)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>SiO<sub>2</sub> roughness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Si thickness (nm)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Si density (g/cm<sup>3</sup>)</b>
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| |style="background:WhiteSmoke; color:black;" align="center" |<b>Si roughness (nm)</b>
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| |-
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| |<b>10 min</b>
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| |1.55
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| |0.428
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| |1.33
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| |<p style="color:red;"><b>6.33</b></p>
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| |<p style="color:red;"><b>2.00</b></p>
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| |<p style="color:red;"><b>0.50</b></p>
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| |0.32
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| |2.12
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| |0.00
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| |<math>\infty</math>
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| |2.33
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| |0.00
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| |-
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| |<b>20 min</b>
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| |1.16
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| |0.43
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| |0.88
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| |<p style="color:red;"><b>12.34</b></p>
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| |<p style="color:red;"><b>2.00</b></p>
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| |<p style="color:red;"><b>0.67</b></p>
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| |0.17
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| |2.19
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| |0.00
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| |<math>\infty</math>
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| |2.33
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| |0.00
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| |-
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| |<b>30 min</b>
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| |1.20
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| |0.40
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| |0.85
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| |<p style="color:red;"><b>18.30</b></p>
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| |<p style="color:red;"><b>2.00</b></p>
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| |<p style="color:red;"><b>0.81</b></p>
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| |0.13
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| |1.99
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| |0.00
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| |<math>\infty</math>
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| |2.33
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| |0.00
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| | |
| |-
| |
| |}
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| |-
| |
| |}
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| |}
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| <br clear="all" />
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| | |
| {| border="2" cellspacing="2" cellpadding="5" align="center"
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| | |
| |-
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| !colspan="14" border="none" style="background:silver; color:black;" align="center"| Fitting parameters
| |
| |-
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| |style="background:WhiteSmoke; color:black" rowspan="2"|<b>Sample</b>
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| |colspan="2" border="none" style="background:WhiteSmoke; color:black"|<b>Moisture</b>
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| |colspan="2" border="none" style="background:WhiteSmoke; color:black"|<b>Carbon</b>
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| |colspan="2" border="none" style="background:WhiteSmoke; color:black"|<b>Si native oxide</b>
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| |colspan="2" border="none" style="background:WhiteSmoke; color:black"|<b>Si substrate</b>
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| |colspan="5" border="none" style="background:WhiteSmoke; color:black"|<b>Fitting parameters</b>
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| | |
| |-
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| |style="background:WhiteSmoke; color:black"|<b>Delta</b>
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| |style="background:WhiteSmoke; color:black"|<b>Beta</b>
| |
| |style="background:WhiteSmoke; color:black"|<b>Delta</b>
| |
| |style="background:WhiteSmoke; color:black"|<b>Beta</b>
| |
| |style="background:WhiteSmoke; color:black"|<b>Delta</b>
| |
| |style="background:WhiteSmoke; color:black"|<b>Beta</b>
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| |style="background:WhiteSmoke; color:black"|<b>Delta</b>
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| |style="background:WhiteSmoke; color:black"|<b>Beta</b>
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| |style="background:WhiteSmoke; color:black"|<b>Intensity</b>
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| |style="background:WhiteSmoke; color:black"|<b>Background</b>
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| |style="background:WhiteSmoke; color:black"|<b>Fitting area (<math>2\Theta</math>)</b>
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| |style="background:WhiteSmoke; color:black"|<b>R</b>
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| |style="background:WhiteSmoke; color:black"|<b><math>\Chi^2</math></b>
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| | |
| |-
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| |<b>10 min</b>
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| | 1.3932E-6
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| | 3.2352E-8
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| | 6.4587E-6
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| | 9.7010E-9
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| | 6.9134E-6
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| | 1.6054E-7
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| | 7.5860E-6
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| | 1.7616E-7
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| | 1.14309
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| | 7.02370E-8
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| | 0.2666 - 5.000
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| | 0.02092
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| | 0.01081
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| | |
| |-
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| |<b>20 min</b>
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| | 1.4031E-6
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| | 3.2581E-8
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| | 6.4279E-6
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| | 9.6547E-9
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| | 7.1423E-6
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| | 1.6585E-7
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| | 7.5860E-6
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| | 1.7616E-7
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| | 0.93079
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| | 1.96097E-8
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| | 0.2666 - 4.000
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| | 0.01987
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| | 0.00899
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| |-
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| |<b>30 min</b>
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| | 1.2905E-6
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| | 2.9968E-8
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| | 6.4412E-6
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| | 9.6747E-9
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| | 6.4832E-6
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| | 1.5055E-7
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| | 7.5860E-6
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| | 1.7616E-7
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| | 0.88610
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| | 3.11353E-8
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| | 0.3143 - 4.000
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| | 0.02722
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| | 0.01877
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| | |
| |}
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| <br>
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| <!-- -->
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| <br clear="all" />
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| <br clear="all" />
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| ==Graizing Incident Diffraction (GiXRD)==
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| Graizing Incident Diffraction (GiXRD) of 60 nm C sample (deposited at 6000s, 200W, 3 mTprr, DC, Src1) has been performed to investigate the phase profile. The analysis revealed the amorphous film.
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| The scan has been obtained using Rigaku XRD SmartLab equipment. The voltage and current settings for the Cu X-ray tube were standard 40kV and 30mA. The incident optics contained a IPS (incident parallel slit) adaptor with 5 ° Soller slit.
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| Other conditions: IS=1 mm, ω=2 ° PSA 0.5 ° RS1=RS2=open, Lenght-limiting slit=15mm, Speed: 0.5 ° /min. Angle range: 20-90 2θ.
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| <gallery caption="GiXRD analysis." widths="1500px" heights="400px" perrow="2">
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| image:eves_GiXRD_Carbon_200W_3mTorr_6000s_20221018.png|Amorphous film. No diffraction peaks.
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| </gallery>
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| ==X-ray Photoelectron Spectroscopy==
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| Oxygen is almost non existing in the film (around or less than 1 at.%). The signal eventually rises during the depth profiling. It comes from the Carbon-Silicon interface (native oxide). No other contaminants have been found.
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| <gallery caption="Carbon XPS analysis." widths="450px" heights="400px" perrow="2">
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| image:eves_XPS_concentration_Carbon_200W_3mTorr_20min_20221018.png| Atomic concentartion as a fnction of depth. Etching parameters: 1000eV, low current, 10s@50 levels.
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| image:eves_XPS_survey_Carbon_200W_3mTorr_20min_20221018.png| Survey spectrum after 10s Ar<sup>+</sup> etch (1000eV, low current).
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| </gallery>
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| <gallery caption="Carbon XPS measurements. High-Resolution profiles." widths="450px" heights="400px" perrow="3">
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| image:eves_XPS_C1s_Carbon_200W_3mTorr_20min_20221018.png| C 1s.
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| image:eves_XPS_O1s_Carbon_200W_3mTorr_20min_20221018.png| O 1s.
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| image:eves_XPS_Si2p_Carbon_200W_3mTorr_20min_20221018.png| Si 2p.
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| </gallery>
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| <gallery caption="Carbon XPS measurements. High-Resolution profiles in 2D" widths="1400px" heights="400px" perrow="1">
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| image:eves_XPS_2D_20min_C_200W_3mTorr_Src1_DC_2D_20221219.png| 2D image of XPS depth profiles.
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| </gallery>
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| ==Scanning Electron Microscopy==
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| <gallery caption="Carbon deposition. SEM inspection." widths="450px" heights="400px" perrow="1">
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| image:eves_SEM_Carbon_200W_3mTorr_20min_20221018.png| <b>C</b> deposited on high aspect ratio silicon structure (trenches) with <b>200W</b> power and <b>3 mTorr</b>, 20min. Cross-sectional tilted view.
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| </gallery>
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| ==Spectroscopic Ellipsometry==
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| Results have been obtained for Si wafers with native oxide, based on ellipsometry study. The Bspline model has been used for analysis.
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| <gallery caption="Optical functions based on Spectroscopic Ellipsometry method." widths="450px" heights="400px" perrow="2">
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| image:eves_SE_refr_index_Carbon_200W_3mTorr_20min_20221018.png| Refractive index of carbon deposited at 30 min, 200W, 3 mTorr, DC, Src1.
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| image:eves_SE_abs_coeff_Carbon_200W_3mTorr_20min_20221018.png| Absorption coefficient of carbon deposited at 30 min, 200W, 3 mTorr, DC, Src1.
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| </gallery>
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| ==Conductivity==
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| Sheet resistance has been performed using Four point probe – Jandel. The deposited carbon film (6nm at 600s, 200W, 3 mTorr) on top of a microscope glass slide showed <b>178-223 MOhm/sq</b> range.
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| ==Deposition Recordings==
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| <gallery caption="Deposition recordings (30min) Src1 DC." widths="350px" heights="350px" perrow="4">
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| image:eves_recordings_flow_Carbon_200W_3mTorr_20min_20221018.png| <b>Ar flow recording</b>. Thin layer (1800s deposition time).
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| image:eves_recordings_pressure_Carbon_200W_3mTorr_20min_20221018.png| <b>Pressure recording</b>. Thin layer (1800s deposition time).
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| image:eves_recordings_power_Carbon_200W_3mTorr_20min_20221018.png| <b>Power recording</b>. Thin layer (1800s deposition time).
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| image:eves_recordings_voltage_Carbon_200W_3mTorr_20min_20221018.png| <b>Voltage recording</b>. Thin layer (1800s deposition time).
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| </gallery>
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