Plasma Diagnostics for the Deposition of Nanomaterials
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Transcript of Plasma Diagnostics for the Deposition of Nanomaterials
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Plasma Diagnostics for the Deposition of Nanomaterials
Jay MehtaUndergraduate Student, University of Arkansas, Fayetteville, Arkansas 72701, USA
Faculty Mentor: Dr. Matthew H. GordonAssociate Professor of Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas 72701,
USA
Ph.D. Graduate Student Mentor: Sam MensahGraduate Student, University of Arkansas, Fayetteville, Arkansas 72701, USA
REU: Mechanical EngineeringUniversity of Arkansas
July 20, 2009
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Why alpha alumina?
• Many desirable properties:» high melting temperature (2053 °C)» Considered best anti—oxidation coating at high temps» corrosion resistance» chemical inertness» High mechanical strength and hardness (24GPa)» Great insulating properties
• Applications:» Optical coatings» Thermal coatings» Dielectric films» Cutting tools » Biomedical implants
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Goals
• Long term: » Connecting spectroscopy results with film quality» Better understanding of alpha alumina
• Short term:» Using OES to observe and study plasma in deposition chamber under varying
conditions
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
What is OES?
• Optical Emission Spectroscopy» Spectrometer captures data from captured photons» Produces a spectrograph» Relative intensity of peaks can be used to determine ion density
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Equipment Used
• ICM10» Midfrequency inverted cylinder AC magnetron sputtering system» Used for Physical Vapor Deposition» For our case depositing Alumina (Al2O3)
• Target: Aluminum• Reactive Gas: Oxygen• Sputtering Gas: Argon
University of ArkansasFayetteville, Arkansas 72701
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Equipment Used
• USB 4000» Interprets and captures an optical signal from the ICM 10 system» Compact and usb operated
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Software Used
• System Software:» Used to vary power and gas flow rates
• Spectrasuite:» Used to with USB 4000 to collect optical data
University of ArkansasFayetteville, Arkansas 72701
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Experiment
• Created recipes:» 4 Variables:
• Pressure: 2-8 mtorr with 3 mtorr increments• Power: 4-6 kW with 0.5 kW increments• Total Gas Flow: 40-70 sccm with 10 sccm increments• Oxygen Partial Pressure: 35-75% with 5% increments
» Time per run: 100 seconds» Integration time: 2 seconds» Scans per run: 1» Total scans: 540+
University of ArkansasFayetteville, Arkansas 72701
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Results
• Peak identification:» Unable to locate Aluminum peaks» Many Argon peaks» Few Oxygen Peaks
• Representative peaks:» Argon peak at 763.51nm » Oxygen peak at 777.194nm
25% 45% 65%0
0.5
1
1.5
Varying Argon Partial Pressure
Ar 750.95 Ar 752.08
Ar 764.1 Ar 801.95
Ar 843.04
4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 60
0.5
1
1.5
Varying PowerAr 750.95
Ar 752.08
Ar 764.1
Ar 801.95
Ar 843.03
1 2 3 4 5 6 7 8 90
0.5
1
1.5
Varying PressureAr 750.95
Ar 752.08
Ar 764.1
Ar 801.95
Ar 843.03
40 45 50 55 60 65 700
0.5
1
1.5
Varying Total Gas FlowAr 750.95
Ar 752.08
Ar 764.1
Ar 801.95
Ar 843.03
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Results
• Argon Trends» Predictable
• Increasing power=increasing intensity• Increasing oxygen partial pressure=decreasing intensity• Increasing pressure=slight increase in intensity
» Outliers caused by pressure changes due to oxygen reactions
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Results
• Oxygen » Expected trends:
• Linearly increasing oxygen intensity with increasing oxygen partial pressure• Increasing oxygen intensity with increasing power (graphs)• Fairly consistent results at higher pressures
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
Results
• Oxygen » Notable:
• Very low oxygen intensity at 50 sccm throughout experiments• Peak in oxygen intensity after 4.5-5 kW for 50 sccm• Unusually low intensity at 6 kW for Pr2• At higher powers Pressure didn’t have much effect
» Jumps:• Between 55%-75% Oxygen at Pr2Tg40Pw4• Between 50%-60% Oxygen at Pr2Tg60Pw4.5• Between 55%-60% Oxygen at Pr2Tg50Pw4• Between 35%-55%Oxygen at Pr2Tg40 jump from Pw4 to 4.5• Between 55%-65%Oxygen at Pr2Tg40Pw4• Jump in intensity from 2 to 5mtorr for Tg50 all powers• Jump in intensity from 2 to 5mtorr for Tg60Pw4
University of ArkansasFayetteville, Arkansas 72701
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Conclusion
• Study jumps in oxygen intensities » Target poisioning» Pressure and power changes
• Further experiments:» Hysteresis studies» observing aluminum vs. oxygen intensities» Test theories in deposition runs» Compare with Langmuir probe data
University of ArkansasFayetteville, Arkansas 72701
www.uark.edu
REU: Mechanical EngineeringUniversity of Arkansas
July 20, 2009
Questions?» Questions?