1. University of Arkansas Fayetteville, Arkansas 72701 www.uark.edu Plasma Diagnostics for the Deposition of Nanomaterials Jay Mehta Undergraduate Student, University of Arkansas, Fayetteville, Arkansas 72701, USA Faculty Mentor: Dr. Matthew H. Gordon Associate Professor of Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA Ph.D. Graduate Student Mentor: Sam Mensah Graduate Student, University of Arkansas, Fayetteville, Arkansas 72701, USA REU: Mechanical Engineering University of Arkansas July 20, 2009

2. University of Arkansas Fayetteville, 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

3. University of Arkansas Fayetteville, 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

4. University of Arkansas Fayetteville, 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

5. University of Arkansas Fayetteville, 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 (Al 2 O 3 ) Target: Aluminum Reactive Gas: Oxygen Sputtering Gas: Argon

6. University of Arkansas Fayetteville, Arkansas 72701 www.uark.edu Equipment Used USB 4000 »Interprets and captures an optical signal from the ICM 10 system »Compact and usb operated

7. University of Arkansas Fayetteville, 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

8. University of Arkansas Fayetteville, Arkansas 72701 www.uark.edu 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+

9. University of Arkansas Fayetteville, Arkansas 72701 www.uark.edu 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

10. University of Arkansas Fayetteville, 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

11. University of Arkansas Fayetteville, 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

12. University of Arkansas Fayetteville, 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

13. University of Arkansas Fayetteville, Arkansas 72701 www.uark.edu 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

14. University of Arkansas Fayetteville, Arkansas 72701 www.uark.edu REU: Mechanical Engineering University of Arkansas July 20, 2009 Questions? »Questions?