Combinatorial RF Magnetron Sputtering for Rapid Materials Discovery: Methodology and Applications

Transcription

1 Combinatorial RF Magnetron Sputtering for Rapid Materials Discovery: Methodology and Applications Philip D. Rack,, Jason D. Fowlkes, and Yuepeng Deng Department of Materials Science and Engineering University of Tennessee

2 Outline Sputter Deposition Combinatorial Thin Film Sputtering System Process Model Combinatorial Applications Cr-Fe-Ni Phase Diagram Determination Cu-Ni Carbon Nanofiber Catalysts for PECVD Bulk Metallic Glass Alloy Development YAG:Gd Solid State UV Emitters Summary

3 Sputtering Substrate Angular Distribution I ( θ ) = I cos( θ ) Positive Glow 1V 45 Ar + Ar + Dark space Target V Self bias Target 9

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5 Rf Magnetron Sputtering System Load-lock chamber

6 Simultaneous 3 Source Sputtering substrate Source 2 Source 1 Source 3

7 Angular Distribution Modified Cosine Distribution I ( θ ) = I ( θ ) cos n n~1 Film Thickness (nm) Ni Uniform Film Cu Uniform Position (cm) Target

8 θ substrate Ф Process Modeling r Input variables: Source power, voltage, current Material sputter yield Source tilt angle Substrate position Source time Determines substrate composition as a function of position cosθsinθdφdθ { 1[ ]} PtS n C P 36 9 ( n+ 1cos ) φcosθ j k i 3 j k i 3 sinθdφdθ Vq = = = = ntotal n = i = ΔrΔθ 2 j= 1 i= 1 j 1 i 1 2π r j = = i j

9 MATLab Process Model Binary Composition Profile Ternary Composition Profile Al Thickness Modeling Al Zr Cu Zr Cu

10 Fe-Ni-Cr Ternary Phase Diagrams Co-sputter Fe (16W), Cr (6W), Ni (6W) onto (1 1 2) single crystal sapphire substrates Anneal 2, 4, 6, 8 o C for 2 hours Rapid synchrotron fluorescence and XRD measurements Future Work: Nano-indentation

11 With Pharr et al. Non-Equilibrium Ternary Phase Diagrams (Fe-Ni-Cr) synchrotron beam 12 kev Fe Ni Cr CCD (diffraction) detector Fluorescenc e detector

12 Modeled versus Measured Composition Measured Composition Space Cr Modeled Composition Space Cr Fe Ni Fe Ni

13 Phase Diagram Temperature Evolution As deposited 2 o C 4 o C 6 o C 8 o C Equilibrium

14 Phase Analysis versus Temperature

15 Carbon Nanofiber Catalyst Cu-Ni Alloy Modeled Results Alloy Strip Deposited on Si Ni Cu With Klien et al. Atomic Percent (Cu & Ni) Measured Results Distance from Center (cm)

16 1 at% Cu Carbon Nanofiber Catalyst Cu-Ni Alloy 2 at% Cu 37 at% Cu 8 at% Cu 9 at% Cu PVX Si (15A) ITO (15A) 25nm Glass substrate With Klien et al. The morphology and shape of vertically aligned carbon nanofibers are a strong function of the composition of the Cu Ni catalyst particle that acts as the nucleation site for individual fiber growth. An optimum fiber geometry is realized at 8% Cu.

17 Experimental Procedure Sputtering Conditions Base Pressure 1.1x1-6 Torr Sputtering pressure: 3mTorr Argon Zirconium power: 225 W, Sputter yield:.7 Copper power: 5 W, Sputter yield: 2.3 Aluminum power: 26 W, Sputter yield: 1.2 Time: 2 hours Vacuum Anneal 1, 2, 3, 4, 5 o C for 1 minutes, 8 o C for 3 minutes XRD after each anneal

18 Composition Modeling Al Cu Al Zr Cu Zr

19 XRD Pattern of As-deposited Film 45 Al XRD integrated Intensity (arb. unit) Zr Cu Zr Cu θ (degree)

20 Position 1 11 Al Zr Cu Intensity (arb. unit) C 5C 4C 3C 2C 1C 1 5 as-deposited θ (degree)

21 XRD after 5 o C Anneal Inte n s ity ( arb. u nit) Zr Al Cu θ (degree) 1

22 XRD after 8 o C Anneal Intensity (au) Zr 2 Cu Cu Zr Cu-Rich Zr- Rich θ

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24 Y 3 Al 5 O 12 (YAG) Sputter Deposition Initial sputtering conditions: Yttrium Aluminum Oxide gradient: Reactive Sputtering (metallic mode) Power (Y)= 8W; Power (Al)=12W Flow rate (Ar) = 25sccm; (O 2 ) = 1.4sccm Total pressure = 3mTorr Time = 3min Position (mm) Al/Y ~

25 Al/Y ratio and (Al+Y)/O ratio vs. position on gradient Yttrium Aluminum Oxide films Al / Y (Al+Y) / O Position (mm).65

26 X-ray Diffraction Intensity of YAG Thin Films 4 unannealed Intensity (a.u.) 3 2 YAG (4) YAG (42) 1C 1hrs annealed YAG (422) Theta (degree)

27 Sputtering YAG:Gd Yttrium Aluminum Garnet ( 4 layer): Reactive mode Power (Y) = 8W; Power (Al) = 13W; Flow rate (Ar)=25sccm; Flow rate (O 2 )=1.4 sccm; Total pressure = 3mTorr; Time = 12.5min Gadolinium ( 3 layer): Metallic mode Power (Gd) = 6W; Flow rate (Ar) = 2sccm; Total pressure = 3mTorr; Time = 4min or 8min

28 SEM micrograph of multilayer Gd doped YAG thin films Gd-3 YAG-4 Gd-2 YAG-3 Gd-1 YAG-2 Si YAG-1

29 Gadolinium concentration vs. position for Gd doped Y 3 Al 5 O 12 films 14 Typical EDS Spectra 12 1 Gd_8min Gd at% Gd_4min Position (mm)

30 CL intensity vs. Gd concentration nm CL Intensity (a.u.) CL Intensity Wavelength (nm) Gd at.%

31 Mo Resistivity (μω cm) Binary Mo-W Electrodes (a) (b) (c) (d) Atomic fraction of W in MoW W Intensity / atomic fraction of W.15 W.2 W.35 W.45 W.5 W.55 W.65 W.75 W.8 W (a) 3 α-w, Mo (11), β-w (21) β-w (2) α-w (2) theta