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Metallic Nanoneedles Arrays for “Lift-Out” TEM Sample Preparation

Metallic Nanoneedles Arrays for “Lift-Out” TEM Sample Preparation. Romaneh Jalilian, Brian Miller, David Mudd, Neil Torrez, Jose Rivera, and Mehdi M. Yazdanpanah NaugaNeedles LLC, Louisville, KY. Purpose. Introduction to NaugaNeedles technology Review Standard probe for TEM Lift-out

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Metallic Nanoneedles Arrays for “Lift-Out” TEM Sample Preparation

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  1. Metallic Nanoneedles Arrays for “Lift-Out” TEM Sample Preparation • Romaneh Jalilian, Brian Miller, David Mudd, Neil Torrez, Jose Rivera, and Mehdi M. Yazdanpanah • NaugaNeedles LLC, Louisville, KY

  2. Purpose • Introduction to NaugaNeedles technology • Review Standard probe for TEM Lift-out • Using Needle Array to sharpen W probe (Needle-Tipped Probe ) • Needle-Tipped Probe for TEM Lift-out • Summary

  3. 10 mm An Introduction to NaugaNeedles Technology Silver coated cantilever Ga droplet 5 mm Time lapse images of an Ag2Ga needle growing from a melted drop of gallium [M.M. Yazdanpanah, J. Appl. Phys. Vol. 98 (2005)]

  4. Ag2Ga Nanoneedles • Properties • Mechanical • Spring constant (K) = 0.1 - 1 (N/m), • Resonance frequency (f0 ) = 20 -10 (MHz) • Young’s modulus (E) = 84 ± 1 (Gpa) • Electrical • Electrical Resistivity (ρ)= 2 × 10-7 (Ωm) • Max Current Density (J) : 1.5 × 10-11 (A/m2 ) • Thermal • Melting point (experimental) = 950 oC • Resistive to Reactive Ion Etching (RIE) • Applications • AFM, SGM, SECM, EFM, STM, nano-cantilever, …

  5. Example of Nanoneedle Application for AFM (EFM) Enhancement of electric force microscopy (EFM) imaging on CNT nano-composite [M. Zhao et al, Nanotechnology 21 (2010) 225702

  6. NaugaNeedles Array Technology Overall SEM view of a NaugaNeedles array 5 µm Close up view of a coated needle in the array 40 µm • Grow arrays of Ag2Ga nanoneedles on prefabricated structures • Nanoneedles Diameter (W, Ag, Cr, Pt coated) : 500nm- 1000nm • Nanoneedles Length : 15µm to 50µm • Array contains minimum of 1000 nanoneedles [R. Jalilian et al, Nanotechnology 22 (2011)]

  7. Problems With Lift-Out Using Standard Tungsten Probes • Sharpening process usually takes several minutes • A tungsten probe may be replaced after a few uses • The extended sharpened tungsten tip is on axis with the tungsten probe, which limits application

  8. Fabrication of Needle-Tipped Probe Weld a Needle ~ 1 min Cutting from base ~ 1 min Remaining needle Find a needle in the array and approach the probe ~ 3 min The Needle-Tipped probe is ready to use 2 µm 2 µm 5 µm (d) (c) (b) (a) Locate a selected nanoneedle on array Rotate the needle array at the desired angle Weld a tungsten probe to the needle Cut the needle free from the array substrate

  9. Lift-Out Process Using Needle-Tipped Probe

  10. Improved Sample Viewing Using Needle-Tipped Probes Clear view of connection in FIB when the needle is in contact with the specimen Improved sample viewing in SEM when the needle is in contact with the specimen

  11. Needles-Tipped Probes are Flexible and Durable Before bending First bending test After cutting , back to original shape Bending test after second welding 1 µm 1 µm 1.7 µm 1.8 µm (d) (a) (b) (c) • Needle bend without plastic deformation • Keep similar properties after cutting and re-welding

  12. Vibration Test of the Welded Needle During Sample Movements The Welded Needles can survive severe mechanical vibration and shocks

  13. A Nano-Fork Made from Needles for Weldless Lift-Out The movie demonstrates the use of fork made by needles for weldless lift-out

  14. Advantagesof Using NaugaNeedles Array for Lift-Out • Better mechanical properties than W probe • More FIB uptime due to less W tip changes • User maintained tip by sharpening inside TEM • Curve the shape for best sample viewing • Needles have constant small diameter • Needles flexibility during touch down • No sample welding using nano-Fork

  15. Summary • Introduced Ag2Ga Nanoneedles technology • Reviewed Nanoneedles properties and application • Demonstrated W probes sharpening using needle array • Demonstrated Lift-Out using Needle-Tipped Probe • Examined the Needle-Tipped Probe properties • Reviewed Needle-Tipped probes advantages for Lift-Out

  16. Thank You

  17. Procedure • Needle-Tipped Probe fabrication: • Locate a nanoneedle on array in the TEM system • FIB-weld the W probe to the nanoneedle • FIB-cut the needles from the array • Needle-Tipped Probe for Lift-Out: • Bring the Needle-Tipped Probe in contact • Weld the nanoneedle to the sample • FIB-cut the specimen • Transfer the specimen to TEM grid • FIB-cut the Needle-Tipped Probe

  18. More examples of Needle-Tipped probe in action

  19. Robust Nanoneedles, Less Buckling The needle pushed against the specimen  The specimen displaced severely  But Nanoneedle buckles slightly Needle Slightly buckles 5 µm

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