Optimizing Lift-Out. Cheryl Hartfield. Senior Applications Specialist, Omniprobe

Transcription

1 Optimizing Lift-Out Cheryl Hartfield Senior Applications Specialist, Omniprobe

2 Lift-out Solutions Lift-out involves multiple aspects How you cut: Total Release Milling* How you lift: Plan-View TEM** How you attach: Atom Probe Preparation* Address many applications: Quality imaging for holography, high resolution TEM (Short-Cut grid attach for backside milling)* Materials characterization of particles, nanowires (Short-Cut grid attach)* Patents issued* or pending**

3 How You Cut: Total Release 3

4 DIRECT TEM SAMPLE EXTRACTION IN THE FIB PHEMT T-gate Pt deposition Attach probe with Pt patch 10mm Expose slab Remove slab from wafer TMM 11/25/96 MATERIALS SCIENCE LABS

5 Total Release Wedge Cuts made using 2 angles of incidence Most common shape for Total Release (all cuts completed before attaching needle) 3um 5um 20um Commonly used for atom probe prep, plan-view, and high volume sampling (fast lift-out)

6 Lamella vs Wedge (Chunk/Block) Automated overnight milling Warping during thinning or Pt welding Reduced area for welding Shifting or falling over with one free end Robust sample thickness Large area for welding Faster thinning Possible redeposition Possible position change

7 Milling High Aspect Ratio Trenches Use optimum parameters to avoid redeposition: Parameter Good Bad Angle of Incidence Lower Higher Passes/Layers (Constant Dose) More Less Dwell Time (Constant Dose) Less More Current Less More 3/13/2011 7

8 Use Guides for Sample Position 3/13/2011 8

9 Use Guides for Sample Position 3/13/2011 9

10 Use Guides for Sample Position 3/13/

11 Total Release Benefits Fast: less milled area = less process time Best for pre-lift orientation moves Plan-view and sideways milling Short-Cut grid attach for backside and atom probe Eliminates/reduces blind view milling Ideal for many applications 11

12 Time Comparison Creating a 10µm x 5µm lamella in Si-based material using a modern FIB Lamella Total Release FIB TIME 60 minutes vs 8 minutes

13 FIB Preparation of TEM Lamella Creating a 10µm x 5µm lamella in Si-based material using a modern FIB From Sample. Omniprobe Solution Minutes FIB Milling Total Release 8.To Grid Ready for Final Thinning INLO + Grid Attach Positioning the stage* 2 Positioning the tip 1 Attaching the tip (IBID) 3 Lift-Out 1 Shaft rotation* 1 Grid positioning* 5 Contacting the grid 3 Grid attach (EBID) 4 Tip detach 3 TOTAL FIB TIME: 31 minutes * Timings specific to plan-view samples

14 FIB Preparation of TEM Lamella Creating a 10µm x 5µm lamella in Si-based material using a modern FIB Preparation Comparison Minutes Omni H-Bar EXLO Pre-FIB Prep 30 Thinning to 1um Lamella Total Release Milling 8 In Situ Lift-Out 23 FIB Time Before Final Thinning FIB Final Thinning Total FIB Prep Time Ex Situ Lift-Out 15 Total Prep Time

15 Wedge Visualizer W=6 W=4 D=7 D=6?? 3/13/

16 Shallow Wedge Parameters U-Cut Release Cut AOI = 52 o AOI = 0 o 4 um 1 um 5 um 2.2 um 1 um 0.5 um 10 um um 2.8nA 1us, 50% OL Depth Relatively Low Currents 2.5um 1nA 1us, 50% OL 16

17 Total Release for Lamella What about leveraging automated milling routines? J or L cut T cut 10µm

18 T-shirt Cut T-Shirt Total Release 3/13/2011 Acknowledgement: Kurt Langworthy, CAMCOR, University of Oregon 18

19 How You Lift: Plan-View Samples 3/13/

20 Plan-View Samples (and Sideways) Contact target Weld and lift Align grid and sample Shaft Rotation Weld, release the tip

21 Plan-View FIB X Solution 3/13/

22 Plan-View Movie Achieving Plan-View Samples in 30 Minutes, Start to Grid 3/13/

23 Total Release Applications..Beyond Lamellae 23

24 EDS Maps Before Lift-Out Al peak indicates significant signal comes from the bulk material Al substrate After Block Lift-Out Cu-Ag solder M. Schaffer, J. Wagner, Microchimica Acta 161, 421 (2008) 24

25 Tomography Lift, Locate, Pattern, Analyze 1 2 Lift Locate 3 4 Pattern Analyze 25

26 FIB Tomography Orthogonal cuts made, followed by oblique cuts. Used for in situ 3D analysis (tomography). M. Schaffer, J. Wagner, Microchimica Acta 161, 421 (2008)

27 Thank You 27