SEM In-situ Experiments for Breakdown Study Tomoko Muranaka T. Blom*, K. Leifer*, V. Ziemann Department of Physics and Astronomy Department of Engineering Science* Uppsala University Sweden Ångström Laboratory, Uppsala, Sweden November 30, 2010 Supported by the 7th European Framework program EuCARD under grant number 227579
Ideas of Experiments Basic Idea: Reproduce high gradient electric field conditions in micro meter range, 1 GV/m = 1 kV/μm SEM Chamber Sub μm Gap meas. Needle V Bias Sample A pA current meas. Scanning Electron Microscopes (SEM) open an opportunity to investigate local processes during breakdown “Mesoscopic” field emission and breakdown measurement and observation UPPSALA UNIVERSITET 2 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Experimental Setup Experimental setup Philips XL30 ESEM FEG Cu sample: 1.2 mm diameter, 0.5 mm thickness A piezomotor (Piezo LEGS® Linear 10N Non Magnetic Vacuum) A tungsten needle attached to the rod of piezomotor Positive / Negative bias voltage on the needle Setup in SEM at 0 deg. tilt (drawing) Gap calculator program UPPSALA UNIVERSITET Setup in SEM at 30 deg. tilt (drawing) 3 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Focused Ion Beam to go further SEM FIB Omniprobe Sample position UPPSALA UNIVERSITET FEI Strata DB235 4 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
In-situ Breakdown W tip to flat surface (≈ 1μm) UPPSALA UNIVERSITET W tip to flat surface (≈ 1μm) Up to -1000V on the tip 5 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Damage inside the surface Pt Interesting area FIB Pt coating Staircase milling UPPSALA UNIVERSITET 6 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Cross Section of the BD Area (1) UPPSALA UNIVERSITET 7 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Cross Section of the BD Area (2) UPPSALA UNIVERSITET 8 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Surface Manipulation 3D structure: By controlling gallium ion beam size and intensity, one can ”mill” a surface of samples with nm resolution and create surface corrugations, pillars and tips. Images from two different angles: The image of the sample can be observed both by SEM and FIB simultaneously. FIB beam line is at an angle of 52 degrees to the SEM beam line. UPPSALA UNIVERSITET 9 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch
Summary & Outlook Breakdown in the SEM Accurate gap control Cross section images of BD area Artificial surface preparation by FIB Field emission measurement Cu tip - Cu surface Well defined tip (sharp - blunt) Geometrical dependence (surface feature) Controlled breakdown UPPSALA UNIVERSITET 10 / 10 Nov 30 2010, XB10 T. Muranaka | tomoko.muranaka@cern.ch