Full-screen mode Popup controls. Overview of the microscope user interface, TEM User Interface and TIA on the left and EDS on the right

Transcription

1 Quick Guide t Operate FEI Titan Themis G2 200 (S)TEM: STEM mde Susheng Tan Nanscale Fabricatin and Characterizatin Facility, University f Pittsburgh Office: M104/B01 Benedum Hall, , sut6@pitt.edu I. Befre starting a sessin: II. Lg in t yur instrument sessin at Micrscpe User Interface The micrscpe peratin interface cnsists f three prgrams: 1. TEM User Interface: general micrscpe peratin and the display f live TEM image 2. TEM Imaging & Analysis (TIA): image acquisitin and analysis 3. Esprit: EDS acquisitin and analysis (Bruker spectrmeter system) Cntrl panel buttn functin display Full-screen mde Ppup cntrls Overview f the micrscpe user interface, TEM User Interface and TIA n the left and EDS n the right III. Check and cnfirm the fllwing cnditins: a. Gd Octagn (clumn) vacuum (< 20 lg, <10-7 Trr), Prjectin (camera chamber, < 30 Lg) b. Gd liquid nitrgen level (> 10%) c. Clse the clumn valve befre sample hlder insertin/remval d. Reset the stage (hlder) befre sample hlder insertin/remval IV. Chse Sample Hlder Wear glves when handling a sample hlder t prevent cntaminatin. Never tuch the brass part f the hlder. There are three types f sample hlder available fr different applicatin: 1. Single-tilt: mrphlgy bservatin, EDS acquisitin 2. Duble-tilt (lw backgrund): mrphlgy bservatin, detailed crystalline material study, EDS acquisitin

2 3. Tmgraphy (lw backgrund): similar t single-tilt hlder but with lwer hlder prfile allwing high alpha tilt angle V. Hlder Insertin/Remval When Inserting a Hlder 1. Align the hlder guide pin with the Clse line mark n the gnimeter cver and insert the hlder straight in t the stp f the stage lad lck area (LED will light up in Red) 2. Keep finger pressure n the hlder (n rtating!!) t activate pumping prcess 2. Wait fr the lad lck t pump dwn (until Airlck cycle times ut, ~3 minutes) 3. Slwly and smthly rtate the hlder Cunterclckwise t its stp psitin and let it gently int the micrscpe clumn area (Octagn: < 20 Lg) 4. Wait fr 1 minute, and then turn ff the Turb pump by clicking Turb On buttn (clr changes frm yellw t gray) When Remving a Hlder: 1. Clse clumn valves by clicking Cl. Valves Clsed buttn (clr changes frm gray t yellw!) 2. While pressing the purple stage cver dwn, slwly pull the hlder straight ut till its stp 3. Rtate the hlder clckwise till its stp 4. Wait fr 30 secnds, then 5. Slwly pull the hlder straight ut while yu are still pushing the purple stage cver dwn VI. Find Specimen Eucentric Height at TEM Mde 1. (Optinal) Lad the mst recent alignment frm Wrkset Alignment File, e.g. Rutine 200kV 2. Wrkset Setup FEG Registers, set the mst recent FEG Registry, e.g. RutineTEM 200kV 3. Set Specimen Eucentric Height (Z) 1) Open clumn valves by clicking Cl. Valves Clsed buttn (clr changes frm yellw t grey!) 2) Press the Eucentric fcus buttn and nrmalize all (L2) buttn 3) Set at a lwer magnificatin (~10,000x) and find a reference bject 4) Activate the stage Wbbler (L1) and bserve bject mvement 5) Reduce the mvement by mving the Z up r dwn 6) Repeat steps 3 5 at higher magnificatin (~50,000x) t fine tune the z psitin Nte: if yur sample is crystalline, then cnverge the beam, mve Z up r dwn until diffractin pattern cnverge t the center spt VII. Tune Prbe Cs and Image in STEM Mde 1. Wrkset Setup FEG Registers, set the mst recent FEG Registry, e.g. RutineSTEM 200kV 2. Select spt size 8 and Gun Lens 6 in FEG Cntrl (target Screen Current: ~30 pa) 3. Frm Wrkset STEM tab, set the camera length t 128 mm) 4. Press the Eucentric fcus buttn and nrmalize all lenses 5. Select a suitable magnificatin, e.g. 225,000x 500,000x 6. Click Search t start scanning 7. Find amrphus area n a sample and bring it clse t fcus (within 200nm) by adjusting the CmpuStage Z. 8. Optimize the cntrast and brightness setting f the STEM detectr (adjust Cntrast/Brightness sliding bar t make the Signal mean in the range f 6000 ~ 10000) 9. Stp STEM scan, retract HAADF detectr 10. Carry ut a Direct Alignment with Diffractin mde ff 1) Press Diffractin buttn t turn Diffractin mde ff 2) Carry ut Direct Alignment: i. Check C2 lens aperture centering: Wrkset STEM (flaput) FOCUS select Intensity & Objective s that Intensity knb is functinal; turn Intensity knb back and frth passing beam crss-ver; if beam des nt expand/cntract cncentrically, center C2 aperture by activating Adjust C2 aperture ii. Pre-crrectr Beam Tilt: using MF-X and Y t make the beam wbble cncentrically (r stp wbble by setting the FOCUS adjust knb and then use MF-X and Y t mve the ht beam spt t the center f

3 the beam disc) iii. Pre-crrectr Beam Shift: using MF-X and Y t center the beam iv. Click Dne t accept the new alignment 11. Carry ut a Direct Alignment in Diffractin mde 1) Press Diffractin buttn t switch back t STEM diffractin mde 2) Diffractin Alignment: Center the diffractin disk using MF-X and Y knbs 3) Pre-crrectr Beam Tilt: using MF-X and Y t make the beam wbble cncentrically (r stp wbble by setting the FOCUS adjust knb and then use MF-X and Y t mve the ht beam spt t the center f the beam disc) 4) Click Dne t accept the new alignment 12. Use the Rnchigram t crrect cndenser astignatism 1) Wrkset Camera Insert CETA camera Raise Phsphrus screen (R1) Search (t view the Rnchigram) 2) Frm Stigmatr OCX, activate A1 carse Stigmatr; Adjust FOCUS: if riented lines are bserved (Figure (a) at right), adjust A1 t crrect astigmatism carsely s that a symmetric pattern can be seen n bth underfcus and verfcus sides (b) and at the right fcus Rnchigram is flat 3) Frm Stigmatr OCX, activate cma B2; Adjust FOCUS crss underfcus and verfcus: if pattern changes asymmetrically, then adjust Cma Free B2 t crrect cma s that a symmetric pattern can be seen n bth underfcus and verfcus sides and at the right fcus Rnchigram is flat 4) Click Dne t accept astigmatism crrectin values 5) Stp CETA camera view Figure : (a) image f the Rnchingram with a fairly large amunt f A1 astigmatism; (b) the Rnchingram, slightly defcused, when A1 has been crrected t a gd level. Further crrectins is easier n the image at this level. 13. Insert HAADF detectr 14. Click Search in STEM Imaging (ptinal, and bring the sample t fcus using Z height cntrl) 15. Watch the STEM image, carefully adjust fcus (C1) and finely crrect astigmatism with Cndenser Stigmatr t ptimize image quality 16. Acquire and save STEM images VIII. EDS (spectrum, line, and map) Acquisitin Figure : (a) image f the Rnchingram that shws cmma as the area arund 5 clck appears at much higher magnificatin than the rest; (b) the Rnchingram, slightly defcused, when cmma has been crrected t a gd level. Only the area arund 11 clck is at slightly less magnificatin than the rest f the Rnchingram perimeter. 1. If EDS sftware has nt been launched yet, start the Bruker Esprit sftware by clicking icn in the Windws quick launch panel, lg in with default username (edx) and passwrd (edx)

4 2. Set up EDS acquisitin parameters: Maximum energy (e.g., 20 kev) in Spectrmeter page and Image reslutin (e.g., 2048), detectr (HAADF), Mapping Dwell time (e.g., 40 us) in Imaging system page. 3. Navigate t the EDS peratin, e.g., Objects/HyperMap, click New in Image scan panel t btain a STEM reference image. Drag the crner f the bx t define an area t cllect fast map and activate Drift crrectin buttn. Drift crrectin 4. Click the triangle icn t the right f Acquire buttn t set up Measuring time. Manual: acquire EDS hypermap until user clicks Stp (recmmended chice). Measuring time: set up ttal acquisitin time. Cycles: set up number f frames t acquire and integrate fr EDS hypermap. Nte: if Cycles is chsen, clicking Stp nce will terminate acquisitin after the current frame and duble-clicking Stp will terminate acquisitin immediately. Nte: reducing the gun lens number and beam spt size number can increase the beam intensity, thus enhances the x-ray cunts per secnd. 5. Click Acquire t cllect hypermap f selected area. A status bar with remaining time is displayed in the upper right crner f the sftware interface. Select elements (multiple selectin) frm flap-ut peridic table t mnitr hypermap acquisitin prgress. 6. Save hypermap database and individual element images. 7. Use area selectin bjects t select full r partial map fr spectrum calculatin and click Spectrum tab t shw spectrum. 8. Use Quantify t calculate the weight r atmic percentage f selected elements: click the methd in grey under Quantify buttn, check Element identificatin, yu can chse Autmatic r select elements using Preset list. Click Quantify buttn t calculate the elemental percentage.

5 Save data Select element t mnitr during map Select area fr sum spectrum calculatin Element maps Save element IX. Finish yur micrscpe sessin Retract HAADF detectr and return t TEM mde by simply lading the TEM registry, e.g. RutineTEM 200kV Click Cl Valves Clsed buttn in Setup>Vacuum t clse the clumn valves Retract CCD (BM-ceta) camera Lwer the flurescence screen (R1 buttn). Put the rubber cver n. Frm Reset panel f Search> Stage>Cntrl page, click Hlder t reset stage t center While pressing the purple stage cver dwn, slwly pull the hlder straight ut till its stp Rtate the hlder clckwise till its stp Wait fr 30 secnds Pull the hlder straight ut while yu are still pressing the purple stage cver dwn Remve and save yur specimen Insert the empty single tilt hlder in t gnimeter Transfer yur data t yur shared drive flder Lg ff yur micrscpe sessin via FOM Page 5 f 8

6 Bright-Field (BF) detectr STEM detectrs The retractable BF detectr cnsists f a slid-state detectr with a diameter f 10 mm. WARNING: POTENTIAL DAMAGE! The retractable BF detectr can be damaged by a very high electrn dse. If yu are using the detectr with a very high beam current (e.g. fr X-ray mapping), change t a high camera length s the central-beam disk is large and the electrn dse per detectr area is nt t high. Imprtant nte n the retractable BF detectr. The area cvered by the BF detectr is larger than the hles in the DF2 and DF4 detectrs. Cnsequently, when yu set cntrast and brightness with the BF inserted but the DF retracted and then insert ne f the DF detectrs, the area f the BF detectr receiving signal will be much reduced and typically n BF signal is bserved any mre. Set the cntrast and brightness again (AutCB) and the signal will re-appear Schematic drawing f the retractable BF/DF detectrs Dark-Field (DF) detectr The retractable DF detectrs (there are tw with different diameters) are annular slid-state detectrs with uter diameters f 24 mm and inner diameters f 2 (DF2) and 4 (DF4) millimeters. The acceptance angles f the DF detectrs (inner and uter) are determined n the ne hand by their dimensins (inner and uter radius) and n the ther hand by the camera length chsen (the values are given by the arc tangent f the relevant radius divided by the camera length - in mm f curse). These detectrs are lcated abve the retractable BF detectr. High-Angle Annular Dark-Field (HAADF) detectr The HAADF detectr is an annular detectr cnsisting f a scintillatr-phtmultiplier. This detectr is placed in a husing abve the prjectin chamber and is mved in and ut. This detectr has been ptimized fr tw aspects, in rder t allw atmic-reslutin STEM imaging (n FEG instruments) : Single-electrn sensitivity High acceptance angles The inner acceptance angle can be seen directly frm the shadw f the detectr n the flurescent screen (when it is inserted), the uter acceptance angle is five times the inner angle. Page 6 f 8

7 STEM Acceptance angles The table shwn belw gives the minimum (inner) and maximum (uter) acceptance angles f all fur STEM detectrs fr the current situatin (highlighted in red) n the micrscpe when run n-line. Nte: The maximum acceptance angles fr the DF2 and BF assume that the DF4 r DF2 and DF4, respectively are NOT inserted. If these are inserted the maximum acceptance angles fr the DF2 r BF becme equal t the minimum acceptance angles f the detectr blcking the ther ne (fr DF2 the DF4; fr BF the DF2 r DF4). Page 7 f 8

8 SPECIFICATIONS (Highlights): Accelerating vltages: 80 and 200 kv Ultra stable, high brightness X-FEG (brightness: 1.8 x 10 9 A/cm 2 /sr) X-FEG prbe current: 0.9 na in 0.2 nm spt and 14 na in 1 nm spt Cs DCOR prbe crrectr fr sub- Å reslutin in STEM mde TEM pint reslutin and infrmatin limit: < 0.11 nm STEM reslutin: 70 pm (Cs crrected) EDS energy reslutin (Windwless Super-X EDS detectr system with utput cunt rate up t 200 kcps): 136 ev fr Mn-Kα and 10 kcps (utput) 140 ev fr Mn-Kα and 100 kcps (utput) Detectrs: High angle angular dark field (HAADF) detectr fr STEM 4 n-axis ADF/BF detectrs including 4 Quadrant ADF fr differential phase cntrast (DPC) imaging Ceta 16M CMOS camera Specimen Hlders: FEI CmpuStage single tilt hlder FEI CmpuStage high-visibility, lw-backgrund duble tilt hlder (±35 tilt range fr alpha and ±30 tilt range fr beta) Fischine tmgraphy hlder mdel 2021 (up t ±70 ) Page 8 f 8