Ion gun imaging

• Want to use external raster control for 20-066 ion gun control to allow SE imaging for focusing and alignment
• Omicron software does not allow external raster to be enabled
• Install PHI software (from floppy disk!!) version 3.0A 1997
• C:\program files\PHI\EXE
• edit IonGunCrtl.ini

[Ion Gun Control]

ComPort=COM6

RS485ResponseTime=1000

IgunAddress=3

NoHardware=0

ModelNumber=11-066

BlankingOptics=1

[END]

Com port set to COM6, address used by Omicron. Other params left at defaults

Software seems to work.

Pressure control

• Phi software does not generate setpoint voltage
• switch RVG50C Pfeiffer controller to INT setpoint
• knob 1.0 = 13 mPa
• 1.5 = 20 mPa
• 2.0 = 26.5 mPa
• Leak valve needs 2.0 turns for ~ 30 mPa (as of 12/2/13)

PHI software raster

raster is not centered on offset, ie changing raster size shifts sputter area

Y raster half of X gives approximate square image for 30 degree tilt sample

Ion Gun Align

• Use Si 10 um grid 30 degree tilt, sputter off O and C.
• SEM multiplier off and beam blanked.
• Hemisphere CAE 10 eV at 56 eV, entrance slit  3, 2 mm circle
• detect SE from ions
• At 3 kV ions, best focus ~ OBJ 62
• Currents to sample (no bias)
• cond 100, 55 nA
• 95, 85 nA
• 90, 166 nA
• 85, 310 nA
• 80, 700 nA
• around 60, 6.6 uA
• spot center ~ x=1.3, y=0 (at cond 90 obj 70, only weakly dependent)

make Foundry1 profile, 25 mA, grid 150, pressure 20 mPa

cond 85 obj 62 voltage 3000

Align after bake

This is the procedure for a full "service" alignment, this is not for daily fine tuning alignment

Simplified Column Alignment instructions

1. Put large featureless sample, at least 3-4 mm, such as Si wafer in stage, no tilt
1. Get image at 8 kV, focus on sample
2. open "Aperture Calibration" and "Calibrate Stigmation" windows (these only work in service mode)
1. Select probe current max
2. zero gun align and aperture align in service window AND user aperture window
3. zero stig and beam offset
4. All electronic offsets should be neutral
3. Get emission image, uncheck Condenser Normal box
1. all apertures should be evenly illuminated, circles will overlap
1. If circles are clipped, distorted, partial, mechanical source align is required
2. if illumination is good, mechanical source alignment is OK,go to next step
3. loosen 4 6 mm screws at top of column. do push-pull adjustments in X and Y to try to get uniform illumination. 
4. to the extent possible, center illuminated aperture pattern, however uniform illumination is more important than centering.
5. recheck condenser normal. Now large diffuse aperture images will change to sharp smaller circles. These should also be uniform. Reduce SEM contrast since these will be saturated.
6. slowly tighten all four screws to lock source. This will cause shifts, correct as needed to get good illumination with source locked. 

Best align with current filament state, 200 pA mode (60 um aperture)
gun 44.5, 27.5 aperture -47.0 -22.9
user aperture -4.0, -6.0
stig 5.7 19.5 balance X 81.3, 95.9 Y 69.6, 94.7

Best max current
gun 44.5 27.5 aperture -47.0 -22.09
stig 24.7, 39.0 bal X 84.1, 93.0 Y 74.3, 94.7

Condenser lens needs mechanical alignment. Here is emission image for 1 nA, 600 pA, 400 pA all 90 um aperture

clear shift with condenser excitation















Align gun, aperture, stig, stig balance for 120, 90, 60, 30 um apertures

Transfer rod to Prep Manipulator

1. Set manipulator position:
1. Top (vertical motion) micrometer: 11.05 mm
2. Z (horizontal insertion) screw: 105 mm (scale ends at 100, engraved on one support rod) There is also a red sharpie mark on the support rods
3. Rotary motion 300 degrees (red mark on top of support)
4. These positions are approximate, adjustment may be required to engage sample.
2. To transfer the sample to the stage: Slide the transfer rod forward until the long pins engage the rectangular hole in the side of the manipulator stage. 
1. If there is any resistance, adjust the height, insertion, rotation until the motion is easy.
3. The sample plate should slide into the dock on the manipulator.
1. If there is any resistance, adjust the height, insertion, rotation until the motion is easy.
2. Insert the sample plate fully, until the metal part of the transfer rod touches the dock, then rotate the transfer rod handle to open the jaws.
3. Now retract the transfer rod, leaving the sample plate on the manipulator dock.

Sample Introduction and Airlock

Here is the procedure to transfer samples from air to the long transfer rod in the prep chamber. From there samples can be moved either to the prep manipulator or to the parking carousel in the analysis chamber.

1. Start the "Prep" turbo pump, if it is not running already (see Turbo Pumps how to for details)
1. Start PV TurboViewer software on Auger-pxi. 
1. click connection wizard, set find multiple devices to 3 and click button, software should find three pumps. Drag window taller and click arrange. Click on speed display to toggle between rpm/Hz/% for speed. 
2. pump 001 is nano, 002 is prep/sample intro, 003 is ion gun
2. Prep turbo should reach 100% within a minute or two, power < 20 Watts, foreline pressue (push down arrow on ion gauge controller to see fore pressure) < 0.1 mBar.
2. Vent airlock
1. Close airlock pumping valve (large black plastic handle) and bypass pumping (small green valve handle). 
2. Open N2 vent supply valve (small green valve below table)
3. Turn off air lock ion gauge if on.
4. Open airlock vent valve (below airlock). You should hear gas flowing. Airlock pirani gauge should read about 780 torr (slightly above atmosphere).
5. Open air lock door. Do not let glass door fall open. 
3. Load samples
1. Up to 3 samples can be loaded. Use gloves and clean sample plates.
2. Normally sample surface is to the right as you face airlock. 
3. VT double-plate holders must face right
4. If flat sample plates will be heated on prep manipulator, load upside down (facing left) so sample surface faces heater after transfer.
4. Pump airlock
1. Close N2 vent valve
2. 
   

pBN VT heater test

Test of VT pBN heater plate

• Remove old sample, re-attach top plate, verify thickness of assembly and heater brushes
• 7.6 mm total, 2.9-3.0 from top of brush to bottom of top plate
• 17 ohm left brush (seen from handle) to ground. Right brush grounded.
• Sample Heating Selector to "Direct Current"
• Initial 1.6 V at 0.16 A (10 ohm), gentle pressure rise, manipulator TC increases linearly with time 22 to 28 C over 6 minutes, 0.25 W
• Next 3.24 V 0.40 A 1.3 W 8.1 Ohm
• 4.49 V 0.65 A 2.96 W 6.7 Ohm, temp rises slowly with time
• 5.73 V, 1.04 A, 5.96 W 5.7 Ohm, current rises to 1.18, pressure low 1e7 outgassing
• More tests
• Set 6.26 V 1.05 A Monday 9:23 am
• by 10:14 current limited at 1.49 A, 5.7s C 8.5 W, stage at 270 C
• pressure rose to 1e-7 then down to 2e-9
• increase current to 2.01 A, initial 7.43 V drops to 7.23 steady state, 14.5 W
• stage steady state 332 C. pBN heater uniform "cherry red" 
• contact bars also hot, darker red
• heat shield, top plate, sample straps do not glow
• pressure has dropped to 1e-9
• Set 1.49 A, 5.55 V increases to 5.70, initially 3.72 Ohm -> 3.83
• heater "incipient red" just at visible glow threshold
• steady state base 280 C
• 8.5 W

Photo of heater at 14.5 Watts, pBN "cherry red"

Approximate sample temp vs power for pBN VT holders

Prep chamber heater hints

• Prep chamber manipulator heater powered by TDK-Lambda power supply (60 V, 12.5 A) under system controller.
• push small button on far right under digital displays "out" to enable output
• adjust current and voltage knobs. Depending on load either current or voltage limit will control. Green LED near knobs shows which is limiting. 
• Set Sample Heating/Bias Selector switch to "Resistive" to connect the TDK supply to the pBN heater built in to the prep manipulator.
• This heater is ~ 30 Ohm cold, 5 A max current, 100 W max output
• Increase and decrease heater power slowly to avoid thermal shocks
• 1.45 A requires 27.6 V for 40 W, R ~ 19 Ohm (lower when hot). This gave ~ 525 C at thermocouople, sufficient to dewet Au/Si film at ~ 600 C
• There is a thermocouple attached to the sample plate dock. This temperature will be lower than the actual sample temp, and the difference will be greater when radiation is important, > 500 C.
• temperature will depend on sample properties such as emissivity since heating is by radiation coupling

Estimated temperatures for stage and sample vs power

• The side of the sample plate facing the heater must be flat (no sample, screws, clips, wires, etc.
• For simple plates with the sample mounted below, the sample can face the heater
• For this to work, put the sample in the airlock "reversed" or upside down. 
• The sample can be heated
• transfer to the carousel in the analysis chamber upside down. Then use the wobble stick to flip the sample over for inserting in the Auger/STM stage.
• Do not heat samples mounted with spring clips to high temp (> ~ 200 C) as this will anneal and damage the springs. Mount samples with spot welding for high T.
• VT double plates with direct or pBN heating may be inserted in the manipulator stage face up. 
• The plates can be heated using the manipulator pBN heater, or by using the VT heater since the  "fingers" on the manipulator contact the heating terminal.
• Set the selector switch to "direct current" to use the VT heaters.
• The top of the VT heating contact must be 3.6 to 3.7 mm above the bottom of the VT assembly, also the total thickness should be 7.6 mm
• adjust the VT plate if these distances are not correct. Using a badly set VT plate will bend the contact springs.

Ion Gun Operation

FIG-5 Setup

1. Start Diff Pump Turbo (pump control 3)
1. run for at least 10 minutes after reaching 100%
2. PV Turboviewer gives details, pump power should be <~ 10 W steady state
2. Start 20-066 ion gun control power supply (brown box in rack)
3. Start the Pfeiffer RVC050 controller (grey box above 20-066) with the white toggle switch in Set Point mode.
4. Start FIG5 control program
5. Open FIG5 differential pumping
1. system pressure should stay constant or drop somewhat
6. In software set mode to Standby then click the ON button
1. Standby means the filament will heat but no the ion acceleration voltage is OFF
2. Parameters in Orange are not at desired values, parameters in green are good. In standby mode it is normal for Energy, Condenser and Objective to be orange, since the ion accelerating voltage is off, as shown below. They go green when the gun is on (Etch/Neutralize)
7. Wait for the Extractor Pressure to drop below 1 mPa. This shows the gas pressure in the ion gun. Since the Ar valve is still closed, any pressure reading is due to outgassing. This should drop with time.
8. Once the ion gun has degassed, open the leak valve. Click the magnifying glass to get a big pressure display, put it where you can see it on the computer screen from the vacuum system.
1. Slowly (1/10 turn adjustments) open the leak valve. Wait for the pressure to start to rise, ie to several mPa. Also watch the system vacuum. This will rise from the 1e-10 or 1e-11 range into the 1e-9 range.
2. It should take 2-3 turns to open the leak valve. If you open the leak valve too far, too fast, you could cause the ion gauge, ion pump, SEM field emission source to shut down.
1. This is bad.
2. Do not do this. Open the value slowly
3. Open the valve until the pressure exceeds the setpoint, typically 20 mPa. Now the Pfeiffer should stat to regulate the pressure (there will be a non-zero current showing on the Pfeiffer meter). The pressure regulates at ~ 25% above the setpoint when the gun is off, since the pressure sensor reading changes with the gun comes on.
4. Now you are ready for ion sputtering.
5. The system pressure should be in the low 1e-9 range when not sputtering. It may rise to ~ 1e-8 while sputtering.

Operating Conditions

Max current at condenser 66, Obj 61 for 2 kV.

Recorded current, clean copper sample no bias:

66   3.5 uA

70   2.2

80   0.27

85   0.11

90  0.05

Not much beam shift with Cond, Obj

At 1 kV, center shifts to (-0.5,-0.5) from (-0.9, 0.2), FWHM increases to ~ 1.5

Cond 60 387 nA

62  692

64   950

66  1070

68  860

70  590

75  193

80  65

85  27

Update profile Obj 61 Cond 66

SED Detector How To

1. Start SmartSEM software
2. Turn on SED Control Unit
3. Push Remote button to enable control by SEM
4. In SmartSEM select signal SE2 on main or Dual Channel window
5. Adjust contrast and brightness
1. "contrast" is Channeltron voltage displayed on controller, value depends on beam current. For large currents may be ~ 1500 V, for small currents, may max out at 2500 V.
2. "brightness" is an offset voltage on the SEM signal, for the SED larger brightness makes the image darker. This is the opposite of the In Lens detector.