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