SEM Gun/Aperture/Stig Realign - Jan 2017

Mechanical align shown in previous post, here is optical/electrical done at 3 kV

Aperture plate at 3 kV Max settings

Center aperture 60 um #1

1. Used for MAX, 200 and 100 pA
2. Shift gun align onto aperture, must adjust aperture to compensate when emission image vanishes.
3. Gun -2.5, -54.5%, App +2.0, +63.4, tweak gun to maximize current in spot mode image center.
4. On 10 um grid rough focus with aperture align, enough to see grid squares 10 um. 
5. Leave stig zero for now, fix on Au/hopg

Max current align #1 60 um
Green text is wrong, Gun -2.5, -54.5, App +4.0, +61.4, WD 9.24

120 um #6

1. 1.5 to 3 nA settings
2. Gun -53.0, -65.5 App +61.0, +71.5, WD 9.30 
3. To get rough aperture align, do gun align, then find min and max aperture values to illuminate without clipping (one axis at a time) then pick average. 

120 um #6,
(image is mis-labeled, originally confused 120 and 90)

90 um #5

1. 0.6 to 1.0 nA settings
2. Gun +8.6, -6.7 App -8.3, +11.9, WD 9.17

90 um

75 um #4

1. 400 pA setting only
2. Gun +31.0, -92.5 Aperture -33.5, +98.0, WD 9.48

75 um

30 um #3

1. 40 to 80 pA
2. Gun 45.5, -45.2 App -49.0, +51.4 WD 9.42

30 um

20 um #2

1. used for 20 pA only
2. Cannot align, out of range

20 um, out of range of gun and aperture alignment