Operating parameters for Argon-ion-gun

Controller for Argon-ion gun, used for cleaning sample prior to deposition and for etching.

Several trials have been made to find out optimum settings for etching with the gun.
Pieces of Si-wafers were used for testing. Each piece was covered with about 50 nm of aluminum with the e-gun.

For reasonable etch-rate and maximum area coverage settings should be:

Beam energy [kV]	Emission [mA]	Scan voltage Area1	Focus	Deflection	Pressure [mBar]
3	30	3 (max)	min (7 o'clock)	X=center, Y=near max	1.6×10-6

Optimum settings of controller for good etch-rate and maximum area coverage,
focus at minimum,
X-deflection at center,
Y-deflection at near maximum.

On the vertical transfer rod there is a marker, angle indicator.
For correct direction towards Ar-ion-gun, set to 150 degrees.
For correct direction towards e-gun, for deposition, set to 0 degrees.

Marks on sample holder, one at the top for reference to mount sample holder always with this mark upwards.
One area near center indicating area of good etching at above settings.

Measurements for different settings

Scan voltage Area1	Focus	Pressure [mBar]	Etch depth [nm]					Deposited Alu. [nm]
0	minimum	7×10-7	85	117	125	144	75	50	53	53
0.5	minimum	7×10-7	70-80	63-77	53-67			40	45	42
1.5	minimum	1.6×10-6	33-103	39-105	59-62	94-116	81-101	55	56	52
3	minimum	1.6×10-6	40-50	27	42	35	30	40	37	42
3	12 o'clock	1.6×10-6	3	4	2	2		45	49	44