3 Product and Functional Description | 3.2 Main Components
ZEISS
1
2
4
5
6
7
9
11
12
13
14
16
10
3
8
17
15
18
Fig. 12: Schematics of the vacuum system in HV mode
1
Gun with filament
2
Gun head
3
Multihole aperture (Gemini I column),
single hole aperture (Gemini II column)
4
Column chamber valve
5
Bypass
6
Specimen chamber
7
Vent valve, flanged to TIV
8
Turbo isolation valve (TIV)
9
Turbo pump
10
Ion getter pumps (IGP)
11
Gas flow valve (GFV)
12
Pirani gauge
13
Penning gauge
14
Vent valve
15
Roughing backing valve (RBV)
16
Pre-vacuum pump
17
Pre-vacuum separation valve (PVS)
18
Buffer tank for optional Quiet Mode
Function
In HV mode, the pre-vacuum pump
16
and the turbo pump
9
evacuate the specimen
chamber
6
. The pre-vacuum separation valve (PVS)
17
has opened the connection between
pre-vacuum pump and turbo pump. The turbo isolation valve (TIV)
8
is open.
The vacuum in the specimen chamber is measured by a Penning gauge
13
. The detected vac-
uum values are displayed as
System vacuum
in the SmartSEM user interface. As long as the de-
tected pressure in the specimen chamber is not ready for operation, the column chamber valve
4
is closed in order to separate the specimen chamber from the column.
When changing to HV mode, the acceleration voltage decreases to zero and the column chamber
valve closes. The GFV closes and as soon as the chamber pressure drops below the minimum
chamber pressure (MCP = 15 Pa) the RBV closes and the TIV opens. If the beamsleeve is in, the
stage is lowered by 20 mm and the beamsleeve is retracted. If not, the beamsleeve stays out.
Then the column chamber valve opens and the acceleration voltage is turned on again.
30
Instruction Manual ZEISS GeminiSEM series | en-US | Rev. 2 | 349500-8138-000
