Beam Flux Monitor

Beam Flux Monitor

The Beam Flux Monitor (BFM) is designed to measure the beam equivalent pressure (BEP) of the atomic/molecular beam emitted by a source in a UHV process chamber.  

The BFM is mounted just below substrate level so that the ionization gauge (IG) can be positioned directly beneath the substrate for measurement.  

Application: 

The BEP can be used to calibrate the flux for each source (e.g., effusion cell) and determine a suitable flux ratio for growth.  

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Product overview

The Beam Flux Monitor includes: 

  • Bayard-Alpert type nude ionization gauge head – with twin-tungsten filament for improved durability and thermal stability 
  • UHV sealed bellows assembly with linear motion,  
  • Stepper motor with mounting adapter and clutch (optional) 

In the idle state the BFM may be retracted to the following positions:  

  1. behind a tantalum shield  
  2. behind the chamber cryopanel 
  3. behind an isolation gate valve 

 

The length of the linear motion is therefore dependent on the process chamber diameter and the idle position.   

Special Add-on Feature  

 To maximise the system up-time and minimize disruption to growth campaigns, the BFM may be isolated vacuum-wise from the process chamber. This allows quick exchange the IG head without venting the main process chamber.  Ideal for production systems and busy research labs! 

Specifications

Mounting flange DN63CF
Linear travel (mm)  150 – 500 mm 
Bakeout temperature  200 °C
Pressure sensitivity 1E-4 … 5 E -11 Torr
Filament Tungsten (recommended) Thoriated iridium
Motion Interlock  Position sensor included 
Motorized control  Optional (requires MCU-BFM)
Gate valved isolation  Optional

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