From the IMSA-100 system to the IMSA-Orsay-Physics-FIB

Introduction

 
  This FIB system has been designed to achieve current densities of more than 10 A/cm2. The ion optical column consists of an LMIS, two electrostatic lenses, a pre-lens octupole double deflector, the E*B mass separation system, beam blanker, two stigmators, and a secondary electron/ion detector for imaging. The upper (objective) lens accelerates the ions from the ion source extraction energy of about 7 keV to the final kinetic energy, adjustable between 25 and 50 keV for single charged ions. The lower (projective) lens is an asymmetrical einzel lens. The source is placed in the object-side focal plane of the objective lens and the target plane corresponds with the image-side focal plane of the projective lens. Thus the beam is collimated between the two lenses and a cross-over does not exist which minimizes the beam broadening due to Coulomb-interaction.

After a 12 year operation of the IMSA-100 instrument the system is modernized, because of the beam parameters (spot size of about 200 nm) are not further sufficient for modern tasks in science and technology. The ionoptical column including  supply and computer control is replaced by a CANION 31Z system containing also a mass filter from Orsay Physics (France). Most of the usefull features of the IMSA are still available. The parameters of the new system are summerized in the following table.
 
 

Parameters of the  IMSA-Orsay-Physics-FIB

Energy range 10 - 30 keV (single charged)
Ion Species Ga, Co, Nd, Ge, Au, Si, Er, Ni, Fe, Cr, B, In ....
Current 0.001 - 22 nA
Spot size 14 nm (Ga)
Current density > 20 A/cm2
Mass resolution 35
Samples wafers: up to 6inch 
masks: up to 7 inch
Options
  • special holder for experimental samples
  • heating target holder up to 500oC, 2inch
  • in-situ electrical contacting, 5pins
  • tilding (rotation) 360° inc. 0.28°
  • FIB assisted etching
  • FIB assisted deposition (W)
  • charge neutralisation
Stage laser interferometer controlled x-y stage 
160 x 160 mm2
accuracy: <  50 nm
Scanfield max 500 x 500 µm2  (depending on energy)
for larger patterns: stitching possible
Data input format ASCII, AutoCAD
Imaging and 
Surface Analysis
  • secondary electron detection
  • current induced imaging
  • ion beam induced acoustic wave detection 
  • in-situ CCD camera
  • two measuring channels for optical methods, i.e. ellipsometry

 

Performance of a FIB system

An important property of a FIB system is the beam intensity distribution, which is given here for Co and Ga ions obtained with the IMSA-100 instrument.

Publications