Published: 07 July 2015

Ion Beam Centre’s research to feature in Royal Society of Chemistry collection

Julien Colaux and Chris Jeynes of the University of Surrey’s Ion Beam Centre have been invited to include their paper ‘Certified ion implantation fluence by high accuracy RBS in the Analytical

The paper demonstrates that the classical method of Rutherford backscattering spectrometry (RBS) really can be used as a primary direct reference method for measuring Quantity of Material in thin films. The method is reference-free,  and makes no assumptions about the sample,  that is,  it is self-validating.  RBS is “non-destructive”,  that is,  the sample is not significantly changed unless the energy deposited by the beam causes changes (such as cross-linking in polymers or other beam-damage effects).

The Ion Beam Centre is a world leader in ion implantation research:  ion implantation is an enabling technology for the huge semiconductor industry world-wide.  This work summarises the quality assurance method we use for certifying the implantation fluence,  obtaining absolute accuracies approaching 1%.  This is done directly for test implants,  without the system calibration required for industrial implanters.

The work depends on accurate determination of the electronic gain of the spectrometric system (Analytical Methods 2015) and of the energy loss behaviour of silicon (which is used as an internal reference: Analytical Methods 2014).  The robustness of the method was first demonstrated in a multi-lab comparison (Analytical Chemistry 2012: Surrey, Budapest, Lisbon).

The beam energy is also obtained directly with very high accuracy,  enabling absolute calibration of the terminal voltage of the accelerator (Nuclear Instruments & Methods B, 2015).  This was also a multi-lab work (Surrey, Namur) which incidentally established the energy of the 7156 keV level of the  20Ne nucleus with a greatly reduced uncertainty.

In addition, the method is currently undergoing accreditation for ISO 17025 certification, which would be a first for any Ion Beam Analysis lab worldwide.

The work is the culmination of a series of five papers:

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