Comparison of a new simple system for high depth resolution RBS with the magnetic spectrometer

With decreasing layer thicknesses e.g. in semi-conductor devices, there is a strong need for increasing depth resolution in analytical methods used for the determination of elemental depth profiles. Standard RBS using Si detectors has a depth resolution of about 5 – 15 nm mainly depending on incidence angle and energy resolution. The traditional and high-tech solution is to use a magnetic spectrometer or a time-of-flight system to improve the energy resolution of the detector and thus the depth resolution.
At HZDR, a Browne-Buechner type magnetic spectrometer is available for high depth resolution measu¬rements with sub-nm depth resolution in a near-surface region  5 nm. However, such a system is expensive and requires complicated operation. In addi¬tion, the small energy window of the magnetic spectrometer limits the measurement to one element and about 10 nm depth range. Currently we are implementing a low-tech detection system that uses improvements in amplifiers and cooling to improve the energy resolution of standard semiconductor detectors to sub-10 keV values. The capabilities of such a system are described and compared to the magnetic spectrometer.