Depth Resolution In Sims Study Of Boron Delta-Doping In Epitaxial Silicon

Microelectronic needs accurate analysis of very thin layers as delta doped structures. By secondary ion mass spectrometry (SIMS) with O2+ ion beam, we analyse mono-delta of boron in silicon located at 30 nm under the surface and then a multi-delta of boron in silicon located just under the surface (almost-equal-to 10 nm). For the mono-delta, we study modifications of the SIMS profiles within the projected range of primary ion beam R(p). From the dependence of FWHM within R(p), we deduce the real thickness of pseudo-delta thin layers by assuming a convolution process for SIMS measurements. This assumption is well confirmed by the analysis of a boron tri-delta doped layers.