DEPTH RESOLUTION IN SIMS STUDY OF BORON DELTA-DOPING IN EPITAXIAL SILICON

Microelectronic needs accurate analysis of very thin layers as delta d oped structures. By secondary ion mass spectrometry (SIMS) with O2+ io n beam, we analyse mono-delta of boron in silicon located at 30 nm und er 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 stu dy modifications of the SIMS profiles within the projected range of pr imary ion beam R(p). From the dependence of FWHM within R(p), we deduc e the real thickness of pseudo-delta thin layers by assuming a convolu tion process for SIMS measurements. This assumption is well confirmed by the analysis of a boron tri-delta doped layers.