DECONVOLUTION OF NARROW BORON SIMS DEPTH PROFILES IN SI AND SIGE

We present results on deconvolution of molecular beam epitaxy (MBE)-gr own baron profiles in Si and SiGe that are of crucial importance for S i/SiGe heterojunction bipolar transistors (HBTs). They are based an th e assumptions of linearity and homogeneity of the measurement. We dete rmine experimentally the physical limits of these assumptions by inves tigating sequences of boron spikes in Si and SiGe, The deconvolution i s performed by Fourier transformation into the k-domain, preceded by a physically motivated least-squares fitting of the measurement data. I n this way, the high-frequency noise contributions are eliminated to a great extent without producing a systematic broadening. The numerical evaluation of the SIMS profiles is extremely fast in comparison to fo rward techniques and the numerical error is shown to be small, We disc uss the deconvoluted SIMS profiles of MBE-grown boron spikes in Si and SiGe after annealing. Our method is suited to give information about the dopant outdiffusion from th SiGe layer in the case of HBTs.