Exact compositional analysis of SiGe alloys by matrix effect compensated MCs⁺-SIMS

Abstract

SiGe alloy, owing to its high electron and hole mobility, has potential applications in high-speed microelectronic device technology. The optimization of such technology requires the precise determination of Ge concentration in the full range of composition and the understanding and control of the Ge–Si interdiffusion phenomenon. The most appropriate analytical technique with highest detection sensitivity (∼subparts per billion) for measuring elemental concentration is Secondary Ion Mass Spectrometry (SIMS). However, strong compositional dependence of secondary ion yield, i.e. “matrix effect,” has always made SIMS quantification extremely difficult. A procedure for the accurate quantification of Ge concentration in Molecular Beam Epitaxy (MBE)-grown Si_1−xGe_x (0 < x < 0.72) alloys based on MCs⁺-SIMS approach has been proposed. The “matrix effect” is shown to be completely suppressed for all Ge concentrations irrespective of impact Cs⁺ ion energies. The novel methodology has successfully been applied for direct quantitative composition analysis of Si/Ge multilayer structure.