Boron Precipitation and misfit dislocation structure in Si(Ge,B) buried epitaxial layers

Heavily boron-doped silicon buried epitaxial layers are becoming increasingly important in the fabrication of thin membranes, three dimensional structures in silicon and latch-up free CMOS circuits. Si(Ge,B) co-doping has been utilized to compensate the B-induced lattice contraction in Si and hence buried high conducting layers which are strain-free and lattice matched to the Si substrate have been realized. The utilization of isoelectronic Ge also alters the point defect distribution in silicon resulting in reduced dopant diffusion which is an added advantage in realizing shallow junctions and reduced interfacial transition width in epitaxial layers. This contribution addresses the evolution of misfit dislocation structure and B precipitation behavior in heavily B-doped buried Si epitaxial layers. In addition, the effect of Ge co-doping on B solubility in Si will be discussed.Silicon epitaxial layers were grown at 1080°C by chemical vapor deposition on 4-inch diameter p-type (100) substrates (10 and 0.04 Ω-cm) employing the SiH2Cl2-B2H6-GeH4-H2 chemical system. Single 5 μm thick epilayers and 2 μm buried layers with 4 μm intrinsic cap layers (10 Ω-cm) were grown.