Search

Abstract: We present the fabrication and characterization of ultra thin and relatively thick SiGe-On-Insulator wafers with different Ge contents prepared by Ge condensation technique. The fabrication procedures as well as the structural analysis are detailed. The electrical properties of advanced strained SiGe-On-Insulator (SGOI) and relaxed Germanium-On-Insulator (GeOI) wafers were investigated using the Pseudo-MOSFET method and then compared with Silicon-On-Insulator (SOI) and strained Silicon-On-Insulator (sSOI) structures. GeOI wafers with 10-nm and 100-nm film thickness show exceptionally high hole mobility as compared to both SOI and sSOI structures. The hole mobility can reach 400cm2/Vs. It is found that the mobilities for holes and electrons vary in opposite directions as the Ge fraction is increased. The Ge content also impacts the threshold and flat-band voltages. [Copyright &y& Elsevier]

Abstract: We have studied the oxidation of embedded SiGe mesas on SOI in order to co-integrate planar high Ge enriched mesas and Si mesas in the same wafer. We show that oxidation of such structure by local Ge condensation technique leads to non-uniform areas close to mesa sidewalls. Because oxidation kinetic seems to be lowered at a certain point, and since oxidation kinetic is assumed to be stress-dependent, we propose to act on the different sources of strain to counterbalance the difference in oxidation kinetic. In one hand, strain induced by the growth of SiO2 is removed by alternation of SiGe oxidation and SiO2 removal during the whole process. On the other hand, the nitride oxidation mask is deposited with compressive or tensile intrinsic stress to study its influence on the induced strain in the SiGe mesa. We show that by choosing the right value of intrinsic stress in the nitride, uniform SiGe mesa with high Ge content could be achieved. [Copyright &y& Elsevier]

Abstract: The abundance of work on SiGe based devices demonstrates the importance of compositional characterization of such materials. However, SIMS characterization of SiGe layers often suffers from matrix effects due to non-linear variation of ionization yields with Ge content. Moreover, the presence of oxide in these layers would definitely increase the difficulty to obtain quantitative profiles by SIMS. We highlight here the improvements brought by the extended Full Spectrum protocol, presented in previous works and allowing minimization of matrix effects in SiGe matrices compared with more classic protocols. This results in more accurate depth profiles, and thus brings better comprehension of the behavior of intrinsic and doped layers under dry or wet oxidizing. [Copyright &y& Elsevier]

Abstract: The abundance of work on SiGe based devices demonstrates the importance of compositional characterization of such materials. However accurate SIMS depth profiling of SiGe, and especially of SiGe/silicon dioxide interfaces can be difficult due to matrix effects. Therefore, we highlight here the improvements brought by the extended Full Spectrum protocol, presented in previous works and allowing minimization of matrix effects. Previous studies on this protocol showed that it was extremely precise and reproducible for Ge and impurity quantification in non oxidized matrices. In this study we thus investigated its accuracy for simultaneous quantitative depth profiling of both matrix elements (Si, Ge, O) and impurities (C) in Si0.82Ge0.16C0.02 layers annealed in oxidizing atmosphere, by comparing results with more classic protocols. The profiles provided by the extended Full Spectrum protocol were found to be more accurate than the others, especially around interfaces. This results in a better comprehension of the behaviour of SiGeC layers under oxidizing anneal and thus allows the fabrication of very well controlled three dimensional Ge nanowire structures for next generation devices. [Copyright &y& Elsevier]