Influence of induced stress on enrichment kinetic during local Ge condensation of SiGe/SOI mesas

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.