Dislocation dynamics of silicon-germanium relaxation on silicon-on-insulator substrates

SiGe alloy films and silicon-on-insulator (SOI) substrates have gained recent acceptance in semiconductor manufacturing for high-speed electronic devices. This thesis examines the growth and relaxation of SiGe films on SOI substrates.; Sample temperature measurements are often highly inaccurate. A pyrometry system was developed to measure the sample emissivity in situ, greatly improving sample temperature measurement accuracy. The emissivity of the SOI substrate was measured to vary by up to 300% during film growth and the real sample temperature fluctuated by up to 65°C (or 12.5%). This real sample temperature change results from the dependence of the sample radiative cooling efficiency with emissivity. An in situ emissivity measurement is necessary to maintain a constant sample temperature during film growth on SOI substrates.; The relaxation of Si_0.82Ge_0.18 films on SOI substrates was investigated by annealing metastable films and through film growth beyond the critical thickness for dislocation formation. Different SOI substrates were used, having a top silicon layer thickness between 40 nm and 10 μm. SiGe film relaxation was found to occur via the nucleation and propagation of dislocations with the same onset and rate of film relaxation on SOI substrates and on bulk Si. Surface crosshatch developed as a result of dislocation motion in the SiGe film. Strain developed in the top Si layer of the SOI substrate following film relaxation, and is the product of threading dislocation motion in the layer.; The buried amorphous oxide relaxes the dislocation strain field and removes the dislocation line tension. This change in line tension drives threading dislocation motion and the development of strain in the thin Si layer of the SOI substrate, which is accurately modeled by an equilibrium strain calculation. The buried amorphous layer allows threading dislocation motion and strain relaxation without forming a misfit dislocation and therefore without a critical thickness. This is a fundamental change from the existing understanding of film relaxation, and while similar to compliant substrate relaxation is based on threading dislocation motion.; This dislocation model is important for understanding dislocation dynamics on SOI substrates and related systems having a buried amorphous layer.