The generation and characterization of thermally induced defects during Si epitaxy were investigated. To induce thermal slip into test wafers, steep radial and axial temperature gradients were introduced in 150mm-diameter test wafers during the temperature ramp-up in a single wafer reactor. Epitaxial layers were deposited by vapor phase epitaxy at about 1100C using trichlorosilane as a precursor gas. The wafers were characterized using laser light scatter surface maps, atomic force microscopy, X-ray diffraction, double-crystal X-ray topography, and defect etching. Dislocations and stacking faults in densities of up to 5 x 107/cm2 were found inside a distinct ring-shaped pattern on the wafer surface, compared to significantly lower densities (about 102/cm2) outside of the ring pattern region. The distribution of the observed surface light scatter points at the epitaxial layer surface corresponds to the ring-shaped region of thermal slip. In certain cases, the hillocks were not detected using commonly employed detection methods like laser light scattering. The surface features were attributed to the deposition parameters which were used. The detection capability for encountered defects was considered.

Surface and Bulk Characterization of Thermally Induced Defects during Silicon Single Wafer Epitaxy. P.Feichtinger, M.S.Goorsky, F.Muemmler, S.Rickborn, Q.Tran, D.Oster, J.Moreland: Journal of Crystal Growth, 2002, 237-239, 1388-93