HIGH-TEMPERATURE STABILITY OF HETEROEPITAXIAL IR-SILICIDE SIGE LAYERSCO-DEPOSITED ON SI(100) UNDER ULTRA-HIGH-VACUUM/

Heteroepitaxial Ir-silicide/SiGe layers have been grown on top of p-Si (100) at a substrate temperature of 450 degrees C under ultra-high vac uum. The epitaxial Ir-silicide layer was determined to be Ir3Si4 with four types of epitaxial modes. Reflection high-energy electron diffrac tion was used to examine the film quality. The high-temperature stabil ity of the epitaxial Ir3Si4/SiGe layers was investigated by rapid ther mal annealing the Ir3Si4/SiGe layers at 550, 750 and 950 degrees C for 20 s. The chemical composition, microstructures and surface morpholog ies of the layers were characterized by using Auger electron spectrosc opy, grazing angle incidence X-ray diffraction, scanning electron micr oscopy and cross-sectional transmission electron microscopy. A critica l transition temperature existed between 550 and 750 degrees C for the Ir3Si4/SiGe layers, beyond which the Ir3Si4/SiGe layers were unstable during the rapid thermal annealing process. The Ir3Si4 layer became a mixture of dual Ir-silicide phases containing Ge atoms as the instabi lity occurred. Because of the thermal instability, the conventional gu ard-ring fabrication should be performed before deposition of epitaxia l films.