STRAIN RELAXATION IN EPITAXIAL SI1-XGEX LAYERS DURING SOME SILICIDATION PROCESSES

Strain relaxation in Si1-xGex epitaxial layers is investigated after t he reaction of Co and Pt with strained SiGe alloy. The epitiaxial SiGe alloy studied has a Ge fraction ranging between x = 5% to 22%. The st rain in the Si1-xGex is evaluated using multi-crystal high resolution x-ray diffraction mapping in reciprocal space (MC-HRXRD). The results show that for Co in order to keep the strain in Si1-xGex unaffected, a sacrificial Si layer is needed. The direct reaction of 40nm Co on Si0 .9Ge0.1 can lead to defect formation and 40% strain relaxation. This i s in contrast to Pt/S1-xGex reaction, where negligible relaxation was observed.