High crystalline quality of SiGe fin fabrication with Si-rich composition area using replacement fin processing

A high crystalline quality of SiGe fin with an Si-rich composition area using the replacement fin processing is systematically demonstrated in this paper. The fin replacement process based on a standard FinFET process is developed. A width of less than 20-nm SiGe fin without obvious defect impact both in the direction across the fin and in the direction along the fin is verified by using the high angle annular dark field scanning transmission electron microscopy and the scanning moiré fringe imaging technique. Moreover, the SiGe composition is inhomogenous in the width of the fin. This is induced by the formation of 111 facets. Due to the atomic density of the 111 facets being higher, the epitaxial growth in the direction perpendicular to these facets is slower than in the direction perpendicular to 001. The Ge incorporation is then higher on the 111 facets than on the 001 facets. So, an Si-rich area is observed in the central area and on the bottom of SiGe fin.