THERMAL AND EXCIMER-LASER ASSISTED GROWTH OF SI(1-X)GEX ALLOYS FROM SI2H6 AND GEH4 MONITORED BY ON LINE SINGLE-WAVELENGTH ELLIPSOMETRY AND EX-SITU ATOMIC-FORCE MICROSCOPY

Single wavelength ellipsometry was used to monitor the growth of Si(1- x)Ge-x alloys obtained by ultrahigh vacuum chemical vapor deposition ( CVD) at 570 degrees C on Si and to evaluate the effect of sample irrad iation by KrF excimer laser pulses at an energy density above the thre shold far surface melting. Laser irradiation was performed during or a fter the CVD growth. When the Si(1-x)Ge-x alloys were grown without la ser assistance, the recorded ellipsometric curves indicated the presen ce of pronounced surface roughness, which was confirmed by atomic forc e microscopy analysis. On line ellipsometry during multiple pulse post growth irradiations showed a sudden increase of the ellipsometric angl es Psi and Delta corresponding to the first laser pulse. This behavior attested to the smoothing of the surface microroughness induced by th e melt-recrystallization cycle. The excimer laser assisted CVD growth of Si(1-x)Ge-x alloy layers was also followed. By changing the ratio b etween the thermal growth rate and the irradiation frequency the kinet ics of surface roughening was studied. (C) 1998 American Vacuum Societ y.