The technology for analyzing the conditions of rapid thermal annealing by optical second harmonic generation

Abstract

Optical second harmonic generation (SHG) has been used to analyze the ULSI process, including low energy ion-implantation and rapid thermal annealing (RTA). The projected range of the low energy ion-implantation is approximately 20 nm, which results in a region that is transformed into an amorphous state by high dose ion-implantation, and the surface layer region is recrystallized during RTA process. The symmetrical point group of the Si (1 1 1) surface layer is 3 mm, which differs from that of centrosymmetric bulk Si which has no dipole contribution. The reflected SHG (RSHG) of the Si (1 1 1) is contributed mainly from the surface dipole and surface quadrupole. A plot of RSHG versus azimuthal angle reveals information on the recrystallization of amorphous silicon during RTA. The optimization of RTA step is determined by RSHG, which is shown to be suitable for analyzing the ULSI process.