Recystallization characteristics of polycrystalline silicon films amorphized by germanium ion implantation

Abstract

The recrystallization characteristics of polycrystalline silicon (poly-Si) films amorphized by germanium ion (Ge +) implantation on a SiO 2 layer are studied by TEM analysis, and the possibility of enlarging the final grain size is investigated. Also, the characteristics of Ge + implanted films with phosphorus doping are reported and discussed. The nucleation and growth rates of undoped Ge + implanted films are lower and higher, respectively, than those of silicon ion (Si +) implanted films, so that the former films achieve grain sizes about 2–3 times larger than the latter films, depending on annealing temperature. Phosphorus doping in Ge + implanted films effectively enhances the grain size, because of the retardation of random nucleation and the enhancement of grain growth. An average grain size of 12 μm is obtained in doped Ge + implanted films with a phosphorus concentration of 1 × 10 20 ions/cm 3 after annealing at 650°C for 5 h, which is about four times larger than that in undoped Ge + implanted films.