Recrystallization of amorphized polycrystalline silicon films on SiO2: Temperature dependence of the crystallization parameters

Abstract

This paper presents a theoretical and experimental study of the recrystallization behavior of polycrystalline silicon films amorphized by self-implantation. The crystallization behavior was found to be similar to the crystallization behavior of films deposited in the amorphous state, as reported in the literature; however, a transient time was observed, during which negligible crystallization occurs. The films were prepared by low-pressure chemical vapor deposition onto thermally oxidized silicon wafers and amorphized by implantation of silicon ions. The transient time, nucleation rate, and characteristic crystallization time were determined from the crystalline fraction and density of grains in partially recrystallized samples for anneal temperatures from 580 to 640 °C. The growth velocity was calculated from the nucleation rate and crystallization time and is lower than values in the literature for films deposited in the amorphous state. The final grain size, as calculated from the crystallization parameters, is 2.5 μm for an anneal temperature of 580 °C and 1.5 μm for an anneal temperature of 640 °C and is in agreement with transmission electron microscopy dark-field images of completely recrystallized samples that show grain sizes of approximately 1–2 μm.