Diffusion and Segregation of Carbon in SiO2 Films

Diffusion of carbon in SiO 2 films and its segregation at the Si/SiO 2 interface were investigated using carbonincorporated borophosphosilicateglass (BPSG) films and carbon-implanted SiO 2 films. It was found that carbon atoms diffuse in SiO 2 film at a temperature as low as 500°C. Carbon atoms segregated at the Si/SiO 2 interface and induced positive charge. The positive charge density was proportional to the segregated carbon concentration. Field emission transmission electron microscopy (FE-TEM) and electron energy loss spectra (EELS) observations revealed that carbon atoms exist on the SiO 2 side of the interface, and another carbon-rich phase is formed in SiO 2 .