Organic Grafting on Si for Interfacial SiO2 Growth Inhibition During Chemical Vapor Deposition of HfO2
Résumé
Engineering of the silicon/high-permittivity (high-kappa) dielectric interface by grafting an ultrathin organic layer on the silicon surface before HfO2 deposition is explored. Si(111) and Si(100) surfaces are functionalized using methyl groups as well as long alkoxy and functionalized alkyl chains. Amorphous HfO2 films are deposited by metal organic. chemical vapor deposition. We show that methyl or carboxydecyl groups efficiently inhibit the formation of SiO2, while the quality of the HfO2 layer (uniformity, permittivity) is not affected by the grafting. The flatband voltage in metal-oxide-semiconductor structures with films grown on methyl grafted p-type Si(100) is shifted by an additional similar to 100 to 300 mV compared to that with films grown on a chemical SiO2 oxide. This is in good agreement with the expected dipole effect related to the grafting of such molecules on silicon. The interfacial state density is comparable to the one measured on films grown on SiO2/Si. This study opens up the route for the engineering of the Si/high-kappa oxide interface using organic grafting.