Atomic layer deposition analysis of HfSiO4 by mass spectroscopy and XPS

In order to understand the ALD reaction of HfCl4 and (C4H9O)4Si (tetrabutyl orthosilicate, TBOS) for deposition of HfSiO4, in-situ gas analysis of the process chamber was performed by using mass spectroscopy. Due to the complexity of the mass spectral data, it was not possible to identify all of the byproducts of the ALD reaction. However, the results do indicate that the principal reaction pathways result in the formation of HCl, butylene, and other chloroalkanes. The major reaction channel is thought to be formation of butylene: HfCl4 + (C4H9O)4Si → HfSiO4 + C4H8 + HCl. From the XPS measurement, film with very low carbon and chlorine content could be obtained.