Interactions of moisture and organic contaminants with SiO2 and ZrO2 gate dielectric films

Zirconium oxide (ZrO2) is a promising candidate for future high-k gate dielectric applications. Atmospheric molecular contaminants may impact the quality and performance of zirconium oxide thin films. The interaction of moisture and organics (in particular IPA) as common interfacial contaminants with a 5 nm ZrO2 film deposited by ALCVD™ is investigated using atmospheric pressure ionization mass spectrometry (APIMS); the kinetics and mechanism are compared to that of silicon oxide (SiO2). The ZrO2 surface was found to have a higher affinity for moisture and IPA than SiO2. Under similar conditions, the amounts of moisture and IPA adsorbed on ZrO2 were comparatively greater and more temperature sensitive than on SiO2. ZrO2 films also retained a significant amount of moisture that could prove detrimental during subsequent thermal processing. At high temperatures, ZrO2 was found to catalyze decomposition of IPA. IPA adsorption on SiO2 was increased by pre-adsorbed moisture and it led to the formation of alkoxy groups at elevated temperatures. On the other hand, adsorption on ZrO2 was site limited; consequently, less IPA was adsorbed in presence of pre-adsorbed moisture.