1. Formation of interfacial layer during reactive sputtering of hafnium oxide.
- Author
-
Tsui, Bing-Yue and Chang, Hsiu-Wei
- Subjects
- *
HAFNIUM oxide , *SPUTTERING (Physics) , *INTERFACES (Physical sciences) - Abstract
Hafnium oxide is one of the most promising high dielectric constant materials to replace silicon dioxide as the gate dielectric. To take the advantages of high dielectric constant of HfO[SUB2] thoroughly, the relatively low dielectric constant interfacial layer must be controlled carefully. In this work, the formation of an interfacial SiO[SUB2] layer at the HfO[SUB2]/Si interface was studied comprehensively. It is observed that during reactive sputtering deposition of the HfO[SUB2] layer, a very thick interfacial SiO[SUB2] layer, thicker than 3 nm, would be grown. O-radical signals, instead of O[SUB2]-radicl signals, are detected in the sputtering chamber. An O-radical enhanced oxidation model is proposed to explain such an unusual thick SiO[SUB2] layer. The adoption of a two-step deposition method, the thickness of interfacial SiO[SUB2] layer can be reduced only if the bottom Hf layer is thicker than 5 nm. However, the reduction of effective oxide thickness would be limited. Reoxidation of Hf film sounds a better choice. A 1.0-1.5-nm-thick interfacial SiO[SUB2] layer is still observed. This implies that the traced oxygen in the sputtering chamber plays a critical role on the formation of the interfacial layer. It is thus concluded that reactive sputtering is not a suitable method to prepare a HfO[SUB2] layer with a negligible interfacial SiO[SUB2] layer. Reoxidation of Hf film is a better choice, but the oxygen content in the sputtering chamber must be well controlled. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF