Journal of the electrochemical society vol:151 issue:11 pages:F269-F275
The quality of HfO2 dielectric layers was systematically evaluated using wet etching monitored by open-circuit potential analysis. Scanning electron microscopy imaging was used to observe changes in the topography after etching. Our results showed that surface pretreatment prior to high-k deposition, as well as postdeposition treatments, have an effect on the quality of the high-k material as seen from the etch behavior of these materials. The wet etch defect monitoring was subsequently used to improve the quality of the high-k films. As-deposited films may have a high defect density of 1.10(9) wet-etch defects/cm(2). However, after appropriate postdeposition annealing, high-k layers with reduced defect density can be obtained. A lower defect density can also be correlated to improved electrical properties of the high-k layer. The presence of defects is speculated as being due to crystallization phenomena and/or an oxygen-deficient HfO2 film, evidenced by Si/SiO up-diffusion upon thermal treatment. (C) 2004 The Electrochemical Society.