THERMAL STABILITY INVESTIGATIONS OF PECVD Al2O3 FILMS DISCUSSING A POSSIBILITY OF IMPROVING SURFACE PASSIVATION BY RE-HYDROGENATION AFTER HIGH TEMPERATURE PROCESSES

摘要

This work investigates the changing passivation behavior of Al_2O_3 after different thermal treatments based on carrier lifetime (τ_(eff)), interface defect density (D_(it)) and fixed charge density (Q_(tot)) measurements. A concept of diffusing H species into the dehydrogenated Al_2O_3 films, termed as re-hydrogenation, has also been investigated for the PECVD deposited Al_2O_3 samples. Use of a-SiN_x:H as a capping layer as in Al_2O_3/a-SiN_x:H stack provides a better thermal stability for a thin PECVD Al_2O_3 layer. A comparison between single Al_2O_3 layer and Al_2O_3/ a-SiN_x:H passivation stack after high temperature processes has been also performed in this work.