Effects of Film Thickness and Preferred Orientation on the Dieletric Constants of Hf-Aluminate Films Deposited by PEALD

Abstract

The thickness changes in Hf aluminate films deposited by PEALD were investigated by modifying the process sequence. The conventional supercycle of Hf aluminate film is composed of two groups of subcycles allocated to deposit Al 2 O 3 and HfO 2 films. The dielectric constants of these thin films decrease with decreasing film thickness. This decrease originates to a changing preferred orientation from (200) to (111). Using the modified supercycle which has a periodically addition of small dose of Al 2 O 3 in HfO 2 thin film, the HfO 2 film was transformed from (111) preferred orientation to (200) preferred orientation. As a result of preferred orientation change, the dielectric constant of films increased up to 22.5

Electrical Enhancement and Higher-K Engineering in Ultra-Thin Atomic Layer Deposited Hf1-xAlxOyFilms

“…20 In this regard Moon et al have reported on dielectric constant enhancement with Al 2 O 3 addition in HfO 2 for films deposited by plasma enhanced ALD. 21 However the film thickness studied was thicker than what is required for scaled MOS applications and they observed a decrease in the k-value with decreasing film thickness.…”