La 2O 3 gate insulators prepared by atomic layer deposition: Optimal growth conditions and MgO/La 2O 3 stacks for improved metal-oxide-semiconductor characteristics

Takuya Suzuki, Miyuki Kouda, Parhat Ahmet, Hiroshi Iwai, Kuniyuki Kakushima, Tetsuji Yasuda*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The authors investigated the optimal growth conditions for atomic layer deposition of La 2O 3 using tris(iso-propylcyclopentadienyl) lanthanum, La( iPrCp) 3, and H 2O, and identified two necessary conditions for achieving self-limiting growth: A low growth temperature (T s) of 150°C-175°C and an extremely long purging after the H 2O feed. Low T s was also preferable for improving the electrical properties of the metal-oxide-semiconductor devices such as the dielectric constant (k), leakage current, and effective mobility. As for the H 2O feed time, a long feed resulted in increased interface-trap density, while a short feed resulted in increased leakage. An H 2-plasma treatment inserted after the thin-La 2O 3 (0.5 nm) film growth reduced the leakage current by 3 orders of magnitude compared to the control sample. An MgO capping on the La 2O 3 remarkably increased the effective k value; however, it degraded the effective mobility. Transmission electron microscopy indicated that the k-value improvement by the MgO capping is due to suppression of La-silicate formation.

Original languageEnglish
Article number051507
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Issue number5
StatePublished - Sep 2012

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