Electrical characteristics of an ultrathin (1.6 nm) TaOxNy gate dielectric

Abstract

This letter describes a process for the preparation of high-quality tantalum oxynitride (TaOxNy) via NH3 annealing of Ta2O5, for use in gate dielectric applications. Compared with tantalum oxide (Ta2O5), a significant improvement in the dielectric constant was obtained by the NH3 treatment. In addition, light reoxidation in a wet ambient at 450 °C resulted in a significantly reduced leakage current. We confirmed nitrogen incorporation in the tantalum oxynitride (TaOxNy) by Auger electron spectroscopy. By optimizing the nitridation and reoxidation processes, we obtained an equivalent oxide thickness as thin as 1.6 nm and a leakage current of less than 10 mA/cm2 at −1.5 V.

Analytical TEM characterization of the interfacial layer between ALD HfO2 film and silicon substrate

“…Advanced gate dielectrics have recently attracted large attention due to the need to replace SiO 2 for the further shrinkage of complementary metal-oxide-semiconductor (CMOS) devices [1][2][3]. HfO 2 is one of the best potential candidates due to its high permittivity, chemical inertness to the Si surface and wide band gap.…”

Conduction mechanisms and reliability of thermal Ta2O5–Si structures and the effect of the gate electrode

“…The electrical characteristics and conduction mechanisms in these films in dependence on the gate material also are not very well understood even though extensive studies on the dielectric and structural properties have been done. [3][4][5][6]8,12,15,16 This paper reports a systematic investigation of the effect of the gate electrode material on the oxide characteristics, conduction mechanisms, and dielectric strength of thermal Ta 2 O 5 on Si. A study of the reliability behavior of MOS capacitors with thermal Ta 2 O 5 is also performed and the attention is focused on the charge trapping and trap generation in the dielectric stack ͑Ta 2 O 5 -SiO 2 ͒ during a constant current stress ͑CCS͒.…”

“…[3][4][5][6][7] One of the unresolved problems of Ta 2 O 5 ͑which is typical of many high-k dielectrics͒ is the unavoidable formation of an interfacial SiO 2 layer which minimizes the interface state density and reduces the intermixing of Si and Ta 2 O 5 , but at the same time it decreases the global dielectric constant of the film. As a result, the obtained dielectric constant is not adequate to reach an equivalent dielectric thickness of less than 2 nm with an acceptable leakage current level.…”

Improved electrical properties of Ge metal-oxide-semiconductor capacitor with HfTa-based gate dielectric by using TaOxNy interlayer

“…Since TaO x N y has a high k value ͑ϳ26͒ and high thermal stability, 9 it should also be a promising candidate as the interlayer between high-k dielectric and Ge substrate. In this work, a thin TaN x layer is deposited by reactive sputtering prior to HfTa-based oxide or oxynitride deposition.…”