Properties of nitrogen doped silicon films deposited by low-pressure chemical vapor deposition from silane and ammonia

Abstract

Nitrogen doped silicon ͑NIDOS͒ films have been deposited by low-pressure chemical vapor deposition from silane SiH 4 and ammonia NH 3 at high temperature ͑750°C͒ and the influences of the NH 3 /SiH 4 gas ratio on the films deposition rate, refractive index, stoichiometry, microstructure, electrical conductivity, and thermomechanical stress are studied. The chemical species derived from silylene SiH 2 into the gaseous phase are shown to be responsible for the deposition of NIDOS and/or ͑silicon rich͒ silicon nitride. The competition between these two deposition phenomena leads finally to very high deposition rates ͑Ϸ 100 nm/min͒ for low NH 3 /SiH 4 gas ratio (RϷ0.1). Moreover, complex variations of NIDOS film properties are evidenced and related to the dual behavior of the nitrogen atom into silicon, either n-type substitutional impurity or insulative intersticial impurity, according to the Si-N atomic bound. Finally, the use of NIDOS deposition for the realization of microelectromechanical systems is investigated.

Film properties of nitrogen-doped polycrystalline silicon for advanced gate material

“…In the presence of NH 3 , NH 3 reacts with SiH 4 to form silylamine (SiH 3 NH 2 ) and hydrogen gas [9]. As the amount of NH 3 is increased, the concentration of hydrogen in the gas phase increases.…”

Properties of non‐stoichiometric nitrogen doped LPCVD silicon thin films

“…The deposition temperature T and the total pressure P were, respectively, fixed to 465 °C and 200 mTorr. The nitrogen ratio x =N/Si was measured by ellipsometry using a simple relationship between the NIDOS film refractive index and its ratio developed in ____________________ © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.crt-journal.org previous works [8,9]. These values are compared to those deduced using EDX analysis.…”

“…Indeed, the nitrogen atoms can effectively act as an n-type impurity in silicon. However, its doping properties cannot be compared with those of the usual n-type impurities, like phosphorus or arsenic, due to the low solubility and diffusivity of nitrogen atoms in silicon [9]. For nitrogen content higher than 8%, resistivity increases drastically, highlighting that the electrical properties of NIDOS films depend significantly on morphological properties rather than on the nitrogen content.…”

“…For this reason, nitrogen doped silicon films found a various application not only in microelectronic systems, but also in optical filter fabrication [5,6] and microelectromechanical devices [4]. In the bilayer structure of CMOS polysilicon gate, nitrogen level doping must be carefully optimized because of the aptitude of this impurity to the non-suitable increase of the total resistance of the gate [7][8][9]. In this work, we are interesting to the study of the non-stoichiometric in-situ nitrogen doped silicon (NIDOS) films obtained by LPCVD at low deposition temperature.…”

Use of a neural network to characterize the charge density of PECVD-silicon nitride films

“…The plasmaenhanced chemical vapor deposition (PECVD) system has been widely used to deposit SiN films [1][2][3][4][5][6]. The SiN films were deposited in SiH 4 -NH 3 [1,2] or SiH 4 -N 2 [3] plasma. Apart from the SiN films, plasma-driven processes are widely used to deposit or etch a variety of films [4][5][6].…”