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DC reactively sputtered ­TiNx thin films for capacitor electrodes Nana Sun1 · Jin Xu2 · Dayu Zhou1 · Peng Zhao1 · Shuaidong Li1 · Jingjing Wang1 · Shichao Chu1 · Faizan Ali1 Received: 9 February 2018 / Accepted: 5 April 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018

Abstract Being used as typical electrode layers in the state-of-the-art microelectronic devices, titanium nitride (­ TiNx) thin films have to meet the critical requirements for high conductivity, low surface roughness and thickness. In this work, ­TiNx thin films were deposited by direct current (DC) reactive sputtering in a nitrogen and argon ambient using a titanium target. Upon systematically adjusting the sputtering current, target-substrate distance and deposition time, the evolution of film properties were investigated in detail in terms of the composition, crystalline structure, resistivity, thickness and surface roughness. At finally optimized deposition conditions, ultra-thin (∼  10 nm) ­TiNx thin films with a low resistivity of 125 µΩ cm and small surface roughness of 0.297 nm can be obtained. These superior performances together with low-running cost suggest great promise for the ­TiNx thin films to be used as electrodes in microelectronic devices.

1 Introduction With the rapid development of metal–oxide–semiconductor field effect transistor (MOSFET) and dynamic random access memory (DRAM) structures, TiN thin film has been introduced as metal gate and capacitor electrodes owing to its high thermal and chemical stability, low resistivity and low-running cost [1, 2]. Recently, great efforts have been expended in investigating the ferroelectric property of hafnium oxide based thin films, and most of the reports demonstrated that the mechanical confinement offered by TiN top electrode layers during crystallization was critical to induce a distinct ferroelectric phase formation and also to improve the remanent polarization [3–5]. When being used as metal gate and capacitor electrodes, the thermal budget, electrical property and surface morphology of TiN thin films have a significant influence on device performance. The films should be deposited at a temperature lower than the crystallization temperature of doped hafnium oxide (~ 450 °C), which was aimed to keep

* Dayu Zhou [email protected] 1



Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China



Department of Electronic Engineering, Dalian Neusoft University of Information, Dalian 116023, China

2

the doped hafnium oxide in amorphous state before postmetallization annealing [6]. Furthermore, a low resistivity (below 400 µΩ cm) and a low surface roughness were typically preferred [7, 8]. In addition, the film thickness (from a few to a few tens of nanometers) was also restricted to meet the scaling requirement for microelectronic application [8, 9]. TiN thin films can be deposited in various ways [10–15]. One such