Texture and microtexture of copper films prepared by the self-ion assisted deposition technique on barrier layers with d
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Texture and microtexture of copper films prepared by the self-ion assisted deposition technique on barrier layers with different structure Oleg V. Kononenko1, Victor N. Matveev1, Andrei G. Vasiliev2, Ivan Khorin2, Tejodher Muppidi, David P. Field School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920 USA. 1 Institute of Microelectronics Technology and High Purity Materials, RAS, 143432 Chernogolovka, Moscow Region, Russia. 2 Moscow State Institute of Radioengineering, Electronics and Automation (Technical University), Department of Condensed Matter Electronics, 117454 Moscow, Russia.
ABSTRACT Cu may diffuse into the active areas of semiconductors resulting in degradation of the devices. Therefore Cu is isolated from silicon wafers by barrier layers. In this study, copper films were deposited onto silicon substrates coated using polycrystalline Ta3N5 and amorphous α-C:H barrier by the partially ionized beam deposition technique at 6 kV bias, to investigate an influence of barrier layer structure on texture and microstructure of Cu films. After deposition, films were annealed under vacuum. Texture of the films was studied by X-ray diffraction and further microstructural analysis of the copper films was performed by orientation imaging microscopy. Results of the structural analysis reveal large (100) grains in films deposited on αC:H barrier layer and a bi-modal texture in films on Ta3N5.
INTRODUCTION The change from Al to Cu interconnects in IC manufacture brings multiple advantages [1]; namely performance, reliability and cost. The lower resistivity of copper (1.67 µΩ⋅cm vs 2.65 µΩ⋅cm for aluminum) allows finer interconnects with lower resistive losses, resulting in shorter on-chip resistance–capacitance (RC) time delays. The higher mass and melting point of Cu make it less susceptible to electromigration than aluminum, and less likely to fail under stress. Many techniques have been used to deposit thin Cu films including physical vapor deposition (PVD), chemical vapor deposition (CVD), and electrochemical deposition (ECD). The partially ionized beam (PIB) deposition technique has a certain attraction for Cu in that the particle energy is controlled instead of the substrate temperature, and results in rapid nucleation of the metal on the substrate. Ultimately, films with relatively smooth surfaces grown at low temperatures are obtained. The microstructure of Cu films deposited by the PIB technique was discussed by Koh, et al [2]. They deposited 320 nm thick Cu films using the PIB technique. The films were annealed at 500 ºC for 30 minutes subsequent to deposition. No grain size information was reported in this work, and the crystallographic textures were estimated using θ-2θ scans. The resulting microstructures of all films consisted of (111) fiber textures. The texture strength increased with accelerating potential during deposition for both the as-deposited and annealed films. J3.5.1 Downloaded from https://www.cambridge.org/core. YBP Library Services, on 20 Aug 2018 a
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