Low-resistivity α-phase tungsten films grown by hot-wire assisted atomic layer deposition in high-aspect-ratio structures

THIN SOLID FILMS

卷:646

Article

Yang, Mengdi¹  Aarnink, Antonius A. I.¹  Schmitz, Jurriaan¹  Kovalgin, Alexey Y.¹ 

[1] Univ Twente, MESA Inst Nanotechnol, POB 217, NL-7500 AE Enschede, Netherlands

关键词: Hot wire;    Tungsten;    ALD;    Alpha-phase;    Low resistivity;    High-aspect-ratio substrates;   

DOI  :  10.1016/j.tsf.2017.12.011

来源: Elsevier

【 摘 要 】

In this work, the so-called hot-wire (HW) assisted atomic layer deposition (HWALD) technique is employed to grow high-purity a-phase tungsten (W) films at a substrate temperature of 275 degrees C. The films are deposited on thermally grown silicon dioxide (SiO2) in a home-built hot-wall reactor, using alternating pulses of WF6 and HW-generated atomic hydrogen in the self-limiting surface-reaction manner characteristic for ALD. A W seed layer, needed to enable the HWALD-W process on a SiO2 surface, is formed prior to each deposition. In-situ spectroscopic ellipsometry is used to monitor the growth behavior and film properties. The films exhibit a high-purity (99 at.%) W, according to X-ray photoelectron spectroscopy. The X-ray diffraction scans reveal the existence of a-phase W. The resistivity measurements by means of four point probe, transfer length method test structures and the Drude-Lorentz SE model all reveal a low resistivity of 15 mu Omega.cm. The high-resolution transmission electron microscopy analysis shows a uniform and conformal coverage of high aspect ratio structures, confirming the effective ALD process and the sufficient diffusion of both WF6 and at-H into deep trenches.

【 授权许可】

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