Characteristics of PECVD grown tungsten nitride films as diffusion barrier layers for ULSI DRAM applications |
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Authors: | Byung Lyul Park Dae-Hong Ko Young Sun Kim Jung Min Ha Young Wook Park Sang In Lee Hyeon-Deok Lee Myoung Bum Lee U In Chung Young Bum Koh Moon Yong Lee |
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Institution: | (1) Semiconductor R&D Center, Samsung Electronics Co., LTD, San # 24, Nongseo-Lee, Kiheung-Eup, Yongin-City, 449-900 Kyungki-Do, Korea;(2) Department of Ceramic Engineering, Yonsei University, Seoul |
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Abstract: | We have developed tungsten nitride (W-Nitride) films grown by plasma enhanced chemical vapor deposition (PECVD) for barrier
material applications in ultra large scale integration DRAM devices. As-deposited W-Nitride films show an amorphous structure,
which transforms into crystalline, β-W2N and α-W phases upon annealing at 800°C. The resistivity of the as-deposited films grown at the NH3/WF6 gas flow ratio of 1 is about 160 μω-cm, which decreases to 50 μω-cm after an rapid thermal annealing treatment at 800°C.
In the contact holes with the size of 0.35 μm and aspect ratio of 3.5, the bottom step coverage of the tungsten nitride films
is about 60%, which is about three times higher than that of collimated-TiN films. We obtained contact resistance and leakage
current with the tungsten nitride barrier layer comparable to those with conventional collimated TiN films. The contact resistance
and leakage current are stable upon thermal stressing at 450°C up to 48 h. |
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Keywords: | Diffusion barrier plasma enhanced chemical vapor desposition (PECVD) tungsten nitride ultra large scale integration (ULSI) DRAM |
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