Characteristics of ALD tungsten nitride using B2H6, WF6, and NH3 and application to contact barrier layer for DRAM

Soo Hyun Kim, Jun Ki Kim, Ju Hee Lee, Nohjung Kwak, Jinwoong Kim, Sung Hoon Jung, Mi Ran Hong, Sang Hyeob Lee, Josh Collins, Hyunchul Sohn

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Tungsten nitride (W Nx) thin films were grown by atomic layer deposition (ALD) within the temperature range of 200-350°C from diborane (B2 H6), tungsten hexafluoride (W F6), and ammonia (N H3) for application to a contact barrier layer in dynamic random access memory (DRAM). Herein, B2 H6 was used as an additional reducing agent to produce a low-resistivity ALD-W Nx film, and its resistivity was in the range of 300-410 μ cm, depending on the deposition conditions for the ∼10 nm thick film. An increase in the growth rate was observed with increasing deposition temperature, but an almost constant growth rate of ∼0.28 nmcycle was obtained in the temperature range from 275 to 300°C. The properties of the as-deposited film, including the resistivity, WN ratio, density, B and F impurity content, and phase, were affected by the deposition temperature and B2 H6 flow rate during the process. As the deposition temperature and B2 H6 flow rate increased, the WN ratio and film density increased and the impurity content decreased, leading to a reduction in the resistivity of the film. An increased WN ratio was found to be favorable to the formation of a face-centered-cubic Β- W2 N phase. Excellent step coverage was obtained even on a 0.14 μm diameter contact hole with an aspect ratio of 16:1. The ALD-W Nx film in this study was thermally stable to annealing at 800°C for 30 min, but after annealing at 900°C, it converted to body-centered-cubic α-W with the accompanying release of N. The ALD-W Nx film was evaluated as a barrier layer for W-plug deposition for 70 nm design-rule DRAM. The results showed that the integration scheme with ALD-W Nx showed lower contact resistance than metallorganic chemical vapor deposition TiN or Ti Cl4 -based chemical vapor deposited TiN.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume154
Issue number8
DOIs
Publication statusPublished - 2007 Jul 6

Fingerprint

Tungsten
Atomic layer deposition
Nitrides
Data storage equipment
Temperature
Flow rate
Annealing
Impurities
Reducing Agents
Metallorganic chemical vapor deposition
Reducing agents
Contact resistance
Ammonia
Thick films
Aspect ratio
Vapors
Thin films

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

Cite this

Kim, Soo Hyun ; Kim, Jun Ki ; Lee, Ju Hee ; Kwak, Nohjung ; Kim, Jinwoong ; Jung, Sung Hoon ; Hong, Mi Ran ; Lee, Sang Hyeob ; Collins, Josh ; Sohn, Hyunchul. / Characteristics of ALD tungsten nitride using B2H6, WF6, and NH3 and application to contact barrier layer for DRAM. In: Journal of the Electrochemical Society. 2007 ; Vol. 154, No. 8.
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abstract = "Tungsten nitride (W Nx) thin films were grown by atomic layer deposition (ALD) within the temperature range of 200-350°C from diborane (B2 H6), tungsten hexafluoride (W F6), and ammonia (N H3) for application to a contact barrier layer in dynamic random access memory (DRAM). Herein, B2 H6 was used as an additional reducing agent to produce a low-resistivity ALD-W Nx film, and its resistivity was in the range of 300-410 μ cm, depending on the deposition conditions for the ∼10 nm thick film. An increase in the growth rate was observed with increasing deposition temperature, but an almost constant growth rate of ∼0.28 nmcycle was obtained in the temperature range from 275 to 300°C. The properties of the as-deposited film, including the resistivity, WN ratio, density, B and F impurity content, and phase, were affected by the deposition temperature and B2 H6 flow rate during the process. As the deposition temperature and B2 H6 flow rate increased, the WN ratio and film density increased and the impurity content decreased, leading to a reduction in the resistivity of the film. An increased WN ratio was found to be favorable to the formation of a face-centered-cubic Β- W2 N phase. Excellent step coverage was obtained even on a 0.14 μm diameter contact hole with an aspect ratio of 16:1. The ALD-W Nx film in this study was thermally stable to annealing at 800°C for 30 min, but after annealing at 900°C, it converted to body-centered-cubic α-W with the accompanying release of N. The ALD-W Nx film was evaluated as a barrier layer for W-plug deposition for 70 nm design-rule DRAM. The results showed that the integration scheme with ALD-W Nx showed lower contact resistance than metallorganic chemical vapor deposition TiN or Ti Cl4 -based chemical vapor deposited TiN.",
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Characteristics of ALD tungsten nitride using B2H6, WF6, and NH3 and application to contact barrier layer for DRAM. / Kim, Soo Hyun; Kim, Jun Ki; Lee, Ju Hee; Kwak, Nohjung; Kim, Jinwoong; Jung, Sung Hoon; Hong, Mi Ran; Lee, Sang Hyeob; Collins, Josh; Sohn, Hyunchul.

In: Journal of the Electrochemical Society, Vol. 154, No. 8, 06.07.2007.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Characteristics of ALD tungsten nitride using B2H6, WF6, and NH3 and application to contact barrier layer for DRAM

AU - Kim, Soo Hyun

AU - Kim, Jun Ki

AU - Lee, Ju Hee

AU - Kwak, Nohjung

AU - Kim, Jinwoong

AU - Jung, Sung Hoon

AU - Hong, Mi Ran

AU - Lee, Sang Hyeob

AU - Collins, Josh

AU - Sohn, Hyunchul

PY - 2007/7/6

Y1 - 2007/7/6

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AB - Tungsten nitride (W Nx) thin films were grown by atomic layer deposition (ALD) within the temperature range of 200-350°C from diborane (B2 H6), tungsten hexafluoride (W F6), and ammonia (N H3) for application to a contact barrier layer in dynamic random access memory (DRAM). Herein, B2 H6 was used as an additional reducing agent to produce a low-resistivity ALD-W Nx film, and its resistivity was in the range of 300-410 μ cm, depending on the deposition conditions for the ∼10 nm thick film. An increase in the growth rate was observed with increasing deposition temperature, but an almost constant growth rate of ∼0.28 nmcycle was obtained in the temperature range from 275 to 300°C. The properties of the as-deposited film, including the resistivity, WN ratio, density, B and F impurity content, and phase, were affected by the deposition temperature and B2 H6 flow rate during the process. As the deposition temperature and B2 H6 flow rate increased, the WN ratio and film density increased and the impurity content decreased, leading to a reduction in the resistivity of the film. An increased WN ratio was found to be favorable to the formation of a face-centered-cubic Β- W2 N phase. Excellent step coverage was obtained even on a 0.14 μm diameter contact hole with an aspect ratio of 16:1. The ALD-W Nx film in this study was thermally stable to annealing at 800°C for 30 min, but after annealing at 900°C, it converted to body-centered-cubic α-W with the accompanying release of N. The ALD-W Nx film was evaluated as a barrier layer for W-plug deposition for 70 nm design-rule DRAM. The results showed that the integration scheme with ALD-W Nx showed lower contact resistance than metallorganic chemical vapor deposition TiN or Ti Cl4 -based chemical vapor deposited TiN.

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