Reduction of selectivity loss probability on dielectric surface during chemical vapor deposition of tungsten using fluorinated oxide and removing silanol units on dielectric surface

Kow-Ming Chang*, Shih Wei Wang, Chii Horng Li, Jung Yu Tsai, Ta Hsun Yeh

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Dielectric materials and surface pretreatment are important for the control of selectivity loss during the chemical vapor deposition (CVD) of W in SiH4/H2/WF6 ambient. Water-related silanol (SiOH) units on an oxide surface, which come from a wet cleaning step and moisture in clean room air, are found to act as nucleation centers, resulting in selectivity loss. Removing these silanol units by in situ NF3 plasma pretreatment effectively inhibits the nucleation of W. Reduction of the dielectric constant, as well as doping of fluorine in oxide, was shown to suppress the selectivity loss. This is due to the high electronegativity of the FxSiOy film surface, which repels the WF6 molecules. The resistance to selectivity loss of W on FxSiOy is better than that on BPSG. From these results, nucleation of W is inferred to initiate from the adsorption of WF6 on the insulator surface in the WF6/SiH4/H2 ambient. On the other hand, a novel method that uses FxSiOy as an intermetal dielectric (IMD) or that involves capping on a dielectric material (e.g., BPSG), was proposed to reduce the selectivity loss probability during selective growth processes.

Original languageEnglish
Pages (from-to)6555-6561
Number of pages7
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume35
Issue number12 B
DOIs
StatePublished - 1 Dec 1996
EventProceedings of the 1996 9th International MicroProcess Conference, MPC'96 - Kyushu, Jpn
Duration: 8 Jul 199611 Jul 1996

Keywords

  • BPSG
  • CVD of W
  • Electronegativity
  • FSiO
  • In situ NF plasma pretreatment
  • Selectivity loss
  • Silanol (SiOH)

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